Self-assembling antimicrobial peptides on nanotubular titanium surfaces coated with calcium phosphate for local therapy

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.Bacterial infection is a serious medical problem leading to implant failure. The current antibiotic based therapies rise concerns due to bacterial resistance. The family of antimicrobial peptides (AMP) is one of the promising candidates as local therapy agents due to their broad-spectrum activity. Despite AMPs receive increasing attention to treat infection, their effective delivery to the implantation site has been limited. Here, we developed an engineered dual functional peptide which delivers AMP as a biomolecular therapeutic agent onto calcium phosphate deposited nanotubular titanium surfaces. Dual functionality of the peptide was achieved by combining a hydroxyapatite binding peptide-1 (HABP1) with an AMP using a flexible linker. HABP functionality of the peptide provided a self-coating property onto the nano-topographies that are designed to improve osteointegration capability, while AMP offered an antimicrobial protection onto the implant surface. We successfully deposited calcium phosphate minerals on nanotubular titanium oxide surface using pulse electrochemical deposition (PECD) and characterized the minerals by XRD, FT-IR, FE-SEM. Antimicrobial activity of the engineered peptide was tested against S. mutans (gram- positive) and E. coli (gram-negative) both in solution and on the Ca-P coated nanotubular titanium surface. In solution activity of AMP and dual functional peptide have the same Minimum Inhibitory Concentration (MIC) (32 mg/mL) against E.coli. The peptide also resulted in the reduction of the number of bacteria both for E.coli and S.mutans compare to control groups. Antimicrobial features of dual functional peptides are strongly correlated with their structures suggesting tunability in design through linkers regions. The dual-function peptide offers single-step solution for implant surface functionalization that could be applicable to any implant surface having different topographies.NIH AR062249–03NIH R01DE025476–01TUBITAK BIDEP 2218ITU Institute for Graduate Program

Alkaline and acidic anodization of titanium implants using electrochemistry

18th National Biomedical Engineering Meeting (BIYOMUT) -- OCT 16-17, 2014 -- Istanbul, TURKEYRecent advancements in the medical field has lead to the prolongation of life expectancy and an increase in the elderly population. Consequently, the deterioration of bone health and a shift towards carbohydrate-based dietary habits has lead to an increase in tooth loss and thus to an increase in the use of titanium implants. Titanium and alloys due to their inherent properties such as biocompatibility, corrosion resistance, lower elastic modulus and high strength are preferred in the manufacture of orthopedic and dental implants. There are studies conducted on the further improvement of its medical properties through the development of new manufacturing methods. In this study, improvement of the biocompatibility of Titanium implants by surface etching, functionalization and hydroxyapatite coating has been investigated. Titanium implants been have electrochemically acid-etched using sulphuric and hydrochloric acid, anodized in potassium oxide solution and hydroxyapatite coated in SBF at room temperature

Silkfibroin-Ca-P Composite Bone Replacement Material for Guided Bone Growth

20th International Conference on Composite Materials (ICCM) -- JUL 19-24, 2015 -- Copenhagen, DENMARKMineralized natural protein based materials are investigated as novel materials to be used in tissue engineering and as bone replacement materials. Silk fibroin fiber based foams and films are used as mineralized composites due to their excellent biocompatibility. In this study, the biomimetic mineralization of orderly oriented fibrous silk based scaffolds was studied. Commercially obtained pure silk woven fabric was boiled in 0.02 M Na2CO3 for 20 min. The deposition of calcium phosphate was conducted at 37 degrees C for twenty minutes in seven sequential immersion steps in 250 mM CaCl2 2H(2)O and 120 mM K2HPO4, both containing 0.15 M NaCl and 50mM solution of TRIS-HCl, buffered at 7.4. Ca-P deposit on the samples increased with the number of immersion steps. The analysis of the Ca-P powder deposit indicated formation of brushite with its characteristic peak at around 11.76 2 theta using the XRD and at 1000, 3000-3500 cm(-1) using the FTIR analyses. Samples were sputter coated with gold for SEM characterization. The morphology of the Ca-P deposits confirmed formation of brushite crystals, which were then transformed into HA using electrochemical hydrothermal treatment in concentrated SBF solution 40 degrees C at a current density of -25mA/cm(2) for 60 min. HA formation was confirmed using XRD, FTIR and SEM analysis. The deposition and electrochemical conversion of brushite to hydroxyapatite on silk, thus forming a silk-HA composite material may be an inexpensive promising biocompatible graft material to be used in bone replacement surgery, where highly oriented materials for guided cell growth may be needed