Inhibitory effect of NPs on B16F10 cell migration and invasion in vitro and anti‐implantation effect in vivo. A) Images and D) quantitative analysis of invaded B16F10 cells after separate incubation with PBS, LMWH, LT NPs, PLT NPs, LT/DOX NPs, and PLT/DOX NPs for 48 h. The invaded cells were stained with crystal violet (means ± SD, n = 3). *** indicates p < 0.001. B) Images and C) healing rate from the wound healing assay after separate incubation with free DOX, LMWH, LT NPs, PLT NPs, LT/DOX NPs, and PLT/DOX NPs for 24 h (means ± SD, n = 3). * indicates p < 0.05. E) Detection of MMP‐9 in B16F10 cell culture medium by ELISA after separate incubation with PBS, LMWH, LT NPs, PLT NPs, LT/DOX NPs, and PLT/DOX NPs for 30 h (means ± SD, n = 3). *** indicates p < 0.001. F) The fluorescence intensity of platelets adhering to B16F10 cells in vitro. + indicates coincubation with calcein‐AM labeled platelets, – indicates no coincubation with calcein‐AM labeled platelets (means ± SD, n = 3). *** indicates p < 0.001. G) Expression of MMP‐9 in B16F10 cells tested by Western blot after separate incubation with (a) PBS, (b) LMWH, (c) LT NPs, (d) PLT NPs, (e) LT/DOX NPs, and (f) PLT/DOX NPs for 30 h. H) Detection of E‐cadherin and N‐cadherin in B16F10 cell culture medium by Western blot after separate incubation with (a) PBS−, (b) PBS+, (c) LMWH+, (d) LT NPs+, (e) PLT NPs+, and (f) PLT/DOX NPs+ for 30 h, + means coincubation with platelets after administration. J) CLSM images of the frozen sections of lungs. The implanted B16F10 tumor cells were identified by CFSE staining (yellow). Cell nuclei were stained with DAPI (blue). The scale bar indicates 200 µm.