Tannic acid cross-linked polyethylenimine quantum dot nanoclusters for efficient DNA release.

In this work, we present a strategy for synthesizing nanoclusters (TC25NCs) by bonding formaldehyde functionalized tannic acid (TA-CHO) with polyethyleneimine quantum dots (CQDs). The synthesized vector effectively loads DNA and exhibits significant pH-responsive release, thereby facilitating traceable DNA delivery in cells. The TC25NCs/DNA demonstrated negligible cytotoxicity at high N/P ratios, with cell viability exceeding 80 %. Utilizing the excellent fluorescence imaging capability of TC25NCs, real-time monitoring of cell uptake and quantitative analysis of uptake efficiency were achieved. The results indicated that TC25NCs exhibited significant fluorescence effects at an excitation wavelength of 350 nm, with transfection efficiencies of 58.88 %, 42.69 %, and 35.25 % in 293T, HepG2, and HeLa cells, respectively, which were substantially higher than those of other single vector materials. This work not only provides an effective carrier for DNA delivery, but also offers valuable insights into tailoring surface chemistry and designing vectors for precise control over delivery process to achieve the visual delivery of genes.