The growing need for reliable implantable orthopaedic devices has made the research in this area particularly important. Since the main reasons of implant failure are infections and lack of osteointegration, those two problems need to be addressed – this can be done by developing multifunctional coatings containing gallium and strontium, two elements with antibacterial and promoting osteointegration properties, respectively. In the first part of this work, various titanium alloy samples, either machined, sandblasted or plasma sprayed, have been treated with anodic spark deposition and the resulting coating has been analysed by SEM, ICP-OES and XPS. Adhesion, bending and microbiological tests have also been performed. The results have shown that the multifunctional coating developed during the work has excellent adhesive strength – able to withstand 82.96 MPa. It was also able to withstand flexural loads and present only small cracks, without delamination. It has been shown that in case of the plasma sprayed surfaces studied, the maximum gallium concentration in the electrolyte solution is 0.0015. The microbiological tests have shown that the antibacterial properties of gallium are not related to inhibitor release, but to the coating itself. The XPS analysis has proven the existence of the coating and has also shown excess of gallium ions on the coating compared to its concentration in the electrolyte solution. The ICP tests have shown that gallium and strontium release is stronger in acidic environments. The second part of the research was related to the masking of stem and acetabular pieces of hip prosthesis. It was observed that the masking technique used for the acetabulum was successful, whereas it was not possible to effectively isolate the stems – in this case, only silicone showed promising results. However, in order to isolate the stem properly, a custom-made silicon cover should be developed.
La crescente necessità di dispositivi ortopedici impiantabili affidabili ha reso la ricerca in questo settore particolarmente importante. Poiché i motivi principali del fallimento dell'impianto sono le infezioni e la mancanza di osteointegrazione, questi due problemi devono essere affrontati - questo può essere fatto sviluppando rivestimenti multifunzionali contenenti gallio e stronzio, due elementi con proprietà antibatteriche e promotori di osteointegrazione, rispettivamente. Nella prima parte di questo lavoro, vari campioni di leghe di titanio, sia lavorati, sabbiati o plasma spray, sono stati trattati col ASD e il rivestimento risultante è stato analizzato da SEM, ICP-OES e XPS. Sono stati eseguiti anche test di adesione, di flessione e microbiologici. I risultati hanno dimostrato che il rivestimento multifunzionale sviluppato durante il lavoro ha un'eccellente resistenza adesiva, in grado di resistere a 82,96 MPa. Era anche in grado di sopportare carichi di flessione e presentare solo piccole crepe, senza delaminazione. È stato dimostrato che nel caso delle superfici plasma spray studiate, la concentrazione massima di gallio nella soluzione elettrolitica è 0,0015. I test microbiologici hanno dimostrato che le proprietà antibatteriche del gallio non sono correlate al rilascio dell'inibitore, ma al rivestimento stesso. L'analisi XPS ha dimostrato l'esistenza del rivestimento e ha anche mostrato eccesso di ioni gallio sul rivestimento rispetto alla sua concentrazione nella soluzione elettrolitica. I test ICP hanno dimostrato che il rilascio di gallio e stronzio è più forte negli ambienti acidi. La seconda parte dello studio è stata correlata alla mascheratura degli steli e coppe acetabolari di protesi d'anca. È stato osservato che la tecnica di mascheratura utilizzata per l'acetabolo ha avuto successo, mentre non è stato possibile isolare efficacemente gli steli - in questo caso, solo il silicone ha mostrato risultati promettenti. Tuttavia, al fine di isolare correttamente lo stelo, dovrebbe essere sviluppata una mascheratura in silicone per ogni tipo di stelo.
Industrial scale-up of antibacterial electrochemical treatment for titanium alloy implantable orthopaedic devices
de OLIVEIRA FERREIRA, FELIPE;AL-NASRAWI, TAMER
2018/2019
Abstract
The growing need for reliable implantable orthopaedic devices has made the research in this area particularly important. Since the main reasons of implant failure are infections and lack of osteointegration, those two problems need to be addressed – this can be done by developing multifunctional coatings containing gallium and strontium, two elements with antibacterial and promoting osteointegration properties, respectively. In the first part of this work, various titanium alloy samples, either machined, sandblasted or plasma sprayed, have been treated with anodic spark deposition and the resulting coating has been analysed by SEM, ICP-OES and XPS. Adhesion, bending and microbiological tests have also been performed. The results have shown that the multifunctional coating developed during the work has excellent adhesive strength – able to withstand 82.96 MPa. It was also able to withstand flexural loads and present only small cracks, without delamination. It has been shown that in case of the plasma sprayed surfaces studied, the maximum gallium concentration in the electrolyte solution is 0.0015. The microbiological tests have shown that the antibacterial properties of gallium are not related to inhibitor release, but to the coating itself. The XPS analysis has proven the existence of the coating and has also shown excess of gallium ions on the coating compared to its concentration in the electrolyte solution. The ICP tests have shown that gallium and strontium release is stronger in acidic environments. The second part of the research was related to the masking of stem and acetabular pieces of hip prosthesis. It was observed that the masking technique used for the acetabulum was successful, whereas it was not possible to effectively isolate the stems – in this case, only silicone showed promising results. However, in order to isolate the stem properly, a custom-made silicon cover should be developed.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/149058