Browsing by Author "Kandiah, M."

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An ecological approach for the green synthesis of silver nanoparticles using leaf extracts of six species of genus Adiantum and assessing their antibacterial, antioxidant and photocatalytic activity
(Faculty of Graduate Studies, University of Kelaniya Sri Lanka, 2022) Samarasinha, S.; Kandiah, M.
Biogenic synthesis of nanoparticles (NPs) is an efficient replacement of chemical and physical synthesis systems burdened with heavy cost and toxicity. Moreover, eco-friendly synthesis of metallic NPs is currently flourishing due to its wide applications in many fields of science, may it be in medicine or the sustainable development of the environment. This research focuses on the first report of synthesis of metallic silver nanoparticles (AgNPs) which were biosynthesized using six species of the genus Adiantum commonly known as Maiden-hair ferns. The six species which were utilized for the synthesis possess their own specialized uses in ethno medicine in different regions of the world ranging from Asia to Europe. While all six samples produced AgNPs they were first optimized under different time and temperature scales. Water extracts of the plant sample and AgNPs were assessed for antioxidant activity via Total Flavonoid Content (TFC), Total Phenol Content (TPC), Total Antioxidant Capacity (TAC), DPPH and IC50 assays. Photocatalytic activity of AHI (Adiantum hispidulum), the best sample of synthesized nanoparticles, was observed by the degradation of methylene blue. Antibacterial activity was tested using two common bacterial species Escherichia coli and Staphylococcus aureus. The TPC, TFC and TAC assays indicated high antioxidant capacity in synthesized AgNPs but contradictorily DPPH and IC50 showed lower antioxidant activity. The assessment of photocatalytic activity against methylene blue dye showed different rate constants for 100 and 500 ppm samples insinuating that concentration may enhance rate of degradation. TEM results of AHI AgNPs showed that their shapes as spherical, rod shaped, rectangular and triangular NPs. The sizes varied from 15nm-50nm. Antibacterial activity of AgNPs was higher in both Escherichia coli and Staphylococcus aureus. Thus, AgNPs biosynthesized from decorative and wild-grown species of genus Adiantum of which extraordinary medicinal and antibacterial properties have not been grasped by many is applicable in many industries around the world and can aid in the sustainable maintenance of the environment with nanotechnology.
Green synthesis and detection of antioxidative, photocatalytic and antibacterial properties of silver nanoparticles synthesized from Psidium spps. Leaves extract
(Faculty of Graduate Studies, University of Kelaniya Sri Lanka, 2022) Rathnayake, A.; Kandiah, M.
In the ever-growing field of nanotechnology, synthesis methods that use bioproducts have been proven to be a safe, non-toxic alternative to toxic chemical compounds and traditional ways of manufacture. The research presented was performed to synthesize silver nanoparticles using the green synthesis method from six species of Psidium (Guava) leaf extracts. Five of six samples produced silver nanoparticles (AgNPs) using the optimum heating condition at 90⁰C for 1 hour. The AgNPs were observed under a transmission electron microscope at the Sri Lankan Institute of Nanotechnology (SLINTEC), Homagama, to determine the morphological features, which showed circular nanoparticles of 45 nm. The band-gap energy (2.95 eV) proved that the synthesized guava AgNPs were indeed semiconductors. Water extracts tested for phytochemicals (flavonoids, quinones, carbohydrates, proteins, saponins, steroids, tannins, terpenoids and anthraquinones), showed all positive results for the apple guava and variegated guava samples. The antioxidant content of AgNPs and water extracts were determined using Total Flavonoid Content (TFC), Total Phenolic Content (TPC), Total Antioxidant Content (TAC) tests and radical scavenging methods such as DPPH and IC50. Significant difference of antioxidant activity between AgNPs and water extracts was demonstrated by ONE-WAY ANOVA analysis at P<0.05. There is a significant difference in TFC and TPC between AgNPs and water extracts although, a considerable difference between AgNPs and water extracts were not seen during TAC testing (P>0.05). The water extracts showed higher TPC, TAC, DPPH and IC50 while the AgNPs showed higher TFC. Pearson correlation demonstrated a strong positive (0.82) correlation between TAC and TPC demonstrating a simultaneous increase of both variables. Both TFC vs TAC (-0.34) and TPC vs TFC (-0.28) relationships had weak negative correlations. The degradation rate of methyl-red dye measured the photocatalytic activity of the AgNPs. The results were compared between two concentrations (100 ppm and 4000 ppm), with and without a catalyst. The degradation rate was highest with the sample of 4000 ppm with catalyst (R2= 0.74). The antibacterial activity of the water extract and AgNPs were determined using the well diffusion method for E. coli and S. aureus. Water extracts showed higher zones of inhibition than AgNPs. ONE-WAY ANOVA analysis carried out on zones of inhibition observed by water extracts and AgNPs against E. coli and S. aureus showed no significant difference. The results obtained by the tests carried out on the Psidium water extracts and AgNP samples provide biocompatible solutions to antimicrobial therapies and azo-dye degradation due to antioxidative properties that can be used to improve the quality of life.
Green synthesis of silver nanoparticles using Cinnamomum verum leaf extracts and determination of their antioxidant, antimicrobial activity and photocatalytic activity
(Faculty of Graduate Studies, University of Kelaniya Sri Lanka, 2022) Kandiah, M.; Shahna, S.
With the rapid development of Nanotechnology, its applications have influenced on all sectors of human life and opened up a spectrum of research opportunities. Green synthesis of nanoparticles had gained special attention as they are ecofriendly, non-toxic, and cost effective. In this study, five varieties of Cinnamon verum leaf extracts were used for the synthesis of silver nanoparticles (AgNPs) (Cinnamon Sri Gemunu, Cinnamon dubium, Cinnamon Sri Wijaya, Cinnamon sinharajanese and Cinnamon revulorum). The leaf samples were collected from Cinnamon Research Institute in Matara, Sri Lanka. The leaf extracts were obtained after incubating the air-dried samples at 600C for 30 minutes with distilled water. The extracts were mixed with AgNO3 and incubated at 600C, 900C and at room temperature, and all five varieties indicated a color change to pale brown confirming the presence of AgNPs and indicated a distinct peak from 420-480 nm when characterized by UV spectrophotometry. Phytochemical tests for carbohydrates, amino acids, saponins, tannins, quinones, terpenoids and glycosides were carried on the leaf extracts and antioxidant activity was determined by TPC, TFC, TAC, DPPH and IC50 assays. The results from these assays showed a high antioxidant activity in AgNPs compared to its water extracts. A dried smear of AgNP sample was dissolved with distilled water and sent to Sri Lanka Institute of Nanotechnology (SLINTECH) for Scanning electron microscope (SEM) analysis. This resulted in spherical particles of 50 nm, and they all behaved as semiconductors. The antimicrobial activity against E. coli and S.aureus was determined by well diffusion technique with saline as a negative control and Gentamycin as a positive control. There was no significant difference in the antimicrobial activity of AgNPs and the water extracts. At two different concentrations, 266 ppm and 4000 ppm, photocatalytic activity was determined for AgNPs using methylene blue under UV and sunlight. AgNPs showed a better degradation of methylene blue at 266 ppm with and without the catalyst (NaBH4). Finally, all the results concluded that Cinnamon verum is a good source of nanoparticle synthesis and can be useful in medical research and to create an ecofriendly environment.