Pixelated colorimetric nucleic acid assay.

Area of Science:

• Biochemistry
• Analytical Chemistry
• Materials Science

Background:

• Conjugated polyelectrolytes (CPEs) are effective reporters in colorimetric nucleic acid assays.
• Detecting low concentrations of nucleic acids with the naked eye using CPEs is challenging due to subtle colorimetric responses.
• Existing methods for interpreting colorimetric data, like RGB analysis, can introduce errors.

Purpose of the Study:

• To develop a pixelated analysis approach for sensitive and accurate quantification of nucleic acids using CPEs.
• To enable naked-eye detection of nucleic acids down to 1 nM in complex samples like plasma.
• To validate the use of a smartphone for point-of-care nucleic acid testing.

Main Methods:

• Utilized a cationic CPE reporter (poly[N,N,N-triethyl-3-((4-methylthiophen-3-yl)oxy)propan-1-aminium bromide]) on a polyvinylidene fluoride (PVDF) membrane.
• Employed a detection strategy based on conformational transitions of nucleic acid-CPE complexes (duplexes and triplexes) leading to distinct colorimetric changes.
• Developed a smartphone application to capture and digitize colorimetric responses from individual pixels, analyzed by a custom algorithm.

Main Results:

• Achieved correlation between CPE colorimetric responses and nucleic acid concentrations down to 1 nM in plasma samples.
• Demonstrated precise quantification of nucleic acid concentrations, overcoming limitations of conventional interpretation methods.
• Showcased the reliability of the pixelated approach for accurate analysis in complex biological matrices.

Conclusions:

• A smartphone-based pixelated analysis method provides accurate and sensitive colorimetric detection of nucleic acids.
• This approach facilitates point-of-care testing in complex samples without specialized equipment.
• The developed strategy enhances the utility of CPEs for accessible nucleic acid diagnostics.