Surface-transformed osteoinductive polyethylene terephthalate scaffold as a dual system for bone tissue regeneration with localized antibiotic delivery.

Abstract

Multifunctional scaffolds have recently attained superior significance in tissue regeneration due to combinational activity profile that is usually accomplished by separate sequential therapy. Here, we present a dual system comprised of surface-phosphorylated PET fibrous matrix coated with ciprofloxacin-impregnated biodegradable polymer poly (hydroxyethyl methacrylate) aiming at regeneration of bone tissue deprived of bacterial infections, particularly osteomyelitis. The ATR, XPS and FESEM/EDX results provided confirmative evidences for surface phosphorylation of PET and in situ coating of the polymer. Swelling and contact angle measurements demonstrated improved hydrophilicity which is further corroborated by in vitro degradation profile in PBS. Preliminary evaluation by MTT and actin staining proved its biocompatibility while enhanced in vitro mineralization in 1.5X SBF by FESEM/EDX clearly indicate the primary nucleation and secondary growth of beautiful apatite crystals with Ca/P ratio similar to human bone. Alizarin red S and von Kossa staining validated the biomineralization in MG-63 cells. The sequential expression of early and late biomarkers -alkaline phosphatase (ALP) and osteocalcin (OSN)- of osteoblast differentiation in rat bone marrow mesenchymal cells (BMC) has demonstrated osteoinductive nature of the system. The second functionality of the scaffold has been proven by step-wise ciprofloxacin-release profile (in vitro) with ~60% release within 120h. In addition, antibacterial studies of ciprofloxacin- eluted from the scaffold have shown apparent zones of inhibition against Staphylococcus aureus (3.6±0.3cm) and Escherichia coli (3.0±0.8cm). Hence, the surface-transformed PET scaffold function as a dual system as localized antibiotic delivery vehicle against bone infections and undergo self-biomineralization leading to osteoinduction.