Breaking the Cryogenic Sensing Limitation: Solvent-Microenvironment-Programmed Cold-Adaptable Nanozymes Enable Sensitive Volatile Amine Detection at Low Temperature

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.