Sudha Sadras | Pondicherry Central University (original) (raw)

Papers by Sudha Sadras

Particuology, 2015

ABSTRACT Bio-inspired eco-friendly gold nanoparticles were synthesized by a green method using aq... more ABSTRACT Bio-inspired eco-friendly gold nanoparticles were synthesized by a green method using aqueous Plumeria alba flower extract (PAFE). The use of 1% and 5% concentrations of PAFE resulted in two different sizes of P. alba gold nanoparticles, PAGNPs1 and PAGNPs2, with surface plasmon resonance (SPR) peaks at 552 and 536 nm, respectively. Size-controlled formation of gold nanoparticles was indicated by the SPR shift observed with increasing concentration of PAFE. The accurate size and morphology of PAGNPs1 and PAGNPs2 were determined by transmission electron microscope (TEM) analysis is found to be 28 ± 5.6 and 15.6 ± 3.4 nm, respectively, and those are spherical in shape. The antibacterial activity of PAGNPs1 and PAGNPs2 was tested against Escherichia coli; the small-sized PAGNPs2 exhibited better antibacterial activity with a 16-mm zone of inhibition at a concentration of 400 μg/mL. Furthermore, the catalytic activity of PAGNPs1 and PAGNPs2 was analyzed on six hazardous dyes; PAGNPs2 exhibited more pronounced catalytic activity than PAGNPs1. Among all of the dyes, 4-nitrophenol was most rapidly degraded to 4-aminophenol by PAGNPs2 within 5 min. The mechanism of catalysis in the presence of PAGNPs1 and PAGNPs2 can be described as an electron transfer process from donor NaBH4 to an acceptor. The facile green synthesis of such eco-friendly nanoparticles in bulk suggests this method has potential industrial applications.

Journal of Nanoparticle Research, 2015

The present study reports the biological synthesis of silver and gold nanoparticles from Gymnema ... more The present study reports the biological synthesis of silver and gold nanoparticles from Gymnema sylvestre leaf extract and their in vitro free radical scavenging efficacy as well as antiproliferative effect in Hep2 cells. The formation of silver (GYAgNPs) and gold nanoparticles (GYAuNPs) was confirmed by UV-visible spectroscopy. The average size of synthesized GYAgNPs and GYAuNPs was found to be 33 and 26 nm, respectively, by DLS particle size analyzer. TEM analysis indicated spherical shape of GYAgNPs and GYAuNPs and in EDX analysis they produced strong signal for silver and gold, respectively. Both GYAgNPs and GYAuNPs exhibited strong in vitro free radical quenching ability and their activity was comparable to that of GYLE. The cytotoxic effect of GYAgNPs and GYAuNPs in Hep2 cells was examined by MTT assay in which GYAgNPs displayed an IC 50 value of 121 lg ml -1 , while GYAuNPs produced up to 38 % of inhibition at the maximum concentration of 250 lg ml -1 used in this study. Distinct morphological changes were observed in Hep2 cells following treatment with GYAgNPs and GYAuNPs at 24 h, and orange-colored apoptotic bodies were located by acridine orange and ethidium bromide double-staining technique. Also, there was increase in the levels of reactive oxygen species in treated cells as indicated by 2 0 ,7 0 -dichlorofluorescin diacetate staining. Further, nuclear changes like chromatin condensation/fragmentation were also observed by propidium iodide and 4 0 ,6diamidino-2-phenylindole dilactate staining methods. These findings support that the antiproliferative effects of GYAgNPs and GYAuNPs in Hep2 cells are mediated through induction of apoptosis.

Materials Science and Engineering: C, 2015

Herein, we report the green synthesis of silver nanoparticles using Plumeria alba (frangipani) fl... more Herein, we report the green synthesis of silver nanoparticles using Plumeria alba (frangipani) flower extract (FFE) and their biological applications. The formation of frangipani silver nanoparticles (FSNPs) was confirmed by UVvisible spectroscopy and characterized by DLS particle size analyzer, SEM/EDAX, FTIR, TGA/DSC and XRD. The synthesized spherical FSNPs were found to be 36.19 nm in size as determined by DLS particle size analyzer. EDAX data and XRD pattern of FSNPs confirmed the presence and face-centered cubic (fcc) phase structure of silver. The bioactive groups C-C and C-N present in FFE were involved in the formation of FSNPs as identified by FTIR analysis. FSNPs exhibited powerful catalytic activity by reducing 4-nitrophenol to 4-aminophenol within 8 min and the other organic dyes namely methylene blue and ethidium bromide were moderately degraded. Biological activities of FSNPs are evaluated by means of antioxidant, antibacterial and cytotoxic effect. Antioxidant potential of FSNPs was assessed by various in vitro assays in which they exhibited moderate antioxidant activity. The antibacterial effect of FSNPs was tested in two different pathogenic bacterial strains and their bacteriostatic effect was confirmed by growth kinetic study in Escherichia coli. The cytotoxic effect of FSNPs in COLO 205 was analyzed by MTT assay and the IC 50 concentration was found at 5.5 and 4 μg/ml respectively after 24 and 48 h of incubation. Cytotoxic effect of FSNPs in COLO 205 cells was associated with the loss of membrane integrity and chromatin condensation which might have played a crucial role in the induction of apoptosis as evidenced in AO/EB staining.

Colloids and Surfaces B: Biointerfaces, 2015

Green synthesis of silver nanoparticles using biological entities is gaining interest because of ... more Green synthesis of silver nanoparticles using biological entities is gaining interest because of their potential applications in nano-medicine. Herein, we report the biological synthesis of Abutilon indicum silver nanoparticles (AIAgNPs) using aqueous Abutilon indicum leaf extract (AILE) and evaluation of their biological applications. TEM analysis revealed that the spherical biogenic AIAgNPs were found to be between 5 and 25 nm in size. The bioactive phyto-constituents such are condensed tannins of AILE were found to play a key role in the reduction and capping of AIAgNPs. The biological properties of AIAgNPs were premeditated as free radical scavenging activity, antibacterial effect and anti-proliferative activity. AIAgNPs were found to exhibit good free radical scavenging activities and the intense zone of inhibition displayed by them in six different pathogenic species indicate the potential antibacterial effect. Further, AIAgNPs showed a dose dependant anti-proliferative effect against COLO 205 (human colon cancer) and MDCK (normal) cells with an IC 50 of 3 and 4 g/mL and 100 and 75 g/mL, respectively after 24 and 48 h. The morphological changes, chromatin condensation and membrane potential loss induced by AIAgNPs were evidenced by AO/EB and AnnexinV-Cy3 staining. The mitochondrial membrane potential (MMP) loss and G1/S transition cell cycle arrest in COLO 205 cells was evidenced in rhodamine123 staining and FACS analysis. The high levels of ROS as shown in DCF-DA staining could have played a major role in DNA fragmentation and eventually lead to apoptosis. The mode of action through the induction apoptosis by AIAgNPs in COLO 205 cells is exciting with promising application of nano-materials in biomedical research.

European Food Research and Technology, 2014