Study On Interfacial Self-assembly And Emulsion Properties Of Alginate Derivatives Modified By Catechol Compounds

Sodium alginate is a natural renewable polymer polysaccharide with abundant resources,which is easy to modify,good biocompatibility and biodegradability,so as a carrier material can be widely used in the field of pesticide preparation and so on.Catecholol compound is a type of compound containing catechotic compounds,which can be used as adhesives,drug carriers,tissue stents and anti-stain coatings.This paper aims to combine the sodium alginate and catechins compounds by chemical modification to explore its self-assembly structure under different conditions in order to achieve the potential application in the new environmental pesticide preparation and porous support materials.Firstly,four dopamine-functionalized alginate derivatives Alg-DA-x(Alg-DA-5.3,Alg-DA-6.8,Alg-DA-8.3 and Alg-DA-9.8)with different p H regulation were prepared using sodium alginate and dopamine as raw materials through amide reaction and dopamine disproportionation reaction.The structure of Alg-DA-x was characterized by~1H NMR,FT-IR,UV,TGA and Gel permeation chromatography(GPC).The self-assembly behavior of Alg-DA-x was characterized by transmission electron microscopy(TEM)and laser particle size analyzer.The UV shielding performance of Alg-DA-x was investigated by UV irradiation.The results showed that Alg-DA-9.8 had excellent UV shielding performance.Finally,the dynamic contact Angle,wetting diameter and fluorescence loss rate of Alg-DA-x on leaf surface were investigated by optical contact Angle and fluorescence microscope.The results further show that Alg-DA-9.8 has good deposition and retention properties.Secondly,the emulsion(EAD-x)was prepared by Alg-DA-x stabilized liquid paraffin,and the stability of EAD-x was evaluated by multiple light scatterer and static emulsion method.Drug loading emulsion(AVM@EAD-x)was prepared by packaging a model drug avermectin(AVM)into EAD-x.The controlled release performance of AVM@EAD-x was investigated by drug packaging experiment,cumulative release experiment,UV light irradiation experiment,and dynamic contact Angle and wetting diameter of drug loading emulsion on leaf surface.Photodegradation resistance and deposition on leaf surface.The results show that AVM@EAD-9.8 has excellent encapsulation rate and can release AVM slowly in the release cycle.Among them,the AVM residue rates of AVM@EAD-5.3 and AVM@EAD-9.8 were less than 20%and 73.55±3.28%respectively after 48 hours of UV irradiation,both of which were higher than other drug-loaded emulsion samples.In addition,AVM@EAD-9.8 has the smallest dynamic contact Angle and the largest wettability on the blade,indicating that AVM@EAD-9.8 has excellent deposition performance on the blade surface.These results fully indicate that AVM@EAD-9.8has high encapsulation rate,controlled release property,drug photodegradation resistance and excellent deposition property on leaf surface.The multifunctional polymer material is expected to be used as a multifunctional drug delivery material in the field of drug delivery.Finally,the amphiphilic catechol-functionalized alginate derivative(Alg-CA)was prepared by Ugi reaction.The structure of Alg-CA was characterized by~1H NMR,FT-IR,UV and GPC.Dynamic light scatterometer(DLS)and transmission electron microscope(TEM)were used to investigate the self-assembly behavior of Alg-CA samples at p H 3,5,7 and 9 in aqueous solution.The results showed that the potential of the micelles increased first and then decreased with the increase of p H.By stabilizing dodecane samples with different p H to prepare Pickering emulsion with high internal phase,the influence of p H on the stability and properties of emulsion was investigated.The stability and rheological properties of the emulsion were measured by multi-gravity light scatterometer and rotary rheometer.The results showed that the stable high internal phase Pickering of Alg-CA self-assembled nanoparticles with p H=3 had high viscosity,good viscoelasticity and stability.In addition,the porous scaffolds were prepared by freeze-drying with four emulsions of different p H values,and the morphology of the porous scaffolds was studied by microscope and scanning electron microscope.The results showed that the pore size distribution of the porous scaffolds prepared by Alg-CA with p H=3 was the most uniform.