| 研究実績の概要 |
Fluorescent nanoparticles (biodots) of several nm in size were synthesized from polymeric and monomeric nucleic acids by hydrothermal (HT) treatment. Formation of biodots proceeds by degradation of ribose sugar, whereas depurination,
depyrimidation and consequent condensation and polymerization of nucleobases result in the formation of fluorescent nanoparticles. HT treatment of nucleic acids containing purine nucleobases yielded biodots that are over 50 times brighter compared to the biodots prepared from precursors containing pyrimidine nucleobases. The brightest biodots prepared from AMP nucleotide had the highest quantum yield of ca. 30%.
Microwave reaction can be also used to prepare fluorescent products from DNA and nucleotides, yet their fluorescent properties were inferior compared to HT reaction products.
Biodots had high affinity to Hg2+, Ag+ and Cu2+, which was utilized for the sensing of these heavy metal ions. Biodots prepared from individual nucleotides showed better selectivity to Hg2+ ions and a linear dependence on Hg2+ concentration in a broad concentration range. In addition, biodots could be used to make paper-based sensor strips for detecting metal ions in aqueous solutions that can be used for developing simple metal ion indicators for analytical and environmental applications.
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| 今後の研究の推進方策 |
In the the second year of the proposed research, the main focus will be given to pyrolytic treatment of DNA and DNA-containing materials to prepare carbon nanomaterilas. Initial synthetic pathways to investigate are pyrolysis and combustion. A variety of processing conditions will be examined, including atmospheric composition, processing temperature and time to obtain graphitic carbon or a similar product. DNA-derived products will be characterized to determine chemical composition (FTIR, elemental analysis), functional groups (NMR) nanostructure (XRD, Raman), morphology (TEM, SEM), electronic (UV/Vis diffuse reflectance), and fluorescence properties (fluorescence spectroscopy and microscopy). The products of DNA materials' pyrolytic treatment will be compared to carbon nanomaterials obtained from more common cellulosic precursors.
The application of DNA-derived biochar will be studied for adsorption and separation of various pollutants relevant to environmental systems. Standard batch adsorption experiments will be performed for metal ions (Hg2+, Cd2+, Pb2+, etc.) and organic contaminants (pharmaceuticals such as ibuprofen, diclofenac, etc.) and compared with the adsorption property of the original DNA materials. Kinetic analysis of adsorption isotherm studies will be performed to make comparison with activated carbon and other commonly used adsorbents.
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