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Title:	Fabrication and characterizatios of antibacterial regenerated biopolymers containing silver nanoparticles and graphene oxide
Authors:	Chook Soon Wei (P57343)
Supervisor:	Chia Chin Hua, Assoc.Prof.Dr
Keywords:	Nanoparticles-Analysis.
Issue Date:	19-Nov-2014
Description:	In this study, antibacterial composite materials containing silver nanoparticles (AgNPs) were produced. A green method for synthesizing AgNPs was developed using modified Tollens' procedure with glucose as reducing agent. The synthesis was carried out with the assistance of microwave-irradiation to produce AgNPs with smaller size and better homogeneity due to the rapid and homogeneous heating on the reaction medium. Besides, AgNPs-graphene oxide nanocomposite (AgGO) was produced by utilizing the opposite charges of silver ammonia complex and graphene oxide for electrostatic attraction, followed by the addition of glucose to initiate the formation of AgNPs. Graphene oxide (GO) is a graphene possessed with oxygenated functional groups which are negatively charged that can attract Ag cations and serve as nucleation site of AgNPs. The transmission electron microscope (TEM) image of the produced AgGO nanocomposite showed that the AgNPs were deposited on the GO sheets. The antibacterial results showed that the AgGO exhibited comparable antibacterial properties to the bare AgNPs although with lower Ag content. Regenerated cellulose membranes embedded with AgNPs and AgGO were produced using two different approaches. First, the as-produced AgGO was added into dissolved cellulose in sodium hydroxide/urea solution, followed by the regeneration into membrane in an acidic solution. The dispersion stability of the AgGO and AgNPs in the alkaline solution was studied and the results obtained showed that the AgGO was relatively enhanced the stability of AgNPs by the deposition on GO sheets that prevent the aggregation of AgNPs. The AgGO embedded regenerated cellulose (CM-AgGO) possessed highly porous structure compared with the neat cellulose membrane, as revealed by field emission scanning electron microscope (FESEM). Furthermore, the antibacterial test proved CM-AgGO has effectively inhibits the growth of Staphylococcus aureus and Escherichia coli. On the other hand, in situ synthesis approach using the modified Tollens' process was used to immobilize AgNPs on the respective regenerated cellulose membranes that containing GO or chitosan. GO was added into the dissolved cellulose solution and regenerated in an acidic coagulation bath to form GO-embedded cellulose membrane (CMGO). The presence of GO enhanced a greater deposition of AgNPs due to the electrostatic attraction between negatively charged oxygenated functional groups on the GO and the silver ammonia complexes. The FESEM images revealed that the CMGO exhibited a porous structure and the synthesized AgNPs were deposited on the CMGO structure. The antibacterial activity of the CMGO membrane was improved as the concentration of GO increased due to more deposited AgNPs. Additionally, chitosan coagulated-cellulose membrane (CMCS) was also prepared by the regeneration of the dissolved cellulose solution in an acetic acid bath containing chitosan. The chelation effect of chitosan that entangle on cellulose has drawn more positively charged silver ammonia complex and improved the deposition of AgNPs. Thus, the contents of AgNPs on CMCS membranes higher than that of acidic coagulated-membrane without chitosan. CMCS deposited with AgNPs exhibited strong antibacterial activity against Staphylococcus aureus and Escherichia coli. Deposition of AgNPs on the regenerated cellulose has offered potential in antibacterial applications,Ph.D
Pages:	125
Call Number:	QC176.8.N35 C485 2015
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Science and Technology / Fakulti Sains dan Teknologi

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