Fig. 1.

Preparation and characterizations of the NPs. (a) Schematic illustration of the preparation of the NPs. CuS NPs were reacted with ATPES to obtained CuS–NH₂ NPs, and then electrostatically bonded with negatively charged TGF-β1 pDNA. Then PC was coated on the NPs for biomimetic modification. TEM images of CuS (b, c) and CuS@PC (d, e) NPs, respectively. A thin layer (∼2 nm) of PC was observed on the NPs, indicating the successful surface modification of PC. (f) FTIR spectra of the NPs and PC. (g) Zeta potential of CuS, CuS–NH₂, and CuS/TGF-β1 NPs, respectively (n = 3). (h) Agarose gel electrophoresis assay of the unbinding pDNA in the supernatant after the reaction of CuS–NH₂ NPs and TGF-β1 pDNA. (i) marker; (ii) TGF-β1 pDNA; (iii-v) unbinding pDNA in the reaction of CuS–NH₂ and pDNA at the ratio of 10:1, 20:1, 30:1, respectively. Data are presented as means ± SD.