Functionalization and Application of Dopamine-Containing Self-Assemblies

Author:Wang Jie

Supervisor:yan de yue zhou yong feng


Degree Year:2016





As molecular self-assemblies have been widely applied in many fields,such as catalysis,drug delivery,sensors and self-healing materials,the functionalization of self-assemblies has attracted intensive interests.Thus,it is of great significance to develop a universal and simple method to prepare assemblies with diverse functionalities.In this dissertation,we present a facile method to prepare self-assemblies with diverse functionalities by introducing dopamine(DA)into them,and the so-formed DA-containing assemblies could be further readily surface functionalized with several functional moieties,such as proteins,DNA,metal nanoparticles,etc,just by mixing them together.The dissertation contains four parts,and the main contents and conclusions are shown as follows:1.Self-crosslinking and surface functionalization of dopamine-containing polymer vesicles.The hyperbranched multi-arm copolymer HSP was grafted with dopamine to prepare HSP-DA polymer,which can self-assemble into vesicles in water.The vesicles can be self-crosslinked by adjusting the solution pH to 8.0 to induce the polymerization of DA,and the structure of the crosslinked vesicles(CVs)was proved by DLS,TEM,SEM,and optical microscopy characterizations.The CVs show good stability and can stay stable at66.7%aqueous ethanol solution.Afterwards,the CVs can graft BSA,DNA and meso-2,3-dimercaptosuccinate sodium solution to obtain BSA-modified vesicles,DNA-modified vesicles and carboxyl-modified vesicles,respectively,by mixing the functional moieties with CVs together.Furthermore,the corresponding functionalization mechanism was proposed.2.Preparation of noble metal nanoparticles hybrid vesicles and their applications in the Surface Enhanced Raman Scattering(SERS)effect.The gold nanoparticles(AuNPs)or silver nanoparticles(AgNPs)hybrid vesicles were obtained through mixing CVs and AuNPs or AgNPs together.The formation of AuNPs hybrid vesicles(AuNPs@CVs)and AgNPs hybrid vesicles(AgNPs@CVs)were confirmed through TEM and UV-Vis spectroscopy measurements.The Raman spectra of hybrid vesicles showed a significant enhancement of the Raman signals of the components of the CVs,compared with the barely visible Raman signals from CVs.Thus,both AuNPs@CVs and AgNPs@CVs can be used for in-situ detection of the vesicle components through the strong SERS effect.Then,AuNPs@CVs and AgNPs@CVs were further used as SERS probes to detect Rhodamine 6G molecules in the aqueous solution with a concentration of 10-7 mol/L.The Raman signals of Rhodamine 6G were enhanced greatly,and the enhancement by AgNPs@CVs was greater than that by AuNPs@CVs.Thereupon,AgNPs@CVs were further applied in the trace detection of the analytes like malachite green,methyl orange and Sudan-1.3.Preparation and application of polydopamine(PDA)capsules.PDA capsules were prepared by self-polymerization and deposition of dopamines onto the surface of HSP-DA vesicles.The TEM,SEM and optical microscopy characterizations show the stable PDA capsules can be obtained when the mass ratio of HSP-DA/DA·HCl is 1:1.PDA capsules can reduce HAuCl4 to generate AuNPs,which were adsorbed on the surface of PDA capsules to form AuNPs coated capsules(Au@Capsule),according to the TEM,SEM and EDS characterizations.The Raman spectroscopy of Au@Capsule solution showed a significant SERS effect.In addition,PDA capsules were carbonized in a vacuum furnace at 350-700°C to generate carbon material,as proved by Raman spectroscopy and X-ray diffraction characterization.Carbon spheres were observed under the SEM and FE-TEM measurements,but no porous structure was obtained.4.Preparation and surface functionalization of dopamine micelles.Tween 60 molecule was grafted with dopamine to prepare TDA molecule,which can self-assemble into micelles in water.The TDA micelles can be self-crosslinked by adjusting the pH to 8.0 due to the polymerization of the grafted DA molecuels,and the as-prepared crosslinked PTDA micelles were proved by the DLS,TEM,and UV-Vis spectroscopy measurements.Then,DNA was mixed with PTDA crosslinked micelles to obtain DNA-modified micelles,based on the FTIR and UV-Vis spectra.Afterwards,AuNPs hybrid micelles(AuNPs@PTDA)were prepared through the in situ reduction of HAuCl4 by sodium citrate on the surface of PTDA crosslinked micelles.AuNPs@PTDA showed high catalytic activity when tested by the reduction of 4-nitrophenol with NaBH4in the presence of AuNPs@PTDA.In addition,Raman spectroscopy of AuNPs@PTDA solution showed a significant SERS effect,indicating the potential for in-situ detection of the micelle components.