Nanochemistry and biotechnology

Cholesteric liquid crystal and amino acid as sensitive element
for optical sensor.
Khomyak S.V.1, Havryliak V.V.1, Prystay T.V.2, Sushynskyi O.Y.2, Petrina R.O.1
1 Lviv Polytechnic National University, Department of Technology of Biologically Active Substances, Pharmacy and Biotechnology, 12 Bandera str., Lviv, Ukraine.
E-mail: semen.v.khomyak@lpnu.ua
2 Lviv Polytechnic National University, Department of Electronic Devices, 
12 Bandera str, Lviv-79013, Ukraine.

Nowadays much attention is devoted to the development of nanoparticles which widely used in medicine, pharmacy and biotechnology as biosensors, medical devices, diagnostic chips, etc. The natural structures, such as proteins, antioxidants, amino acids have advantages in application due to their low toxicity, high efficiency, low number of side effects, and high activity in the regulation of metabolic processes in the body. At present, known nanosystems based on amino acids and proteins are characterized by great opportunities for nanocomposite producing [1]. As model proteins, we have used keratins derived from human hair. These proteins are widely used for tissue engineering, nanocomposites, and others. Keratins are a mixture of proteins with different molecular weights. The molecular weight of the main two fractions varies in a range from 45 to 65 kDa.
A sensitive element of an optical sensor based on a liquid crystal and amino acids is developed. A multi-component liquid crystal consists of cholesteric BLO-62 and nematic 5СВ part and have minimum optical transmission at 520 nm [2]. Next, the amino acids, for example methionine, asparagine, leucine, valine, glicine were added as a nanoparticle dopant into the cholesteric-nematic mixture. Obtained sensitive element is characterized by more chirality and polarity of spiral structure and redshift of minimum optical transmittance to the long-wavelength region. Addition both the solution and the crystals of protein to the sensitive element of optical sensor is accompanied by a shift of the minimum transmittance to the short-wave region. These results have the prospect of identification of amino acids and proteins in biological objects.

1.	Chekman I. S. Nanoscience: prospects of scientific investigations // Nauka ta innovatsiia.- 2009.- 5, N 3.- P. 89–93.
2.	Vistak M.V., Dmytrakh V.E., Mykytyuk Z.M., Petryshak V.S., Horbenko Y.Y. A liquid crystal-based sensitive element for optical sensors of cholesterol // Functional Materials. - 2017.- 24, N 4, - P. 687-691.