In Vitro Monitoring of Magnesium-Based Implants Degradation by Surface Analysis and Optical Spectroscopy

Abstract

Magnesium (Mg)-based degradable alloys have attracted substantial attention for tissue engineering applications due to their biodegradability and potential for avoiding secondary removal surgeries. However, insufficient data in the existing literature regarding Mg’s corrosion and gas formation after implantation have delayed its wide clinical application. Since the surface properties of degradable materials constantly change after contact with body fluid, monitoring the behaviour of Mg in phantoms or buffer solutions could provide some information about its physicochemical surface changes over time. Through surface analysis and spectroscopic analysis, we aimed to investigate the structural and functional properties of degradable disks. Since bubble formation may lead to inflammation and change pH, monitoring components related to acidosis near the cells is essential. To study the bubble formation in cell culture media, we used a newly developed Mg alloy (based on Mg, zinc, and calcium), pure Mg, and commercially available grade 2 Titanium (Ti) disks in Dulbecco’s Modified Eagle Medium (DMEM) solution to observe their behaviour over ten days of immersion. Using surface analysis and the information from near-infrared spectroscopy (NIRS), we concluded on the conditions associated with the medical risks of Mg alloy disintegration. NIRS is used to investigate the degradation behaviour of Mg-based disks in the cell culture media, which is correlated with the surface analysis where possible.

A Novel PLLA/MgF2 Coating on Mg Alloy by Ultrasonic Atomization Spraying for Controlling Degradation and Improving Biocompatibility

“…Meanwhile, the degradation of Mg alloy led to another two changes: one is the release of ions and hydrogen to liquid and a change in pH; another is the change in element composition, which is shown in Figure 9 and Figure 10 . Mg alloy can cause a rise in liquid pH [ 52 ]. The dense MgF 2 coating reduced the contact between the Mg alloy and the liquid, thus reducing the degradation and lowering the pH.…”

In Vivo Analysis of a Biodegradable Magnesium Alloy Implant in an Animal Model Using Near-Infrared Spectroscopy

“…The primary goal of the in vitro study was to check the feasibility of using variations in the optical spectrum as a response to changes in the surrounding medium caused by the degradation of magnesium implants with time. The experiment used the transmission-type optical data collection [ 25 ], as illustrated in Figure 2 b. The experiment used three samples of biodegradable Mg alloy ZX00 disks [0.45 wt% Zn—0.45 wt% Ca.…”

“…The selected time points were chosen considering the critical pH variations in the surrounding region of the implant during the first two weeks [ 25 ] and physiological meaning. The first two weeks are determinant for the success of implant osseointegration, and it is when soft tissue surrounding the implant heals.…”

Near-Infrared Spectroscopy for the In Vivo Monitoring of Biodegradable Implants in Rats

“…Near-infrared spectroscopy (NIRS) technology enables the measurement of oxygen delivery, pH, and blood flow in tissues, which can be used to assess metabolic and respiratory health [ 14 , 15 , 16 , 17 ]. NIRS and partial least square regression (PLSR) can be applied to estimate the change in pH values in vivo and in vitro, as discussed in our previous studies [ 18 , 19 ].…”

“…However, because the Hounsfield Unit (HU) of Mg alloys is similar to the bone structure, it is challenging to differentiate the Mg particles from bone tissue using microCT [ 22 , 23 ]. Therefore, NIRS can analyze Mg degradation’s effects, regardless of it having the same HU unit as bone, and in vitro studies have evaluated this degradation effect [ 19 ]. A device must be developed to be used in in vivo clinical procedures that can also be used in real-life scenarios to monitor the Mg alloy’s degradation effect.…”