| Gold nanoparticles(Au NPs)are widely used in drug delivery,catalysis,energy storage,and microreactors due to their excellent stability,biocompatibility,nearinfrared response performance and unique surface plasmon resonance characteristics.However,how to hybridize gold nanoparticles and biological macromolecules to promote the research of multifunctional hybrid gold nanomaterials with new characteristics still requires the unremitting efforts of researchers in many fields.Gold nanoparticle microcapsule is a new type of microcapsule,in which gold nanoparticles are used as the structural unit.By combining the properties of gold nanoparticles with the functions of hybrid assemblies,the construction of hybrid nanoparticle assemblies embedded in the surfaces of various microcapsules or gold nanoparticles has attracted much attention.However,the successful construction of these microcapsules will depend on the precise control of the size,shape and surface chemistry of gold nanoparticles.In addition,microcapsules have some problems such as difficulty in rapid regulation of permeability,low mechanical strength,and poor biocompatibility,which limit their applications.These problems can be solved successfully by combining gold nanoparticles with microcapsules with precise and controllable morphology and properties.In this paper,quasi-spherical superstructures of gold nanoparticles and hybrid microcapsules of gold nanoparticles/biological macromolecules were constructed around the assembly design of gold nanoparticles and biomolecules,and the assembly morphology and function regulation of microcapsules were investigated in depth.The main contents are summarized as follows:Small sized gold nanoparticles(5 nm)were synthesized with sodium citrate and tannic acid as the hybrid ligands.Firstly,the synthesized gold nanoparticles can be induced by iron ions to assemble into quasi-spherical superstructures(about 50 nm),and the addition of copper ions to the gold nanoparticles can also induce them to assemble into similar superstructures(about 50 nm).The addition of iron ions to gold nanoparticles synthesized by sodium citrate and tannic acid alone could not form similar assemblies,but the combination of sodium citrate and tannic acid had a synergistic effect on the assembly of gold nanoparticles into quasi-spherical superstructures.The citric acid and tannic acid on the surface of gold nanoparticles tend to form phase separation in a smaller surface free energy,leading to local interaction between the metal and phenol to achieve spontaneous assembly.Secondly,the addition of ethylenediamine tetraacetic acid as a stronger iron chelating ligand allowed the reversible assembly and disassembly of gold nanoparticles at least 5 times.The assembly of gold nanoparticles was constructed by using ligands on the surface of gold nanoparticles to lay a solid foundation for further construction of functional gold nanoparticle assemblies.Then,by grafting temperature-sensitive poly(N-isopropylacrylamide)(PNIPAAm)and hydrophilic m PEG-SH on the surface of gold nanoparticles(15 nm),Pickering emulsion method was used to synthesize oilcoated gold nanoparticles with interfacial catalytic properties.PNIPAAm grafted on the surface of gold nanoparticles is also thermally sensitive.Gold nanoparticle microcapsules are composed of polymer monolayer grafted by gold nanoparticles and have a highly stable structure,which can be dispersed and stabilized in solution for more than 4 weeks.Under the near infrared(NIR)irradiation at 808 nm,the photothermal properties of gold nanoparticles in the film caused the microcapsules to show hydrophobicity due to the phase transition of PNIPAAm(LCST).The interfacial catalytic rate of alkaline phosphatase(ALP)loaded inside the microcapsule was increased by about 10 times under the near infrared irradiation of 808 nm than that of none-microcapsule.In order to further regulate the performance of gold nanoparticle microcapsules,gold nanorods grafted with the thermo-sensitive poly(N-isopropylacrylamide)(PNIPAAm)was further covalently grafted onto the surface of protein microcapsules,and a dynamically regulated microreactor with near-infrared responsiveness was constructed.The excellent photothermal conversion efficiency of the embedded gold nanorods and the thermal phase transition of the grafted PNIPAAm enable the proteinosomes to exhibit reversible contraction behavior triggered by near-infrared light,with the microcapsules contracting as fast as 1 minute and lasting for at least 15 cycles.By loading three cascade enzyme(glucan hydrolase,glucose oxidase and horseradish peroxidase)into the microcapsules as a microreactor,reversible regulation of enzyme cascade reactions can be opened and closed by near-infrared light irradiation at 808 nm.Based on the functional construction of the gold nanoparticle microcapsule reactor,L or D penicillamine(L/D-pen)was further extended on the graft surface of gold nanoparticle,and a chiral gold nanoparticle hybrid microcapsule was constructed by hybrid assembly of proteinosomes.Self-assembled chiral microcapsules not only serve as microreactors,but also provide a chiral environment for chiral recognition.When glucose oxidase and horseradish peroxidase were included in the microcapsules,and D-type glucose and ABTS were added as substrates,the reaction rate of D-type chiral microcapsules was significantly reduced.By optimizing the Lattice parameters of cubic Au cell and comparing the interaction force between D glucose with L or D penicillamine,it was calculated that the adsorption energy between D glucose and type D penicillamine(-0.095)was lower than that between D glucose and L penicillamine,which indicated the stronger interaction force for the former.Thus,through the chiral recognition on the membrane surface,the hybrid microcapsules were loaded with glucose oxidase to regulate the reaction rate of enantiomer selection of D-type glucose substrates. |
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