ABSTRACT Multimodal nanoparticles, utilizing quantum dots (QDs), mesoporous silica nanoparticles (MSNs), and gold nanoparticles (Au NPs), offer substantial potential as a smart and targeted

drug delivery system for simultaneous cancer therapy and imaging. This method entails coating magnetic GZCIS/ZnS QDs with mesoporous silica, loading epirubicin into the pores, capping with

Au NPs, PEGylation, and conjugating with epithelial cell adhesion molecule (EpCAM) aptamers to actively target colorectal cancer (CRC) cells. This study showcases the hybrid

QD@MSN-EPI-Au-PEG-Apt nanocarriers (size ~65 nm) with comprehensive characterizations post-synthesis. In vitro studies demonstrate the selective cytotoxicity of these targeted nanocarriers

SIMILAR CONTENT BEING VIEWED BY OTHERS SEMICONDUCTING POLYMER NANOPARTICLES FOR PHOTOTHERMAL ABLATION OF COLORECTAL CANCER ORGANOIDS Article Open access 15 January 2021 IN SITU

VALENCE-TRANSITED ARSENIC NANOSHEETS FOR MULTI-MODAL THERAPY OF COLORECTAL CANCER Article Open access 01 March 2025 NANOMEDICINE IN CANCER THERAPY Article Open access 07 August 2023

INTRODUCTION Colorectal cancer (CRC) has turned into a big concern for human health as the third most common malignancy in both sexes worldwide1. Conventional treatment modalities often fail

against CRC resistance and recurrence, leading to metastasis and lower survival rates2,3. Therefore, early diagnosis and more efficient treatments are crucially required. Multimodal

theranostic nanoparticles that emerged from nanotechnology can be designed to carry drugs, imaging contrast, and radiosensitizing agents to enhance therapeutic outcomes while ensuring

patient convenience. Regarding the common aggressive approach to remove tumors by surgery, improved imaging modalities via contrast agents, can guide the surgeons to remove cancerous tissue

completely4,5. Furthermore, using targeted nanocarriers could simultaneously optimize the delivery of chemo-drugs as well as radiosensitizing agents. In this way radiotherapy would be

initiated only when the radiosensitizers deduced from imaging modalities are high in the tumor and at low levels in the surrounding healthy tissues. Although each imaging modality such as

fluorescence imaging (FLI), magnetic resonance imaging (MRI), and X-ray computed tomography (CT) has its own limitations, combining different methods would accomplish a good vision of the

tumor tissue6. To this aim, designing traceable nanoparticles in the body by different imaging modalities that contain a combination of both chemotherapeutic and radiosensitizing agents

could lead to better cancer diagnosis and eradication of therapeutic resistance. Fluorescence (FL), the phenomenon of charged carriers recombination in excited fluorophores, grants the best

sensitivity in optical imaging; specifically during the elimination of tumors, FL guides the scalpel. To use this advantage, semiconductor nanocrystals known as quantum dots (QDs) are more

attractive compared to fluorescent dyes7. The unique optical properties such as broad absorption and narrow emission spectra with highly bright and size-dependent emission in addition to

high resistance to photobleaching, have attracted much attention towards QDs as candidates for bio-imaging applications8. Ternary I-III-VI semiconductor quantum dots such as CuInS2 and

AgInSe2 are more bio-applicant than conventional II–VI cadmium-based QDs such as CdSe and CdTe or PbS9. In the case of in vivo FL imaging, a derivative formulation of CuInS2 QDs, Zn–Cu–In–S

(ZCIS) and ZCIS/ZnS quaternary QDs, showed excellent emission in the FL region as well as low toxicity and high lifetime10. To overcome FL low tissue penetration depth, MRI could compensate

with high-quality 3-dimensional images. For this purpose, paramagnetic ions (Mn2+ and Gd3+) as _T__1_ MR contrast agents could be incorporated into QDs attending fluorescence properties in

order to develop dual-modal imaging probes11. Despite many advantages of QDs, solubility in aqueous media is an obstacle to their use12, for which there are several solutions including

ligand exchange, amphiphilic combination, and silica coating (surface silanization)7. Mesoporous silica is an emerging inorganic compound in nanobiotechnology specially used in coating as

core-shell structures because of its interesting features such as biocompatibility, facile surface modification, optical transparency, external porosity, chemical stability, and low

cost13,14. Thus, mesoporous silica nanoparticles (MSNs) which are incorporated with QDs carry both benefits and resolve the problems associated with QDs bio-applications12. Additionally,

MSNs are well known for their high loading capacity as an efficient drug delivery system (DDS)15. In addition to the capacity for loading the chemo drugs in pores of MSNs, drug release could

be controlled by bulky nanoparticles at pore entrances in response to external stimuli16,17. The acidic pH of tumor microenvironment (TME) and inner space of cellular endosomes are good

triggers for drug release, which could be controlled by several gatekeepers such as gold nanoparticles (Au NPs)18. Besides the gatekeeping role of Au NPs and their traceability by CT scan,

their radiosensitization effects for cancer radiotherapy are widely studied19,20. Radiotherapy (RT) alone using X-ray, could produce highly toxic hydroxyl (•OH) and other free radicals which

induce double-stranded DNA breaks and inhibit cell proliferation21. Although RT is one of the most effective approaches for tumor control, exposure to ionizing radiation (IR) via an

external beam (EB) or from an internally placed source (brachytherapy) could also damage the surrounding normal tissues22. Thus, inevitable limitations for radiation doses must be exerted at

a tolerable level to lower the side effects on normal tissues. Recently, nanoparticles with high atomic number (Z) elements (Au, Gd, Bi) appeared as fundamental agents to enhance the

efficacy of RT by increasing the X-ray absorption coefficient23,24. Notably, Au NPs as nanoscale radiosensitizers have been extensively studied due to their ease of synthesis and

controllable physicochemical properties22. Meanwhile, size and shape control of Au NPs can be achieved by versatile synthesis methods25,26,27, and particle stability in the biological

environment can also be obtained by a protective coating28. Heterobifunctional polyethylene glycols (PEGs) with thiol terminal, as a type of FDA-approved polymer29, are able to bind

conveniently to the surface of Au NPs16. Therefore, nanocarriers pharmacological properties such as half-life, toxicity, hemolysis of erythrocytes, and recognition by host immune cells,

could be improved by PEGylation of Au NPs which close the MSN pores30,31. Cancer chemotherapy suffers from several challenges induced by severe side effects for patients due to the 

accumulation of anti-proliferative drugs in normal tissues. However, nanocarriers are able to partially compensate restrictions of conventional inefficient chemotherapy methods and increase

available drugs at the tumor site by enhanced permeability and retention (EPR) effect32. To maximize drug delivery efficiency and especially increase the endocytosis to cancer cells in the

TME, in addition to minimizing systemic side effects, targeted therapy aroused new generations of DDSs33. In this regard, designing cost-effective ligands such as aptamers with high affinity

to bind to the particular overexpressed cancer cell receptors, comprises several benefits because of their high stability, low toxicity, and low immunogenicity34. Epithelial cell adhesion

molecule (EpCAM or CD326) is an overexpressed surface receptor known as a tumor-associated antigen for CRC cells especially tumor-initiating cells (primitive stem cell-like). Moreover, EpCAM

acts as a prometastatic molecule due to its role in the negative modulation of cadherin-mediated cell adhesion, leading to the defection of cell-to-cell contacts35,36,37. Since the healthy

normal tissues express EpCAM at a lower level38,39, DDSs armed with EpCAM cognitive aptamers such as SYL3C could be used in active targeting delivery to CRC cells for more efficient

theranostic applications40. In the current study, we designed, synthesized, and investigated multimodal theranostic nanoparticles for CRC drug delivery, utilizing QDs coated with mesoporous

silica to hybridize their excellent properties in imaging and therapy. Epirubicin (EPI) was loaded in QD@MSNs, and capped with Au NPs for controlled release at acidic pH. The nanocarriers

were then PEGylated and conjugated with EpCAM DNA aptamer for active targeting. After evaluating the physicochemical properties of nanocarriers, in vitro experiments for cellular uptake,

cell toxicity, colony formation ability, and apoptosis measurements were performed. In the final step, the anti-tumor efficiency and biosafety of prepared formulations in combination with

radiotherapy were evaluated in immunocompromised C57BL/6 mice bearing human HT-29 tumors. Meanwhile, FLI, MRI, and CT scan were conducted to visualize the biodistribution of QDs and Au NPs

with different imaging modalities (Fig. 1). RESULTS CHARACTERIZATION RESULTS INDICATED SUCCESSFUL SYNTHESIS OF NPS Initially, QD and QD@MSN as the main backbones were synthesized as

described in the experimental section. As shown in Fig. 2a, b, d, the prepared QD and QD@MSN were dispersed in chloroform and water, respectively, and could emit a bright orange and red

luminescence under the ultraviolet lamp as well as FL microscope compared to visible light. Furthermore, UV/Vis absorption and photoluminescence (PL) emission spectra revealed the optical

characteristics (Fig. 2e, f). The as-prepared QDs showed a fluorescence emission peak at ~610 nm by an excitation filter at 450 nm (Fig. 2e), confirming the equivalent ratio of Zn/Cu as

reported previously10. Notably, the PL emission spectra after coating QDs with mesoporous silica illustrated a redshift (~20 nm) as expected and significantly enhanced when combined with

EPI. Moreover, the absorbance of QD@MSN increased within the whole absorption range compared to QDs (Fig. 2f), which might be due to the coating of the silica shell leading to increased

particle size and more light scattering41,42. The total radiant efficiency of FL formulations including QD, QD@MSN, EPI, and QD@MSN-EPI was evaluated quantitatively via FL imaging and

confirmed the combined FL properties of QD and EPI in QD@MSN-EPI (Fig. 2c, g). As shown in Fig. 2h, the UV/Vis spectrum of as-prepared Au NPs revealed a maximum peak of 517 nm due to surface

plasmon resonance (SPR) absorption43. The susceptibility of prepared QDs and mesoporous silica-coated QDs was examined in the presence of a magnetic field and by the vibrating-sample

magnetometer (VSM) technique (Fig. 2i, l). The hysteresis curve of VSM results and the paramagnetic properties of QD and QD@MSN were clearly confirmed with their increased magnetization (Ms)

by high magnetic field44,45. In order to confirm that Gd and Au content was sufficient to produce contrast in an MR and CT image, the same serial concentrations of nanoparticles were

assessed (Fig. 2j, k). Furthermore, to investigate the effectiveness of nanoparticles by a concentration-independent measurement, _R__1_ relaxivity, as well as X-ray attenuation, were

analyzed by the slope of the plot of inverse relaxation time (1/_T__1_ (s−1)) and attenuation intensity (Hounsfield unit) versus nanoparticles concentration (Fig. 2m, n). According to these

results, hybridized nanoparticles containing Gd and Au could be detected by MR and X-ray CT techniques. According to Supplementary Table 1 and Fig. 3, the particle size of synthesized NPs

was measured by dynamic light scattering (DLS) and high-resolution-transmission electron microscopy (HR-TEM). Results indicated that QD, QD@MSN, and Au NP had an average size of around 4,

40, and 6 nm, respectively (Fig. 3a–d and Supplementary Fig. 1a, b). Moreover, Fig. 3b shows the corresponding selected area electron diffraction (SAED) pattern of the GZCIS/ZnS QDs

illuminating that the prepared GZCIS/ZnS QD crystals are amorphous, which might be due to the surface of the QDs comprising organic moiety. Atomic force microscopy (AFM) and field

emission-scanning electron microscopy (FE-SEM) results demonstrated a uniform spherical morphology and monodispersity of mesoporous silica-coated QDs and PEGylated QD@MSN (Fig. 3e–h). While

the growth of silica on QDs was confirmed by increased particle size and surface roughness of QD@MSN based on FE-SEM and AFM results (Fig. 3e, Supplementary Fig. 1c, e), the roughness of the

surface relatively decreased after incorporation of PEG (Fig. 3f and Supplementary Fig. 1d, f). In order to analyze the crystal structure and composition of the as-prepared QD and QD@MSN,

X-ray diffraction (XRD) patterns were determined in the range of 10–80° at 2θ. As illustrated in Fig. 3i, the XRD pattern of the GZCIS/ZnS QDs showed five major peaks at 2θ of 19.15°, 26.7°,

30.01°, 42.9°, and 46.2° corresponding to the crystal planes [1 0 0], [0 0 2], [0 1 1], [1 1 1] and [1 1 0], respectively. Moreover, QD@MSN represented a broad peak at 2θ = 22.6, which was

attributed to the amorphous silica. Drug loading and pore-capping of prepared backbone nanoparticles (QD@MSN) were confirmed by particle size and zeta potential alterations (Supplementary

Table 1) in addition to N2 physisorption analysis. The N2 absorption/desorption isotherms of QD@MSN displayed type IV isotherm (H1-type hysteresis loops) with capillary condensation step (at

P/P0 = 0.99) representing mesoporous structure (Fig. 3j). Moreover, the Brunauer-Emmett-Teller (BET) surface areas, total pore volume and Barrett-Joyner-Halenda (BJH) pore diameter of

QD@MSN were calculated as 493.42 m2/g, 3.75 cm3/g, and 1.64 nm, respectively (Fig. 3j, k). Whereas surface area and total pore volume for QD@MSN-EPI-Au decreased to 220.83 m2/g and 0.68

cm3/g, respectively. Therefore, the obtained results illuminated the surface structure as well as the successful drug loading and pore-capping of QD@MSN by Au NPs. Thermogravimetric analysis

(TGA) was performed to consider thermal stability and the amount of conjugated organic groups. The most weight loss (~38%) was associated with QD@MSN-EPI-Au-PEG which contains more organic

components compared to bare QD (~11%) and QD@MSN backbone (~22%), whereas TGA results of bare QD depicted the least weight loss due to high amount of inorganic content (Fig. 3l). Although

nanoparticles armed with EpCAM aptamer (Apt) were evaluated by particle size and zeta potential, agarose gel electrophoresis was also conducted to indicate efficient conjugation of Apt on

the surface of QD@MSN-EPI-Au-PEG. As shown in Fig. 3m, the sharp band of free EpCAM aptamer in front of the 50 base pair DNA size marker, illustrated the expected molecular weight of the

aptamer. Meanwhile, aptamer conjugation was confirmed by the sharp band of QD@MSN-EPI-Au-PEG-Apt remained in the well compared to QD@MSN-EPI-Au-PEG. The functional groups of different

synthesized NPs were confirmed by Fourier transform infrared (FT-IR) spectra (Supplementary Fig. 2, 3). The characteristic peaks of metal oleate complexes (Zn(OA)2, Cu(OA)2, In(OA)3 and

Gd(OA)3) at 1425–1457 and 1546–1589 cm−1 were ascribed to the stretching vibrations of COO− bands of oleate chains while the peaks at 2852 and 2923 cm−1 were attributed to C–H stretching

vibration which were also observed in the FT-IR spectrum of QDs41. After coating QDs with amine-functionalized mesoporous silica, stretching vibrations of Si–O and Si–O–Si bonds as well as

Si–O and NH2 bending vibrations were seen at 800, 1070, 460, and 1583 cm−1, respectively in addition to the absorption peaks of C–H bond46,47,48. The FT-IR spectra of EPI-loaded QD@MSN

illustrated the stretching vibration of the CH2 group at 2920 and 2850 cm−1 in addition to its bending vibration absorption peak at 1385 cm−149. Moreover, additional hydroxyl (O–H) and

carbonyl (C = O) groups absorption peaks as well as the presence of NH2 bending vibration appeared at 3440, 1617, and 1581 cm−1 of QD@MSN-EPI, respectively50. The successful synthesis of Au

NPs was illuminated by FT-IR measurements demonstrating surface functionalization. The citrate characteristic peaks were observed at 1386 and 1598 cm−1 corresponding to the symmetric and

anti-symmetric stretching of COO−51. Furthermore, the sharp peaks at 1062 and 3411 cm−1 were attributed to  the stretching vibration of O–H and C–O indicating the presence of alcohol groups,

whereas weak bands at 2915, and 2852 were assigned to stretching vibration of C–H corresponding to alkane groups on the gold NPs surface52. When the gold nanoparticles capped the QD@MSN-EPI

pores, the functional groups attributed to carboxylate (COO−) and hydroxyl (O–H) groups of citrate at 1617, 1581, 2920, and 3440 were detected18. After aggregation of PEG on the nanocarrier

surface, the presence of stretching vibrations at 1360, 1420, 1612, 1712, 2920, and 3400 ascribed respectively to C–O, COO−, C = O, C–H, and O–H were observed due to free end of

heterofunctional PEG (–COOH)53. At the last step of synthesis, the weak bending and stretching vibrations of N–H could indicate the EpCAM aptamer conjugation by EDC/NHS amide coupling

reaction between carboxyl-modified PEG and amino-modified aptamer54,55. The elemental composition and chemical purity of as-synthesized nanoparticles in each step are depicted in

energy-dispersive X-ray (EDX) spectra (Supplementary Fig. 4a) and weight percentage (W%) of the main elements (Gd, In, Cu, Zn, Si, Au, C, O, N, and P) are summarized in Supplementary Table 

2. EDX mapping analysis of QD@MSN-NH2 as the prepared backbone was also carried out and illuminated the distribution and existence of the main elements in the structure confirming the

successful fabrication (Supplementary Fig. 4b). The particle size and polydispersity index (PDI) of the final formulation, QD@MSN-EPI-Au-PEG-Apt, demonstrated excellent colloidal stability

in two different media, namely PBS and PBS containing 30% v/v fetal bovine serum (FBS), as depicted in Supplementary Table 3. The results obtained through the DLS method, at three different

time points, confirmed that the final nanoparticles remained remarkably stable in PBS for up to 48 h, with minimal increase in size. However, when the nanoparticles were exposed to the media

of PBS containing 30% FBS under the same conditions, an increase in nanoparticle size was observed, potentially attributed to protein adsorption induced by FBS56. These findings may support

the influence of PEGylation and the relatively high zeta potential (~−22 mV) of QD@MSN-EPI-Au-PEG-Apt on long-term stability during incubation in a physiological bio-environment30,57. DRUG

LOADING AND INTELLIGENT RELEASE WERE CONFIRMED As described in the experimental section, drug loading assessments including encapsulation efficiency (EE%) and drug loading capacity (LC%)

were measured as 70% ± 1.56 and 25% ± 1.43, respectively. The in vitro drug release was performed in acidic and neutral solutions (pH = 5.4, 6.4, and 7.4) simulating endosomes, TME, and

physiological body fluids, respectively. As shown in Fig. 3n, EPI release from QD@MSN-EPI-Au was faster in acidic pHs (5.4 and 6.4) compared to physiological pH. The burst release of EPI

occurred within the first 6 h, followed by the slow release in the next 24 h. Moreover, the most cumulative drug release after 6 days was associated with acidic pHs (76.33% and 52.15%)

compared to less release at physiological pH (17.07%). According to the results, Au NPs could well play their gatekeeping role in controlled drug delivery. PEGYLATION LED TO LESS HEMOLYSIS

In order to evaluate the hemolysis activity of prepared bare nanoparticles in comparison to PEGylated nanocarriers, a hemolysis assay was performed. The influence of PEG layer as a

biodegradable polymer on lysis behavior was investigated31. The quantification of hemolysis in the presence of QD@MSN as the backbone and QD@MSN-EPI-Au-PEG with different concentrations

(12.5 to 400 μg/ml in PBS) showed significant differences (Fig. 4). The PEGylated nanocarriers showed less than 2, 3 and 5% (low rate) hemolysis at 4, 12 and 24 h, respectively. TARGETED NPS

HAD HIGHER UPTAKE IN CRC CELLS The uptake of prepared formulations was evaluated on both EpCAMpositive human colon cancer (HT-29) and EpCAM-negative Chinese hamster ovary (CHO) cell lines.

The quantitative results by flow cytometry showed higher internalization of QD@MSN-EPI-Au-PEG-Apt than QD@MSN-EPI-Au-PEG in HT-29 cells, representing the specific entrance due to interaction

of EpCAM receptor and its aptamer (Fig. 5a). Besides, this comparison indicated no difference in CHO cells with low expression of EpCAM receptor (Fig. 5b). However, the entrance of Free EPI

in both cell lines was high due to nonspecific passive uptake through the lipid bilayer. Moreover, QD@MSNs which were taken up nonspecifically via clathrin-coated vesicles led to partial

detection of QD red emission by FL2 channel (Fig. 5a, b). As shown in Fig. 5c, d and Supplementary Fig. 5, the cellular uptake and consequently red fluorescence of QD and EPI were

qualitatively confirmed by fluorescent microscopy. The strong red fluorescence of Free EPI and QD@MSN at nucleus and cytoplasm, respectively, was more obvious in HT-29 cells treated with

QD@MSN-EPI-Au-PEG-Apt compared to QD@MSN-EPI-Au-PEG (Fig. 5c). Moreover, no significant differences were observed in CHO cells treated with QD@MSN-EPI-Au-PEG-Apt and QD@MSN-EPI-Au-PEG

indicating the EpCAM receptor-mediated endocytosis in HT-29 cells (Fig. 5d). As shown in Supplementary Fig. 5, accumulation of EPI free-nanoparticles (QD@MSNs) was more in the cytoplasm

compared to EPI loaded-nanocarriers, which emitted bright red FL from both nucleus and cytoplasm of HT-29 cells. The obtained results represented not only the targeted uptake of nanocarriers

but also the FL enhancement of QDs by EPI. TARGETED NPS IN COMBINATION WITH RT RESULTED IN HIGHER CELL DEATH The synergistic cytotoxic effects of targeted drug delivery and radiotherapy

were further evaluated by flow cytometry to analyze the possible enhancement of apoptosis in HT-29 cells. 24 h post-treatment of EpCAM+ HT-29 cells with Free EPI, QD@MSN-EPI-Au-PEG,

QD@MSN-EPI-Au-PEG-Apt, QD@MSN-EPI-Au-PEG-Apt + RT and untreated cells with and without RT as controls, fluorescein isothiocyanate (FITC)-annexin V/propidium iodide (PI) staining was

performed. Although about 99% of untreated cells were viable, the percentage of early and late apoptotic cells (Q3 + Q2) increased to 6.6%, 26.5%, 81.3%, and 84.4% in RT, QD@MSN-EPI-Au-PEG,

Free EPI, and QD@MSN-EPI-Au-PEG-Apt treated HT-29 cells, respectively (Fig. 5e). More importantly, cells receiving the combination of targeted nanoparticles and radiotherapy eventuated to

the least viable and the most apoptotic cell populations, confirming the synergistic cytotoxic effects. CYTOTOXICITY ENHANCEMENT OF TARGETED NPS WAS CONFIRMED BY MTT ASSAY To investigate the

cytotoxicity of different treatment groups including free drug, targeted, and nontargeted NPs, 3‑(4,5‑dimethylthiazol‑2‑yl)‑2,5‑diphenyltetrazolium bromide (MTT) assay was performed on

HT-29 and CHO cells. The results illustrated the significant higher toxicity of EpCAM aptamer-conjugated nanocarries on EpCAM-expressing cells (HT-29) in comparison with nanocarriers without

aptamer at 24, 48, and 72 h (Fig. 6a). Besides, targeted nanocarriers showed the lowest toxicity on CHO cells as EpCAM-negetive cells compared to nontargeted and Free EPI (Fig. 6b).

Furthermore, no significant toxicity related to QD@MSN as backbone was observed on HT-29 and CHO cells (Supplementary Fig. 6a, b). The IC50 values of the three groups at three-time points

are summarized in Supplementary Table 4. COMBINATION OF TARGETED NPS AND RT LED TO MORE CYTOTOXICITY Since the capability of Au NPs to sensitize radiotherapy has been confirmed20, the

combination approach based on this ability was investigated with targeted drug carriers containing Au NPs using the clonogenic assay. For this purpose, after treatment with five

concentrations of final NPs (6.25 to 100 µg/ml) and two RT doses (3 Gy and 6 Gy), the ability of HT-29 and CHO cells for colony formation was evaluated. HT-29 cells pre-treated with

QD@MSN-EPI-Au-PEG-Apt and irradiated with 3 and 6 Gy radiation revealed a remarkable reduction in survival fraction (SF), as compared with the cells subjected to irradiation in a paired

statistical comparison. Notably, the colony formation of HT-29 cells after treatment with 3 and 6 Gy irradiation in combination with the highest concentration of targeted nanoparticle (100 

µg/ml) were 2.2% and 0.9%, respectively, whereas single treatment with 3 and 6 Gy irradiation led to about 73% and 43% colony formation (Fig. 6c, d, f, g). On the other hand, the reduction

of SF due to NPs was not much different with RT alone in CHO cells, representing the lack of EpCAM-mediated uptake (Fig. 6c, e, f, h). Based on these results, the combination of

radiosensitizing and chemotherapeutic effects of QD@MSN-EPI-Au-PEG-Apt showed the highest toxicity on HT-29 cells, however irradiation by 3 Gy revealed more difference between HT-29 and CHO

cells. GREAT AND SELECTIVE ANTI-TUMOR EFFECTS OF TARGETED NPS IN COMBINATION WITH RADIOTHERAPY Following the immunosuppression procedure and tumorigenesis (Fig. 7a), female immunocompromised

C57BL/6 mice bearing HT-29 tumors exhibited angiogenesis at the tumor region (red arrow) and were subsequently prepared for combinational treatment involving radiotherapy (Fig. 7b).

Intravenous administration of different formulations was introduced, and the efficacy of nanocarriers in inhibiting tumor growth was evaluated by measuring tumor volumes during the treatment

period (Fig. 7c). The anti-tumor effects of every treatment group are shown in Fig. 7d, e, representing significant reduction of final tumor size compared to the control group. More

importantly, the final formulation as QD@MSN-EPI-Au-PEG-Apt had the best anti-tumor efficiency, especially in combination with RT, which almost led to tumor elimination. Non-targeted

formulations such as Free EPI and QD@MSN-EPI-Au-PEG exhibited lower tumor inhibition compared to targeted nanocarriers. Furthermore, the highest level of tumor cell death appeared in both

targeted nanocarriers treatment groups, with or without irradiation, as shown by hematoxylin and eosin (H&E) and terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end

labeling (TUNEL) staining of the tumor tissues (Fig. 7f). Through H&E staining, the mice treated with QD@MSN-EPI-Au-PEG-Apt+RT illuminated the most nuclear fragmentation and nucleolysis

of tumor cells compared to other groups. Due to green fluorescence intensity after TUNEL staining (DNA damage area) in tumor tissues of mice treated with targeted nanocarriers, especially

in combination with RT, it was estimated that the main cell death mechanism is apoptosis. According to these results, the anti-tumor properties of prepared nanocarriers confirmed the

targeted delivery of EPI as well as the effectiveness of combined radiation therapy in vivo. BIOSAFETY OF PREPARED NPS WAS CONFIRMED IN VIVO The biosafety of prepared formulations was

evaluated by three variables after 15 days of treatment in vivo. The measurement of mice body weights illustrated a significant (_p_ < 0.001 and _p_ < 0.0001) decrease in Free

EPI-treated animals compared to targeted and PBS-treated groups (Fig. 8a). As shown in Fig. 8b, the liver weight bar chart of different groups revealed slight changes except for

administration of Free EPI, which represented a remarkable reduction. H&E staining of major organs was performed to assess possible side effects of various treatment groups (Fig. 8c).

Histopathological studies of heart tissue showed multifocal necrosis associated with calcification in Free EPI treatment group, whereas cardiomyocytes of the other groups were clear and

arranged in good order without congestion, hemorrhage, inflammation, or necrosis. Light microscopic examination of lung tissue showed no inflammation, edema, or necrosis in treatment groups

except for Free EPI-treated mice, which represented severe side effects, including peribronchiolar (black arrow) and perivascular mononuclear cell inflammation (red arrow) associated with

infiltration of mononuclear cells into the lung parenchyma. The analysis of H&E-stained spleen tissues of the Free EPI treatment group revealed severe degeneration and necrosis of white

pulp and red pulp (black arrow) in addition to hemosiderin pigment deposition associated with scattered red pulp hemosidrophages (red arrow), while other groups showed normal histological

structure of the white and red pulps and sinusoids. Light microscopic observation of kidney tissue from the Free EPI-treated group showed degenerative and necrotic changes in the renal

tubular epithelium (blue arrows), interstitial nephritis including variable infiltration by mononuclear inflammatory cells (red arrow), renal hemorrhage (yellow arrow), and congestion (black

arrows) with red blood cells. Kidney analysis of other groups revealed normal renal tissue appearance with normal Bowman’s capsule and renal tubules. As the last organ, the liver histology

of different treatment groups except the Free EPI was also normal, lobules with central vein were clearly delineated and no hepatocellular degeneration, necrosis, or inflammatory cells were

found. However, the liver observation of the Free EPI group demonstrated severe and diffuse degeneration and necrosis of hepatocytes (black arrows), focal accumulation of inflammatory cells

in the liver tissue as well as portal area (red arrows). NPS WERE EFFICIENTLY TRACKED BY EX VIVO FLUORESCENCE IMAGING Fluorescence intensity of EPI and QDs was measured by the KODAK IS in

vivo imaging system in the liver, kidney, spleen, heart, lung and tumor tissue (Fig. 9e, f). The initial results indicated the fluorescence property of QD@MSN alone and its enhancement in

combination with EPI (Fig. 9a, b). Although the distribution of Free EPI, QD@MSN, QD@MSN-EPI-Au-PEG, and QD@MSN-EPI-Au-PEG-Apt in different animal organs was observed at 12 and 24 h

post-injection, the mean intensity of non-targeted formulations in the main organs was way higher than targeted nanocarriers (Fig. 9c, d). More importantly, the QD@MSN-EPI-Au-PEG-Apt

experimental group showed the most tumor accumulation at both time points as well as the minimum distribution in main organs after 24 h compared to Free EPI and non-targeted nanoparticles

(Fig. 9a–d). Additionally, the merged fluorescence microscopy images of tumor sections, combining emissions from DAPI, EPI, and QDs, clearly showed a significant uptake of targeted

nanoparticles in the tumor cells of the mice in different treatment groups (Fig. 9g). Taken together, FL imaging not only well tracked EPI and QDs in main organs differentially, but also

could demonstrate targeted delivery of QD@MSN-EPI-Au-PEG-Apt to tumor tissue with excellent intensity. NPS WERE HIGHLY TRACEABLE BY IN VIVO MR AND CT IMAGING The in vivo MR and CT imaging of

C57BL/6 mice bearing HT-29 tumors were performed at 6 and 18 h post-administration of QD@MSN-EPI-Au-PEG and QD@MSN-EPI-Au-PEG-Apt (Fig. 10g–i). The obtained results illuminated higher

differential intensity values in the tumor region of targeted nanocarrier-treated animals compared to non-targeted ones both at 6 and 18 h post-injection (Fig. 10a–f). Apart from the

specific accumulation of QD@MSN-EPI-Au-PEG-Apt in the tumor, which was significantly more than QD@MSN-EPI-Au-PEG, the nonspecific distribution of non-targeted nanocarriers was observed in

heart and liver in both MR and CT imaging, which were reduced after 18 h of injection (Fig. 10b, c, e, f). In accordance with MRI and CT scan encouraging findings, the tendency of targeted

nanocarriers to highly accumulate in the tumor, with less intensity in other organs even at 18 h post-injection, confirmed the active targeting through EpCAM aptamer mediated drug delivery

mechanism. DISCUSSION In recent years, developing theranostic platforms has become a growing interest for more effective treatment and diagnosis of cancer. Nanobiotechnology aims to develop

theranostic nanocarriers with targeting capabilities for colorectal cancer eradication as an emerging concern for human society2. For this purpose, MSN as an ideal biocompatible DDS with

attractive features including easy surface modification and incorporation with other nanoparticles has been widely considered13. More importantly, maximizing drug delivery performance as

well as reducing the adverse side effects of conventional treatments could be addressed by active targeting mechanisms58. Our findings, which are comprehensively discussed in the 

Supplementary Discussion, align with other successful applications of mesoporous silica for incorporating quantum dots, magnetic nanoparticles, gold nanoparticles, silver nanoparticles, and

other nanomaterials13,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100. To the best of our knowledge, this is

the first attempt to use multimodal nanoparticles combining FL and MR properties of GZCIS/ZnS QDs and X-ray attenuation coefficient of Au NPs through silica base backbone. In addition to the

potential of the introduced nanoparticles in the combination therapy of colorectal cancer, their traceability through three imaging modalities can greatly enhance the diagnosis and

theranostic applications. This traceability can improve image registration for clinicians, allowing for better visualization before, during, and after therapies, including surgical or

irradiation procedures. By enabling precise imaging across multiple stages of treatment, it offers valuable insights to clinicians in guiding patient management11. More importantly, the

prepared nanoplatform addresses the conventional therapeutic and diagnostic limitations of single modality by combining several agents together. Overall, the QD@MSN-EPI-Au-PEG-Apt

formulation represents a highly versatile and multifunctional nanoplatform, offering numerous advantages in the field of targeted therapy. Notably, it demonstrates remarkable

biocompatibility, possesses an optimal size (~65 nm) for efficient tumor penetration, facilitates selective delivery of anti-cancer drugs and radiosensitizers through active targeting, and

employs an intelligent cargo release mechanism triggered by acidic pH conditions. Moreover, the hybridized inorganic nanoparticles can potentially undergo various degradation and elimination

mechanisms in the body to offer advantages in addressing long-term toxicity concerns101,102. Nevertheless, one potential obstacle that needs to be addressed is the cost-effective synthesis

of this nanoplatform on a large scale, which may require further optimization and resource management103. In conclusion, the introduced multifunctional DDS, as QD@MSN-EPI-Au-PEG-Apt could

potentially improve therapeutic and diagnostic requirements of CRC patients in decreasing both recurrence and adverse side effects. While these targeted nanocarriers demonstrated no visible

side effects in vivo, further research is necessary to fully understand their fate, elimination process, and potential long-term effects in the body before considering their clinical usage.

METHODS MATERIALS Copper(II) chloride dihydrate (CuCl2·2H2O), indium(III) chloride hydrate (InCl3·H2O), zinc chloride (ZnCl2), gadolinium (III) chloride hexahydrate (GdCl3·6H2O), zinc

acetate dihydrate (Zn(Ac)2.2H2O), sodium oleate (C18H33NaO2), 1-octadecene (ODE), 1-dodecanethiol (DDT), oleylamine, sulfur (S), oleic acid (OA), tetraethylorthosilicate (TEOS), n-cetyl

trimethyl ammonium bromide (CTAB), (3-amino propyl)trimethoxysilane (APTMS), epirubicin (EPI), chloroauric acid (HAuCl4), trisodium citrate, 1-ethyl-3-(3-di-methylaminopropyl) carbodiimide

hydrochloride (EDC) and N-hydroxysuccinimide (NHS) were obtained from Sigma-Aldrich. Heterobifunctional PEG polymer with thiol and carboxylic acid terminal groups (SH–PEG–COOH, Mw: 3500 Da)

was purchased from JenKem (USA). Roswell Park Memorial Institute 1640 (RPMI 1640) medium, fetal bovine serum (FBS), and penicillin/streptomycin were purchased from Gibco (Scotland). Trypsin,

3‑(4,5‑dimethylthiazol‑2‑yl)‑2,5‑diphenyltetrazolium bromide (MTT), and Giemsa were purchased from Tinab Shimi (Iran). FITC-annexin V apoptosis detection kit with propidium iodide (PI) was

obtained from BioLegend (USA). Matrigel® matrix (DLW354263) was obtained from Corning Inc. (USA). The 48 mer EpCAM DNA aptamer (sequence: 5′‐amine CAC TAC AGA GGT TGC GTC TGT CCC ACG TTG TCA

TGG GGG GTT GGC CTG -3′) was synthesized by MicroSynth (Switzerland). DNA marker (50 bp), tris–borate-EDTA (TBE) buffer, and agarose powder were purchased from DENAzist Asia (Iran).

Ethidium bromide was purchased from SinaClon (Iran). Absolute ethanol, chemical reagents, and other solvents were obtained from Merck (Germany). Human colon cancer cell line (HT-29) and

Chinese hamster ovary (CHO) cell line were obtained from Pasteur Institute, Tehran, Iran and cultured in RPMI 1640 medium supplemented with 10% (v/v) FBS at 37 °C containing 5% CO2 in a

humidified incubator. SYNTHESIS OF QUANTUM DOT NANOPARTICLES (GZCIS/ZNS QDS) The synthesis of quantum dot nanoparticles was carried out based on the method described by Guo et al.10. The

first step was the fabrication of metal oleate complexes from chloride minerals according to a previous procedure104,105. Typically, to generate the gadolinium oleate complex, a mixed

solution of GdCl3·6H2O (5 mmol) and sodium oleate (15 mmol) was dissolved in ethanol (20 ml) and distilled water (60 ml). Next, the mixture was stirred under reflux at 70 °C for 4 h. The

product was extracted by adding hexane (20 ml) and washing three times with distilled water in a separating funnel due to the oleate complex hydrophobic structure. Subsequently, the upper

organic layer containing gadolinium oleate was collected and after concentrating by a rotary evaporator, the waxy metal oleate complexes were harvested for QDs fabrication. For GZCIS QDs

fabrication, four metal oleate complexes including Gd(OA)3 (0.4 mmol), Zn(OA)2 (0.1 mmol), Cu(OA)2 (0.1 mmol), and In(OA)3 (0.2 mmol) were mixed with ODE (10 ml) and oleic acid (0.5 ml).

After degassing of the mixture, the reaction temperature was raised to 120 °C under a nitrogen atmosphere. Subsequently, 1 ml DDT was injected into the clear solution leading to a bright

yellow appearance. When the reaction was heated to 205 °C, a solution of sulfur powder (9.7 mg, 0.3 mmol) in 1 ml ODE and 0.5 ml oleylamine was quickly injected into the vessel and kept at

200 °C for 2 h. In the final step, for growth of ZnS shell on GZCIS QDs, 5 ml ODE and 1 ml DDT were added to 4 ml cold GZCIS QDs solution. Afterward, 0.1 mmol Zn(Ac)2 in 1 ml ODE/oleylamine

(v/v, 4/1) was added dropwise and stirred vigorously. The temperature was raised to 220 °C for ZnS shell growth and the above procedure was repeated four times to obtain the most fluorescent

GZCIS/ZnS QDs. The product was quickly cooled to room temperature and precipitated using ethanol and centrifugation. To purify the QDs, washing with ethanol/hexane (v/v, 1/1) was carried

out three times by repeated centrifugation, and ended up by dissolving in chloroform. ENCAPSULATION OF QDS IN MESOPOROUS SILICA NANOPARTICLES (QD@MSN) There are various methods to enhance

the biocompatibility of QDs with silica coating as published previously12. However, the process was adopted based on microemulsion-assisted sol-gel method for silica coating106. First, 25 mg

of GZCIS/ZnS QDs in 1 ml chloroform was mixed with CTAB solution (0.25 M) in 10 ml deionized water. Then the mixture was vortexed vigorously and sonicated for 40 min. When the solution

turned to a semitransparent gel, vigorous stirring at 70 °C was performed to evaporate the chloroform. Afterward, the transparent reddish solution was mixed with 45 ml warm NaOH solution (13

 mM) and kept at 70 °C for 10 min under reflux. Subsequently, after dropwise addition of TEOS (0.75 ml) and ethyl acetate (5 ml), the reaction solution was stirred for 3 h. AMINE

FUNCTIONALIZATION OF SILICA COATED QDS (QD@MSN-NH2) In order to functionalize the silica surface by amine groups, 3 h after formation of bare QD@MSN, 0.15 ml of APTMS was added. The reaction

was stirred for 30 min and cooled down to room temperature. The purified QD@MSN-NH2 NPs were collected after three times washing with ethanol and water by repeating centrifugation (10,000 

_g_ for 20 min) and re-dispersion processes. Finally, the product was freeze-dried for better elimination of solvent and stored at 4 °C. DRUG LOADING PROCEDURE (QD@MSN-NH2-EPI) Typically, 2 

mg of QD@MSN-NH2 were dispersed in 1 ml EPI solution (1 mg/ml) and sonicated for 5 min. Then the mixture was stirred for 24 h at room temperature. Afterward, drug-loaded nanoparticles were

separated by centrifugation (15,000 _g_ for 10 min), and the supernatant containing free EPI was collected. The amount of free EPI was evaluated by absorbance of supernatant and equation of

standard curve (Supplementary Fig. 7) at λ = 480 nm using a UV/Vis spectrophotometer (Eppendorf, Germany). To calculate the encapsulation efficiency (EE%) and drug loading capacity (LC%),

the Eq. 1 and Eq. 2 were used: $${{\mbox{EE}}} \% =\frac{{{\mbox{Total}}} \, {{\mbox{weight}}} \,{{\mbox{of}}} \, {{\mbox{EPI}}}-{{\mbox{Free}}} \, {{\mbox{EPI}}} \,{{\mbox{weight in

supernatant}}}}{{{\mbox{Total}}} \, {{\mbox{weight}}} \, {{\mbox{of}}} \, {{\mbox{EPI}}}}\times 100$$ (1) $${{\mbox{LC}}} \% =\frac{{{\mbox{Total}}} \, {{\mbox{weight}}} \, {{\mbox{of}}} \,

{{\mbox{EPI}}}-{{\mbox{Free}}} \, {{\mbox{EPI}}} \, {{\mbox{weight}}} \, {{\mbox{in}}} \, {{\mbox{supernatant}}}}{{{\mbox{Total}}} \, {{\mbox{weight}}} \, {{\mbox{of}}} \,

{{\mbox{formulation}}}}\times 100$$ (2) CAPPING DRUG LOADED CARRIERS WITH GOLD NANOPARTICLES (QD@MSN-EPI-AU) Gold nanoparticles were used as pH-responsive gatekeepers to cap the pore

entrance of EPI loaded-QD@MSNs via electrostatic interactions between -NH3+ on the MSN surface and the citrate groups of Au NPs. To this aim, we synthesized Au NPs using an optimized

protocol based on citrate reduction method presented by Turkevich in 1951107. Since several parameters including HAuCl4/sodium citrate ratio, pH control, and temperature are important in

final nanoparticle size and stabilization, Au NPs have been synthesized with various properties108. In this regard, 10 ml of 0.5 mM HAuCl4 aqueous solution was heated to boil under constant

stirring. Subsequently, freshly prepared trisodium citrate solution (1 ml; 38.8 mM) was added rapidly to the HAuCl4 solution. During 5 min stirring, the color of the solution turned to gray,

pink, and red which represented Au NPs formation; then the obtained solution was cooled down to room temperature while gently stirring18,109. In the next step, in order to cap the pores of

MSNs, 1 ml of prepared Au NPs were incorporated into 2 mg of EPI loaded-QD@MSNs and stirred at room temperature for 24 h. PEGYLATION AND EPCAM APTAMER CONJUGATION (QD@MSN-EPI-AU-PEG-APT) The

strong covalent bond between Au NPs and thiol groups was conducted by subjecting 6 mg of heterobifunctional PEG (SH–PEG–COOH) to previous suspension of gold-capped nanocarriers

(QD@MSN-EPI-Au) for 24 h at room temperature. Furthermore, EpCAM aptamer was conjugated to non-targeted nanocarriers (QD@MSN-EPI-Au-PEG) via the amine group of aptamer and carboxylic group

of PEG based on EDC/NHS chemistry. In this regard, EDC (3.27 mg) and NHS (1.96 mg) were introduced to the suspension of PEGylated nanocarriers for 30 min to activate the surface carboxylic

acid groups. Subsequently, 20 μl of EpCAM aptamer working solution (10 μM) was added to the suspension and stirred overnight at room temperature. Finally, targeted nanocarriers were

separated from the solution by centrifugation (at 15,000 _g_ for 10 min), washed with deionized water and the supernatant was analyzed spectrophotometrically for drug loading assessments

(Fig. 1a). PHYSICAL CHARACTERIZATION The optical characteristics of prepared nanoparticles were determined using the CARY 100 UV/Vis spectrophotometer (Jasco) and F-2500 fluorescent

spectrophotometer (Hitachi). Magnetic properties of synthesized QD and QD@MSN were analyzed by a vibrating sample magnetometer (VSM; Lake Shore Cryotronics, USA) and MR technique. Dynamic

light scattering (DLS) and electrophoretic light scattering (ELS) techniques were performed to determine particle size and zeta potential of nanocarriers after each modification by the Nano

ZS90 Zeta sizer (Malvern, UK). High resolution-transmission electron microscopy (HR-TEM FEI TECNAI F20, USA), field emission-scanning electron microscopy (FE-SEM; TESCAN MIRA, Czech

Republic), and atomic force microscopy (AFM; BRUKER, USA) were employed to evaluate size and morphology of prepared nanoparticles. Further, in order to collect X‐ray diffraction (XRD)

patterns of the as-synthesized nanoparticles, a Multipurpose-Theta/Theta-high resolution diffractometer (PHILIPS_PW1730, Netherlands) was used. Thermogravimetric analysis (TGA; Q600, USA)

was carried out at a heating rate of 20 °C/min in air to determine the thermal profile of QD, QD@MSN, and QD@MSN-EPI-Au-PEG. Specific surface areas, pore size distribution, and pore volume

of QD@MSN and QD@MSN-EPI-Au were determined at 77 K by Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) methods, using a BELSORP Mini II instrument. Electrophoresis was

performed to prove aptamer conjugation on the surface of QD@MSN-EPI-Au-PEG-Apt. For this purpose, all the samples including DNA ladder, free aptamer, QD@MSN-EPI-Au-PEG, and

QD@MSN-EPI-Au-PEG-Apt were analyzed on a 2% agarose gel containing 0.3 µg/ml ethidium bromide. Fourier transform infrared (FT-IR) spectra were analyzed for nanocarriers in every step of

synthesis to confirm the existence of functional groups using the AVATAR 370 FT-IR spectrometer (Therma Nicolet spectrometer, USA). Finally, elemental compositions of QDs and different NPs

(Gd, In, Cu, Zn, Si, Au, C, O, N, and P) were evaluated by energy-dispersive X-ray spectroscopy (EDX; TESCAN MIRA, Czech Republic). To assess the colloidal stability and polydispersity index

of the final formulation (QD@MSN-EPI-Au-PEG-Apt), incubation experiments were conducted in two media, namely PBS and FBS (30% in PBS, v/v), for 4, 24, and 48 h at 37°C. The size and

polydispersity index (PDI) of the polyplexes were determined using the DLS method at designated time intervals to evaluate their colloidal stability. IN VITRO DRUG RELEASE The gatekeeping

role of Au NPs in the controlled release behavior of EPI was studied in physiologic and acidic conditions. To this aim, 2 mg of capped nanocarriers (QD@MSN-EPI-Au) were dispersed in 1 ml of

release solution (PBS; pH = 7.4 and citrate buffer; pH = 6.4, and 5.4) separately, and incubated at 37 °C with shaking at 100 rpm for 144 h. At predetermined time intervals, 1 ml of each

solution was taken, collected by centrifugation, and replaced with 1 ml of fresh release buffer to maintain a constant volume. Eventually, the supernatants were analyzed by a UV/Vis

spectrophotometer at 480 nm and the mean amount of released EPI was calculated. HEMOLYSIS ASSAY Evaluating the amount of red blood cell (RBC) lysis by nanocarriers was tested by hemolysis

assay. To this aim, the human blood samples from the healthy donors were stabilized by heparin, and RBCs were isolated by centrifugation (1500 _g_ for 10 min at 4 °C). After washing with

cold PBS for blood purification, the pellet was diluted with PBS (1:10). Subsequently, 0.1 ml of RBC suspension was mixed with 0.9 ml PBS/distilled water as negative/positive controls and

0.9 ml dispersion of QD@MSN/QD@MSN-EPI-Au-PEG at different concentrations (12.5 to 400 μg/ml in PBS). All mixtures were shaken at 100 rpm at 37 °C for 4, 12 and 24 h. Finally, the mixtures

were centrifuged (2500 _g_ for 1 min) and the absorbance of released hemoglobin was evaluated at λ = 541 nm by a UV/Vis spectrophotometer. To calculate the hemolysis percentage, Eq. 3 was

used: $$ {{\mbox{Hemolysis}}}\, \% \\ =\frac{{{\mbox{NPs}}} \,{{\mbox{absorbance}}}-{{\mbox{negetive}}} \,{{\mbox{control}}} \,{{\mbox{absorbance}}}}{{{\mbox{positive}}}\, {{\mbox{control}}}

\,{{\mbox{absorbance}}}-{{\mbox{negetive}}} \,{{\mbox{control}}} \,{{\mbox{absorbance}}}}\times 100$$ (3) IN VITRO CELLULAR UPTAKE To investigate the cellular internalization of

nanoparticles quantitatively and qualitatively, cellular uptake was assessed by flow cytometry and fluorescence microscopy, respectively. First, HT-29 and CHO cells (2 × 105 cells/well) were

seeded in 6-well plates and incubated for 24 h. Then, cells were treated with Free EPI, QD@MSN-EPI-Au-PEG, QD@MSN-EPI-Au-PEG-Apt (with equivalent concentration of EPI as 5 μg/ml) and QD@MSN

(equivalent concentration of backbone was 20 μg/ml) for 4 h. Subsequently, for quantitative analysis, after removing culture medium, cells were washed with PBS (1X) and trypsinized,

followed by centrifugation (400 _g_ for 15 min) and resuspension in 300 µl cold PBS (1X). Finally, the fluorescence behavior of different formulations in cells was evaluated by the BD

FACSCalibur flow cytometer in the FL2 channel and results were analyzed by FlowJo V10 software. Moreover, fluorescence microscopy was used to visualize cellular uptake qualitatively.

Briefly, after 4 h treatment with mentioned concentrations, the culture medium was removed and cells were washed with PBS (1X), fixed in 4% paraformaldehyde (w/v) at 4 °C for 20 min, and

stained with DAPI solution (1.5 μg/ml) for 10 min in the dark. Finally, cells were washed with PBS (1X) and observed under a fluorescence microscope (Olympus BX51, Japan). STUDYING CELL

DEATH MECHANISM The cell death mechanism in cancerous cells was determined using the FITC-annexin V apoptosis detection kit and flow cytometry technique. First, HT-29 cells, as

EpCAM-positive for targeted therapy, were seeded in 6 well plates at a density of 2 × 105 cells/well. After 24 h, cells were treated with Free EPI, QD@MSN-EPI-Au-PEG, and

QD@MSN-EPI-Au-PEG-Apt (equivalent concentration of EPI was 5 μg/ml), and untreated cells as a negative control for 4 h. Moreover, to determine radiotherapy effects on cell death, two groups

including complete formulation (QD@MSN-EPI-Au-PEG-Apt) and negative control (untreated cells) were subjected to 3 Gy X-ray, following 4 h treatment and medium exchange (to prevent the

effects of non-internalized formulations). Subsequently, after 24 h incubation at 37 °C, cells were collected and stained with FITC-annexin V kit with PI. Finally, the cell death mechanism

was assessed in six groups utilizing flow cytometry, and the data outputs were analyzed using FlowJo V10 software. The gating strategy employed for the analysis is detailed in Supplementary

Fig. 8. MTT ASSAY MTT assay was used to examine the cytotoxicity of prepared nanoparticles containing epirubicin in vitro. HT-29 as an EpCAM-positive colorectal cancer and CHO as an

EpCAM-negative cell line were seeded (6 × 103 cells/well) separately in 96-well plates. After 24 h incubation in a humidified 5% CO2 incubator at 37 °C, cells were treated in three groups

including Free EPI, QD@MSN-EPI-Au-PEG, and QD@MSN-EPI-Au-PEG-Apt at equivalent concentrations of EPI ranging from 0.39 to 25 µg/ml for 4 h. Then, the treatment culture media were exchanged

with fresh RPMI 1640 containing 10% FBS and further incubated at 37 °C for 24, 48, and 72 h. Afterward, 20 μl of MTT (5 mg/ml in PBS) was added to each well and incubated for another 4 h.

After MTT reduction, the medium was aspirated and 150 µl DMSO was added to dissolve formazan crystals. In the end, the absorbance of the purple product was determined by an ELISA reader

(Awareness Technology, Inc.) at 540 nm. CLONOGENIC ASSAY In order to evaluate the efficacy of combination therapy using targeted nanoparticles carrying EPI as a chemotherapeutic drug, and Au

NP gatekeepers as ideal radiosensitizers, QD@MSN-EPI-Au-PEG-Apt was applied in conjugation with radiotherapy. For this aim, first HT-29 and CHO cells were seeded (6 × 103 cells/well)

separately in 96-well plates. After 24 h incubation, cells were treated, in triplicate, with QD@MSN-EPI-Au-PEG-Apt at different concentrations ranging from 6.25 to 100 µg/ml (equivalent

concentrations of EPI and Au NPs were 1.56–25 µg/ml and 0.625–10 µg/ml, respectively) for 4 h. Subsequently, cells were washed with PBS (1X) and fresh medium was added to ensure that only

internalized NPs could react during irradiation. Hereupon, treated cells were irradiated with different doses of X-ray (3 and 6 Gy) using 6 mV X-rays from a linear accelerator (Artiste,

Siemens, Germany) for 0.95 and 1.44 min, respectively. Afterward, cells were collected, counted, and seeded in 6 well plates with a density of 2 × 103 cells/well and incubated in a

humidified 5% CO2 incubator at 37 °C to proliferate into colonies. After 10 days, the colonies were rinsed with PBS (1X), fixed in methanol (5–8 min), and stained with Giemsa (for 20 min).

Finally, the colonies containing more than 50 cells were counted by OpenCFU-3.9.0 software and the results were confirmed manually. In order to assess the radiosensitization effect, the

plating efficiency (PE), and surviving fraction (SF) were calculated based on Eq. 4 and Eq. 5110,111: $${{\mbox{PE}}}=\frac{{{\mbox{number}}} \,{{\mbox{of}}} \,{{\mbox{colonies}}} \,

{{\mbox{formed}}}}{{{\mbox{number}}} \,{{\mbox{of}}} \,{{\mbox{cells}}}\, {{\mbox{seeded}}}}\times 100$$ (4) $${{\mbox{SF}}}=\frac{{{\mbox{number}}}\, {{\mbox{of}}}\, {{\mbox{colonies}}}\,

{{\mbox{formed}}} \,{{\mbox{after}}} \,{{\mbox{treatment}}}}{{{\mbox{number}}}\, {{\mbox{of}}}\, {{\mbox{cells}}}\, {{\mbox{seeded}}}\times {{\mbox{PE}}}}\times 100$$ (5) IMMUNOSUPPRESSION

AND TUMOR INDUCTION In vivo experiments were performed in accordance with the guidelines approved by the Animal Ethics Committee at Ferdowsi University of Mashhad (IR.UM.REC.1401.040).

Immunosuppression of female C57BL/6 mice (4–6 weeks old and inbred in an animal house at FUM), was performed based on the protocol described previously112,113,114. Initially, administration

of itraconazole (10 mg/kg) via oral route and intraperitoneal injection of cyclosporine (30 mg/kg) were carried out every day for seven days. Afterward, cyclophosphamide (60 mg/kg) was

injected subcutaneously on days 8 and 10. Moreover, all animals were kept in sterile conditions and fed with autoclaved rodent food pellets and water containing co-amoxiclav (0.1 μg/ml)

during the study. The colorectal tumor models were generated by subcutaneous injection of 8 × 106 HT-29 cells (suspended in 1:1; FBS: Matrigel) into the right flank of the immunocompromised

mice18. Within a week, the human tumor xenografts reached approximately 100 mm3 volume. INVESTIGATING THE IN VIVO ANTI-TUMOR EFFICACY C57BL/6 mice with tumor sizes of approximately 100 mm3

were divided into six experimental groups, randomly. Each group (_n_ = 5 per group) was treated intravenously with a single dose of (1) PBS as control, (2) PBS + RT, (3) Free EPI, (4)

QD@MSN-EPI-Au-PEG, (5) QD@MSN-EPI-Au-PEG-Apt, and (6) QD@MSN-EPI-Au-PEG-Apt+RT (equivalent concentrations of EPI and Au NPs were set as 5 mg/kg and 2 mg/kg, respectively). The mice of groups

2 and 6 were irradiated with 3 Gy using 6 mV X-rays from the linear accelerator (Artiste, Siemens, Germany) 24 h post-injection. The tumor volume was calculated based on length × width × 

height/2 formulation by measuring the diameters of the tumor with a digital caliper (Mitutoyo, Japan) every odd day till the fifteenth day after various treatments. On day 16 post-treatment,

the mice were euthanized, and the tumor tissues were isolated. Subsequently, the tissues were fixed in a paraformaldehyde solution (4%), sectioned, and subjected to staining with H&E

for pathological evaluation. Additionally, TUNEL immunofluorescent staining was performed to assess apoptosis. The prepared slides were then examined and photographed using an optical

microscope (Olympus IX70, Japan) and a fluorescence microscope (Olympus BX51, Japan) to capture the respective images. EVALUATION OF IN VIVO BIOSAFETY In order to investigate the in vivo

toxicity of prepared formulations, the body weights of treated mice were measured every other day during the study. On day 16, the mice were euthanized and the major organs including the

heart, lung, spleen, kidney, and liver were isolated, meanwhile, the liver weight of different treatment groups was measured. Subsequently, tissues were fixed in paraformaldehyde solution

(4%), sectioned, and stained with H&E for histological evaluation. The prepared slides were examined and photographed using an optical microscope (Olympus IX70; Japan). EX VIVO FL

IMAGING To investigate the biodistribution of prepared formulations in animal organs as well as their accumulation in tumors, ex vivo fluorescence imaging was employed. Before injection,

colorectal cancer models with 200 mm3 tumor size, were kept without any food but water for 12 h to reduce food fluorescence. Afterward, five experimental groups including PBS, Free EPI,

QD@MSN, QD@MSN-EPI-Au-PEG, and QD@MSN-EPI-Au-PEG-Apt were treated intravenously (equivalent concentration of EPI and QD@MSNs were set as 5 mg/kg and 20 mg/kg, respectively) and sacrificed at

12 and 24 h post-injection. Then, the main organs and tumor tissues were isolated and analyzed using the KODAK IS in vivo imaging system with λexcitation = 450 nm and λemission = 600 nm,

both qualitatively and quantitatively. Furthermore, to further evaluate the efficacy of targeted therapy in vivo, the tumor tissues were sectioned and subsequently stained with the

fluorescent dye DAPI. Images of these stained sections were then captured using a fluorescence microscope. MR & CT IMAGING In order to visualize the biodistribution of nanoparticles

especially their accumulation in tumor sites, MR and CT imaging were used to track the nanoparticles containing Gd and Au. Immunocompromised C57BL/6 mice bearing human HT-29 tumors with 200

mm3 tumor size were employed for each group of non-targeted and targeted nanocarriers in triplicate. At the first step of the study, all animals were categorized into two groups,

anesthetized, fixed with medical tapes and photographed by MRI and CT-scan to minimize artifacts in final pictures. Next, 20 mg/kg of non-targeted and targeted nanocarriers

(QD@MSN-EPI-Au-PEG and QD@MSN-EPI-Au-PEG-Apt) were intravenously injected into the lateral tail vein of mice based on their associated group. After 6 and 18 h of injection, second

photographs were prepared, and differential intensity at the tumor region was analyzed quantitatively. To obtain MR _T__1_-weighted coronal and axial images under a 1.5 T MRI scanner

(Ingenia CX; Philips, Netherlands), the following imaging parameters were used: protocol = turbo field echo (TSE); repetition time (TR) = 752 ms; echo time (TE) = 20 ms; and slice thickness 

= 0.5 mm; resolution = 256 pixel; Number of Averages = 5; Scanning Sequence = GR; Flip Angle = 10; Columns = 224; Pixel Bandwidth = 434; Rows = 224; Echo Number(s) = 1; and Echo Train Length

 = 65. CT images were obtained using a clinical CT scanner (SOMATOM Definition AS; Siemens Medical Systems, Germany) CT scanning parameters were as follows: slice thickness = 2.5 mm; pitch =

 1:1; the tube voltage = 120 kV, the tube current = 200 mA; field of view = 512 × 512, rotation time = 0.75 s and feed rotation = 0.5 mm. The measurements of signal intensity of MRI and

attenuation intensity of CT via Arbitrary unit (AU) and Hounsfield units (HU), respectively, were conducted by DICOM viewer software (Medixant. RadiAnt DICOM Viewer [Software], Version

2020.2. Jul 19, 2020. URL: https://www.radiantviewer.com). STATISTICS AND REPRODUCIBILITY Statistical data analysis was carried out using GraphPad Prism version 9.3.0 (GraphPad Software, San

Diego, CA), based on a minimum of three independent samples. The results are presented as the mean ± standard deviation. Significance testing was performed using One-way single-factor

analysis of variance (ANOVA) to assess the statistical significance of the data. The significance levels were indicated by _p_ values: *<0.05, **<0.01, ***<0.001, and

****<0.0001. All experiments were replicated, and the outcomes were validated. REPORTING SUMMARY Further information on research design is available in the Nature Portfolio Reporting

Summary linked to this article. DATA AVAILABILITY The source data for the figures and tables are given in Supplementary Data, and any remaining information can be obtained from the

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effects against prostate cancer. _Life Sci._ 293, 120272 (2022). Article  CAS  PubMed  Google Scholar  Download references ACKNOWLEDGEMENTS The authors would like to thank Dr. Fatemeh

Delavar Mendi, Dr. Sonia Iranpour, and Miss Niloufar Hoseini Giv for their excellent support. Additionally, we would like to acknowledge Dr. Mahdieh Dayyani, Dr. Shaterzadeh, and colleagues

at Reza Radiotherapy & Oncology Center, Ghaem hospital, and Bu Ali Research Institute for their cooperation and technical support. The schematic figures were created with BioRender.com.

This work was supported by Ferdowsi University of Mashhad, grant number: 57588. AUTHOR INFORMATION AUTHORS AND AFFILIATIONS * Department of Biology, Faculty of Science, Ferdowsi University

of Mashhad, Mashhad, Iran Amir Abrishami, Ahmad Reza Bahrami & Maryam M. Matin * Industrial Biotechnology Research Group, Institute of Biotechnology, Ferdowsi University of Mashhad,

Mashhad, Iran Ahmad Reza Bahrami * Department of Radiology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran Sirous Nekooei * Department of Chemistry, Faculty of

Science, Ferdowsi University of Mashhad, Mashhad, Iran Amir Sh. Saljooghi * Novel Diagnostics and Therapeutics Research Group, Institute of Biotechnology, Ferdowsi University of Mashhad,

Mashhad, Iran Amir Sh. Saljooghi & Maryam M. Matin Authors * Amir Abrishami View author publications You can also search for this author inPubMed Google Scholar * Ahmad Reza Bahrami View

author publications You can also search for this author inPubMed Google Scholar * Sirous Nekooei View author publications You can also search for this author inPubMed Google Scholar * Amir

Sh. Saljooghi View author publications You can also search for this author inPubMed Google Scholar * Maryam M. Matin View author publications You can also search for this author inPubMed 

Google Scholar CONTRIBUTIONS A.A.: Methodology; Formal analysis; Data curation; Investigation; Resources; Software; Visualization; Writing original draft. A.R.B.: Supervision; Validation;

Funding acquisition. S.N.: Methodology; Validation. A.S.S.: Supervision; Validation; Funding acquisition. M.M.M.: Supervision; Validation; Funding acquisition; Review & editing.

CORRESPONDING AUTHORS Correspondence to Amir Sh. Saljooghi or Maryam M. Matin. ETHICS DECLARATIONS COMPETING INTERESTS The authors declare no competing interests. CONSENT FOR PUBLICATION All

authors consent for the manuscript to be published. ETHICS APPROVAL AND CONSENT TO PARTICIPATE The animal experiments were performed in accordance with the guidelines approved by Animal

Ethics Committee at Ferdowsi University of Mashhad (IR.UM.REC.1401.040). PEER REVIEW PEER REVIEW INFORMATION _Communications Biology_ thanks Raviraj Vankayala, Shuangqian Yan and the other,

anonymous, reviewer(s) for their contribution to the peer review of this work. Primary Handling Editors: Huan Bao and Christina Karlsson Rosenthal. A peer review file is available.

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