Navneet Sharma

Preparation and catalytic applications of nanomaterials: a review

Catalysts play a very important role in the chemical industries. Catalysts have been used in processes like the workup of fuels such as oil, gas and coal, purification of effluents and industrial waste gases etc. Heterogeneous catalysts are gaining much attention compared to homogeneous catalysts as they confer more selectivity and provide better yield. Research in new catalytic materials or optimization of existing catalyst systems is of enormous importance in order to increase the efficiency of the catalyst, resulting in higher product yields and purities. Currently, the research is more focused towards nanostructured catalysts with enhanced physiochemical properties. Nanoscale catalysts have high specific surface area and surface energy, which ultimately lead to the high catalytic activity. Nano-catalysts improve the selectivity of the reactions by allowing reaction at a lower temperature, reducing the occurrence of side reactions, higher recycling rates and recovery of energy consumption. Therefore, these are widely used in green chemistry, environmental remediation, efficient conversion of biomass, renewable energy development and other areas of interest. In this review the prospects, paradox and perspective of the preparation and catalytic application of nanomaterials in organic synthetic chemistry is reviewed, and an outlook of their developments is discussed.

Enhanced tumor uptake, biodistribution and pharmacokinetics of etoposide loaded nanoparticles in Dalton's lymphoma tumor bearing mice.

Background: Nanotechnology plays a remarkable role in the field of the treatment of Lymphomas associated with tumor. Objective: The purpose of this study is to determine and to compare the tumor uptake, biodistribution and pharmacokinetics of radiolabeled etoposide and etoposide loaded nanoparticles in Daltons Lymphoma tumor bearing mice and healthy mice. Materials and Methods: Etoposide loaded nanoparticles were prepared by nanoprecipitation technique using the poly (lactic-co-glycolic) acid (PLGA) in the presence of Pluronic F 68 (F 68) as a stabilizer and characterized by particle size analyzer, zeta potential and transmission electron microscope. Etoposide and etoposide loaded nanoparticles were labeled with Technetium-99m (Tc-99m) by the direct method and various quality control tests were carried out. The labeling parameters like labeling efficiency, stability, etc., were optimized to get high labeling efficiency as well as stability of the labeled formulations. Tc-99m labeled formulations were administered intravenously in Balb C mice and their biodistribution and pharmacokinetics were determined. Results: Mean size of the etoposide loaded PLGA nanoparticles was found to be 105.1 nm. The concentration of both free etoposide and nanoparticles increased with time and showed higher tumor concentrations of both free etoposide and nanoparticles increased with time and showed higher retention, indicating their applicability in effective and prolonged tumor therapy. Nuclear scintigraphic images confirm the presence of labeled complexes at the site of tumor for 24 h at higher concentration than in the normal muscles. Conclusion: This study indicated higher tumor affinity and targeting properties of etoposide loaded nanoparticles than free etoposide.

p-Tertbutylcalix[4]arene nanoemulsion: preparation, characterization and comparative evaluation of its decontamination efficacy against Technetium-99m, Iodine-131 and Thallium-201.

This study aimed to develop p-tertbutylcalix[4]arene o/w nanoemulsion for decontamination of radioisotopes from skin. Formulation was characterized using dynamic light scattering (DLS), transmission electron microscopy (TEM), multi-photon confocal microscopy techniques and in vitro dissolution studies. In vivo evaluation of nano-emulsion was done using nuclear medicine technique. Stability studies and dermal toxicity studies were also carried out. Comparative decontamination efficacy (DE) studies were performed on synthetic human tissue equivalent material and Sprague Dawley rat against three commonly used medical radioisotopes, i.e., Technetium-99m ((99m)Tc), Iodine-131 ((131)I) and Thallium-201 ((201)Tl). Decontamination was performed using cotton swabs soaked in nanoemulsion at different time intervals of contaminants exposure. Whole body imaging and static counts were recorded using gamma camera before and after each decontamination attempt data was analyzed using one way analysis of variance (ANOVA) and found to be statistically significant (p<0.05). DE of the nanoemulsion loaded with p-tertbutylcalix[4]arene was observed to be 88±5%, 90±3% and 89±3% for (99m)Tc, (131)I and (201)Tl respectively. Dermal toxicity studies revealed no significant differences between treated and control animals. Skin histopathology slides with and without API (Active pharmaceutical ingredients) also found to be comparable. p-Tertbutylcalix[4]arene loaded nanoemulsion shows great promise for skin decontamination against broad ranges of radiological contaminants besides being stable and safe.

Para-tert-butylcalix[4]arene as promising complexing agent for removal of the strontium from the aqueous medium

Strontium-90 is one of radioactive nuclear fallout products, can cause serious health effects. Efficient techniques are needed to remove radioactive strontium from contaminated persons. In this study complexation properties of the p-tert-butylcalix[4]arene has been evaluated against cold strontium nitrate. Ultra violet-visible (UV-vis) and fluorescence spectrophotometric techniques were used for the qualitative analytical screening and the inductively coupled plasma-atomic emission spectrometry (ICP-AES) technique used for the quantitative complexation of p-tert-butylcalix[4]arene with strontium nitrate. UV-vis, fluorescence spectroscopy and ICP-AES studies confirmed the complexation of p-tert-butylcalix[4]arene and strontium. Extraction study of strontium from picric acid by trans-chelation method proves that p-tert-butylcalix[4]arene is nearly 87% ± 3% effective. Complexation can be attributed to the cation-lone pair interaction and the bonding between the Sr 2+ and the hydroxyl group of the p-tert-butylcalix[4]arene implying its promise as a complexing agent for the removal of strontium.

Ex-vivo complexation, skin permeation, interaction and cytodermal toxicity studies of p-tertbutylcalix[4]arene nanoemulsion for radiation decontamination

Aims: p‐tertbutylcalix[4]arene loaded nanoemulsion has been designed, characterized and evaluated for skin decontamination of radionuclides of interest in nuclear and radiological emergencies. Further, nanoemulsion was evaluated for Ex‐vivo complexation, skin permeation, interaction and cytodermal toxicity. Materials and methods: Ex‐vivo skin complexation studies were conducted using High‐resolution sector field inductively coupled plasma mass spectroscopy (HR‐SF‐ICPMS). Skin studies at dermal and cyto‐dermal level have been carried out using techniques such as florescence microscopy, Differential scanning calorimetry (DSC), Flow cytometry, Confocal microscopy, Prestoblue and Comet assay. Key findings: HR‐SF‐ICPMS study confirmed > 95% complexation of surrogate nuclides of thallium and Iodine applied on excised rat skin mounted over Franz diffusion cell. Temporal analysis of aliquots obtained from Franz diffusion cell using UV–Vis absorption spectroscopy indicated that only 3.37% of formulation permeates through the skin. Skin penetration study of rhodamine 123 nanoemulsion carried out using florescence microscopy confirmed that formulation remains localised in epidermis of rat skin. DSC data confirmed skin compatibility of nanoemulsion, as no lipid extraction was observed from skin. In‐vitro cell viability and cellular uptake assays performed on human skin fibroblasts prove no cellular uptake and cytotoxic effects. Comet assay, cell cycle arrest, and apoptosis‐inducing mechanistic studies prove that prepared nanoemulsion is safe at cellular level. Significance: Taken together, data indicate that p‐tertbutylcalix[4]arene nanoemulsion is both effective and safe formulation to use on skin for radio‐decontamination. Graphical abstract Figure. No caption available.

Nanotechnology-based drug delivery systems: Challenges and opportunities

Abstract There is a need of a carrier that can deliver drugs to the targeted cells and organs, where it can prolong and localize its effect, interacting with the diseased part of the organ specifically to obtain the maximum therapeutic efficiency. There are various methods aimed at the packaging of drug molecules in nanoparticles that can specifically deliver the drug to the pathological area. These nanoparticles are designed in a way that they target the affected region of the particular organ without interacting with the healthy part. Nanoparticles have the ability to cross the cell membrane easily so that it is targeted to the diseased tissue, which in turn decreases the rate of drug doses that have a more uniform effect, reducing the side effect of drug. However, there are various ways to synthesize nanoparticles for packaging of drug compounds and they require a systematic review to analyze their operational efficiency, safety, up-scaling and costs. Therefore, this chapter undertakes a detailed investigation of various factors that influence nanoparticle-based drug delivery systems.

Preparation, characterization and evaluation of the zinc titanate and silver nitrate incorporated wipes for topical chemical and biological decontamination

Chemical and biological warfare agents have detrimental effects on biological systems. These agents are rapidly absorbed through skin and hence warrant immediate decontamination. Zinc titanate (ZnTiO3), is a well-proven moiety used for neutralizing chemical warfare agents (CWA) and silver is widely used as an antibacterial agent. Spacer fabric sheet, due to its ability to hold large amount of agents, was hydrothermally treated with silver nitrate (AgNO3) and incorporated with nano ZnTiO3 to prepare decontamination (deconwipes). Prepared deconwipe was characterized using X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). Uniform deposition of nano ZnTiO3 and AgNO3 in the wipe was demonstrated by SEM and XRD. In-vivo dermal decontamination efficacy of the prepared deconwipe was evaluated against nerve agent simulant (diethylchlorophosphate; DCP) and sulfur mustard simulant (2‑chloroethyl ethyl sulfide; CEES) on rat model using SEM, Flow Cytometry, Comet Acetylcholinesterase (AChE) inhibition assay and Organ Histopathology. In-vitro antibacterial and antifungal efficacy of the prepared deconwipe was evaluated using growth inhibitory efficacy techniques followed by SEM analysis. SEM and histopathology at dermal level revealed the decontamination efficacy of the prepared deconwipe. Nearly 90% decrease in AChE inhibition was observed in decontaminated rat in place of rate model as compared to the DCP contaminated rats. No significant attenuation was observed in DCP and CEES-induced cell cycle distribution and DNA damage analysis in decontaminated group. Furthermore, >95% inhibition of bacterial and fungal growth, proved its antibacterial and antifungal activity respectively. Thus, prepared deconwipes exhibit promising skin decontamination property against Chemical and biological contaminants.