A thermo-responsive rewritable plasmonic bio-memory chip has been successfully fabricated on an indium tin oxide (ITO) glass slide by assembling core-satellite gold nanoclusters with different size of gold nanoparticles (AuNPs) using double-strand DNA (dsDNA) linker. And the prepared 70@DNA20@13 gold nanoclusters (AuNCs) exhibited more stable and greater photothermal conversion ability. With short time irradiation by 633 nm microbeam laser, every individual AuNCs could be excited and remove the satellite AuNPs on its surface. Especially, in the dissociation process of AuNCs with 3−5 satellite, its color would change from yellow to green, which showed more significant reduction in the red channel of the dark-field microscopy (DFM) images and could be defined to state “0” and “1” respectively. Besides, this plasmonic nano bio-memory could transform cyclically its state between 0 and 1 which exhibited excellent rewritable ability.

Semiconducting polymer nanoparticles (SPNs) have shown great promise in second near-infrared window (NIR-II) phototheranostics. However, the issue of long metabolic time significantly restricts the clinical application of SPNs. In this study, we rationally designed a biodegradable SPN (BSPN50) for NIR-II fluorescence imaging-guided photodynamic therapy (PDT). BSPN50 is prepared by encapsulating a biodegradable SP (BSP50) with an amphiphilic copolymer F-127. BSP50 is composed of NIR-II fluorescent diketopyrrolopyrrole (DPP) segment and degradable poly(phenylenevinylene) (PPV) segment with the ratio of 50/50. BSPN50 has both satisfactory degradability under myeloperoxidase (MPO)/hydrogen peroxide (H₂O₂) and NIR-II fluorescence emission upon 808 nm laser excitation. Furthermore, BSPN50 shows good photodynamic efficacy under 808 nm laser irradiation. BSPN50 shows a faster degradation rate than BSPN100 which has no PPV segment both in vitro and in vivo. In addition, BSPN50 can effectively diagnose tumor via NIR-II fluorescence imaging and inhibit the tumor growth by PDT. Thus, our study provides a rational approach to construct biodegradable nanoplatforms for efficient tumor NIR-II phototheranostics.