Targeting prostate cancer cells with D2B-gold Nanoparticles

In this study, gold nanoparticles (AuNPs) with an estimate diameter of 25 nm have been synthesized in water using sodium citrate as both reducing and stabilizing agent at ~95 C and in the presence of sodium hydroxide. The generated AuNPs were characterized using ultraviolet-visible spectroscopy (UV-Vis), dynamic light scattering (DLS) and Zeta potential measurements. Additionally, AuNPs were coated with D2B, a monoclonal antibody (mAb) recognizing an extracellular epitope of the human prostate specific membrane antigen (hPSMA). Binding of antibodies to PSMA induces its endocytosis, thereby marking PSMA as a docking site for the delivery of therapeutic agents. To attain a stabilized and covalent bond between D2B and AuNPs the strong S-Au bond was exploited; so, the sulfhydryl group (SH) in a cysteine of the D2B was utilized. Binding of D2B to AuNPs-citrate colloidal solution caused a red shift with a higher wavelength of about 15 nm in the UV-Vis spectra. Furthermore, as a confirmation of the successful conjugation, DLS revealed an increase in both the AuNPs size from ~25 to ~63 nm and Zeta potential measurements for AuNPs-citrate from ~ -45 mV to -23 mV. The cytotoxicity of D2B-AuNPs was assessed using the WST-1 cell proliferation assay and the agarose gel DNA fragmentation method. Finally, the specific delivery and binding of our customized NPs was tested using flow cytometry and western blot. Our results pave the way for further research using coated NPs as vehicles for drug delivery in in vitro as well as in vivo models.