Macroinitiator triggered polymerization for versatile immunoassay

Abstract

A novel polymerization-based signal amplification strategy by using a dual-functional macroinitiator for ultrasensitive detection of protein was proposed. The macroinitiator composed of streptravidins, initiators, and poly(acrylic acid-co-acrylamide) was endowed with the ability of both molecular recognition and high initiation efficiency. After the immunoreaction and streptravidin–biotin specific identification, the macroinitiators were immobilized on the surface of the substrate and then triggered the generation of an activator by the electron transfer for atom transfer radical polymerization (AGET ATRP) of 2-hydroxyethyl methacrylate (HEMA). The obtained polymers altered the surface reflectivity and opacity at the location of the macroinitiator, which could be easily distinguished by the naked eye within 10 min of polymerization. The numerous hydroxyl groups in the growing polymer chains also led the surface hydrophily change after only 7 min of polymerization. The detection limit of human immunoglobulin G antigen (IgG) by contact angle measurement was 0.13 ng mL⁻¹. The excellent performance of IgG clinical serum sample assay was further examined, showing great potential to detect other biological sample by this sensitive and easy strategy.