Sustained release of strontium (Sr²⁺) from polycaprolactone/poly (D,L-lactide-co-glycolide)-polyvinyl alcohol coaxial nanofibers enhances osteoblastic differentiation

Abstract

Electrospun nanofibers mimic the bone’s extra-cellular matrix and represent an alternative implant coating to enhance implant osseointegration. Approximately 99% of the strontium (Sr2+) in our body deposits in the bone and serves as a stimulator of bone formation. The purpose of this study was to develop an Sr2+-doped coaxial polycaprolactone (PCL)/poly(D,L-lactide-co-glycolide) (PLGA)-polyvinyl alcohol (PVA) nanofiber coating to enhance the osseointegration. An optimized PCL/PLGA (1:1 v/v) sheath fiber formula was identified to match the nanofibers degradation to the implant osseointegration physiology. Scanning electron microscopy images showed that the Sr2+-doped nanofibers had a less dense structure and larger porosity than the nanofibers without Sr2+ doping. A sustained Sr2+ release from the PCL/PLGA-PVA coaxial nanofibers was observed for over two months. The indirect and direct cellular contact studies confirmed the biocompatibility of the Sr2+-doped PCL/PLGA-PVA coaxial nanofibers. The Sr2+-doped nanofibers provided further and significant enhancement of the differentiation of murine pre-osteoblast MC3T3-E1 cells. These findings indicate that Sr2+-doped PCL/PLGA-PVA coaxial nanofibers have a great potential to be applied as a new implant coating matrices.

Osteoblastic differentiation and bactericidal activity are enhanced by erythromycin released from PCL/PLGA-PVA coaxial nanofibers

“…24 Since the degradation of PCL is slow (∼6 months), 25 we modified and optimized a formula of coaxial PCL/(PLGA)-PVA NF coating using the faster degradation nature of PLGA (∼1 month). 19 We found that a strontium (Sr)-doped coaxial PCL/PLGA)-PVA NF coating had a close match between NF coating degradation and implant osseointegration physiology. A sustained Sr release from the PCL/PLGA-PVA NF coating was observed for over 2 months.…”

“…20,21 In the past two decades PCL and PLGA has been used as devices for the delivery of drugs 20,22 and other compounds. 19,23 For example, we 18 developed electrospun coaxial doxycycline (Doxy) doped PCL/PVA NF coating. We noticed that a slow degradation of the PCL sheath fiber concurrently reduced the Doxy diffusion from the PVA core fibers.…”

Electrospun Nanofibers Containing Strontium for Bone Tissue Engineering

“…Local delivery of Sr 2+ from bone substitutes such as nanofibers is considered a promising approach to treat bone defects [78]. In the research of Chen et al, a coaxial PCL/PLGA-PVA nanofiber coating doped with Sr 2+ was developed to enhance osseointegration [89]. It was observed from PCL/PLGA-PVA nanofibers that Sr 2+ was continuously released for more than two months.…”

“…Many studies have shown that adding bioactive substances such as hydroxyapatite (HAp) to PCL can increase the hydrophilicity of PCL. The study found that due to the difference in ionic radius, the solubility of Sr-substituted hydroxyapatite (SrHAp) is higher than that of pure HAp, which contributes to the perturbation of the crystal lattice[89]. Lino et al found that the proliferation of BMSCs on polydiisopropyl fumarate (PCL-PDIPF) membrane containing 5% Sr was significantly higher than that on PCL-PDIPF membrane containing 1% Sr[90].…”

The Effect of Drug Heterogeneous Distributions within Core-Sheath Nanostructures on Its Sustained Release Profiles

“…In this nano era, more and more nanotechnologies are being introduced into pharmaceutics as new nanopharmaceutical methods [35][36][37][38][39][40]. All nano methods that are explored to prepare nanoparticles, nanofibers, and nanosheets can find their potential applications in creating new sorts of nano drug delivery systems [41][42][43].…”