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Published on: September 19, 2018
A pH Indicator-linked Immunosorbent assay following direct amplification strategy for colorimetric detection of
Fengying Shao1, Lei Jiao1, Luyang Miao1
1School of Chemistry and Chemical Engineering, and School of Biological Science and Technology, University of Jinan, Jinan 250022, China.
Insights
A novel pH indicator-linked immunosorbent assay (PILISA) utilizes carbon nitride nanosheets for sensitive colorimetric detection of protein biomarkers. This enzyme-free method offers a robust platform for clinical diagnostics.
Area of Science:
- Biomarker Detection
- Nanomaterials Science
- Analytical Chemistry
Background:
- Colorimetric assays are crucial for detecting disease markers.
- Existing methods often require enzymes, increasing complexity and cost.
- There is a need for sensitive, enzyme-free diagnostic tools.
Purpose of the Study:
- To develop a novel, enzyme-free colorimetric assay for protein biomarker detection.
- To utilize pH indicator molecules and carbon nitride nanosheets for signal enhancement.
- To achieve high sensitivity (pg/mL) for practical clinical applications.
Main Methods:
- Developed a pH indicator-linked immunosorbent assay (PILISA) using carbon nitride nanosheets as signal enhancers.
- Loaded pH indicator molecules (phenolphthalein) onto carbon nitride nanosheets.
- Triggered color change via alkali solution (AS) release of pH indicator molecules upon secondary antibody binding.
- Measured absorbance of the pH indicator for quantitative analysis.
Main Results:
- Achieved picogram per milliliter (pg/mL) sensitivity for protein biomarker detection.
- Demonstrated that absorbance intensity is proportional to biomarker concentration.
- Highlighted the role of ultrathin carbon nitride nanosheets in adsorbing and releasing pH indicators effectively.
- Showcased an enzyme-free approach with a stable and low-cost colorimetric detection mechanism.
Conclusions:
- The developed PILISA is a sensitive and robust method for colorimetric protein biomarker detection.
- The enzyme-free nature and use of nanomaterials offer advantages for clinical applications.
- This innovative assay holds significant potential for practical use in diagnostics.
Abstract:
A new pH indicator-linked immunosorbent assay (PILISA) reached pg/mL sensitivity based on pH indicator molecules loaded carbon nitride nanosheets as signal enhancer has been developed for colorimetric detection of protein biomarkers. As the secondary antibody binds to the carbon nitride nanosheets, the carbon nitride nanosheets and pH indicator complex as the signal amplification platform for colour change by detecting absorbance of pH indicator. The colour change was resulted from the releasing of pH indicator molecules from carbon nitride nanosheets triggered by alkali solution (AS). In this novel PILISA, the intensity absorbance of pH indicator is proportional to the concentration of the disease marker. The outstanding detection performance of the PILISA can be attributed to the following reasons: (1) ultrathin carbon nitride nanosheets with a larger surface area could adsorb abundant phenolphthalein (PP) molecules through hydrophobic interactions as well as the resulted PP anions can be free easily released into aqueous solution, leading to an obvious allochroic response; (2) the signal intensity is precisely determined by the amount of PP molecules loading onto the carbon nitride nanosheets surface, which ensures simple, low-cost and stable colorimetric detection. As expected, this new PILISA method offered an enzyme-free approach followed enzyme-linked immunosorbent assay format, which showed great promising potential as an innovative robust assay method for practical clinical applications.
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