# Bio-Sourced and Biodegradable Membranes
## 4 Green Membrane Technology Applications
### Biomedical Applications  
Bio-inspired and biodegradable membranes have been gaining increasing attention for their potential applications in biomedical fields, including tissue engineering (dental implants, rebuilding of bone, artificial skin, liver, nerve, etc.), drug delivery, and hemodialysis/hemoglobindafiltration due to their low toxicity, osteoconductivity, antibacterial properties, physical/mechanical properties, formability, versatility with multiple functions, and sterilization capability [9; 216; 217; 218; 219; 220; 221]. The main purpose of tissue engineering is to recover or replace damaged body tissues and organs [217]. A variety of bio-inspired materials are being investigated for use in tissue engineering. Biodegradability, bioavailability, and bioactivity of chitosan make it a highly biocompatible biopolymer suitable for use in a variety of biomedical applications [222]. Chitosan and chitin-based materials are commonly used in tissue engineering in a variety of physical forms since they are capable of accelerating the wound healing by providing the tissue cells with an extracellular microenvironment [9; 223; 224; 225]. [PERSON] et al. [225] prepared a biodegradable chitosan-based film and used it to stimulate the wound healing process and repair the injured skin. The results of their research demonstrated that the prepared chitosan/agarose film has all the required characteristics to be served as an artificial skin substitute. Biodegradable membranes have also exhibited to be promising candidates for drug delivery systems and improving the treatment efficiency [216; 217; 226]. Obtaining therapeutic effects in host cells requires control of the dose and localization of drug release by preparing the porous materials with relevant size scales (nanometer for small molecules to a few tens of nanometer for macromolecules' delivery). In this regard, [PERSON] and [PERSON] [226] used the template etching method to prepare a nanoporous membrane for drug delivery purposes using the poly(caprolactone) (PCL) biodegradable polymer. For the diffusion experiment, they employed sodium fluorescein (SFC) as the small molecule (\(\sim\)1 nm) and fluorescein isothiamate-labelled bovine serum albumin (FITC-BSA) as the macromolecule (\(\sim\)7 nm). FC and FITC-BSA released at a normal first-order diffusion (exponential release) and zero-order (constant release), respectively. The thin film porous PCL membrane fabricated in this study was found to be useful in flexible therapeutic devices. Hemodialysis is another process in which membranes are used to remove blood toxins. Conventional membranes have been widely used for hemodialysis; however, their hydrophobic nature could negatively affect their biocompatibility and cause blood clotting [178; 227]. Cellulose based membranes with high hydrophilicity are still used for HD membranes production, despite of development of other types of polymeric materials for biomedical applications [168; 228]. PES is still the most spread polymer for HM membrane fabrication, though its surface modification is required to improve its hemocompatibility [229; 230]. Table 1 presents further studies on biomedical applications of biodegradable membranes.