Arun Kumar Shukla

Development of a nanocomposite ultrafiltration membrane based on polyphenylsulfone blended with graphene oxide

In the present study, graphene oxide (GO) was incorporated as a nanoadditive into a polyphenylsulfone (PPSU) to develop a PPSU/GO nanocomposite membrane with enhanced antifouling properties. A series of membranes containing different concentrations (0.2, 0.5 and 1.0 wt.%) of GO were fabricated via the phase inversion method, using N-methyl pyrrolidone (NMP) as the solvent, deionized water as the non-solvent, and polyvinylpyrrolidone (PVP) as a pore forming agent. The prepared nanocomposite membranes were characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM), and were also characterized with respect to contact angle, zeta potential and porosity, mean pore radius, tortuosity and molecular weight cut-off (MWCO). Thermogravimetric analysis (TGA) and tensile testing were used to measure thermal and mechanical properties. The membrane performance was evaluated by volumetric flux and rejection of proteins, and antifouling properties. According to the results, the optimum addition of 0.5 wt% GO resulted in a membrane with an increased flux of 171 ± 3 Lm−2h−1 with a MWCO of ~40 kDa. In addition, the GO incorporation efficiently inhibited the interaction between proteins and the membrane surface, thereby improving the fouling resistance ability by approximately 58 ± 3%. Also, the resulting membranes showed a significant improvement in mechanical and thermal properties.

Green synthesis and antifungal activity of Al2O3 NPs against fluconazole-resistant Candida spp isolated from a tertiary care hospital

Eco-friendly and cost effective Al2O3 NPs were synthesized by a green method using a leaf extract of Cymbopogon citratus. The characterization of the synthesized NPs was performed by XRD, HR-TEM, EDS, AFM, DLS, and zeta potential. To our knowledge, for the first time, the antifungal activity of Al2O3 NPs against various Candida spp isolated from oropharyngeal mucosa of HIV+ patients has been investigated. The antifungal potential of Al2O3 NPs has been assessed by determining minimum inhibitory concentrations (MIC), minimum fungicidal concentration (MFC), growth kinetics, and well diffusion methods. The minimum concentration at which Al2O3 NPs inhibit the growth of Candida spp were 250–500 μg ml−1 and more or less no growth has been observed at higher concentration (i.e., 1500 μg ml−1) when incubated for 48 h. The mechanisms of Al2O3 NPs–Candida cell biointerface interaction and its intracellular localization were further characterized by SEM and HR-TEM. The electron microscopic analysis shows that Al2O3 NPs not only attach to the surface but also penetrate inside the Candida cells and disrupt the morphological as well as physiological activity that led to the death of the cells. Due to the scavenging potential of Al2O3 NPs, the antifungal activity of Al2O3 NPs is mild towards tested yeast spp and that is why these NPs suppressed the growth of yeast cells at higher concentration. The result obtained in this study shows that Al2O3 NPs inhibit the growth of fluconazole susceptible and fluconazole resistant C. albicans and C. dubliniensis in a similar manner regardless of their drug resistant mechanisms. Thus, the present study revealed that Al2O3 NPs may be a promising remedy for the development of anticandidal agents and play an important role for sustained controlled drug delivery in medical implants and for therapeutic coatings on implantable devices used in orthopedics and dentistry.

Electron microscopic ultrastructural study on the toxicological effects of AgNPs on the liver, kidney and spleen tissues of albino mice.

The present study deals with the intraperitoneal administration of 500, 1000, 3000, and 5000mg/kg of AgNPs in albino mice for 28 days to evaluate the potential toxicological effects of AgNPs on blood biochemical parameters and to investigate the light and electron microscopic histopathological alterations on three major targets organs i.e., liver, kidney and spleen. The AgNPs was well tolerated and no mortality was observed even at the highest dose i.e., 5000mg/kg. Mice treated with 500 and 1000mg/kg AgNPs did not show significant behavioral, biochemical and ultrastructural pathological changes. Mice treated with 1000mg/kg AgNPs produces little ultrastructural alteration in liver, kidney and spleen. However, mice treated with 3000 and 5000mg/kg AgNPs revealed significant changes in biochemical parameters. Electron microscopic ultrastructural investigation of liver and kidney shows that the administration of 3000 and 5000mg/kg AgNPs revealed irregularity in the nuclear membrane, nuclear chromatin condensations, degenerated hepatocytes, swollen and pleomorphic mitochondria with distorted cristae, extensive dilation of rough endoplasmic reticulum, destructed cytoplasm, hypertrophied and fused podocytes and thickened basement membrane in the endothelial cells of the proximal tubules. The spleen sections at 3000 and 5000mg/kg AgNPs revealed megakaryocytes hyperplasia, lobulations, invaginations and folding of nuclei and nuclear membrane. The present research indicates that AgNPs were well tolerated at the lower doses, but significant alterations in liver, kidney and spleen were observed at the higher doses tested. It is, therefore, suggested that further studies are needed for the minimization of the observed side effects, especially at higher doses before AgNPs being applied in pharmaceutical application.

Removal of heavy metal ions using a carboxylated graphene oxide-incorporated polyphenylsulfone nanofiltration membrane

We investigate the removal of heavy metal ions from synthetic contaminated water on a laboratory scale using a carboxylated-graphene oxide (GO)-incorporated polyphenylsulfone (PPSU) nanofiltration membrane (the so called PPSU/carboxylated-GO nanocomposite membrane). The prepared membranes were characterized with respect to the rheology of the doping solutions and based on the morphology, topography, and charge density of the membranes. Spectroscopic analysis of the membranes was also performed. The nanofiltration performance was demonstrated by the removal of five heavy metal ions (arsenic, chromium, cadmium, lead, and zinc). The effects of carboxylated-GO on the membrane molecular weight cut-off, hydraulic permeability, and heavy metal ion removal performance were investigated with respect to different factors, including feed concentration from single ions, transmembrane pressure (TMP) with mixed ions, and permeate flux. The addition of carboxylated-GO produced a membrane with enhanced properties that exhibited superior performance. Increasing the feed concentration and TMP did not affect the removal of anions; however, the removal of cations slightly decreased with the resulting membrane. The maximum removal rates of heavy metal ions were >98% and ∼80% for the anions and cations, respectively, and an enhanced volumetric flux of 27 ± 3 L m−2 h−1 was observed. This result is based on the Donnan exclusion principle, which is attributable to the surface charge of −70 mV and the order of the hydrated metal radii. The prepared PPSU/carboxylated-GO nanocomposite membrane provided impressive heavy metal ion removal and showed an acceptable volumetric flux under the applied parameters; this work demonstrates very economically advantageous conditions for heavy metal ion removal.

Bacilli as Biological Nano-factories Intended for Synthesis of Silver Nanoparticles and Its Application in Human Welfare

The search of eco-friendly technologies for nano-synthesis is significant to expand their applications in human welfare. Nowadays, various inorganic nanoparticles with beneficial features have been synthesized via physical, chemical, and biological means. Significant biological applications of silver nanoparticles include on-infectious microbes, target drug delivery, cancer and vector-borne disease control. Their syntheses have been tested from plant fungi, bacteria, and viruses. The bacterial mediated synthesis of silver, gold, zinc and other metal leads to a milestone in nano-medicines. Thus, in this review, we focus on the contribution of Bacilli in the synthesis of silver nanoparticles, the mechanism of action and their potential application in the welfare of human beings.

Antimicrobial and antifouling properties of versatile PPSU/carboxylated GO nanocomposite membrane against Gram-positive and Gram-negative bacteria and protein

Biofouling is a serious issue in membrane-based water and wastewater treatment as it critically compromises the efficacy of the water treatment processes. This investigation demonstrates the antimicrobial and antifouling properties of a nanocomposite membrane system composed of carboxyl-functionalized graphene oxide (COOH-GO) and polyphenylsulfone (PPSU). The PPSU/COOH-GO nanocomposite membrane exhibited excellent antimicrobial properties, achieving maximum bacteriostasis rates of 74.2% and 81.1% against the representative Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa, respectively) and 41.9% against the representative Gram-positive bacterium (Staphylococcus aureus). The PPSU/COOH-GO nanocomposite membrane inhibited the attachment, colonization, and the biofilm formation of three species. Antifouling was assessed through filtration experiments using a model foulant bovine serum albumin (BSA). The fouling mechanisms were investigated by Hermia’s models (complete blocking, intermediate blocking, standard blocking, and cake formation), and the analysis involved fitting the volumetric flux decline experimental data to models. The fouling study revealed a less irreversible fouling and increased flux recovery ratio for the PPSU/COOH-GO nanocomposite membrane. Complete blocking of pores and cake formation were the major fouling mechanisms for the membrane.

Methods of Screening-Purification and Antimicrobial Potentialities of Bacteriocin in Health Care

BACKGROUND Bacteriocin have been tested as safe and effective alternative molecules over the currently used chemotherapeutic agents. Thus, being an important clinical significance, its screening and recovery methods along with its application are poorly described. Therefore, their screening, purification strategies and utilities must me extended. Thus, in this review, we, summarize potential application, various screening and purification methods used for recovery of bacteriocins. METHODS To complete this review, many reviews and previously published reports were studied. We, concentrated on review question and exclusion and inclusion criteria. The quality of content was evaluated by the quality the quality contents evaluation method. The standard method is used to describe the useful contents of available resources and appraised. RESULTS One hundred twenty research and review reports were used to complete this report. Sixty reports were used to make a collective information on screening and production of Bacteriocin Eighty two papers were used to explore the antimicrobial, therapeutic, diagnostic etc potentialities of bacteriocin in diverse field. The summarize form of data also presented in the form of tables and figures. This review describes the various methods and parameters that must be considered during the screening and purification methods. Moreover, the useful information is collected in regard represent it therapeutic potentialities in various fields for the welfare of human being. CONCLUSIONS The conclusion of this review presented the significance of a fundamental framework for planning to understanding the basic requirement needed for fast, cost effective screening and purification of bacteriocins. The summered area of their utilities also helpful to extend the research field of bacteriocin. Thus, this report would be useful not only to scale up the screening and production strategies faster at economical rate, but also provides a platform to extend the research field of bacteriocin in many ways.