Aldehyde N,N-dimethylhydrazone-based fluorescent substrate for peroxidase-mediated assays

Area of Science:

• Biochemistry
• Analytical Chemistry
• Materials Science

Background:

• Peroxidase-based assays are widely used for analyte detection.
• Existing optical peroxidase substrates often suffer from instability issues, including sensitivity to pH, light, and over-oxidation by excess hydrogen peroxide (H₂O₂).

Purpose of the Study:

• To develop a novel fluorescent peroxidase substrate with enhanced stability and quantitative detection capabilities.
• To overcome the limitations of existing substrates, particularly over-oxidation and sensitivity to environmental factors.

Main Methods:

• Synthesis of 2-((6-methoxynaphthalen-2-yl)methylene)-1,1-dimethylhydrazine (MNDH) from a naphthalene-based aldehyde N,N-dimethylhydrazone.
• Evaluation of MNDH's fluorescence response to hydrogen peroxide (H₂O₂) in the presence of horseradish peroxidase (HRP).
• Assessment of MNDH's stability under varying conditions (pH, light, temperature) and in the presence of excess H₂O₂.
• Application of MNDH in an enzyme cascade assay for quantitative glucose detection in human serum.

Main Results:

• MNDH demonstrated quantitative fluorescence changes correlated with H₂O₂ concentration when used with HRP.
• The MNDH/HRP assay exhibited no fluorescence changes due to over-oxidation, even with excess H₂O₂.
• MNDH showed excellent thermal and photostability.
• The assay operated effectively over a broad pH range (acidic to neutral).
• MNDH was successfully employed for quantitative glucose detection in human serum samples.

Conclusions:

• MNDH is a robust and versatile fluorescent substrate for peroxidase-based detection.
• Its stability and resistance to over-oxidation make it superior to many existing substrates.
• MNDH holds significant potential for sensitive and reliable analytical applications, including clinical diagnostics.