Portable multi-amplified temperature sensing for tumor exosomes based on MnO2/IR780 nanozyme with high photothermal effect and oxidase-like activity

Efficient determination of tumor exosomes using portable devices is crucial for the establishment of facile and convenient early cancer diagnostic methods. However, it is still challenging to effectively amplify the detection signal to achieve tumor exosomes detection with high sensitivity by portable devices. To address this issue, we developed a portable multi-amplified temperature sensing strategy for highly sensitive detecting tumor exosomes based on multifunctional manganese dioxide/IR780 nanosheets (MnO₂/IR780 NSs) nanozyme with high oxidase-like activity and enhanced photothermal performance. Inspiringly, MnO₂/IR780 NSs were synthesized via a facile one-step method with mild experimental conditions, which not only exhibited a stronger photothermal effect than that of MnO₂ but also showed excellent oxidase-like activity that can catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) to generate TMB oxide (oxTMB) with a robust photothermal property, thus conjoining with MnO₂/IR780 NSs to further enhance the temperature signal. The present assay enables highly sensitive determination of tumor exosomes with the detection limit down to 5.1 × 10³ particles/mL, which was comparable or superior to those of the most previously reported sensors. Furthermore, detection of tumor exosomes spiked in biological samples was successfully realized. More importantly, our method showed the recommendable portability, robust applicability, and easy manipulation. By taking advantages of these features, this high-performance photothermal sensor offered a promising alternative means for nondestructive early cancer diagnosis and treatment efficacy evaluation.