Sensitive SERS assay for L-cysteine based on functionalized silver nanoparticles.

Area of Science:

• * Nanomaterials Science
• * Analytical Chemistry
• * Biochemistry

Background:

• * L-cysteine is a vital amino acid crucial for numerous biological functions.
• * Accurate quantification of L-cysteine is essential for understanding its biological roles and associated diseases.
• * Existing detection methods may lack the required sensitivity, selectivity, or simplicity for real-world applications.

Purpose of the Study:

• * To develop a highly sensitive and selective Surface-enhanced Raman Scattering (SERS) sensor for L-cysteine detection.
• * To utilize the anti-aggregation properties of functionalized silver nanoparticles for signal generation.
• * To establish a robust platform for L-cysteine quantification in complex biological matrices.

Main Methods:

• * Synthesis of histidine and 4-mercaptobenzoic acid functionalized silver nanoparticles (Ag NPs@His@4-MBA).
• * Design of a SERS sensing mechanism based on Hg²⁺-induced aggregation and L-cysteine-mediated anti-aggregation.
• * Characterization of the sensor performance, including detection limit, linear range, and specificity.

Main Results:

• * The SERS sensor exhibited a low detection limit of 5 nM for L-cysteine (S/N=3).
• * Linear detection of L-cysteine was achieved in the concentration range of 0.01–100 μM.
• * The sensor demonstrated successful application in detecting L-cysteine in spiked human serum samples with high recovery rates (95.0–108.1%) and low relative standard deviations (<3.3%).

Conclusions:

• * The developed SERS sensor provides a sensitive and selective method for L-cysteine detection.
• * The anti-aggregation strategy based on functionalized silver nanoparticles is effective for biosensing applications.
• * This approach offers a promising platform for developing advanced SERS biosensors for biomolecule monitoring.