초고감도 생체분자 검출을 위한 방사선 그라프트 중합에 의한 불소계 고분자의 기능성 표면 형성에 관한 연구

Abstract

In this research, an innovative and effective method for the surface functionalization of an inert fluoropolymer substrate using radiation grafting was demonstrated for the fabrication of an ultra-highly sensitive fluorescent biosensors. A fluorinated poly(ethylene-co-propylene) (FEP) surface was functionalized by an 150 keV ion implantation followed by the graft polymerization of acrylic acid to generate the high density of the carboxylic acid groups on the implanted surface. The resulting functionalized surface was characterized in terms of the surface density of carboxylic acid, wettability, chemical structure, surface morphology, and chemical composition. These results revealed that poly(acrylic acid)(PAA) was successfully grafted onto the implanted FEP surface and its relative amount depended on the fluence. In order to demonstrate the usefulness of this method for the highly sensitive biosensor, the PAA-grafted FEP films were utilized for the immobilization of a probe DNA for anthrax toxin, followed by hybridization with Cy3-labeled target DNA. Liver cancer-specific alpha-feto-protein (AFP) antigen was also immobilized on the PAA-grafted FEP surfaces. A Texas Red-labeled secondary antibody was reacted with the AFP-specific primary antibody pre-bound to the AFP antigen using a direct immunoassay method. The results revealed that the fluorescence intensity depended mainly on the concentration of the target DNA hybridized to the probe DNA and the AFP antigen immobilized on the FEP films. The lowest detectable concentrations of the target DNA and the AFP antigen were 10 fg/ml (1.15 fM) and 10 pg/ml (140 fM), respectively, with the FEP film prepared at a fluence of 3 x 1014 ions/cm2.