Chiral Ag and Au Nanomaterials Based Optical Approaches for Analytical Applications

Abstract

Sensing of chiral compounds has gained great attentions for many decades. Chiral nanomaterials with a greater surface area, optical properties, and stability have however not been well realized in this field. Herein, strategies for the preparation of chiral Ag and Au nanomaterials are focused upon, including Ag and Au nanoparticles conjugated with chiral molecules with/without containing fluorophores, chiral nanoassemblies of Ag and Au nanoparticles, and chiral Ag and Au nanoclusters. The chirality of nanomaterials originates from their core and/or ligand, meanwhile that for nanoassemblies results from their complex spatial configuration. An emphasis is given to circular dichroism, colorimetry/UV–vis absorption, and fluorescence detection modes for sensing enantiomers and achiral analytes using the chiral Ag and Au nanomaterials. Several interesting examples for quantitation of DNA, proteins, peptides, drugs, and pollutants are provided to highlight their potential as sensitive and selective nanomaterials for enantiomer recognition and sensing of achiral analytes. Several important issues to be solved when using chiral nanomaterials for chiral recognition are specified. Some strategies for improving the sensitivity and selectivity of chiral nanomaterials for chiral recognition are suggested. The aim is to bring more attention to the potential of chiral nanomaterials for sensing important analytes such as chiral drugs.

Nanophotonic Approaches for Chirality Sensing

“…Nanomaterials have distinct optical properties that make them ideal candidates for improving the sensitivity of CD spectroscopy. − Molecular CD is inherently weak because chiral molecular structures are smaller than the wavelengths of light they are sensed with, resulting in small signals on the order of millidegrees. , Thus, large quantities of chiral molecules are required for adequate signal-to-noise ratios. , Also, chiral biomolecules absorb light in the UV region, and UV light is more challenging to measure than visible wavelengths due to requirements such as UV-transparent optics . In contrast, nanomaterials can be engineered on a larger size scale to generate stronger CD .…”

Chiral Self-Assembly of Porphyrins Induced by Chiral Carbon Dots

“…Up to now, many achievements have been made in the research of chiral nanomaterials. Among the chiral nanomaterials, chiral noble metal nanomaterials (Xu et al, 2019 ), and chiral semiconductor nanomaterials (Nakashima et al, 2009 ) have been gradually developed in recent years. However, the toxicity and high cost of metals limit their large-scale commercialization.…”

Polydopamine/Silver Substrates Stemmed from Chiral Silica for SERS Differentiation of Amino Acid Enantiomers

“…However, the related equipments with complex optical setups are currently less popular and accessible. Therefore, it is highly appreciated to develop novel strategies or methods with high sensitivity and selectivity toward the chirality information and molecular interactions involved in the enantiomeric discrimination. − …”