Nanoparticle size and production efficiency are affected by the presence of fatty acids during albumin nanoparticle fabrication

Abstract

We have previously identified extensive glycation, bound fatty acids and increased quantities of protein aggregates in commercially available recombinant HSA (rHSA) expressed in Oryza sativa (Asian rice) (OsrHSA) when compared to rHSA from other expression systems. We propose these differences may alter some attributes of nanoparticles fabricated with OsrHSA, as studies have associated greater quantities of aggregates with increased nanoparticle diameters. To determine if this is the case, nanoparticles were fabricated with OsrHSA from various suppliers using ethanol desolvation and subsequent glutaraldehyde cross-linking. All nanoparticles fabricated with OsrHSA showed larger diameters of approximately 20 to 90nm than particles fabricated with either defatted bovine serum albumin (DF-BSA) (100.9 ± 2.8nm) or human plasma albumin (pHSA) (112.0 ± 4.0nm). It was hypothesized that the larger nanoparticle diameters were due to the presence of bound fatty acids and this was confirmed through defatting OsrHSA prior to particle fabrication which yielded particles with diameters similar to those fabricated with pHSA. For additional conformation, DF-BSA was incubated with dodecanoic acid prior to desolvation yielding particles with significantly larger diameters. Further studies showed the increased nanoparticle diameters were due to the bound fatty acids modulating electrostatic interactions between albumin nanoparticles during the desolvation and not changes in protein structure, stability or generation of additional albumin oligomers. Finally the presence of dodecanoic acid was shown to improve doxorubicin loading efficiency onto preformed albumin nanoparticles.