Biodegradable poly(lactide-co-glycolide) coatings on magnesium alloys for orthopedic applications

Abstract

Polymeric film coatings were applied by dip coating on two magnesium alloy systems, AZ31 and Mg4Y, in an attempt to slow the degradation of these alloys under in vitro conditions. Poly(lactic-co-glycolic acid) polymer in solution was explored at various concentrations, yielding coatings of varying thicknesses on the alloy substrates. Electrochemical corrosion studies indicate that the coatings initially provide some corrosion protection. Degradation studies showed reduced degradation over 3 days, but beyond this time point however, do not maintain a reduction in corrosion rate. Scanning electron microscopy indicates inhomogeneous coating durability, with gas pocket formation in the polymer coating, resulting in eventual detachment from the alloy surface. In vitro studies of cell viability utilizing mouse osteoblast cells showed improved biocompatibility of polymer coated substrates over the bare AZ31 and Mg4Y substrates. Results demonstrate that while challenges remain for long term degradation control, the developed polymeric coatings nevertheless provide short term corrosion protection and improved biocompatibility of magnesium alloys for possible use in orthopedic applications.

Biodegradable magnesium alloys for orthopaedic applications: A review on corrosion, biocompatibility and surface modifications

“…Ostrowaski et al, reported on the corrosion and biocompatibility properties of the PLGA coating of varying thickness on AZ31and MgY4 alloy for orthopaedic applications [93]. In their study, two coatings of different thickness 1.6 μm and 41.8 μm were prepared on AZ31 alloy, whereas 1.6 μm and 62.1 μm thick coatings were deposited on MgY4 alloy.…”

Corrosion resistance of Zn–Al layered double hydroxide/poly(lactic acid) composite coating on magnesium alloy AZ31

“…3 [40,45]. Figure 4 presents the potentiodynamic polarization curves of the AZ31 substrate, the samples coated with the ZnAl-LDH coating and the LDH/PLA composite coating.…”

“…But some of them may release volatile organic compounds during the curing process and results in air pollution. Poly(lactic acid) (PLA) is a natural biocompatible and environment-friendly polymer material made from renewable resources such as corn starch, tapioca roots, chips or starch, or sugarcane [40]. It is worth mentioning that PLA is widely used as medical implants due to their characters of nontoxic, biodegradable and biocompatible [4,[41][42].…”

Hemocompatibility and selective cell fate of polydopamine-assisted heparinized PEO/PLLA composite coating on biodegradable AZ31 alloy

“…To enhance the corrosion resistance of the magnesium-based stents in physiological environments, biodegradable polymers such as poly(l-lactic acid) (PLLA), polycaprolactone (PCL), and poly(lactide-co-glycolide) (PLGA) have been widely applied to control the corrosion behavior and maintain surface biocompatibility for the magnesium-based stents [12,13]. However, although providing good protection and enhanced surface biocompatibility for the magnesium substrate, the polymer coatings did not maintain a reduction in corrosion rate over the long term and the inhomogeneous coating durability with gas pocket formation in the polymer coating will result in eventual detachment from the alloy surface [13].…”