Semi-enclosed paper sensor for highly sensitive and selective detection of proline

Area of Science:

• Analytical Chemistry
• Biochemistry
• Materials Science

Background:

• Proline is a key stress biomarker in plants and an important amino acid in food and wine.
• Accurate quantification of proline is crucial for agriculture, food, and wine industries.
• Existing methods for proline detection can be complex and time-consuming.

Purpose of the Study:

• To develop a sensitive and accurate microfluidic paper-based analytical device (μPAD) for proline detection.
• To utilize isatin-conjugated chitosan as a specific colorimetric reagent for enhanced proline quantification.
• To establish a smartphone-based imaging platform for on-site proline analysis.

Main Methods:

• Fabrication of semi-enclosed, leak-proof μPADs modified with isatin-conjugated chitosan.
• Colorimetric detection of proline based on the specific interaction with isatin.
• Smartphone-based image capture using a 3D-printed imaging box for uniform illumination and positioning.
• Evaluation of proline content in Arabidopsis plants under water stress.

Main Results:

• The developed μPAD platform demonstrated enhanced color signal intensity and accuracy.
• The method achieved a comparable limit of detection (23.75 μM) with an enhanced detection range (∼7 fold) compared to previous platforms.
• Optimized reaction conditions required reduced temperature and time.
• Successfully evaluated proline levels in water-stressed Arabidopsis plants.

Conclusions:

• The isatin-conjugated chitosan modified μPAD offers a sensitive, rapid, and cost-effective method for proline quantification.
• The smartphone-based imaging system enhances the accuracy and accessibility of the assay.
• This paper-based platform holds significant potential for on-site evaluation of plant stress and proline content in various industries.