Gold Nanorod Amalgamation: Machine Learning Empowered Discrimination of Biothiol and Thiol Ratios

Area of Science:

• Biochemistry
• Nanotechnology
• Analytical Chemistry

Background:

• Biothiols are vital for biological processes, and their altered levels indicate various pathologies.
• Existing detection methods struggle to monitor thiol-to-disulfide state transitions, hindering early disease detection.
• Gold nanorod (AuNR)-based colorimetric probes offer potential for visual diagnostic assays.

Purpose of the Study:

• To develop a cost-effective, sensitive multicolor ratio measuring probe for simultaneous biothiol and disulfide detection.
• To enable on-site identification, discrimination, and quantification of cysteine (CYS), glutathione (GSH), cystine (CYSS), and glutathione disulfide (GSSG).
• To quantify critical thiol-to-disulfide ratios for health monitoring.

Main Methods:

• Utilized gold nanorods (AuNRs) with size and aspect ratio modulation based on sulfhydryl group coordination with Hg2+.
• Elucidated probe functionality via etching and anti-etching mechanisms.
• Employed linear discriminant analysis (LDA) and partial least squares regression for qualitative and quantitative analysis.

Main Results:

• Achieved simultaneous visual and spectroscopic discrimination of CYS, GSH, CYSS, and GSSG using rainbow-like fingerprint patterns.
• Demonstrated broad linear concentration ranges and low detection limits for all analytes (e.g., CYS: 0.66 μmol L−1).
• Quantified thiol-to-disulfide ratios with high sensitivity (e.g., 32.648 for CYS/CYSS) and validated performance in complex matrices.

Conclusions:

• The developed AuNR probe offers a sensitive and selective platform for on-site, simultaneous monitoring of biothiols and their redox states.
• This technology facilitates early detection of pathologies associated with altered biothiol levels and thiol-to-disulfide imbalances.
• The probe's multicolor ratio measurement capability provides a powerful tool for complex biological sample analysis.