Logic-Gated NIR-IIb Theranostic Nanozymes for Longitudinal Quantitative Assessment of In-Situ Cytotoxic T Lymphocytes

The efficacy of cancer immunotherapy critically hinges on the infiltration density and functional activity of cytotoxicT lymphocytes (CTLs). Current technologies lack the capacity for noninvasive in situ and quantitative detection of CTLs, presenting a major barrier to assessing these key CTL-associated metrics. Here, we report a NIR-IIb theranostic nanozyme (CMQG) based on an "AND" logic gate design for the longitudinal quantitative assessment of in-situ CTLs. CMQG enables synchronous acquisition of the infiltration visualization and functional status of CTLs via spatial targeting and self-calibrated ratiometric fluorescence imaging. Concurrently, its inherent photothermal property and catalase-like activity synergistically modulate the recruitment and activation of CTLs. The "AND" Boolean operation enables noninvasive detection of these longitudinal changes by outputting a quantitative metric for CTL relative density, which shows a robust correlation with gold-standard flow cytometry (R² = 0.9896). Notably, a 4.57-fold longitudinal change in in-situ CTLs was noninvasively quantified through the integration of the "AND" logic gate design with the intrinsic properties of CMQG. This theranostic paradigm offers a transformative potential for advancing precision immuno-oncology.