| In recent years,chemical method develops rapidly,and combines with medicine,pharmacy,biology,physics and other fields frequently.The research on the simulation of biochemical reaction,the performance of medical materials,the metabolism of drugs in vivo,the influence of drugs on the metabolism process of life is booming.Candida albicans is a common bacteria in the oral cavity,is a conditional pathogen,but once the infection occurs,it is very difficult to cure,especially the correction period because of the difficulty of cleaning orthodontic appliances,so the probability of Candida albicans infection increase significantly.The influence of drug molecules on the normal metabolism of Candida albicans can be indicated by the change of heat generated in the metabolic process,the change of oxygen consumption in the metabolic process,the change of absorbance value,the change of absorption capacity of nutrients,etc.The influence of drugs on the growth and metabolism of Candida albicans and the inhibition effect of drugs on Candida albicans on the surface of the appliance can be investigated by simulating the living environment of Candida albicans and the growth state of microorganisms during orthodontic treatment in vitro.In this paper,the effects of drug molecules on the metabolism of Candida albicans from different perspectives and levels were studied by microcalorimetry and electrochemical analysis combined with other advanced methods and instruments.No matter complicate organism,simple cells and organelles,metabolic heat is produced in the process of life.However,conventional calorimetry technology is difficult to accurately monitor these subtle heat changes due to the large error and poor stability.In order to obtain the micro heat of chemical change between molecules,the micro heat of biochemical reaction in the organelle,and the macro heat of cell and microorganism growth and metabolism,micro heat technology was applied widely.It can collect heat at the level of nanowatt by using the biological thermal activity monitor.Until the 1980s,there were more and more scholars engaged in micro thermal research in China,and the technology developed vigorously.Microcalorimetry has the advantages of simulating environment,sample destructiveness,high efficiency,multi-channels,real-time continuous,fast and sensitive.Biothermal activity monitor can obtain a series of important dynamic and thermodynamic information of cells and colonies from stable growth to exponential growth,and then to decay.Electrochemical analysis is a developing analytical method,widely used in electrolysis,battery,semiconductor and so on.However,its application in biological system is still in a rapid developing,and its depth and scope are also expanding.The main advantages of electrochemical method in biomedical research are:sample processing is relatively simple,without labeling;most of the reaction process in the organism can be simulated by electrochemical reaction;sample destructiveness is relatively small,the test is efficient,and the sensitivity is high;the collected electrical signals can be converted into some important thermokinetic information,and so on.In this paper,the effects of chlorhexidine and other drugs on the growth and metabolism of Candida albicans were studied.The main contents of this paper are as follows:(1)This paper summarizes the characteristics of Candida albicans in the oral cavity,the current situation of the treatment of Candida albicans on the surface of orthodontic appliance,the development and application of microcalorimetry in the field of life science and pharmaceutical pharmacology,as well as the current situation of self-assembly methods and electrochemical analysis of gold electrode surface in common use combined with the work of this research group.(2)The inhibitory effects of chlorhexidine,curcumin,econazole and miconazole on Candida albicans in vitro were studied in detail by microcalorimetry.The thermodynamic and kinetic parameters of the growth and metabolism of Candida albicans under the action of drugs were obtained.The growth rate constant k,the exothermic peak Pm,the passage time tG and the inhibitory effect of each drug on Candida albicans were analyzed or calculated.The relationship between the growth rate constant and the concentration of the drug and the semi inhibitory concentration of the drug were obtained.Through multi-level comparison,it is concluded that the effect of four drugs on Candida albicans is different:chlorhexidine>miconazole>Econazole>curcumin.In addition,UV-Vis spectrophotometer was used to reveal the effect of the drug on Candida albicans from OD value,and the effect was basically the same as that of microcalorimetry.(3)The proliferation of Candida albicans on the surface of ceramic,self-locking metal and common metal appliance was observed by routine biomedical test.The results of colony count and light absorption showed that the number of Candida albicans was ceramic dental braces>self-locking metal dental braces>common metal dental braces,and the number of Candida albicans attached to ceramic appliance was more than 2 times of self-locking metal appliance,almost 10 times of common metal appliance.In order to obtain more information of chemical kinetics and thermodynamics,the microcalorimetric method was used to simulate the 37℃ oral environment.The in vitro inhibitory effects of chlorhexidine,curcumin,econazole and miconazole on Candida albicans on the surface of ceramic,self-locking metal and common metal appliance were systematically studied.The data analysis or calculation of the effects of each drug on Candida albicans were carried out.According to the growth rate constant k and the relationship between the growth rate constant and the drug concentration,it is concluded that the difference of the inhibition effect of the four drugs on Candida albicans is chlorhexidine>miconazole≥ Econazole>curcumin,and the inhibition effect of the drugs on the surface of the dental braces is:common metal dental braces>self-locking metal dental braces>ceramic dental braces.The results of absorbance experiment are basically consistent with microcalorimetry.(4)The interaction between Candida albicans and extracellular DNA was studied by electroanalysis.The gold electrode was assembled layer by layer,and Candida albicans was fixed on the surface of the electrode.In the redox system of iron ions,the thermodynamic information of adsorption of herring sperm DNA on the cell surface was investigated.The dynamic curve of adsorption of extracellular hsDNA by Candida albicans was obtained by cyclic voltammetry.The calculated equilibrium binding constant k was 5.867×106 L·mol-1.In addition,the influence of chlorhexidine,curcumin,Econazole and miconazole on the adsorption process was also studied.The results showed that chlorhexidine had a great influence on the outer membrane structure of Candida albicans.Its K value was 0.0431 L·mol-1,which was higher than 0.0296 L·mol-1 of econazole,0.0259 L·mol-1 of miconazole and 0.0094 L·mol-1 of curcumin.The results provide useful theoretical information for the adsorption and utilization of extracellular DNA by microorganisms. |
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