Nanozymes, with recognized superiorities over natural enzymes, hold enormous potential in biochemical analysis, while their poor catalytic efficiency and kinetics, particularly under low-temperature conditions, severely limit practical use in cryogenic scenarios. To break the low-temperature sensing limitation, here we propose a solvent-microenvironment-programmed manganese-coordinated polyphosphate (Mn(DTPMP)) with the cold-adaptable oxidase-mimetic feature to achieve the sensitive detection of volatile amines (VAs) in food cold-chain logistics. By employing different solvents during hydrothermal synthesis, both the physical structure and surface chemistry of Mn(DTPMP) were subtly modulated, which contributed to the oxidase-mimicking catalytic characteristics jointly. The nanozyme exhibited robust performance across a temperature range from near-zero to physiological, and such an exceptional feature was proved to originate from the synergistic interplays of unique elemental composition, valence state distribution, extremely low activation energy barrier, and high-spin electron configuration. Leveraging the cold-adaptable nanozyme, a sensitive colorimetric approach was established and validated for accurately monitoring VAs in low-temperature environments, with a detection limit as low as 0.17 ppm. By breaking the temperature barrier, the paradigm of developing high-activity cold-adaptable nanozymes extends their application frontiers in cryogenic measurements. Besides, our study offers fundamental insights into the solvent-microenvironment-mediated regulation of nanozymes and deepens the mechanism understanding of their cold-adaptable effect, both of which can inspire designing advanced enzyme mimics for broader cryogenic science including but not limited to analytical sensing.
Chen et al. (Tue,) studied this question.