Fabrication and characterization of antibacterial Polycaprolactone and natural Hydroxyapatite nanofibers for bone tissue scaffolds

Abstract

Chronic osteomyelitis is a bone infection that may result in pain, pus, bone resorption and damage, and fractures. The disease often needs prolonged antibiotic therapy, and in many cases severe wounds and bone voids are caused by surgical interventions. Autograft, allograft, xenograft, or synthetic materials have been used as bone fillers or scaffolds. Gentamicin is a common antibiotic in osteomyelitis treatment; including gentamicin in the scaffold therefore would help treat the osteomyelitis once the scaffold is in place and help prevent spreading of the disease. Hydroxyapatite (HA) is a mineral that is naturally found in bone that has osteoconductive properties in bone tissue engineering. I hypothesize that a bone graft substitute incorporating both gentamicin and HA would be very beneficial for the treatment of osteomyelitis with large bone damage. While there are many methods to fabricate porous graft using a biodegradable polymer, electrospinning technique is particularly ideal due to nano-fibrous structure resembling the extracellular matrix of bone. The objectives of my thesis work are to develop a gentamicin-contained PCL-HA composite scaffold and to evaluate its therapeutic efficacy in inhibiting E. coli growth using at in vitro settings. PCL-HA composite nanofibers were fabricated using electrospinning with inclusions of gentamicin to give the nanofibers antibacterial properties. HA was obtained from cow bone, with SEM and EDS examinations confirming that its chemical structure and size were well suited to promote bone growth. SEM micrographs illustrated the nano-scaled fiber structures with an average diameter of 142.2 nm, and biological tests revealed that the gentamicin-containing PCL-HA nano-fiber membranes effectively exterminated E. coli's growth up to 7 days, with zones of inhibition to 4 cm2. Further study is warranted to characterize the antibiotic release patterns in vivo and the potential safety issues.