Cascade controlled release system based on pH-responsive ZIF-8 capsule and enzyme-responsive hyaluronic acid hydrogel for tumor marker detection using electro-readout-mode

Abstract

A novel cascade controlled release system based pH-responsive ZIF-8 capsule and enzyme-responsive hyaluronic acid hydrogel was proposed for the electrochemical detection of tumor marker. Glucose in tube as “original trigger” can be effectively transformed to provide numerous protons under the catalysis of glucose oxidase modified on immune magnetic beads to glucose. Being affected by acidic condition, hyaluronidase encapsulated in ZIF-8 was released. After the addition of hyaluronidase on electrode covered with hyaluronic acid hydrogel containing methylene blue molecules, the hydrogel was sequentially disintegrated, resulting in the release of methylene blue. The whole process from acidic stimulation to the transmission of hyaluronidase and finally the release of methylene blue avoided many problems derived from tedious modification of electrode surface in traditional electrochemical immunoassay and made this immunoassay exhibit an excellent analytical performance. Under the optimal conditions, the proposed method exhibits an excellent analytical performance with a wide range from 1.000 × 10−3-1.000 × 102 ng mL−1 and ultralow detection limit of 37.27 fg mL−1 toward prostate specific antigen (as a model analyte). This study opens new perspective for the exploration of controlled release system in electrochemical sensing applications.