Bio-functionalized silver nanoparticles: a novel colorimetric probe for cysteine detection

Area of Science:

• Nanotechnology
• Biochemistry
• Environmental Science

Background:

• Nanoparticle-biomolecule interactions are crucial for medical applications.
• There is a need for sensitive, rapid, low-cost, and eco-friendly biosensors.
• Disease indicators require efficient detection methods.

Purpose of the Study:

• To synthesize silver nanoparticles using an eco-friendly method.
• To develop a sensor for selective and sensitive cysteine detection.
• To investigate the mechanism of cysteine detection by silver nanoparticles.

Main Methods:

• Green synthesis of silver nanoparticles using Calotropis procera leaf extract.
• Characterization of silver nanoparticles (UV-Vis, TEM, DLS).
• Colorimetric detection of cysteine based on nanoparticle aggregation.

Main Results:

• Synthesized silver nanoparticles are spherical (10 nm) with a surface plasmon resonance peak at 421 nm.
• Silver nanoparticles selectively detect cysteine via aggregation, causing a visible color change (yellow to pink).
• Achieved an ultralow limit of detection for cysteine at 100 nM.

Conclusions:

• Eco-friendly silver nanoparticles can be effectively used for sensitive cysteine detection.
• The colorimetric method is rapid, visual, and suitable for potential application in blood plasma.
• This approach offers a novel pathway for developing green nanodiagnostic devices.