Nanochemistry and biotechnology
Electrochemical determination of L-lactate based on nanostructured printed electrodes
Biloivan O., Boichuk Yu., Korpan Ya.

1Department 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

Despite the fact that there are numerous biosensors for the determination of lactate, the researchers focus on the creation of supersonic biosensors, non-invasive or semi-invasive, which can fulfill the requirement for continuous monitoring of lactate. This type of sensor encounters the need to solve a number of issues, namely miniaturization and analysis in insignificant sample sizes, the impossibility of sampling for measurement, slow dynamic response and some technical problems. Nevertheless, with the advent of nanotechnologies, progress can be made in the development of semi-invasive, finally, non-invasive touch-sensitive devices for commercialization.
Electrochemical analysis of L-lactate is based on the detection of reduced nicotinamide adenine dinucleotide (NADH) as a product of enzyme transformation involving lactate dehydrogenase (LDH). The work included the development of a highly efficient nanocomposite electrode for monitoring NADH and optimization of the procedure of L-lactate analysis in the presence of LDH and NAD+. The screen-printed carbon electrodes (SPCEs) modified with N-graphene (NG), detonation nanodiamonds (dNDs) and polymer nanocomposite films were used. The methods of cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and amperometry were used to investigate the electrochemical properties of different modifications of SPCEs. L-lactate determination using the developed electrodes was shown to be possible in the concentration range of 1-50 mM. The L-lactate assay in 50µl probe was optimized and it employed CV (0.3V, 75mV/s) in 0.1 M phosphate buffer, pH 7.5 with 10 mM NAD+ and LDH (0.05 U/ml).  At the next stage of the research the modified electrodes will be applied to create the appropriate biosensors with the immobilized enzyme matrix.

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”.