Proximity-dependent isothermal cycle amplification for small-molecule detection based on surface enhanced Raman...

Area of Science:

• Analytical Chemistry
• Biotechnology
• Nanotechnology

Background:

• Accurate and sensitive detection of illicit substances like cocaine is crucial for forensic and clinical applications.
• Existing detection methods often face challenges with sensitivity, specificity, and complex sample matrices.
• Surface-enhanced Raman scattering (SERS) offers high sensitivity but requires effective signal amplification strategies.

Purpose of the Study:

• To develop a novel proximity-dependent isothermal cycle amplification (PDICA) strategy for cocaine determination.
• To enhance SERS signals using modified bio-barcode DNA and gold nanoparticles (AuNPs) as Raman probes.
• To improve assay reliability and reduce background noise using magnetic beads (MBs) as carriers.

Main Methods:

• Proximity probes designed to hybridize in the presence of cocaine, initiating PDICA.
• PDICA involves target recycling and strand-displacement amplification to generate a strong signal.
• AuNPs modified with Raman dye-labeled DNA were used as signal reporters, captured by MBs.

Main Results:

• The PDICA-SERS assay achieved a low detection limit of 0.1 nM for cocaine.
• The method demonstrated excellent selectivity for cocaine detection.
• The assay was successfully validated in human serum, indicating high practicality and reliability.

Conclusions:

• The developed PDICA strategy coupled with SERS provides a highly sensitive and selective method for cocaine detection.
• The use of MBs effectively minimized background noise, enhancing assay performance.
• This protocol shows significant potential for real-world applications in drug testing and clinical diagnostics.