I am working on the interaction of silver nanoparticle in different size with acetylcholinestrase. i saw the blue shift in UV-Vis peak for treated nanoparticle with protein than blank one.
The surface plasmon of NPs is, as it name indicates, a process that happens in the surface. If you change it, you are affecting the plasmon and the UV-Vis spectrum too. Anyway, how much is the peak shifted?
Nanoparticle size and coating materials are also important factors to cause the SPR shift. What could that be? The 10 nm shift can be occurred by medium change or ionic interaction when enzyme or proteins added, which is not a substantial shift so better be careful.
PVA and proteins usually have no interaction, which won't occur SPR shift. Why don't you adjust both sample buffer as same as possible and recheck the shift. I assume that it is due to disimilar dielectric constant of the medium (buffer vs PVA)
i have to notice that in some cases( i mean 69nm nanoparticle with same coating) we did not see any change in UV-Vis peak. while, the nanoparticle concentration, buffer, protein concentration, time and temperature were same as 42nm and 24nm nanopartocle.