Preparation Of Novel Nanohybrid Materials Using Surface Functionalized Nanoparticles

In this work,a series of surface functionalized nanopaticles were synthesized, and based on which novel nanohybrid materials were designed and fabricated.The structural,electronic and spectroscopic properties of the obtained nanohybrid materials were characterized to explore their potential applications in the fields like optoelectronics and biology.The main results are as below:1.CdSe quantum dots(QDs) modified porous TiO₂ films were prepared and their photo energy conversion efficiencies were studied.CdSe QDs with different sizes were prepared by pyrolytic method.Meanwhile,anatase form of TiO₂ thin films were prepared by anodic oxidation of titanium plates.By using bifunctional linkers modifiers,CdSe quantum dots(QDs) were assembled onto mesoscopic anatase TiO₂ films to give CdSe QDs sensitized TiO₂ thin films.The photoactivities of the new nanostructures under visible light illumination were investigated,and the possible electron transfer mechanism between CdSe QDs and the TiO₂ film was discussed.2.Novel nanohybrids containing carbon nanotubes(CNTs) and CdSe quantum dots (QDs) were prepared through electrostatic self-assembly method.The CdSe QDs were capped by three mercaptocarboxylic acids,including thioglycolic acid(TGA), dihydrolipoic acid(DHLA) and mercaptoundecanoic acid(MUA),which provide shell thickness of 5.2,10.6 and 15.2 angstroms,respectively.The photoluminescence (PL) efficiencies of the CdSe/CNT nanohybrids increase significantly with the increase of the shell thickness,which is attributed to a distance-dependent charge transfer mechanism.This work demonstrates a simple mean for fine tuning the PL properties and gains new insights to the charge transfer in such CdSe/CNT nanostructures.3.The energy transfer with in a series of nanocomposites consisting molecular wires and CdSe Qds were investigated.Thiol-substituted dendrimer encapsulated "core-shell" molecular wires(Den-OPE) were used to functionalize CdSe QDs. Attachment of the molecular wires to the CdSe QDs resulted in little change to the electronic structure of the molecular wires,as shown by the absorption spectra.The emission spectra of the CdSe/Den-OPE composite showed that Den-OPE molecular wires emission was quenched,while the emission of CdSe QDs was enhanced due to either an electron or an energy transfer mechanism.4.A multifunctional drug delivery system for the anti-cancer drug genistein has been devised,which is based on covalently attaching genistein onto the Fe₃O₄ nanoparticles coated with cross-linked carboxymethylated chitosan(CMCH).The nano-conjugate shows good water solubility and superparamagnetic properties.The effects of genistein and Fe₃O₄-CMCH-genistein nano-conjugate on the proliferation and apoptosis of gastric cancer cell line SGC-7901 were investigated by MTT assay and flow cytometry.Compared with free genistein,the nano-conjugate shows much higher anti-tumor effect.This drug delivery system is promising for future multifunctional chemotherapeutic application that combines drug release and magnetic hyperthermia therapy.