Preparation Of Bio-nanoparticles And Its Applications In Drug Carriers And Magnetic Fluorescent Probes

This thesis describes current approaches for the preparation of biodegradable polymers nanoparticles and their applications research in medical field. Two kinds of natural macromolecules biodegradable polymers, chitosan and starch, were used in this experiments. Firstly, chitosan microsphere(CSM)was prepared and used as antibacterial drug carrier; Secondly, 5-Fluorouracil-loaded chitosan nano-se micros- phere was prepared and the synergetic action of 5-Fu and nano-se was studied; Thirdly, magnetic starch nanoparticles was synthesized and then modified with Poly-L- Lysine(PLL) and fluorescein isothiocynate(FITC) to form fluorescent/- magnetic bifunctional starch nanoparticle probes. This thesis includes three major parts as follows:1. Chitosan microsphere was used as drug delivery for antibacterial property. Norfloxacin(NFX)-chitosan(CS) microsphere(NFX-CSM) was prepared by using water-soluble CS and NFX with emulsification and cross-linking process. Orthogonal design based on 4 factors: the feed ratio of CS to NFX, dosage of crosslinker, stirring speed and temperature, was studied to determine the optimum preparing technique of microsphere. NFX-CSM was characterized via scanning electron microscope, Fourier transform infrared spectrometer and Zeta potential measurement. The release speed of NFX was determined under different pH conditions with the dissolution apparatus. Effects of dosage of crosslinker and feed ratio of CS to NFX on drug release were examined. Antibacterial property was tested while E.coli and NFX-CSM were co-cultured. The results show that NFX-CSM has good shape and dispersibility with the average particle size of about 4μm; the drug loading and drug encapsulation efficiency of NFX-CSM are 4.9% and 42.8%, respectively; the sustained release is remarkable under different pH conditions; the drug release speed is decreased with the increase of feed ratio of CS to NFX and dosage of crosslinker. The antibacterial effect of NFX is improved obviously in the synergetic action of CS microsphere.2. Chitosan microsphere was used as drug carrier for anti-tumor properties. 5-Fu chitosan mirospere was prepared in emulsion by using glutaradelhyde as cross-linking, Span-20 mixture as emulsifier, liquid olefin as oil phase, and soluble chitosan as carrier. Then, 5-Fu chitosan microspere was used as template, PEG for steady substance, 5-Fluorouracil-loaded chitosan nano-se microsphere after Vc deoxidize Na2SeO3. Then MTT analysis was used to compare the synergetic action of 5-Fu and nano-se in 5-Fluorouracil-loaded chitosan nano-se microsphere to separateness. The results show that the size is about of 100 nm and the potent is about 50 mV;there is a very strong force between 5-Fu and chitosan. The preparation is very good and the condition is simple and convenient. The microsphere not only contain the perfect coeffect of 5-Fu and nanose, but also protect 5-Fu and decrease the toxicity.3. Magnetic starch nanoparticles(MSNP) was synthesized in water-in-oil microe- mulsion under room temperature, and soluble starch and iron oxide nanoparticles were used as raw materials and POCl3 as crosslinking agent. MSNP was characterized via TEM, FTIR, Zeta potential system, TGA and VSM. The average diameter of MSNP is about of 220 nm, with uniform in size, well dispersed and magnetic resonance, and the saturation magnetization was 3.64 emu/g.MSNP was coated with Poly-L-Lysine (PLL). Then the surface of PLL-MSNP was combined with fluorescein isothiocyn- ate(FITC). Results show that fluorescent/ magnetic starch nanoparticles(FMSNP) has more stable against photobleaching capability in comparison with free FITC, with low bio-toxicity, and certain function of magnetic separatation. It is expected that FMSNP would be bifunctional nano-material including fluorescence labeling and magnetic separatation.In conclusion, the natural macromolecule polymer nanoparticles from chitosan and starch, are provided with biodegradable, low-toxicity performance, simultaneity, according their active chemical property, they can be applied as a natural material in bio-medical field.