Recent developments in the chiroptical properties of chiral plasmonic gold nanostructures: bioanalytical applications.

The presence of excess L-amino acid in the Murchison meteorite, circular polarization effect in the genesis of stars and existence of chirality in interstellar molecules contribute to the origin of life on earth. Chiral-sensitive techniques have been employed to untangle the secret of the symmetries of the universe, designing of effective secure drugs and investigation of chiral biomolecules. The relationship between light and chiral molecules was employed to probe and explore such molecules using spectroscopy techniques. The mutual interaction between electromagnetic spectrum and chirality of matter give rise to distinct optical response, which advances vital information contents in chiroptical spectroscopy. Chiral plasmonic gold nanoparticle exhibits distinctive circular dichroism peaks in broad wavelength range thereby crossing the limits of its characterization. The emergence of strong optical activity of gold nanosystem is related to its high polarizability, resulting in plasmonic and excitonic effects on incident photons. Inspired by the development of advanced chiral plasmonic nanomaterials and exploring its properties, this review gives an overview of various chiral gold nanostructures and the mechanism behind its chiroptical properties. Finally, we highlight the application of different chiral gold nanomaterials in the field of catalysis and medical applications with special emphasis to biosensing and biodetection.

Fluorescence turn on detection of bilirubin using Fe (III) modulated BSA stabilized copper nanocluster; A mechanistic perception.

Hyperbilirubinemia is the condition when bilirubin exceeds normal concentration in body (19.80 mg/mL in newborns and 1.19 × 10-2 mg/mL in adults). Bilirubin encephalopathy in newborns may cause irreversible neurological disorders. Current methods for detection of bilirubin suffer from compromising accuracy. In the present work, bovine serum albumin stabilized copper nanocluster (BSA-CuNCs) was synthesized via a one pot microwave assisted method as a turn on detector for bilirubin. The synthesized BSA-CuNCs having size less than 4 nm, exhibited bright blue emission at 405 nm. Interestingly, no observable change in fluorescence emission was noticed over a wide pH range (1-11) or at high ionic conditions. However, the interaction of Fe3+ with BSA-CuNCs induces quenching of fluorescence. Moreover, the fluorescence can be regained by the addition of bilirubin over other possible coexisting biomolecules. A good linearity was observed for BSA-CuNCs based turn on probe with a Limit of Detection (LoD) 6.62 nM. Furthermore, real sample analyses were carried out with human serum and urine which showed good recovery percentage.

Blue emitting copper nanoclusters as colorimetric and fluorescent probe for the selective detection of bilirubin.

Hurdles to develop point of care diagnostic methods restrict the translation of progress in the health care sector from bench side to bedside. In this article a simple, cost effective fluorescent as well as colorimetric nanosensor was developed for the early and easy detection of hyperbilirubinemia. A stable, water soluble bovine serum albumin stabilised copper nanocluster (BSA CuNC) was used as the fluorescent probe which exhibited strong blue emission (404nm) upon 330nm excitation. The fluorescence of the BSA CuNC can be effectively quenched by the addition of bilirubin by the formation of copper-bilirubin complex. Meanwhile the copper-bilirubin complex resulted in an observable colour change from pale violet to green facilitating colorimetric detection. The prepared sensor displayed good selectivity and sensitivity over other co-existing molecules, and can be used for quantifying bilirubin with a detection limit down to 257fM. Additionally, the as-prepared probe was coated on a paper strip to develop a portable paper strip sensor of bilirubin. Moreover, the method was successfully applied in real sample analysis and obtained promising result.