Fabrication of high specificity hollow mesoporous silica nanoparticles assisted by Eudragit for targeted drug delivery

Silica nanoparticle design for colorectal cancer treatment: Recent progress and clinical potential

Colorectal cancer (CRC) is the third most common cancer worldwide and the second most common cause of cancer death. Nanotherapies are able to selectively target the delivery of cancer therapeutics, thus improving overall antitumor efficiency and reducing conventional chemotherapy side effects. Mesoporous silica nanoparticles (MSNs) have attracted the attention of many researchers due to their remarkable advantages and biosafety. We offer insights into the recent advances of MSNs in CRC treatment and their potential clinical application value.

Targeted delivery of elesclomol using a magnetic mesoporous platform improves prostate cancer treatment both in vitro and in vivo

BACKGROUND

To improve the anticancer properties of elesclomol (ELC), targeted theranostic nanoparticles (NPs; APT-PEG-Au-MMNPs@ELC) were designed to increase the selectivity of the drug delivery system (DDS).

MATERIALS AND METHODS

ELC was synthesized and entrapped in the open porous structure of magnetic mesoporous silica nanoparticles (MMNPs). The pore entrance of MMNPs was then blocked using gold gatekeepers. Finally, the external surfaces of the particles were grafted with functional polyethylene glycol (PEG) and EpCAM aptamer to generate biocompatible and targeted NPs. In the next step, the physicochemical properties of prepared NPs were fully evaluated and their anticancer potential was evaluated both in vitro and in vivo.

RESULTS

The targeted NPs were successfully synthesized with a final size diameter of 81.13 ± 7.41 nm. The results indicated a pH-dependent release pattern, which sustained for 72 h despite an initial rapid release. Upon exposure to APT-PEG-Au-MMNPs@ELC, higher cytotoxicity was observed in human prostate cancer cells (PC-3) as compared with control Chinese hamster ovary (CHO) cells, indicating higher specificity of targeted NPs against EpCAM-positive cancerous cells. Moreover, APT-PEG-Au-MMNPs@ELC could induce apoptosis in PC-3 cells. In vivo results on a PC-3 xenograft tumor model demonstrated that targeted NPs could significantly inhibit tumor growth and diminish severe side effects of ELC, compared to the free drug.

CONCLUSION

Collectively, APT-PEG-Au-MMNPs@ELC could be considered a promising theranostic platform for the targeted delivery of ELC to improve its therapeutic effects in prostate cancer.

Recent Advances in Mesoporous Silica Nanoparticle-Mediated Drug Delivery for Breast Cancer Treatment

Breast cancer (BC) currently occupies the second rank in cancer-related global female deaths. Although consistent awareness and improved diagnosis have reduced mortality in recent years, late diagnosis and resistant response still limit the therapeutic efficacy of chemotherapeutic drugs (CDs), leading to relapse with consequent invasion and metastasis. Treatment with CDs is indeed well-versed but it is badly curtailed with accompanying side effects and inadequacies of site-specific drug delivery. As a result, drug carriers ensuring stealth delivery and sustained drug release with improved pharmacokinetics and biodistribution are urgently needed. Core-shell mesoporous silica nanoparticles (MSNPs) have recently been a cornerstone in this context, attributed to their high surface area, low density, robust functionalization, high drug loading capacity, size-shape-controlled functioning, and homogeneous shell architecture, enabling stealth drug delivery. Recent interest in using MSNPs as drug delivery vehicles has been due to their functionalization and size-shape-driven versatilities. With such insights, this article focuses on the preparation methods and drug delivery mechanisms of MSNPs, before discussing their emerging utility in BC treatment. The information compiled herein could consolidate the database for using inorganic nanoparticles (NPs) as BC drug delivery vehicles in terms of design, application and resolving post-therapy complications.

Controlled-release of apatinib for targeted inhibition of osteosarcoma by supramolecular nanovalve-modified mesoporous silica

Targeted delivery of antitumor drugs has been recognized as a promising therapeutic modality to improve treatment efficacy, reduce the toxic side effects and inhibit tumor recurrence. In this study, based on the high biocompatibility, large specific surface area, and easy surface modification of small-sized hollow mesoporous silica nanoparticles β-cyclodextrin (β-CD)-benzimidazole (BM) supramolecular nanovalve, together with bone-targeted alendronate sodium (ALN) were constructed on the surface of small-sized HMSNs. The drug loading capacity and efficiency of apatinib (Apa) in HMSNs/BM-Apa-CD-PEG-ALN (HACA) were 65% and 25%, respectively. More importantly, HACA nanoparticles can release the antitumor drug Apa efficiently compared with non-targeted HMSNs nanoparticles in the acidic microenvironment of the tumor. In vitro studies showed that HACA nanoparticles exhibited the most potent cytotoxicity in osteosarcoma cells (143B cells) and significantly reduced cell proliferation, migration and invasion. Therefore, the drug-efficient release of antitumor effect of HACA nanoparticles is a promising way to treat osteosarcoma.

ROS- and pH-Responsive Polydopamine Functionalized Ti3C2Tx MXene-Based Nanoparticles as Drug Delivery Nanocarriers with High Antibacterial Activity

Premature drug release and poor controllability is a challenge in the practical application of tumor therapy, which may lead to poor chemotherapy efficacy and severe adverse effects. In this study, a reactive oxygen species (ROS)-cleavable nanoparticle system (MXene-TK-DOX@PDA) was designed for effective chemotherapy drug delivery and antibacterial applications. Doxorubicin (DOX) was conjugated to the surface of (3-aminopropyl)triethoxysilane (APTES)-functionalized MXene via an ROS-cleavable diacetoxyl thioketal (TK) linkage. Subsequently, the surfaces of the MXene nanosheets were coated with pH-responsive polydopamine (PDA) as a gatekeeper. PDA endowed the MXene-TK-DOX@PDA nanoparticles with superior biocompatibility and stability. The MXene-TK-DOX@PDA nanoparticles had an ultrathin planar structure and a small lateral size of approximately 180 nm. The as-synthesized nanoparticles demonstrated outstanding photothermal conversion efficiency, superior photothermal stability, and a remarkable extinction coefficient (23.3 L g^-1 cm^-1 at 808 nm). DOX exhibited both efficient ROS-responsive and pH-responsive release performance from MXene-TK-DOX@PDA nanoparticles due to the cleavage of the thioketal linker. In addition, MXene-TK-DOX@PDA nanoparticles displayed high antibacterial activity against both Gram-negative Escherichia coli (E. coli) and Gram-positive Bacillus subtilis (B. subtilis) within 5 h. Taken together, we hope that MXene-TK-DOX@PDA nanoparticles will enrich the drug delivery system and significantly expand their applications in the biomedical field.

Dual (pH- and ROS-) Responsive Antibacterial MXene-Based Nanocarrier for Drug Delivery

In this study, a novel MXene (Ti₃C₂T_x)-based nanocarrier was developed for drug delivery. MXene nanosheets were functionalized with 3, 3'-diselanediyldipropionic acid (DSeDPA), followed by grafting doxorubicin (DOX) as a model drug to the surface of functionalized MXene nanosheets (MXene-Se-DOX). The nanosheets were characterized using scanning electron microscopy, atomic force microscopy (AFM), transmission electron microscopy, energy-dispersive X-ray spectroscopy (EDX), nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and zeta potential techniques. The drug-loading capacity (17.95%) and encapsulation efficiency (41.66%) were determined using ultraviolet-visible spectroscopy. The lateral size and thickness of the MXene nanosheets measured using AFM were 200 nm and 1.5 nm, respectively. The drug release behavior of the MXene-Se-DOX nanosheets was evaluated under different medium conditions, and the nanosheets demonstrated outstanding dual (reactive oxygen species (ROS)- and pH-) responsive properties. Furthermore, the MXene-Se-DOX nanosheets exhibited excellent antibacterial activity against both Gram-negative E. coli and Gram-positive B. subtilis.

Strategies for drug targeting in pancreatic cancer

BACKGROUND

Pancreatic cancer is expected to replace lung cancer as the second greatest cause of cancer mortality by 2025. It has been a particularly the most lethal kind of cancer.

OBJECTIVE

Despite the new innovations, research, and improvements in drug design; there are many hurdles limiting their therapeutic applications such as intrinsic resistance to chemotherapeutics, inability to deliver a sufficient concentration of drug to the target site, lack of effectiveness of drug delivery systems. These are the major contributing factors to limit the treatment. So, the main objective is to overcome these types of problems by nanotechnology and ligand conjugation approach to achieve targeted drug delivery.

METHOD

Nanotechnology has emerged as a major approach to develop cancer treatment. Regardless of the severity, there are several issues that restrict the therapeutic impact, including inadequate transport across biological barriers, limited cellular absorption, degradation, and faster clearance.

RESULT

Targeted drug delivery may overcome these obstacles by binding a natural ligand to the surface of nanocarriers, which enhances the drug's capacity to release at the desired site and minimizes adverse effects.

CONCLUSION

This study will investigate the possible outcomes of targeted therapeutic agent delivery in the treatment of pancreatic cancer, as well as the limitations and future prospects.

Improving anti-cancer drug delivery performance of magnetic mesoporous silica nanocarriers for more efficient colorectal cancer therapy

BACKGROUND

Improving anti-cancer drug delivery performance can be achieved through designing smart and targeted drug delivery systems (DDSs). For this aim, it is important to evaluate overexpressed biomarkers in the tumor microenvironment (TME) for optimizing DDSs.

MATERIALS AND METHODS

Herein, we designed a novel DDS based on magnetic mesoporous silica core-shell nanoparticles (SPION@MSNs) in which release of doxorubicin (DOX) at the physiologic pH was blocked with gold gatekeepers. In this platform, we conjugated heterofunctional polyethylene glycol (PEG) onto the outer surface of nanocarriers to increase their biocompatibility. At the final stage, an epithelial cell adhesion molecule (EpCAM) aptamer as an active targeting moiety was covalently attached (Apt-PEG-Au@NPs-DOX) for selective drug delivery to colorectal cancer (CRC) cells. The physicochemical properties of non-targeted and targeted nanocarriers were fully characterized. The anti-cancer activity, cellular internalization, and then the cell death mechanism of prepared nanocarriers were determined and compared in vitro. Finally, tumor inhibitory effects, biodistribution and possible side effects of the nanocarriers were evaluated in immunocompromised C57BL/6 mice bearing human HT-29 tumors.

RESULTS

Nanocarriers were successfully synthesized with a mean final size diameter of 58.22 ± 8.54 nm. Higher cytotoxicity and cellular uptake of targeted nanocarriers were shown in the EpCAM-positive HT-29 cells as compared to the EpCAM-negative CHO cells, indicating the efficacy of aptamer as a targeting agent. In vivo results in a humanized mouse model showed that targeted nanocarriers could effectively increase DOX accumulation in the tumor site, inhibit tumor growth, and reduce the adverse side effects.

CONCLUSION

These results suggest that corporation of a magnetic core, gold gatekeeper, PEG and aptamer can strongly improve drug delivery performance and provide a theranostic DDS for efficient CRC therapy.

The Application of Inorganic Nanoparticles in Molecular Targeted Cancer Therapy: EGFR Targeting

Epidermal growth factor receptor (EGFR) is an anticancer drug target for a number of cancers, such as non-small cell lung cancer. However, unsatisfying treatment effects, terrible side-effects, and development of drug resistance are current insurmountable challenges of EGFR targeting treatments for cancers. With the advancement of nanotechnology, an increasing number of inorganic nanomaterials are applied in EGFR-mediated therapy to improve those limitations and further potentiate the efficacy of molecular targeted cancer therapy. Given their facile preparation, easy modification, and biosecurity, inorganic nanoparticles (iNPs) have been extensively explored in cancer treatments to date. This review presents an overview of the application of some typical metal nanoparticles and nonmetallic nanoparticles in EGFR-targeted therapy, then discusses and summarizes the relevant advantages. Moreover, we also highlight future perspectives regarding their remaining issues. We hope these discussions inspire future research on EGFR-targeted iNPs.

Thiolated polymer nanocarrier reinforced with glycyrrhetinic acid for targeted delivery of 5-fluorouracil in hepatocellular carcinoma

The present work investigates the targeting efficacy of a novel thiolated polymer-based nanocomposite reinforced with glycyrrhetinic acid (GA) and loaded with 5-fluorouracil in hepatocellular carcinoma (HCC). The thiolated polymers were synthesized by EDAC-mediated conjugation reactions and lyophilization. The nanoparticles were prepared by solvent diffusion and high-pressure homogenization method. The prepared nanocomposite was characterized by Fourier transform infrared (FTIR) radiation, x-ray diffraction (XRD), dynamic light scattering (DLS), scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. Pharmacological evaluation of the formulation was carried out on a rat model of diethylnitrosamine (DEN), and carbon tetrachloride (CCl₄)-induced HCC and MTT assay was carried out with HEP-G2 cell line. In silico studies were conducted to investigate the probable mechanistic pathway of the nanocomposite. FTIR and XRD analysis indicated the successful thiolation of the polymers and confirmed the formation of the nanocomposite without any incompatibilities. DLS, SEM/EDX and AFM characterization confirmed that the nanoparticles were within the nano-size range. MTT assay implied the cytotoxic nature of the nanocomposite against hepatic carcinoma cells. The in vivo study revealed that serum SGOT, SGPT, ALP, GGT and total bilirubin levels were significantly reduced, in comparison with disease control and the result was confirmed by histopathology studies. The results of the HPLC analysis of liver homogenate confirmed the liver targeting ability of the nanocomposite. In silico studies exhibited significant binding affinity of GA and thiolated Eudragit towards liver homolog receptor-1 (LRH-1) suggesting that the developed nanocomposite could be a potential material for the treatment of HCC.

Tailored Mesoporous Inorganic Biomaterials: Assembly, Functionalization, and Drug Delivery Engineering

Infectious or immune diseases have caused serious threat to human health due to their complexity and specificity, and emerging drug delivery systems (DDSs) have evolved into the most promising therapeutic strategy for drug-targeted therapy. Various mesoporous biomaterials are exploited and applied as efficient nanocarriers to loading drugs by virtue of their large surface area, high porosity, and prominent biocompatibility. Nanosized mesoporous nanocarriers show great potential in biomedical research, and it has become the research hotspot in the interdisciplinary field. Herein, recent progress and assembly mechanisms on mesoporous inorganic biomaterials (e.g., silica, carbon, metal oxide) are summarized systematically, and typical functionalization methods (i.e., hybridization, polymerization, and doping) for nanocarriers are also discussed in depth. Particularly, structure-activity relationship and the effect of physicochemical parameters of mesoporous biomaterials, including morphologies (e.g., hollow, core-shell), pore textures (e.g., pore size, pore volume), and surface features (e.g., roughness and hydrophilic/hydrophobic) in DDS application are overviewed and elucidated in detail. As one of the important development directions, advanced stimuli-responsive DDSs (e.g., pH, temperature, redox, ultrasound, light, magnetic field) are highlighted. Finally, the prospect of mesoporous biomaterials in disease therapeutics is stated, and it will open a new spring for the development of mesoporous nanocarriers.

Aerosol-Assisted Synthesis of Tailor-Made Hollow Mesoporous Silica Microspheres for Controlled Release of Antibacterial and Anticancer Agents

Hollow mesoporous silica microsphere (HMSM) particles are one of the most promising vehicles for efficient drug delivery owing to their large hollow interior cavity for drug loading and the permeable mesoporous shell for controlled drug release. Here, we report an easily controllable aerosol-based approach to produce HMSM particles by continuous spray-drying of colloidal silica nanoparticles and Eudragit/Triton X100 composite (EUT) nanospheres as templates, followed by template removal. Importantly, the internal structure of the hollow cavity and the external morphology and the porosity of the mesoporous shell can be tuned to a certain extent by adjusting the experimental conditions (i.e., silica to EUT mass ratio and particle size of silica nanoparticles) to optimize the drug loading capacity and the controlled-release properties. Then, the application of aerosol-synthesized HMSM particles in controlled drug delivery was investigated by loading amoxicillin as an antibiotic compound with high entrapment efficiency (up to 46%). Furthermore, to improve the biocompatibility of the amoxicillin-loaded HMSM particles, their surfaces were functionalized with poly(allylamine hydrochloride) and alginate as biocompatible polymers via the layer-by-layer assembly. The resulting particles were evaluated toward Escherichia coli (Gram-negative) bacteria and indicated the bacterial inhibition up to 90% in less than 2 h. Finally, we explored the versatility of HMSMs as drug carriers for pancreatic cancer treatment. Because the pH value of the extracellular medium in pancreatic tumors is lower than that of the healthy tissue, chitosan as a pH-sensitive gatekeeper was grafted to the HMSM surface and then loaded with a pro-apoptotic NCL antagonist agent (N6L) as an anticancer drug. The obtained particles exhibited pH-responsive drug releases and excellent anticancer activities with inhibition of cancer cell growth up to 60%.

Sterically Stabilised Polymeric Mesoporous Silica Nanoparticles Improve Doxorubicin Efficiency: Tailored Cancer Therapy

The fruition, commercialisation and clinical application combining nano-engineering, nanomedicine and material science for utilisation in drug delivery is becoming a reality. The successful integration of nanomaterial in nanotherapeutics requires their critical development to ensure physiological and biological compatibility. Mesoporous silica nanoparticles (MSNs) are attractive nanocarriers due to their biodegradable, biocompatible, and relative malleable porous frameworks that can be functionalized for enhanced targeting and delivery in a variety of disease models. The optimal formulation of an MSN with polyethylene glycol (2% and 5%) and chitosan was undertaken, to produce sterically stabilized, hydrophilic MSNs, capable of efficient loading and delivery of the hydrophobic anti-neoplastic drug, doxorubicin (DOX). The pH-sensitive release kinetics of DOX, together with the anticancer, apoptosis and cell-cycle activities of DOX-loaded MSNs in selected cancer cell lines were evaluated. MSNs of 36-60 nm in size, with a pore diameter of 9.8 nm, and a cumulative surface area of 710.36 m²/g were produced. The 2% pegylated MSN formulation (PCMSN) had the highest DOX loading capacity (0.98 mgdox/mgmsn), and a sustained release profile over 72 h. Pegylated-drug nanoconjugates were effective at a concentration range between 20-50 μg/mL, inducing apoptosis in cancer cells, and affirming their potential as effective drug delivery vehicles.

Present Scenario of Bioconjugates in Cancer Therapy: A Review

Cancer is one of the deadliest diseases and poses a risk to people all over the world. Surgery, chemo, and radiation therapy have been the only options available until today to combat this major problem. Chemotherapeutic drugs have been used for treatment for more than 50 years. Unfortunately, these drugs have inherent cytotoxicities and tumor cells have started inducing resistance against these drugs. Other common techniques such as surgery and radiotherapy have their own drawbacks. Therefore, such techniques are incompetent tools to alleviate the disease efficiently without any adverse effects. This scenario has inspired researchers to develop alternative techniques with enhanced therapeutic effects and minimal side effects. Such techniques include targeted therapy, liposomal therapy, hormonal therapy, and immunotherapy, etc. However, these therapies are expensive and not effective enough. Furthermore, researchers have conjugated therapeutic agents or drugs with different molecules, delivery vectors, and/or imaging modalities to combat such problems and enhance the therapeutic effect. This conjugation technique has led to the development of bioconjugation therapy, in which at least one molecule is of biological origin. These bioconjugates are the new therapeutic strategies, having prospective synergistic antitumor effects and have potency to overcome the complications being produced by chemo drugs. Herein, we provide an overview of various bioconjugates developed so far, as well as their classification, characteristics, and targeting approach for cancer. Additionally, the most popular nanostructures based on their organic or inorganic origin (metallic, magnetic, polymeric nanoparticles, dendrimers, and silica nanoparticles) characterized as nanocarriers are also discussed. Moreover, we hope that this review will provide inspiration for researchers to develop better bioconjugates as therapeutic agents.

Polymeric Mesoporous Silica Nanoparticles for Enhanced Delivery of 5-Fluorouracil In Vitro

There is a need for the improvement of conventional cancer treatment strategies by incorporation of targeted and non-invasive procedures aimed to reduce side-effects, drug resistance, and recurrent metastases. The anti-cancer drug, 5-fluorouracil (5-FU), is linked to a variety of induced-systemic toxicities due to its lack of specificity and potent administration regimens, necessitating the development of delivery vehicles that can enhance its therapeutic potential, while minimizing associated side-effects. Polymeric mesoporous silica nanoparticles (MSNs) have gained popularity as delivery vehicles due to their high loading capacities, biocompatibility, and good pharmacokinetics. MSNs produced in this study were functionalized with the biocompatible polymers, chitosan, and poly(ethylene)glycol to produce monodisperse NPs of 36-65 nm, with a large surface area of 710.36 m2/g, large pore volume, diameter spanning 9.8 nm, and a favorable zeta potential allowing for stability and enhanced uptake of 5-FU. Significant drug loading (0.15-0.18 mg5FU/mgmsn), controlled release profiles (15-65%) over 72 hours, and cell specific cytotoxicity in cancer cells (Caco-2, MCF-7, and HeLa) with reduced cell viability (≥50%) over the non-cancer (HEK293) cells were established. Overall, these 5FU-MSN formulations have been shown to be safe and effective delivery systems in vitro, with potential for in vivo applications.

Evaluation of the in vitro Antitumor Activity of Nanostructured Cyclotides in Polymers of Eudragit® L 100-55 and RS 30 D

Background:

Cancer is a major cause of mortality and morbidity and given the limitations of many current cancer drugs, there is great need to discover and develop novel treatments. An alternative to the conventional drug discovery path is to exploit new classes of natural compounds such as cyclotides. This peptide family is characterized by linked C- and N-termini and a structural fold called the cyclic cystine knot (CCK). The CCK fold is responsible for the exceptional enzymatic, chemical and thermal stability of cyclotides.

Methods:

In the present study, an alternative to traditional cancer treatments, involving new nanomaterials and nanocarriers allowing efficient cyclotide delivery, is proposed. Using the polymers Eudragit® L 100-55 and RS 30 D, the cyclotides kalata B2 and parigidin-br1 (PBR1) were nanocapsulated, and nanoparticles 91 nm and 188 nm in diameter, respectively, were produced.

Results:

An encapsulation rate of up to 95% was observed. In vitro bioassays showed that the nanostructured cyclotides were partially able to control the development of the colorectal adenocarcinoma cell line CACO2 and the breast cancer cell line MCF-7.

Conclusion:

Data reported herein indicate that nanoformulated cyclotides exhibit antitumor activity and sustained drug release. Thus, the system using Eudragit® nanocapsules seems to be efficient for cyclotide encapsulation and probably could be used to target specific tumors in future studies.

Galactosylated chitosan-functionalized mesoporous silica nanoparticles for efficient colon cancer cell-targeted drug delivery

Targeted drug delivery to colon cancer cells can significantly enhance the therapeutic efficiency. Herein, we developed 5-fluorouracil (5-FU)-loaded amino-functionalized mesoporous silica nanoparticle (MSN-NH2)-based galactosylated chitosans (GCs), which are galactose receptor-mediated materials for colon-specific drug delivery systems. Both unmodified and functionalized nanoparticles were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, nitrogen sorption and dynamic light scattering. Drug loading capacity and drug release properties were determined by ultraviolet spectrophotometry. 5-FU@MSN-NH2/GC showed high loading capacity and possessed much higher cytotoxicity on human colon cancer cells (SW620 cells) than 5-FU@MSN-NH2 and free 5-FU. But, MSN-NH2/GC did not show significant cytotoxicity. Subsequently, 5-FU@MSN-NH2/GC anti-cancer activity on SW620 cells in vitro was confirmed by cell apoptosis. These results are consistent with the cellular uptake test in which MSN-NH2/GC could specifically recognize and bind to cancer cells by the galectin-receptor recognition. But, it is found that pre-addition of galactose in the medium, leading to competitive binding to the galectin receptor of SW620 cells, resulted in a decrease in the binding of MSN-NH2/GC to the galectin receptor. The results demonstrated the inorganic-organic nanocomposite could be used as a promising drug delivery carrier for the targeted delivery of drug into galectin-positive colon cancer cells to improve therapeutic index while reducing side effects.

Galactosylated Chitosan-Functionalized Mesoporous Silica Nanoparticle Loading by Calcium Leucovorin for Colon Cancer Cell-Targeted Drug Delivery

Targeted drug delivery to colon cancer cells can significantly improve the efficiency of treatment. We firstly synthesized carboxyl-modified mesoporous silica nanoparticles (MSN⁻COOH) via two-step synthesis, and then developed calcium leucovorin (LV)-loaded carboxyl-modified mesoporous silica nanoparticles based on galactosylated chitosan (GC), which are galectin receptor-mediated materials for colon-specific drug delivery systems. Both unmodified and functionalized nanoparticles were characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR), nitrogen sorption, and dynamic light scattering (DLS). Drug release properties and drug loading capacity were determined by ultraviolet spectrophotometry (UV). LV@MSN⁻COOH/GC had a high LV loading and a drug loading of 18.07%. In vitro, its release, mainly by diffusion, was sustained release. Cell experiments showed that in SW620 cells with the galectin receptor, the LV@MSN⁻COOH/GC metabolized into methyl tetrahydrofolic acid (MTHF) and 5-fluorouracil (5-FU)@MSN⁻NH₂/GC metabolized into FdUMP in vivo. MTHF and 5-fluoro-2'-deoxyuridine 5'-monophosphate (FdUMP) had combined inhibition and significantly downregulated the expression of thymidylate synthase (TS). Fluorescence microscopy and flow cytometry experiments show that MSN⁻COOH/GC has tumor cell targeting, which specifically recognizes and binds to the galectin receptor in tumor cells. The results show that the nano-dosing system based on GC can increase the concentrations of LV and 5-FU tumor cells and enhance their combined effect against colon cancer.

Stereoselective Double Reduction of 3-Methyl-2-cyclohexenone, by Use of Palladium and Platinum Nanoparticles, in Tandem with Alcohol Dehydrogenase

The combination of metal nanoparticles (Pd or Pt NPs) with NAD-dependent thermostable alcohol dehydrogenase (TADH) resulted in the one-flask catalytic double reduction of 3-methyl-2-cyclohexenone to 3-(1S,3S)-methylcyclohexanol. In this article, some assumptions about the interactions between a chemocatalyst and a biocatalyst have been proposed. It was demonstrated that the size of the NPs was the critical parameter for the mutual inhibition: the bigger the NPs, the more harmful for the enzyme they were, even if the NPs themselves were only moderately inactivated. Conversely, the smaller the NPs, the more minimal the TADH denaturation, although they were dramatically inhibited. Resuming, the chemocatalysts were very sensitive to deactivation, which was not related to the amount of enzyme used, while the inhibition of the biocatalyst can be strongly reduced by minimizing the NPs/TADH ratio used to catalyze the reaction. Among some methods to avoid direct binding of NPs with TADH, we found that using large Pd NPs and protecting their surfaces with a silica shell, the overall yield of 3-(1S,3S)-methylcyclohexanol was maximized (36%).

Mesoporous Silica Nanoparticles

Integration of nanotechnology and biomedicine has offered great opportunities for the development of nanoscaled therapeutic platforms. Amongst various nanocarriers, mesoporous silica nanoparticles (MSNs) is one of the most developed and promising inorganic materials-based drug delivery system for clinical translations due to their simple composition and nanoporous structure. MSNs possess unique structural features, for example, well-defined morphology, large surface areas, uniform size, controllable structure, flexible pore volume, tunable pore sizes, extraordinarily high loading efficiency, and excellent biocompatibility. Progress in structure control and functionalization may endow MSNs with functionalities that enable medical applications of these integrated nanoparticles such as molecularly targeted drug delivery, multicomponent synergistic therapy, in vivo imaging and therapeutic capability, on-demand/stimuli-responsive drug release, etc. In this chapter, the authors overview MSNs' characteristics and the scientific efforts developed till date involving drug delivery and biomedical applications.

Application of a lipid-coated hollow calcium phosphate nanoparticle in synergistic co-delivery of doxorubicin and paclitaxel for the treatment of human lung cancer A549 cells

In this study, we developed a lipid-coated hollow calcium phosphate (LCP) nanoparticle for the combined application of two chemotherapeutic drugs to human lung cancer A549 cells. Hydrophilic doxorubicin (DOX) was incorporated into the hollow structure of hollow calcium phosphate (HCP), and a lipid bilayer containing hydrophobic paclitaxel (PTX) was subsequently coated on the surface of HCP. The study on combinational effects demonstrated that the combination of DOX and PTX at a mass ratio of 12:1 showed a synergistic effect against A549 cells. The particle size, zeta potential, and encapsulation efficiency were measured to obtain optimal values: particle size was 335.0 3.2 nm, zeta potential −41.1 mV, and encapsulation efficiency 80.40%±2.24%. An in vitro release study indicated that LCP produced a sustained drug release. A549 cells had a better uptake of LCP with good biocompatibility. Furthermore, in vitro cytotoxicity experiment, apoptosis analysis, in vivo anti-tumor efficacy and protein expression analysis of Bax, Bcl-2, and Caspase-3 demonstrated that the co-delivery system based on LCP had significant synergistic anti-tumor activity. All conclusions suggested that LCP is a promising platform for co-delivery of multiple anti-tumor drugs.

Targeted delivery and pH-responsive release of doxorubicin to cancer cells using calcium carbonate/hyaluronate/glutamate mesoporous hollow spheres

Currently, the efficacies of the existing anticancer drugs used in chemotherapy are still unsatisfactory. Therefore, drug delivery system has received considerable research interest. In the present study, calcium carbonate/hyaluronate/glutamate mesoporous hollow spheres are prepared through a facile method. The results indicate that the mesoporous hollow spheres can efficiently load the anticancer drug doxorubicin. Through the specific binding of hyaluronate on hollow spheres with CD44 receptors overexpressed on cancer cells, the drug-loaded hollow spheres can be specifically delivered to target cancer cells. Owing to the gradually dissolution of calcium carbonate in the weak acidic microenvironment of cancer cells, the loaded doxorubicin can be released over the period of 14days with pH-responsive and sustained manner to specifically and significantly treat cancers. Through loaded onto the hollow spheres, the IC₅₀ value of doxorubicin for HeLa cancer cells is 0.0113μg/mL, much lower than that of the free doxorubicin (0.0801μg/mL). However, the IC₅₀ value of doxorubicin for V79-4 cells is 0.2032μg/mL, obviously higher than that of the free DOX (0.1396μg/mL). The specificity of the doxorubicin between normal and cancer cells can be enhanced about 10-fold. The current study suggests the possible application of pH-responsive inorganic carriers for efficiently treatment of human cancers.

Intracellular pH-responsive and rituximab-conjugated mesoporous silica nanoparticles for targeted drug delivery to lymphoma B cells

Background

One of the main problems in B cell lymphoma treatment is severe adverse effects and low therapeutic efficacy resulting from systemic chemotherapy. A pH-sensitive controlled drug release system based on mesoporous silica nanoparticles was constructed for targeted drug delivery to tumor cells to reduce systemic toxicity and improve the therapeutic efficacy.

Methods

In this study, the doxorubicin (DOX) was filled into the mesopores of the functional MSNs (DMSNs). Furthermore, rituximab was introduced as the targeted motif of functional DMSNs using an avidin-biotin bridging method to evaluate the targetability to tumor cells. Then, the cell viability and apoptosis efficiency after treatment with rituximab-conjugated DMSNs (RDMSNs) were estimated by using CCK-8 assay and flow cytometry, respectively. Additionally, the research in vivo was performed to evaluate the enhanced antitumor efficacy and the minimal toxic side effects of RDMSNs. Also, TUNEL staining assay was employed to explore the mechanism of antitumor effects of RDMSNs.

Results

This targeted drug delivery system exhibited low premature drug release at a physiological pH and efficient pH-responsive intracellular release under weakly acidic conditions. The in vitro tests confirmed that targeted RDMSNs could selectively adhere to the surface of lymphoma B cells via specific binding with the CD20 antigen and be internalized into CD20 positive Raji cells but few CD20 negative Jurkat cells, which leads to increased cytotoxicity and apoptosis of the DOX in Raji cells due to the release of the entrapped DOX with high efficiency in the slightly acidic intracellular microenvironment. Furthermore, the in vivo investigations confirmed that RDMSNs could efficiently deliver DOX to lymphoma B cells by pH stimuli, thus inducing cell apoptosis and inhibiting tumor growth, while with minimal toxic side effects.

Conclusions

This targeted and pH-sensitive controlled drug delivery system has the potential for promising application to enhance the therapeutic index and reduce the side effects of B cell lymphoma therapy.

Facile synthesis of monodisperse of hollow mesoporous SiO2 nanoparticles and in-situ growth of Ag nanoparticles for antibacterial

Monodispersed hollow mesoporous silica nanoparticles (HMSNs) are successfully synthesized via a facile dual template method, in which poly(styrene-co-methyl methacrylate-co-methacrylic acid) (PS-PMMA-PMAA) particles are used as hard template for producing the hollow structure and cetyltrimethylammonium bromide (CTAB) used for introducing the mesopores in the silica shells. The obtained HMSNs possess uniform diameter and morphology, and the shell of which could be adjusted by changing the addition of silicon precursor. The synthesized HMSNs have been characterized by transmission electron microscopy (TEM) and nitrogen physisorption. Furthermore, the HMSNs are used as support for in-situ deposition of silver nanoparticles (Ag NPs) using n-butylamine as reducing agent for AgNO3 in ethanol. Significantly, Ag NPs were successfully supported in the HMSNs without any aggregation. The Ag-deposited HMSNs showed excellent dispersibility in ethanol and water, and their antibacterial activity against Escherichia coli (E. coli) ATCC 25922 and Staphylococcus aureus (S. aureus) ATCC 6538 have been demonstrated. Therefore, the unique nanostructure based on the HMSNs provided a useful platform for the fabrication of antibacterial agent with superior activity and accessibility. And also, it is expected to be a significant template for the synthesis of other novel nanostructures.

Monodispersed hollow polymer/iron eutectic nanospheres

Monodispersed hollow polymer/iron eutectic nanoparticles with the size range of 18–30 nm were prepared by a simple method. These particles can be applied in chemical catalysis and nanoreactors.

One-pot controllable synthesis of carboxylic group functionalized hollow mesoporous silica nanospheres for efficient cisplatin delivery

A simple one-pot synthesis and functionalization of HMSNs with COOH as a sustained and controlled release drug delivery system.

Theranostic hollow/mesoporous organosilica nanospheres enhance the therapeutic efficacy of anticancer drugs in metastatic hormone-resistant prostate cancer

Hollow mesoporous silica materials have received intensive interest in the field of cancer treatment owing to their large drug loading capacity, controlled release property and excellent biocompatibility.

Overcoming acquired drug resistance in colorectal cancer cells by targeted delivery of 5-FU with EGF grafted hollow mesoporous silica nanoparticles

Acquired drug resistance (ADR) can be developed in colorectal cancer cells after 5-fluorouracil (5-FU) treatment and diminish the effectiveness of chemotherapy. In this work, acquired 5-FU resistance in the colorectal cancer cell line SW480 was obtained with the up-regulation of dihydropyrimidine dehydrogenase (DPYD) gene expression which can convert 5-FU to its inactive metabolite. To overcome ADR in colorectal cancer, hollow mesoporous silica nanoparticles (HMSNs) grafted with epidermal growth factor (EGF) were used as nanocarriers to deliver 5-FU to colorectal cancer cells with acquired drug resistance. The effect and mechanism of 5-FU loaded EGF grafted HMSNs (EGF-HMSNs-5-FU) in overcoming acquired drug resistance in SW480/ADR cells were studied. The EGF-HMSNs were demonstrated to be specifically internalized in EGFR overexpressed SW480/ADR cells via a receptor-mediated endocytosis and can escape from endo-lysosomes. The EGF-HMSNs-5-FU exhibited much higher cytotoxicity on SW480/ADR cells than HMSNs-5-FU and free 5-FU while the plain HMSNs did not show significant cytotoxicity. The mechanism of EGF-HMSNs-5-FU in overcoming drug resistance in SW480/ADR cells could be attributed to the specific internalization of EGF-HMSNs-5-FU in EGFR overexpressed cells which can lead to high intracellular drug accumulation and cause cell death through S phase arrest.

The control of epidermal growth factor grafted on mesoporous silica nanoparticles for targeted delivery

The performance of biomaterials in a biological environment is largely influenced by the surface properties of the biomaterials. In particular, grafted targeting ligands significantly impact the subsequent cellular interactions. The utilisation of a grafted epidermal growth factor (EGF) is effective for targeted delivery of drugs to tumours, but the amount of these biological attachments cannot be easily quantified as most characterization methods could not detect the extremely low amount of EGF ligands grafted on the surface of nanoparticles. In this study, hollow mesoporous silica nanoparticles (HMSNs) were functionalized with amine groups to conjugate with EGFs via carbodiimide chemistry. Time of flight secondary ion mass spectrometry (ToF-SIMS), a very surface specific technique (penetration depth <1.5 nm), was employed to study the binding efficiency of the EGF to the nanoparticles. Principal component analysis (PCA) was implemented to track the relative surface concentrations of EGFs on HMSNs. It was found that ToF-SIMS combined with the PCA technique is an effective method to evaluate the immobilization efficiency of EGFs. Based on this useful technique, the quantity and density of the EGF attachments that grafted on nanoparticles can be effectively controlled by varying the EGF concentration at grafting stages. Cell experiments demonstrated that the targeting performance of EGFR positive cells was affected by the number of EGFs attached on HMSNs.

Preparation and catalytic applications of nanomaterials: a review

The present review systematically summarizes the synthesis and specific catalytic applications of nanomaterials such as MSN, nanoparticles, LD hydroxides, nanobubbles, quantum dots,etc.