A) Schematic of communicating nanoparticles. B) Experimental timeline for testing communicating nanoparticles. C) Thermographic imaging of photothermal PEG-nanorod heating. At 72 hrs post NR- or saline-injection (10 mg Au/kg), mice were co-injected with coagulation-targeted (FXIII- NWs) and untargeted (FXIIIControl-NWs) and their right flanks were broadly irradiated (810 nm, ~0.75 W/cm2, 20 min) under infrared thermographic surveillance to reveal surface temperatures. D) Overlaid fluorescence reflectance image of targeted and untargeted Receiving NP homing. At 24 hrs post-irradiation, whole-animal fluorescence imaging revealed the distributions of coagulation targeted (FXIII-NWs, green) and untargeted (FXIIIControl-NWs, red) Receiving NPs. E) Quantification of Receiving NP homing in irradiated vs contralateral unirradiated tumours. After whole-animal imaging, mice were dissected and the fluorescence of each tumour was measured to quantify the homing of Receiving NPs. (* indicates p=0.02, paired, two-sided t-test; n=4; error bars=std. dev.) F) Schematic of a nanosystem that communicates autonomously in the presence of tumour receptors. G) Experimental timeline for testing the autonomous nanosystem in vivo. H) Intraoperative imaging of NW Receivers. Nu/nu mice bearing a single MDA-MB-435 tumour were intravenously injected with communicating (tTF-RGD + FXIII-NWs) or control (tTF-RGD + FXIIIControl-NWs) systems, FXIII-NWs alone, or NWs targeted by the peptide used to direct Signalling component tumour homing (1 mg/kg tTF-RGD). At 24 hrs post-injection, tumours were surgically exposed for fluorescent intraoperative imaging of NW homing. (FXIIICont-NWs = FXIIIControl-NWs) I) Tumour specificity of the autonomous nanosystem. Excised organs from mice injected with autonomously communicating nanosystems (tTF-RGD + FXIII-NWs) were imaged for NW fluorescence at 24 hrs post-injection (1 mg/kg tTF-RGD). J) Histopathological analysis of NW Receivers. Histopathological sections from experiments in H). At 24 hrs post-NW injection, mice were sacrificed and tumours were analyzed for NW Receiver distribution in histology. (Red= CD31 blood vessel stain, Blue= DAPI nuclear stain, Green=NW Receiver distribution, RGD-NW scale bar=100 μm; All others = 200 μm)