Core/shell structure photonic crystal microneedle patch for painless, in situ and visualization in glucose monitoring

Diabetes is a global public health problem that is easy to ignore and difficult to detect early. Here we introduce a photonic crystal hydrogels microneedle (PCHMN) patch with a core-shell structure for painless, in-situ and visual monitoring of glucose concentration. The microneedles (MN) have a high specific surface area (tip height: 1600 μm, base width: 500 μm), high mechanical toughness (tensile strength:10.49 MPa, breaking elongation: 11%), and high load (0.09 N per needle) to achieve painless penetration of the skin stratum corneum. Based on the deprotonation of the carboxyl group of the polymer after hydrolysis, the microneedle patch is responsive to pH and achieves a response to glucose due to the specific binding of the phenylboronic acid group to the glucose molecule in the polymer chain segment, and performs well in the detection application in mice. Because these response processes can lead to changes in the swelling degree and volume of microneedles, and then produce changes in structural color and reflection spectrum, so as to realize the monitoring of the above detection substances. These characteristics indicate that the microneedle patch prepared by us can be customized to design various wearable sensing devices for painless and in situ monitoring of various biomarkers in tissue fluid by simply changing the types of response groups.