Chitosan embedded with Ag/Au nanoparticles: investigation of their structural, optical and sensing properties
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ORIGINAL PAPER
Chitosan embedded with Ag/Au nanoparticles: investigation of their structural, optical and sensing properties Meena 1,2 & Annu Sharma 1 & Rajiv Kumar 3,4 & Sita Ram 5 & Pawan K. Sharma 3 Received: 3 February 2020 / Accepted: 26 May 2020 # The Polymer Society, Taipei 2020
Abstract Quantitative detection of hydrogen peroxide (H2O2) is reported by utilizing an optical sensor based on the Surface Plasmon Resonances (SPR) of Ag and Au nanoparticles embedded in chitosan, a biopolymer. Ag and Au nanoparticles, fabricated by chemical reduction approach, were incorporated individually in chitosan matrix by solution casting method. Subsequently, their presence in the host matrix was confirmed using UV-visible spectroscopy, X-Ray diffractometer (XRD), High Resolution Transmission Electron Microscopy (HRTEM) and Field Emission Scanning Electron Microscopy (FESEM) along with Energy Dispersive Analysis of X-Ray (EDAX) spectroscopy. Structural changes induced in chitosan with addition of varying concentration of Ag or Au nanoparticles were studied using Fourier transform infrared (FTIR) spectroscopy. Optical energy gap of chitosan decreased from 3.82 ± 0.28 eV to 1.84 ± 0.19 eV for Ag-chitosan nanocomposite (Nc) film containing 0.50 wt% Ag nanoparticle while to a value of 2.14 ± 0.08 eV for Au-chitosan Nc film containing 0.5 wt% of Au nanoparticle. A significant difference in position and intensity of SPR absorption band was observed as a function of variable concentration of H2O2. The detection limit of these optical sensors is upto 0.3 μM concentration of H2O2. Keywords Nanocomposite . Chitosan . Plasmon . Absorption . Sensor
Introduction Chitosan is a linear cationic polysaccharide derived from the deacetylation of chitin, the second most abundant polysaccharide after cellulose [1]. Though like other biopolymers chitin is biodegradable, biocompatible and non-toxic but its applications and processing are limited due to its insolubility in
conventional solvents. Owing to this fact chitosan is derived by chemical/enzymatic deacetylation of chitin thus maintaining green properties of chitin [2]. Chitosan can be claimed as one of the best contenders for fabricating thin films owing to its excellent film-forming property. It contains free amino and hydroxyl groups which can be functionalized through binding with the cationic and anionic
Highlights • Stable Ag-chitosan and Au-chitosan Nc films were fabricated. • Optical energy gap reduces to 1.84 ± 0.19 eV and 2.14 ± 0.08 eV for Agchitosan Nc film and Au-chitosan Nc film respectively as compared to 3.82 ± 0.28 eV for chitosan. • FTIR analysis confirms the strong interaction of Ag and Au nanoparticles with chitosan. • The detection limit of these optical sensors is upto 0.3 μM concentration of H2O2. * Annu Sharma [email protected] 1
Department of Physics, Kurukshetra University, Kurukshetra 136119, India
2
Department of Physics, Dr. Bhim Rao Ambedkar Govt. College, Jagdishpura, Kaithal 136027, India
3
Department of Chemistry, Kurukshetra University, Kurukshe
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