Study On Preparation And Properties Of Catechol-Base Adhesive

Surgical wound suture will cause secondary pain and wound infection.Development of medical adhesives can avoid the problems.However,the biological adhesives on the market such as aldehydes and fibrinics might cause toxicity and lead to blood-borne diseases,infection and allergies.Therefore,it is very necessary to develop a medical adhesive with non-formaldehyde composition,high adhesion even in wet condition,and excellent biocompatibility and biodegradation.Mussel can adhere to the substrate's surfaces even in wet condition,which is contributing to the catechol group.By inspiring the adhesion property of the mussels,catechol groups were employed to modify bio-polymers to prepare a serial of novel and non-toxic biomedical adhesion agents.Biomacromolecules such as hyaluronic acid(HA)and ?-polyglutamic acid(?PGA)were firstly activated by 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride(EDC)and N-hydroxysuccinimide(NHS).Dopamine(DA)containing catechol group was grafted to the HA and ?PGA chains,by amidation reaction,respectively.The product structure and the grafting rate of DA were characterized by Fourier transform infrared spectroscopy(FTIR),ultravioletvisible spectr-ophotometer(UV-Vis)and proton nuclear magnetic resonance spectroscopy(1H NMR).The tensile shear strengths of these samples with aluminum plates(Al),phenolic resin plates(PF)and polyurethane(PU)were tested by the tensile test,comparing the tensile shear strength of the samples with different grafting degrees.The effects of sample concentration,ambient temperature and curing time on the tensile strength of HA-DA and ?PGA-DA with PF were measured by tensile testing machine.The polymer adhesion agents could be crosslinked by addition of KMn O4,FeCl3 and NaIO4 in order to prevent the sample from running off in the wet environment of the body.The minimum concentration of the reagentand the gelation rate of the sample were tested by rheometer.Tensile strength between HA-DA and PF with additional different oxidants was detected,and the best oxidant was selected to crosslink the ?PGA-DA adhension.Pig skin could be simulated the human skin in adhesive test.Swelling and degradation property of the two samples were studied.Cell viability can be calculated by MTT assay and the number of cells was observed by fluorescence microscopy.The results showed that both of them have good adhesion properties to the three plates,especially with PF.HA-DA and ?PGA-DA could be easily oxidative crosslinking by Na IO4 to form gelation,and strength between adhension and PF was best.Strength upon pig skin also could be enhanced by NaIO4 and the maximum strength was 25.94 kPa.Mild swelling and slow degradation were beneficial to the recovery of skin and other tissue.Biocompatibility was check by MTT assay with high cell survival rate.In order to change the gelation mechanism and decrease the dependence to NaIO4 in gelation,3,4-dihydroxy benzenepropanoic acid(DPA)containing catechol group was activated by EDC and NHS amidation reaction.DPA was grafted to chitosan(CS)chains by amidation reaction.The product structure and the grafting degree of DPA were characterized by FTIR,UV-Vis and 1H NMR.The strengths between CS-DPA and Al,PF and PU were tested by the tensile test,and the effect of concentration on the strength was measured.CS-DPA with optimum concentration was selected as the cationic component and ?PGA-DA was used as the anionic component.CS-DPA/?PGA-DA gel could be prepared by electrostatic interaction by mixing CS-DPA and ?PGA-DA in suitable pH buffer.Swelling and degradation properties were tested and the gelation was checked by rheometer.Strength of CS-DPA/?PGA-DA with different proportions of CS-DPA and ?PGA-DA upon PF was tested by tensile testing machine.Strength of CS-DPA/?PGA-DA upon PF was tested in different temperature.Strength of sample upon pig skin and porcine cartilage was tested.Biocompatibility of CS-DPA/?PGA-DA was also investigated.The experimental results showed that there was the tensile strength between CS-DPA and three plates.The strength was proportional to the grafting degree of DPA.Strength between CS-DPA/?PGA-DA and PF was excellent and the maximum strength was 0.38 MPa.Strength could be affected by the change of temperature and time.The maximum strength of CS-DPA/?PGA-DA upon pig skin was 22.5 kPa and sample upon porcine cartilage was 145.34 kPa,which was 18 times of commercial fiber adhesive.Biocompatibility was check by MTT assay and the survival rate of L929 cells was above 90 %.The medical bio-adhesives with excellent strength and biocompatibility were fabricated by biomacromolecules as main materials and catechol as functional group.The obtained bio-adhensives have the potential application in the fields of surgery and tissue repairing area.