Adverse effects/ how can they be avoided?

The risk of adverse effects of implanted biomaterials is greatly increased, including allergy, chronic inflammation, collateral tissue damage, loss of function owing to immune responses, in fact, FBR is an adverse reaction from immune system.

Hard material

Take our magnesium alloy stent as an example. Normally, metal implants are designed to stay in the body permanently, but conditions such as late thrombosis, permanent physical irritation, release of toxic metal ions, and local chronic inflammation can cause serious effects leading to later reoperation.

Magnesium is favored because of its physical properties and good physiological compatibility. However, metals such as pure magnesium, which have poor mechanical properties, are also prone to corrosion over time after implantation, so they are not suitable. The magnesium alloy AZ31(aluminum 3%, zinc 1%) is a very good choice and has good biocompatibility. In order to ensure its performance, we can improve the performance by organic coating, ion injection, polymer coating and other methods. (Wang et al., 2021) Figure 9 can get some reflection.

Figure 12. a) Surface of AZ31 and b) is coated by PHB under the electron microscope. b) is smooth obviously and representatives more anti-corrosion. (Wang et al., 2021)

Soft material

Different physical/mechanical properties will reflect different reactions. A famous example is breast implants. There are a series of adverse outcomes of breast implants include: Implant complications, like pain and uncomfortable feelings, capsular contracture, connective tissue disease, breast cancer and reproductive problems and some others. Capsular contracture is an important problem, tightening of the tissue capsule around an implant, resulting in firmness or hardening of the breast and squeezing of the implant if severe (Center for Devices and Radiological Health, 2022). And in the past few decades that have been studied, in addition to always keep maintaining a rigorous attitude during operation to prevent be infected, irrigation with povidone-iodine and a triple antibiotic solution also reduced the risk of capsular contracture; recently a new class of drugs called leukotriene inhibitor has also been shown to reduce risk and even reverse capsular spasm, but is not suitable for people with liver disease. (Avoid capsular contracture (abnormally hard breasts) 2022)