Mukut Chakraborty

Anticancer (in vitro) and antimicrobial effect of gold nanoparticles synthesized using Abelmoschus esculentus (L.) pulp extract via a green route

Green synthesis of gold nanoparticles (Au NPs) using Abelmoschus esculentus (L.) pulp extract has been elaborately studied and reported here. The Au NPs have been characterized using several techniques. Optical analysis indicates adequate stability of the synthesized Au NPs, while FTIR analyses the fact that phytochemicals present in the Abelmoschus esculentus (L.) pulp extract play the key role in stabilizing the Au NPs. Morphological study shows that the nanoparticles are mostly spherical in shape with an average particle size of ∼14 nm, and these results are comparable with the particle size obtained from XRD. The selected area electron diffraction pattern indicates the crystalline nature of the Au NPs, which is further confirmed from XRD studies. The present study also demonstrates the in vitro efficacy of Au NPs against Jurkat cells. Results show that the IC50 dose of Au NPs is capable of significantly elevating intracellular reactive oxygen species and diminishing mitochondrial membrane potential, indicating the effective involvement of apoptosis in cell death. Furthermore, the synthesized Au NPs show a sufficient degree of antimicrobial activity against different types of bacteria. These results clearly show that the Abelmoschus esculentus (L.) pulp synthesized Au NPs have excellent medicinal applications.

Assessment of morphology and property of graphene oxide-hydroxypropylmethylcellulose nanocomposite films

Graphene oxide (GO) was synthesized by Hummers method and characterized by using Fourier transform infrared spectroscopy and Raman spectroscopy. The as synthesized GO was used to make GO/hydroxypropylmethylcellulose (HPMC) nanocomposite films by the solution mixing method using different concentrations of GO. The nanocomposite films were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and thermo-gravimetric analysis. Mechanical properties, water absorption property and water vapor transmission rate were also measured. XRD analysis showed the formation of exfoliated HPMC/GO nanocomposites films. The FESEM results revealed high interfacial adhesion between the GO and HPMC matrix. The tensile strength and Youngs modulus of the nanocomposite films containing the highest weight percentage of GO increased sharply. The thermal stability of HPMC/GO nanocomposites was slightly better than pure HPMC. The water absorption and water vapor transmission rate of HPMC film was reduced with the addition of up to 1 wt% GO.

Green one step morphosynthesis of silver nanoparticles and their antibacterial and anticancerous activities

Bile salts carry out a vital bioactive responsibility among the various physiologically important molecules. The use of bile acids and their conjugates in nanoscience is a novel idea, which opens up fascinating prospects and gives rise to various versatile properties. Sodium cholate, a biosurfactant which is environmentally safe, has been used to reduce and stabilize silver nitrate solution. The silver nanostructures thus produced are crystalline and anisotropic in nature and show different types of particle shapes and sizes depending on the reaction conditions including star and wire shapes which have not been reported earlier, by simply varying the reaction conditions. The silver precursor concentration and the ratio of sodium cholate to silver precursor were the key factors which controlled the morphosynthesis. The formation of the silver NPs was monitored using UV-vis spectrophotometry. The transmission electron microscopy (TEM) technique was used to study the morphology of the synthesized NPs. Fourier transform infrared (FT-IR) spectroscopy was used to identify the interaction of sodium cholate with the synthesized NP. The possible mechanistic role of sodium cholate in the reduction and stabilization of silver nanoparticles (Ag NPs) has also been discussed. The obtained Ag NPs exhibit antibacterial and anticancerous activities. The present study also explores the cytotoxic role of Ag NPs in KG-1A (human acute myeloid leukemia) and K562 (human chronic myeloid leukemia) cell lines.

In situ fluorescence of lac dye stabilized gold nanoparticles; DNA binding assay and toxicity study

Lac, a natural resin, is used to synthesize gold nanoparticles (AuNPs). This biodegradable natural fluorophore contains different laccaic acids, which consist of mainly the derivatives of red anthraquinone dye. For the first time, we report an in situ green synthesis of fluorophore stabilized AuNPs. The synthesis of AuNPs is monitored using both excitation and emission spectrophotometry, which gives us an idea about the progress of the reaction during nanoparticles synthesis. The size of the synthesized nanoparticles is visualised by TEM. The TEM data of the AuNPs are also correlated using DLS measurements, and the zeta potential values establish the stability of the nanoparticles. The FTIR spectra indicate the different groups present in lac and also their probable interactions during the reducing-cum-stabilizing process with the nanoparticles. The AuNPs are crystalline in nature, which is established by XRD analysis. The lac extract also binds with calf thymus DNA and forms a ground state complex, which is established spectrophotometrically by UV-Vis, as well as fluorimetrically. The antimicrobial tests against bacteria and the antitoxicity study have revealed that the lac stabilized AuNPs are safe and non-toxic, having the potential for clinical applications in the medical field.

Physical and electrical characterization of reduced graphene oxide synthesized adopting green route

Graphene and its related materials are important areas of research in recent years owing to their unique properties. The wide-range industrial application of graphene-related compounds has led to the development of novel and simple methods for the synthesis of graphene. In this paper, an environmentally friendly green synthesis for the partial reduction of graphene oxide (GO) to reduced GO (RGO) in a cost-effective single-step mechanism was reported. The method completely avoids the use of toxic and environmentally harmful reducing agents commonly used in the chemical reduction of GO to obtain RGO. The reduction of GO was carried out using aqueous leaf extracts of Paederia foetide L. The prepared GO and green RGO were characterized by ultraviolet–visible, Raman and Fourier transform infra-red spectroscopic analysis which showed a clear indication of the partial removal of oxygen-containing groups from the GO and the formation of RGO. The morphology of the green RGO was characterized by transmission electron and scanning electron microscopy. Dynamic light scattering was used for zeta potential measurement and correlated with the morphology of the sheets. Electrical conductivity was also measured to check the extent of reduction of GO to RGO.