Multifunctional DNA nanoplatform based on near-infrared AgInS2 QDs and rolling circle amplification for fluorescence imaging and therapy of breast cancer cells.

To enhance the therapeutic efficacy of breast cancer cells, a multifunctional nanoplatform was developed based on near-infrared AgInS2 quantum dots (AIS QDs) and rolling circle amplification (RCA). The AIS QDs were synthesized via an environmentally benign hydrothermal method using glutathione as a surface ligand, demonstrating favorable optical and photothermal properties. The RCA-generated long DNA strands served as a scaffold to co-assemble AS1411 aptamer-conjugated AIS QDs, gene therapeutic agent (DNAzyme), and doxorubicin (Dox), forming a multimodal nanoplatform (AIS QDs@RD). The polyvalent aptamer sequence carried by AIS QDs@RD enabled specific recognition of the overexpressed nucleolin on the membrane of MCF-7 cells (human breast cancer cells), allowing rapid discrimination between cancer and normal cells. AIS QDs@RD had excellent performance, including optimal excitation/emission wavelengths at 470/650 nm, a high photoluminescence quantum yield (PL QY) of 58.72%, a photothermal conversion efficiency (η) of 37.74%, and a Dox loading efficiency of 80.53%, which could significantly improve fluorescence imaging and drug delivery. Cytotoxicity assays revealed that treatment with AIS QDs@RD for 48 h, the viability of MCF-7 cells decreased to 31.8%, indicating potent antitumor activity, while minimal toxicity to normal cells. Therefore, this nanoplatform presents a promising strategy for targeted fluorescence imaging and therapy of breast cancer.