AtomicForce Microscopy Probing of Receptor–NanoparticleInteractions for Riboflavin Receptor Targeted Gold–DendrimerNanocomposites.

Riboflavin receptors are overexpressedin malignant cells fromcertain human breast and prostate cancers, and they constitute a groupof potential surface markers important for cancer targeted deliveryof therapeutic agents and imaging molecules. Here we report on thefabrication and atomic force microscopy (AFM) characterization ofa core–shell nanocomposite consisting of a gold nanoparticle(AuNP) coated with riboflavin receptor-targeting poly(amido amine)dendrimer. We designed this nanocomposite for potential applicationssuch as a cancer targeted imaging material based on its surface plasmonresonance properties conferred by AuNP. We employed AFM as a techniquefor probing the binding interaction between the nanocomposite andriboflavin binding protein (RfBP) in solution. AFM enabled precisemeasurement of the AuNP height distribution before (13.5 nm) and afterchemisorption of riboflavin-conjugated dendrimer (AuNP–dendrimer;20.5 nm). Binding of RfBP to the AuNP–dendrimer caused a heightincrease to 26.7 nm, which decreased to 22.8 nm when coincubated withriboflavin as a competitive ligand, supporting interaction of AuNP–dendrimerand its target protein. In summary, physical determination of sizedistribution by AFM imaging can serve as a quantitative approach tomonitor and characterize the nanoscale interaction between a dendrimer-coveredAuNP and target protein molecules in vitro. [ABSTRACT FROM AUTHOR]