Activators generated electron transfer for atom transfer radical polymerization for immunosensing

A novel and ultrasensitive immunosensing strategy based on activators generated electron transfer for atom transfer radical polymerization (AGET ATRP) in combination with flow injection chemiluminescent (CL) and electrochemical detection was proposed. The initiator-conjugated polyclone PSA antibodies (Ab2*), prepared by coupling of N-hydroxysuccinmidyl bromoisobutyrate (initiator) with polyclone PSA antibodies (Ab2), were immobilized on the substrate surface through sandwiched immunoreactions to trigger polymerization. AGET ATRP is used for local accumulation of glycidyl methacrylate (GMA) monomers. Horseradish peroxidase (HRP) was chosen as signal species for its well-characterized chemiluminescent and electrochemical behavior, strong enzyme activity, good solubility and ease in coupling. Growth of long chain polymeric materials provided excess epoxy groups for HRP coupling, which in turn significantly increased the loading of signal molecules and enhanced the chemiluminescent and electrochemical readouts. With the proposed strategy, a detection limit of 4.0 and 1.3 pg mL−1 was obtained for flow injection chemiluminescent and electrocatalytic measurements, respectively. A more than 13- and 14-fold enhancement in the chemiluminescent intensity and electrocatalytic current was achieved comparing to the traditional sandwiched immunoassays using HRP-conjugated antibody directly. The proposed method exhibited an efficient amplification performance for immunosensing. This paved a new way for ultrasensitive detection of cancer biomarkers.