Rhodamine B embedded silver nanogranules for selective sensing of l-cysteine

Area of Science:

• Biomarker detection
• Nanomaterial-based sensing
• Fluorescence spectroscopy

Background:

• Amino acid sensing is crucial for disease diagnosis.
• Elevated L-Cysteine levels are linked to neurotoxic and coronary heart diseases.
• Developing selective and sensitive L-Cysteine sensors is an ongoing research challenge.

Purpose of the Study:

• To develop a simple and highly selective fluorescence "TURN ON" sensor for L-Cysteine detection.
• To utilize silver-centered Rhodamine B nanogranules (AgNPs/RhB) for enhanced sensing capabilities.
• To validate the sensor's performance in complex biological matrices like human serum.

Main Methods:

• Synthesis of Rhodamine B-stabilized silver nanogranules (AgNPs/RhB).
• Investigation of the fluorescence "TURN ON" mechanism upon L-Cysteine interaction.
• Characterization using FTIR and XPS to confirm AgNPs-L-Cysteine linkage.
• Evaluation of selectivity, limit of detection (LOD), and linear range in various conditions.

Main Results:

• The AgNPs/RhB nanocomposite exhibited highly selective fluorescence turn-on sensing for L-Cysteine.
• A stable covalent linkage formed between the silver nanogranules and the thiol group of L-Cysteine.
• Achieved a low limit of detection (1.084 µM) and a wide linear range (100–2200 µM).
• Demonstrated stability across varying pH and ionic strength, with excellent recovery in human serum.

Conclusions:

• The developed AgNPs/RhB nanocomposite probe offers a robust and selective method for L-Cysteine detection.
• Its stability and effectiveness in human serum highlight its potential for clinical diagnostic applications.
• This fluorescence turn-on sensor represents a significant advancement in amino acid sensing for disease monitoring.