Nanobiotechnology for health-care

Optimization of a nanocomposite membrane based on immobilized L-lactate dehydrogenase as a part of biosensor for non-invasive determination of lactate in sweat
Biloivan O., Vorobeyenko O., Korpan Ya.
Department of Biomolecular Electronics, Institute of Molecular Biology and Genetics, Natl. Acad. of Sci. of Ukraine. Zabolotnogo street, 150, Kiev-03680, Ukraine. 
E-mail: o.a.biloivan@edu.imbg.org.ua

Analysis of lactate concentration is important for monitoring the physical state of athletes. The development of an epidermal smart sensor for the determination of lactate in sweat will allow for such monitoring without the need for blood sampling. The basis of the qualitative work of the biosensor system is a stable, reproducible and highly effective enzyme matrix.
The electrochemical analysis of L-lactate was provided by the determination of reduced nicotinamide adenine dinucleotide (NADH) as a product of enzyme conversion with L-lactate dehydrogenase (LDH) and coenzyme NAD +. For this, the surface of the printed carbon electrode was modified with a tri-layer structure, which consisted of a layer of N-graphene, an immobilized LDH-NAD+ complex, and an additional membrane based on m-phenylenediamine. Modification of the surface of the working electrode (DropSens C110) was performed by drop method with a mixture of N-graphene with chitosan. The LDH layer was formed by covalently binding in glutaraldehyde vapors to a BSA gel. An additional m-phenylenediamine membrane was applied by electropolymerization.
Developed model of the biosensor allows of L-lactate analysis in the range of concentrations of 1-8 mM with a sensitivity of 0.145 µA / mm and a detection limit of 50 µM. The influence of interfering substances on the results of lactate measurement is insignificant The operational stability of the biosensor was found as 10 measurements of lactate and stability during storage at 40C in dry form - during the month

Acknowledgment. 
This work was supported by the State Budget Program "Support for the Development of Priority Areas of Scientific Research" (Code: 6541230) through a program of National Academy of Sciences of Ukraine “Smart sensor devices of a new generation based on modern materials and technologies”.