Novel in-Situ Synthesis of Cellulose Agnps Characterization and Antibacterial Properties

Many bacteria are harmless and even highly helpful but a lot of them can cause hundreds of illnesses [1]. Therefore, there exists a need to develop antibacterial supports which exhibit satisfactory antibacterial properties allowing the protection of the human body. Cellulose is one of the most abundant biopolymers in the nature. It is a renewable material which exhibited hygroscopicity, non-toxicity, biocompatibility, biodegradability and chemical reactivity. It is a carbohydrate polymer composed of repeating D-glucopyranose units and consists of three hydroxyl groups per a hydroglucose unit conferring the cellulose molecule a high degree of functionality. The materials based on cellulose and its derivatives have been employed in a large variety of applications such as textile, food, paper production, biomaterials and pharmaceuticals [2-4]. Functionalization of cellulose with nanoparticles has attracted great attentions of researchers in recent years. A number of studies have been investigated to improve functions of this material such as antibacterial treatment [5]. Among different metals, silver is by far the most widely used antibacterial agent because of its efficiency and its strong toxicity against many forms of both gram-positive and gram-negative bacteria [6]. The structural differences between the two types of bacteria lie in the organization of a key constituent of the membrane, peptidoglycan. Gram negative bacteria display only a thin peptidoglycan layer (≈2-3 nm) between the cytoplasmic membrane and the outer membrane [7]. However, Gram-positive bacteria lack the outer membrane but have a peptidoglycan layer of about 30 nm thick [7]. The Ag metal has the capacity to attach to bacterial cell membranes, to enter and attack the respiratory chain of the cell, hence inducing the death of the bacteria [7]. Ag NPs have been added to a variety of polymeric fibers and have shown successful antibacterial activity [8-11]. In this investigation, nano silver particles were introduced on the structure of a cellulosic material (a bandage) via a chemical reduction method using sodium borohydride (NaBH4) in the presence or not of polyvinyl pyrrolidone (PVP) as stabilizer agent. The in situ direct metallization method was applied in the attempt to obtain a high loading amount and strong bonding force of Ag NPs on the cellulosic surface, thus evading the Ag+ contamination problem. The presence of Ag NPs on the surface of the used support was verified by Fourier transform infrared spectroscopy and DSC characterizations. The impact of the adopted treatment on some mechanical properties of the tested fabric was then evaluated. Finally, the survey of the bacterial activity of loaded Ag NPs cellulosic support was evaluated against gram positive and gram negative bacteria.