Nanostructured hydroxyapatite/poly(lactic-co-glycolic acid) composite coating for controlling magnesium degradation in simulated body fluid

Abstract

Biodegradable magnesium (Mg) and its alloys have many attractive properties (e.g. comparable mechanical properties to cortical bone) for orthopedic implant applications, but they degrade too rapidly in the human body to meet clinical requirements. Nanostructured hydroxyapatite (nHA)/poly(lactic-co-glycolic acid) (PLGA) composite coatings provide synergistic properties for controlling degradation of Mg-based substrates and improving bone-implant integration. In this study, nHA/PLGA composites were spin coated onto Mg-based substrates and the results showed that the nHA/PLGA coatings retained nano-scale features with nHA dispersed in PLGA matrix. In comparison with non-coated Mg, the nHA/PLGA composite coated Mg increased the corrosion potential and decreased the corrosion current in revised simulated body fluid (rSBF). After 24 h of immersion in rSBF, increased calcium phosphate (CaP) deposition and formation of Mg-substituted CaP rosettes were observed on the surface of the nHA/PLGA coated Mg, indicating greater bioactivity. In contrast, no significant CaP was deposited on the PLGA coated Mg. Since both PLGA coating and nHA/PLGA coating showed some degree of delamination from Mg-based substrates during extended immersion in rSBF, the coating processing and properties should be further optimized in order to take full advantage of biodegradable Mg and nHA/PLGA nanocomposites for orthopedic applications.

Biodegradable Metallic Wires in Dental and Orthopedic Applications: A Review

“…Although plenty of coating methods such as electrodeposition [152], sol-gel and dipping [153], chemical conversion [154], anodization [155], vapor deposition [156], spin [157], and alkali treatment [158] have been proposed to inhibit rapid corrosion of Mg and its alloys, just few of them are effective and flexible enough for the formation of a uniform coating with desired thickness on the non-flat surfaces such as wires. Simultaneously, the adhesion between the substrate and the coating film is another concern that should be considered.…”

Optimization of Cell Adhesion on Mg Based Implant Materials by Pre-Incubation under Cell Culture Conditions

“…In addition, the micro- [22,23] or nanostructure of the HA crystallites deposited on the surface can improve cell adhesion and reduce the corrosion rate [24]. To improve the performance of the CaP coatings also composites with degradable polymers were prepared [25,26]. …”

Testing the in vitro performance of hydroxyapatite coated magnesium (AZ91D) and titanium concerning cell adhesion and osteogenic differentiation

“…Another strategy was pursued by Johnson et al that used electrospinning of nanostructured HA in combination with poly(lactic-co-glycolic acid) as surface treatment of AZ91 [37]. They postulated a slower degradation rate and a higher bioactivity resulting of the modification when examining in simulated body fluid.…”