Characterisation of AgPEG. (A) UV-Vis absorbance spectrum showing a significantly shifted absorption peak at 894 nm. The original silver nanoparticle spectrum is shown for comparison. (B) TEM image showing homogeneous nanoparticles 100 days post-synthesis (scale bar 100 nm), with inset particle diameter distribution. (C) AFM topography image in air showing disperse homogeneous nanoparticles 100 days post-synthesis (scale bar 1 μm), with upper inset particle height distribution. Lower inset shows AgPEG nanoparticles dried in ethanol (scale bar 1 μm), revealing absorption of small nanoparticles in PEG.