| 研究実績の概要 |
Heretofore, we have developed a simple and low-cost method using inkjet printing technology to fabricate a paper-based copper ion sensor for both visible and quantitative detection. In the visible detection, it was observed that the color of quinizarin, which is a kind of fluorescent dye, on a paper-based sensor changed from yellow to light purple, indicating that the sensor has a function to detect Cu2+ of as low as 2 ppm, which is the maximum amount allowed according to World Health Organization for drinking water. It provides the potential application for nonprofessional people to have the quick on-site detection. In the quantitative detection, based on the relationship of surface fluorescence intensity and copper ion concentration, highly sensitive detection of ppm and ppb level could be achieved, revealing the application in lab analysis. The paper-based sensor could provide accurate measurement of Cu2+ concentration coupled with the fluorescence spectroscopy. High-sensitivity multi-range measurement could be achieved in the range of 0-3 ppm and 0-300 ppb.
In the research, instead of the original plan, an alternatively proposed method using quinizarin was used to fabricate the paper-based sensor. However, it was proven to be a more successful fabrication method, because it's low-cost, highly selective and sensitive and possible for both visible and quantitative detection, which was impossible and not expected in the original research plan. Thus, the dual-functional paper-based sensor is believed to hold great potential for both non-professional users and researchers.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
1: 当初の計画以上に進展している
理由
According to the initial research plan, in the first and second year, my research was aimed to finish the synthesis and examination of poly(N-vinyl imidazole) (PVI), surface modification of cellulose fibers and fabrication and evaluation of a novel paper-based copper ion sensor. In the examination of PVI, we found that the polymer could react with Cu2+ as we expected. However, the reaction was unexpectedly affected by other inorganic salts, resulting in impossibility of the practical application. Therefore, an alternative strategy was proposed.
In the alternative method, we redesigned the concept to fabricate a paper-based sensor for the final user-friendly and practical application. We simplified the fabrication process, but the paper-based sensor was more functional and practical. The developed paper-based sensor could detect copper ion in water visually and quantitatively. Especially in the visible detection, the sensitivity was proven to be 2 ppm, which is the maximum amount allowed according to World Health Organization for drinking water. It is believed to be useful for nonprofessional people to have on-site water security check. And compared to ICP-AES and AAS, the quantitative detection coupled with fluorescence spectroscopy is also a simpler alternative method for copper ion concentration measurement in laboratory. Therefore, based on our new strategy, the fabrication is much simpler, but the sensor is more functional and user-friendly than we initially expected. And it’s also on the process to apply a patent and submit a manuscript for publication.
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| 今後の研究の推進方策 |
In the research of paper-based sensor, it is believe that quinizarin could adsorb onto cellulose fibers through non-covalent bondings, including hydrogen bonding, hydrophobic force and CH/π interaction. In the new research, it is planned to primarily study the affinity of quinizarin adsorption onto cellulose fibers. And based on the result, a cellulosic absorbent filter modified using quinizarin will be prepared for Cu2+ removal. Eventually, the new modification strategy through non-covalent bonding will be evaluated and compared with common methods, such as esterification, etherification and etc.
Main factors to study includes: 1. Affinity analysis of quinizarin adsorption onto cellulose fibers; 2. Wet-strength improvement by crosslinking agent to prevent breakage of fiber network in water; 3. More porous network structure by addition of cellulose nanofibers; 4. Batch adsorption study of Cu2+ removal.
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