I am working on protein conjugation into nanoparticles. Magnetic nanoparticles were washed with DI water and TBS buffer and then combined with eGFP fused protein for 24 hrs. After removing the supernatant, the nanoparticles were washed with TBS for 6 times, but there is still a lot of non-specific binding of eGFP on nanoparticles, as demonstrated by fluorescence microscopy.

If I want to reduce protein non-specific binding to magnetic nanoparticles, does anyone has any good suggestions on how to wash the conjugated nanoparticles? Or some other simple methods? Thank you very much.