The effect of capping agent on morphology, surface functionalization, and bio-compatibility properties of KTiOPO nanoparticles.

KTiOPO (KTP) nanoparticles (NPs) are potential materials as biolabels for long-term imaging. Optimizing their properties can lead to higher imaging efficiency and lower cytotoxicity and side effects. In this study, these nanoparticles were synthesized using the co-precipitation method and capping agents of oxalic acid and glycine. The capping agent's effect on the structural, optical, morphological, hemocompatibility, and biocompatibility properties of the obtained nanoparticles was studied. The smallest (12.56 nm) grain size and the lowest lattice strain (0.0024) were obtained using 1:1 and 1:3 mol ratios of glycine, respectively. Oxalic acid as a capping agent resulted in needle-type, flower-type, and oval-form NPs. Polygonal tablet form, cubic, and polyhedral forms of KTP NPs were synthesized using glycine. C-O-H bending bonds, O-H, N-H, and carbonyl (C=O) stretching bonds remain on the surface of synthesized NPs after heat treatment and functionalization of their surface. Our results showed that the surface functionalization modifies the biocompatibility properties of NPs. The 1:3 mol ratio of oxalic acid as a capping agent resulted in the perfect KTP NPs for long-term imaging studies. The presence of hydroxyl groups improved the biocompatibility of obtained KTP NPs using a 1:3 mol ratio of oxalic acid over time. The needle form of obtained NPs resulted in an increase in cell cytotoxicity at higher concentrations.