Despite the multitude of therapeutic agents available
to treat
prostate cancer (PC), there are still no effective and safe measures
to treat the tumor. It remains a challenge to develop a simple approach
to target PC with specific antibodies. In our study, D2B monoclonal
antibodies against a prostate-specific membrane antigen (PSMA) were
used. We investigated the functionalization of gold nanoparticles
(AuNPs) with D2B to generate favorable physicochemical and biological
properties that mediate specific binding to PC. For this purpose,
AuNPs with a size of about 25 nm were synthesized in water using sodium
citrate as a reducing and stabilizing agent and then coated with D2B.
Major physicochemical properties of naked and D2B-coated AuNPs were
investigated by ultraviolet–visible (UV–vis) spectroscopy,
dynamic light scattering (DLS), and zeta potential measurements. The
successful binding of D2B to AuNPs-citrate caused a 15 nm red shift
in the UV–vis. This was assessed by DLS as an increase in zeta
potential from ∼−45 to ∼−23 mV and in
the size of AuNPs from ∼25 to ∼63 nm. Scanning electron
microscopy confirmed the size shift of AuNPs, which was detected as
an exterior organic layer of D2Bs surrounding each AuNP. Even at high
exposure levels of the bioconjugates, PSMA-PC-3 cells exhibited minimal
cytotoxicity. The specific and dose-dependent binding of AuNPs-D2B
to PC-3-PSMA cells was validated by flow cytometry analysis. Our data
provide effective drug delivery systems in PC theranostics.