Fluctuation-resilient ratiometric SERS enabled by programmable aptamer disassembly for pump-free microfluidic AKI...

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Nanotechnology

Background:

• Early diagnosis of acute kidney injury (AKI) is crucial but challenged by slow biomarker detection and signal variability.
• Existing methods for quantifying biomarkers like neutrophil gelatinase-associated lipocalin (NGAL) and cystatin C (Cys C) are often time-consuming and require controlled laboratory settings.

Purpose of the Study:

• To develop a rapid, reliable, and self-calibrated microfluidic platform for simultaneous quantification of NGAL and Cys C for early AKI assessment.
• To overcome limitations of delayed biomarker kinetics and signal fluctuations in decentralized testing environments.

Main Methods:

• Development of a pump-free, capillary-driven microfluidic chip utilizing aptamer-ratiometric surface-enhanced Raman scattering (SERS).
• Employing a Y-shaped aptamer architecture for target binding-induced signal generation and a substrate-embedded internal standard for self-calibration.
• Simultaneous detection of NGAL and Cys C using Au@Ag SERS tags with dual-biomarker analysis completed within 15 minutes.

Main Results:

• Achieved low detection limits (1 pg/mL for NGAL, 34 pg/mL for Cys C) with high linearity (R² > 0.99).
• Demonstrated biomarker elevation in a rat AKI model preceding histopathological changes, indicating early detection capability.
• Clinical serum sample analysis showed excellent agreement with ELISA and high recovery rates (>99%).

Conclusions:

• The developed aptamer-ratiometric SERS microfluidic platform offers a rapid and robust solution for simultaneous NGAL and Cys C quantification.
• This technology facilitates early AKI assessment and enables reliable quantitative biomarker analysis at the point-of-care.
• The self-calibrated readout enhances signal accuracy, addressing challenges in decentralized testing.