| Objective: The purpose of this paper is to combine polyamide-amine dendrimer(PAMAM)with ionic in situ gel after functional modification and physical drug loading,which can overcome the limitation of nasal absorption.Thus,a PAMAM nanocomposite-in situ gel delivery system based on "nasal-brain" transport is constructed.We will study the characterization of the drug delivery system,drug release in vitro,cell evaluation and the feasibility of "nasal-brain" transport,so as to provide a new and effective strategy for the application of PAMAM as a nano-drug carrier in drug brain-targeted delivery.Methods: PAMAM was modified by PEG,acetylation and fluorescence based on chemical bonding,the model drug paeonol(PAE)was encapsulated in physical cavities,PAE/m PEG-PAMAM G5.NHAc drug loading nanocomposite and m PEG-PAMAM G5.NH2-FITC fluorescent tracer nanocomposite were constructed.IR and1H-NMR were used to track and verify the synthesis,particle size distribution,surface potential and electron microscope were used to observe and characterize the nano-characteristics of the nanocomposite,HPLC method was used to determine the entrapment efficiency and drug loading rate of PAE,and response surface method was used to optimize the preparation composition of in situ gel.The in situ gel system was characterized by critical ion concentration,viscosity,gel strength,rheology and so on.The drug release characteristics in vitro were investigated by dialysis bag method,the cytotoxicity of PAMAM nanocomposites was detected by MTT assay,and the cell uptake of PAMAM nanocomposites was investigated by confocal analysis.The feasibility of "nasal-brain" transport of PAMAM nanocomposite-in situ gel delivery system was investigated based on in vivo imaging technique.Result:The particle size of PAE/m PEG-PAMAM G5.NHAc and m PEG-PAMAMG5.NH2-FITC were 72.41 ± 11.58 nm and 96.51 ± 7.77 nm,and the zeta potential of PAE/m PEG-PAMAM G5.NHAc and m PEG-PAMAM G5.NH2-FITC were + 0.57 ± 0.11 mv and + 9.60 ± 0.41 mv,respectively.The EE% and DL% of PAE in PAE/m PEG-PAMAM G5.NHAc were 53.77% and 13.92%,respectively.The viscosity of solution and gel state were 112 ± 3.2 m Pa and 1403 ± 38.5 m Pa,respectively.The in vitro goat mucoadhesive strength of the gel was 4763.36 ± 85.39 dyne/cm2.Rheological analysis proved that the in situ gel system was a non-Newtonian pseudo-plastic fluid with shear thinning,thixotropy and yield stress.The optimal model of PAE released from PAE/m PEG-PAMAM G5.NHAc and PAE/m PEG-PAMAM G5.NHAc/DGG were the Higuchi equation and the Korsmeyer-Peppas equation,respectively.The cytotoxicity of the nanocomposites showed a concentration-dependence,and the cell viabilities of PAE/m PEG-PAMAM G5.NHAc were both higher than 95% between 0.0001 μM and 10μM.m PEG-PAMAM G5.NH2-FITC was efficiently taken up by cells and exhibited strong fluorescence in the cytoplasm and nucleus.A small amount of accumulation was observed in the nanocomposite solution group only at 2 h.Significant accumulation of nanocomposites was observed in the brain after administration of the in situ gel group,and maximum accumulation was reached at 12 h.Conclusion: The combination of PAMAM nanocomposite with in situ gel can significantly improve the nasal absorption level and thus improve the transport efficiency of "nasal-brain".PAMAM nanocomposite-in situ gel delivery system based on "nasal-brain" transport is a potential strategy to realize the application of PAMAM as nano-drug carrier in drug brain-targeted delivery. |
PDF Full Text Request