Fig. 4. The cholesterol-deficient cell membrane inhibited the clearance of CISP by monocytes in the blood.

a, b Fluorescence images of tumors in mice treated with CISP (a) and the mean fluorescence intensity of DiD in tumors (b) (n = 3 mice). Membrane of CISP were sourced from CTLL2-PD1 that were treated with different concentration of β-CD. c, d mean fluorescence intensity of DiD in blood (c) and fluorescence images of blood at 4 h post injection (d) (n = 3 mice). e Schematic illustration showing the process to detect nanoparticles in blood. f, g Fluorescence images of plasma at 0.5 h post injection (f) and the mean fluorescence intensity of DiD in plasma (g) (n = 3 mice). h Fluorescence images of serum in mice (n = 3 mice). i Concentration of DiD in serum detected by fluorescence spectrophotometer (n = 3 mice). j, k Uptake of nCISP and CISP by lymphocytes in the blood detected by flow cytometry at 0.5 h post injection (j) and the relative mean fluorescence intensity of DiD in lymphocytes (k) (n = 5 mice). l, m Uptake of nCISP and CISP by neutrophils in the blood detected by flow cytometry (l) and the relative mean fluorescence intensity of DiD in neutrophils (m) (n = 5 mice). n, o Uptake of nCISP and CISP by monocytes in the blood detected by flow cytometry (n) and the relative mean fluorescence intensity of DiD in monocytes (o) (n = 5 mice). Data represent mean ± SEM (b, c, g, i, k, m, o). Statistical significance was determined by one-way ANOVA test in b, c, and it was two-sided and adjustments were made for multiple comparisons. Student’s two-sided t test was used for the statistical analysis in g, k, m, o. The experiments for c, d, f, g, n, o were repeated three times independently with similar results. Source data are provided as a Source Data file. MFI mean fluorescence intensity, QFN Quercetin-ferrum nanoparticles, QFN₇₁₇ QFN loaded with SR-717, nCISP normal-Cholesterol cell membrane-coated ICB agent and QFN₇₁₇, CISP low-cholesterol membrane-coated ICB agent and QFN₇₁₇.