Label-free peptide-based biosensor for express detection of protein markers of acute cardiovascular conditions in biological fluids

Acute cardiovascular conditions require prompt assistance, which depends on a timely and accurate diagnosis. This could be achieved by using biosensor systems based on peptide aptamers capable of selectively binding protein markers of diseases. In this work, a label-free biosensor system based on fluorimetric registration of the formation of a "peptide aptamer - target protein" complex is considered. It comprises a microfluidic subsystem integrated with arrays of sites with immobilized peptide aptamers, coupled with optical detection system. The clinical sample of the whole blood is loaded into the inlet basin, where the cells are separated and plasma flows into the microfluidic channel for analysis. Peptide aptamers were created using the molecular complement search technique based on the search for systems of conjugated ion-hydrogen bonds in the three-dimensional structures of target proteins. The technology for manufacturing a microfluidic chip is a combination of thick-film and photolithography technologies based on the SU-8 photoresist, for which the relief and surface morphology have been studied. The composition of the biochip layers is selected in such a way that ultraviolet light with a wavelength of 280 nm passes through inlet window, excites fluorescence inside the channel, which passes through the glass window, which absorbs UV-light. This wavelength accounts for the maximum absorption of aromatic amino acids - tyrosine and tryptophan. In this case, one of the last layers is a luminophore layer for re-emission of protein fluorescence as a visible light. The reading platform includes a 280nm LED, a video sensor, tooling, 3D-printed PLA tooling, and software for processing and analyzing the received signal.