Surface-enhanced Raman spectroscopy of one and a few molecules of acid 4-mercaptobenzoic in AgNP enabled by hot spots generated by hydrogen bonding.

The present study reports a direct approach to generate efficient hot spots using a nonresonant molecule bound to the inner part or hot spots that can increase the SERS sensitivity to obtain spectra of one and a few molecules. The 4-Mercaptobenzoic acid (4-MBA) adsorbate, connected to the Ag surface by a thiolate-Ag bonding, was able to trigger a self-assembly process of AgNP, which occurred by cooperative hydrogen bonds between the carboxylic groups of 4-MBA located in different nanoparticles when the pH was adjusted to 4. The self-assembly structure was characterized by UV-Vis spectroscopy and SERS (Surface Enhancement Raman Scattering), and DFT-based calculation of the model complex [AgNP-(4-MBA)-AgNP] was employed to improve the understanding of the self-assembled complex formation through the comparison of calculated and experimental SERS spectra.

Aptasensor based on a flower-shaped silver magnetic nanocomposite enables the sensitive and label-free detection of troponin I (cTnI) by SERS.

Acute myocardial infarction (AMI) is nowadays the leading death cause worldwide. For that reason, the early diagnosis of AMI is of central importance to reduce the risk of death. In this sense, aptamer-based sensors for surface-enhanced Raman spectroscopy (SERS aptasensors) emerged as an interesting alternative for future high-performance diagnostic tools.