Preparation Of Surface Molecularly Imprinted Polydopamine Nanospheres And Its Application In Drug Delivery

Dopamine contained catechol functional groups and amino functional groups was used as simulants of mussel adhesion proteins.This work found that dopamine can not only form polydopamine coating on the surface of matrix material by oxidative selfpolymerization,but also form polydopamine nanospheres(PDA NPs)in ethanol / ammonia mixture.Obtaining the stable and controllable PDA NPs,the effects of preparation factors such as pH value,reaction time and dopamine concentration on the particle size and morphology of PDA NPs were discussed.At the same time,the formation process,mechanism and basic properties of PDA NPs were studied.Based on the above studies,we try to carry out the molecular imprinting of the model proteins on the surface of PDA NPs with uniform size,achieving sustained-release release of the model protein molecules.In addition,the influence of the thickness of polydopamine coating on the drug loading was studied and the drug carrier was compared with the previously studied polymer particle drug delivery system,which provided a reference for the application of poly dopamine microspheres in the field of biomedical applications.The main work of this paper is the following two parts.Ⅰ PDA NPsPDA NPs could be prepared by oxidative self-polymerization of dopamine in the oxygen-containing alkaline environment.In this experiment,the effects of reaction factors such as pH value,reaction time and dopamine concentration on the preparation of PDA NPs were investigated.The PDA NPs were observed by scanning electron microscopy(SEM),transmission electron microscopy(TEM)and DLS.The results confirmed that the size controlled and well dispersed PDA NPs were prepared.Ultraviolet–visible spectroscopy was used to research the reactivity of dopamine.PDA coating exhibit good hydrophilicity and secondary reactivity.PDA NPs exhibited no cytotoxicity to NIH-3T3 at concentration of below 100 mg/mL.In addition,the results of blood compatibility evaluation indicated that smaller PDA NPs have better blood compatibility.The experimental results provide a data support for the preparation of size controlled and well dispersed PDA NPs and lay a foundation for the molecular imprinting experiments.Ⅱ Surface molecular imprinting productsIn this work,we report a novel method for imprinting protein on the surface of PDA NPs,choosing lysozyme(Lys)as the template and dopamine as the functional monomer.The size of PDA NPs adsorbed by template protein can grow again in the solution of flash dopamine by self-polymerization of dopamine.In this procedure,template protein molecules were embedded in PDA coating.The template protein imprinted sites are produced by removing the embedded protein molecules.The related products were characterized by physical and chemical methods.PDA NPs could be modified by Lys and dopamine.The thickness of the formed polydopamine coating increases with increasing flash dopamine concentration and reaction time.Surface molecular imprinting products could load more drugs and specifically recognize model drugs.The results of drug delivery showed that the surface molecular imprinted products had better sustained release properties.The above experiment provides a new idea for molecular imprinting of biomolecules such as protein.