| Summary: | 博士 === 國立清華大學 === 化學系 === 104 === In the recent years, noble metal nanoparticles have considerable attention owing to their fascinating optical, electrical and catalytic properties which makes them as potential candidates for various applications including, biomedical, catalysis and sensors. Among various morphologies being reported, anisotropic branch shaped gold nanoarchitechures are of utmost importance due to their unique morphology with broad and tunable localized surface plasmon resonance (LSPR) absorption in the near infra-red (NIR) region of the electromagnetic spectrum. In the first chapter of the thesis, we have primarily focused on the seed-mediated surfactant directed synthesis and its mechanistic investigation of the formation of multi-branch shaped Au nanoechinus using a novel twin tailed cationic surfactant (DC14TAB). In the following chapters, we have also utilized the unique properties of Au nanoechinus in various biomedical applications such as photodynamic/ photothermal therapy of tumors as well as multimodal imaging in broad dimensions.
In the recent years, phototherapy has attracted considerable attention as a powerful technique for treating cancers as well as malignant tumors with minimal invasiveness. Photodynamic therapy (PDT) and photothermal therapy (PTT) are two major phototherapeutic approaches, which require absorption of incoming light by a photosensitizer/reagent to generate reactive oxygen species (ROS) and heat for killing cancer cells, respectively. In order to have a deeper penetration of the incoming light, it is mandatory for a phototherapeutic reagent to absorb the tissue transparent near infra-red (NIR) light, where the biological components have minimum absorbance. The first NIR biological window was located in the region, 650 – 900 nm and the second NIR biological window at 1000 – 1350 nm, which therefore provides low scattering, excellent tissue penetration depths and poor autofluorescence. In the second chapter, we have shown that the photosensitization of singlet O2 from Au NEs can be achieved upon NIR light excitation in both the biological windows (915 and 1064 nm), and subsequently can exert photodynamic therapeutic effects for the destruction of cancer cells/tumors.
Cancer is one of the major diseases leading to human deaths. Complete destruction of deep tissue-buried tumors using non-invasive therapies is a grand challenge in clinical cancer treatments. Many therapeutic modalities were developed to tackle this problem, but only partial tumor suppression or delay growths were usually achieved. In the third chapter, we have demonstrated that complete destruction of deep tissue-buried tumors can be achieved by the combination of gold nanoechinus (Au NEs)-mediated photodynamic therapy (PDT) and gene silencing under ultra-low doses of near infra-red (NIR) light irradiation (915 nm, 340 mW/cm2; 1064 nm, 420 mW/cm2) in the first and second biological windows. Our findings pave out a new direction for the therapeutic design to treat deeply seated tumors in future cancer treatments.
In order to accomplish the scenario of modern theranostics, it is better for the nanomaterials to serve the purpose of intrinsic bioimaging properties in addition to the therapeutic capabilities. Bioimaging is of ultimate importance to have detail study in the underlying complex cellular and pathological events occurring inside body which gives appropriate information about the detection, status and treatment of various fatal diseases. In the last chapter, we have explored that multi-branched gold nanoechinus can serve as a new class of triple modal bioimaging reagent for NIR-to-NIR up-and down-conversion processes as well as photoacoustic imaging. Taken altogether, we have thoroughly explored the optical properties of the multi-branched gold nanoechinus in various biomedical applications for diagnosis and treatment of cancers.
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