| With the continuous development of nanotechnology, various novel nanomaterials are constantly emerging, in which the multifunctional nanomaterials are attracting special attention. The multifunctional nanomaterials, in which two or more components are incorporated to give multifunctional capabilities, have been proved to be of great potential in the fields of biomedicine, biotechnology, and so on. In this thesis, three typical nanomaterials (Fe3O4nanoparticles, carbon dots and palygorskite), were separately used to assemble multifunctional nanocomposites, while the applications of the novel nanocomposites in biology were further performed.(1) Four-component nanoparticals containing a SiO2-coated Fe3O4magnetite core, luminescent europium (Ⅲ) complex, and PEI surface layer have been synthesized:(1) preparation of uniform magnetite Fe3O4NPs;(2) preparation of Fe3O4@SiO2structure via a sol-gel approach;(3) the coupling the Eu3+luminescent complex onto the Fe3O4@SiO2matrix;(4) the adsorption of PEI onto the naoncomposites by hydrogen-bond mediated self-assembly method. The obtained multifunctional nanocomposites exhibited superparamagnetic behavior, high fluorescence intensity, color purity, and could be excited by visible light, with a wide excitation wavelength range from UV to visible light. When incubated with HeLa cells at37℃, the fluorescence of the naoncomposites could be observed on the cell membrane. This research had good application prospects in biology, and supplied a new way of thinking for the assembly and surface hydrophilic modification of multifunctional nanocomposites.(2) Cow milk-derived carbon dots (CMCD) were separated using a simple and cheap "gradient extraction" method, which was applied for the first time in nanomaterials’ separation. The surface-polarity of the extractive CMCD correlated with the polarity of the extraction solvent. Interestingly, the surface polarity could affect the photoluminescence (PL) properties of the CMCD:As the surface polarity increased, a red-shift PL of CMCD was observed, the excitation-dependent PL became more and more obvious, moreover, the PL lifetime became longer and longer, while the related PL mechanism of CD was discussed in detail. To further demonstrate the practical importance of separating CD by their surface polarity, multifunctional applications of the CMCD based on extraction was described, including the use of amphiphilic CMCD as the precursor in fabricating novel antibacterial films, and the use of the hydrophilic ones as pH sensor based on their PL properties. Our work provides a new insight into the PL mechanism of CD and is expected to pave a new way to study the surface chemistry and applications of carbon nanomaterials.(3) Palygorskite (Pal), a natural clay, grafted by polyethyleneimine (PEI) via the coupling grafting method, has further been modified by introducing both fluorescein isothiocyanate (FI) and folic acid (FA), with the aim of specifically targeting and detecting cancer cells. The formed Pal-PEI-FI-FA nanocomposites were nontoxic up to a concentration of300μg·mL-1and further could be specially taken up by HeLa cells via FA receptor-mediated endocytosis shown by confocal microscopy and inductively coupled plasma optical emission spectroscopy (ICP-OES) data. Therefore, the novel Pal nanocomposite is considered to be of great potential for biomedical applications. Furthermore, this research would provide references to the modification with polymer surface and applications of nanomaterials.(4) Pal is a kind of mine which is quite abundant and cheap, while zinc lignosulfonate is a derivative of lignin which is a common waste product of the papermaking industry. In this section, using both Pal and zinc lignosulfonate as the matrix, a novel multifunctional super absorbent polymer (SAP) nanocomposite was synthesized by free-radical solution polymerization. The water absorbency of the novel SAP nanocomposite which had reached the national standard exhibited an absorption of320g H2O/g, while the zinc sustained-release time is more than30days. The influence of the multifunctional nanocomposite on germinating percentage of corn was further determined, which showed that the nanocomposite could increase the germinating percentage of corn by5.4%. Therefore, this novel multifunctional SAP nanocomposite is considered to be important for a variety of applications in agro-forestry planting system, and other biotechnologies. |
PDF Full Text Request