| In recent years, water-soluble conjugated materials have attracted a lot of attention in the field of fluorescence sensing, biological imaging, diagnosis and therapy owing to their strong ability to absorb light, molecular wire effect, supramolecular self-assembly properties,good biocompatibility and many other advantages. Currently, some materials, such as organic fluorescent dyes, fluorescent quantum dots and gold nanoparticles, have been widely used for fluorescence imaging. However, organic fluorescent dyes are not suitable for long-time observation due to photobleaching and the quantum dots exhibit high cytotoxicity. Water-soluble conjugated materials are expected to have broad applications in biological imaging and nano-drug delivery because of its good fluorescence efficiency, light stability, low cytotoxicity and ability to form nano-materials by supramolecular self-assembly. At present, water-soluble conjugated materials need to strengthen specific recognition in the application of biosensor. In the applications of biological imaging and nano-drug delivery, it need to obtain the materials whose excitation and emission are in red/NIR wave band, and improve targeting effects. Therefore, we introduced hyaluronic acid(HA) into the sensing and imaging system to simulate the multi-point recognition mode of biological systems by the specific interaction of hyaluronic acid and its receptor CD44 protein. Moreover, based on the phenomena of the significantly increased CD44 expression in the tumor cells, we explored the applications in tumor-targeting cell imaging and diagnosis.In this thesis, a water-soluble conjugated polymer, a water-soluble conjugated oligomer, hyaluronic acid and the anticancer drug doxorubicin(Dox) were used as raw materials. We designed and prepared some composite nanoparticles for biosensing, tumor-targeting cell imaging and drug delivery. The main research work is as follows:(1) We established a new method to quantitatively detect hyaluronidase using cationic conjugated polymers/HA composite probe. Cationic conjugated polymers and hyaluronic acid combined with doxorubicin formed complex with the sizes of 30-50 nm through electrostatic attraction and hydrophobic interactions. In this complex, due to the electron transfer, the fluorescence of conjugated polymer was quenched by doxorubicin and in "turn-off" state. When adding hyaluronidase which can hydrolyze hyaluronic acid into fragments, the electrostatic attraction between hyaluronic acid and conjugated polymer was weaken and the doxorubicin was released, thus the fluorescent of conjugated polymer became in "turn-on" state. This method was simple, fast and has good sensitivity and specificity, the detection limit can reach 0.075 U/mL, and we employed it in detecting the content of hyaluronidase in human urine. We also used transmission electron microscopy to characterize the morphology and size of this complex. Moreover, we successfully applied it to tumor-targeting drug delivery and cell imaging of Hela cells through the CD44 receptor-mediated targeting into tumor cells.(2) Using 2,1,3-benzothiadiazole as an electron acceptor, fluorene with side chains containing hydrophilic carboxyl group as an electron donor, styrene as a conjugated bridge, we designed and synthesized water-soluble conjugated oligomer with D-π-A-π-D structure, whose maximum fluorescence emission peak was at 580 nm. We attached this conjugate oligomer molecules to hyaluronic acid by cysteamine, and prepared water-soluble conjugated oligomer-hyaluronic acid/doxorubicin(M1-HA/Dox) nanoparticles by self-assembly through the hydrophobic interactions among the conjugated structure of the oligomer molecules, doxorubicin and HA. The overexpressed hyaluronidase and glutathione in tumor cells were able to degrade hyaluronic acid and the disulfide bond connecting M1 and HA, and tumor-targeting fluorescence imaging and controlled drug release can be achieved at the same time. |
PDF Full Text Request