## 4 Discussion
Biological tissues can produce reactive oxygen species during normal physiological processes; in addition, some environmental factors, such as ultraviolet radiation, gamma radiation, and environmental pollution, can induce production of reactive oxygen species. When the reactive oxygen species is generated, it can lead to oxidation damage to cell lipids, protein, and DNA. Once oxidative stress is induced, it in turn leads to the occurrence of a variety of tumors, atherosclerosis, rheumatoid, nervous system diseases, etc. Therefore, T-AOC detection of cells is particularly necessary. Compared with normal groups, the T-AOC of PBH-AZ31 had significant enhancement. Compared to other Mg alloys currently used as biosensor implant materials (such as ZX00, which contains 0.45% of Zn, 0.45% of Ca, and WE43, a rare earth Mg alloy containing up to 9% of yttrium, zirconium, and rare earth elements), AZ31 and PHB-AZ31 have been described to present improved corrosion resistance. Higher corrosion rates were observed [61] for rare-earth and lean Mg alloys compared to the AZ type; current-voltage curves and electrochemical impedance measurements confirmed that, for all Mg alloys, intermetallic particles acted as local cathodes; and more protective films were formed on the alloys' surface compared with pure Mg. The higher the presence of such intermetallic particles, the higher the corrosion resistance of the alloy. Mechanical, degradation, and osseointegration properties and the bone-implant interface strength of the AZ31 bioabsorbable magnesium alloy have been recently investigated [62; 63]. Despite the promising biocompatibility performance of ZX00 for bone-implant applications, these Mg alloys still need an investigation of the materials' mechanical performance, and no information on alloys' ability of fracture stabilization or load-bearing efficiency is available. To further make these materials suitable for deployment in osteosynthesis, adequate stability during fracture healing must be guaranteed [64]. Poly-hydroxy-alkanoates (PHAs), bio-polyesters such as PHB synthesized by many bacteria, have been produced in large quantities for several research fields, including medical applications [65]. It has been demonstrated by many studies that PHAs possess the required mechanical, biodegradable, and tissue-compatible properties for implant applications. PHAs' biodegradation by products such as oligomers and monomers has been verified to be nontoxic to cells and tissues. Mechanisms of PHA bioactivity for cell growth have also been described [66]. PHAs have been therefore largely demonstrated as suitable bioactive matrices to support bone tissue growth and attachment and proliferation of bone marrow cells. These cells on PHB scaffolds, in fact, have been described to present typical osteoblast phenotypes such as round cell shape, high alkaline phosphatase activity, strong calcium deposition, and fibrillar collagen synthesis, indicating that PHBs are suitable biomaterial for bone tissue regenerations from bone marrow cells [67]. Literature on biodegradation indicated that the degradation of Polyalkenoates (such as PHB) may be targeted to occur in controlled time spans from few weeks to one year depending on blend or copolymer composition and that it is accelerated by the presence of enzymes [68]. Although not investigated in our paper, the effect of alloying elements (comprising Al, Mn, Cu, and Ni) on biodegradability and biocompatibility is described in literature on dissolved immersion media testing for cytotoxicity, hemolysis, and platelet adhesion [69]. The results showed that none of the tested alloying elements appreciably impaired the viability of vascular smooth muscle cells except for Mn, which increased the viability of the ECV304 cell line. The hemolysis percentage of these Mg alloys was less than 5%, and no sign of thrombogenicity was observed [70].