Silver Nanoparticles As Fluorescent Probes: New Approach For Bioimaging

Nanotechnology is the study of the controlling of matter on an atomic and molecular scale. Generally nanotechnology deals with structures of the size 100 nanometers or smaller in at least one dimension, structural features are intermediate in between isolated atoms and bulk materials, in the range of 10 -9 to 10 -10 meters, the objects often display physical attributes substantially different from those displayed by earlier atoms or bulk materials. There are many methods for Nanoparticles synthesis but chemical reduction method is frequently used and characterized using NMR, XRD and FT-IR. Fluorescent molecules enable scientists to detect particular subunit of biomolecular complex, such as live cells with exquisite sensitivity and selectivity fluorescent. Photobleaching is a photochemical reduction of a dye or a fluorophore signal. Photobleaching creates complications in the observation of fluorescent molecules, since they will be eventually destroyed by light exposure necessary to stimulate them into fluorescing. This phenomenon is problematic in Time-lapse microscopy or fluorescent microscopy. So, Nanoparticles are new subject for bioimaging rather than fluorescent molecules because of its long fluorescent signal stability. These concerns have led to a debate among advocacy groups and governments on whether special regulation of nanotechnology is warranted. The extremely small size of nanoparticles results in the particles having a large surface area relative to their volume. In the case of silver nanoparticles, this allows them to easily interact with other particles and increases their antibacterial properties. It has been observed that when synthesized at nanoscale level, silver particles are not only able to promote enhanced optical activity, but they can also display visible fluorescence of very high intensity. Silver nanoparticles absorb and scatter light very efficiently. This strong interaction with light is due to a phenomenon called Surface Plasmon Resonance in which the conduction band electrons collectively oscillate when they are excited by light of a specific wavelength. Detection of single biological molecules requires illuminating the sample with an intense light to avoid the background noise. This gives rise to photobleaching. The strong light scattering property of silver nanoparticles decreases the required excitation intensity and fluorescence time, which reduces the rate of photobleaching significantly. These optically enhanced silver nanoparticles can be developed for a range of bio analytical applications such as biolabelling, fluorescent tagging and as biosensors