Preparation,Properties And Application Of N-Hydrophobic-O-Carboxymethyl Chitosan

Chitosan,the most abundant alkaline polysaccharide in nature and the second most abundant biopolysaccharide after cellulose,has good biocompatibility,biodegradability and antibacterial properties,and has a wide range of potential applications in biomedicine,food packaging,wastewater treatment,textile printing and dyeing,and cosmetics.This thesis is divided into two parts,one part prepared an amphiphilic chitosan:N-lauric acid-O-carboxymethyl chitosan（LA-CMCh）by accessing lauryl chain segment on-NH₂ as raw material,and investigated the basic properties of this chitosan derivative and applied it to drug delivery.In the second part,calcium carbonate nanoparticles were prepared with N-（2-hydroxy）propyl-3-trimethylammoniumchitosanchlorideand carboxymethylcellulose modulation,and N-（2-hydroxy）propyl-3-trimethylammonium chitosan chloride/carboxymethylcellulose/calcium carbonate films were prepared with calcium carbonate as in situ additives,and the effect of calcium carbonate on the properties of chitosan/carboxymethylcellulose based films was investigated to reveal the effect mechanism on the film properties.The main contents are as follows:An amphiphilic chitosan derivative,N-lauric acid-O-carboxymethyl chitosan（LA-CMCh）,was prepared from O-carboxymethyl chitosan and lauric acid（LA）by acylation reaction.The successful synthesis was confirmed by ¹H NMR and FTIR,and the optimum reaction conditions were determined:the reaction time was 6h,the reaction temperature was 80℃,the ratio of-COOH to-NH₂ was 3:1,and the degree of substitution was 13%.XRD and TGA patterns show that the crystallinity and initial decomposition temperature of LA-CMCH decrease due to the introduction of LA,but the highest decomposition temperature increases.LA-CMCh is self-aggregating and its critical aggregation concentration depends on the degree of substitution of lauric acid groups and the p H of the solution.LA-CMCh aggregate can load curcumin up to 21.70%,and release the largest amount of curcumin at p H 5.52,and release 14.79%within 6 hours.LA-CMCh has good antibacterial activity against both Escherichia coli and Staphylococcus aureus and is a good raw material as an oil-soluble drug nanocarrier.Carboxymethyl cellulose（CMC）-based orally disintegrating films were prepared with LA-CMCh and N-（2-hydroxy）propyl-3 trimethyl chitosan ammonium chloride（HTCC）as additives,and were used for oral administration of lomefloxacin hydrochloride.The effects of additives on CMC orally disintegrating film were studied by cross-sectional morphology,mechanical properties,thermodynamic properties,antibacterial properties,disintegration time and in vitro release of lomefloxacin hydrochloride.SEM images show that CMC/HTCC films have smooth and uniform cross-sectional morphology,but the cross-section of CMC/HTCC/LA-CMCh films has many bumps.The addition of HTCC and LA-CMCh does not affect the thermodynamic properties of the films,but it will improve the mechanical properties of the films.The tensile strength increased from 2.92MPa to 6.83MPa,and the elongation at break increased from 28.41%to 39.56%.The addition of HTCC and LA-CMCh makes the film antibacterial,and its antibacterial effect on Escherichia coli is weaker than that of Staphylococcus aureus.All films have a fast disintegration time（<60s）,the fastest is42.16s.Moreover,all CMC-based films have the characteristics of rapid drug release,which can reach more than 80%in 10 minutes.This shows the application prospect of this CMC-based film in oral administration.N-（2-hydroxy）propyl-3-trimethyl chitosan ammonium chloride（precursors of amphiphilic chitosan）/carboxymethyl cellulose（HTCC/CMC）was used to control the synthesis of micro-nano calcium carbonate,and the HTCC/CMC/calcium carbonate film was prepared by using this calcium carbonate as an in-situ additive.The effects of HTCC/CMC on the morphology,crystal form,particle size and distribution of calcium carbonate particles,and the effects of in-situ crystallization of calcium carbonate particles and content on the microstructure and calcium carbonate film were studied.The results show that in-situ calcium carbonate promotes the uniform distribution of HTCC/CMC matrix and significantly improves the mechanical properties of the film,but has little effect on the thermal stability,whiteness and wettability of the film.The strong electrostatic,hydrogen bonding and flexible interaction between CMC and in-situ crystallized calcium carbonate particles is the key to improve the mechanical properties of HTCC/CMC/calcium carbonate films.This work is to highlight the preparation of biodegradable biopolymer films and their potential applications in food and drug packaging.