A fluorimetric test strip with suppressed "Coffee Ring Effect" for selective mercury ion analysis

Area of Science:

• Analytical Chemistry
• Materials Science
• Nanotechnology

Background:

• Test strips are limited to qualitative analysis due to the "Coffee Ring Effect" (CRE), causing uneven probe distribution.
• CRE leads to poor reproducibility and sensitivity in current test strip technologies.
• Developing methods to suppress CRE is crucial for advancing quantitative test strip analysis.

Purpose of the Study:

• To fabricate a fluorescent test strip with suppressed CRE for enhanced probe deposition.
• To enable sensitive and quantitative detection of target analytes using the developed test strip.
• To demonstrate the potential of this fabrication protocol for point-of-care analytical applications.

Main Methods:

• Fabrication of a fluorescent test strip using silver nanocluster (AgNC) probes coated with gelatin (Gel).
• Suppression of CRE achieved through vacuum-aided fast lyophilization.
• Quantitative analysis of Hg²⁺ ions using the AgNC-based fluorescent test strip.

Main Results:

• Uniform and stable deposition of AgNC probes with high loading capacity was achieved.
• The test strip demonstrated specific responses to Hg²⁺ ions.
• Sensitive and quantitative detection of Hg²⁺ ions was achieved in linear concentration ranges from 0.20 to 50000 nM, with a limit of detection of 0.10 nM.

Conclusions:

• The developed fabrication protocol effectively suppresses CRE, enabling uniform AgNC probe distribution.
• The fluorescent test strip offers advantages like rapid preparation, high biocompatibility, and cost-effectiveness.
• This method holds promise for designing various test strip-based devices for environmental monitoring, food quality, and clinical diagnostics.