Surender Duhan

Ordered mesoporous Ag-doped TiO2/SnO2 nanocomposite based highly sensitive and selective VOC sensors

Hybrid mesoporous metal oxides show promising attributes in the field of relative gas sensors due to the combined opportunities provided by the high specific surface area and framework components. In this study, we present the synthesis of Ag-doped ordered mesoporous tin(IV) oxide–titanium(IV) oxide nanohybrids using a sequential combination of a wet impregnation and nanocasting process and demonstrate the response by exposing the mesoporous nanohybrids to ethanol gas. HRTEM and N2 adsorption–desorption results indicate that the nanohybrids prepared by nanocasting of SBA-15 as the hard template possess an ordered mesoporous structure and high surface area. It was also observed that the mesoporous Ag-(TiO2/SnO2) shows excellent response towards ethanol with concentrations ranging from 1 ppm to 500 ppm. Besides, the nanohybrid mesoporous sensor shows high selectivity towards other volatile organic compounds (VOCs) including acetone, methanol, isopropanol, benzyl alcohol and ethyl acetate. All the results indicated that the nanocast mesoporous Ag-(TiO2/SnO2) nanohybrids have great potential for applications in designing high performance practical ethanol sensors.

Highly sensitive and stable relative humidity sensors based on WO3 modified mesoporous silica

This study investigates the effectiveness of using WO3 loaded mesoporous silica nanocomposite developed using one step hydrothermal method for measuring relative humidity (RH) at room temperature. On measuring the sensing response, the nanocomposite sensor exhibits excellent linearity, negligible hysteresis, swift response and recovery time, good repeatability, and outstanding stability in 11%–98% RH range. The complex impedance spectra of the sensor at different RHs were used to explore the humidity sensing mechanism. This work could encourage a right approach to blueprint practical humidity sensors with high sensitivity, long stability and fast response/recovery time.

An excellent humidity sensor based on In–SnO2 loaded mesoporous graphitic carbon nitride

A highly sensitive and fast responsive relative humidity (% RH) sensor based on In–SnO2 loaded cubic mesoporous graphitic carbon nitride (g-C3N4) has been demonstrated in this study. The mesoporous In–SnO2/meso-CN nanohybrid was synthesized through template inversion of mesoporous silica, KIT-6, using a nanocasting process. Due to its 3D replicated cubic structure with ordered mesopores, the nanohybrid facilitates the process of adsorption, charge transmission and desorption of water molecules across the sensor surfaces. Consequently, the optimized In–SnO2/meso-CN nanohybrid exhibits excellent response (5 orders change in impedance) in the 11–98% RH range, high stability, negligible hysteresis (0.7%) and superior real time % RH detection performance. Compared to traditional metal oxide based resistive sensors with unique mesoporous/hierarchical/sheet-like morphology, the 3D mesostructured In–SnO2/meso-CN nanohybrid demonstrated a superfast response (3.5 s) and recovery (1.5 s) in the 11–98% RH range at room temperature. These results open the door for breath monitoring and show a promising glimpse for designing mesoporous 2D layered materials in the development of future ultra-sensitive % RH sensors.

Improved antimicrobial property and controlled drug release kinetics of silver sulfadiazine loaded ordered mesoporous silica

Abstract The present study deals with the loading of silver sulfadiazine into ordered mesoporous silica material by post-impregnation method and its effect on the in vitro release kinetics and antimicrobial property of the drug. The formulated SBA-15 silica material with rope-like morphology and SBA-15-silver sulfadiazine (SBA-AgSD) were characterized by UV–visible spectrophotometer, small and wide-angle powder X-ray diffraction (PXRD), field emission scanning electron microscope (FESEM) and high resolution transmission electron microscope (HRTEM). Thermo-gravimetric analysis of SBA-AgSD revealed a high loading amount of 52.87%. Nitrogen adsorption–desorption analysis confirmed the drug entrapment into host material by revealing a reduced surface area (214 m2/g) and pore diameter (6.7 nm) of the SBA-AgSD. The controlled release of silver sulfadiazine drug from the mesoporous silica to simulated gastric, intestinal and body fluids was evaluated. The Korsmeyer–Peppas model fits the drug release data with the non-Fickian diffusion model and zero order kinetics of SBA-AgSD. The antibacterial performance of the SBA-AgSD was evaluated with respect to Staphylococcus aureus, Bacillus subtilis and Pseudomonas aeruginosa. The controlled drug delivery of the SBA-AgSD revealed improved antibacterial activity, thus endorsing its applicability in effective wound dressing.

Biocompatible Smart Matrices Based on Poly (3,4-ethylenedioxythiophene)-Poly (N-isopropylacrylamide) Composite

The study investigated the use of composite of conducting poly(3,4-ethylenedioxythiophene) and temperature responsive poly(N-isopropylacrylamide) nanofibers as scaffold for tissue engineering application. The nanofibers of PNIPAm and PEDOT-PNIPAm composite were fabricated using electrospinning technique. FTIR was used to check the chemical structure of the composite while the conducting nature of the composite material was investigated by means of cyclic voltammetry. The average diameter of the PNIPAm and the composite nanofibers was investigated by using scanning electron microscopy, which indicates that the composite has some what more average diameter than the PNIPAm nanofibers alone. The biocompatibility of the material was studied by seeding L929 fibroblast cells on the nanofibers surface. It was seen that PEDOT-PNIPAm composite nanofibers shows highest cell growth and % live of around 98% indicating the use of these nanofibers as scaffold for the tissue engineering application. GRAPHICAL ABSTRACT

Influence of functionalized mesoporous silica in controlling azathioprine drug release and cytotoxicity properties

Abstract The present study is focused on functionalisation of mesoporous silica (or SBA-15) to control azathioprine drug release rate and its toxic effect. The mesoporous silica was functionalised by (γ-chloropropyl)triethoxysilicane and (3-aminopropyl)triethoxysilane (APTES) via hydrothermal process. The azathioprine was loaded into SBA-15 via post impregnation method. Azathioprine-loaded pristine and functionalised SBA-15 samples were characterised using UV–visible spectrophotometry and thermogravimetric analysis to measure the drug loading efficiency. The samples were also characterised by small and wide-angle powder X-ray diffraction, scanning electron microscope, transmission electron microscope, infrared spectroscopy and nitrogen adsorption/desorption analysis to study the structure, morphology, functionalisation and drug loading in detail. The maximum drug loading efficiency of 65(±1)% was achieved. In vitro azathioprine release profiles were studied in phosphate buffered saline (pH 7.4) and results suggested that the drug release amount could be controlled by functionalisation of carrier matrix SBA-15. Azathioprine-loaded APTES-functionalised material revealed lowest release amount of ~64.5% in 60 h. The toxicity of azathioprine was significantly reduced by loading the drug into the mesoporous pristine and functionalised silica. The controlled azathioprine release reduced its repeated administration and can reduce its toxicity and side effects. These outcomes recommend that the functionalised SBA-15 is an advantageous drug carrier for achieving extended release time.

One pot hydrothermal synthesis of ordered mesoporous SnO2/SBA-16 nanocomposites

In this work, we report a co-surfactant assisted one step synthesis of nanocomposite via direct amalgamation of SnO2 into the cubic mesoporous scaffold of SBA-16 by a facile hydrothermal method. High resolution TEM images validated that co-precipitation of both tin and silica species leads to homogeneous allocation of tin oxide nanoparticles in the scaffold of SBA-16. Gradual decrease in high surface area accompanied by loading of tin oxide in 3D-cubic channels of SBA-16 is scrutinized by N2 sorption isotherms and the untainted cubic mesoporous nature shows that the inclusion of tin oxide does not disintegrate the 3D-cubic channels of SBA-16 which is further confirmed by X-ray diffraction, energy dispersive X-ray spectroscopy and infrared absorption spectra. Finally, this method has been generalized to prepare mesoporous nanocomposites containing SnO2/SBA-16.

Saponin-loaded SBA-15: release properties and cytotoxicity to Panc-I cancer cells

In this study, first time a nanoformulation, saponin-loaded SBA-15 has been developed for an improved and continuous release. The SBA-15 nanopowder was synthesized by a hydrothermal process. Saponin was introduced into the mesoporous channels of SBA-15 and its concentration in SBA-15 was measured by UV–visible spectrophotometry. The pristine SBA-15 and saponin-loaded SBA-15 were characterized by small-angle XRD, FESEM, HRTEM, TGA, FTIR. N2 adsorption–desorption isotherms were used to measure the specific surface area and pore channel structure parameters of pristine and loaded SBA-15. Saponin release was studied in phosphate buffered saline (pH 7.4), which revealed that the release rate could be effectively controlled. The controlled drug release is highly desired for cancer treatment. The cytotoxicity of pristine and loaded SBA-15 was analyzed on Panc-I cancer cells. Both the pristine SBA-15 and saponin-loaded SBA-15 nanoparticles showed specific toxicity on the cancer cells. The preliminary results showed that saponin-loaded SBA-15 could be an effective therapeutic agent for Panc-I cancer cells.