Target-responsive DNA hydrogel for non-enzymatic and visual detection of glucose.

We have successfully developed a target-responsive aptamer cross-linked hydrogel for the visual detection of glucose, an important biomedical analyte. In this work, the glucose-responsive hydrogel was prepared using the target aptamer and its two short complementary DNA strands grafted onto a linear polyacrylamide chain as cross-linkers. Gold nanoparticles (AuNPs) modified with thiol-PEG were encapsulated in the gel and used as the output signal for visible detection. The complex of glucose and its ligand of boronic acid derivatives (Shinkai's receptor) can bind with the aptamer to disrupt the hydrogel, leading to the release of AuNPs with a distinct red colour in the supernatant. By this method glucose can be detected with the naked eye, and the sensor has a detection limit of 0.44 mM in buffer with the help of UV-Vis spectrophotometry. Furthermore, glucose spiked in 50% urine and 30% serum could also be detected respectively with the naked eye, and glucose was quantitatively detected in 50% urine. The hydrogel system provides a non-enzymatic and visual method for glucose detection, and offers promising applications in biotechnology and biomedicine.