Optical Bio-imaging Research Assisted With Some Nanoparticles With Desired Spectral Properties

Biophotonics is an exciting frontier which involves a fusion of advanced photonics and biology technologies.Since it has special status and great potentials in biomedical areas, biophotonics is becoming a hot area in recent life science research studies.As the development of nanomaterial technology,a new research direction called nano-bio-photonics is born in biophotonics area.Quantum dots,mesoporous silica nanoparticles,up-conversion nano-phosphors and gold nanorods are four novel nanoparticles with unique spectral characteristics and excellent chemical stabilities,and they have wide applications in biophotonics area.This dissertation detaiiedly discussed their optical properties,chemical properties and biocompatibilities,and finished a lot of relevant research work in optical bioimaging.Besides,we extended some work to optical biotherapy.The detail content is as follows:1.CdSe/CdS/ZnS quantum dots(QDs)/quantum rods(QRs) with unique core/shell structures were synthesized.A novel surface modification method was proposed to transfer the hydrophobic QDs/QRs to hydrophilic,and increase the efficiency of bioconjugation and their biocompatibilities.Transferrins and antibodies were conjugated with QDs/QRs,and the bioconjugated QDs/QRs could target the pancreatic cancers specifically.Confocal microscopy was used for the single/two-photon fluorescence imaging,which is helpful to detect and diagnose the pancreatic cancer cells treated with the QDs/QRs.A facile microemulsion method was used to encapsulate QDs with silica shell and graft carboxyl groups on their surfaces.The carboxyl groups are helpful to decrease the nonspecific uptake of QDs in cancer cells,and increase the efficiency of bioconjugation.Transferrin conjugated QDs have the ability to specifically target the cancer cells,and fluorescence microscopy was used for the fluorescence imaging to detect the cancer cells.2.Mesoporous silica nanoparticles were used to encapsulate the organic fluophores,and the whole nanoparticles are water soluble and have good chemical stability and biocompatibility. Biomolecules(like transferring and folic acid) were covalently conjugated with the mesoporous silica nanoparticles,and the bioconjugated nanoparticles could target the cancers specifically. Fluorescence microscopy was used for the fluorescence imaging,to detect and diagnose the cancer cells.Photodynamic therapy(PDT) drugs were encapsulated by mesoporous silica nanoparticles,and the whole nanoparticles are water soluble,and not easy to aggregate in biological environment.Amino groups were grafted on the surfaces of nanoparticles,and transferrins were then bio-conjugated with nanoparticles.Mesoporous silica nanoparticles were used to non-specifically and specifically stain the cancer cells for the fluorescence imaging,and the corresponding in-vitro PDT were also carried out in both situations.Because of the mesoporous silica encapsulation,the existed problems of PDT drugs,like water solubility, aggregation,and specific targeting,were overcome.Mesoporous silica nanoparticles were used to encapsulate the organic QDs,and amino groups were then grafted on the surfaces of nanoparticles.The whole nanoparticles are water soluble and have good chemical stability and cell targeting ability.Total internal reflection fluorescence(TIRF) microscopy,which has the "optical sectioning" ability,was used to do the TIRF imaging and long time dynamic observation of cancer membrane,treated with the QDs doped mesoporous silica nanoparticles.3.Up-conversion nano-phosphors were surface modified and bio-conjugated,and an up-conversion fluorescence microscopy was also built up,which are very helpful for the future studies of up-conversion fluorescence bioimaging.4.Different types of gold nanorods were synthesized,and conjugated with transferrin. Bio-conjugated gold nanorods could be used as scattering contrast reagents for cell imaging. Dark field scattering microscopy was utilized to observe the uptake of gold nanorods in the cancer cells for diagnosis and detection.Gold nanorods have high absorption properties.They can be used as absorption contrast reagents in optical coherent tomography(OCT) to increase the signal intensity and detection sensitivity.A new contrast mechanism(differential-absorption OCT imaging) based on the strong absorption of GNRs was proposed.It can retrieve the absorption information from conventional scattering information of OCT.