The effect of enzymes on the in vitro degradation behavior of Mg alloy wires in simulated gastric fluid and intestinal fluid

Abstract

With an upsurge of biodegradable metal implants, the research and application of Mg alloys in the gastrointestinal environment of the digestive tract have been of great interest. Digestive enzymes, mainly pepsin in the stomach and pancreatin in the small intestine, are widespread in the gastrointestinal tract, but their effect on the degradation of Mg alloys has not been well understood. In this study, we investigated the impacts of pepsin and pancreatin on the degradation of Mg-2Zn alloy wires. The results showed that the pepsin and pancreatin had completely different even the opposite effects on the degradation of Mg, although they both affected the degradation product layer. The degradation rate of Mg wire declined with the addition of pepsin in simulated gastric fluid (SGF) but rose with the addition of pancreatin in simulated intestinal fluid (SIF). The opposite trends in degradation rate also resulted in completely different degradation morphologies in wires surface, where the pitting corrosion in SGF was inhibited because of the physical barrier effect of pepsin adsorption. In contrast, the adsorption of pancreatin affected the integrity of magnesium hydrogen phosphate film, causing a relatively uneven degraded surface. These results may help us to understand the role of different digestive enzymes in the degradation of magnesium and facilitate the development and clinical application of magnesium alloy implanted devices for the digestive tract.

Effects of Different Concentrations of BSA on In Vitro Corrosion Behavior of Pure Zinc in Artificial Plasma

“…The band at around 1265 cm –1 could be attributed to amide III vibration, which could be the association of C–O stretching of hydroxyl groups of BSA. , The peak of amide II (N–H bending and C–N stretching) of CONH was detected at 1530 cm –1 , and peaks at 1645 cm –1 were associated with the bending vibration of CO of amide I of organic molecules absorbed on the surface . The peak at 2935 cm –1 was related to stretching vibrations of the C–H groups of BSA and might also belong to HPO 4 . − The peak at 3433 cm –1 arose from the −NH 2 group, which also be attributed to the stretching vibration of the O–H group. , The presence of the above groups indicates that the BSA molecules are adsorbed on the surface of the material …”

“…2−8 The peak at 3433 cm −1 arose from the −NH 2 group, which also be attributed to the stretching vibration of the O− H group. 36,38 The presence of the above groups indicates that the BSA molecules are adsorbed on the surface of the material. 36 3.3.…”

A biodegradable magnesium surgical staple for colonic anastomosis: In vitro and in vivo evaluation

“…Thus, only 0.3 mm of the clinical Ti staple diameter brings a challenge between the tissue joining with the degradation time of devices if we use Mg alloys instead. Recently, with the improvement of Mg alloy processing technology, using Mg alloys in the gastrointestinal tract has attracted attention again [ [17] , [18] , [19] ]. Implanting the Mg–6Zn (wt.%) pins in Sprague-Dawley rats' cecum and the high-Purity magnesium (HP–Mg) staples in transgenic mice rectal demonstrated the Mg degradation could suppress the inflammatory response compared to the medical Ti alloy [ [20] , [21] , [22] ].…”

“…On the one hand, unlike the body fluid and blood environment, the gastrointestinal tract belongs to the external environment of the human body. Its internal environment varies with the different digestive functions of each part, including the pH value, ion balance, enzymes, and so on [ 13 , 14 , 17 , 18 ]. Moreover, the anastomotic approach also affects the service environment of the implanted staple.…”

“…Due to the lack of research on medical magnesium alloys at that time, AZ31 alloy with good strength and plasticity but containing Al was selected as the material for making staples. This has been improved in our subsequent studies, with our in-depth research on the preparation technology of magnesium alloy wires [ 17 , 18 , 25 , 26 ]. To date, even though some progress has been made in the application of magnesium alloys in the gastrointestinal tract, people still lack confidence in magnesium alloys as anastomotic staples, especially in their mechanical properties, due to the lack of a large number of reports on large animal experiments.…”