Research On The Principle Of Gypsum Calcination Based On "phase Structure"

Gypsum is a kind of sulfate mineral,which is commonly used in traditional Chinese medicine.The clinical commonly used decoction pieces of gypsum are raw gypsum(Gypsum fibrosum)and calcined gypsum(Gypsum ustum).Raw gypsum is sweet,pungent and cold.It can clear heat and drain fire,eliminate irritability and allay thirst.It is mainly used for external-contraction febrile disease,high fever,vexation and thirst etc;Calcined gypsum is sweet,acrid,rough and cold,with functions of absorbing dampness,engendering flesh,closing sore and stanch bleeding.It is used for external use in the treatment of ulcerating sore,traumatic bleeding,etc.Under different calcining temperatures,gypsum can produce three stable structural variants,namely bassanite,soluble anhydrite and insoluble anhydrite.The spatial structures of gypsum's calcinates with different phase structures also show great variability,and different spatial structures can affect the physicochemical characteristics and clinical efficacy of gypsum's calcinates.In this study,raw gypsum and three gypsum's calcined products with different phase structure as the research objects,and the phase structure,physicochemical characteristics,and pharmacodynamic activity are thoroughly investigated to determine the optimal phase structure,which can be applied to optimize the processing,improve the quality,and ensure the clinical efficacy.ObjectiveBy comparing the physicochemical properties and scald repair effects of raw gypsum and gypsum's calcined products with different phase structures,to investigate the phase structure,physicochemical characteristics,and pharmacodynamic activity,lay the foundation for determining the optimal phase structure of calcined gypsum,improve the quality of calcined gypsum and ensure clinical efficacy,and also provide the basis for clarifying the processing principle of "Not Processed and Processed Chinese Medicine used in Different Situation" of gypsum.Methods(1)Preparation of raw gypsum and gypsum's calcined products with different phase structuresThe thermal decomposition process of gypsum was simulated by thermogravimetry,and the DTG curves of each thermal decomposition reaction stage were obtained by Gaussian fitting method.The activation energies of gypsum from six producing areas were calculated by CoatsRedfern method.Three calcining temperatures of 150?,350? and 750? were selected respectively,and the calcining time was set as 1.5 h.Three gypsum's calcined products with different phase structures were obtained.Their phase structures were characterized by fourier transform infrared spectrometry and X-ray diffraction.(2)Physicochemical properties of raw gypsum and gypsum's calcined products with different phase structuresScanning electron microscope,spectrophotometer,physical property analyzer,surface area porosity analyzer and low field nuclear magnetic resonance analyzer were used to investigate the micro characteristics,color and texture differences,specific surface area,pore size and hydration ability of raw gypsum and gypsum's calcined products with three different phase structures.(3)Study on the pharmacological mechanism of scald wound repair effect of raw gypsum and gypsum's calcined products with different phase structuresMacrophage inflammation model induced by LPS was used to investigate the antiinflammatory activity of raw gypsum and gypsum's calcined products with different phase structures.The inhibition effect of raw gypsum and gypsum's calcined products with different phase structures on Escherichia coli was investigated by dilution coating plate method.The damage degree of raw gypsum and gypsum's calcined products with different phase structures on state and surface structure of Escherichia coli was observed by scanning electron microscope,and antibacterial effect of raw gypsum and gypsum's calcined products with different phase structure was analyzed.A mouse model of skin scald was established.The healing effect of raw gypsum and gypsum's calcined products with different phase structures on skin scald was investigated by using histopathological studies and immunohistochemistry.Results(1)Preparation of raw gypsum and gypsum's calcined products with different phase structuresWhen the heating rate is 10?/min,the temperature range of the first dehydration process is 70-220?,and the range of activation energy E1 is 78.98-96.48 kJ/mol;the temperature range of the second dehydration process is 145-190?,and the range of activation energy E2 is 312.05-457.95 kJ/mol.The sequence of EI was Shanxi>Anhui>Hubei>Henan>Shandong>Hebei,and the sequence of E2 was Shanxi>Anhui>Henan>Hubei>Hebei>Shandong.The gypsum's calcined products are CG150,CG350 and CG750,respectively.The main phase structure of RG is gypsum,the main phase structure of CG150 is bassanite,the main phase structure of CG350 is soluble anhydrite,and the main phase structure of CG750 is insoluble anhydrite.(2)Physical properties of raw gypsum and gypsum's calcined products with different phase structuresThe results of scanning electron microscope show that RG is laminated in plate shape with compact structure and smooth surface,without cracks;Crack structure begins to appear on the surface of CGI 50;Fracture occurs on CG350 and the crystal structure becomes loose.The surface of CG750 has cracks,the structure is compact and the section is neat.RG structure is dense and hard,CG150 and CG750 have some cracks,but the crispness is low,CG350 is the crispiest.The results of colorimeter show that CG150,CG350 and CG750 are whiter than that of RG.The surface of CG350 and CG750 are redder.The surface of RG and CG150 samples are green,but the surface color of RG is greener than that of CGI 50.The surface of CG150,CG350 and CG750 are yellow,while the surface of RG is blue.The order of yellow degree is CG350>CG750>CG150.The results of physical property analyzer show that the hardness of RG is much higher than that of CG150,CG350 and CG750,the lowest hardness is CG750,and the higher hardness is CG150 and CG350.As can be seen from the results of the elasticity,adhesion and chewiness of sample powder,the elasticity,adhesion and chewiness of CG350 is the largest,while that of CG750 is the smallest.The results of specific surface area and pore size show that the order of specific surface area and pore volume from large to small is CG350>CG150>CG750>RG,and the order of pore diameter from large to small is RG>CG750>CG150>CG350.The surface area and pore volume of CG350 are the largest,but the pore diameter is the smallest,which indicates that there are many micropores in the CG350 sample.The results of low field nuclear magnetic resonance show that the order of hydration of raw gypsum and gypsum's calcined products with different phase structures is CG150>CG350>CG750?RG.(3)Study on the pharmacological mechanism of scald wound repair effect of raw gypsum and gypsum's different phase structure calcined productsThe in vitro anti-inflammatory activities of raw gypsum and gypsum's calcined products with different phase structures are as follows:the anti-inflammatory effects of CG150 and CG350 are stronger than those of RG and CG750,and there is no significant difference between CG150 and CG350.The in vitro antibacterial activities of raw gypsum and gypsum's calcined products with different phase structures are as follows:CG150,CG350 and CG750 all have certain antibacterial activities,but RG has no obvious antibacterial activity.The antibacterial activity of CG150 and CG750 is weaker than that of CG350.CG350 causes serious damage to the cell wall and cell membrane of Escherichia coli,and causes serious shrinkage of Escherichia coli,CG150 and CG750 causes slight damage to the surface of Escherichia coli,which indicates that the bacteriostatic effect of CG350 is the best.The skin healing effects of raw gypsum and gypsum's calcined products with different phase structures are as follows:CG750 and CG350 have obvious skin scald healing effect,while RG and CG150 have no obvious skin scald healing effect.CG750 and CG350 can inhibit inflammatory response,promote the regeneration of fibrous tissue,granulation tissue and hair follicle tissue,down-regulate the expression of IL-1? and up-regulate the expression of TGF.But,compared to CG750,the healing effect of CG350 is better.Therefore,among the samples,the healing effect of CG350 on scalded skin tissues in mice is best.ConclusionWhen the gypsum is calcined at different temperatures,the crystal water is lost,and the phase structure is also changing,resulting in bassanite,soluble anhydrite and insoluble anhydrite.The main phase structure of CG350 sample is soluble anhydrite,its surface structure is loose,its color is in line with characteristics of calcined gypsum,its texture is more crisp,its surface area and pore volume are larger,it has a certain hydration effect,its anti-inflammatory effect in vitro,antibacterial effect in vitro and skin scald tissue healing effect are better,which indicates that soluble anhydrite is the best phase structure of calcined gypsum.Under the condition of high temperature calcination,the gypsum lost the change of biological phase structure,and the suitable phase structure is the material basis for the gypsum to play the role of dampness and sore.When the gypsum is calcined at different temperatures,the crystal water is lost,and the phase structure is also changing,resulting in hemihydrate gypsum,soluble anhydrite and insoluble anhydrite.The main phase structure of CG350 sample is soluble anhydrite,its surface structure is loose,its color is in line with the traditional characteristics of calcined gypsum,its texture is more crisp,its surface area and pore volume are larger,it has a certain hydration effect,its anti-inflammatory effect in vitro,antibacterial effect in vitro and skin scald tissue healing effect are better,which indicates that soluble anhydrite is the best phase structure of calcined gypsum.Under the condition of high temperature calcination,the gypsum loses crystalline water completely and the phase structure changes.The suitable phase structure is the material basis for calcined gypsum to play the role of absorbing dampness and closing sore.From the point of view of repairing scald,it shows that the pharmacodynamic effect of gypsum is obviously different from that of calcined gypsum,clarifying the processing principle of "Not Processed and Processed Chinese Medicine used in Different Situation" of gypsum.