Date of Award


Degree Type


Degree Name

Master of Engineering Science


Chemical and Biochemical Engineering


Dr. Jin Zhang


Design and fabrication of biocompatible nanomaterials with multifunctional properties is one of the most powerful paradigms in the nanobiotechnology field. Recently, fluorescent and magnetic silica-based nanoparticles (NPs) have received much attention because of its biocompatible and engineerable-surface. Mesoporous silica nanoparticles first produced in 1990s become an alternative excellent candidate to load biomolecules, organic dyes, and magnetic nanocores due to their special porous structure. The challenges of developing such multifunctional nanoparticles include: poor cell uptake due to aggregation of NPs, low fluorescent signal due to poor loading rate, serious photobleaching due to improper encapsulation, and unsatisfied magnetic properties due to very small and non-uniform magnetic core. Herein, my research goal is to design, fabricate, and biofunctionalize the new biocompatible multifunctional mesoporous silica-based NPs. I have synthesized both the hydrophilic and hydrophobie dyes loaded in mesoporous silica nanoparticles (MSNs). Here, a rhodamine derivative, TRITC-dextran (tetramethyl rhodamine isothiocyanate conjugated dextran), the hydrophilic dye, was loaded in MSNs through the water-in-oil microemulsion method, while, the hydrophobie dye, FITC (fluorescein isothiocyanate), was loaded in MSNs by using a sol-gel method. The FITC covalently bonded with MSNs shows better performance in term of photostability. To increase the cell uptake, the surface of FITC loaded MSNs were further modified by introducing phosphate functional groups which form stable re-dispersion by efficiently minimized the aggregation of fluorescent MSNs. The average particle size of fluorescent MSNs was 45-64 nm. It was found that the surface modification significantly improves the dye loading efficiency, photostability, and the dendritic cells uptake without posing any cytotoxicity issue. In addition, a new one-pot synthesis method was developed to coat the superparamagnetic magnetite (Fe3O4) core with the fluorescent MSNs shell. Transmission electron microscopy (TEM), laser confocal scanning microscopy (LCSM), fluorescence microscopy, fluorospectrometry, X-ray diffraction (XRD), energy dispersive X-ray (EDX), superconducting quantum interface device (SQUID) magnetometer were exploited to study the structure and properties of the fluorescent-magnetic multifunctional MSNs. The interaction between the multifunctional silica based NPs and cells were studied in vitro by using the LCSM and flow cytometry. Furthermore, core-shell nanoparticles were conjugated with gentamicin (an aminoglycoside antibiotic) through glutaraldehyde. TEM micrographs reveal the successful capturing of Gram negative bacterial Escherichia coli (E. coli). It is expected that these multifunctional NPs can be used in bio-imaging and pathogen capture.



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