Figure 3: Enhancement factors as a function of loading concentrations of nanoparticles.

(a) Photoacoustic signal enhancement factor as a function of AuNR loading concentration below (blue points) and above LCST (red points). Insets show TEM images of the nanoconstructs with increased loading density of AuNRs. (b) Photoacoustic enhancement factor increases as CuS nanosphere loading concentration increases. Four loading concentrations are tested. Insets show TEM images of PNIPAM-CuS nanoconstructs with increased loading density of CuS. The concentration of both PNIPAM-AuNRs and PNIPAM-CuSs are matched to the OD=3.33 (for 1 cm optical path) by UV-Vis spectroscopy for equal comparison. The error bars represent the s.e. of mean of 300 frames of photoacoustic images. Scale bars are 250 nm.