Accurate and Real-Time Detection Method for the Exothermic Behavior of Enzymatic Nano-Microregions Using Temperature-Sensitive Amino-AgInS₂ Quantum Dots

The thermal behavior of enzymes in nanoscale is of great significance to life phenomena. This nonequilibrium state real-time thermal behavior of enzymes at nanoscale cannot be accurately detected by existing methods. Herein, a novel method is developed for the detection of this thermal behavior. The enzyme-quantum dot (QD) conjugates can be obtained by chemically grafting temperature-sensitive amino-AgInS₂ QDs to the enzyme, where the QDs act as nanothermometers with a sensitivity of −2.82% °C⁻¹. Detecting the photoluminescence intensity changes of the enzyme-QD conjugates, the real-time thermal behavior of enzymes can be obtained. The enzyme-QD conjugates show a temperature difference as high as 6 °C above ambient temperature in nano-microregions with good reproducibility (maximum error of 4%) during catalysis, while solution temperature hardly changed. This method has a temperature resolution of ≈0.5 °C with a detection limit of 0.02 mg mL⁻¹ of enzyme, and spatially ensured that the amino-AgInS₂ QDs are quantitatively bound to the enzyme; thus, it can accurately detect the exothermic behavior of the enzyme and can be extended to other organisms’ detection. This method has high sensitivity, good stability, and reliability, indicating its great potential application in investigating the thermal behavior of organisms in nanoscale and related life phenomena.