Effect of Different Coatings on Immobilization of Biomolecules in Brush Polymer Cells

Objective: Biochips with protein and oligonucleotide probes are used in the analysis of samples containing target proteins and nucleic acids. The selection of materials for biochip substrates and the functionalization of the carrier surface are among the key challenges of biochip technology that affect the sensitivity of the assay. Methods: Black polybutylene terephthalate substrates for biochip fabrication were modified by coating them with photoactive polymers: poly(ethylene-co-propylene-co-5-methylene-2-norbornene), acetylcellulose, polyvinyl acetate, and polyvinyl butyral. The polymer coatings were applied by centrifugation followed by drying. The effect of polymer coating on biochip characteristics was investigated. A matrix of hydrophilic cells made of brush polymers with functional epoxy groups, in which DNA probes and human immunoglobulins were immobilized, was obtained by the method of photoinitiated radical polymerization on substrates. The functionality of probes was investigated by hybridization analysis and reaction with specific antibodies. The binding efficiency of probes to molecular targets was evaluated on biochips with different polymer coatings. Results and Discussion: Cells from brush polymers obtained on substrates from polybutylene terephthalate coated with thin films of poly(ethylene-co-propylene-co-5-methylene-2-norbornene), acetylcellulose, polyvinyl acetate and polyvinyl butyral, firmly adhere to the substrate surface, do not break and do not peel off under conditions of DNA hybridization analysis and immunochemical analysis of proteins. The polymer coatings adsorbed insignificantly the analyzed molecular targets, so the result was observed high contrast of fluorescence image of cells after binding of fluorescently labeled molecular targets with molecular probes immobilized in biochip cells. Conclusions: Biochips prepared on polybutylene terephthalate substrates coated with polyvinyl butyral and poly(ethylene-co-propylene-co-5-methylene-2-norbornene) showed the best binding efficiency of immobilized molecular DNA probes and immunoglobulins to responsive molecular targets compared to polyvinyl acetate and acetyl cellulose coatings and are promising for lab-on-a-chip microanalysis technology.