Insights into tumor size-dependent nanoparticle accumulation using deformed organosilica nanoprobes

Abstract

Silica-based nanoplatforms have revolutionized cancer diagnosis and treatment strategies, but the influence of tumor physiology on the efficacy of these nanoplatforms remains underexplored. This study presents a deformed organosilica fluorescent nanoprobe (CDPF) conjugated with folic acid (FA) and a fluorescent dye (Cy5.5) to explore NP uptake in tumors of varying sizes, mimicking different cancer stages. CDPF exhibited excellent biocompatibility, as demonstrated by cell toxicity tests and blood routine analyses. Using a 4T1 tumor model in female BALB/c mice, we observed a direct correlation between tumor size and CDPF accumulation, with larger tumors showing significantly higher NP uptake. Histological analysis revealed that vascular density and extracellular matrix (ECM) remodeling were key factors in NP accumulation. These findings highlight the critical role of tumor microenvironment dynamics in NP delivery and efficacy, underscoring the need for personalized nanomedicine strategies. The study advances the understanding of NP–tumor interactions and proposes deformed organosilica nanocapsules as promising vehicles for targeted cancer therapy, paving the way for more effective treatment modalities.

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1. Introduction

Cancer remains one of the most formidable challenges in the medical field, characterized by the uncontrolled growth and spread of cells that severely impair the body's normal functions, posing significant health risks and increased mortality.^1,2 Despite advancements in medical technology, cancer continues to claim lives, with approximately 19.3 million new cases and 10 million deaths globally in 2020.³ Beyond the dire health implications, cancer also imposes a substantial financial burden on patients and their families, underscoring the urgent need for effective prevention, diagnosis, and treatment strategies.

The advent of nanomedicine has ushered in a new era of cancer management.^4–7 Leveraging the unique properties of nanoparticles (NPs), researchers have developed innovative diagnostic and therapeutic approaches, offering renewed hope in the battle against cancer. Nanoparticles can be engineered with various sizes, shapes, and surface chemistries to optimize drug delivery directly to tumor sites, enhancing treatment efficacy.^8–11 Among various nanoparticle formulations, mesoporous organic silica nanoparticles (MONs) have emerged as exceptional drug delivery vehicles due to their adjustable porous structure, extensive surface area, facile surface modification, and biocompatibility.^12–16 Mesoporous silica NPs have demonstrated enhanced tumor penetration and accumulation, highlighting their superior potential in cancer diagnosis and treatment.^17,18 However, the path to clinical application of cancer nanomedicine faces obstacles, primarily due to the oversimplified notion of designing “universal” nanoplatforms for tumor treatment, regardless of cancer type or stage.

Tumor growth induces a complex array of dynamic changes within the tissue architecture, markedly altering the cell density, distribution of blood vessels, and composition of the extracellular matrix (ECM).^19–21 As tumors evolve, the resultant pathological landscape is characterized by increasingly distorted blood vessels and compromised perfusion, which obstruct the effective distribution of chemotherapy agents. This leads not only to suboptimal treatment outcomes but also heightens the risk of cancer recurrence.^22,23 The critical role of tumor physiological characteristics in mediating the delivery and efficacy of nanoparticles is pivotal, yet it remains underexplored within the field of nanomedicine.^24,25 There is a pressing need for comprehensive research to decipher the intricate relationships between tumor microenvironment changes and nanoparticle behavior.²⁶ This is particularly important as evidence suggests that the size of the tumor can significantly influence the accumulation of nanomaterials, potentially impacting the delivery and therapeutic efficacy of nanoparticle-based treatments.²⁷ Studies have demonstrated that larger tumors, with their complex interplay of hypoxic areas, enhanced permeability and retention (EPR) effect, provide a conducive environment for the enhanced accumulation of nanoparticles. Conversely, smaller tumors might present less favorable conditions due to their less developed vascular systems and lower interstitial pressures, which can impede nanoparticle penetration and retention.^28,29 These observations underscore the necessity for tailored nanoparticle designs that consider the specific pathological and physiological characteristics of the tumor at various stages of growth. Therefore, further investigation into how nanoparticles interact with tumors of different volumes is crucial. This approach heralds a new era in personalized cancer therapy, where treatment is not only based on genetic profiles but also on the unique physical and biochemical characteristics of the tumor environment.

Herein, we introduced a novel nanoplatform, Cy5.5-DMONs-PEG-FA (CDPF), based on deformed mesoporous organosilica nanocapsules (DMONs) modified with folic acid (FA) and a fluorescent dye (Cy5.5). This nanoplatform was designed to investigate the accumulation of nanoparticles in tumors of varying volumes. Histopathological analysis and blood tests were utilized to evaluate the biocompatibility of CDPF. A 4T1 mouse tumor model was established and employed an in vivo imaging system (IVIS) for analysis to study the accumulation relationship between CDPF and tumor volume. Additionally, histological examinations of tumor sections were conducted to investigate the pathological changes in tumors of different sizes and their impact on nanoparticle distribution and accumulation.

2. Methods

2.1 Materials and reagents

Cetyltrimethyl ammonium bromide (CTAB, AR), tetraethyl orthosilicate (TEOS, 98%), bis[3-(triethoxysilyl)propyl]tetrasulfide (TESPTS, 90%), 1,2-bis(triethoxysilyl)ethane (BTSE, 95%), 1,4-bis (triethoxymethylsilyl)benzene (BTSB, 98%), FA-PEG-MAL (lot#K75PF77K), Cy5.5-MAL (lot#C13766575) were purchased from Shanghai Macklin Biochemical Technology Co., Ltd. The mouse breast cancer 4T1 cells were acquired from Guangzhou Cellcook Biology Company. Female BALB/c mice, aged 5–6 weeks and weighing between 18 and 20 g of a specific pathogen-free (SPF) grade, were sourced from Henan SCBS Company.

2.2 Synthesis of DMONs

The synthesis of deformed mesoporous organosilica nanocapsules (DMONs) was meticulously conducted via a sol–gel process, as previously reported by our research group.³⁰ The procedure began by dissolving 0.48 g of CTAB in a solvent mixture containing 3 mL of ammonia water, 90 mL of anhydrous ethanol, and 375 mL of deionized water. This solution was vigorously stirred at 35 °C to ensure complete dissolution. Subsequently, a mixture composed of 0.375 mL of TEOS, 1.2 mL of BTSE, 0.3 mL of TESPTS, and 0.3 mL of BTSB was introduced into the aforementioned solution. The reaction proceeded for 24 h, after which the resulting product was subjected to centrifugation and triple rinsing with anhydrous ethanol to yield organosilica/CTAB nanocomposite spheres. Following this, 25 mg of the nanocomposite spheres were dispersed in 1 mL of a 2 M sodium hydroxide solution and agitated for 30 minutes at room temperature. The product underwent centrifugation and was washed thrice with deionized water. After resuspending in a solution of 50 μL concentrated hydrochloric acid and 100 mL ethanol, the mixture was stirred at 60 °C for 3 h. This acid treatment was repeated three times to ensure complete removal of the CTAB template, ultimately yielding the desired DMONs.

2.3 Preparation of CDPF

The preparation of Cy5.5 and FA-grafted deformed mesoporous organosilica nanocapsules (CDPF) involves several steps, beginning with the reduction of disulfide bonds within the DMON structure to thiol groups. This process was carried out as reported in the literature.³¹ Initially, 65 mg of DMONs were introduced into a reaction mixture consisting of 0.3 mL of deionized water, 1.1 mL of dioxane, 40 μL of concentrated hydrochloric acid, and 0.1 g of triphenylphosphine. The mixture was maintained at 40 °C for 2 h. After the reaction, the DMONs were washed three times with deionized water to remove residual reactants, resulting in the formation of thiol-functionalized DMONs (DMONs-SH). Following the reduction step, 12 mg of the DMONs-SH were combined with 1.2 mL of N,N-dimethylformamide (DMF) and 1.2 mg of FA-PEG-MAL. This mixture was allowed to react at room temperature for 12 h to facilitate the conjugation of FA to the thiol groups on the DMONs. Subsequently, 1.2 mg of Cy5.5-MAL was added to the reaction mixture, which was then left to react for an additional 12 h. This final step yielded the CDPF, which are DMONs covalently grafted to both FA and the fluorescent dye Cy5.5. As a control, Cy5.5-DMONs-PEG (CDP) was synthesized using the same procedures, except that FA-PEG-MAL was replaced with PEG-MAL.

2.4 Cytotoxicity experiment

The cytotoxicity of DMONs and CDPF was evaluated using 4T1 breast cancer cells. Cells were seeded in 96-well plates at a density of 10 000 cells per well. After a 24 h incubation period to allow for cell attachment and growth, the original culture medium was replaced with fresh media containing various concentrations of DMONs or CDPF (100, 200, 300, 400, and 500 μg mL⁻¹). The cells were incubated for an additional 24 h with these treatments to assess the impact of nanoparticle exposure. Subsequent to this exposure period, 10 μL of CCK-8 reagent was added to each well to evaluate cell viability. The plates were then incubated for a further 2 h to allow for sufficient interaction between the reagent and the cellular metabolic processes. Cell viability was quantitatively assessed by measuring the absorbance at 450 nm using a microplate reader. This assay is based on the reduction of the CCK-8 reagent by cellular dehydrogenases, producing a colorimetric change that correlates with the number of viable cells in each well. The results provide insights into the biocompatibility and potential cytotoxic effects of the nanoparticles at various concentrations.

2.5 Evaluation of cell uptake

To assess the cellular uptake of CDPF, 4T1 breast cancer cells were cultured in 12-well plates at a density of 300 000 cells per well. After allowing sufficient time for cell adhesion, the standard culture medium was replaced with 1 mL of fresh medium containing 200 μg mL⁻¹ of CDPF. The cells were then incubated for various time periods (8, 12, and 24 h) to evaluate the temporal dynamics of nanoparticle uptake. Post-incubation, the cells were gently washed with phosphate-buffered saline (PBS) to remove any unbound nanoparticles. Subsequently, the cells were stained with 4′,6-diamidino-2-phenylindole (DAPI) to label the nuclei, facilitating cellular visualization under a confocal laser scanning microscope (CLSM). This step was crucial for confirming the intracellular localization of the CDPF nanocapsules and for examining their distribution within the cells. Following CLSM imaging, the same cells were enzymatically detached using trypsin, collected, and prepared for flow cytometric analysis. A separate batch of cells that had not been treated with CDPF was used as a control to establish baseline fluorescence and assess autofluorescence.

2.6 Routine blood test in mice

All animal procedures were performed in accordance with the Guidelines for Care and Use of Laboratory Animals of Bengbu Medical University and approved by the Animal Ethics Committee of Bengbu Medical University. To assess the hematological effects of DMONs and CDPF, nine BALB/c mice were randomly assigned to three groups, each receiving an intravenous injection of either saline, DMONs, or CDPF at a dosage of 5 mg kg⁻¹ body weight. Ten days post-administration, blood samples were collected from the orbital vein for comprehensive routine blood analysis. The parameters measured included red blood cell (RBC) count, white blood cell (WBC) count, hemoglobin (HGB) levels, hematocrit (HCT), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), platelet (PLT) count, mean platelet volume (MPV), and other relevant indicators.

2.7 In vivo fluorescence imaging

A 4T1 tumor model was established in female BALB/c mice aged 5–6 weeks and weighing 18–20 g by subcutaneous injection of 5 × 10⁵ tumor cells. Once the tumors reached designated volumes ranging from 0 to 500 mm³, they were categorized into five distinct size groups: 0–100 mm³, 100–200 mm³, 200–300 mm³, 300–400 mm³, and 400–500 mm³. Each mouse received an intravenous injection of 100 μL CDPF solution (5 mg mL⁻¹) via the tail vein. 24 h post-injection, the mice were euthanized, and major organs (heart, liver, spleen, lungs, and kidneys) along with the tumors were harvested and rinsed thoroughly with PBS. Fluorescence imaging of the specimens was performed using an IVIS system to assess the distribution and accumulation of CDPF. Quantitative analysis of the mean fluorescence intensity in each organ and tumor site was conducted to evaluate the biodistribution and tumor-targeting efficacy of the CDPF nanoparticles.

3. Results and discussion

Deformed mesoporous organosilica nanocapsules (DMONs) incorporating ethane groups, phenyl rings, and disulfide bonds were successfully synthesized via a sol–gel process. CTAB served as a structural directing agent, with TEOS, BTSE, TESPTS, and BTSB as co-precursors. Post-synthesis, an etching process with sodium hydroxide and subsequent surfactant removal induced a transformation in the organosilica nanospheres, collapsing their structures into distinctive hollow, bowl-shaped capsules.³¹ Transmission electron microscopy (TEM) images vividly depicted these bowl-shaped DMONs, showcasing diameters ranging approximately between 90 and 100 nm, as detailed in Fig. 1a. Fourier transform infrared spectroscopy (FT-IR) analysis provided a deeper insight into the composition of both DMONs and CDPF, revealing characteristic peaks indicative of successful doping with ethane, phenyl, and disulfide bonds. Fig. 1b highlights these features, including a flexural vibration peak at 1414 cm⁻¹ associated with CH₂–CH₂ groups; a C–H vibration peak at 1157 cm⁻¹ attributed to benzene rings, a C–S vibration peak at 696 cm⁻¹, and Si–O–Si stretching vibrations within the 900–1300 cm⁻¹ range.^30,31 Notably, the presence of an absorption peak at 1556 cm⁻¹ in the CDPF spectrum confirmed the FA modification. Further characterization, as shown in the particle size distribution diagram (Fig. 1c), revealed that CDPF exhibited a hydrodynamic size of approximately 140 nm. This increase in size compared to DMONs can be attributed to the hydration layer surrounding CDPF in solution. The Type IV N₂ adsorption isotherm presented in Fig. 1d confirmed the mesoporous nature of the DMONs, characterized by a significant specific surface area of 852 m² g⁻¹ and an average pore size of 1.76 nm, as determined by Brunauer–Emmett–Teller analysis. These results affirm the successful synthesis of CDPF.

Fig. 1 (a) TEM image of DMONs. The scale bar represents 100 nm. (b) Fourier transform infrared spectroscopy (FT-IR) of DMONs and CDPF. (c) Particle size distribution of CDPF. (d) N₂ adsorption isotherm curve of the DMONs.

FA was introduced into the CDPF to exploit its high affinity for folate receptors, which are overexpressed in many cancer cells. This targeting strategy is designed to enhance the specificity and uptake of nanoparticles by cancer cells, thereby improving therapeutic efficacy and minimizing off-target effects.³² To validate the role of FA in enhancing nanoparticle uptake, additional in vitro studies were conducted. In vitro studies using folate receptor-positive 4T1 breast cancer cells demonstrated significantly higher uptake of CDPF compared to non-targeted nanoparticles (CDP) (Fig. S1, ESI†). To assess the internalization kinetics of CDPF by 4T1 cells, a dosage of 200 μg mL⁻¹ was administered to the cells over discrete time intervals of 8, 12, and 24 h. Confocal laser scanning microscopy (CLSM) enabled real-time visualization of cellular uptake, with the red fluorescence emitted by the Cy5.5 dye serving as a specific indicator for CDPF localization within the cellular milieu. As illustrated in Fig. 2, a progressive augmentation in red fluorescence was observed with increasing incubation time. Specifically, cells treated with CDPF for 12 h exhibited markedly stronger fluorescence compared to those treated for 8 h, with a further enhancement noted in cells exposed for 24 h relative to the 12 h mark. This incremental rise in red fluorescence directly correlates with the heightened internalization of CDPF by 4T1 cells, indicating a time-dependent uptake mechanism. Quantitative analysis of nanoparticle uptake by cells was subsequently performed using flow cytometry. As depicted in Fig. 3(a) and (b), the data revealed that the cellular uptake of CDPF at the 12 h mark was approximately 1.2 times higher than that at 8 h. Moreover, after 24 h of exposure to CDPF, the uptake increased significantly, being 2.1 times higher than at 8 h and 1.8 times higher than at 12 h. These flow cytometry results aligned with the observations from CLSM imaging, affirming a time-dependent increase in CDPF uptake by 4T1 cells. For assessing the biocompatibility of CDPF, 4T1 cells were exposed to various concentrations of DMONs or CDPF for 24 h, followed by viability assessment using a CCK-8 assay. As depicted in Fig. 3(c) and (d), the cell viability remained above 85% across all tested nanoparticle concentrations ranging from 100 μg mL⁻¹ to 500 μg mL⁻¹. Statistical analysis indicated no significant differences in cell viability within this concentration range.

Fig. 2 Time-dependent uptake of CDPF by 4T1 cells visualized via confocal microscopy. The scale bar represents 30 μm.

Fig. 3 (a) The CDPF internalized by 4T1 cells upon different times. (b) Average fluorescence intensity analysis. Percentage of surviving 4T1 cells after 24 h of incubation with DMONs (c) and CDPF (d).

The in vivo biocompatibility of CDPF were meticulously assessed through routine blood tests following intravenous administration into mice via the tail vein. Ten days post-injection, blood samples were carefully collected from the mice via orbital venipuncture to facilitating the analysis of hematological parameters. These parameters, including red blood cell (RBC) count, white blood cell (WBC) count, platelet (PLT) count, mean red blood cell volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), hematocrit (HCT), hemoglobin (HGB), the standard deviation of red blood cell distribution width (RDW-SD), mean platelet volume (MPV), coefficient of variation in red cell distribution width (RDW-CV), and platelet distribution width (PDW), are depicted in Fig. 4. The analysis revealed no statistically significant differences in most tested hematological parameters between the control group, receiving normal saline, and the experimental groups treated with DMONs or CDPF. This indicates a high level of systemic tolerance to the nanoparticles. However, an exception was noted in the WBC count, which experienced an uptick in the groups administered with DMONs or CDPF. This could be attributed to an immunological response elicited by the introduction of these exogenous nanoparticles into the circulatory systems of mice.^33,34

Fig. 4 (a)–(l) Routine blood parameters after intravenous administration of DMONs and CDPF.

To investigate the relationship between tumor size and nanoparticle accumulation, the fluorescence emissions from main organs and tumors were recorded (Fig. 5a). Tumors within the volume range of 0–100 cm³ displayed the faintest fluorescence signals, suggesting a minimal accumulation of the nanoparticles within these smaller tumors. As tumor volumes increased, a significant uptrend in the fluorescence intensity was observed at the tumor. Notably, tumors within the 400–500 cm³ volume range exhibited the most pronounced fluorescence signals, underscoring a substantial enhancement in the accumulation of CDPF nanoparticles. To precisely quantify the biodistribution of CDPF within tumors of varying sizes, we conducted a thorough fluorescence analysis post-intravenous administration into mice bearing tumors of different volumes. The comprehensive analysis, conducted 24 h post-injection, focused on recording the fluorescence signals emitted from both vital organs and the tumors themselves. Our findings revealed a direct correlation between tumor volume and CDPF accumulation. Specifically, the fluorescence intensity in tumors sized 100–200 mm³ was observed to be 1.62 times greater than that in the smallest tumor group (0–100 mm³). This trend of increasing nanoparticle accumulation continued in a volume-dependent manner, with intensities for tumor groups sized 200–300 mm³, 300–400 mm³, and 400–500 mm³ being 2.82, 3.43, and 4.35 times greater, respectively, compared to the baseline (0–100 mm³ group) (Fig. 5b). Such incremental intensification of fluorescence signals not only underscores the enhanced permeability and retention effect observed with increasing tumor size but also highlights the efficacy of CDPF nanocapsules in targeting and accumulating within tumor tissues. This observation indicates that the early stages of tumor growth might present challenges for effective nanoparticle accumulation, potentially due to limited vascularization or other physiological barriers. This trend suggests that larger tumors, possibly due to their enhanced vascular permeability and the enhanced permeability and retention (EPR) effects, provide a more conducive environment for the accumulation of such nanocapsules. These findings illuminate the critical influence of tumor size on the biodistribution and localization of therapeutic nanoparticles. We also observed variations in fluorescence intensity in normal tissues, such as the lungs and across different tumor size groups. Specifically, the lung accumulation in group V (tumors sized 400–500 mm³) was significantly lower than in other groups. This can be attributed to the size-dependent biodistribution of nanoparticles, where larger tumors with EPR effects sequester more nanoparticles, reducing their relative distribution to other organs. Additionally, systemic clearance mechanisms may also contribute to this observation. The significantly low fluorescence intensity in the middle image of group III (tumors sized 200–300 mm³) could be due to individual biological variability among mice and slight technical variations during nanoparticle injection and imaging. These factors highlight the importance of considering both biological and technical variability in nanoparticle biodistribution studies.²⁶ Our findings underline the complex interactions between tumor size, nanoparticle distribution, and normal tissue accumulation, which are critical for optimizing nanoparticle-based cancer therapies.

Fig. 5 (a) IVIS images of mouse vital organs and tumor sites. From top to bottom, left: heart, liver, spleen; right: lung, kidney, tumor. (b) Diagram showing the mean fluorescence intensity at the tumor. Group I: 0–100 mm³, II: 100–200 mm³, III: 200–300 mm³, IV: 300–400 mm³, V: 400–500 mm³.

To elucidate the mechanisms underlying the varying uptake of deformed organosilica nanocapsules by tumors of different sizes, an in-depth histological analysis was performed on tissue sections from mice tumors across varying volume categories. Utilizing CD31 antibodies for staining, the analysis provided a visual representation of the tumor vasculature (Fig. 6a), revealing a direct correlation between tumor size and vascular complexity. Initial stages of tumor development were characterized by a sparse network of larger vessels. However, as tumors expanded, a notable proliferation of smaller, newly formed vessels was observed, indicating an increase in blood vessel density alongside tumor growth. This enhanced vascularity is posited to facilitate the greater accumulation of nanomaterials at the tumor site, as evidenced by the corresponding increase in CDPF fluorescence intensity with tumor volume. This phenomenon suggests that the improved vascular network in larger tumors improves the delivery efficiency of nanoparticles through the bloodstream. Further insight was gained through Movat pentachrome staining (Fig. 6b), which accentuated the cell nucleus and various extracellular matrix (ECM) components such as proteoglycans, mucosaccharides, and collagens. This staining technique unveiled an increase in proteoglycans and mucosaccharides concurrent with tumor progression. Moreover, the ECM appeared to undergo restructuring with tumor expansion, becoming more amorphous and displaying components that enshrouded tumor blood vessels. This remodeling of the ECM, particularly with the accumulation of specific ECM components at the tumor site, is likely a significant factor facilitating the entry and accumulation of nanoparticles into tumor cells. Sirius red staining, specifically targeting type I collagen (Fig. 6c), highlighted a gradual decrease in collagen fibers as tumors grew. This reduction contributes to a weakened ECM structural integrity, favoring the dispersal and accumulation of nanomaterials within the tumor environment. Collectively, these findings underscore the critical role of tumor-associated vascular and ECM remodeling in modulating the uptake and distribution of deformed organosilica nanocapsules. In this study, we have focused on silica nanoparticles due to their unique properties and extensive application in biomedical research.³⁵ While our findings provide valuable insights into the accumulation and distribution of silica nanoparticles in tumors of varying sizes, we recognize that the behavior of organic and lipid nanoparticles may differ.^36,37 Future research should investigate these other types of nanoparticles to assess the universality of our conclusions and further advance the field of nanoparticle-based tumor therapy.

Fig. 6 (a) Mouse tumor DAPI- and CD31-stained sections from different tumor volume groups. (b) Movat pentachrome staining of tumor sections. (c) Sirius red staining of tumor sections. The scale bar represents 50 μm. Group I: 0–100 mm³, II: 100–200 mm³, III: 200–300 mm³, IV: 300–400 mm³, V: 400–500 mm³.

In this study, we investigated the cellular uptake and tumor accumulation of deformed organosilica nanoprobe (CDPF) labeled with FA and Cy5.5. Our findings are consistent with previous reports on mesoporous organosilica nanocapsules, which have demonstrated efficient cellular uptake and significant tumor accumulation due to the EPR effect.³⁸ Previous studies, such as that of Teng et al., have reported that deformable hollow mesoporous organosilica nanocapsules exhibit high cellular internalization due to their large surface area and functionalizability.³¹ Our results align with these findings, showing that CDPF nanocapsules are effectively taken up by 4T1 breast cancer cells, with the addition of FA further enhancing this uptake via folate receptor-mediated endocytosis. Similarly, the EPR effect has been well-documented as a mechanism for the preferential accumulation of mesoporous organosilica nanocapsules in tumor tissues. Zhang et al. highlighted the role of the EPR effect in facilitating nanoparticle accumulation in tumors.³⁹ Our study extends this understanding by demonstrating that larger tumors, with their increased vascularization and ECM remodeling, show significantly higher nanoparticle uptake compared to smaller tumors. This size-dependent accumulation underscores the importance of considering tumor microenvironment dynamics in the design and application of nanoparticle-based therapies.⁴⁰ By comparing our results with these previous reports, we provide a comprehensive understanding of the factors influencing the cellular uptake and tumor accumulation of mesoporous organosilica nanocapsules, thereby advancing the field of personalized nanomedicine.

4. Conclusions

In this study, we designed, synthesized, and characterized the deformed organosilica nanoprobe (CDPF) labeled with FA and Cy5.5 to investigate their accumulation in tumors of varying sizes. Our results reveal a positive correlation between tumor volume and CDPF accumulation, with larger tumors showing significantly higher nanoparticle uptake. This trend was attributed to the enhanced vascularization and extracellular matrix (ECM) remodeling observed in larger tumors, which facilitate the EPR effect and improve nanoparticle retention. The comprehensive biocompatibility assessment, including cytotoxicity assays and routine blood tests, demonstrated the promising safety profile of CDPF, supporting its potential for clinical application. Cellular uptake assays confirmed the efficient internalization of CDPF by 4T1 cells, further validating its suitability for targeted cancer therapy. These findings underscore the critical role of tumor microenvironment dynamics in influencing nanoparticle efficacy and highlight the necessity for personalized nanomedicine strategies. By considering tumor-specific characteristics, such as size and vascularization, it is possible to enhance the design and performance of nanoparticle-based therapies, ultimately improving treatment outcomes for cancer patients. The insights gained from this study can pave the way for more effective and personalized cancer treatment modalities. Specifically, the ability to tailor nanoparticle designs to the unique physical and biochemical characteristics of the tumor microenvironment at different growth stages could significantly enhance therapeutic efficacy. Additionally, the findings suggest that larger tumors, with their enhanced vascular permeability, may be more amenable to nanoparticle-based treatments, which could help in making informed clinical decisions regarding the timing and type of nanoparticle therapy. Future studies should explore adaptive nanoparticle systems capable of responding to the dynamic changes within the tumor microenvironment, as well as investigate the interactions between nanoparticles and other cellular components within tumors. Such efforts will leverage the full potential of nanomedicine, ultimately advancing the field of personalized cancer therapy.

Data availability

The data that support the plots in this paper and other findings of this study are available from the corresponding authors upon reasonable request.

Conflicts of interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

This work was supported by the Special Support Program for Innovation and Entrepreneurship Leading Talents of Anhui Province (T000708), the 512 Talent Cultivation Program of Bengbu Medical College (no. by51201101), the Department of Education of Anhui Province (KJ2021A0732), the Open Research Fund of State Key Laboratory of Organic Electronics and Information Displays (SKL2023002), the Science and Technology Innovation Guidance Project of Bengbu City (20220127), and the College Students’ Innovation and Entrepreneurship Training Program (202210367075 and S202310367061).

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Footnote

† Electronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d4qm00482e

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