P(VPBA-DMAEA) as a pH-sensitive nanovalve for mesoporous silica nanoparticles based controlled release

A pH-sensitive controlled release system was proposed in this work, which consists of mesoporous silica nanoparticles(MSNs) functionalized on the pore outlets with poly(4-vinylphenybronic acid-co-2-(dimethylamino)ethyl acrylate) [P(VPBA-DMAEA)]. Four kinds of P(VPBA-DMAEA)-gated MSNs were synthesized and applied for the p H-sensitive controlled release. The results showed that P(VPBADMAEA) can work as a p H-sensitive nanovalve. The release behavior of the hybrid nanoparticles could be adjusted by changing the mole ratio of VPBA and DMAEA. With the increasing of the mole ratio of VPBA,the leakage of the entrapped molecules in the pores of MSNs could be decreased at neutral and alkaline conditions. By altering the p H of buffer from 4.0 to 8.0, the valve could be switched ‘‘on' and ‘‘off'reversibly. In addition, cells viability results indicated that these P(VPBA-DMAEA)-gated MSNs had good biocompatibility. We believe that these MSNs based p H-sensitive controlled release system will provide a promising nanodevice for sited release of drug delivery.     

Controlled drug release from bifunctionalized mesoporous silica

Serial of trimethylsilyl-carboxyl bifunctionalized SBA-15 (TMS/COOH/SBA-15) have been studied as carriers for controlled release of drug famotidine (Famo). To load Famo with large capacity, SBA-15 with high content of carboxyl groups was successfully synthesized by one-pot synthesis under the assistance of KCl. The mesostructure of carboxyl functionalized SBA-15 (COOH/SBA-15) could still be kept even though the content of carboxyl groups was up to 57.2%. Increasing carboxyl content could effectively enhance the loading capacity of Famo. Compared with pure SBA-15, into which Famo could be hardly adsorbed, the largest drug loading capacity of COOH/SBA-15 could achieve 396.9 mg/g. The release of Famo from mesoporous silica was studied in simulated intestine fluid (SIF, pH=7.4). For COOH/SBA-15, the release rate of Famo decreased with narrowing pore size. After grafting TMS groups on the surface of COOH/SBA-15 with hexamethyldisilazane, the release of Famo was greatly delayed with the increasing content of TMS groups.     

Sequestration of CO2 using Cu nanoparticles supported on spherical and rod-shape mesoporous silica

The CO₂ sequestration is one of the most promising solutions to tackle global warming. In this study, spherical mesoporous silica particles (MPS-S) and rod-shaped mesoporous silica particles (MPS-R) loaded with Cu nanoparticles were selectively prepared and employed for CO₂ adsorption. For the first time uniform Cu nanoparticles were incorporated into the rod-shaped mesoporous silica particles by post-synthesis modification using both N-[3-(trimethoxysilyl)propyl]ethylenediamine (PEDA) and ethylenediamine (EDA) as coupling agents. The physiochemical properties of the mesoporous and copper grifted silica composites were investigated by CHN elemental analysis, FTIR spectroscopy, thermogravimetric analysis, X-ray diffraction, energy dispersive X-ray spectroscopy (EDX), surface area analysis, scanning, transmission electron microscopy and gas analysis system (GSD 320, TERMO). The mesoporous silica shows highly ordered mesoporous structures, with the rod-shaped particles having a higher surface area than the spherical ones. Copper nanoparticles with an average diameter of 6.0 nm were uniformly incorporated into the MPS-S and MPS-R. Moreover, Cu-loaded mesoporous silica exhibits up to 40% higher CO₂ adsorption capacity than the bare MPS. The MPS-R modified with Cu nanoparticles showed a maximum CO₂ adsorption capacity of 0.62 mmol/g and the humidity showed a slight negative effect on CO₂ uptake process. The enhancement of CO₂ adsorption onto transition metal/mesoporous substrates provides basis for imminent CO₂ sequestration.     

Functionalized mesoporous materials for adsorption and release of different drug molecules: A comparative study

The adsorption capacity and release properties of mesoporous materials for drug molecules can be improved by functionalizing their surfaces with judiciously chosen organic groups. Functionalized ordered mesoporous materials containing various types of organic groups via a co-condensation synthetic method from 15% organosilane and by post-grafting organosilanes onto a pre-made mesoporous silica were synthesized. Comparative studies of their adsorption and release properties for various model drug molecules were then conducted. Functional groups including 3-aminopropyl, 3-mercaptopropyl, vinyl, and secondary amine groups were used to functionalize the mesoporous materials while rhodamine 6G and ibuprofen were utilized to investigate the materials’ relative adsorption and release properties. The self-assembly of the mesoporous materials was carried out in the presence of cetyltrimethylammonium bromide (CTAB) surfactant, which produced MCM-41 type materials with pore diameters of ∼2.7-3.3 nm and moderate to high surface areas up to ∼1000 m²/g. The different functional groups introduced into the materials dictated their adsorption capacity and release properties. While mercaptopropyl and vinyl functionalized samples showed high adsorption capacity for rhodamine 6G, amine functionalized samples exhibited higher adsorption capacity for ibuprofen. While the diffusional release of ibuprofen was fitted on the Fickian diffusion model, the release of rhodamine 6G followed Super Case-II transport model.     

Construction of a pH-responsive drug delivery platform based on the hybrid of mesoporous silica and chitosan

Mesoporous silica nanoparticles (MSN) have been widely used for drug delivery due to their large specific surface area and excellent biocompatibility. However, the mesoporous structure of MSN would lead to the inevitable “premature release” of the drugs, and therefore the modification of MSN for controlled delivery seems to be a necessary step. Herein, chitosan (CS) was used for the surface functionalization of MSN via amidation reaction, and the introduced CS could function as a “gatekeeper” and the drug of methotrexate (MTX) might be encapsulated in the mesopores of MSN. As a result, the “premature release” of the encapsulated MTX could be effectively circumvented with the aid of the CS cap. More importantly, the drug delivery from the hybrid of MSN and CS (MSN/CS) can be endowed with pH-sensitivity by the introduction of CS because the amide bonding between CS and MSN is highly pH-sensitive. The cumulative release of MTX from the MSN/CS is more pronounced at pH 5.0 (80.86%) than those at pH 6.8 (40.46%) and pH 7.4 (18.25%).     

Dual pH and glucose sensitive gel gated mesoporous silica nanoparticles for drug delivery

A low-molecular-weight gel with dual pH and glucose sensitivity was designed as the gate controller for mesoporous silica nanoparticles (MSNs) to fabricate a smart drug delivery system. The smart gel caped MSNs could control the antidiabetic drug release via the detection of glucose and pH levels.     

Temperature-sensitive polypeptide brushes-coated mesoporous silica nanoparticles for dual-responsive drug release

A biopolymer-inorganic hybrid system (MSN@PBLGF) is designed and fabricated from mesoporous silica nanoparticles (MSNs) and folic acid (FA)-terminated temperature-sensitive synthetic polypeptide, i.e., poly(γ-benzyl-l-glutamate) (PBLG) derivative, through a thiol-disulfide exchange reaction, where MSNs with high drug loading capacity serve as drug nanocarriers and the biocompatible PBLG biopolymer brushes installed on MSN surface through disulfide bonds endow the system with tumor-specific recognition ability and GSH/temperature dual-stimuli responsiveness. Controlled drug release experiments indicate that DOX can be tightly hosted in the system with limited premature release, but efficiently released in response to an increased concentration of GSH and/or an elevated temperature. Intracellular experiments demonstrate that the DOX-loaded MSN@PBLGF nanohybrid shows outstanding cellular uptake and cell-growth inhibition effects on human lung cancer cell line A549 in comparison with healthy human cells such as hepatocyte cells LO2.     

Synthesis of hierarchical sieve-like mesoporous silica nanoparticle aggregates via centrifugal method for drug delivery system

A facile approach towards the scaled-up synthesis of a novel hierarchical sieve-like structure of mesoporous silica nanoparticle aggregates (hsMSNA) with high drug encapsulation efficiency and sustained release behaviors acting as a drug delivery system in the field of nanomedicine.     

Temperature-sensitive polypeptide brushes-coated mesoporous silica nanoparticles for dual-responsive drug release

A multifunctional nanohybrid based on mesoporous silica nanoparticle and biocompatible polypeptide was fabricated for targeted and dual-responsive therapy of tumor cells.     

Facile one-pot synthesis of PEGylated monodisperse mesoporous silica nanoparticles with controllable particle sizes

In this work, we describe the one-pot synthesis of PEGylated mesoporous silica nanoparticles （MSNs） with uniform shape, tunable sizes, and narrow size distributions. The size of these nanoparticles can be controlled from 49 nm to 98 nm by simply varying the concentration oftriethanolamine during the base- catalyzed sol-gel reaction. Particles were characterized by transmission electron microscopy, dynamic light scattering, Fourier transform infrared spectrometry, thermogravimetric analysis, and nitrogen adsorption-desorption measurements. These PEGylated MSNs exhibited excellent long-term stability in biological media, which ensures their potential applications in drug delivery.     

A study of carboxylic-modified mesoporous silica in controlled delivery for drug famotidine

A series of pure silica MSU and carboxylic-modified MSU materials were prepared. The formation of mesoporous silica materials with terminal carboxylic groups on pore surface was performed by the acid-catalyzed hydrolysis of cyano to carboxylic. Then their potential applications in controlled drug delivery carriers were investigated. Drug famotidine was selected as a model molecule out of the consideration of the terminal amino groups in its molecule. The adsorption experiments show significant adsorption of famotidine on the carboxylic-modified MSU materials. And, the functionalization level of carboxylic groups has been found to be the key factor affecting the adsorption capacities of the modified MSU materials for famotidine. Subsequently, three kinds of release fluids, including simulated gastric medium, simulated intestinal medium, and simulated body fluid, were used to test the famotidine release rate from the carboxylic-modified MSU material. Obvious delayed effect has been observed for the famotidine release from the carboxylic-modified mesoporous silica material under the in vitro assays.     

含可脱除侧基的功能化微凝胶及其在药物释放中的应用

环境敏感微凝胶由于其对外界刺激的快速响应能力在药物传输和释放领域得到广泛的关注.本文报道了一种侧链含可脱除基团的温敏微凝胶,并探讨了其在药物释放中的潜在应用.通过分子设计,合成出含侧链N-叔丁氧羰基(N-Boc)的疏水单体N-(N-叔丁氧羰基-乙二胺)甘氨酸二肽甲基丙烯酰胺(BEMAGG),然后将其与N-异丙基丙烯酰胺(NIPAAm)沉淀共聚合直接得到侧链含Boc基团的微凝胶MG-Boc.通过浊点法、粒径和Zeta电位测定研究了微凝胶中Boc基团在酸中的脱除过程及其对微凝胶性能的影响,研究表明Boc基团的脱除显著影响微凝胶的体积相转变温度、粒径和Zeta电位.对盐酸阿霉素药物的释放研究表明,释放明显依赖于释放介质的pH值.该响应性的微凝胶在药物控制释放领域具有潜在的应用前景.     

Lipid,protein and poly(NIPAM) coated mesoporous silica nanoparticles for biomedical applications

In the past decade, mesoporous silica nanoparticles (MSNs) as nanocarriers have showed much potential in advanced nanomaterials due to their large surface area and pore volume. Especially, more and more MSNs based nanodevices have been designed as efficient drug delivery systems (DDSs) or biosensors. In this paper, lipid, protein and poly(NIPAM) coated MSNs are reviewed from the preparation, properties and their potential application. We also introduce the preparative methods including physical adsorption, covalent binding and self-assembly on the MSNs' surfaces. Furthermore, the interaction between the aimed cells and these molecular modified MSNs is discussed. We also demonstrate their typical applications, such as photodynamic therapy, bioimaging, controlled release and selective recognition in biomedical field.     

Synthesis of anionic gemini surfactant-templated mesoporous silica nanoparticles and its adsorption application for Pb2+

Abstract

Amino-functionalized mesoporous silica nanoparticles (AFMSN) were prepared based on the self-assembly process of the pre-fabricated template of anionic gemini surfactant. The perfect mass ration of the reactants for the synthesis of the AFMSN with high surface area and amino loading was optimized by orthogonal experiments. Adsorption capability of the optimized product for lead ion (Pb²⁺) was investigated in detail. Specially, the effects of the amino content, solution pH, adsorbent dosage, temperature, and interference of other metal ions on the removal efficiency of Pb²⁺ were studied. It is found that these factors can greatly affect the removal efficiency of Pb²⁺ and the prepared adsorbent exhibits the high adsorption selectivity for Pb²⁺. At an optimal condition, the AFMSN adsorbent presents an excellent adsorption capacity for Pb²⁺ up to 211.42?mg/g. The adsorption kinetics study revealed that the pseudo-second-order model could well describe the Pb²⁺ adsorption process, and the adsorption isotherm was fitted well with the Langmuir model. More importantly, the AFMSN adsorbent could be recycled 8 times and a high adsorption efficiency of Pb²⁺ could still be maintained. Therefore, the prepared AFMSN adsorbent may find practical application in removing Pb²⁺ from the polluted water.     

Characterization of gold nanoparticles electrochemically deposited on amine-functioned mesoporous silica films and electrocatalytic oxidation of glucose

This study reports the preparation and characterization of gold nanoparticles deposited on amine-functioned hexagonal mesoporous silica (NH₂–HSM) films and the electrocatalytic oxidation of glucose. Gold nanoparticles are fabricated by electrochemically reducing chloroauric acid on the surface of NH₂–HSM film, using potential step technology. The gold nanoparticles deposited have an average diameter of 80 nm and show high electroactivity. Prussian blue film can form easily on them while cycling the potential between −0.2 and 0.6 V (vs saturated calomel electrode) in single ferricyanide solution. The gold nanoparticles loading NH₂–HSM-film-coated glassy carbon electrode (Au–NH₂–HSM/GCE) shows strong catalysis to the oxidation of glucose, and according to the cathodic oxidation peak at about 0.16 V, the catalytic current is about 2.5 μA mM⁻¹. Under optimized conditions, the peak current of the cathodic oxidation peak is linear to the concentration of glucose in the range of 0.2 to 70 mM. The detection limit is estimated to be 0.1 mM. In addition, some electrochemical parameters about glucose oxidation are estimated.     

Facile assembly of mesoporous silica nanoparticles with hierarchical pore structure for CO2 capture

In the work, we propose an efficient one-pot approach for synthesis of a new type of mesoporous silica nanoparticles (MSNs). That can be successfully realized by using tetraethylorthosilicate (TEOS) and N-[3-(trimethoxysilyl)propyl]ethylenediamine (TSD) as the silica precursors and cetyltrimethylammonium bromide (CTAB) as the structure-directing agent through a facile assembly process. The as-synthesized MSNs possess a spherical morphology with about 230 nm, a relatively high surface area of 133 m²/g, and a hierarchical pore size distribution. When applied as the sorbents, the amine-functioned MSNs demonstrate the enhanced adsorption capacity for CO₂ capture (at 1 bar, 15 vol% CO₂, up to 80.5 mg/g at 75 °C), high selectivity, and good cycling durability, benefiting from the suitable modification of polyethyleneimine.     

Facile assembly of mesoporous silica nanoparticles with hierarchical pore structure for CO2 capture

A facile one-pot hydrothermal approach has been developed for the preparation of mesoporous silica nanoparticles (MSNs) with hierarchical pore structure. The PEI-modified MSNs exhibit an improved adsorption capacity for CO₂ capture.     

A tri-responsive dual-drug delivery system based on mesoporous silica nanoparticles@polydopamine@graphene oxide nanosheets for chemo-photothermal therapy of osteosarcoma

A pH, redox and near infrared (NIR) irradiation tri-responsive dual-drug delivery system (DDDS) is constructed for the treatment of osteosarcoma. Methotrexate (MTX) is encapsulated into the mesoporous silica nanoparticles (MSNs) by polydopamine (PDA), and then the core–shell structured MTX/MSNs@PDA is embedded into the graphene oxide (GO) nanosheets to further enhance the photothermal conversion capability of this system. The resultant MTX/MSNs@PDA@GO is co-encapsulated with naringin (Nar) into the hydrogels of carboxymethyl cellulose (CMC) and cystamine (Cys) generated through amidation reaction. The disulfide linkage (–S–S–) in Cys can be reduced to sulphydryl groups (–SH) by glutathione (GSH), resulting in the degradation of the hydrogels; on the other hand, both PDA and the amide linkage between CMC and Cys are pH-sensitive. Therefore, the constructed DDDS can be used for pH-, redox- and NIR irradiation-responsive delivery of MTX and Nar. Finally, the validity of the developed DDDS is evaluated by cytotoxicity test.     

Functionalized ionic liquid modified mesoporous silica SBA-15: a novel, designable and efficient carrier for porcine pancreas lipase

A series of functionalized ionic liquid modified mesoporous silicas SBA-15 (FIL-SBA) were synthesized by modulating the loading and cation/anion ratio of the functionalized ionic liquid (FIL). The prepared materials FIL-SBA were used as a novel carrier system to immobilize porcine pancreas lipase (PPL). Enzymatic activity and reusability of the immobilized enzyme were investigated using the triacetin hydrolysis reaction. The combined advantages of the nano-sized pore diameter, large surface area and high pore volume of SBA-15, and the tunable properties of the FIL for enzymes immobilized in FIL-SBA gave a maximum improvement of 570% in relative activity, with 63% retention of initial activity after five cycles of use. Carriers and immobilized enzymes were characterized using nitrogen adsorption, small-angle X-ray diffraction (SXRD), Fourier transform infrared (FT-IR), elemental analysis, nuclear magnetic resonance (NMR), scanning and transmission electron microscopy (SEM and TEM). It was shown that the introduction of FIL influenced the catalytic behavior of PPL significantly by changing the structure and surface properties of the carriers.