A highly sensitive fluorescence sensor based on lucigenin/chitosan/SiO₂ composite nanoparticles for microRNA...

Area of Science:

• Nanomaterials Science
• Biomedical Engineering
• Analytical Chemistry

Background:

• Developing sensitive and selective methods for miRNA detection is crucial for early disease diagnosis.
• Chitosan-modified silica nanoparticles offer unique properties for biosensing applications.
• Lucigenin as a fluorescent dye can be incorporated into nanomaterials for signal generation.

Purpose of the Study:

• To develop a convenient reverse-phase microemulsion method for synthesizing chitosan/SiO2 nanoparticles.
• To establish a label-free, enzyme-free fluorescence analysis method for direct detection of let-7a miRNA in human gastric cancer cells.
• To enhance the fluorescence quantum yield and improve detection sensitivity using chitosan modification.

Main Methods:

• Synthesis of SiO2 nanoparticles via a reverse-phase microemulsion method.
• Incorporation of chitosan and lucigenin during SiO2 nanoparticle formation.
• Utilizing the differential adsorption of single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA) onto positively charged nanoparticles to differentiate fluorescence intensity.
• Direct detection of let-7a miRNA in human gastric cancer cell samples.

Main Results:

• Chitosan addition resulted in porous SiO2 nanoparticles with increased lucigenin incorporation and enhanced fluorescence quantum yield.
• A clear discrimination in fluorescence intensity was observed between ssDNA and dsDNA/miRNA.
• A good linear relationship was established between fluorescence intensity and target miRNA concentration.
• The method demonstrated high sensitivity and selectivity, with a detection limit of 10 fM (S/N = 3).

Conclusions:

• The developed lucigenin/chitosan/SiO2 composite nanoparticles serve as an effective DNA hybrid indicator for miRNA detection.
• The proposed fluorescence analysis method is sensitive, selective, label-free, enzyme-free, and cost-effective.
• This method holds promise for the direct and early detection of let-7a miRNA in clinical samples, aiding in gastric cancer diagnosis.