Lakhasly

5.With continuous Innovation in scientific research, new approaches, including gene delivery and the delivery of bioactive molecules such as growth factors, proteins, and peptides, are being developed. Currently, other tissue engineering scaffolds such as calcium phosphates and composite materials (eg, hydroxyapatite, ?-tricalcium phosphate, and whitlockite) for bone tissue engineering and amniotic membranes for corneal tissue engineering are under research.69,77 Skin tissue engineering scaffolds can be categorized as porous, fibrous, microsphere, hydrogel, composite, and acellular materials.73 Typically, natural biomaterials and their derivatives are biodegradable, absorbable, and harmless to the body, but their strength and processing performance are poor and their degradation speed cannot be controlled.These include natural polymers (chitosan, hyaluronic acid, and collagen), nanocomposite scaffolds (eg, nanobioactive glass and metal NPs), and conducting polymers (eg, polyaniline, polypyrrole, and polythiophene).73-75 Taghiabadi et al synthesized an intact amniotic membrane-based scaffold for cultivating adipose-derived stromal cells (ASCs).By ASCs on an acellular human amniotic membrane (HAM), they created a neoteric skin substitute.76 Zhang et al designed a conductive and antibacterial hydrogel based on polypyrrole and functionalized Zn-chitosan molecules for the management of infected chronic wounds.Hence, in order to improve the mechanical and biological properties of scaffolds (eg, adhesion, strength, processing performance, and degradation speed) and accelerate wound healing, composite scaffolds have been developed by combining the characteristics and advantages of different materials.In contrast, synthetic biomaterials, such as polyethylene glycol (PEG) nano-scaffolds, show more stable structural properties and can be chemically modified.Depending on their constituents, these composite scaffolds can achieve specific functions.

5. Appropriate wound healing environment: The scaffold system should be able to absorb the wound exudate and
   prevent wound dehydration, reducing surface necrosis on the wound.63,64
   Scaffold systems can be classified as follows based on the source and function of the materials.
   Source of Materials
   When designing scaffold systems for chronic wound, an appropriate matrix source needs to be selected. Table 1 lists
   a few sources of nanocomposites used in wound dressing. Natural nanomaterials and their derivates have good
   biocompatibility and can be degraded by enzymes or water. However, their characters and quality differ from batch to
   batch and cannot be standardized. In contrast, synthetic biomaterials, such as polyethylene glycol (PEG) nano-scaffolds,
   show more stable structural properties and can be chemically modified. However, the biosafety of synthetic materials
   needs to be strictly examined.
   Function of Materials
   According to their functions, tissue engineering materials can be used for bones, nerves, blood vessels, skin, and other
   tissues (eg, tendon, ligament, cornea, liver, and kidneys).
   Tissue engineering scaffolds for the skin can be of several types. These include natural polymers (chitosan, hyaluronic
   acid, and collagen), nanocomposite scaffolds (eg, nanobioactive glass and metal NPs), and conducting polymers (eg,
   polyaniline, polypyrrole, and polythiophene).73–75 Taghiabadi et al synthesized an intact amniotic membrane-based
   scaffold for cultivating adipose-derived stromal cells (ASCs). By ASCs on an acellular human amniotic membrane
   (HAM), they created a neoteric skin substitute.76 Zhang et al designed a conductive and antibacterial hydrogel based on
   polypyrrole and functionalized Zn–chitosan molecules for the management of infected chronic wounds. They demonstrated
   the promising potential of the hydrogel in promoting the healing of the infected chronic wound after electrical
   stimulation. Currently, other tissue engineering scaffolds such as calcium phosphates and composite materials (eg,
   hydroxyapatite, β-tricalcium phosphate, and whitlockite) for bone tissue engineering and amniotic membranes for corneal
   tissue engineering are under research.69,77
   Skin tissue engineering scaffolds can be categorized as porous, fibrous, microsphere, hydrogel, composite, and
   acellular materials.73 Typically, natural biomaterials and their derivatives are biodegradable, absorbable, and harmless
   to the body, but their strength and processing performance are poor and their degradation speed cannot be controlled.
   Hence, in order to improve the mechanical and biological properties of scaffolds (eg, adhesion, strength, processing
   performance, and degradation speed) and accelerate wound healing, composite scaffolds have been developed by
   combining the characteristics and advantages of different materials. Depending on their constituents, these composite
   scaffolds can achieve specific functions. Currently, most novel scaffolds being developed use composite materials to
   obtain multifunctional characteristics.
   Delivery Systems
   Delivery systems are used to deliver drugs, cells, genes, and other neoteric bioactive molecules to the body or target area
   via transplantation or injection.78 Traditionally, delivery systems are broadly divided into two categories, drug delivery
   and cell delivery. With continuous Innovation in scientific research, new approaches, including gene delivery and the
   delivery of bioactive molecules such as growth factors, proteins, and peptides, are being developed.
   Recently, there has been a significant increase in new biotechnology-based treatments, among which cell and gene
   therapies are quite sophisticated. Exosomes have shown superior therapeutic potential against various conditions, a