Throughout this study polymer-templated nanoparticles were concentrated and rinsed where necessary using centrifugal filtration (Amicon® Ultra Centrifugal Filter, 10 kDa MWCO, Fisherbrand™ GT1R Centrifuge, 4000 RPM/min). Concentration was carried out by placing the nanoparticle solution in the upper part of the filter assembly, and using the centrifuge to selectively remove water until a desired volume is reached. Rinsing used the same approach but with successive steps of dilution with pure water or the desired aqueous solvent, followed by reconcentration to reduce the concentration of electrolyte or other small impurities.