Generation of Active Amino Groups on the Surface of a Polyethylene Terephthalate Film and Their Quantitative Evaluation

Objective: Polyethylene terephthalate (PET) is thermally stable, biocompatible, transparent in visible and near-infrared light. The study of grafting conditions and the distribution of reactive amino groups on the PET surface without affecting the polymer array makes it possible to change the surface properties in a directed manner. Methods: A method for obtaining active amino groups on the surface of polyethylene terephthalate (PET) substrate by reaction with ethylenediamine was developed. A method for quantitative estimation of the concentration and distribution of chemically accessible amino groups on the surface of PET substrate using cyanine dye Cy5 and digital fluorescence microscopy was developed. Results and Discussion: The PET surface during chemical modification remains without visible damage up to the concentration of amino groups 8 pmol/cm², while surface degradation is observed at higher concentrations. Chemically available amino groups capable of covalently binding to Cy5 dye are distributed unevenly, which is probably due to the presence of amorphous and crystalline areas on the surface of PET substrates. Amino groups can be used for further chemical modification of the PET surface, grafting of various functional groups, and covalent binding to biomolecules, which opens up prospects for the wide use of inexpensive PET as functional substrates in biochips, biosensors, lab-on-a-chip devices, and other biotechnological applications.