Neutral and charged copper(I) complexes on hydrophilic gold nanoparticles and nanorods: loading and structural studies for biomedical applications

Gold nanoparticles and nanorods (AuNPs, AuNRs) are successfully applied in drug and gene delivery, photothermaltherapy, biosensors, and biotechnologies.[1-3] Their wide success is due to unique chemical and physical properties, biocompatibility, and well-established strategies for surface modification.[3] In this framework AuNPs and AuNRs were synthetized with the aim to obtain strongly hydrophilic materials, suitable for drug delivery.[4-6] AuNPs were used as drug delivery systems for two different copper(I)-based anti-tumor complexes namely [Cu(PTA)4]+[BF4]- (A; PTA = 1,3,5-triaza-7-phosphadamantane) and [HB(pz)3Cu(PCN)] (B; HB(pz)3 = tris(pyrazolyl)borate, PCN = tris(cyanoethyl)phosphane).[7] In the homoleptic, water-soluble compound A, the metal is tetrahedrally arranged in a cationic moiety. Compound B is instead a mixed-ligand (scorpionate/phosphane), neutral complex insoluble in water. The loading procedures and efficiency of A and B complexes on the AuNPs were investigated, with the aim to optimize the bioavailability. The non-covalent interactions of A and B with the AuNPs surface were deeply studied by means of DLS, UV-Vis, FT-IR and HRXPS measurements. AuNPs-A system proved to be more stable and efficient than AuNPs-B system. In fact, the drug loading reached 90% for AuNPs-A.