Preparation And Properties Of Antibacterial Hydrogels With Drug Sustained-release Function

Drug sustained-release systems have been a hot research topic in the medical field in recent years.Compared with traditional drug delivery methods,the drug is combined with the drug in the form of physical or chemical adsorption to make corresponding dosage forms and enters the human body through diffusion and penetration,so that drug molecules can be released slowly in the human body at an appropriate concentration and at a stable and controllable rate,so as to give full play to its efficacy and effectively treat diseases.Drug sustained release system mainly consists of two parts:carrier material and drug molecule,and hydrogel is one of the main carrier materials in drug sustained release system,which is a water-soluble three-dimensional network composed of polymers,proteins,small molecules or colloids that can encapsulate and protect the drug,and is non-toxic to the human body,with good biocompatibility and biodegradability.Based on the current status,two hydrogels synthesized by using the Schiff base reaction were prepared in this paper.Schiff base compounds have good pharmacological activity and strong coordination ability,so the hydrogels prepared by using Schiff base reaction are very suitable as the medium material for drug slow release system.Two studies based on the preparation and sustained release properties of two new hydrogel composites for drug sustained release applications were carried out as follows:（1）Novel TiO₂-NPs/CNTs photocatalytic chitosan hydrogel drug delivery system to promote antibacterial properties and slow release of drugsThis chapter intends to design a novel composite hydrogel to be used as a carrier for drug sustained release system.The TiO₂-NPs/CNTs composite powder was firstly prepared by homogeneously coating titanium dioxide（TiO₂-NPs）on multi-walled carbon nanotubes（CNTs）by the sol-gel method,and then TiO₂-NPs/CNTs were doped into the preformed hydrogel using natural extract genipin（GP）as a cross-linking agent and carboxymethyl chitosan（CMCS）as a hydrogel matrix.The TiO₂-NPs/CNTs composite photocatalytic hydrogels with three-dimensional network structure were prepared.The samples were characterized by scanning electron microscopy（SEM）,infrared spectroscopy（FT-IR）,and ultraviolet-visible diffuse reflectance spectroscopy（UV-Vis）to analyze the microscopic morphology of the samples.The samples showed a continuous three-dimensional mesh structure with a large number of uniform pore channels.The sample exhibited strong photocatalytic activity in the visible region.The hydrogel exhibited good synergistic antibacterial properties under visible light with low toxicity.The delayed drug release performance of the hydrogel was also investigated using a drug model bovine serum protein（BSA）,which proved that it has good drug release control ability and can be used for short-term controlled release of positively charged common drugs with great potential for biomedical applications.（2）Preparation of aldehyde-based hyaluronic acid/sulfonated chitosan heparin-like structured hydrogels and their application in controlled drug release materialsIn this section,a chitosan hydrogel with heparin-like structure and high negative charge density is developed.Sulfonated chitosan（SCS）was prepared by indirectly introducing sulfonic acid groups onto chitosan（CS）by reacting the active molecule1,3-propanesulfonate（PS）bearing sulfonic acid groups with hydroxyl and amino groups.Afterwards,the C=C cleavage of the cis-diol group in the hyaluronic acid（HA）molecular chain generates active aldehyde groups to prepare aldehyde-based hyaluronic acid（OHA）,and finally OHA/SCS drug-controlled hydrogel is prepared by cross-linking reaction with amino groups through Schiff base bonds.The morphology and structure of the samples were characterized by nuclear magnetic resonance hydrogen spectroscopy（¹HNMR）,infrared spectroscopy（FT-IR）and scanning electron microscopy（SEM）.OHA/SCS hydrogels have a porous structure with pore sizes ranging from 100 to 200μm.With the increase in OHA dosage,the hydrophobic property of the gel system increases,which affects the hydrophilicity and decreases the swelling ratio.In vitro experiments with BSA as the model drug confirmed that the OHA/SCS hydrogels possess good drug slow release performance with a cumulative drug release rate of 74%-88%and a release time of 9 days,indicating that the OHA/SCS hydrogels have promising applications in the field of drug controlled release.