Polyvalent Aptamer-Functionalized NIR-II Quantum Dots for Targeted Theranostics in High PD-L1-Expressing Tumors.

AgS quantum dots (QDs) show superior optical properties in the NIR-II region and display significant clinical potential with favorable biocompatibility. However, inherent defects of low targeting and poor solubility necessitate practical modification methods to achieve the theranostics of AgS QDs. Herein, we used rolling circle amplification (RCA) techniques to obtain long single-stranded DNA containing the PD-L1 aptamer and C-rich DNA palindromic sequence. The C-rich DNA palindromic sequences can specifically chelate Ag and thus serve as a template to result in biomimetic mineralization and formation of pApt-AgS QDs. These QDs enable specific targeting and illuminate hot tumors with high PD-L1 expression effectively, serving as excellent molecular targeted probes. In addition, due to the high NIR-II absorption of AgS QDs, pApt-AgS QDs exhibit remarkable photothermal properties. And besides, polyvalent PD-L1 aptamers can recognize PD-L1 protein and effectively block the inhibitory signal of PD-L1 on T cells, enabling efficient theranostics through the synergistic effect of photothermal therapy and immune checkpoint blocking therapy. Summary, we enhance the biological stability and antibleaching ability of AgS QDs using long single-stranded DNA as a template, thereby establishing a theranostic platform that specifically targets PD-L1 high-expressing inflamed tumors and demonstrates excellent performance both and .