Effect of Palmitoyl Nanogold Particles on the Subzero Thermal Properties of Phosphate Buffered Saline Solutions

Extensive studies document the effect of nanoparticles on thermal properties of fluids, such as thermal conductivity, although very few exist at subzero temperatures. The current study reports the effect of 1.4 nm palmitoyl nanogold particles (NPs) on the freezing properties of phosphate buffered saline solutions with the help of a differential scanning calorimeter. The results show that NPs have a complex effect on the two properties of interest, i.e., homogeneous nucleation temperature $(Th)$ and phase change temperature (or the melting temperature, $Tm$⁠). The homogeneous nucleation temperature was significantly elevated at a concentration of 1 nM/ml NPs with 0.167% (v/v) DMSO, and 3 nM/ml NPs with 0.50% (v/v) DMSO concentration, whereas at the other concentrations (1.2 nM/ml NPs with 0.20% DMSO, 1.5 nM/ml NPs with 0.25% DSMO, and 6 nM/ml NPs with 1% DMSO), it was significantly depressed. A similar phenomenon was also noticed in the measured values of the melting temperature of PBS solutions.