Absorbable implants made of magnesium alloys may revolutionize surgical intervention, and fine magnesium wire will be critical to many applications. Functionally, the wires must have sufficient mechanical properties to withstand implantation and in-service loading, have excellent tissue tolerance, and exhibit an appropriate degradation rate for the application. Alloy chemistry and thermomechanical processing conditions will significantly impact the material's functional performance, but the exact translation of these parameters to implant performance is unclear. With this in mind, fine (127 µm) WE43B magnesium alloy wires in five thermomechanical process (TMP) conditions (90% cold work [CW], and 250, 375, 400, and 450°C heat treatments) were investigated for their effect on mechanical and corrosion behavior. The TMP conditions gave clear metallurgical differences: transverse grain dimensions ranged from 200 nm (CW) to 3 µm (450°C), UTS varied from 324 MPa (450°C) to 608 MPa (250°C), and surgical knotting showed some were suitable (CW, 400°C, 450°C) while others were not (250°C, 350°C). In vitro and in vivo corrosion testing yielded interesting and in some cases conflicting results. After 1 month immersion in cell culture medium, wire corrosion was extensive, and TMP conditions altered the macrocorrosion morphology but not the rate or total release of magnesium ions. After 1 month subdermal implantation in mice, all wires were well tolerated and showed very little corrosion (per µCT and histology), but differences in localized corrosion were detected between conditions. This study indicates that WE43B wires treated at 450°C may be most suitable for surgical knotting procedures. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1987-1997, 2018.

Due to its numerous applications in the field of metallurgy and its role as an alloying element for slowing down the biodegradation of pure magnesium typically known to have very low corrosion resistance, the need to develop simple and inexpensive methods for determination of cerium is important. Ce3+ was determined by cathodic stripping voltammetry (CSV) using Osteryoung square‐wave voltammetry (OSWV) for the stripping step. Indium tin oxide (ITO) was used as the working electrode because of its very good positive potential range with smooth background current. Under optimized conditions, the calibration plot was linear in the concentration range of 100 nM to 700 nM Ce3+. A calculated detection limit of 5.8 nM was found for a 5 min deposition time at ITO based on the 3σ method. Interference from selected metal ions was also examined, and no significant interferences were observed. The good selectivity of this sensor makes it a good candidate for practical applications such as monitoring Ce3+ released into solution during the biodegradation of Mg−Ce alloys being developed for resorbable biomedical implants.

1Introduction tested whether ac onductivity sensor could be used to monitor Mg degradation by detecting changes in ionic strength in real time,i nt hree physiologically appropriate fluids (a sodium chloride solution, phosphate buffered saline and ac ell culture medium maintained under the standard conditionsu sed for mammalian cell culture).Here we demonstrate that an electrochemical conductivity sensor, in combination with ap Hs ensor,r ecorded very different patternso fr eal-timec hanges in the ionice nvironmentc reated by Mg immersion and degradation in the three modele lectrolyte solutions,o ver a4 8-hour time period.

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Spectroelectrochemical sensors combine electrochemistry, spectroscopy, and partitioning into a film to provide improved selectivity for the target analyte. The sensor usually consists of an optically transparent electrode (OTE) coated with a charge selective polymer film. The polymer film is chosen to pre-concentrate analyte at the OTE surface to improve the sensitivity and provide selectivity against like charged interferences. OTEs such as Indium Tin Oxide (ITO) have been used extensively for spectroelectrochemical sensors, but little is known about the applicability of such sensors using other OTE materials, such as Boron Doped Diamond (BDD). One distinct advantage of BDD OTEs over ITO OTEs is their significant increase in sensitivity for organic compounds, such as 4-aminophenol and hydroquinone. We have developed absorption and fluorescence-based sensing methods with a BDD OTE coated with a sulfonated ionomer film, Nafion