Protein-nanoparticle conjugate purification methods

A method of purifying a protein-nanoparticle conjugate, the method comprising:

• contacting a mixture of the protein-nanoparticle conjugate, free protein, and a buffer to a multimodal medium to separate the protein-nanoparticle conjugate from free protein, wherein the multimodal medium has a size exclusion mode and a capture mode and the multimodal medium comprises a polysaccharide and has a core functionalized with ligands that are both hydrophobic and positively charged, wherein the protein-nanoparticle conjugate is excluded from entering pores of the medium and the free protein is captured in the multimodal medium;
• and
• collecting the protein-nanoparticle conjugate from the medium in flow-through, thereby purifying the protein-nanoparticle conjugate from the free protein.