Influence of HSA on the properties of OA/OAM monolayers and the growth of calcium oxalate

The properties of octadecanoic acid/octadecylamine (OA/OAM) monolayers and crystal growth of calcium oxalate induced by the monolayers on subphases containing supersaturated calcium oxalate (CaC2O4) solution and different concentrations of human serum albumin (HSA) (0.00, 0.02, 0.08, and 0.10 wt.%) were studied in this paper. The results demonstrated that HSA could be adsorbed by OA/OAM monolayers, which was confirmed by Fourier transform infrared (FTIR) spectra, UV-Vis absorption spectra, respectively. The adsorption of different concentrations of HSA changed the properties of the monolayers, which resulted in the appearance of different crystal morphologies of CaC2O4 such as calcium oxalate monohydrate (COM), calcium oxalate dihydrate (COD), calcium oxalate trihydrate (COT). HSA could promote the growth of COT crystals. COM only formed on the CaC2O4 supersaturated solution containing 0.08% HSA. The formation process of COM was tracked in kinetic experiments by Scanning electron microscopy (SEM), transformation from COT into COM could be seen, which would take about 480 h. In order to prohibit the transformation, 1,2-bis(O-aminophenoxy)ethane-N,N,N,N-tetracetic acid (BAPTA) was synthesized and added to the above subphase, expected results were obtained.