Thesis Abstract and Dissertation Abstracts

The sand dune vegetation has a significant role to play in the coastal regions through prevention of sand erosion by decreasing wind speed at ground level. It stabilizes the dune habitat and migrates natural disturbances such as salt sprays, accretion wave action etc. Citrullus colocynthis is one of the coastal sand dune floral species with medicinal and economical importance. Based on these assessments, we have conserved the plant species using micro propagation method especially stem explants. From these studies, we have derived different types of calli such as Compact, hard greenish white, yellowish green and green callus. Among various types of phyto hormones, the maximum number of calli induction was achieved from stem explants on MS medium enriched with 0.5 mg L-1 IAA, 2,4-D and 1ppm of 6-BA which yielded morphogenic compact hard greenish white calli at a frequency of 80%. In vitro shoots were excised from shoot clumps and transferred to rooting medium containing 6-benzyl adenine (6-BA, 3.0 mg/l) with 0.2% activated charcoal. In vitro raised plantlets with well developed shoots and roots were transferred to polythene bags containing sterile soil rite and acclimatized after which the successfully adapted plants were transferred to the pots under full sun where they grew well without any detectable phenotypic variations.

Green synthesis of silver nanoparticles from stem derived callus tissues has been achieved in the first time of sand dune species Citrullus colocynthis and characterized by using UV-Spectrophotometer, AFM, SEM and FT-IR analysis. From these analyses, we have found spherical shaped silver nano particles in the range between 25 – 75 nm in size. The synthesized silver nano particles stabilized with poly vinyl alcohol for further studies. The average number of atoms per nanoparticles are N = 3837233.003. The molar concentration of the silver nanoparticles solution in our present study is 2600 nM / 10 mL.

The application of silver nanoparticles has been reported in significant antibacterial activity against biofilm forming bacteria such as E.coli (10.1 mm), V. paraheamolyticus (10.1 mm), P. aeruginosa (6 mm), Proteus vulgaris (6 mm) and L. monocytogens (8 mm) and  were isolated from the boat hull. Also stabilized silver nanoparticles evaluated their cytotoxicity activity against HEp-2 cell line by MTT assay. Silver nanoparticles at 500 nM decreased the viability of HEp-2 cells to 50 % of the initial level, and it was chosen as the IC50. Longer exposures resulted in additional toxicity to the cells. These findings confirm the cytotoxicity properties of silver nanoparticles, and suggest that they may be a cost-effective alternative in the treatment of HEp-2 cell lines.

Thesis Images:
	Different type of calli (click to enlarge)