Thiol-functionalized Silica Nanoparticles Research Articles

Effect of Surface Modification of Silica Nanoparticles with Thiol group on the Shear Thickening Behaviors of the Suspensions of Silica Nanoparticles in polyethylene glycol (PEG)

The Fine-tuning of Shear Thickening Fluids (STFs) by surface modification of silica particles has fascinated scientist’s interest worldwide as it results in performance enhancement of STF based on armor systems. In the current study, surface modified Silica nanoparticles (average diameter of 600 nm) possess thiol functional groups which were attained through a reaction with 3-mercaptopropyl-trimethoxysilane in absolute ethanol at 90 °C. Shear thickening fluid of Thiol functionalized Silica nanoparticles were prepared by sonochemical method in polyethylene glycol (PEG-200). The rheological parameters of STFs (modified and unmodified silica Nano particles) were measured using Rheometer MCR 52, Anton Par, Germany. The shear thickening behavior of thiol-based STF shows shear thickening at a higher shear rate compared to only silica-based STF with the decrease in viscosity maximum.

UV-curable superhydrophobic organosilicon/silica hybrid coating on cotton fabric for oil–water separation

With the increasing occurrences of industrial oily wastewater emissions and oil spills, considerable efforts have been made to develop superhydrophobic materials for oil–water separation. Herein, we report a facile dipping-UV curing approach to fabricate superhydrophobic organosilicon/silica hybrid coating with crosslinked network structure on cotton fabric via thiol-ene reaction between thiol-functionalized silica nanoparticles (SH-SiO2 NPs) and acryloyloxy-terminated polydimethylsiloxane (A-PDMS-A). With the optimized mass ratio of SH-SiO2 NPs to A-PDMS-A at 0.2, the water contact angle of the fabric reached 155° and the water sliding angle was 8°, exhibiting excellent water repellency. Furthermore, the superhydrophobic cotton fabric possessed self-cleaning ability and good surface stability. In addition, the fabric was successfully applied for effective oil–water separation, and the separation efficiency reached up to 99.06%. Even after 15 cycles, the separation efficiency still maintained 98.93%, demonstrating excellent reusability. Our findings stand out as a new tool to fabricate UV-curable superhydrophobic coating on cotton fabric for efficient oil–water separation.

Enhancing antibiotic recovery from its wastewater using thiol-functionalized SNPs as a collector and a novel foam separation column

Effective recovery of antibiotic from their wastewater is an important but challenging work. Here, a promising process of foam separation had been validated for the recovery of streptomycin sulfate (SS) from its wastewater and the SS concentration in wastewater was 110.0 ± 2.8 mg/L. Firstly, thiol functionalized silica nanoparticles (t-SNPs) were prepared to enhance their adsorption capacity, and they acted as the collectors to capture SS. Moreover, a novel foam separation column containing a polyethylene tube was developed to strengthen foam drainage. A low liquid holdup of the foam was achieved because the polyethylene tube contributed to accelerating the flow of entrained liquid in the exterior channels. Under the suitable conditions of pH 7.0, t-SNPs concentration 500 mg/L and volumetric air flow rate 700 mL/min, the recovery percentage and enrichment ratio of SS reached 90.1 ± 4.5% and 82.4 ± 4.1, respectively. Furthermore, desorption experiments were performed for isolating SS from the t-SNPs and the desorption percentage of SS reached 91.3 ± 4.6% after four cycles. Overall, this work had a significant meaning for the treatment of antibiotic-contaminated wastewater.

The effect of SiO2/Au core–shell nanoparticles on breast cancer cell’s radiotherapy

Introduction: Recently it has been shown that radiation dose enhancement could be achievable in radiotherapy using nanoparticles (NPs). In this study, evaluation was made to determine efficiency of gold-silica shell–core NP in megavoltage irradiation of MCF7 breath cancer cells.Materials and methods: Gold–silicon oxide shell–core NPs were obtained by conjugation of gold NP with amine or thiol functionalized silica NPs (AuN@SiO2 and AuS@SiO2). Cellular uptake and cytotoxicity of NPs were examined by fluorescent microscopy and MTT assay, respectively. MCF-7 breast cancer cells were treated with both NPs and irradiation was made with X-ray energies of 6 and 18 MV to the absorbed dose of 2, 4 and 8 Gy using Simense linear accelerator. The efficiency of radiation therapy was then evaluated by MTT and Brdu assay, DAPI staining and cell cycle analysis.Results: TEM images indicated that synthesized NPs had average diameter of 25 nm. Cellular uptake demonstrated that the internalization of AuS@SiO2 and AuN@SiO2 NPs amounted to 18% and 34%, 3 h post treatment, respectively. Nontoxicity of prepared NPs on MCF-7 cells was proved by MTT and Brdu assays as well as DAPI staining and cell cycle studies. The highest enhancement in radiation dose was observed in the cells that irradiated with radiation energy of 18 MV and absorbed of 8 Gy at NPs concentration of 200 ppm. The Brdu findings revealed that the cytotoxicity and apoptosis on MCF-7 cells are dose dependent with a significantly more death in AuN@SiO2 (amine) exposed cells (p < .05). Analysis also revealed interruption in cell cycle by demonstrating lack of cells, in S phase in amine treated cells (AuN@SiO2) at given dose of 8 Gy using 18 MV X-ray in comparison to thiol treated cells.Conclusions: Based on the results of the study it can be concluded that the gold–silicon oxide shell–core NPs could play an effective role in radiotherapy of MCF-7 breast cancer cells.

Click-based transparent durable films derived from tetrabrachius PDMS-bridged epoxy acrylates and surface modified nanosilica particles

Abstract We propose a novel tetra-arm polydimethylsiloxane-bridged aryl-ether-functional epoxy acrylate (EAAE-PDMS), which was employed as a precursor to crosslink with systematic variations (0, 1, 3, 5, 15 wt.%) of thiol-functionalized silica nanoparticles (SNs) through a thiol-ene click chemistry, resulting in transparent hybrid films (EAAE-PDMS@SiO 2 ). The unique tetrabrachius structure of EAAE-PDMS can result in significantly high crosslinking densities and high gel content of their thermosetts. The introduction of PDMS bridge in the precursor backbone and the modification of SNs are simultaneously in favor of better compatibility between the organic/inorganic components, benefiting for the distinctly improved surface mechanical properties namely scratch hardness and abrasion resistance relative to common epoxy acrylates. A sound proof is the fact that either our hybrid film derived from neat EAAE-PDMS or its mixture with thiol-functionalized SNs shows an increased 5%-mass-loss temperature at least by 90 °C and up to 7-fold enhancement in the abrasion resistance relative to the silica-free EA film. Finally, the as-made films show excellent solvent and thermal resistance and strong adhesion, providing strong potentials for application in dielectric and mechanic materials.

Silica nanoparticle-based dual-responsive nanoprodrug system for liver cancer therapy.

A thiol-terminated polyethyleneglycol (PEG)-paclitaxel (PTX) conjugate was synthesized and utilized to construct a novel drug delivery system with thiol-functionalized silica nanoparticles (SLNs) to improve the overall performance of PTX in liver cancer therapy. Drug loading was performed by coating the PTX conjugate on the surface of SLNs. The PTX-PEG/SLNs showed a binary responsive drug release behavior to esterase as well as high concentrations of glutathione. The synergic effects of these cancer cell-specific factors on the release characteristics of PTX-PEG/SLNs resulted in a significantly (P<0.01) elevated anti-cancer efficiency. This included prolonged circulation and passive tumor-targeting properties in vivo due to surface modification of PEG and targeted release of PTX inside tumor cells, which resulted in increased anti-cancer efficiency. Improving the in vitro properties of PTX-PEG/SLNs not only significantly (P<0.01) enhanced its therapeutic efficacy in a murine liver cancer model, but rendered these drug-conjugated SLNs a promising nanoprodrug system for potential use as clinical cancer therapeutics.

Stable Radiolabeling of Sulfur-Functionalized Silica Nanoparticles with Copper-64.

Nanoparticles labeled with radiometals enable whole-body nuclear imaging and therapy. Though chelating agents are commonly used to radiolabel biomolecules, nanoparticles offer the advantage of attaching a radiometal directly to the nanoparticle itself without the need of such agents. We previously demonstrated that direct radiolabeling of silica nanoparticles with hard, oxophilic ions, such as the positron emitters zirconium-89 and gallium-68, is remarkably efficient. However, softer radiometals, such as the widely employed copper-64, do not stably bind to the silica matrix and quickly dissociate under physiological conditions. Here, we overcome this limitation through the use of silica nanoparticles functionalized with a soft electron-donating thiol group to allow stable attachment of copper-64. This approach significantly improves the stability of copper-64 labeled thiol-functionalized silica nanoparticles relative to native silica nanoparticles, thereby enabling in vivo PET imaging, and may be translated to other softer radiometals with affinity for sulfur. The presented approach expands the application of silica nanoparticles as a platform for facile radiolabeling with both hard and soft radiometal ions.