Showing papers by "SRM University published in 2016"

Bio-Inspired Green Nanoparticles: Synthesis, Mechanism, and Antibacterial Application.

Abstract: In the recent years, noble nanoparticles have attracted and emerged in the field of biology, medicine and electronics due to their incredible applications. There were several methods have been used for synthesis of nanoparticles such as toxic chemicals and high energy physical procedures. To overcome these, biological method has been used for the synthesis of various metal nanoparticles. Among the nanoparticles, silver nanoparticles (AgNPs) have received much attention in various fields, such as antimicrobial activity, therapeutics, bio-molecular detection, silver nanocoated medical devices and optical receptor. Moreover, the biological approach, in particular the usage of natural organisms has offered a reliable, simple, nontoxic and environmental friendly method. Hence, the current article is focused on the biological synthesis of silver nanoparticles and their application in the biomedical field.

Engineered Nanomaterials for Infection Control and Healing Acute and Chronic Wounds.

Abstract: Nanoengineered biomaterials have dramatically expanded the range of tools used for infection control and to accelerate wound healing. This review thoroughly describes the developments that are shaping this emerging field and evaluates the potential wound healing applications of recently developed engineered nanomaterials for both acute and chronic wounds. Specifically, we will assess the unique characteristics of engineered nanomaterials that render them applicable for wound healing and infection control. A range of engineered nanomaterials, including polymeric-, metallic- and ceramic-based nanomaterials, that could be used as therapeutic delivery agents to accelerate regeneration of damaged dermal and epidermal tissues are also detailed. Finally, we will detail the current state of engineered nanomaterials for wound regeneration and will identify promising new research directions in infection control.

In vitro and in vivo α-amylase and α-glucosidase inhibiting activities of the protein extracts from two varieties of bitter gourd ( Momordica charantia L.)

Abstract: α-amylase and α-glucosidase digest the carbohydrates and increase the postprandial glucose level in diabetic patients. Inhibiting the activity of these two enzymes can control postprandial hyperglycemia, and reduce the risk of developing diabetes. Bitter gourd or balsam pear is one of the important medicinal plants used for controlling postprandial hyperglycemia in diabetes patients. However, there is limited information available on the presence of α-amylase and α-glucosidase inhibiting compounds. In the current study, the protein extracts from the fruits of M. charantia var. charantia (MCC) and M. charantia var. muricata (MCM) were tested for α-amylase and α-glucosidase inhibiting activities in vitro, and glucose lowering activity after oral administration in vivo. The protein extract from both MCC and MCM inhibited the activity of α-amylase and α-glucosidase through competitive inhibition, which was on par with Acarbose as indicated by in vitro percentage of inhibition (66 to 69 %) and IC50 (0.26 to 0.29 mg/ml). Both the protein extracts significantly reduced peak blood glucose and area under the curve in Streptozotocin-induced diabetic rats, which were orally challenged with starch and sucrose. Protein extracts from the fruits of the two varieties of bitter gourd inhibited α-amylase and α-glucosidase in vitro and lowered the blood glucose level in vivo on par with Acarbose when orally administrated to Streptozotocin-induced diabetic rats. Further studies on mechanism of action and methods of safe and biologically active delivery will help to develop an anti-diabetic oral protein drug from these plants.

GC-MS Analysis of Bio-active Molecules Derived from Paracoccus pantotrophus FMR19 and the Antimicrobial Activity Against Bacterial Pathogens and MDROs.

Abstract: The present investigation is focused on the study of chemical composition of a bioactive compound derived from a rumen isolate Paracoccus pantotrophus FMR19 using GC–MS and to find out the antibacterial activity of the extracted crude bioactive compounds against multidrug resistant organisms (MDROs) and other clinical pathogens. GC–MS analysis revealed that P. pantotrophus FMR19 produced eight major compounds that have been reported to exhibit antimicrobial property. The main components identified from hexane fraction are long chain alkanes, fatty alcohols, fatty acid methyl ester and aromatic hydrocarbons. These molecules are not only active against clinical pathogens such as Salmonella sp. and Proteus sp. and also effective against MDROs such as Metallo β lactamase and Pan drug resistant bacterial strains and Methicillin resistant Staphylococcus aureus.

Prediction of Crop Yield using Regression Analysis

Abstract: Yield prediction benefits the farmers in reducing their losses and to get best prices for their crops. The objective of this work is to analyze the environmental parameters like Area under Cultivation (AUC), Annual Rainfall (AR) and Food Price Index (FPI) that influences the yield of crop and to establish a relationship among these parameters. In this research, Regression Analysis (RA) is used to analyze the environmental factors and their infliction on crop yield. RA is a multivariate analysis technique which analyzes the factors groups them into explanatory and response variables and helps to obtain a decision. A sample of environmental factors like AR, AUC, FPI are considered for a period of 10 years from 1990-2000. Linear Regression (LR) is used to establish relationship between explanatory variables (AR, AUC, FPI) and the crop yield as response variable. R 2 value clearly shows that yield is mainly dependent on AR. AUC and FPI are the other two factors influencing the crop yield. This research can be extended by considering other factors like Minimum Support Price (MSP), Cost Price Index (CPI), Wholesale Price Index (WPI) etc. and their relationship with crop yield.

Synergistically Enhanced Electrocatalytic Performance of an N-Doped Graphene Quantum Dot-Decorated 3D MoS2-Graphene Nanohybrid for Oxygen Reduction Reaction.

Abstract: Nitrogen-doped graphene quantum dots (N-GQDs) were decorated on a three-dimensional (3D) MoS2–reduced graphene oxide (rGO) framework via a facile hydrothermal method. The distribution of N-GQDs on the 3D MoS2–rGO framework was confirmed using X-ray photoelectron spectroscopy, energy dispersive X-ray elemental mapping, and high-resolution transmission electron microscopy techniques. The resultant 3D nanohybrid was successfully demonstrated as an efficient electrocatalyst toward the oxygen reduction reaction (ORR) under alkaline conditions. The chemical interaction between the electroactive N-GQDs and MoS2–rGO and the increased surface area and pore size of the N-GQDs/MoS2–rGO nanohybrid synergistically improved the ORR onset potential to +0.81 V vs reversible hydrogen electrode (RHE). Moreover, the N-GQDs/MoS2–rGO nanohybrid showed better ORR stability for up to 3000 cycles with negligible deviation in the half-wave potential (E1/2). Most importantly, the N-GQDs/MoS2–rGO nanohybrid exhibited a superior met...

Carrier separation and charge transport characteristics of reduced graphene oxide supported visible-light active photocatalysts.

Abstract: Extending the absorption to the visible region by tuning the optical band-gap of semiconductors and preventing charge carrier recombination are important parameters to achieve a higher efficiency in the field of photocatalysis. The inclusion of reduced graphene oxide (rGO) support in photocatalysts is one of the key strategies to address the above-mentioned issues. In this study, rGO supported AgI-mesoTiO2 photocatalysts were synthesized using a sonochemical approach. The physical effects of ultrasound not only improved the crystallinity of AgI-mesoTiO2 but also increased the surface area and loading of the AgI-mesoTiO2 nanocomposite on rGO sheets. The low intense oxygen functionalities (C-O-C and COOH groups) peak observed in the high resolution C1s spectrum of a hybrid AgI-mesoTiO2-rGO photocatalyst clearly confirmed the successful reduction of graphene oxide (GO) to rGO. The interfacial charge transfer between the rGO and the p-n junction of heterostructured photocatalysts has decreased the band-gap of the photocatalyst from 2.80 to 2.65 eV. Importantly, the integration of rGO into AgI-mesoTiO2 composites serves as a carrier separation centre and provides further insight into the electron transfer pathways of heterostructured nanocomposites. The individual effects of photo-generated electrons and holes over rGO on the photocatalytic degradation efficiency of rhodamine (RhB) and methyl orange (MO) using AgI-mesoTiO2-rGO photocatalysts were also studied. Our experimental results revealed that photo-generated superoxide (O2(-)˙) radicals are the main reactive species for the degradation of MO, whereas photo-generated holes (h(+)) are responsible for the degradation of RhB. As a result, 60% enhancement in MO degradation was observed in the presence of rGO in comparison to that of the pure AgI-mesoTiO2 photocatalyst. This is due to the good electron acceptor and the ultrafast electron transfer properties of rGO that can effectively reduce the molecular oxygen to produce a large amount of reactive O2(-)˙ radicals. However, in the case of RhB degradation, h(+) is the main reactive species which showed a slightly increased photocatalytic activity (12%) in the presence of rGO support where the role of rGO is almost negligible. This study suggests the effective roles of rGO for the degradation of organics, i.e., the rate of photocatalytic degradation also depends on the nature of compound rather than rGO support.

Reversibility of endothelial dysfunction in diabetes: role of polyphenols.

Abstract: The endothelium, a thin single sheet of endothelial cells, is a metabolically active layer that coats the inner surface of blood vessels and acts as an interface between the circulating blood and the vessel wall. The endothelium through the secretion of vasodilators and vasoconstrictors serves as a critical mediator of vascular homeostasis. During the development of the vascular system, it regulates cellular adhesion and vessel wall inflammation in addition to maintaining vasculogenesis and angiogenesis. A shift in the functions of the endothelium towards vasoconstriction, proinflammatory and prothrombic states characterise improper functioning of these cells, leading to endothelial dysfunction (ED), implicated in the pathogenesis of many diseases including diabetes. Major mechanisms of ED include the down-regulation of endothelial nitric oxide synthase levels, differential expression of vascular endothelial growth factor, endoplasmic reticulum stress, inflammatory pathways and oxidative stress. ED tends to be the initial event in macrovascular complications such as coronary artery disease, peripheral arterial disease, stroke and microvascular complications such as nephropathy, neuropathy and retinopathy. Numerous strategies have been developed to protect endothelial cells against various stimuli, of which the role of polyphenolic compounds in modulating the differentially regulated pathways and thus maintaining vascular homeostasis has been proven to be beneficial. This review addresses the factors stimulating ED in diabetes and the molecular mechanisms of natural polyphenol antioxidants in maintaining vascular homeostasis.

Enhanced UV detection by transparent graphene oxide/ZnO composite thin films

Abstract: All solution processed transparent thin films of graphene oxide (GO) and zinc oxide (ZnO) in different compositions prepared by a simple two-step chemical synthesis method have been studied for their UV detection properties. The preparation of GO through oxidation of graphite flakes is followed by sol–gel spin coating deposition of the GO–ZnO composite films on glass substrates. The surface morphology, microstructure and composition of the samples have been studied to confirm the formation of composite thin films comprising wurtzite-ZnO nanocrystallites and GO flakes. Optical studies demonstrate that both the transparency and optical band gap of the samples as estimated from wavelength dependent transmittance curves decrease with the increase of GO content in the films, while the charge carrier concentration increases by 5 fold. The in-plane current–voltage (I–V) measurements with two silver electrodes on the GO–ZnO film show a significant enhancement of the photosensitivity in comparison to ZnO films when they are exposed to UV light of different intensities. The response time (t90-response) is nearly three times smaller for GO–ZnO composite films as compared to that of pure ZnO. This improvement is attributed to the defect state modulation and carrier density improvement of the thin films with incorporation of GO, which is encouraging to propel optical, electrical and hence optoelectronics applicability of ZnO composite based transparent devices.

5-Fluorouracil Loaded Chitosan-PVA/Na + MMT Nanocomposite Films for Drug Release and Antimicrobial Activity

Abstract: In the present study, chitosan and polyvinyl alcohol (PVA) were blended with different concentrations of sodium montmorillonite (Na+MMT) clay solution by a solvent casting method. X-ray diffraction and transition electron microscope results show that the film properties are related to the co-existence of Na+MMT intercalation/exfoliation in the blend and the interaction between chitosan-PVA and Na+MMT. 5-Fluorouracil (5-FU) was loaded with chitosan-PVA/Na+MMT nanocomposite films for in vitro drug delivery study. The antimicrobial activity of the chitosan-PVA/Na+MMT films showed significant effect against Salmonella (Gram-negative) and Staphylococcus aureus (Gram-positive), whereas 5-FU encapsulated chitosan-PVA/Na+MMT bio-nanocomposite films did not show any inhibition against bacteria. Our results indicate that combination of a flexible and soft polymeric material with high drug loading ability of a hard inorganic porous material can produce improved control over degradation and drug release. It will be an economically viable method for preparation of advanced drug delivery vehicles and biodegradable implants or scaffolds.

Stem cell secretome-rich nanoclay hydrogel: a dual action therapy for cardiovascular regeneration

Abstract: A nanocomposite hydrogel with photocrosslinkable micro-porous networks and a nanoclay component was successfully prepared to control the release of growth factor-rich stem cell secretome. The proven pro-angiogenic and cardioprotective potential of this new bioactive system provides a valuable therapeutic platform for cardiac tissue repair and regeneration.

Assesment of Pozzolanic Performance of Sugarcane Bagasse Ash

Abstract: Sugarcane bagasse ash is obtained as a by-product from cogeneration combustion boilers in sugar industries, and is reported to be a useful supplementary cementitious material in concrete. A clear evaluation of pozzolanic activity of sugarcane bagasse ash is imperative to achieve its effective utilization in concrete instead of being disposed as a waste in enormous quantities. Pozzolanic activity of raw sugarcane bagasse ash and a processed sample of the same was assessed by five different standard methods in this study. The methods used were: strength activity index test, lime reactivity test, Frattini test, electrical conductivity test, and lime saturation test. In addition, chemical and mineralogical analyses were also performed on the bagasse ash. Durability performance of concrete with bagasse ash blended cement was evaluated and compared with fly ash-based concrete. The results from the studies indicate that raw bagasse ash has low pozzolanic activity due to presence of fibrous carbon particl...

Cadmium Sulfide Nanoparticles Decorated with Au Quantum Dots as Ultrasensitive Photoelectrochemical Sensor for Selective Detection of Copper(II) Ions

Abstract: Anomalous ingestion of copper has significant adverse effects and shows acute toxicity in living organisms. Recently, photoelectrochemical (PEC) method has attracted much attention as a platform for a Cu2+ ion sensor because of its high sensitivity, selectivity, low-cost, and accurate selection compared to other conventional methods. In this work, stepwise hydrothermal and in situ chemical approaches for synthesizing cadmium sulfide nanoparticles (CdS NPs) for decorating gold quantum dots (Au QDs) are presented, along with notable PEC performance. The amount of Au QDs loaded on the CdS NPs had a significant influence on the PEC performance. CdS NPs-Au QDs-2 with 1.0 mmol % Au QDs demonstrated an exceptional photocurrent density of 350.6 μA cm–2, which was 3.7-, 2.2-, and 2.0-fold higher than those of CdS NPs, CdS NPs-Au QDs-1 (0.75 mmol %), and CdS NPs-Au QDs-3 (1.25 mmol %), respectively. Femtosecond transient absorption dynamics of the ground state recovery showed a buildup time of 243 fs for Au and 268...