Investigation Of The Loading Abilities Of Drugs On Substrate Fibers In Supercritical CO₂ Fluid And Their Release Behaviors In Solvent

Supercritical fluid drug loading technology refers to the use of supercritical CO₂ fluid to dissolve or disperse the drugs,loading them into the polymer substrate,and thereby acting on the human body through releasing.This technology has attracted much attention in the pharmaceutical field and has relevant products available.In the field of textile,supercritical CO₂ fluid is mainly used for fiber dyeing currently.If drug loading technology with supercritical CO₂ fluid can be referenced,functional textiles with slow-release effects can form as functional substances are loaded into textile fibers through supercritical CO₂ fluid.At the same time,the application of supercritical CO₂ fluid in the textile field can also be greatly improved.In this paper,supercritical CO₂ fluid was used as the medium,viscose filament fabric and diacetate fiber were used as polymer substrate.Different types of drugs were selected,and the drug loading ability on fiber in supercritical CO₂ fluid and their release behaviors in solvent are explored.This research is mainly divided into three parts.Firstly,it touches upon the effects of drug solubility in supercritical CO₂ fluid,drug loading ability on fibers,and release behavior of drugs from fibers in release media caused by the changes in the polar groups,molecular weight,and spatial structure of the drugs.Secondly,it is concerned that loading ability of skin care drugs on viscose fiber in supercritical CO₂ fluid and their release behavior in solvent.And the loading ability,as well as the release behavior of nicotinamide and resveratrol,two skin care drugs,were compared.In the last part,the study of loading ability of skin care drugs on diacetate fiber in supercritical CO₂ fluid and their release behavior in solvent was introduced and the loading ability,as well as the release behavior of nicotinamide and resveratrol,were compared.In addition,the release behavior of the same drug from different substrate fiber was compared as well.The details are as follows.?1?According to the structure of cosmetic raw materials,nine drugs with different substituents,different molecular weights,and different spatial structures were selected,namely p-hydroxybenzoic acid?PHBA?,p-aminobenzoic acid?PABA?,methyl p-hydroxybenzoate?MPDB?,methyl p-aminobenzoate?MPAB?,ethyl p-aminobenzoate?EPAB?,n-butyl p-aminobenzoate?BPAB?,o-methoxy benzoic acid?2-MBA?,m-methoxy benzoic acid?3-MBA?,and p-methoxy benzoic acid?4-MBA?.Their solubility in supercritical CO₂ fluid,drug loading ability on the viscose substrate as well as their release behavior were explored,and ethanol was regarded as release medium.The achieved results show that the hydrophobicity of substituents can significantly improve the solubility of drugs in supercritical CO₂ fluid.What is more,concerning isomeric drugs with polar groups,as the substituents vary from ortho-position to para-position,the solubility of the drugs in supercritical CO₂ fluid gradually decreases.As far as the overall molecular structure of drug is concerned,the more hydrophobic it is,the better its solubility in supercritical CO₂ fluid is.The drug loading ability on the viscose fiber mainly depends on the solubility of the drug in the fluid.The greater the solubility is,the stronger the drug loading ability becomes.Meanwhile,if the drug shares a better affinity with the fiber,the drug loading ability on the fiber can be further improved.The absolute release amount and release rate of the drug from viscose substrate tend to rise with the increase of the drug loading ability on the fiber.However,the cumulative release behavior is mainly related to molecular polarity.The stronger the molecule polarity is,the slower the release rate from the viscose fiber and the smaller the cumulative release percentage becomes.?2?The skin care drugs,including nicotinamide and resveratrol,were selected as model drugs,with the viscose filament fabric as a polymer carrier,to explore the loading ability of skin care drugs on the viscose substrate in supercritical CO₂ fluid and their release behavior,and ethanol was regarded as release medium.To begin with,the effects of supercritical CO₂ fluid on the structure and properties of viscose fiber were investigated,on the basis of which,the effects of supercritical CO₂ fluid conditions on the loading ability of nicotinamide on viscose fiber were explored and the release behavior of nicotinamide-loaded viscose fiber was obtained.Subsequently,the effects of supercritical CO₂ fluid on the structure and properties of the skin care drug,nicotinamide,were studied,whose solubility in the fluid,the drug loading ability on viscose fibers,as well as the release behavior,were compared with resveratrol,another model drug mentioned above.Finally,the structure and properties of viscose fiber loaded with drugs were analyzed.The achieved results show that the surface morphology,chemical structure,aggregated structure,and thermal degradation properties of the viscose fiber does not change significantly after supercritical CO₂ fluid treatment.Only when the processing conditions are severe when the temperature reaches 120?;or the pressure increases to 20 MPa;or the time is prolonged to 120minutes,the intensity of the infrared absorption peak of a hydroxyl group and C-O-C group of viscose fiber decrease slightly.After reaching the equilibrium time of 60 minutes,the loading ability of nicotinamide which is loaded into the viscose fiber by supercritical CO₂ fluid does not increase.Generally the drug loading ability increases first and then decreases with the rise of fluid temperature,while increases with the rise of fluid pressure,and decreases first and then increases with the content of the entrainer used.The absolute release behavior of nicotinamide-loaded viscose fiber is closely related to the loading ability of nicotinamide in viscose fibers.The larger the drug loading ability is,the larger the absolute release amount is,and correspondingly,the faster the absolute release rate becomes.Nevertheless,the cumulative release percentage and cumulative release rate of nicotinamide-loaded viscose fiber increase with the rise of fluid temperature,but decrease with the rise of fluid pressure.The structure and properties of nicotinamide treated by supercritical CO₂ fluid does not change,while its stability to some extent improves.The solubility of nicotinamide in supercritical CO₂ fluid is significantly higher than that of resveratrol.Similarly,the loading ability of nicotinamide in viscose fibers is also higher than that of resveratrol.But absolute release behavior is still positively related to the loading ability of the two drugs in the fiber.The greater the drug loading ability is,the greater the absolute release amount and the greater the absolute release rate becomes.The cumulative release percentage and corresponding release rate of nicotinamide from viscose fiber are higher than that of resveratrol from viscose fiber.After loaded into the viscose fiber by supercritical CO₂ fluid,both nicotinamide and resveratrol which were dispersed on the surface of the viscose fiber were in a granular form.At the same time the two drugs were loaded into viscose fiber,which affects the microstructure of the viscose fiber.It increased the hydrogen-bond interaction of the macromolecular chain of the viscose fiber,what is more,resulting in variation in aggregated structure,along with a decline in crystallinity and heat resistance.However,its tensile fracture property is not affected.?3?The skin care drugs,including resveratrol and nicotinamide,were selected as model drugs,with the diacetate fiber as a polymer carrier,to explore the loading ability of skin care drugs on the diacetate fiber in supercritical CO₂ fluid and their release behavior,and ethanol was regarded as release medium.To begin with,the effects of supercritical CO₂ fluid on the structure and properties of diacetate fiber were investigated,on the basis of which,the effects of supercritical CO₂ fluid conditions on the loading ability of resveratrol on diacetate fiber were explored and the release behavior of resveratrol-loaded diacetate fiber was obtained.Subsequently,the effects of supercritical CO₂ fluid on the structure and properties of the skin care drug,resveratrol,were studied,the drug loading ability in diacetate fiber,as well as the release behavior,were compared with nicotinamide,another model drug mentioned above.Meanwhile,the release behavior of the same drug from viscose fiber and diacetate fiber were compared.Finally,the structure and properties of drug-loaded diacetate fiber were analyzed.The achieved results show that when supercritical CO₂ fluid treatment condition is relatively low,the structure and properties of diacetate fiber are not significantly affected.However,when the temperature of the fluid reaches120?;or the pressure rises to 20 MPa;or the time is extended to 120 minutes,some hydrogen bonds in the molecular chain of diacetate fiber are broken,which leads to the decline of the crystallinity.In addition,the thermal properties of the fiber are reduced.With the extension of the treatment time in supercritical CO₂ fluid,the loading ability of resveratrol on diacetate fiber has been increasing.But it decreases first with the rise of temperature and then increases,and keeps increasing with the rise of pressure of the fluid.The absolute release behavior of resveratrol from diacetate fiber is still closely related to its drug loading ability on diacetate fiber.The larger the drug loading ability is,the larger the absolute release amount is,and correspondingly,the faster the absolute release rate becomes.But the cumulative release percentage of resveratrol-loaded diacetate fiber in the release medium under the conditions of higher temperature and higher pressure of supercritical CO₂ fluid is lower,and the release rate becomes slower correspondingly.After treated by supercritical CO₂ fluid,the structure and properties of resveratrol do not change,but its stability improves to some extent.The loading ability of nicotinamide on diacetate fiber is also higher than that of resveratrol,and the absolute release behavior is still positively related to the loading ability of two drugs on diacetate fiber.The larger the drug loading ability is,the greater the absolute release amount for the drug from the diacetate fiber,and the absolute release rate becomes.However,comparing with nicotinamide the cumulative release percentage of resveratrol from diacetate fiber is lower.To the release behavior of the same drug form viscose fiber,diacetate fiber a slower release rate was obtained for nicotinamide from diacetate fiber,however,as well for resveratrol from viscose fiber.When the release reached an equilibrium resveratrol about 45%still kept in viscose substrate.At the same time,the washing resistance of the diacetate fiber loaded with resveratrol is significantly better than that of the diacetate fiber loaded with nicotinamide.After loaded into the diacetate fiber by supercritical CO₂ fluid,both nicotinamide and resveratrol which were dispersed on the surface of the diacetate fiber were in a granular form.Which affects the microstructure of the diacetate fiber.Some hydrogen bonds in the molecular chain of diacetate fiber are destroyed,leading to the transition of the macromolecular chain,from an ordered structure to a disordered one,and the decline of in crystallinity and thermal degradation.In addition,the tensile breaking strength of diacetate fiber decreases to some degree.Compared to nicotinamide the influences of resveratrol on the structure and properties of diacetate fiber are more significant.Finally,through the comparison of the applicability of viscose fiber and diacetate fiber as skin care fiber based on supercritical CO₂ fluid,it is found that supercritical CO₂ fluid makes a little effect on the aggregated structure of viscose fiber.However,when the fluid treatment is in severe conditions,aggregated structure and thermal properties of diacetate fiber are influenced.The loading ability of the drugs on the two fiber substrate mainly depends on the solubility of the drugs in supercritical CO₂ fluid.The release rate of the drug with stronger polarity from the viscose fiber tends to be slow.Due to the plasticization of the fluid to the diacetate fiber,it is easier for drugs to enter the interior of the diacetate fiber along with the supercritical CO₂ fluid,which can facilitate the drugs to release from the diacetate fiber at a slower rate.Compared with viscose fiber,the structure and properties of the diacetate fiber are more susceptible after drugs are loaded.In this paper,the loading ability of drugs on fiber substrate in supercritical CO₂ fluid and their release behavior in solvent were explored,which include drugs with different structures,under different supercritical CO₂ fluid treatment conditions.The influences of supercritical CO₂fluid on the structure and properties of fiber were also investigated.In addition,the stability of the drugs in supercritical CO₂ fluid and the changes in fiber structure and properties after drugs are loaded were explored.The research shows that it has been found that supercritical CO₂ fluid is of great value in the field of skin care fiber preparation.