It is challenging to capture glycoprotein from complicated samples with both high specificity and high recovery. Herein, we synthesized temperature-responsive poly (N-isopropylacrylamide-4-vinylbenzeneboronic acid) (PNIPAM-VPBA) microgels having enhanced affinity capability towards glycoprotein, resulting signal amplification in colorimetric analysis subsequently. Through temperature control, the target glycoprotein can be captured and released by the reported microgels unbiasedly. The microgels fabricated were characterized in terms of particle size, phase transition temperature, and toxicity. It was revealed that obvious changes in the particle diameter ranged from 600 to 323 nm between 25 °C and 55 °C, the volume transition temperature was close to human physiological temperature, and low toxicity towards HeLa cells after 24 h incubation. Using glucose oxidase as a model target, the microgels were applied as adsorbent materials for preconcentration of glucose oxidase, resulting 22-fold signal enhancement and a limit of detection (LOD) as low as 16.7 U/L. In beer sample analysis, satisfied recoveries of 78.7%-101.6% with the relative standard deviations (RSDs) less than 7.2% was observed. Subsequently, the microgels were combined with enzyme-linked immunosorbent assay (ELISA) for alpha fetoprotein (AFP) determination, by immobilizing horseradish peroxidase (HRP) and anti-AFP antibodies on the surface of microgels. A meaningful low concentration range of 2.5 × 10-2 to 1.0 µg/L was obtained for AFP detection using the microgels based colorimetric method with a LOD of 8.4 ng/L. In human serum sample analysis, good accuracy was achieved from method comparing with commercial ELISA kit, satisfied recoveries of 86.1%-96.4% with the RSDs less than 6.0% was observed. The proposed PNIPAM-VPBA microgels have great potential applications in the fields of food and clinical analysis.
A controlled recognizing and releasing glycoprotein based on temperature-responsive phenylboronic microgels for colorimetric analysis of complex samples