Modification of polylactic acid surface using RF plasma discharge with sputter deposition of a hydroxyapatite target for increased biocompatibility

Abstract

Surface modification of polylactic acid (PLLA) by plasma of radio-frequency magnetron discharge with hydroxyapatite target sputtering was investigated. Increased biocompatibility was demonstrated using studies with bone marrow multipotent mesenchymal stromal cells. Atomic force microscopy demonstrates that the plasma treatment modifies the surface morphology of PLLA to produce rougher surface. Infrared spectroscopy and X-ray diffraction revealed that changes in the surface morphology are caused by the processes of PLLA crystallization. Fluorescent X-ray spectroscopy showed that the plasma treatment also changes the chemical composition of PLLA, enriching it with ions of the sputtered target: calcium, phosphorus and oxygen. It is hypothesised that these surface modifications increase biocompatibility of PLLA without increasing toxicity.

Tuning the biomimetic behavior of scaffolds for regenerative medicine through surface modifications

“…Human hybrid endothelial cells saw enhanced attachment. A subsequent study by an associated group confirmed calcium phosphate deposition using X-ray fluorescence and demonstrated increased bone marrow stem cell viability on the treated scaffolds (Tverdokhlebov et al, 2015).…”

“…Human hybrid endothelial cells saw enhanced attachment. A subsequent study by an associated group confirmed calcium phosphate deposition using X‐ray fluorescence and demonstrated increased bone marrow stem cell viability on the treated scaffolds (Tverdokhlebov et al, ). However, sputter coating has severely limited penetration in 3D structures, so it is less viable than PECVD or other methods for surface modification of complex scaffolds.…”

Calcium Phosphate Layers Deposited on Thermal Sensitive Polymer Substrates in Radio Frequency Magnetron Plasma Discharge

“…The thermal patterning of the polymer during the deposition process is more pronounced at low pressures, as the SEM analysis showed. Previously, the authors of Reference [15] reported that the deposition of CaP thin films on polymeric materials (polylactic acids) in rf magnetron discharges conduce to different substrate patterning as a function of the treatment time.…”

“…Furthermore, the bombardment of the substrates with negatively charged oxygen (sputtered from the CaP target) causes the negative surface charging of the polymeric substrates, which affects the P resputtering rate and Ca/P ratio [9].At low rf powers, calcium phosphate ceramic coatings were obtained in magnetron sputtering discharges on polymeric substrates, such as: Polyethylene, polytetrafluoroethylene, polystyrene, polydimethylsiloxane or polylactic acid [9] with optimal adhesion characteristics [11] for biomedical applications. By using various pretreatment methods and interlayers, the adhesion of CaP coatings to the polymeric or metallic substrates were increased [11][12][13][14].The surface topography of polymeric substrates can be influenced by the exposure time to the plasma and electrical conditions applied during the plasma depositions or treatments [15]. It was shown [15] that the surface modification of polylactic acids produced by CaP depositions in rf magnetron discharges improved their biocompatibility, due to calcium and phosphorous embedding and the increase of surface roughness.…”

“…The surface topography of polymeric substrates can be influenced by the exposure time to the plasma and electrical conditions applied during the plasma depositions or treatments [15]. It was shown [15] that the surface modification of polylactic acids produced by CaP depositions in rf magnetron discharges improved their biocompatibility, due to calcium and phosphorous embedding and the increase of surface roughness.…”