Smitha vijayan - Academia.edu (original) (raw)

Papers by Smitha vijayan

Wear, 2013

Engineers, material scientists are always striving to come up with improved performance of existi... more Engineers, material scientists are always striving to come up with improved performance of existing materials or completely new materials. The continuing quest for the materials with lower cost, higher strength and lighter in weight is the reason behind this. Polymer composites are the results of such extensive research and development in the field of materials. Stringent environmental guidelines by government bodies and global energy crisis have paved the way for natural fiber reinforcement in place of synthetic fiber reinforcement for polymeric composites. Tribological study of these composites is the new research area for researchers. As various mechanical systems fail due to the tribology involved in the system. The focus of this study is on the tribological behavior of natural fiber reinforced epoxy based composites. As epoxy resin is most widely used resin in polymeric composites due to its excellent mechanical properties and ease in processing. Therefore, study focuses only on the works carried out by various researchers in the field of tribology on epoxy based composites. This work will help those researchers which are interested in tribology of natural fibre reinforced epoxy based composites.

Archives of Microbiology, 2021

The agriculture sector is the building block of an economy with more than 60% of the world popula... more The agriculture sector is the building block of an economy with more than 60% of the world population depending on it for livelihood. Among the many crops, rice is the most important income source. It is the staple food for more than half of the world population. In spite of its huge demand, rice production has been dwindling due to various constraints. Chitosan nanoparticles (ChNP) are an excellent choice for agricultural applications owing to its non-toxic, biodegradable nature. Chitosan is an interesting polymer and is then partially or fully deacetylated chitin. In the present study, the effectiveness of ChNP as a growth promoter in improving the yield and biological activity of rice has been analyzed. 1 mg/ml of ChNP was applied as a seed, soil, foliar and combination treatments and the growth and yield parameters were measured to understand the best mode of application. The combination treatment of seed, soil and the foliar application was found to be most efficient. The cellular uptake of ChNP was also studied to deduce the mechanism of action. The soil toxicity of ChNP was studied prior to application and was found to be non-toxic.

Nanobiotechnology in Diagnosis, Drug Delivery, and Treatment, 2020

The emerging infectious diseases and the development of drug resistance in the pathogenic microor... more The emerging infectious diseases and the development of drug resistance in the pathogenic microorganism is a matter of serious concern. Despite the increased knowledge of microbial pathogenesis and application of modern therapeutics, the morbidity and mortality associated with the microbial infections still remains high. Therefore, there is a pressing demand to discover novel strategies and identify new antimicrobial agents to develop the next generation of drugs or agents to control microbial infections. The use of nanoparticles is gaining impetus in the present century as they possess defined chemical, optical and mechanical properties. In the present study green synthesis of silver nanoparticles by Escherichia coli has been done. Various parameters such as mixing ratio of culture supernatant and silver nitrate, media, temperature and pH for production of silver nanoparticles were optimised. The nanoparticles synthesised was characterized using SEM, FTIR and XRD. The antibacterial...

The present study establish extracellular production of silver nanoparticles (AgNP) using Fusariu... more The present study establish extracellular production of silver nanoparticles (AgNP) using Fusarium solani, from medicinal plant Withania somnifera (L.) (ashwagandha) and it’s antibacterial and cytotoxicity effects. Biological- AgNP (Bio- AgNP) were synthesized by using fungal cell free extract and characterized by SEM, TEM, UV spectroscopy, XRD, FTIR and AFM analysis. Antibacterial properties were assayed by well diffusion and cytotoxicity by RBC lysis test and MTT assay respectively. X- ray diffraction and microscopic analysis revealed the well dispersed and crystalline nature of spherical nanoparticles with a calculated size ranging from 10 - 50 nm. The Bio-AgNP exhibited significant antibacterial properties in a range of 50-100 µgml-1 against the selected clinical pathogens Escherichia coli,Pseudomonas aeruginosa, Salmonella typhi, Staphylococcus aureus and Klebsiella pneumoniae. The observed hemolysis of 3.906 % at 50 µg ml-1 suggested the safe therapeutic application of Bio ...

Microbial Pathogenesis, 2020

Rice is a major food source for more than half of the world population. It is the only crop whose... more Rice is a major food source for more than half of the world population. It is the only crop whose cultivation utilizes large area of land for food production. Recent surveys on rice production revealed that its potential yield has drastically reduced and its demand has exceeded over its production. In this context, the present study focuses on the biocontrol ability of chitosan nanoparticles (ChNP) against rice sheath blight pathogen (ShB) Rhizoctonia solani. To determine the percent disease suppression, detached leaf assay followed by greenhouse experiments were performed. The defence enzyme levels as well as the total phenol content were analysed to understand the mechanism of action of ChNP against ShB. This study recommends ChNP as a cost-effective alternative for chemical fungicides with potential biocontrol efficacy. ChNP was found to suppress 90% disease in detached leaf assay and 75% under greenhouse conditions. The enzyme specific activity of all the defence enzymes were significantly higher than the chemical control. The peroxidase, phenylalanine ammonia-lyase and chitinase enzymes were found to be the most active defence enzymes with 0.19,7.28 and 118.16 U/min/ml/mg protein compared to 0.01, 4.99 and 62.22 U/min/ml/mg protein for control. Hence, the current study suggest that ChNP, a non-toxic biodegradable biopolymer, can be an effective biocontrol agent against ShB caused by R. solani. It is a potent plant immunity booster that can be used as a suitable alternative to commercially available chemical fungicides. Further field trials in this respect are needed to determine the dosage for their application in rice fields.

BioNanoScience, 2020

Biogenic silver nanoparticles (Bio-AgNPs) have been recognized to play a major role in the fight ... more Biogenic silver nanoparticles (Bio-AgNPs) have been recognized to play a major role in the fight against multi-drug-resistant pathogens. The present study evaluates antifungal efficacy of biogenic AgNPs conjugated with a natural polymer chitosan (derived from shrimp (Penaeus monodon) shells). Bio-AgNPs used for conjugation were produced by a mycoendophyte Colletotrichum gloeosporioides (KX881911) isolated from the medicinal plant Withania somnifera (L.). During the last decade, although numerous reports on Bio-AgNPs with antimicrobial activity have been reported, insights on the usage of conjugates of Bio-AgNPs have been scarce. Candida species are responsible for severe nosocomial infections and which has developed resistance against many antifungal agents. The current study aims to evaluate the antifungal activity of Bio-AgNPs conjugated with chitosan (Ch Bio-AgNPs) on various Candida species isolated from patients. The fungicidal activity was screened by well diffusion assay and TTC assay. Antibiofilm activity against Candida species was well elucidated by Congo red agar and Crystal Violet assay. Ch Bio-AgNPs showed the potent antifungal effect at 50 μg/ml concentration on all the selected Candida species, and the disruption and distortion of cells were documented well with transmission electron microscopy (TEM). The TEM images showed adhesion and entry of Ch Bio-AgNPs into the cells and release of cellular inclusions along with cell damage and distorted cell morphology. To conclude, the study suggests that Ch Bio-AgNP is a potential antifungal agent to treat drug-resistant pathogenic Candida species.

International Journal of Biological Macromolecules, 2018

The worldwide rice production has been dwindling due to biotic and abiotic causes. Chitosan is a ... more The worldwide rice production has been dwindling due to biotic and abiotic causes. Chitosan is a proven biofunctional material that induces many biological responses in plants. However, the growth and yield increasing properties of chitosan nanoparticles (ChNP) on rice crop are not well understood. In the present work, effect of ChNP on germination of rice has been studied. Seed toxicity of ChNP was also analyzed to ensure the safety of ChNP application. The toxicity study was done according to EPA guidelines and ChNP was found to be non-toxic. Rice seeds were treated with ChNP at different concentrations for different time periods and kept for germination. Upon complete germination, the seedlings were sown in seed trays and growth was evaluated at 21days after sowing. All treatments showed better results than the untreated control. Treatment T22 (1mg/ml ChNP for 120 mins) gave the highest growth rates. Therefore we could deduce that ability of ChNP to elicit growth was associated with the concentration of ChNP and soaking time. The shelf life of ChNP was studied over a period of one year by analyzing the germination eliciting capacity on rice seeds. ChNP was found to effective for seven months when stored under room temperature.

International journal of biological macromolecules, Jan 15, 2018

Chitosan is an abundant non-toxic, biodegradable polymer with versatile applications. It is a lin... more Chitosan is an abundant non-toxic, biodegradable polymer with versatile applications. It is a linear amino polysaccharide obtained from crustacean shells. The chitosan nanoparticles (ChNP) prepared by ionic gelation of chitosan has greater activity owing to its small size. ChNP has been proved to be effective in controlling plants diseases. In this work, we have endeavoured to study the antifungal and antioxidant activity of ChNP and use of ChNP as a vegetable coating material. The activity of ChNP against selected plant pathogens Rhizoctonia solani, Fusarium oxysporum, Collectotrichum acutatum, and Phytophthora infestans were studied along with a brief account of its mechanism of action. The antioxidant activity of ChNP was also analysed. The ability of ChNP as a coating material to improve the shelf life of tomato, chilly and brinjal was also studied. The cytotoxicity effect of ChNP against L929 fibroblast cells was studied. ChNP had good antifungal activity against all selected p...

Fibers and Polymers, 2017

The present investigation describes the synthesis and characterization of novel biodegradable nan... more The present investigation describes the synthesis and characterization of novel biodegradable nanoparticles based on chitosan for biomedical applications. The presence of primary amine groups in repeating units of chitosan grants it several properties like antibacterial activity, antitumor activity and so on. Chitosan forms nanoparticles spontaneously on the addition of polyanion tripolyphosphate which has greater antimicrobial activity than parent chitosan. In the present study, chitosan nanoparticles (ChNP) were prepared by the ionic gelation method. The physiochemical characteristics of nanoparticles were analyzed using XRD, SEM, FTIR. The antibacterial activity of chitosan nanoparticles against medical pathogens Klebsiella pneumoniae, Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa was evaluated by calculation of minimum inhibitory concentration (MIC) and compared with chitosan and chitin activity. The mode of action and factors affecting antibacterial activity were also analyzed. ChNP compounds exhibited superior antimicrobial activity against all microorganisms in comparison with chitosan and chitin. The antibiofilm activity was studied using crystal violet assay and growth on congo red agar. The study is thus a good demonstration of the applicability of chitosan nanoparticles as an effective antimicrobial agent with antibiofilm activity as well.

Applied Nanoscience, 2019

Nanomedicine is an innovative approach to cancer therapy. The present study is in vitro anticance... more Nanomedicine is an innovative approach to cancer therapy. The present study is in vitro anticancer evaluation of chitosanstabilized biogenic silver nanoparticles (Ch/Bio-AgNPs) on Si Ha (human cervical carcinoma) and MDA MB (human adenocarcinoma) cells. IC 50 values of Bio-AgNP and Ch/Bio-AgNP were studied by MTT assay, antiproliferative and cell apoptosisinducing activities of the conjugate were examined by ethidium bromide/acridine orange double staining, RO analysis, DNA fragmentation, Caspase 7 and 9 assays and flow cytometry. Gene expression was studied by real-time PCR using the β-actin housekeeping gene. As a result, on MDA MB cells IC 50 value for Bio-AgNP and Ch/Bio-AgNP was 4.346 ± 0.6381 µg/ml and 0.9851 ± 0.0065 µg/ml, respectively, and on Si Ha cells it was 24.35 ± 1.390 µg/ml and 2.86 ± 0.319 µg/ml, respectively. Ch/Bio-AgNPs was a potent inhibitor on MDA MB and Si Ha cell lines with characteristic apoptosis and up-regulation of p53 and p38 genes.