Immobilization of antibody conjugated ZnS quantum dots onto poly(2,6-dimethyl-1,4-phenylene oxide) nanofibers with Poly(N-isopropylacrylamide) grafts as reversibly fluorescence immunoassay

In this study a reversibly fluorescence immunoassay was prepared through grafting, using hydrogen bonding, of an antibody-conjugated ZnS quantum dots (ZQD-antiHA) onto an electrospun poly (2,6-dimethyl-1,4-phenylene oxide) (PPO) fibrous mats (EPFM) with poly (n-isopropylacrylamide) (PNIPAAm) grafts. The PPO was first electrospun into a fibrous mat, then brominated and reacted with NaN3 to generate the azido-terminated EPFMs. A propargyl-terminated poly (n-isopropylacrylamide) (PNIPAAm) was synthesized and grafted onto the azido-terminated EPFMs. ZQDs were conjugated by antibodies (antiHA) to adsorb onto the PNIPAAm grafts of EPFMs with hydrogen bonding. Because of the stronger interaction between antigen (HA) and antibody (antiHA), the hydrogen bonding was blocked due to the introduction of the antigen which resulted in the desorption the ZQDs from the EPFMs. The blue fluorescence of the PNIPAAm-grafted EPFMs with antibody-conjugated ZQDs was disappeared while immersing in the solution of antigen. The 3.82 mg/m2 of ZQDs on the PNIPAAm grafts EPFMs significantly reduced to 0.22 mg/m2 after the immersion of the antigen solution which verified the transference of the ZQDs from EPFMs to the solution. The behavior of adsorption and desorption of the ZQDs was reversible up to five cycles. The revisable fluorescence immunoassay of EPFMs with PNIPAAm grafts experimentally exhibited a high potential in a simple setup for biosensing with its unique sensitivity and selectivity.