Proteins are biological molecules, that are often less than 15nm in size. Here we show an investigation of a common blood protein, bovine serum albumin BSA. This protein is typically present as a mixture of its dimeric and monomeric form and will usually appear with an average size below 9nm. Heating this protein to its melting point and then rapidly cooling the sample down to 4 degrees C leads to the formation of an interesting homogeneous and monodisperse nanoparticle of near 30nm size.

We show data of the native protein, its nanoparticulate form and the mixture of the two. Dynamic light scattering (DLS) was used for the size characterization, static light scattering (SLS) for the determination of the molecular weight.

Light scattering is a versatile measurement technique and perfectly suited to investigate protein molecules as well as the assembly of biomolecules in solution.