gms | German Medical Science

Infection and inflammation are among the most-feared complications following implantation of xenomaterials. One effective strategy against such incidents emerges from blending or impregnating implants or nanocarriers with suitable prophylactic drugs [1]. However, implanted materials tend to form biological coatings, which often interfere with drug release and integration into tissue [2]. Since nanoparticles (NPs) are characterised by particular high surface/volume ratios, their interaction with matrix components may markedly differ from planar surfaces. Polylactide (PLA) is a well-established biodegradable material of which oligomer chain length distribution is varied in order to control degradation time [3], [4]. However, impact of dispersity of initial protein layers on coatings has been rarely investigated yet. Therefore, this study addresses this question using a model setting comprising of homopolymeric PLA polymers differing in mean molecular weight (Resomer R202H <R203H <R207H <L207H) and two physiologically relevant proteins ubiquitous in human serum, albumin (HSA) and fibrinogen (HFG). Protein binding to planar material was assessed by surface plasmon resonance (SPR) [5] and corona formation around NPs by nanoparticle tracking analysis (NTA) [6]. On planar surfaces, the adsorbed amount of protein is increased for all resomers regarding each particular protein HSA and HFG, while no substantial differences were found between enantiomeric variants (R, L). The number of adsorbed molecules was similar for both proteins ranging 18–26 fmol/mm². Film formation was completed <3 min. The affinity towards PLA was calculated HFG <HSA. With PLA NPs, sizes of hydrodynamic diameter for R202H and R203H were comparable, ranging 270–290 and 280–300 nm, respectively. Addition of either protein broadened the size distribution markedly (range 100–500 nm), indicating conglomeration with protein subspecies of HSA or HFG, of which were identified 6 and 3, respectively, in the range 20–400 nm. Kinetics of corona formation were completed <5 min and could not be resolved further due to technical limitations. These data suggest that the choice of homopolymeric PLA polymers in implantation can be based on material properties such as, among others, degradation rate and mechanical stability. Chemical surface modification is expected to allow for control of the protein species involved in formation of the initial layer by the interaction between implant and tissue.