| The slow/controlled release drug delivery system is a dosage form that allows the drug to distribute the required amount of drug to the site of action at an appropriate speed,so that the drug can reach the ideal concentration.Slow/controlled release preparations according to the physical and chemical properties,the size of the dose,and the release rate required to select the appropriate slow/controlled release materials and preparation methods.The diverse natural biomass materials formed in nature provide a wide range of raw material sources and innovative ideas for the development of slow/controlled release materials.Shrimp and crab shell is a natural nanoporous material with chitin,protein and calcium carbonate as the main components.It has a capillary network structure that can meet the body fluid circulation and is an ideal raw material for slow-release carriers.Our group invented a new technology for the clean production of chitosan and carboxymethyl chitosan from shrimp and shell in patents CN104788584A and CN109966505A.It was discovered that calcium carbonate and its compounds prepared from shrimp shell raw materials have loading capacity and slow-release effect on organic pesticides.However,in the preliminary work,there is a lack of in-depth research on the pore characteristics and loading rules of the carriers,especially the lack of benchmarking research on inorganic salt slow-release preparations such as KCl.This paper is based on the preliminary research of our group,selecting crab shell to prepare 6 kinds of slow-release carriers.The structure was characterized by FT-IR,XRD,EA,SEM,and the product composition,specific surface area and porosity,Zeta potential were quantitatively analyzed.Using the solution adsorption method to prepare inorganic and organic drug slow-release preparations,the loading and release rules of the slow-release carrier were studied,and the preliminary efficacy evaluation of the slow-release preparations was carried out.The results show that compared with shrimp shell powder and carrier materials prepared therefrom,crab shell powder and carrier materials prepared therefrom have larger specific surface area,larger pore volume,and smaller pore size.Such materials with large pore volume and small pore diameter have the potential to be developed and applied as slow/controlled release carriers.It was found that the Zeta potential of the slow-release carrier under different ion concentration and pH can be used to determine the surface charge and drug loading mechanism of the slow-release carrier.The water absorption of the slow-release carrier under different pH can also be used to analyze the opening and closing behavior of the carrier pores.The quantity loading of KCl is 1.4%～47%,and the release time is 24～96 h.The C-CS/CaCO3 and C-CaCO3 have the best loading and release effects,which meets the dissolution requirements of the Chinese Pharmacopoeia for KCl slow-release tablets.The glyphosate isopropylamine salt slow-release preparations prepared from the C-CT/PRO has herbicidal control effects similar to that of glyphosate isopropylamine salt quick-acting pesticides,and has a long-term inhibitory effect.In this study,by directly using the natural nanoporous structure of the crab shell raw materials,the pore characteristics and loading rules of the slow-release carrier prepared therefrom were discovered,and a method for optimizing ion concentration and pH by Zeta potential was proposed.The results of this research are of great significance to the development of natural nanoporous carrier materials and a series of slow-release functional products. |
