Turn-on fluorescence sensor for the detection of heparin based on rhodamine B-modified polyethyleneimine–graphene oxide complex

Abstract

Rhodamine B modified Polyethyleneimine (PEI) (called RB–PEI) with strong fluorescence intensity was synthesized, which contained high positively charged amine groups. The fluorescence intensity of RB–PEI can be quenched by graphene oxide (GO). The high efficiency of the quenching was caused by the non-covalent binding of RB–PEI to the GO surface by electrostatic and π–π interactions, forming a RB–PEI/GO complex. However, adding heparin caused intense fluorescence to be recovered, and this was caused by the anionic heparin removing the RB–PEI from the GO surface, forming a fluorescent RB–PEI/heparin complex. Under optimal conditions, the change in the fluorescence intensity when heparin was added was proportional to the heparin concentration over the range 0.09–0.9UmL−1. The detection limit for heparin was 0.00132UmL−1, which was lower than that has been achieved using other methods. This approach offers a new quantitative method for determining heparin.