A smartphone-assisted one-step bicolor colorimetric detection of glucose in neutral environment based on molecularly imprinted polymer nanozymes

In order to improve the specificity and the peroxidase-like activity of nanozyme at the neutral pH as well as to facilitate the naked-eye visual detection of the analyte concentration, a nanozyme based on molecularly imprinted polymers (MIPNs) for selective and bicolor colorimetric detection of glucose in neutral environment was developed. Compared with free nanozyme, the synthesized MIPNs showed a better catalytic capability, with a catalytic efficiency (kcat/Km) 9.5 times higher than that of free nanozyme. The kinetics experiment showed that the MIPNs demonstrated a fast kinetic feature and the kinetic data fitted a pseudo-first-order model. In practical application, the color of the detection system changed gradually from pink to blue as the glucose concentration increased in a broad linear range from 0 to 3 mM, with a detection limit of 6.22 μM. The colorimetric visualization of glucose concentration was read with a smartphone and no other instrument was needed. Therefore, a manageable and highly efficient method for the MIPNs-catalyzed visualization at the neutral pH and the one-step bicolor visual detection was constructed. This newly established method may also provide a new idea for further development and application of nanozymes.