Clicking Fluorometric Probes on Micropatterned Glass Microfiber Filters for ppb-Level Copper Quantitation

Area of Science:

• Analytical Chemistry
• Materials Science
• Biomedical Engineering

Background:

• Microfluidic paper-based analytical devices (μPADs) offer a low-cost platform for diagnostics.
• Surface modification is crucial for immobilizing probes and controlling fluid flow in μPADs.
• Traditional fabrication methods can be complex and time-consuming.

Purpose of the Study:

• To develop a facile and efficient method for fabricating μPADs.
• To enable ultrasensitive fluorometric assays using covalent modification and benchtop patterning.
• To demonstrate the application of these μPADs for copper detection.

Main Methods:

• Covalent surface modification of glass microfiber filters (GMFs) using click chemistry (CuAAC).
• Benchtop machine-cutting of GMFs to create patterned assay zones.
• Immobilization of fluorometric probes (A-7-HC) and superhydrophobic treatment (OTMS).
• Smartphone imaging for quantitative fluorometric detection of copper standards.

Main Results:

• Fabrication of distinct and uniform assay sites on GMFs without coffee-ring effect.
• Achieved impressive limits of detection (9.2 ± 0.8 ppb) for copper.
• Validated results with atomic absorption spectroscopy for commercial copper supplements.

Conclusions:

• The combination of covalent modification and benchtop patterning provides a flexible and effective approach for μPAD fabrication.
• This method enables ultrasensitive quantitative fluorometric assays.
• The developed μPADs show significant potential for various analytical applications.