Feasibility Study of Multi-Wavelength Optical Probe to Analyze Magnesium Implant Degradation Effects

Abstract

Near-infrared spectroscopy (NIRS) is a rapidly developing and promising technology with potential for spectrographic analysis. Understanding NIRS measurements on the implant-tissue interface for hydrogen gas formation as part of degradation is essential for interpreting the biodegradable Magnesium (Mg) based implants. This paper introduces novel NIR optical probe that can assess the state of Mg implant's degradation when in contact with biological tissues. A tissuemimicking phantom (TMP) to mimic biological tissue's optical properties helps investigate changes in reflectance spectra due to bubble formation at the implant-tissue interface. Spectra taken from different TMP samples containing biodegradable Mg and non-degradable Titanium (Ti) disk are suitable for evaluating the implant's interaction. The results show that the reflection in TMP for samples containing Mg disks, confirms the presence of hydrogen bubbles at the surface of implants. Multi-distance optical probe with depth selectivity of 3mm and 4mm has shown to be an effective tool to monitor bubble effect on different samples.

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

“…On average, the penetration depth of photons in the tissue is around 1/2 to 1/3 of the source-detector distance [ 41 ]. NIR light is estimated to reach a 3–3.5 mm depth, and the diffuse light is detected by the optical fiber inside the probe [ 29 , 42 ]. The same optical probe was recently used to validate the spectral absorption curves obtained from USPA [ 43 ].…”

“…The same optical probe was recently used to validate the spectral absorption curves obtained from USPA [ 43 ]. As shown in Figure 5 , we have used the molar extinction coefficient values to estimate the change in Hb and HbO 2 using an optical probe developed at Oslo Metropolitan University, Oslo, Norway [ 29 ]. In order to investigate different wavelengths, we must have DPF values for each wavelength.…”

“…The NIRS optical probe used for this experiment, which was developed at our lab at Oslo Metropolitan University, Oslo, Norway, has a source-detector distance of 8 mm. This specific value was chosen for a 3–3.5 mm penetration depth at the implant–tissue interface [ 29 ]. The optical light source of the probe operated in wavelengths between 650 and 1050 nm.…”

“…The proposed study uses a novel optical probe with wavelengths from 650 nm to 1050 nm that probes into the specific region of interest at the implant tissue interface non-invasively. In one of our previous studies, we provided detailed information on the optical probe’s feasibility for optical phantoms [ 29 ]. An NIR optical probe can provide valuable information about the absorption reflectance properties of tissues.…”

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

“…The PCA score plot for wavelength ranges from 1000 to 2000 nm is given in Figure 2 B, where more variation is observed in the Mg alloy as compared to the pure Mg and Ti. In a previous study, a tissue-mimicking gel prepared in the biochemistry lab at Oslo Metropolitan University, Norway, was used to investigate the effects of bubble formation in tissues, where we showed that the reflection of NIR light in the Mg alloy sample was 60% higher than the control one [ 46 ]. After each time point, disks were placed in the tissue-mimicking phantom to observe the reflection behaviour of bubbles in gels.…”