Analysis of the urine of the mice one hour after injection indicates that theranostic LbL NPs yield significantly elevated levels of the peptide reporter fragment in the urine in a (a) pancreatic cancer flank model, (b) a metastatic model of colorectal cancer, and (c) two models of ovarian cancer. (d) Theranostic LbL NPs were intravenously administered via tail vein injection to the subcutaneous flank ovarian cancer model to provide an siRNA dosage of 0.5 mg/kg to silence the model gene luciferase in vivo. (e) Bioluminescence levels were monitored over three days using an IVIS imaging device, also used to generate the images shown in a–c. Error bars represent SEM, and statistical analysis of panels a and b uses students t-tests, while panel c uses a one-way ANOVA with a Dunnett post-hoc test and alpha of 0.05. Panel e uses a one-way ANOVA with a Tukey post-hoc test and alpha of 0.05.