a Schematic of PEGHNPs synthesized by free-radical copolymerization of functional monomers. b TEM image of PEGHNPs. The experiment was repeated two times, five pictures were taken in each experiment. c QCM analysis of the histone–PEGHNP interaction. The surface of the QCM cell was functionalized with histones and solutions of PEGHNPs were added to the QCM cells. Data represent the means of independent duplicate measurements. d Histone capture rate of PEGHNPs. Histone (600 µg/ml) and PEGHNPs (3000 µg/ml) were ultracentrifuged after the incubation for 30 min. Then, free histones were measured. Data represent the means ± s.d. n = 3. e Distribution of PEGHNPs in the plasma 3 h after the intravenous injection of [14C]-labeled PEGHNPs. Data represent the means ± s.d. n = 5. Blue bars; M.W of PEG: 500, yellow bar; M.W of PEG; 1500, and red bar; M.W of PEG; 4000.