Phagocytosis Modulated by a Pt^II Complex with Triphenylphosphine and 5-Heptyl-1,3,4-oxadiazole-2-(3H)-thione in a Microemulsion System

Abstract

In this work, the trans[Pt(L)₂(PPh₃)₂] complex (L: 5-heptyl-1,3,4-oxadiazole-2-(3H)-thione) was associated with a microemulsion (ME/Pt^II complex). The microemulsified system underwent physicochemical characterization, including pH, conductivity, rheology, zeta potential, and dynamic light scattering (DLS) measurements. The microemulsion system remained stable at a pH near 6.0, indicating biocompatibility, while the conductivity was between 7 and 8 μS cm^-1, with a hysteresis area of -0.06 Pa s^-1 for the ME/Pt^II complex. The DLS technique confirmed the presence of a microemulsion with particle sizes ranging from 10 to 200 nm. The polydispersity index for the ME/Pt^II complex system was close to 0.3, indicating a monodisperse system, with a zeta potential of -19.2 ± 4.49 mV. These results showed that the system containing the Pt^II complex and the microemulsion is thermodynamically stable. Subsequently, cell viability studies demonstrated that the ME/Pt^II complex system is not toxic to peripheral blood mononuclear cells (PBMCs). In the phagocytosis activity assay, the complex associated with the microemulsion showed an increase in the phagocytosis index, suggesting that the microemulsion (ME/Pt^II complex) has potential for new biological assays, such as antitumor and antibacterial.

Keywords:
Pt^II complexes; microemulsion; zeta potential; phagocytosis activity; cell viability; immunomodulatory