Multimodal Imaging of Silver Nanoclusters
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Recent developments in Nanobiotechnology have given rise to a novel brand of fluorescent labels, fluorescent metal nanoclusters, e.g., gold and silver nanoclusters. Generally, high atomic number elements such as silver can attenuate more X-ray and consider as label in X-ray microtomography. Features such as ultra-small size, good biocompatibility, non-toxicity and photo-stability made nanoclusters more attractive as a fluorescent label than conventional fluorophores dye in biological imaging. The core concept of this thesis is to analyze silver nanoclusters as contrast agent by the multimodal imaging approaches of X-ray microtomography (MicroCT) and Optical Projection Tomography (OPT). To estimate the absorption and relation of X-ray and fluorescent signal by different concentrations of silver nanoclusters in samples. AgNCs-Agar with different concentrations of AgNCs, diluted with agar and water and filter paper coated with silver nanoclusters with different dipping time were studied in this work. The imaging implementation divided into three parts: 1. MicroCT imaging of samples (both AgNC-Agar and filter paper), 2. Optical imaging of AgNC-Agar samples by both fluorescent and bright-field modes. 3. MicroCT imaging of samples which were imaged by OPT first. Afterward, quantitative approach employed to both microCT and optical images to evaluate the relation between X-ray energy and light intensity with different concentrations of AgNCs to assess the amount of X-ray and light absorption by samples. Ideally, higher ratio of AgNCs revealed brighter microCT images due to more X-ray absorption. In sum, our results showed that the tested silver nanoclusters can be used as a label in both X-ray microtomography and fluorescent OPT since they show the contrast in X-ray and optical images. Moreover, depicted graphs demonstrate the linear correlation between data from images of both modalities and different amounts of silver material.