Spherical Mesoporous Silica Nanoparticles Research Articles

Shape and Shear Stress Impact on the Toxicity of Mesoporous Silica Nanoparticles: In Vitro and In Vivo Evidence.

Mesoporous silica nanoparticles (MSNs) are widely used in the biomedical field because of their unique and excellent properties. However, the potential toxicity of different shaped MSNs via injection has not been fully studied. This study aims to systematically explore the impact of shape and shear stress on the toxicity of MSNs after injection. An in vitro blood flow model was developed to investigate the cytotoxicity and the underlying mechanisms of spherical MSNs (S-MSN) and rodlike MSNs (R-MSN) in human umbilical vein endothelial cells (HUVECs). The results suggested that the interactions between MSNs and HUVECs under the physiological flow conditions were significantly different from that under static conditions. Whether under static or flow conditions, R-MSN showed better cellular uptake and less oxidative damage than S-MSN. The main mechanism of cytotoxicity induced by R-MSN was due to shear stress-dependent mechanical damage of the cell membrane, while the toxicity of S-MSN was attributed to mechanical damage and oxidative damage. The addition of fetal bovine serum (FBS) alleviated the toxicity of S-MSN by reducing cellular uptake and oxidative stress under static and flow conditions. Moreover, the in vivo results showed that both S-MSN and R-MSN caused cardiovascular toxicity in zebrafish and mouse models due to the high shear stress, especially in the heart. S-MSN led to severe oxidative damage at the accumulation site, such as liver, spleen, and lung in mice, while R-MSN did not cause significant oxidative stress. The results of in vitro blood flow and in vivo models indicated that particle shape and shear stress are crucial to the biosafety of MSNs, providing new evidence for the toxicity mechanisms of the injected MSNs.

Biomimetic virus-like mesoporous silica nanoparticles improved cellular internalization for co-delivery of antigen and agonist to enhance Tumor immunotherapy

Nanocarrier antigen-drug delivery system interacts specifically with immune cells and provides intelligent delivery modes to improve antigen delivery efficiency and facilitate immune progression. However, these nanoparticles often have weak adhesion to cells, followed by insufficient cell absorption, leading to a failed immune response. Inspired by the structure and function of viruses, virus-like mesoporous silica nanoparticles (VMSNs) were prepared by simulating the surface structure, centripetal-radialized spike structure and rough surface topology of the virus and co-acted with the toll-like receptor 7/8 agonist imiquimod (IMQ) and antigens oocyte albumin (OVA). Compared to the conventional spherical mesoporous silica nanoparticles (MSNs), VMSNs which was proven to be biocompatible in both cellular and in vivo level, had higher cell invasion ability and unique endocytosis pathway that was released from lysosomes and promoted antigen cross-expression. Furthermore, VMSNs effectively inhibited B16-OVA tumor growth by activating DCs maturation and increasing the proportion of CD8+ T cells. This work demonstrated that virus-like mesoporous silica nanoparticles co-supply OVA and IMQ, could induce potent tumor immune responses and inhibit tumor growth as a consequence of the surface spike structure induces a robust cellular immune response, and undoubtedly provided a good basis for further optimizing the nanovaccine delivery system.

"Hook&Loop" multivalent interactions based on disk-shaped nanoparticles strengthen active targeting.

How to enhance active targeting efficiency remains a challenge. Multivalent interactions play a crucial role in improving the binding ability between ligands and receptors. It is hypothesized that nanoparticles bearing a flat conformation attain simultaneous formation of multiple ligand-receptor bindings, which could be vividly metaphorized by the "Hook&Loop" rationale. In this study, spherical, rod-shaped and disk-shaped folic acid-modified red blood cell membrane-coated biomimetic mesoporous silica nanoparticles (FRMSNs) were prepared to verify the shape-based multivalent interactions. The fundamental concepts of multivalent interactions have been proved by a series of both in vitro and in vivo evaluations. Physical characterization confirmed the morphology, shape and surface features of FRMSNs. Strengthened binding and internalization of disk-shaped FRMSNs by K562 cells stresses the merits of multivalent interactions. Whereas Bio-TEM visually demonstrates the proposed "plane" contact of disk-shaped particles with cells, quantification further confirmed strengthened "plane" binding affinity with folate binding proteins owing to multivalent interactions. In K562 xenograft mice, doxorubicin-loaded disk-shaped FRMSNs effectively slowed down chronic myeloid leukemia progression. It is concluded that disks favor multivalent interactions which leads to enhanced active targeting efficiency.

Pickering Emulsions Stabilized by Mesoporous Nanoparticles with Different Morphologies in Combination with DTAB.

The morphology of nanoparticles plays a significant role in the properties and applications of Pickering emulsions. Oil-in-water (O/W) Pickering emulsions were prepared using spherical, rod-like, and thread-like mesoporous silica nanoparticles (MSNPs) in combination with the cationic surfactant dodecyltrimethylammonium bromide (DTAB) as a stabilizer. The effects of nanoparticle morphology on the stability and stimuli-responsive properties of Pickering emulsions were investigated. For spherical and rod-like MSNP systems, stable Pickering emulsions were obtained at DTAB concentrations above 0.2 mmol·L–1. Stable Pickering emulsions containing thread-like MSNPs were produced at lower DTAB concentrations of approximately 0.1 mmol·L–1. The droplets with thread-like MSNPs were extremely large with an average diameter around 700 μm at DTAB concentrations of 0.1–0.3 mmol·L–1, which were approximately 20 times larger than those of conventional droplets. Scanning electron microscopy (SEM) images showed that all three types of MSNPs were located at the O/W interfaces. Irrespective of the morphology of the MSNPs, all the stable Pickering emulsions retained their original appearance for more than 6 months. By adding NaOH and HCl alternatively, the Pickering emulsions containing spherical and rod-like MSNPs could be switched between unstable and stable states more than 60 times. The Pickering emulsions containing thread-like MSNPs, by contrast, could have their droplet size switched between large and small more than 10 times without any obvious phase separation. The high anisotropy of thread-like MSNPs contributed to the low interface curvature of the droplets. This study revealed the relationship between the morphology of MSNPs and the characteristics of Pickering emulsions. These results enrich our knowledge about the formulation of Pickering emulsions and expand their applications.

Spherical and rod shaped mesoporous silica nanoparticles for cancer-targeted and photosensitizer delivery in photodynamic therapy

Mesoporous silica nanoparticles (MSNPs) have attracted much attention in many biomedical applications. One of the fields in which smart functional nanosystems have found wide application is cancer treatment. Here, we present new silica nanoparticle-based systems which have been explored as efficient vehicles to transport and deliver photosensitizers (PSs) into tumor tissues during photodynamic therapy (PDT). In this work, we report the preparation, characterization, and in vitro studies of distinct shaped MSNPs grafted with S-glycoside porphyrins (Pors). The ensuing nanomaterials were fully characterized, and their properties as third-generation PSs for PDT against two bladder cancer cell lines, HT-1376 and UM-UC-3, were examined. The best uptake results were obtained for MSNP-PS2, while MSNP-PS1 showed the lowest cellular uptake among the nanocarriers tested, but revealed the best phototoxicity in both cancer cells. Overall, the phototoxicity was higher with MSNPs than with mesoporous silica nanorods (MSNRs) and higher uptake and phototoxicity were consistently observed in UM-UC-3 rather than in HT-1376 cancer cells.

Fluorescent spherical mesoporous silica nanoparticles loaded with emodin: Synthesis, cellular uptake and anticancer activity

The natural product emodin (EO) exhibits anti-inflammatory, antiangiogenesis and antineoplastic properties in vitro and in vivo. Due to its biological properties as well as its fluorescence, EO can be useful in pharmacology and pharmacokinetics. To enhance its selectivity to cancer cells, EO was loaded into non-fluorescent and novel fluorescent spherical mesoporous nanoparticles bearing N-methyl isatoic anhydride (SNM~M) or lissamine rhodamine B sulfonyl moieties (SNM~L). The propylamine functionalized mesoporous silica nanomaterial (SNM) were characterized by powder X-ray diffraction (XRD), nitrogen gas sorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), fluorescence spectroscopy, thermogravimetric analysis (TGA) and UV spectroscopy. The cytotoxicity of EO-loaded nanoparticles was tested against the human colon carcinoma cell line HT-29. Non-loaded SNM did not affect cell proliferation, whereas those loaded with EO were at least as efficient as EO alone. It could be shown by fluorescence microscopy that the uptake of silica nanomaterial by the tumor cells occurred within 2 h and the release of EO occurred within 48 h of treatment. Flow cytometry and Western blot analysis showed that SNM containing EO induced apoptosis in HT-29 cells.

Facile approach for the synthesis of spherical mesoporous silica nanoparticles from sodium silicate

We developed a facile synthetic method for the preparation of spherical mesoporous silica nanoparticles from a sodium silicate solution. Spherical mesoporous silica with an overall size of several hundreds of nanometers was obtained through a simple sol–gel process using acetic acid and polyethylene glycol (PEG) as a pH adjuster and morphology directing agent, respectively. In this method, PEG is an essential component that affects the shape of silica particles and that leads to the formation of mesopores on silica. Additionally, the size of the mesopores could be easily controlled by changing the reaction temperature. Thus, we successfully synthesized spherical silica nanoparticles with tunable mesopores ranging from 3 to 40 nm. This synthetic method can be valuable in developing customized porous silica nanoparticles using an inexpensive silica resource.

Sacrificial sulphonated polystyrene template-assisted synthesis of mesoporous hollow core-shell silica nanoparticles for drug-delivery application

Spherical mesoporous hollow core-shell silica nanoparticles (HCSNs) of size 200 ± 50 nm with tunable thickness from 20 to 60 nm are synthesized using a sacrificial sulphonated polystyrene (PS, particle size 160 nm) template. A facile method is adopted for the sulphonation of PS using sulphuric acid, which enhanced the negative charge on the surface of PS as confirmed by zeta potential analysis and Fourier transform infrared radiation analysis. The thickness of the silica shell is tuned by altering the concentration of the silica precursor and is found to increase due to the use of the sulphonated PS template. N2 adsorption/desorption studies reported the variation of specific surface area of HCSNs from 644.1 to 197.8 m2 g−1 and average pore size from 1.55 to 3.4 nm. The drug release behaviour of HCSNs with different shell thicknesses is investigated using doxorubicin as the model drug. A delay in the drug release for ~300 min is successfully achieved by employing HCSNs with enhanced thickness of 60 nm. Application of HCSNs in targeted drug delivery was further supported by the in-vitro cytotoxicity studies carried out on lung adenocarcinoma cells.

Interaction of lignin-derived dimer and eugenol-functionalized silica nanoparticles with supported lipid bilayers

The potential to impart surfaces with specific lignin-like properties (i.e. resistance to microbes) remains relatively unexplored due to the lack of well-defined lignin-derived small molecules and corresponding surface functionalization strategies. Here, allyl-modified guaiacyl β-O-4 eugenol (G-eug) lignin-derived dimer is synthesized and attached to mesoporous silica nanoparticles (MSNPs) via click chemistry. The ability of G-eug lignin-dimer functionalized particles to interact with and disrupt synthetic lipid bilayers is compared to that of eugenol, a known natural antimicrobial. Spherical MSNPs (∼150 nm diameter with 4.5 nm pores) were synthesized using surfactant templating. Post-synthesis thiol (SH) attachment was performed using (3-mercaptopropyl) trimethoxysilane and quantified by Ellman’s test. The resultant SH-MSNPs were conjugated with the G-eug dimers or eugenol by a thiol-ene reaction under ultraviolet light in the presence of a photo initiator. From thermogravimetric analysis (TGA), attachment densities of approximately 0.22 mmol eugenol/g particle and 0.13 mmol G-eug dimer/g particle were achieved. The interaction of the functionalized MSNPs with a phospholipid bilayers of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (representing model cell membranes) supported on gold surface was measured using Quartz Crystal Microbalance with Dissipation monitoring (QCM-D). Eugenol-grafted MSNPs in PBS (up to 1 mg/mL) associated with the bilayer and increased the mass adsorbed on the QCM-D sensor. In contrast, MSNPs functionalized with G-eug dimer show qualitatively different behavior, with more uptake and evidence of bilayer disruption at and above a particle concentration of 0.5 mg/mL. These results suggest that bio-inspired materials with conjugated lignin-derived small molecules can serve as a platform for novel antimicrobial coatings and therapeutic carriers.

Time- and dose-dependent gene expression analysis of macrophage response as a function of porosity of silica nanoparticles

There is a limited amount of information available on gene expression regulation of macrophages in response to changing the time of exposure, concentration, and physicochemical properties of nanomaterials. In this study, RAW264.7 macrophages were treated with spherical nonporous and mesoporous silica nanoparticles of similar size at different incubation times and concentrations. RNA-sequencing was used to study transcriptional profiles. Bioinformatics analyses, functional annotation clustering, and network analyses were employed to understand signaling pathways of cellular response as a function of porosity, incubation time, and concentration. Porosity introduced drastic changes to the genomic response of macrophages at equitoxic concentrations and incubation times. Direct relations between increases in time and concentration with an increased number of differentially expressed genes were observed.

Inducing Macrophages M2 Polarization by Dexamethasone Laden Mesoporous Silica Nanoparticles from Titanium Implant Surface for Enhanced Osteogenesis

The study conveys an idea to enhance the osseointegration of titanium implant (Ti) through modulating macrophages M2 polarization. The ~ 100 nm spherical mesoporous silica nanoparticles (MSN) that compromised of ~ 4-nm-diameter nano-tunnels were synthesized by the conventional “sol–gel” method, into which the dexamethasone (DEX) was loaded (DEX@MSN). The DEX@MSN could consistently release DEX and showed favorable cytocompatibility in RAW264.7 cells. The arginase-1 expression, a specific marker for macrophages M2 polarization, was also enhanced by DEX@MSN treatment. Then, the Ti was pre-treated with anodization under 5 V to generate the titania nanotubes with ~ 30 nm diameter (NT-30) and the DEX@MSN was introduced onto NT-30 surface via electrophoretic deposition, with the aid of chitosan. After optimizing the deposition parameters, the supernatants of RAW264.7 from the decorated implant surface could significantly promote the osteogenic differentiation of murine primary bone marrow mesenchymal stem cells. These findings demonstrate that delivery of DEX from implant surface can modulate the macrophages M2 polarization and result in favorable osteogenesis.

Preparation and drug release application of pH and light dual-stimuli-responsive nanocarrier based on mesoporous silica nanoparticles

The spherical mesoporous silica nanoparticles (MSNs) with good dispersity and uniform pore structure were prepared and functionalized by amino and 2-bromoisobutyrate successively. The random copolymer brushes of 1′-(2-acryloxyethyl)-3′,3′-dimethyl-6-nitrospiro-(2H-1-benzopyran-2,2′-indoline) (SPMA) and methacrylic acid (MAA) on the surface of MSNs were obtained via chemical hydrolysis of the precursor random copolymer MSNs-g-P(SPMA-co-tert-butyl methacrylate (tBMA)) in acidic conditions. The pH or light stimuli-responsive behavior and the dual-responsive process were recorded by UV-Vis absorption spectroscopy and dynamic light scattering (DLS). Furthermore, doxorubicin (DOX) as model drug molecule was loaded into the polymer brushes (as the nanocarrier), and the controlled release processes of DOX under the external stimulations were studied to some extent.

Synthesis of ultra small nanoparticles (< 50 nm) of mesoporous MCM-48 for bio-adsorption

Mono-dispersed spherical MCM-48 mesoporous silica nanoparticles (MSN) with cubic Ia3d mesostructure were synthesized under different stirring conditions using hexadecyltrimethyl ammonium bromide as structure directing agent and EO20PO70EO20 copolymer as particle size control. Results indicated that the EO20PO70EO20 works well in the reduction of nanoparticle size. In addition, increasing the stirring rate transformed mesoporosity from 2-D hexagonal P6mm to 3-D cubic Ia3d. The biomolecule adsorption properties of prepared ultra small nanoparticles of MCM-48 were compared with that of MCM-48 with ten times larger particle sizes. MCM-48 with smaller particle sizes adsorbed much more vitamin B12 compared with MCM-48 with larger particles. In addition, diffusion of vitamin in the intraparticle spaces occurred only for MCM-48 with ultra-small nanoparticles.

Novel SO3H functionalized magnetic nanoporous silica/polymer nanocomposite as a carrier in a dual-drug delivery system for anticancer therapy

Magnetic nanoporous silica particles (MNS) with spherical morphology and 100 nm particle with advanced characteristics suitable for nanomedicine purposes were synthesized. The obtained nanoparticles were modified with SO3H groups in a two-step post synthesis procedure. An anticancer drug, mitoxantrone (MTX), and an anti-inflammatory drug, prednisolone (PRD), were loaded on the silica support. The mitoxantrone loaded MNS-SO3H nanoparticles were coated by chitosan and then prednisolone was infused in the chitosan layer. A second layer of alginate was then applied around the prednisolone and mitoxantrone containing formulation. All materials were characterized by XRD, N2 physisorption, Mössbauer spectroscopy, magnetization measurements and transmission electron microscopy in order to demonstrate that by the applied preparation method around 11 nm sized maghemite crystals embedded in spherical mesoporous silica nanoparticles were obtained with high pore volume and surface area. Thermal gravimetric analysis, ATR FT-IR spectroscopy and in vitro release experiments proved that MTX and PRD were successfully loaded on the silica matrix. Alginate coating further improved the release properties by preventing the burst release of MTX and PRD. The cytotoxicity properties of the drugs loaded formulations and their ability to retain the intrinsic pharmacological properties of the encapsulated drugs were investigated on a panel of human tumor cell lines.

A study of some fundamental physicochemical variables on the morphology of mesoporous silica nanoparticles MCM-41 type

All variables affecting the morphology of mesoporous silica nanoparticles (MSN) should be carefully analyzed in order to truly tailored design their mesoporous structure according to their final use. Although complete control on MCM-41 synthesis has been already claimed, reproducibility and repeatability of results remain a big issue due to the lack of information reported in literature. Stirring rate, reaction volume, and system configuration (i.e., opened or closed reactor) are three variables that are usually omitted, making the comparison of product characteristics difficult. Specifically, the rate of solvent evaporation is seldom disclosed, and its influence has not been previously analyzed. These variables were systematically studied in this work, and they were proven to have a fundamental impact on final particle morphology. Hence, a high degree of circularity (C = 0.97) and monodispersed particle size distributions were only achieved when a stirring speed of 500 rpm and a reaction scale of 500 mL were used in a partially opened system, for a 2 h reaction at 80 °C. Well-shaped spherical mesoporous silica nanoparticles with a diameter of 95 nm, a pore size of 2.8 nm, and a total surface area of 954 m2 g−1 were obtained. Final characteristics made this product suitable to be used in biomedicine and nanopharmaceutics, especially for the design of drug delivery systems.

Tuning particle morphology of mesoporous silica nanoparticles for adsorption of dyes from aqueous solution

Spherical and rod mesoporous silica nanoparticles with hexagonal mesostructure were prepared using the modified Stöber method. The morphology, size and internal pore structure can be controlled by simple changing of surfactant concentration and water:ethanol molar ratio. Monodispersed spheroid MCM-41 was obtained at 40°C under basic conditions using cetyltrimethylammonium bromide (C16TAB) as template. Obtained materials were characterized by X-ray diffraction (XRD), nitrogen physisorption (BET), transmission electron microscopy (TEM) and scanning electronic microscopy (SEM). The results reveal that the pore volume and surface area increase when the amount of C16TAB increases whereas the pore diameter and particle size decrease. However, the use of ethanol as cosolvent led to an increase in the particles’ size. Moreover, the addition of a 3-aminopropyltriethoxysilane greatly influenced the final particle shape. The material was effectively used for the removal of two fluorescent dyes (Hoechst 33342 and rhodamine 6g) from aqueous solution. Adsorption isotherm models, Langmuir, Freundlich and Temkin were used to simulate the equilibrium data. The Langmuir model was found to fit the experimental data better than others models.

Synthesis of Spherical Carbon Nitride-Based Polymer Composites by Continuous Aerosol-Photopolymerization with Efficient Light Harvesting.

Here we report a novel, facile, and sustainable approach for the preparation of spherical submicrometer carbon nitride-based polymer composites by a continuous aerosol-photopolymerization process. In this regard, spherical mesoporous carbon nitride (SMCN) nanoparticles were initially prepared via a nanocasting approach using spray-drying synthesized spherical mesoporous silica (SMS) nanoparticles as hard templates. In addition to experimental characterization, the effect of porosity on the light absorption enhancement and consequently the generation rate of electron-hole pairs inside the SMCN was simulated using a three-dimensional finite difference time-domain (FDTD) method. To produce the carbon nitride-based polymer composite, SMCN nanoparticles exhibit excellent performance in photopolymerization of butyl acrylate (PBuA) monomer in the presence of n-methyldiethanolamine (MDEA) as a co-initiator in a continuous aerosol-based process. In this one-pot synthesis, SMCN nanoparticles act not only as photoinitiators but at the same time as fillers and templates. The average aerosol residence time in the photoreactor is about 90 s. The presented aerosol-photopolymerization process avoids the need for solvent and surfactant, operates at room temperature, and, more importantly, is suitable to produce the spherical composite with hydrophobic polymers. Furthermore, we simulated the condition of SMCN nanoparticles during illumination in the gas phase process, which can freely rotate. The results demonstrated that the hole (h(+)) density is almost equally distributed in the whole part of the SMCN nanoparticles due to their rotation, leading to efficient light harvesting and more homogeneous photoreaction. The combination of the outstanding features of environmentally friendly SMCN, photopolymerization, and aerosol processing might open new avenues, especially in green chemistry, to produce novel polymer composites with multifunctional properties.

Protein Adsorption From Biofluids on Silica Nanoparticles: Corona Analysis as a Function of Particle Diameter and Porosity.

A study on the adsorption of proteins from fetal bovine serum (FBS) on spherical dense and mesoporous silica nanoparticles with a wide range of diameters, from 70 to 900 nm, is presented. Monodisperse populations of particles with a range of diameters were obtained through modifications of the Stöber method. Extensive characterization of the particles was then performed using N2 physisorption, TEM, DLS, and ζ-potential. Following serum exposure, proteomic evaluation in concert with thermogravimetric analysis revealed the associated concentrations of each protein identified in the hard corona. Small particles adsorbed the largest amount of protein, due to their larger external surface area. Proteins with low molecular weights (<50 kDa) constituted the majority of the protein corona, totaling between 60 and 80% of the total mass of adsorbed protein. Here, the higher surface curvature of small particles favors the enrichment of smaller proteins. Porosity does not promote protein adsorption but improves deposition of the low molecular weight protein fraction due to the size-exclusion effect related to pore diameter. These results have important implications for the use of dense and porous silica nanoparticles in biomedical applications.

Monitoring the Hemolytic Effect of Mesoporous Silica Nanoparticles after Human Blood Protein Corona Formation

AbstractThe interaction of promising nanoparticles with red blood cells (RBCs) is a critical point to be addressed in nanomedicine and nanotoxicology, and the hemolytic assay is a classical and common test used to evaluate such interactions and the consequent nanoparticle toxicity. In addition, the protein corona is an emergent concept in bionanoscience associated with the manifestation of energetically driven protein–nanoparticle interactions, with a great impact on the nanomaterial toxicity assessment. In the convergence of these two concepts, we evaluated the influence of the formation of the protein corona during the hemolysis induced by spherical mesoporous silica nanoparticles with silanol groups on the external surface (MSN‐SiOH), which present a confirmed toxicity on RBCs when they are dispersed as a colloid in phosphate buffer saline solution (PBS). It was observed that human blood proteins such as human serum albumin (HSA), human plasma (HP), hemoglobin (Hb), and RBC lysate, termed hemolysate (HL), can suppress the hemolytic effect induced by MSN‐SiOH in a dose‐dependent manner. The EC50 values of hemolysis suppression were 24, 8.0, 19, and 28 μg mL–1 for HSA, HP, Hb, and HL, respectively. This work thus shows that the results of the hemolytic assay that defines the toxicity and bioreactivity of silica nanoparticles (and others) must be interpreted as a function of the formation of the protein corona.

Spherical mesoporous silica nanoparticles/tailor-made polystyrene nanocomposites by in situ reverse atom transfer radical polymerization

Spherical mesoporous silica nanoparticles (MCM-41)/tailor-made polystyrene nanocomposites were synthesized by in situ reverse atom transfer radical polymerization. Characteristics of spherical MCM-41 nanoparticles were evaluated by nitrogen adsorption/desorption isotherm and X-ray diffraction. Morphological studies were also performed by scanning and transmission electron microscopy. Conversion and molecular weight evaluations were carried out using gas and size exclusion chromatography respectively. Addition 3 wt% of MCM-41 nanoparticles results in a decrease in conversion from 89 to 53%. Similar reduction behavior is also observed for molecular weight of the nanocomposites. However, polydispersity indices (PDI) values increase from 1.42 to 2.07 by the only 3 wt% addition of MCM-41 nanoparticles. A peak around 4.1 ppm which originates from hydrogen atom of terminal units of polymer chains in 1H NMR spectra in combination with low PDI values can appropriately demonstrate the living nature of the polymerization. Thermogravimetric analysis shows that thermal stability of the nanocomposites is higher than the neat polystyrene and increases by increasing MCM-41 nanoparticles content. Glass transition temperature decreases by the addition of MCM-41 nanoparticles loading as revealed by differential scanning calorimetry results.