Quantitative Visualization of Intracellular Nanometabolism Using Peak-Shifted Dual-State Emissive FRET Nanoprobes

Many nanoscale materials, ranging from environmental particulates to carrier-free nanomedicine platforms, enter the human body, yet their metabolic fates remain poorly understood. This process involves complex physical changes and molecular transformations within lysosomes; however, the particle-to-molecule transition-defined here as "nanometabolism"-has remained difficult to quantify due to intrinsic limitations of nanoscale bioimaging. To circumvent the fluorescence quenching of conventional fluorophores and the challenges of observing nanoscale dynamics, peak-shifted, dual-state emissive nanoprobes composed entirely of donor-acceptor bithiophene dyes are introduced here. This approach establishes a highly adaptable design strategy for constructing heterogeneous organic nanoparticles templated by these molecular metrics. These molecular probes generate bright, ratiometric spectral shifts that directly encode nanoparticle disassembly, enabling robust optical monitoring of intracellular nanometabolism with cell-type- and particle-size-resolution. Time-resolved imaging identifies protonation-induced lysosomal membrane destabilization as the primary driver of nanoparticle breakdown within 6-12 h. Supported by cryogenic correlative imaging and tissue-level tracking, this platform provides a promising optical framework for monitoring nanometabolism in living systems. It serves as a pivotal breakthrough in elucidating the mechanistic design rules required for the future development of carrier-free nanomedicines with predictable intracellular behavior.