Surface Of Mesoporous Silica Nanoparticles Research Articles

Adsorption and Release of Sulfamethizole from Mesoporous Silica Nanoparticles Functionalised with Triethylenetetramine.

Mesoporous silica nanoparticles (MSN) were synthesised and functionalised with triethylenetetramine (MSN-TETA). The samples were fully characterised (transmission electron microscopy, small angle X-ray scattering, Fourier transform infrared spectroscopy, thermogravimetric analysis, zeta potential and nitrogen adsorption/desorption isotherms) and used as carriers for the adsorption of the antimicrobial drug sulphamethizole (SMZ). SMZ loading, quantified by UV–Vis spectroscopy, was higher on MSN-TETA (345.8 mg g−1) compared with bare MSN (215.4 mg g−1) even in the presence of a lower surface area (671 vs. 942 m2 g−1). The kinetics of SMZ adsorption on MSN and MSN-TETA followed a pseudo-second-order model. The adsorption isotherm is described better by a Langmuir model rather than a Temkin or Freundlich model. Release kinetics showed a burst release of SMZ from bare MSN samples (k1 = 136 h−1) in contrast to a slower release found with MSN-TETA (k1 = 3.04 h−1), suggesting attractive intermolecular interactions slow down SMZ release from MSN-TETA. In summary, the MSN surface area did not influence SMZ adsorption and release. On the contrary, the design of an effective drug delivery system must consider the intermolecular interactions between the adsorbent and the adsorbate.

SERS Sensors Based on Aptamer-Gated Mesoporous Silica Nanoparticles for Quantitative Detection of Staphylococcus aureus with Signal Molecular Release.

This work describes a simple and novel biosensor for the quantitative determination of Staphylococcus aureus (S. aureus) based on target-induced release of signal molecules from aptamer-gated aminated mesoporous silica nanoparticles (MSNs) coupled with surface-enhanced Raman scattering (SERS) technology. MSNs were synthesized and then modified with amino groups by (3-aminopropyl) triethoxysilane to make them positively charged. Next, signal molecules (4-aminothiophenol, 4-ATP) were loaded into the pores of MSNs. Then, negatively charged aptamers of S. aureus were assembled on the surface of MSNs through electrostatic interactions. Upon the addition of S. aureus, the assembled aptamers were specifically bound to the bacteria. Consequently, the "gates" were opened, resulting in the release of 4-ATP from the pores of MSNs. The released molecules were measured by a Raman spectrometer, and the intensity of 4-ATP at 1071 cm-1 was linearly related to the S. aureus concentration. A silver nanoflower silica core-shell structure (Ag NFs@SiO2) was prepared and it served as a SERS substrate. Under optimized experimental conditions, a good linear relationship (y = 2107.93 + 1536.30x, R2 = 0.9956) in the range from 4.7 × 10 to 4.7 × 108 cfu/mL was observed with a limit of detection of 17 cfu/mL. The method was successfully applied for the analysis of S. aureus in fish samples and the recovery rate was 91.3-109%.

DNA-Directed Assembly of a Cell-Responsive Biohybrid Interface for Cargo Release.

The development of a DNA-based cell-responsive biohybrid interface that can be used for spatially confined release of molecular cargo is reported. To this end, tailored DNA-protein conjugates are designed as gatekeepers that can be specifically cleaved by matrix metalloproteases (MMPs), which are secreted by many cancer cells. These gatekeepers can be installed by DNA hybridization on the surface of mesoporous silica nanoparticles (MSNs). The MSNs display another orthogonal DNA oligonucleotide that can be exploited for site-selective immobilization on solid glass surfaces to yield micropatterned substrates for cell adhesion. Using the human fibrosarcoma cell line HT1080 that secretes MMPs, it is demonstrated that the biohybrid surface is specifically modified by the cells to release both MSN-bound gatekeeper proteins and the encapsulated cargo peptide KLA. In view of the enormously high modularity of the system presented here, this approach promising for applications in drug delivery, tissue engineering, or other areas of nanobiotechnology is considered.

Fabrication of pH-responsive nanoparticles for high efficiency pyraclostrobin delivery and reducing environmental impact

In this work, a pH-responsive pesticide delivery system using mesoporous silica nanoparticles (MSNs) as the porous carriers and coordination complexes of Cu ions and tannic acid (TA-Cu) as the capping agent was established for controlling pyraclostrobin (PYR) release. The results showed the loading capacity of PYR@MSNs-TA-Cu nanoparticles for pyraclostrobin was 15.7 ± 0.5% and the TA-Cu complexes deposited on the MSNs surface could protect pyraclostrobin against photodegradation effectively. The nanoparticles had excellent pH responsive release performance due to the decomposition of TA-Cu complexes under the acid condition, which showed 8.53 ± 0.37%, 82.38 ± 1.67% of the encapsulated pyraclostrobin were released at pH 7.4, pH 4.5 after 7 d respectively. The contact angle and adhesion work of PYR@MSNs-TA-Cu nanoparticles on rice foliage were 86.3° ± 2.7° and 75.8 ± 3.1 mJ/m2 after 360 s respectively, indicating that TA on the surface of the nanoparticles could improve deposition efficiency and adhesion ability on crop foliage. The control effect of PYR@MSNs-TA-Cu nanoparticles against Rhizoctonia solani with 400 mg/L of pyraclostrobin was 85.82% after 7 d, while that of the same concentration of pyraclostrobin EC was 53.05%. The PYR@MSNs-TA-Cu nanoparticles did not show any phytotoxicity to the growth of rice plants. Meanwhile, the acute toxicity of PYR@MSNs-TA-Cu nanoparticles to zebrafish was decreased more than 9-fold compared with that of pyraclostrobin EC. Thus, pH-responsive PYR@MSNs-TA-Cu nanoparticles have great potential for enhancing targeting and environmental safety of the active ingredient.

Targeted delivery system using silica nanoparticles coated with chitosan and AS1411 for combination therapy of doxorubicin and antimiR-21

Herein, a novel targeted delivery system was developed for intracellular co-delivery of doxorubicin (DOX) as a chemotherapeutic drug, antimiR-21 as an oncogenic antagomiR. In this system, DOX was loaded into mesoporous silica nanoparticles (MSNs) and chitosan was applied to cover the surface of MSNs. AS1411 aptamer as targeting nucleolin and antimiR-21 were electrostatically attached onto the surface of the chitosan-coated MSNs and formed the final nanocomplex (AACS nanocomplex). The study of drug release was based on DOX release under pH 7.4 and 5.5. Cellular toxicity and cellular uptake assessments of AACS nanocomplex were carried out in nucleolin positive (C26, MCF-7, and 4T1) and nucleolin negative (CHO) cell lines using MTT assay and flow cytometry analysis, respectively. Also, Anti-tumor efficacy of AACS nanocomplex was evaluated in C26 tumor-bearing mice. Overall, the results show that the combination therapy of DOX and antimiR-21, using AACS nanocomplex, could combat the cancer cell growth rate.

Chitosan-glucuronic acid conjugate coated mesoporous silica nanoparticles: A smart pH-responsive and receptor-targeted system for colorectal cancer therapy

Glycosylated pH-sensitive mesoporous silica nanoparticles (MSNs) of capecitabine (CAP) were developed for targeting colorectal cancer. The MSNs possessed an average pore diameter of 8.12 ± 0.43 nm, pore volume of 0.73 ± 0.21 cm3/g, and particle size of 245.24 ± 5.75 nm. A high loading of 180.51 ± 5.23 mg/g attributed to the larger pore volume was observed. The surface of the drug-loaded MSNs were capped with chitosan-glucuronic acid (CHS-GCA) conjugate to combine two strategies viz. pH-sensitive, and lectin receptor mediated uptake. In vitro studies demonstrated a pH-sensitive and controlled release of CAP which was further enhanced in the presence of rat caecal content. Higher uptake of the (CAP-MSN)CHS-GCA was observed in HCT 116 cell lines. The glycosylated nanoparticles revealed reduction in the tumors, aberrant crypt foci, dysplasia and inflammation, and alleviation in the toxic features. This illustrated that the nanoparticles showed promising antitumor efficacy with reduced toxicity and may be used as a effective carrier against cancer.

A bolt-like-blocking nanovalve on mesoporous silica nanoparticles for controlled release

A novel bolt-like-blocking nanovalve based on mesoporous silica nanoparticles (MSNs) has developed as a drug carrier, using the modified short peptide as a support and the delivery drug as a bridge for fulfilling the blocking process. The peptide-modified nanoparticle MSN-S-S-NAC-Trp combined with the loaded drug can be used as a carrier with no leakage and be triggered for release by appropriate GSH. The peptide-modified nanoparticles have showed no obvious cytotoxicity and can be internalized into L929 cells; moreover, the doxorubicin loaded nanoparticles incubated with HeLa cells have showed GSH-responsive capability and induced cell apoptosis. Since the chain of the modified peptide on the surface of MSN is not long enough to block the channel via self-assembly process, a bolt-like-blocking model is proposed.

A carboxymethyl lentinan layer by layer self-assembly system as a promising drug chemotherapeutic platform

Surface functionalization of mesoporous silica nanoparticles (MSNs) has been proposed as an efficient strategy for enhancing the biocompatibility and efficiency of an MSN-based carrier platform. Herein, natural polyelectrolyte multilayers composed of poly-l-ornithine (PLO) and carboxymethyl lentinan (LC) were coated on the surface of MSNs through a layer-by-layer (LbL) self-assembly technique, and were characterized by ζ-potential, FTIR, 13C NMR, SEM, TEM, XRD, and TG. The prepared carrier presented alternating positive and negative potentials when coated with the polyelectrolytes, and the surface of MSN-PLO/LC was rougher compared to the naked MSNs. The biocompatibility tests, including cytocompatibility, hemocompatibility, and histocompatibility, showed that MSNs biocompatibility could be improved by modifying LC. A high loading and sustained release drug delivery system was constructed after loading doxorubicin (DOX) into the prepared MSN-PLO/LC, which exhibited significant anti-proliferative efficiency in human cervical cancer cell lines (Hela). Therefore, the PLO/LC LbL NPs (layer-by-layer self-assembled nanoparticles coated with PLO/LC layers) based on MSNs, which is easily prepared by electrostatic interactions, can be considered a promising drug chemotherapeutic platform and delivery technique for future human cervical cancer therapy.

Cysteine- and glycine-functionalized mesoporous silica as adsorbents for removal of paracetamol from aqueous solution

ABSTRACT The presence of pharmaceutical compounds in the environment is problem for human health worldwide. Paracetamol is one of the pharmaceutical compounds that is widely used as a pain reliever and fever reducer, and it has been discharged in water via industrial and domestic wastewater. This study aimed to improve the removal of paracetamol from aqueous solutions using two different amino-acid-modified mesoporous silica nanoparticles (MSNs). Two types of adsorbents were used: the surfaces of epoxy-modified MSNs were modified with glycine (MSN-Gly) and cysteine (MSN-Cys). Topographical images indicated that the size of fabricated nanoparticles ranged between 220 and 360 nm, with a pore size of ~5 nm. IR spectra confirmed the successful attachment of amino acids on MSN surfaces as a peak appeared at ~1720 cm−1, indicating a carbonyl group. A series of experiments were performed using the batch adsorption method to investigate the effects of contact time, initial concentration of the adsorbate, and pH on the removal of paracetamol from the aqueous solution. The adsorption capacity of paracetamol was higher in acidic media for both adsorbents. The maximum adsorbed amount of paracetamol was 300 mg/g for MSN-Gly compared with 250 mg/g for MSN-Cys. For both adsorbents and at all pH values, the experimental data were well matched with the pseudo-second order and the adsorption isotherm was fitted using a Temkin model.

In vitro breast cancer targeting using Trastuzumab-conjugated mesoporous silica nanoparticles: Towards the new strategy for decreasing size and high drug loading capacity for drug delivery purposes in MSN synthesis

Abstract In the present study, an efficient protocol was introduced for synthesis of biocompatible mesoporous silica nanoparticles (MSN) with an adequate size and high drug loading capacity. Herein, the tri-ethanolamine, TEA, dominantly controlled the pH of solution in addition to regulate nanoparticle sizes via complexing with ortho silicate functional group. Furthermore, ammonium nitrate as a weak acid was used for micellar template extraction and the results were compared with a common salt such as sodium chloride. The obtained results of BET analysis showed ammonium nitrate led to creation of pore sizes with 3.2 nm and enhanced specific surface area with 563 m2/g which were higher than NaCl route. In the next step, the surfaces of MSNs were functionalized with particular compounds, (3- Aminopropyl) tri-ethoxysilane, APTES, applied for amine functionalization whereas 1-Ethyl-3-(3- dimethylaminopropyl)-carbodiimide/N-hydroxysuccinimide, EDC/NHS, as cross link agent was used for Trastuzumab modification of silica nanoparticles which were subsequently loaded with doxorubicin for studying the targeted breast cancer therapy. Moreover, fluorescein dye was optimized on the surface modified nanoparticles. The molecular fluorescence imaging was used to confirm the significant attachments of our surface modified MSNs to plasma membrane of breast cancer cell lines (HER2 overexpressed SKBR3 cell lines). Furthermore, drug loading capacity of the presented nano-carriers was calculated and shown to be 57.40% for doxorubicin suggesting its priority in the biological application comparing to other reported ones. Finally, quantum chemical study at B3lyp/6–311++g** level of theory was performed to reveal the pH-triggered release of doxorubicin loaded on these nanoparticles which the obtained results were in agreement with experimental evidences.

CRISPR-dCas9-Guided and Telomerase-Responsive Nanosystem for Precise Anti-Cancer Drug Delivery.

Nanodrug delivery systems are very promising for highly efficient anticancer drug delivery. However, the present nanosystems are commonly located in the cytoplasm and mediate uncontrolled release of drugs into cytosol, while a large number of anticancer drugs function more efficiently inside the nucleus. Here, we constructed a CRISPR-dCas9-guided and telomerase-responsive nanosystem for nuclear targeting and smart release of anticancer drugs. CRISPR-dCas9 technology has been employed to achieve conjugation of mesoporous silica nanoparticles (MSNs) with a high payload of the active anticancer drug, doxorubicin (DOX). A specifically designed wrapping DNA was used as a telomerase-responsive biogate to encapsulate DOX within MSNs. The wrapping DNA is extended in the presence of telomerase, which is highly activated in tumor cells, but not in normal cells. The extended DNA sequence forms a rigid hairpin-like structure and diffuses away from the MSN surface. CRISPR-dCas9 specifically targets telomere-repetitive sequences at the tips of chromosomes, facilitating the precise delivery of the nanosystem to the nucleus, and effective drug release triggered by telomerase that was enriched around telomeric repeats. This study provides a strategy and nanosystem for nuclear-targeted delivery and tumor-specific release of anticancer drugs that will maximize the efficiency of cancer cell destruction.

Cloaking mesoporous silica nanoparticles with phenylboronic acid-conjugated human serum albumin-co-polydopamine films for targeted drug delivery

Preparation of nanoparticles with stealth capabilities and active targeting abilities is still a research hot spot. In this work, non-PEGylated mesoporous silica nanoparticles (MSNs) with the property of stealth in the blood stream are prepared by immobilizing human serum albumin (HSA) and polydopamine (PDA) on the surface of MSNs to form an albumin-rich protein corona and modifying with 4-aminophenylboronic acid (PBA) to actively target the 4T1 tumor cells, namely MSN-PDA-HSA-PBA (MPHP). The MPHP exhibits much lower intake by the macrophages and achieves much better targeting efficiency toward 4T1 cells, which are evaluated by cellular uptake and targeting assay in vitro. Besides, gemcitabine (GEM) is chose as the model drug and the results of in vitro cellular cytotoxicity and apoptosis suggest that the prepared MPHP/GEM has higher antitumor efficiency in comparison to free GEM. What's more, MPHP/GEM shows better in vivo inhabitation of the growth of 4T1 tumor than MSN/GEM. Above results suggest that MPHP is a promising carrier which can be used for cancer treatment.

Cholesterol-functionalised mesoporous silica nanoparticles for removal of naphthalene from water

ABSTRACT This work introduces the synthesis of mesoporous silica nanoparticles (MSNs) with high surface area and average pore size of ca. 4 nm. MSNs were modified with amine groups and then reacted with succinic anhydride. Cholesterol was attached to MSNs surface via an esterification reaction between hydroxyl and carboxylic groups in acidic media. Thereafter, the cholesterol-functionalised MSNs were used to remove naphthalene from the water with high removal efficiency, compared to unmodified surface. The fabricated nanoparticles were analysed with some physico-chemical techniques such as transmission electron microscopy (TEM), Fourier Transform Infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA).

Evaluation of the Adsorption Efficiency of Glycine-, Iminodiacetic Acid -, and Amino Propyl-Functionalized Silica Nanoparticles for the Removal of Potentially Toxic Elements from Contaminated Water Solution

In present work, mesoporous silica nanoparticles (MSNs) were prepared with a surface area of 1048 m2g-1 and a large pore size of ca. 6 nm, using Stöber process in the presence of expanding reagent ( n -hexane). The surface of MSNs was modified with three different functional groups (amine, iminodiacetic acid, and glycine) and characterized by a variety of physicochemical techniques. The adsorption studies were carried out at different pH values in two extraction systems. In batch method, the maximum adsorption efficiency of heavy metals was measured to be 95% for all fabricated MSNs at pH 9. At pH 3, the adsorption efficiency of Pb and Cu was observed to be affected by the carboxylic moiety involved in the functional group. As the number of carboxylic moieties increase, the removal efficiency of Pb and Cu ions increased by two folds. The results demonstrated the selectivity of IDA-MSNs for the removal of Pb and Cu ions, even though the multielements are present in an aqueous solution. On the other hand, the incorporation of MSNs into the polymeric membrane showed high water permeability ( 9.96 ± 3 L / m 2 . h . bar ), and 98% rejection was achieved at pH 7 for Cu+2 and Pb+2 ions.

Development of mesoporous silica-based nanoprobes for optical bioimaging applications.

A mesoporous silica nanoparticle (MSN)-based nanoplatform has attracted growing attention in the biomedical field due to the unique characteristics of MSNs including a high surface area, tunable pore sizes, colloidal stability, ease of functionalization, and desirable biocompatibility. Typically, MSNs are designed as nanocarriers for the incorporation of a variety of contrast agents for bioimaging, which can address the intrinsic drawbacks of contrast agents, including poor solubility in water, rapid photobleaching, and low stability. This review summarizes the recent advances in the field of MSN-based nanoprobes for fluorescence imaging and photoacoustic (PA) imaging applications. The approaches for the incorporation of contrast agents into MSN-based nanoplatforms including encapsulating contrast agents within MSNs, covalently conjugating contrast agents on the surface or pores of MSNs, physically absorbing contrast agents in the pores of MSNs, and doping contrast agents in the framework of MSNs are introduced. MSN-based nanoprobes for fluorescence imaging and PA imaging are discussed. The enhanced fluorescence imaging and PA imaging performances of MSN-based nanoprobes relative to the bare contrast agents are introduced and the underlying mechanisms are discussed in detail. Finally, current challenges and perspectives of MSN-based nanoprobes in the bioimaging field are discussed.

Glycyrrhetinic Acid-Functionalized Mesoporous Silica Nanoparticles for the Co-Delivery of DOX/CPT-PEG for Targeting HepG2 Cells.

A pH-triggered mesoporous silica nanoparticle (MSN)-based nano-vehicle for the dual delivery of doxorubicin (DOX)/camptothecin-PEG (CPT-PEG) has been prepared. To enhance its selectivity, the nanoparticles were decorated with glycyrrhetinic acid (GA) to target HepG2 cells. The highly insoluble CPT was derivatized with a reductive-cleavable PEG chain to improve its loading within the MSN. The preparation of these particles consisted of four steps. First, CPT-PEG was loaded within the pores of the MSN. Then, dihydrazide polyethylene glycol chains were introduced onto the surface of an aldehyde-functionalized MSN by means of a hydrazone bond. Afterwards, DOX was covalently attached to the other end of the dihydrazide polyethylene glycol chains. Finally, the resulting nanoparticles were decorated with GA by formation of an imine bond between the amino group of DOX and a benzaldehyde-GA derivative. The system was stable at physiological conditions and the release of both drugs was negligible. However, at acidic pH, a burst release of DOX and a gradual release of CPT-PEG takes place. GA-decorated drug delivery systems (DDS) selectively internalizes into HepG2. In vitro tests demonstrated that this system shows a great cytotoxicity towards HepG2 cells. Furthermore, glutathione cleavage of CPT prodrug assures the formation of free CPT leading to a synergistic effect in combination with DOX.

Targeted delivery of curcumin in breast cancer cells via hyaluronic acid modified mesoporous silica nanoparticle to enhance anticancer efficiency

Curcumin (C) is a natural antioxidant which has many beneficial effects. However, poor bioavailability and less water solubility render it unsuitable as an anti-cancer drug. Herein, curcumin was delivered through Mesoporous silica nanoparticle (MSN) based drug delivery system to enhance its anticancer efficacy. Targeted delivery of curcumin in cancer cells was also achieved by conjugating hyaluronic acid (HA) on the surface of MSN. HA showed its targeting ability through the binding with CD-44 receptors in cancer cells. The synthesis of MSN-HA-C was verified by used several characterization techniques like TEM, SEM, XRD and DLS. MSN-HA-C showed diameter of ∼ 75 nm with negatively charged surface and drug loading content of 14.76 %. The synthesized nanohybrid showed MDA-MB-231 cell death by the induction of ROS, cell cycle arrest and modulation of NF-κB and Bax mediated apoptotic pathway. The nanohybrid also effectually decreased tumor volume in tumor-bearing mice compared with free C due to the increased bioavailability and higher cellular uptake of C in tumor tissue. Overall, the study offered that MSN-HA-C has increased anticancer efficacy than that of free curcumin.

Biodegradable nanocarriers based on chitosan-modified mesoporous silica nanoparticles for delivery of methotrexate for application in breast cancer treatment

Nanocarriers have demonstrated great promise in the delivery of hydrophobic drugs particularly to tumor spaces by enhanced permeability and retention (EPR) effects. Mesoporous silica nanoparticles (MSNs) are the attractive nanocarrier system to reduce the drug's toxic side effects, enable controlled drug release, prevent drug degradation and provide a biocompatible and biodegradable high surface area carrier. Surface-modified MSNs have been applied to increase drug loading and efficiency. In this study, functionalized MSNs loaded with methotrexate (MTX) were designed for use as a cytotoxic agent. The MSNs were first modified with 3-triethoxysilylpropylamine (APTES) and then with chitosan through covalent coupling mediated by glutaraldehyde. The physicochemical properties of the nanoparticles were optimized for each step. The loading percentage (12.2%) and release profile of MTX as an anti-breast cancer drug, loaded at amine-modified MSNs, were measured via high performance liquid chromatography (HPLC). Moreover, the uptake profiles of fluorescein isothiocyanate (FITC)-labeled MSN-APTES-chitosan with or without MTX were monitored on MCF7 cancer cells via confocal microscopy. Following exposure of nanoparticles to body fluids, they were surrounded by specific proteins that may affect their cellular uptake. Hence, the adsorption profiles of protein corona on the surface of MSN, amine-modified MSN and MTX-loaded MSN-APTES-chitosan were analyzed. The cytotoxic potential for killing breast cancer cells was also studied. The MTX loaded MSN-APTES-chitosan showed a positive effect at a low dose (0.5 μM MTX). In this study, we introduce a new method to synthesize biodegradable MSNs with small and uniform particle size, achieve high MTX loading via covalent amine and chitosan-functionalization, monitor the cellular uptake and demonstrate the potential to decrease the viability of breast cancer cells at low dose.

PH-Responsive porphyrin-silica nanoparticles conjugate via ionic self-assembly

Ionic self-assembly (ISA) is a powerful tool that has been exploited to create various functional nanomaterials through the electrostatic interactions of different building blocks. Herein, we disclose for the first time the synthesis and characterization of benzoic acid functionalized silica nanoparticles (MSNs-Bn) and its subsequent ISA with meso-tetrakis(N-methylpyridinium-4-yl)porphyrin (TMPyP) to form a pH responsive hybrid material. The resulting pH responsive conjugate is an attractive candidate as a drug delivery vehicle in which the MSNs-Bn act as a drug carrier and the TMPyP act as a capping agent for the silica nanopores. The application of these pH-responsive interactions between the negatively charged carboxylate groups on the surface of mesoporous silica nanoparticles and the positively charged porphyrin as a drug delivery system was investigated by studying the loading and release of Hoechst 33342 dye (a water-soluble biological stain with similar size to those of therapeutic drugs) in response to a pH change. The reported approach enables the delivery of a chemotherapeutic drug in addition to the TMPyP, which is also well-known as a photodynamic therapy (PDT) agent, thus paving the way for synergistic chemo-photodynamic cancer therapy. The study shows that the resulting conjugate demonstrate the drug delivery mechanism which is responsive to changing the pH values from 7.5 to 4.5, and can deliver about 2 wt% of the chemotherapeutic drug tested.

An optimized mesoporous silica nanosphere-based carrier system with chemically removable Au nanoparticle caps for redox-stimulated and targeted drug delivery

To date, numerous drug delivery systems based on mesoporous silica nanoparticles (MSNs) have been explored, but little has been done on optimizing the structure and composition of MSNs to achieve effective drug delivery for cancer cells. Ideal mesoporous drug carriers should incorporate drugs in a way that prevents pre-release in biological surroundings before reaching the targeted area, which usually requires the capping of the open ends on the surface and the incorporation of targeting ligands on the exterior of nanocarriers. In this study, an MSN-based drug carrier system was synthesized with biocompatible Au nanoparticles (NPs) as the ‘hard caps’, and folic acid conjugated to the surface for targeting folate receptor-overexpressed cancer cells. Disulfide bonds linking Au and MSN NPs were introduced to the MSN surface as the redox-sensitive and chemically removable components. To study the effect of structures of MSNs in drug release, three types of MSNs were compared, including hollow mesoporous silica NPs, large-pore hollow mesoporous silica NPs and typical nano-sized pores on the surface (MSN). To achieve optimal coverage of thiol groups, two methods of functionalization were compared in effecting drug loading and release in vitro. Finally, the effect of residual surfactant was also discussed in anticancer studies. Therefore, the appropriate MSN nanostructure for redox-sensitive and targeted drug delivery was optimized.