Characterization of cellular uptake, endosome escape, and transfection efficiency of TPH NCs. (A) Cellular uptake of RA FLS treated YOYO-1 labeled PEI25 K/pDNA, TKPF/pDNA and TPH NCs by Flow cytometry analysis. (B) Quantitative cellular uptake efficiency and (C) mean fluorescence intensity of PEI25 K/pDNA, TKPF/pDNA, and TPH detected by flow cytometry. (D) Fluorescence microscopy images of RA FLS after incubation with PEI25 K/pDNA, TKPF/pDNA, and TPH. Scale bar: 200 μm. (E) CLSM images of RA FLS incubated with TPH NCs. Scale bar: 50 μm. (F) Fluorescence images of RA FLS treated by PEI25 K/pDNA, TKPF/pDNA and TPH NCs using pEGFP after transfection for 24 h. Scale bar: 200 μm. (G) Quantitative transfection efficiency result analyzed through flow cytometry. (H) Mean fluorescence intensity by flow cytometry. Data are shown as mean ± SD (n = 3). *p < 0.05, **p < 0.01, ***p < 0.001.