A highly selective biosensor with nanomolar sensitivity based on cytokinin dehydrogenase

Area of Science:

• Biotechnology
• Analytical Chemistry
• Plant Science

Background:

• Cytokinins are crucial plant hormones regulating growth and development.
• Accurate and real-time measurement of cytokinins is essential for plant science research.
• Existing methods for cytokinin detection can be time-consuming and lack sensitivity.

Purpose of the Study:

• To develop a sensitive and selective microbiosensor for the real-time determination of cytokinins.
• To utilize cytokinin dehydrogenase (CKX) enzyme for specific hormone detection.
• To enable rapid analysis of cytokinins in biological samples.

Main Methods:

• Immobilization of Zea mays cytokinin dehydrogenase (ZmCKX1) on a Pt microelectrode.
• Electrodeposition of a silica gel film and functionalization with DCPIP mediator.
• Development of a microbiosensor for selective oxidative cleavage of cytokinin N6- side chains.

Main Results:

• The microbiosensor achieved a fast response time (<10 s) and a low detection limit (3.9 nM) for N6-(Δ2-isopentenyl) adenine (iP).
• Demonstrated high sensitivity (603.3 µAmM⁻¹cm⁻²) and a wide linear dynamic range (10 nM to 10 µM) for iP.
• Exhibited excellent selectivity for aliphatic cytokinins and ribosides, with poor substrate activity for aromatic cytokinins and glucosides.
• Successfully quantified low nanomolar cytokinin concentrations in tomato xylem sap.

Conclusions:

• The developed ZmCKX1-based microbiosensor provides a robust platform for rapid and selective cytokinin quantification.
• This technology offers significant advantages for real-time monitoring of plant hormone levels in various matrices.
• The microbiosensor's stability and sensitivity make it a valuable tool for plant physiology and agricultural research.