Fig. 5. Capturing histones by HNPs in the bloodstream.

a Behavior of Rho–histones and FITC–PEGHNPs in the murine bloodstream was observed by laser-scanning confocal microscopy. The FITC (Ex = 488 nm, Em = 520 nm) and FRET (Ex = 488 nm, Em = 570 nm) channels were recorded for 10 min before and after the histone injection. The fluorescence intensity of FRET or FITC in the bloodstream. The zero-time point corresponds to the time of the histone injection. Data represent the means ± s.d. n = 4 Rho; rhodamine, FITC fluorescein isothiocyanate. b Biodistribution of naked HNPs and PEGHNP12 in histone pre-treated mice. Mice were intravenously injected with radio-labeled naked HNPs or PEGHNP12 at 20 s after the histone treatment (IV). Twenty-four-hour after the injection, the distribution of HNPs in the plasma and each organ was measured. Data represent the means ± s.d. n = 5. c, d Biodistribution of Cy5-histones. Mice were intravenously injected with Cy5-histone after PEGHNP12 injection. Then, the biodistribution of cy5-histones were monitored by in vivo imaging system. d Ex vivo image at 1 h after the histone injection. H heart, Lu lungs, Li liver, Sp spleen, K kidneys, In intestine.