Synthesis and Characterization of Iron, Nickel, Copper and Manganese Nanoparticles for Biomedical Application

Abstract

Nanomaterials with their reductive potentials offer wide availability and have recently aroused much interest for biomedical applications. Nowadays, nanomaterials-based colorimetric sensing is a rapidly emerging field of sensing applications. Nanomaterials are considered as the main component of colorimetric determination of hydrogen peroxide (H2O2) to replace the natural enzyme-based sensors because of some associated intrinsic drawbacks. Considering the advantageous properties of ionic liquid (IL) for various applications, significant attention has been made to the use of ionic liquid stabilized metal nanoparticles which may serve as a modulator to enhance the catalytic performance of the metal nanoparticles in the different IL reaction medium. The peroxidase-like activity of IL coated metal nanoparticles (IL-MNPs) have been evaluated for the catalytic oxidation reaction of chromogenic substrate 3,3,5,5- tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (H2O2) at an approximate wavelength of 652 nm. The synthesized metal nanoparticles (Fe, Ni, Cu, and Mn) were synthesized using a chemical reduction method. Various characterization techniques like Fourier Transform Infrared Spectroscopy [FTIR], X-ray diffraction [XRD], UV-Visible Diffuse Reflectance Spectroscopy [UV-VIS DRS], Scanning electron microscopy [SEM], X-ray energy dispersive spectrometer [EDX], Transmission electron microscopy [TEM] were employed, which confirmed the structure, nano-size and successful incorporation of metal dopant ion into the samples. The molecular structure of ionic liquid with varying cations was synthesized and confirmed by 1H-NMR spectroscopy. The obtained ionic liquid was then coated on the synthesized metal nanoparticles to achieve well dispersed nanoparticles and enhanced their conductivity. Various reaction conditions like pH, temperature, incubation time, and catalyst dosage, the volume of IL, the concentration of H2O2, and the concentration of TMB that effect the catalytic activity and the obvious change in color sensing properties of the system are optimized. The coating of [Mim]Ac on Fe0 permitted a low limit of detection 0.15 μM within a linear range of 30–300 μM H2O2 concentration and LOD value of 44 μM over the linear range of 40 μM to 1000 μM for [Mim]Ac coated Cu0 NPs. Based on the ABSTRACT xxiii color development, colorimetric detection of [Pyr]Ac@Ni0 was obtained with a detection limit (LOD) of 120 μM/L over a wide and dynamic linear range of 400- 4000 μM. Furthermore, the doping showed good effect on the sensing of metal nanoparticles. The proposed method would provide new insight as a potential candidate in monitoring hydrogen peroxide in the biological system without any complicated instrumentation. KEYWORDS: Ionic liquid stabilized metal nanoparticle, Peroxidase mimic, TMB oxidation, H2O2 decomposition, Electron transfer, Colorimetric sensing