Controlled Drugs Release Of AC And DC Stimulated Based On Polypvrrole

The controlled drug release system is a system capable of intermittent drug release under exogenous or endogenous stimuli.This system can effectively control the time,rate and amount of drug release,reducing the number of times the drug is taken,and maintain the drug for a long time concentration to achieve better treatment effect.Polypyrrole has a wide range of biological fields due to its unique substitution/desubstitution properties,good electrical conductivity,and biocompatibility.This thesis focuses on the following aspects of research on the controlled release of drug release systems using polypyrrole as a carrier under electrical stimulation:(1)The polypyrrole-adenosine triphosphate(PPy-ATP)films with different morphologies on an array chip substrate was prepared by the galvanostatic method using a mixed solution of pyrrole(Py)and adenosine triphosphate(ATP).The morphology characterization,element analysis and structure analysis of the obtained PPy-ATP films were carried out by scanning electron microscopy(SEM),energy dispersion spectroscopy(EDS),and Fourier infrared spectroscopy(FTIR).And cyclic voltammetry and electrochemical impedance method were used to test the electrical performance of the prepared drug chip.The following conclusions are obtained:ATP and PPy form a complex PPy-ATP film through a certain interface interaction(doping,adsorption,etc.).As the current density increases,the density of the PPy-ATP film formed by polymerization decreases,the surface roughness increases,and the degree of doping of ATP increases proportionally,resulting in hindered electron transport in the composite material,resulting in the redox current of the PPy-ATP film gradually The conductivity decreases gradually,which reduces the impedance value of the drug chip by about 1.5 to 3 orders of magnitude.(2)To study the effect and mechanism of DC potential stimulation on drug release.The experimental results showed that:When the current density is 0.5 and1.0 m A/cm~2 for 5 hours,controlled release of the drug can be achieved with different DC potentials,and the average cumulative release rate is 80%.With the increase of the DC potential amplitude,the faster the release rate of ATP,the greater the cumulative release rate,and the release trend remains similar.As the amplitude of DC potential increases,the drug release rate and the cumulative release rate are faster,and the release time to saturation is shorter.Analysis of the release mechanism of DC electrical stimulation:during the process of DC potential,the PPy-ATP film becomes denser from the conductor to the insulator,which gradually causes the drug ions to gradually change from electromigration release to diffusion release,which is slower.The release trend finally reached equilibrium.(3)An experimental study on the effect and mechanism of alternating current signals on drug release.Experimental results show that when the frequency is 2Hz,the total cumulative release rate is similar at±0.8 and±0.5 V,but the cumulative release rate of the former is faster than that of the latter.The cumulative release rate and release rate at±0.3 V are all lower than those release results at±0.5 V.When the potential is±0.8 V,as the frequency increases,the drug release rate and cumulative release rate show a gradual downward trend,and it takes longer to reach saturation release.The release mechanism of AC electric stimulation is that the positive and negative changing potentials make the PPy-ATP film alternately in the oxidation-reduction state,so that the anionic drug is released during the reduction process,cations and water molecules are absorbed,resulting in volume expansion and destroying the reversibility of the film.During the oxidation process,the anions(partially ionic drugs)in the solution are re-doped,while the cations and water molecules in the film are expelled,resulting in volume shrinkage.With the in and out of ions and water molecules,the volume of the film is changed,and the rate and content of drug diffusion from the film into the release medium are changed.