SYNTHESIS CHARACTERIZATION AND BIOMEDICAL APPLICATIONS OF PHB PHBV COATED SILVER NANOPARTICLES (AG NPS)

Abstract

Bioplastics-capped silver nanoparticles may be anti-bacterial agents, or a general antimicrobial agent at broad spectrum as we are finding more and more applications of green, renewable, cost-effective biopolymers from microorganisms. Highly pathogenic, biofilm producing bacterial strains, e.g. S.aureus their drug-resistance nature, and support from the extracellular matrix may result in a complex illness that is very tough to cure. Metallic nanoparticles e.g. encapsulated silver (Ag) NPs have already proven to be effective against these bacteria. However, their biocompatibility and stability are some of the major disputes which should be addressed for their efficient utilization in the biomedical field. PHB biopolymer is green (renewable), degraded within the body (biodegradable) to non-toxic (biocompatible) by-products and has known applications in the field of biomedicine. Chapter 1 is the basic introduction of the field, past discoveries to biomedical future of poly-hydroxybutyrates e.g. 3-PHB and PHBV biopolymers. It is also pointing towards the objectives of the study. Natural polymers alone are not very thermostable but their nanocomposites may have better mechanical and thermal properties. Chapter 2 is the literature review and summarizing the what is already known about PHB and PHBV and what is nanotechnology, how nanomaterial differ from bulk in terms of their properties and applications. Also, this chapter contains references to all known green methods that have been used by people from time to time to synthesize nanoparticles of PHA alone or with metals. Chapter 3 summarizes the techniques and instruments that are being utilized during the study. It includes UV-Vis/ FTIR spectroscopy, DLS/zeta sizer, SEM, TEM, XRD, TGA and SPM analysis for characterizations of 3-PHB, PHBV encapsulated nanoparticles. Chapter 4 contain results of the characterization of nanoparticles, all experiments needed to study the effects of these freshly prepared nanoparticles of encapsulated silver over bacterial cells e.g. P.aeruginosa, S.aureus, and B.thuringiensis mainly and A549 alveolar adenocarcinoma cells of humans. Chapter 5 contain Concluding Remarks and Future Perspectives for further study to explore their activity against e.g. fungi or viruses. x This study is about the instant chemical reduction of AgNO3 and synthesis of PHB or PHBV (green renewable biopolymer) encapsulated silver nanoparticles e.g. PHB and PHBV stably encapsulate Ag atoms from AgNO3 by using NaBH4 as a reducing agent. The method described is found to be effective, simple, and instant. Synthesized nanoparticles are very small in size (2-25 nm) with very good stability in original colloidal solution form (zeta potential ~ 40 mV). These nanoparticles have been found to be efficiently removing S.aureus, B.thuringiensis, and P.aeruginosa, E.coli, and S.epidermidislike bacterial species and further intervention may possibly lead to the revelation of their potential as antibacterial therapeutics against biofilms. PHBV-Ag NPs are found to be more effective due to their smaller size than PHB-Ag NPs, and, having better nano-characteristics e.g. more surface roughness. Owing to GRAS status, they can be used to enhance the antibiotic abilities of the silver nanoparticles. Hence, this study legitimately provides assurance that the PHB encapsulated silver NPs holds a great promise in this novel antimicrobial field for biomedical applications, e.g. antimicrobial, anti-fouling coatings of food packets and dressing applied to the wounds to suppress infections at sites of open injury. Other Possible Applications may be in medicine, in pharmacology and in the packaging of food, sprayed foils for fast foods, and fibers.