Design And Preparation Of High-strength Antibacterial Hydrogels For Biological Applications

Due to the similar molecular structure and high hydrophilicity to biological macromolecules,hydrogels are widely used in biomedical and tissue engineering fields.When used as a biomedical material,the hydrogel needs to have sufficient mechanical strength,but also inhibit the growth of bacteria and avoid further infection of the wound.However,many hydrogels have the disadvantages of poor mechanical properties and weak antibacterial ability,and it is difficult to meet the requirements during application.Constructing a hydrogel with both high strength and excellent antibacterial ability has important practical guiding significance.In this work,two natural polysaccharides chitosan(CS)and heparin sodium(HS)with opposite charges were selected to prepare CS/HS hydrogels by solution-based self-assembly method.Under the synergetic effect of hydrogen bonding and electrostatic interaction,polysaccharide hydrogels have excellent mechanical properties,with tensile strength and elongation at break reaching 8.53 MPa and 133.7%,respectively.By changing the ionic strength and pH,the non-covalent interactions in the hydrogel network can be influenced to adjust the mechanical properties of the hydrogel.The dynamic reversible characteristics of non-covalent bonds make the hydrogel have excellent self-healing performance,with an efficiency of up to 80%.By changing the pH environment,the charge of the hydrogel surface can be adjusted to have strong adhesion to the charged surface.The use of metal ion coordination enhances the antibacterial activity of the hydrogel against E.coli.The hydrogel constructed from functionalized natural polysaccharides has excellent healing promotion ability and good biocompatibility(the cellular activity is up to 91.7%~94.3%).To construct a high-strength hydrogel with more efficient antibacterial activity,a temperature-sensitive high-strength hydrogel(TDN)loaded with antibacterial drugs was designed based on a double network strategy.Due to the effective energy dissipation mechanism,TDN hydrogels have excellent mechanical properties,tensile strength of 0.83 to 1.37 MPa,and elongation at break of 396.5% to 673.3%.The introduction of the functional monomer N-isopropylacrylamide(NIPAM)significantly enhances the temperature sensitivity of the hydrogel.As the NIPAM content increases to 62.5%,the low critical solution temperature(LCST)of the hydrogel can be reduced to 35.8 ℃,close to normal body temperature.The TDN hydrogel swells below the LCST and shrinks violently near the LCST,which can achieve a high-efficiency load on CV at 20 ℃(adsorption capacity of up to 2.19 mg/g)and rapid drug release at body temperature(release efficiency can reach 70.13% at 60 h).TDN hydrogel has high antibacterial activity and good biocompatibility(cellular activity is 89.6% to 91.2%),showing great potential as a biomedical wound dressing application.