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Nanoparticle-based targeting of overexpressed cell-surface receptors is a promising strategy that provides precise delivery of drugs to cancer cells. In the present study, we developed highly reproducible and monodispersed, chitosan-coated (pH-responsive), doxorubicin-loaded, aptamer-mesoporous silica nanoparticle (MSN) bioconjugates for actively targeting breast cancer cells harboring overexpression of EGF receptors (EGFR/HER2). The developed targeted MSNs demonstrated higher uptake and cytotoxicity of triple negative and HER2 positive breast cancer cells when compared to non-targeted MSNs. The chitosan coating imparted pH-responsiveness and endo/lysosomal escape ability to MSNs, which augmented cytosolic delivery of an anticancer drug. Partial carboxylation of chitosan coated on MSNs allowed for a greater release of drug in a shorter duration of time while retaining pH-responsiveness and endo/lysosomal escape ability. Overall, the coating of carboxylated-chitosan over MSNs enabled tunable drug release kinetics, conjugation of aptamers (targeting agents), and endo/lysosomal escape which together significantly enhanced the efficacy of the developed drug delivery system., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The collection of different bulk materials forms the nanoparticles, where the properties of the nanoparticle are solely different from the individual components before being ensembled. Selfassembled nanoparticles are basically a group of complex functional units that are formed by gathering the individual bulk components of the system. It includes micelles, polymeric nanoparticle, carbon nanotubes, liposomes and niosomes, etc . This self-assembly has progressively heightened interest to control the final complex structure of the nanoparticle and its associated properties. The main challenge of formulating self-assembled nanoparticle is to improve the delivery system, bioavailability, enhance circulation time, confer molecular targeting, controlled release, protection of the incorporated drug from external environment and also serve as nanocarriers for macromolecules. Ultimately, these self-assembled nanoparticles facilitate to overcome the physiological barriers in vivo . Self-assembly is an equilibrium process where both individual and assembled components are subsisting in equilibrium. It is a bottom up approach in which molecules are assembled spontaneously, non-covalently into a stable and welldefined structure. There are different approaches that have been adopted in fabrication of self-assembled nanoparticles by the researchers. The current review is enriched with strategies for nanoparticle selfassembly, associated properties, and its application in therapy., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Purpose: As well as functioning as a ligand that is selectively internalized by cells overexpressing human epidermal growth factor receptor-2 (HER2), HApt can exert cytotoxic effects by inducing cross-linking and subsequent translocation of HER2 to cytoplasmic vesicles, such downregulation of HER2 inhibits cell proliferation and induces apoptosis. We aimed to exploit the potential of HApt as both a targeting agent and antagonist to maximize the efficacy of mesoporous silica nanoparticle (MSN)-based drug release systems for HER2-positive breast cancer. Materials and methods: We fabricated novel HApt aptamer-functionalized pH-sensitive β-cyclodextrin (β-CD)-capped doxorubicin (DOX)-loaded mesoporous silica nanoparticles (termed MSN-BM/CD-HApt@DOX) for targeted delivery and selective targeting of HER2-positive cells. MSN-functionalized benzimidazole (MSN-BM) was used to load and achieve pH stimuli-responsive release of the chemotherapeutic agent doxorubicin (DOX). β-cyclodextrin was introduced as a gatekeeper for encapsulated DOX and HApt as a selective HER2-targeting moiety and biotherapeutic agent. Results: Physical and chemical characterizations (FT-IR, XRD, TEM and BET) confirmed successful construction of MSN-BM/CD-HApt@DOX nanoparticles. In vitro release assays verified pH-sensitive DOX release. MSN-BM/CD-HApt@DOX (relative DOX concentration, 3.6 μg/mL) underwent HER2-mediated endocytosis and was more cytotoxic to HER2-positive SKBR3 cells than HER2-negative MCF7 cells. MSN-BM/CD-HApt@DOX also exhibited better uptake and stronger growth inhibition in SKBR3 cells than the control MSN-BM/CD-NCApt@DOX functionalized with a scrambled nucleotide sequence on CD. Overall, intracellular delivery of DOX and the biotherapeutic agent HApt resulted in synergistic cytotoxic effects in HER2-positive cancer cells in comparison to either DOX or HApt alone. Conclusion: MSN-BM/CD-HApt@DOX enables HER2-mediated targeting and biotherapeutic effects as well as pH-responsive DOX drug release, resulting in synergistic cytotoxic effects in HER2-overexpressing cells in vitro. This novel nanocarrier could potentially enable specific targeting to improve the efficacy of chemotherapy for HER2-positive cancer., Competing Interests: The authors report no conflicts of interest in this work.

Nanoparticular drug delivery system (NDDS) has great potential for enhancing the efficacy of traditional chemotherapeutic drugs. However, it is still a great challenge to fabricate a biocompatible NDDS with simple structure capable of optimizing therapeutic efficacy, such as high tumor accumulation, suitable drug release profile (e.g. no premature drug leakage in normal physiological conditions while having a rapid release in cancer cells), low immunogenicity, as well as good biocompatibility. In this work, a simple core/shell structured nanoparticle was fabricated for prostate cancer treatment, in which a mesoporous silica nanoparticle core was applied as a container to high-efficiently encapsulate drugs (doxorubicin, DOX), CaCO 3 interlayer was designed to act as sheddable pH-sensitive gatekeepers for controlling drug release, and cancer cell membrane wrapped outlayer could improve the colloid stability and tumor accumulation capacity. In vitro cell experiments demonstrated that the as-prepared nanovehicles (denoted as DOX/MSN@CaCO 3 @CM) could be efficiently uptaken by LNCaP-AI prostate cancer cells and even exhibited a better anti-tumor efficiency than free DOX. In addition, Live/Dead cell detection and apoptosis experiment demonstrated that MSN/DOX@CaCO 3 @CM could effectively induce apoptosis-related death in prostate cancer cells. In vivo antitumor results demonstrated that DOX/MSN@CaCO 3 @CM administration could remarkably suppress the tumor growth. Compared with other tedious approaches to optimize the therapeutic efficacy, this study provides an effective drug targeting system only using naturally biomaterials for the treatment of prostate cancer, which might have great potential in clinic usage., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Purpose: Antiangiogenic drugs usually have short-acting efficacy and poor treatment compliance. The purpose of this study was to determine whether mesoporous silica nanoparticles (MSNs) could be utilized as a nanodrug delivery system for improving antiangiogenic therapy., Materials and Methods: MSN-encapsulated bevacizumab nanoparticles were prepared by the nanocasting strategy and characterized by Fourier transform infrared, transmission electron microscopy, and Brunauer-Emmett-Teller method. Encapsulation efficiency and drug loading efficiency of MSN-encapsulated bevacizumab nanoparticles were calculated. The pharmacokinetics, cytotoxicity, and tissue toxicity were evaluated in vitro and in vivo. The antiangiogenic effects of MSN-bevacizumab nanoparticles were evaluated in vitro and in vivo., Results: MSN encapsulation could prolong the residency of bevacizumab in vitreous/aqueous humor and maintain the long-lasting drug concentration. MSN-encapsulated bevacizumab nanoparticles did not show any obvious cytotoxicity and tissue toxicity. MSN-encapsulated bevacizumab nanoparticles were more effective than bevacizumab in suppressing vascular endothelial growth factor-induced endothelial cell proliferation, migration, and tube formation in vitro. MSN-encapsulated bevacizumab nanoparticles showed sustained inhibitory effects on corneal neovascularization and retinal neovascularization in vivo., Conclusion: This study provides a novel strategy of encapsulating bevacizumab to protect and deliver it, which could increase the time between administration and formulation shelf-life. MSN-encapsulated bevacizumab is a promising drug delivery alternative of antiangiogenic therapy., Competing Interests: Disclosure The authors report no conflicts of interest in this work.

Here, a positive feedback strategy was utilized to amplify the concentration of intracellular reactive oxygen species (ROS) and a ROS-triggered self-accelerating drug release nanosystem (defined as T/D@RSMSNs) was demonstrated for enhanced tumor chemotherapy. The mesoporous silica nanoparticles (MSNs) based nanocarriers were gated by β-cyclodextrin (β-CD) through the ROS-cleavable thioketal (TK) linker to encapsulate the anticancer drug doxorubicin hydrochloride (DOX) and ROS producing agent α-tocopheryl succinate (α-TOS), whose surface was further anchored with adamantane conjugated poly(ethylene glycol) chain (AD-PEG) via host-guest interaction. It was found that in human breast cancer (MCF-7) cells, T/D@RSMSNs could not only release DOX and α-TOS initiatively, but also lead to increased concentration of intracellular ROS, which could be used as new trigger to cut away TK linkage and then in turn facilitate the further release of DOX for enhanced chemotherapy. Both in vitro and in vivo experiments demonstrated that T/D@RSMSNs exhibited more significant antitumor activity in the human breast cancer than the traditional single-DOX loaded ROS-responsive nanocarrier. This novel ROS-triggered self-accelerating drug release nanosystem with remarkably improved therapeutic effects could provide a general strategy to branch out the applications of existing ROS-responsive drug delivery systems (DDSs)., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

With the development of nanotechnology, the application of nanomaterials in the field of drug delivery has attracted much attention in the past decades. Mesoporous silica nanoparticles as promising drug nanocarriers have become a new area of interest in recent years due to their unique properties and capabilities to efficiently entrap cargo molecules. This review describes the latest advances on the application of mesoporous silica nanoparticles in drug delivery. In particular, we focus on the stimuli-responsive controlled release systems that are able to respond to intracellular environmental changes, such as pH, ATP, GSH, enzyme, glucose, and H 2 O 2 . Moreover, drug delivery induced by exogenous stimuli including temperature, light, magnetic field, ultrasound, and electricity is also summarized. These advanced technologies demonstrate current challenges, and provide a bright future for precision diagnosis and treatment., Competing Interests: The authors report no conflicts of interest in this work.

Many nanocarrier cancer therapeutics currently under development, as well as those used in the clinical setting, rely upon the enhanced permeability and retention (EPR) effect to passively accumulate in the tumor microenvironment and kill cancer cells. In leukemia, where leukemogenic stem cells and their progeny circulate within the peripheral blood or bone marrow, the EPR effect may not be operative. Thus, for leukemia therapeutics, it is essential to target and bind individual circulating cells. Here, we investigate mesoporous silica nanoparticle (MSN)-supported lipid bilayers (protocells), an emerging class of nanocarriers, and establish the synthesis conditions and lipid bilayer composition needed to achieve highly monodisperse protocells that remain stable in complex media as assessed in vitro by dynamic light scattering and cryo-electron microscopy and ex ovo by direct imaging within a chick chorioallantoic membrane (CAM) model. We show that for vesicle fusion conditions where the lipid surface area exceeds the external surface area of the MSN and the ionic strength exceeds 20 mM, we form monosized protocells (polydispersity index <0.1) on MSN cores with varying size, shape, and pore size, whose conformal zwitterionic supported lipid bilayer confers excellent stability as judged by circulation in the CAM and minimal opsonization in vivo in a mouse model. Having established protocell formulations that are stable colloids, we further modified them with anti-EGFR antibodies as targeting agents and reverified their monodispersity and stability. Then, using intravital imaging in the CAM, we directly observed in real time the progression of selective targeting of individual leukemia cells (using the established REH leukemia cell line transduced with EGFR) and delivery of a model cargo. Overall, we have established the effectiveness of the protocell platform for individual cell targeting and delivery needed for leukemia and other disseminated disease.

Unlabelled: Small-molecule drug combination therapies are an attractive approach to enhancing cancer chemotherapeutic responses. Therefore, this study aimed to investigate the potential of axitinib (AXT) and celastrol (CST) in targeting angiogenesis and mitochondrial-based apoptosis in cancer. Therefore, we prepared AXT/CST-loaded combination nanoparticles (ACML) with CST loaded in the mesoporous silica nanoparticles (MSN) and AXT in PEGylated lipidic bilayers. We showed that ACML effectively inhibited angiogenesis and mitochondrial function and was efficiently internalized in SCC-7, BT-474, and SH-SY5Y cells. Furthermore, hypoxia-inducible factor (HIF)-1α expression, which increased under hypoxic conditions in all cell lines exposed to ACML, markedly decreased, which may be critical for tumor inhibition. Western blotting showed the superior anticancer effect of combination nanoparticles in different cancer cells. Compared to the cocktail (AXT/CST), ACML induced synergistic cancer cell apoptosis. The AXT/CST-based combination nanoparticle synergism might be mediated by AXT, which controls vascular endothelial growth factor receptors while CST acts on target cell mitochondria. Importantly, ACML-treated mice showed remarkably higher tumor inhibition (64%) than other groups did in tumor xenograft models. Tumor xenograft immunohistochemistry revealed elevated caspase-3 and poly (ADP-ribose) polymerase and reduced CD31 and Ki-67 expression, clearly suggesting tumor apoptosis through mitochondrial and antiangiogenic effects. Overall, our results indicate that ACML potentially inhibited cell proliferation and induced apoptosis by blocking mitochondrial function, leading to enhanced antitumor efficacy., Statement of Significance: In this research, we formulated an anticancer drug combination nanoparticle loaded with axitinib (AXT) in the lipidic bilayer of PEGylated liposomes and celastrol (CST) in mesoporous silica nanoparticles. The anticancer effects of the AXT/CST-loaded combination nanoparticle (ACML) were synergistic and superior to the other formulations and involved more efficient drug delivery to the tumor site with enhanced effects on angiogenesis and mitochondrial function. Therefore, our study demonstrated that the inhibition of cell proliferation and induction of apoptosis by ACML, which was mediated by blockade of mitochondrial function and anti-angiogenesis, led to enhanced antitumor efficacy, which may be potentially useful in the clinical treatment of cancer., (Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

Effective and rapid treatment of tularemia is needed to reduce morbidity and mortality of this potentially fatal infectious disease. The etiologic agent, Francisella tularensis, is a facultative intracellular bacterial pathogen which infects and multiplies to high numbers in macrophages. Nanotherapeutics are particularly promising for treatment of infectious diseases caused by intracellular pathogens, whose primary host cells are macrophages, because nanoparticles preferentially target and are avidly internalized by macrophages. A mesoporous silica nanoparticle (MSN) has been developed functionalized with disulfide snap-tops that has high drug loading and selectively releases drug intracellularly in response to the redox potential. These nanoparticles, when loaded with Hoechst fluorescent dye, release their cargo exclusively intracellularly and stain the nuclei of macrophages. The MSNs loaded with moxifloxacin kill F. tularensis in macrophages in a dose-dependent fashion. In a mouse model of lethal pneumonic tularemia, MSNs loaded with moxifloxacin prevent weight loss, illness, and death, markedly reduce the burden of F. tularensis in the lung, liver, and spleen, and are significantly more efficacious than an equivalent amount of free drug. An important proof-of-principle for the potential therapeutic use of a novel nanoparticle drug delivery platform for the treatment of infectious diseases is provided., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We have optimized mesoporous silica nanoparticles (MSNs) functionalized with pH-sensitive nanovalves for the delivery of the broad spectrum fluoroquinolone moxifloxacin (MXF) and demonstrated its efficacy in treating Francisella tularensis infections both in vitro and in vivo. We compared two different nanovalve systems, positive and negative charge modifications of the mesopores, and different loading conditions-varying pH, cargo concentration, and duration of loading-and identified conditions that maximize both the uptake and release capacity of MXF by MSNs. We have demonstrated in macrophage cell culture that the MSN-MXF delivery platform is highly effective in killing F. tularensis in infected macrophages, and in a mouse model of lethal pneumonic tularemia, we have shown that the drug-loaded MSNs are much more effective in killing F. tularensis than an equivalent amount of free MXF.

Traditional chelator-based radio-labeled nanoparticles and positron emission tomography (PET) imaging are playing vital roles in the field of nano-oncology. However, their long-term in vivo integrity and potential mismatch of the biodistribution patterns between nanoparticles and radio-isotopes are two major concerns for this approach. Here, we present a chelator-free zirconium-89 ((89)Zr, t1/2 = 78.4 h) labeling of mesoporous silica nanoparticle (MSN) with significantly enhanced in vivo long-term (>20 days) stability. Successful radio-labeling and in vivo stability are demonstrated to be highly dependent on both the concentration and location of deprotonated silanol groups (-Si-O(-)) from two types of silica nanoparticles investigated. This work reports (89)Zr-labeled MSN with a detailed labeling mechanism investigation and long-term stability study. With its attractive radio-stability and the simplicity of chelator-free radio-labeling, (89)Zr-MSN offers a novel, simple, and accurate way for studying the in vivo long-term fate and PET image-guided drug delivery of MSN in the near future.

Targeting nanocontainers to the pathological zone and controlling release of their cargoes, in particular delivery of anticancer drugs to specific tumor cells in a targeted and controlled manner, remain the key challenges in drug delivery. This paper reports the development of a traceable and tumor-targeted intracellular drug release nanocontainer. The nanocontainer is obtained by in situ growth of silver nanoparticles (AgNPs) on the surfaces of mesoporous silica nanospheres (MSNs) using a DNA-templated process. Additionally, drug release from the nanopores is achieved by selective glutathione (GSH)-triggered dismantle of the AgNPs, and the concurrent fluorescence change allows real-time monitoring of drug release efficacy and facile visualization of in vivo delivery events. After being functionalized with sgc8 aptamer on the outer shell of the AgNPs, the targeted nanocontainers are delivered into acute lymphoblastic leukemia cells by aptamer-mediated recognition and endocytosis. Moreover, the GSH-responsive process presents an improvement in the cell-specific drug release and chemotherapeutic inhibition of tumor growth.

The vascular endothelial growth factor (VEGF)/VEGF receptor (VEGFR) signaling cascade plays a critical role in tumor angiogenesis and metastasis and has been correlated with several poorly prognostic cancers such as malignant gliomas. Although a number of anti-VEGFR therapies have been conceived, inefficient drug administration still limits their therapeutic efficacy and raises concerns of potential side effects. In the present work, we propose the use of uniform mesoporous silica nanoparticles (MSNs) for VEGFR targeted positron emission tomography imaging and delivery of the anti-VEGFR drug (i.e., sunitinib) in human glioblastoma (U87MG) bearing murine models. MSNs were synthesized, characterized and modified with polyethylene glycol, anti-VEGFR ligand VEGF121 and radioisotope (64)Cu, followed by extensive in vitro, in vivo and ex vivo studies. Our results demonstrated that a significantly higher amount of sunitinib could be delivered to the U87MG tumor by targeting VEGFR when compared with the non-targeted counterparts. The as-developed VEGF121-conjugated MSN could become another attractive nanoplatform for the design of future theranostic nanomedicine.

Stimuli-responsive drug delivery systems are highly desirable for improved therapeutic efficacy and minimized adverse effects of drugs. Mesoporous silica nanoparticles (MSNs) functionalized with pentadentate ligands, N-(3-trimethoxysilylpropyl)ethylenediamine triacetate (TSP-DATA), in the presence of metal ions with and without myoglobin (Mb)-containing surface-accessible histidine residues, were constructed for pH-triggered controlled release. The DATA ligands immobilized on the MSN pore outlets could encapsulate cargo within the pores by metal latching across pore openings, and release efficiency increased with the increase of surface density of the DATA ligands. The release efficiencies for the metal-chelating protein nanogates, through multiple-site binding of Mb with the metal-chelating ligands, were higher than those for the metal-latching ligand nanogates but were almost independent of surface density of the ligands investigated. Both the metal-latching ligands and the metal-chelating proteins played a synergetic role in gating MSNs for high-loading drug delivery and stimuli-responsive controlled release. The constructed Mb-Cu(2+)-gated MSN delivery system has promising applications in targeted drug therapy of tumors.

This study reports the synthesis of mesoporous silica nanoparticle-encapsulated alginate microparticles (MSN@Alg) for sustained release and targeting therapy. The MSN@Alg was synthesized by air dynamical atomization, and the effects of several critical factors including concentration of alginate solution, flow rate of alginate solution, flow rate of air, the distance between nozzle and calcium bath, and stirring rate of calcium on the particle size of the synthesized MSN@Alg were investigated. For studying the sustained release properties of the MSN@Alg, rhodamine 6G (R6G) was used as a model drug, and we compared the release properties of R6G/MSN and R6G/MSN@Alg using different concentrations of alginate, concentrations and volumes of phosphate-buffered saline (PBS) buffer solutions. The sustained release behavior of the R6G/MSN@Alg system can be prolonged to 20 days with an optimal condition of 1 mg R6G/MSN@Alg to 2 mL PBS (10 mM). To achieve targeting therapy, an anticancer drug, doxorubicin (Dox), was loaded into MSN@Alg, and a arginine, glycine, and aspartic acid (RGD)-based peptide was functionalized onto the surface of MSN@Alg for the purpose of specific targeting. The results showed that the intracellular drug delivery efficiency was greatly enhanced (i.e., 3.5-folds) for the Dox/MSN@Alg-RGD drug delivery system., (Copyright © 2013 Wiley Periodicals, Inc.)

Mesoporous silica nanoparticles (MSNs) are physically and chemically stable inorganic nanomaterials that have been attracting much attention as carriers for drug delivery systems in the field of nanomedicine. In the present study, we investigated the potential of MSN vaccines that incorporate antigen peptides for use in cancer immunotherapy. In vitro experiments demonstrated that fluorescently labeled MSNs accumulated in a line of mouse dendritic cells (DC2.4 cells), where the particles localized to the cytosol. These observations could suggest that MSNs have potential for use in delivering the loaded molecules into antigen-presenting cells, thereby stimulating the host acquired immune system. In vivo experiments demonstrated prolonged survival in mice implanted with ovalbumin (OVA)-expressing lymphoma cells (E.G7-OVA cells) following subcutaneous inoculation with MSNs incorporating OVA antigen peptides. Furthermore, OVA-specific immunoglobulin G antibodies and cytotoxic T lymphocytes were detected in the serum and the spleen cells, respectively, of mice inoculated with an MSN-OVA vaccine, indicating the induction of antigen-specific responses in both the humoral and cellular immune systems. These results suggested that the MSN therapies incorporating antigen peptides may serve as novel vaccines for cancer immunotherapy. [ABSTRACT FROM AUTHOR]

Liver cancer, especially hepatocellular carcinoma, is an important cause of cancer-related death, and its incidence is increasing worldwide. Nano drug delivery systems have shown great promise in the treatment of cancers. In order to improve their therapeutic efficacy, it is very important to realize the high accumulation and effective release of drugs at the tumor site. In this manuscript, using doxorubicin (DOX) as a model drug, CD13-targeted mesoporous silica nanoparticles coated with NGR-peptide-modified pegylated carboxymethyl chitosan were constructed (DOX/MSN-CPN). DOX/MSN-CPN comprises a spherical shape with an obvious capping structure and a particle size of 125.01 ± 1.52 nm. With a decrease in pH, DOX/MSN-CPN showed responsive desorption from DOX/MSN-CPN and pH-responsive release of DOX was observed. Meanwhile, DOX/MSN-CPN could be efficiently absorbed through NGR-mediated internalization in vitro and could efficiently deliver DOX to tumor tissues with long accumulation times in vivo, suggesting good active targeting properties. Moreover, significant tumor inhibition has been observed in antitumor studies in vivo. This study provides a strategy of utilizing DOX/MSN-CPN as a nano-platform for drug delivery, which has superb therapeutic efficacy and safety for the treatment of hepatocellular carcinoma both in vivo and in vitro. [ABSTRACT FROM AUTHOR]

[Display omitted] Controlling the drug release and restricting its presence in healthy organs is extremely valuable. In this study, mesoporous silica nanoparticles (MSN) as the core, loaded with paclitaxel (PTX), were coated with a non-porous silica shell functionalized with disulfide bonds. The nanoparticles were further coated with polyethylene glycol (PEG) via disulfide linkages. We analyzed the physicochemical properties of nanoparticles, including hydrodynamic size via Dynamic Light Scattering (DLS), zeta potential, X-ray Diffraction (XRD) patterns, Fourier-Transform Infrared (FTIR) spectra, and imaging through Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM). The drug release profile in two distinct glutathione (GSH) concentrations of 2 µM and 10 µM was measured. The cellular uptake of nanoparticles by MCF-7 cell line was determined using Confocal Laser Scanning Microscopy (CLSM) images and flow cytometry. Furthermore, the cell viability and the capability of nanoparticles to induce apoptosis in MCF-7 cell line were studied using the MTT assay and flow cytometry, respectively. Our investigations revealed that the release of PTX from the drug delivery system was redox-responsive. Also, results indicated an elevated level of cellular uptake and efficient induction of apoptosis, underscoring the promising potential of this redox-responsive drug delivery system for breast cancer therapy. [ABSTRACT FROM AUTHOR]

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). 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. 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. 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. [Display omitted] • Elesclomol is an effective mitochondrion-targeting agent for treatment of wide variety of cancers. • Elesclomol can produce high levels of ROS within the organelle leading to cancer cell death. • Combination of Elesclomol with several therapeutic agents is also an alternative way to augment its anticancer potency. [ABSTRACT FROM AUTHOR]

Mesoporous silica nanoparticles (MSNs) have been well-researched in the design and fabrication of advanced drug delivery systems (DDSs) due to their advantages such as good biocompatibility, large specific surface area and pore volume for drug loading, easily surface modification, adjusted size and good thermal/chemical stability. For MSN-based DDSs, gate materials are also necessary. And natural polysaccharides, one kind of the most abundant natural resource, have been widely applied as the "gatekeepers" in MSN-based DDSs. Polysaccharides are cheap and rich in sources with good biocompatibility, and some of them have important biological functions. In this review article, polysaccharides including chitosan, hyaluronic acid, sodium alginate and dextran, et al. are briefly introduced. And the preparation processes and properties such as controlled drug release, cancer targeting and disease diagnosis of functional polysaccharide/MSN-based DDSs are discussed. [ABSTRACT FROM AUTHOR]

Low water solubility and thus low bioavailability limit the clinical application of fenbendazole (FBZ) as a potential anticancer drug. Solubilizing agents, such as Mobil Composition of Matter Number 41 (MCM) as a drug carrier, can improve the water solubility of drugs. In this study, PEGylated MCM (PEG-MCM) nanoparticles (NPs) were synthesized and loaded with FBZ (PEG-MCM-FBZ) to improve its solubility and, as a result, its cytotoxicity effect against human prostate cancer PC-3 cells. The loading efficiency of FBZ onto PEG-MCM NPs was 17.2%. The size and zeta potential of PEG-MCM-FBZ NPs were 366.3 ± 6.9 nm and 24.7 ± 0.4 mV, respectively. They had a spherical shape and released the drug in a controlled manner at pH 1.2 and pH 6.2. PEG-MCM-FBZ were found to inhibit the migration of PC-3 cells, increase the cytotoxicity effects of FBZ against PC-3 cells by 3.8-fold, and were more potent by 1.4-fold, when compared to the non-PEGylated NPs. In addition, PEG-MCM-FBZ promoted the production of reactive oxygen species by 1.3- and 1.2-fold, respectively, when compared to FBZ and MCM-FBZ. Overall, the results demonstrate that PEG-MCM-FBZ NPs enhanced FBZ delivery to PC-3 cells; therefore, they have the potential to treat prostate cancer after a comprehensive in vivo study.

Mesoporous silica nanoparticles (MSNs) functionalized with redox‐sensitive or pH‐sensitive nanovalves for doxorubicin delivery and release by using recombinant human H chain ferritin (HFn) as a cap have been designed and fabricated. In both cases, transmission electron microscope observatory, dynamic light scattering change, Fourier transform infrared spectra examination, thermogravimetric analysis show that HFn can be chemically bonded to MSNs while retaining its ability to target transferrin receptor 1 (TfR1). Cargo loading and release studies demonstrate that HFn is an efficient capping agent, blocking the pores of MSN preventing cargo molecules from diffusing out, and is responsive to redox stimuli or pH changes. More importantly, HFn can not only cap the MSNs, but also enables targeted cargo delivery to malignant cells by binding to the TfR1 that has been overexpressed in various tumors, which can be reflected by the cell viability and fluorescence microscope analysis results comparing with cyclodextrin as the capping agent and TfR1 blocking assay. The in vivo study reveals the excellent efficacy of doxorubicin loaded and HFn capped MSNs on suppression of tumor growth. The new developed drug delivery system features mutually benefit and mutually support, providing strategy for achieving specific‐site therapeutics delivery systems. [ABSTRACT FROM AUTHOR]

In this paper, a targeting hyaluronic acid (HA)/mesoporous silica nanoparticle (MSN) based drug delivery system (DDS) with dual-responsiveness was prepared for cancer therapy. To avoid the side reaction between the anti-cancer drug doxorubicin hydrochloride (DOX) and HA, host-guest interaction was applied to fabricate the DDS named DOX@MSN-SS-N=C-HA. The "nanocontainer" MSN was modified with benzene ring via both pH-sensitive benzoic imine bond and redox-sensitive disulfide linkage. When DOX was loaded in the pores of MSN, the channels were then capped by the "gatekeeper" β -CD grafted HA (HA- g -CD) through host-guest interaction between β -CD and benzene. HA endowed the drug carriers with the targeting capability in CD44 over-expressed cancer cells. After cellular uptake, the carriers could rapidly release DOX for cell apoptosis due to both the hydrolysis of benzoic imine bond at low pH and the cleavage of disulfide bond at a high concentration of glutathione (GSH) intracellular. In vitro drug release studies and in vitro cytotoxicity studies were taken to investigate the dual-responsiveness of the carriers. And the CD44-receptor mediated cancer cell targeting capability was investigated as well. In conclusion, the targeted dual-responsive complex DDS fabricated through host-guest interaction has promising potential in cancer therapy. [ABSTRACT FROM AUTHOR]

Due to the difference of pH values between normal tissues, tumor tissues and intracellular environments, DOX@MSN-CD-PEG, a stepwise-acid-active organic/inorganic hybrid drug delivery system (DDS) was reported in this article. The inorganic mesoporous silica nanoparticle (MSN) was introduced for loading of doxorubicin hydrochloride (DOX). Then organic components were applied to achieve the stepwise-acid-active intracellular drug release: MSN was capped with a β -cyclodextrine ( β -CD) based host-guest system via pH-sensitive epoxy bond. Then PEG was grafted outside of the carriers through pH-sensitive benzoic imine bond. With the protection of PEG layer, the carriers were difficult cellular uptake by normal cells but could be “acid-activated” for cytophagy by cancer cells in the slightly acidic environments in tumor tissues because of the abscission of PEG. Inside the cells, the more acidic environments could further “activate” the carriers to release DOX as the leaving of the host-guest system. The fabrication processes of DOX@MSN-CD-PEG were monitored. And the stepwise-acid-active property of which was investigated by acid-triggered PEG abscission studies and in vitro drug release studies at pH 7.4 and 6.5, respectively. The in vitro cellular cytotoxicity and cellular uptake behavior were also investigated. In summary, the stepwise-acid-active hybrid DDS should be considerable for cancer therapy. [ABSTRACT FROM AUTHOR]

Mesoporous silica nanoparticles (MSN) have several advantages as carriers for drug delivery, including high drug loading capacity, good biocompatibility, excellent stability, and easily tailorable surface properties. This study describes the design of an MSN-based carrier for use in a heat shock responsive drug delivery system. MSN were functionalized with the temperature-sensitive PEG/PCL multiblock copolymer, as gatekeepers, allowing the release of entrapped drugs in response to heat shock stimuli (MBC-MSN). In the absence of heat shock, doxorubicin (Dox)-loaded MBC-MSN showed very low cytotoxicity, as PEG/PCL inhibited the premature release of Dox from MBC-MSN. In response to heat-shock stimuli, however, these Dox@MBC-MSN showed significant cytotoxicity, similar to that of free Dox. Dox release was due to the loosening of the structure of the gatekeeper, PEG/PCL, in response to the heat shock stimuli. Taken together, these findings suggest that MBC-MSN are a strong candidate to act as a carrier in heat shock responsive drug delivery. [ABSTRACT FROM AUTHOR]

Amino-functionalized mesoporous silica nanoparticles (MSN-NH2) were synthesized by a post-grafting method and further studied as carriers for doxorubicin hydrochloride (DOX) delivery. The morphology, structure, and property of MSN-NH2 and DOX-loaded MSN-NH2 (DOX@MSN-NH2) were studied using various techniques, such as transmission electron microscopy, Fourier transformed infrared spectroscopy, N2 adsorption-desorption isotherms, and zeta potentials. The drug loading and release profile as well as the in vitro cell cytotoxicity were detaily investigated. The results indicated that the loading content of DOX increased with the decrease of MSN-NH2/DOX mass ratio and/or the increase of amino density. DOX@MSN-NH2 exhibited a pH-dependent drug release, drug release increased as the pH value decreased. Compared with MSN-NH2, which were neglectable cytotoxicity against non-small-cell lung cancer (A549) cells, DOX@MSN-NH2 displayed remarkable cytotoxicity toward A549 cells in dose- and time-dependent manners. It was concluded that the as-synthesized MSN-NH2 could be used as promising drug carriers for cancer therapy. [ABSTRACT FROM AUTHOR]

Mesoporous silica nanoparticles (MSNs) are known as carriers with high loading capacity and large functionalizable surface area for target-directed delivery. In this study, a series of docetaxel-loaded folic acid- or methionine-functionalized mesoporous silica nanoparticles (DTX/MSN-FA or DTX/MSN-Met) with large pores and amine groups at inner pore surface properties were prepared. The results showed that the MSNs were successfully synthesized, having good pay load and pH-sensitive drug release kinetics. The cellular investigation on MCF-7 cells showed better performance of cytotoxicity and cell apoptosis and an increase in cellular uptake of targeted nanoparticles. In vivo fluorescent imaging on healthy BALB/c mice proved that bare MSN-NH2 are mostly accumulated in the liver but MSN-FA or MSN-Met are more concentrated in the kidney. Importantly, ex vivo fluorescent images of tumor-induced BALB/c mice organs revealed the ability of MSN-FA to reach the tumor tissues. In conclusion, DTX/MSNs exhibited a good anticancer activity and enhanced the possibility of targeted drug delivery for breast cancer. [ABSTRACT FROM AUTHOR]

Central nervous system (CNS) drug delivery is often hampered due to the insidious nature of the blood-brain barrier (BBB). Nose-to-brain delivery via olfactory pathways have become a target of attention for drug delivery due to bypassing of the BBB. The antioxidant properties of phytochemicals make them promising as CNS active agents but possess poor water solubility and limited BBB penetration. The primary aim of this study was the development of mesoporous silica nanoparticles (MSNs) loaded with the poorly water-soluble phytochemicals curcumin and chrysin which could be utilised for nose-to-brain delivery. We formulated spherical MSNP using a templating approach resulting in ∼220 nm particles with a high surface porosity. Curcumin and chrysin were successfully loaded into MSNP and confirmed through Fourier transformation infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and HPLC approaches with a loading of 11–14% for curcumin and chrysin. Release was pH dependant with curcumin demonstrating increased chemical stability at a lower pH (5.5) with a release of 53.2% ± 2.2% over 24 h and 9.4 ± 0.6% for chrysin. MSNP were demonstrated to be non-toxic to olfactory neuroblastoma cells OBGF400, with chrysin (100 μM) demonstrating a decrease in cell viability to 58.2 ± 8.5% and curcumin an IC 50 of 33 ± 0.18 μM. Furthermore confocal microscopy demonstrated nanoparticles of <500 nm were able to accumulate within cells with FITC-loaded MSNP showing membrane localised and cytoplasmic accumulation following a 2 h incubation. MSNP are useful carriers for poorly soluble phytochemicals and provide a novel vehicle to target and deliver drugs into the CNS and bypass the BBB through olfactory drug delivery. [ABSTRACT FROM AUTHOR]

The preparation of the ideal smart drug-delivery systems were successfully achieved by the in situ co -polymerization of a vinyl group-functionalized mesoporous silica nanoparticle (f-MSN) with 1-butyl-3-vinyl imidazolium bromide (BVIm) and N -isopropylacrylamide ( N IPAAm) monomers. The thickness of the capping copolymer layer, poly( N IPAAm- co -BVIm) ( p - N IBIm), was controlled at between 2.5 nm and 5 nm, depending on the monomers/f-MSN ratio in the reaction solution. The finally obtained smart drug-delivery systems are named as p-MSN2.5 and p-MSN5.0 (MSNs integrated by 2.5 nm and 5 nm p - N IBIm layer in thickness). The key roles of the mesoporous-silica-nanoparticle (MSN) core and the p - N IBIm shell are drug-carrying (or containing) and pore-capping, respectively, and the latter has an on/off function that operates in accordance with temperature changes. According to the swelling- or shrinking-responses of the smart capping copolymer to temperature changes between 10 °C and 40 °C, the loading and releasing patterns of the model drug cytochrome c were studied in vitro . The developed system showed interesting performances such as a cytochrome-c-loading profile (loading capacity for 3 h = 26.3% and 19.8% for p-MSN2.5 and p-MSN5.0, respectively) at 10 °C and a cytochrome-c-releasing profile (releasing efficiency = > 95% within 3 days and 4 days for p-MSN2.5 and p-MSN5.0, respectively) at 40 °C. The cytotoxicity of the drug delivery systems, p-MSN2.5 and p-MSN5.0 (in the concentration range of <0.125 mg/mL without drug), for human embryonic kidney (HEK 293) cells were minimal in vitro compared with that of a blank MSN. These results may be reasonably applied in the field of specified drug delivery. [ABSTRACT FROM AUTHOR]

Novel bilayer coated mesoporous silica nanoparticle (MCM-41) based on pH sensitive poly(acrylic acid-co-itaconic acid) and human serum albumin (HSA) was designed for controlled delivery of gemcitabine (anticancer drug) to cancer cells. The shell around the mesoporous silica has bilayer structure. Poly(acrylic acid-co-itaconic acid) was used as pH-sensitive inner shell and human serum albumin, HSA, was used as outer shell. The core–shell structure was formed due to electrostatic interaction between ammonium groups of modified MCM-41 and carboxylate groups of copolymer. Also, the albumin layer was wrapped around the copolymer coated nanoparticle by electrostatic interaction between ammonium groups from protein and carboxylate ions of copolymer shell. Moreover, the maximum release occurred at pH 5.5 (pH of endosomes) because the bilayer shell collapsed at this pH. The drug nanocarrier would be a good candidate for tumor therapy due to its biocompatibility, controlled release and pH responsive behavior. [ABSTRACT FROM AUTHOR]

Targeted delivery of anticancer agents by functional nanoparticles is an attractive strategy to increase their therapeutic efficacy while reducing toxicity. In this work, doxorubicin (DOX)-loaded mesoporous silica nanoparticles (MSNs) were modified with aptamer (Ap) against the epithelial cell adhesion molecule (EpCAM) for targeted delivery of DOX to colon cancer cells. These nanoparticles (Ap-MSN-DOX) were characterized by particle size, zeta potential, aptamer conjugation efficiency, drug encapsulation efficiency, and drug release properties. The in vitro cell recognition, cellular uptake, EpCAM protein inhibition efficiency, and cytotoxicity of Ap-MSN-DOX were also studied. Results demonstrated that EpCAM conjugation increased binding of Ap-MSN-DOX to EpCAM over-expressing SW620 colon cancer cells but not EpCAM-negative Ramos cells, resulting in enhanced cellular uptake and increased cytotoxicity of the DOX in SW620 cells when compared to non-Ap-modified nanoparticles (MSN-DOX). Additionally, Ap-MSN-DOX exhibited significant inhibition effects on the expression of EpCAM on SW620 cells. These results suggested that Ap-MSN-DOX has the potential for the targeted delivery of therapeutic agents into EpCAM positive colon cancer cells to improve therapeutic index while reducing side effects. [ABSTRACT FROM AUTHOR]

Can micelles be served as gating agents and fluorescent labels? Can a drug delivery system be constructed by combining two kinds of drug carriers, such as mesoporous silica nanoparticles and micelles? Will the combination be better or worse? To settle these questions, we designed and constructed a nanocarrier by cooperating two kinds of drug carriers (mesoporous silica nanoparticles and F127 micelles), providing a suitable method for the design of multifunctional stimuli-responsive drug delivery and self-fluorescent imaging systems. The system is fabricated using anticancer drug (curcumin) loaded micelles (CF127) as gating agents and fluorescent labels of mesoporous silica nanoparticles via Schiff base. Because of the pH-sensitive Schiff base, the gating micelles can achieve drug release under acidic condition, while preventing the drug release under natural condition. Moreover, due to the aggregation of CF127 micelles on the surface of mesoporous silica nanoparticles, the fluorescent intensity of CF127 micelles is significantly enhanced. Furthermore, CF127 micelles exhibit good anti-photobleaching property, indicating that the system here is promising for noninvasive in vivo tracking the delivery of therapeutic agents. The cooperation of two kinds of drugs in anti-cancer application and the easily further modification ability of the system is also be confirmed. These results indicate that this study paves the way for a generation of drug delivery systems and could provide a general route to prepare multifunctional biocompatible platforms for biomedical imaging diagnosis and simultaneous therapy for lesion sites such as cancers. [ABSTRACT FROM AUTHOR]

Surface modified mesoporous silica nanoparticles (MSNs) with reduced toxicity were prepared for light and pH dual triggerable drug delivery system. Both 413 nm light and acidic environment can activate the drug release process, improving the pharmacological action. By applying rhodamine B (RhB) as a model drug, the accumulative RhB release is as high as 95% in pH 5.0 and in irradiation of 413 nm light, compared to only 55% in pH 7.4 and in dark. The anti-cancer drug camptothecin (CPT) loaded nanoparticles can kill cancer cells with IC 50 value of 0.02 μg mL −1 in exposure of 413 nm light, which is much lower than free CPT (about 0.1 μg mL −1 ). Multimodal nonlinear optical imaging microscopy (NLOM) was employed to acquire in vitro coherent anti-Stokes Raman (CARS) and two-photon excited fluorescence (TPEF) images of live MCF-7 cells and showed that the nanoparticles can be taken up by breast tumor cell MCF-7 with high efficiency, indicating its great potential for anti-cancer drug delivery system. [ABSTRACT FROM AUTHOR]

A facile method is described to prepare pH-sensitive and self-fluorescent drug delivery systems using mesoporous silica nanoparticles and PAMAM dendrimers, providing a general route to develop multifunctional and biocompatible platforms, which integrated increasing the number of reaction sites, retaining drug molecules, controlling drug delivery behaviour and fluorescent imaging into one carrier system, for biomedical imaging diagnosis and simultaneous therapy for lesion sites such as cancers. [ABSTRACT FROM AUTHOR]

Synthesis of novel drug delivery system for targeted delivery of cuminaldehyde to breast cancer cells and the subsequent analyses of anti-neoplastic potential of the drug. 3-carboxy-phenyl boronic acid (PBA) conjugated and polyacrylic acid (PAA) gated mesoporous silica nanoparticles (MSNs) were synthesized for the targeted delivery of cuminaldehyde (CUM) to breast cancer cells. Enhancement of anti-neoplastic effects of cuminaldehyde (4-isopropylbenzaldehyde) by the nanoconjugates was assessed. The anti-cancer effects of non-targeted and targeted drug-nanoconjugates were examined in vitro and in vivo. The targeted drug-nanoconjugates caused cell cycle arrest and induced the intrinsic pathway of apoptosis in MCF-7 cells through mitochondrial damage. In vivo intravenous injection of the targeted drug-nanoconjugates led to effective reduction in growth of 4 T1 induced mammary pad tumor in female BALB/c mice via augmented accumulation of cuminaldehyde. The drug-nanoconjugates did not exhibit any systemic toxicity. Therefore, MSN-PBA-CUM-PAA represents a potent therapeutic model for breast cancer treatment. [Display omitted] • For the first time, PBA functionalized PAA coated MSNs have been synthesized. • Targeted delivery was achieved through the binding of PBA to poly-sialic acid residues on the surface of the cancer cells. • PAA gating on nanoformulations conferred pH-responsive release of cuminaldehyde in cancer cells. • MSN-PBA-CUM-PAA exhibited significant anti-neoplastic effects both in vitro and in vivo. • The nanocarriers did not exhibit any systemic toxicity. [ABSTRACT FROM AUTHOR]

Traditional treatment of cancers such as chemotherapy still causes many side effects after the treatment even nowadays, therefore combination therapies by using drug delivery systems are valued by more and more scientists. However, loading multiple drugs in the nanoparticles for drug delivery system may cause insufficient drugs or functional groups, which might let the nanomaterial have fewer functions. Therefore, making the mesoporous silica nanoparticles (MSNs) have photodynamic therapy function by "doping " lanthanide ions into the material structure, can evade this problem. Moreover, with the doping of lanthanide metals, the MSNs can have not only dual imaging functions of both magnetic resonance imaging and fluorescence, but also achieve photodynamic function. To feature the material with more function, chemotherapeutic drug-doxorubicin was loaded into the pores of MSNs and then bonded hyaluronic acid which is the active target and a gatekeeper, on the surface of MSNs. Finally, an all-in-one drug delivery system" Hyaluronidase and pH-responsive mesoporous silica nanoparticles with dual-imaging activity for chemo-photodynamic therapy" is synthesized. The first part in this experiment was to confirm the physical properties of the lanthanides dopped MSN and its photodynamic treatment effect. The second part was to confirm that each organic molecule had been successfully bonded to the surface of the MSN and achieve pH and Hyaluronidase response drug release effect, The last part was to prove that the drug delivery system had a significant anticancer effect through cell experiments. The intracellular hyaluronidase will decompose hyaluronic acid on the surface of carrier to release doxorubicin and further released due to the lower pH in the cancer cell. Then, tumor is irradiated with near-infrared light so that the drug carrier produce Reactive oxygen species and increase the anticancer effect. [Display omitted] • This material successfully combines chemotherapy and photodynamic therapy. • The system has targeted, dual imaging and dual drug controlled release functions. • The drug will release due to the lower pH and higher hyaluronidase concentration. • The material demonstrating the fluorescent and magnetic imaging function. • Synergistic effect was performed in this drug delivery system. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes the fabrication of a highly efficient, non-cytotoxic drug delivery platform designed for photodynamic therapy (PDT): phospholipid-capped, protoporphyrin IX–loaded and FITC-sensitized mesoporous silica nanocarriers (Lipo-FMSNs/PpIX). After derivatization with folate on the phospholipid-capped FMSNs (denoted fa-Lipo-FMSNs/PpIX, the so-called nanoPDT system), we confirmed the nanoPDT systems' selective targeting of and entry into the folic acid receptor-overexpressed HeLa cells by means of cell viability assessment and confocal microscopic analysis. The decrease in the unfavorable dark toxicity of fa-Lipo-FMSNs/PpIX enabled the delivery of high concentrations of PpIX into cells. Moreover, the cellular uptake of the nanoPDT systems was greater than that of free PpIX. Upon irradiation with visible light, the nanoPDT system generated singlet oxygen efficaciously in aqueous environments—a decisive factor affecting its therapeutic applicability in PDT, demonstrating enhanced in vitro photocytotoxicity. Furthermore, an in vivo study of subcutaneous melanoma in nude mice inoculated with B16F10 cells revealed the capability for the nanoPDT system to mitigate nearly 65% of tumor growth. [Copyright &y& Elsevier]

Abstract: A novel reduction-responsive drug delivery system was successfully constructed with mesoporous silica nanoparticle (MSN) core as a drug carrier and poly(acrylic acid) (PAA) shell crosslinked by disulfide linkages as a drug release switcher. To keep the pore structure of MSN intact, PAA was covalently attached to the exterior surface of MSN before removing structure-template via radical polymerization. After removing structure-template and loading doxorubicin (DOX), the PAA shell was crosslinked by cystamine dihydrochloride through amidation reaction. The loading content and the entrapment efficiency of DOX could reach up to 40.2% and 80.4%, respectively. Because that the dissociation of disulfide linkage is reduction-responsive, the release behavior of DOX could be controlled by varying the concentration of reductant, and the release rate was 49.4% after 24h with the existence of 2mM glutathione (simulated environment of cancer cells), about three times higher than that of without glutathione (corresponding to normal human cells), which was only 16.9%. The in vitro cell assays demonstrated that the disulfide linkages crosslinked MSN–PAA (MSN–PAA-crosslinked) was highly biocompatible and suitable to use as drug carrier, and the DOX loaded MSN–PAA-crosslinked showed remarkable cytotoxicity to HeLa cells (human cancer cells), and relatively lower cytotoxicity to 293 cells (human normal cells). These results imply that the MSN–PAA-crosslinked is a promising platform to construct reduction-responsive controlled drug delivery system for cancer therapy. [Copyright &y& Elsevier]

This pHLIP is no flop: Functionalizing mesoporous silica nanoparticles (MSNs) with pHLIPss peptide provides a controlled‐release nanoparticle drug delivery system targeting the acidic tumor microenvironment. At low pH values, pHLIPss inserts into the cell membrane and translocates carriers into cells, where the cargo is released by the cleavage of the pHLIPss disulfide bonds (see scheme). [ABSTRACT FROM AUTHOR]

Abstract: pH-sensitive poly(l-glutamic acid) grafted mesoporous silica nanoparticles (MSN-PLGA) were prepared by the surface-initiated N-carboxyanhydride polymerization method. The resultant MSN-PLGA was well dispersed in aqueous medium and showed high drug loading efficiency, superior stability, and significantly higher drug release rates. The cumulative release of doxorubicin hydrochloride (DOX) from DOX-loaded MSN-PLGA (DOX@MSN-PLGA) was pH-dependent and the release rate was much higher at pH 5.5 than that at pH 7.4. The cytotoxicity results indicated that the blank MSN-PLGA was biocompatible and the DOX@MSN-PLGA had potent in vitro cytotoxicity effect similar to free DOX. Overall, these results demonstrate that MSN-PLGA is a promising platform to build pH controlled drug delivery systems for cancer therapy. [Copyright &y& Elsevier]

The fabrication of photo-degradable, protein-polyelectrolyte complex (PPC)-coated, mesoporous silica nanoparticles (MSNs) and their controlled co-release of protein and model drugs is reported. Random copolymers composed of oligo(ethylene glycol) monomethyl ether methacrylate (OEGMA), and a photolabile o-nitrobenzyl-containing monomer, 5-(2′-(dimethylamino)ethoxy)-2-nitrobenzyl methacrylate (DENBMA), are first anchored onto the MSNs and then quaternary aminated, to obtain positively charged P(OEGMA- co-TENBMA) which exhibits photo-induced charge conversion characteristics. PPCs consisting of P(OEGMA- co-TENBMA) and the protein bovine serum albumin (BSA) are utilized as capping agents for the nanopores of the MSNs. Upon UV irradiation, charge conversion of P(OEGMA- co-TENBMA) can lead to the disruption of PPCs on MSNs and co-release of BSA and rhodamine B by electrostatic repulsion. [ABSTRACT FROM AUTHOR]

Drug molecules with lack of specificity and solubility lead patients to take high doses of the drug to achieve sufficient therapeutic effects. This is a leading cause of adverse drug reactions, particularly for drugs with narrow therapeutic window or cytotoxic chemotherapeutics. To address these problems, there are various functional biocompatible drug carriers available in the market, which can deliver therapeutic agents to the target site in a controlled manner. Among the carriers developed thus far, mesoporous materials emerged as a promising candidate that can deliver a variety of drug molecules in a controllable and sustainable manner. In particular, mesoporous silica nanoparticles are widely used as a delivery reagent because silica possesses favourable chemical properties, thermal stability and biocompatibility. Currently, sol-gel-derived mesoporous silica nanoparticles in soft conditions are of main interest due to simplicity in production and modification and the capacity to maintain function of bioactive agents. The unique mesoporous structure of silica facilitates effective loading of drugs and their subsequent controlled release. The properties of mesopores, including pore size and porosity as well as the surface properties, can be altered depending on additives used to fabricate mesoporous silica nanoparticles. Active surface enables functionalisation to modify surface properties and link therapeutic molecules. The tuneable mesopore structure and modifiable surface of mesoporous silica nanoparticle allow incorporation of various classes of drug molecules and controlled delivery to the target sites. This review aims to present the state of knowledge of currently available drug delivery system and identify properties of an ideal drug carrier for specific application, focusing on mesoporous silica nanoparticles. [ABSTRACT FROM AUTHOR]

Abstract: Most pH-sensitive drug delivery systems have been reported to respond to wide ranges of pH or target tissues the pH of which vary considerably, whereas these systems are not able to target diseased tissues like inflammatory tissues and tumor cells (pH 6.8) due to the extremely slight differences between pH of normal tissues (pH 7.4) and them. Consequently, ingenious pH-responsive drug delivery systems are desired to target this kind of abnormal tissues. In the present study, we fabricated a novel pH-sensitive drug delivery system with a 22% loading capacity, which released about 65% and 35% model drug in pH 6.8 and 7.4 after 24h, respectively. In pH 7.4 release medium, chitosan molecules are orderly aggregated state, which efficiently hinder the release of the guest molecules from nanocarriers. However, in pH 6.8 release medium, chitosan chains are heavily and flexibly entangled in gel state, which is good for the release of guest molecules. The drug delivery system could reduce the drug nonspecific reaction with normal cells but remaining the curative effect. [Copyright &y& Elsevier]

Abstract: pH-responsive polymer shell chitosan/poly (methacrylic acid) (CS-PMAA) was coated on mesoporous silica nanoparticles (MSN) through the facile in situ polymerization method. The resultant composite microspheres showed a flexible control over shell thickness, surface charges and hydrodynamic size by adjusting the feeding amount of MSN and the molar ratio of [–NH2]/MAA. The MSN/CS-PMAA composite microspheres were stable in the pH range of 5–8 as well as in the physiological saline (0.15M NaCl). Doxorubicin hydrochloride (DOX) was applied as a model drug to investigate the drug storage and release behavior. The results demonstrated that DOX could be effectively loaded into the composite microspheres. The cumulative release of DOX-loaded composite microspheres was pH dependent and the release rate was much faster at low pH (5.5) than that of pH 7.4. The cytotoxicity test by MTT assay showed that the blank carrier MSN/CS-PMAA microspheres were suitable as drug carriers. The cellular uptake of composite microspheres was investigated by confocal laser scanning microscopy (CLSM), which indicated that MSN/CS-PMAA could deliver the drugs into HeLa cell. The above results imply that the composite microspheres are a promising drug delivery system for cancer therapy. [Copyright &y& Elsevier]

Mesoporous silica nanoparticles incorporating zinc(II) phthalocyanine and Fe3O4 (ZnPc/Fe3O4/MSN) were synthesized via a simple one-pot procedure. The nanoparticles showed appropriate magnetic and optical characteristics for both magnetic resonance imaging and photodynamic therapy. The ZnPc/Fe3O4/MSN also offered the possibility of the controlled release of drugs. The change in the surface and pore structure that result from the presence of Fe3O4 and zinc(II) phthalocyanine modified the drug release kinetics beneficially. [Copyright &y& Elsevier]

Low water solubility and thus low bioavailability limit the clinical application of fenbendazole (FBZ) as a potential anticancer drug. Solubilizing agents, such as Mobil Composition of Matter Number 41 (MCM) as a drug carrier, can improve the water solubility of drugs. In this study, PEGylated MCM (PEG-MCM) nanoparticles (NPs) were synthesized and loaded with FBZ (PEG-MCM-FBZ) to improve its solubility and, as a result, its cytotoxicity effect against human prostate cancer PC-3 cells. The loading efficiency of FBZ onto PEG-MCM NPs was 17.2%. The size and zeta potential of PEG-MCM-FBZ NPs were 366.3 ± 6.9 nm and 24.7 ± 0.4 mV, respectively. They had a spherical shape and released the drug in a controlled manner at pH 1.2 and pH 6.2. PEG-MCM-FBZ were found to inhibit the migration of PC-3 cells, increase the cytotoxicity effects of FBZ against PC-3 cells by 3.8-fold, and were more potent by 1.4-fold, when compared to the non-PEGylated NPs. In addition, PEG-MCM-FBZ promoted the production of reactive oxygen species by 1.3- and 1.2-fold, respectively, when compared to FBZ and MCM-FBZ. Overall, the results demonstrate that PEG-MCM-FBZ NPs enhanced FBZ delivery to PC-3 cells; therefore, they have the potential to treat prostate cancer after a comprehensive in vivo study. [ABSTRACT FROM AUTHOR]

This review details the recent advancements in the design of mesoporous silica nanomaterials for controlled release drug, gene and neurotransmitter delivery applications. The high surface area (>900 m2/g), tunable pore diameter (2-20 nm) and uniform mesoporous structure (hexagonal channels or cubic pores) of the mesoporous silicas offer a unique advantage for loading and releasing large quantities of biomedical agents. Recent breakthroughs in controlling the particle size and shape of these materials have greatly improved the biocompatibility and the cellular uptake efficiency. The strategy of using various removable capping moieties, such as photo- or redox-responsive organic groups, inorganic nanoparticles, dendrimers and polymers, to encapsulate guest biomolecules inside the porous matrices further enables the utilization of these surfacefunctionalized mesoporous silica nanomaterials for stimuli-responsive controlled release in vitro and in vivo. In addition to the reviewed studies, many new and exciting applications of these novel materials will soon be realized. [ABSTRACT FROM AUTHOR]