Abstract
Considerable efforts have been made to synthesize and characterize protein-nanoparticle conjugates (protein-NPs) for their promising applications in bionanotechnology. However, protein concentration determination in the protein-NPs has so far not been reported. In this Letter, we present a simple and nondestructive approach to quantify the protein concentration in the protein-NPs aqueous solution using circular dichroism (CD) spectroscopy. Carbon dots (∼4 nm), gold nanoparticles (∼10 nm), and polyethylene glycol (PEG, molecular weight ∼3000) were either physically mixed or covalently conjugated (not in the case of gold nanoparticles) with proteins (human transferrin, human serum albumin, and ovalbumin). We were able to quantify the protein concentration in the protein-nanoparticle conjugates using a calibration curve from the CD spectra.
