Study On Preparation Process Of Salicylic Acid Microcapsules

Salicylic acid,a phenolic acid that is soluble in fat,possesses antibacterial and anti-inflammatory properties.It finds broad application in various fields such as daily chemicals,medicine,and food.Salicylic acid,due to its poor compatibility and irritation in direct contact with the skin,is difficult to be used as an effective component of daily chemical products.Water soluble microcapsules prepared by spray drying technology can solve the compatibility and irritation problems of salicylic acid used in daily chemical products.The present study investigated the preparation process of high-load microcapsules containing salicylic acid using spray drying technology.The following main achievements were obtained:(1)Salicylic acid microcapsules were prepared from acacia maltodextrin composite wall material by spray drying technology.Using anhydrous ethanol and isopropyl palmitate as dispersing solvent of salicylic acid,Optimization of the wall material concentration,core wall ratio,shear rate,inlet temperature,and feed rate was carried out under both single factor and orthogonal conditions.Under optimized process conditions,the drug carrying capacity and encapsulation rate of salicylic acid microcapsules prepared with ethanol dispersing agent were 29.7% and 24.5%,respectively.The drug loading capacity of the product prepared with isopropyl palmitate dispersant was 8.2%and the encapsulation rate was 70.1%.β-cyclodextrin was used to prepare microcapsules by inclusion salicylic acid.Firstly,the inclusion time,temperature and molar ratio of raw materials were optimized.The low temperature precipitation and spray drying processes were compared from two aspects of drug loading and encapsulation rate.The drug loading of salicylic acid was obviously increased.β-cyclodextrin-salicylic acid microcapsules with 23.2% drug loading and 85.2% encapsulation rate were obtained under optimized conditions.(2)Characterization of salicylic acid microcapsules was performed using electron microscopy,X-ray diffraction,infrared spectroscopy,and thermogravimetry.The microcapsules obtained by spray drying were regular hollow spheres,the surface of the salicylic acid microcapsules with acacia gum and maltodextrin as the wall material was smooth,the surface of theβ-cyclodextrin microcapsules with the wall material was irregular folds,and the β-cyclodextrin microcapsules prepared by precipitation at low temperature were regular diamond shaped blocks.The particle size distribution of the microcapsules obtained through spray drying was found to be narrow,with an average particle size ranging from 2-15 μm.Moreover,an increase in solution concentration was found to be proportional to an increase in particle size.The microencapsulation process also led to a reduction in the crystallinity of salicylic acid,which in turn enhanced its solubility.The analysis of surface functional groups can confirm that the formation of salicylic acid microcapsules belongs to physical encapsulation,the skeleton structure of the microcapsules is basically consistent with the wall material,besides the physical coating between β-cyclodextrin and salicylic acid,there is also a weak interaction of hydrogen bonds between molecules,β-cyclodextrin coated microcapsules in thermal stability and antioxidant performance showed excellent.(3)The antioxidant,bacteriostatic and slow-release properties of salicylic acid microcapsules were evaluated.The antioxidant activity of salicylic acid microcapsules did not decrease significantly compared with that of pure salicylic acid,and the antioxidant activity of β-cyclodextrin microcapsules was better than that of acacia maltodextrin composite wall materials.Salicylic acid microcapsules can inhibit Propionibacterium acne and staphylococcus aureus,and its bacteriostatic ability is better than that of commercial salicylic acid microcapsules.The sustained release experiment showed that the release rate of salicylic acid microcapsules was significantly slower than that of pure salicylic acid,and the release time could last about 7 h.(4)by spray drying technology with Arabic gum and maltodextrin composite wall to package of retinol,compared with the 9.6% retinol microcapsule drug loadings,parcel at a rate of 40.9%.The microcapsules exhibited a spherical structure under electron microscopy,with an average particle size of approximately 13 μm.Additionally,the thermal stability of the retinol microcapsules was observed to be higher compared to that of pure retinol.Therefore,spray drying method can be solved in the preparation of microcapsule of salicylic acid,the effect such as retinol ingredients used in cosmetic products key bottlenecks,and easy to enlarge industry,for the application of salicylic acid in cosmetic fields such as provides technical reference.