• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.281.2-281.2
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• 2013

Since heavy metal ions included in water or food resources have critical effects on human health, highly sensitive, rapid and selective analysis for heavy metal detection has been extensively explored by means of electrochemical, optical and colorimetric methods. For example, quantum dots (QDs), such as semiconductor QDs, have received enormous attention due to extraordinary optical properties including high fluorescence intensity and its narrow emission peaks, and have been utilized for heavy metal ion detection. However, the semiconductor QDs have a drawback of serious toxicity derived from cadmium, lead and other lethal elements, thereby limiting its application in the environmental screening system. On the other hand, Graphene oxide (GO) has proven its superlative properties of biocompatibility, unique photoluminescence (PL), good quenching efficiency and facile surface modification. Recently, the size of GO was controlled to a few nanometers, enhancing its optical properties to be applied for biological or chemical sensors. Interestingly, the presence of various oxygenous functional groups of GO contributes to opening the band gap of graphene, resulting in a unique PL emission pattern, and the control of the sp2 domain in the sp3 matrix of GO can tune the PL intensity as well as the PL emission wavelength. Herein, we reported a photoluminescent GO array on which heavy metal ion-specific DNA aptamers were immobilized, and sensitive and multiplex heavy metal ion detection was performed utilizing fluorescence resonance energy transfer (FRET) between the photoluminescent monolayered GO and the captured metal ion.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.85-85
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• 2013

Label-free, sensitive and selective detection methods with high spatial resolution are critically required for future applications in chemical sensor, biological sensor, and nanospectroscopic imaging. Here I describe the development of Plasmon Resonance Energy Transfer (PRET)-based molecular imaging in living cells as the first demonstration of intracellular imaging with PRET-based nanospectroscopy. In-vivo PRET imaging relied on the overlap between plasmon resonance frequency of gold nanoplasmonic probe (GNP) and absorption peak frequencies of conjugated molecules, which leads to create 'quantized quenching dips' in Rayleigh scattering spectrum of GNP. The position of these dips exactly matched with the absorption peaks of target molecules. As another innovative application of PRET, I present a highly selective and sensitive detection of metal ions by creating conjugated metal-ligand complexes on a single GNP. In addition to conferring high spatial resolution due to the small size of the metal ion probes (50 nm in diameter), this method is 100 to 1,000 folds more sensitive than organic reporter-based methods. Moreover, this technique achieves high selectivity due to the selective formation of Cu2+complexes and selective resonant quenching of GNP by the conjugated complexes. Since many metal ion ligand complexes generate new absorption peak due to the d-d transition in the metal ligand complex when a specific metal ion is inserted into the complex, we can match with the scattering frequency of nanoplasmonic metal ligand systems and the new absorption peak.

• 한국지하수토양환경학회지:지하수토양환경
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• 제21권3호
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• pp.1-5
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• 2016

Rhodamine B Hydrazide as a novel fluorescent and colorimetric probe exhibiting remarkably selective fluorescence enhancement toward Hg²⁺ ion over other 16 metal ions is herein introduced. The probe reacts with Hg²⁺ ion followed by its spirolactam ring-opening to give a remarkable enhancement of absorption maximum at 550 nm as well as an enhanced fluorescence intensity at 580 nm in aqueous media. Upon titration with Hg²⁺ ion in various concentration of 10~200 uM, we found that the probe shows a marked color change from colorless to pink, enabling naked-eye detection toward mercury ion. In addition, in the presence of Hg²⁺ ion, the probe gave rise to change from non-florescence to strong orange fluorescence (Off-On) with a good linearity of R²=0.97. This preliminary results demonstrate that the fluorescent chemosensor we herein introduced can open a new strategy for marked selective and sensitive detection of mercury ions in contaminated soil containing various metal ions.

• 청정기술
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• 제11권2호
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• pp.69-74
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• 2005

본 연구에서는 AFM 양극산화법을 이용하여 서브마이크로 수준의 패턴을 구성하였다. 자기조립법으로 제조한 MPTMS/Si(100) 기질 위에 AFM 양극산화법으로 패턴을 형성하였고, 비에칭법을 이용하여 아민그룹을 지닌 기능기를 고정시켰다. 금속전극으로는 Frens 방법으로 제조한 금나노입자를 이용하였다. 금속이온의 흡착에 따른 전도도는 근거리의 경우 coherent tunneling에 의존하지만, 원거리 전극에서는 incoherent tunneling에 의존한다. 전극의 간격이 가까울수록 저항이 감소하여 센서의 감도와 최소검출능을 개선할 수 있었다. 또한 다중기능성을 부여하여 센서의 선택도를 부여하였으며, 패턴의 크기에 따른 최소검출농도를 낮출 수 있음을 확인하였다.

• 센서학회지
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• 제33권5호
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• pp.366-372
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• 2024

In this study, we present a novel approach to improve electrochemical heavy metal ion (HMI) sensing responses via post-synthetic modification of carbon nanotube-based metal-organic framework (MOF) nanocomposites with a Schiff base. UiO66-NH₂ was employed as the MOF and incorporated with multi-walled carbon nanotubes (MWCNT) through in-situ growth, enhancing the electrical conductivity of the MWCNT-UiO66-NH₂ composite. Subsequently, the Schiff base, which has been proven to be an excellent ligand for metal ion detection, was functionalized onto MWCNT-UiO66-NH₂ via post-synthetic modification to improve its HMI absorption capacity. To evaluate the effect of the Schiff base on HMI detection capacity, electrochemical sensing of Cd²⁺, Pb²⁺, Cu²⁺, and Hg²⁺ was performed in an aqueous solution utilizing the MWCNT-UiO66-Schiff modified electrode as well as the bare electrode. Individual differential pulse anodic stripping voltammetry results revealed that the modified electrode with MWCNT-UiO66-Schiff exhibited increased HMI sensing properties, especially with 1.82-fold improvement in average oxidation currents toward 10 µM of Cu²⁺ compared to that for a bare glassy carbon electrode. The selective Cu²⁺-sensing properties of MWCNT-UiO66-Schiff were reflected in the highly selective Cu²-binding affinity of the Schiff base-containing model molecules compared to those of Cd²⁺, Hg²⁺, and Pb²⁺. Our work provides a new strategy for improving the sensing properties of electrochemical HMI sensors by the post-synthetic modification of MWCNT-UiO66 with a Schiff base.

• Journal of Microbiology and Biotechnology
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• 제13권3호
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• pp.373-377
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• 2003

Various groups of industrial and agricultural pollutants (heavy metal ions, cyanides, and pesticides) can be detected by enzymes. Since heavy metal ions inhibit urease, cyanides inhibit peroxidase, organophosphorus and carbamate pesticides inhibit butyrylcholinesterase, these enzymes were co-immobilized into a bovine serum albumin gel on the surface of an ion-sensitive field effect transistor to create a bioprobe that is sensitive to the compounds mentioned above. The sensitivity of the present sensor towards KCN corresponded to $1\;\mu\textrm{M}$ with 1 min of incubation time. The detection limits for Hg(II) ions and the pesticide carbofuran were 0.1 and $0.5\;\mu\textrm{M}$, respectively, when a 10 min sensor incubation time in contaminated samples was chosen. The total time for determining the concentrations of all species mentioned did not exceed 20 min.

• 한국염색가공학회지
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• 제32권4호
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• pp.185-192
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• 2020

A novel binding site for metal ion made by designing molecule with tetrazolo quinoline with hydrazine carboxamide (TQC) and the designed molecule successfully synthesized. The probe works by selectively detecting Al3+ ion via both fluorimetric and colorimetric approach. The probe's effectiveness towards aluminium ion detection is highly sensitive and selective with no substantial interference with other competing ions. The added Al3+ ion to TQC fetched a rapid change of visual color to yellow from colorless, also the response of fluorescence turn-on. The fluorescence turn-on and color change visibly by the probe TQC with Al3+ ion credited to the ICT phenomenon (intramolecular charge-transfer transition). The likely interaction of the probe with aluminium ion has also been there predicted from ESI-MS spectral analysis results. The usefulness of the probe confirmed by practical utility by making a test kit to monitor Al3+ ion in water which showed a naked eye detection by notable color change.

• Bulletin of the Korean Chemical Society
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• 제25권10호
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• pp.1465-1470
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• 2004

A short and efficient synthesis, solvent extraction and potentiometric measurements of new thiazole-containing naphtho-crown ethers are reported. The naphthalene moiety enhances the ammonium ion selectivity over potassium ion. The selectivity of ${NH_4}^+/K^+$ follows the trend $3\;{\approx}\;2\;>\;1$, indicating that the differences in conformational changes of 2 and 3 in forming ammonium complexes affect little on the resulting ammonium/potassium extraction selectivity ratio. The ammonium ion-selective electrodes were prepared with noctylphenyl ether plasticized poly(vinyl chloride) membranes containing 1-4 the effect of one naphthalene unit introduced on either right (2) or left (3) side of thiazolo-crown ether on their potentiometric properties (e.g., ammonium ion selectivity over other cations, response slopes, and detection limits) were not apparent. However, the ammonium ion selectivity of 1, 2 and 3 over other alkali metal and alkaline earth metal cations is 10-100 times higher than that of nonactin.

• 청정기술
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• 제28권4호
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• pp.323-330
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• 2022

미세유체 종이-기반 분석 장치는 최근 현장 진단 및 환경 물질 감지를 포함한 다양한 적용가능성으로 주목을 받고 있다. 본 연구는 적은 비용과 간단한 검출 방법으로 중금속을 빠르게 검출할 수 있는 3D-μPAD를 제작하기 위해 PDMS 양면 인쇄 방법을 제안하였다. 3D-μPAD 디자인은 레이저 커팅으로 아크릴 스탬프에 적용할 수 있으며, 제작된 스탬프에 PDMS 고분자를 스핀 코팅 후 양면접촉인쇄 방식 도입을 통해 3차원 형태의 소수성 장벽 형성에 필요한 조건을 확인하였다. 구체적으로 소수성 장벽 형성 조건인 고분자 농도, 스핀 코팅 속도 및 접촉 시간에 따라 PDMS 소수성 장벽 면적과 친수성 채널의 면적 변화를 분석함으로써 3D-μPAD 제작 공정 조건 최적화를 수행하였다. 최적화된 μPAD로 니켈, 구리, 수은 이온, pH를 다양한 농도에서 검출하였고 이를 ImageJ 프로그램으로 분석하여 grayscale 값으로 정량화 하였다. 이를 통해 3D-μPAD를 제작함으로써 특별한 분석 기기 없이 다양한 중금속 비색 검출을 수행함으로써 조기진단 바이오 센서로의 응용 가능성을 증명하였다. 이 3D-μPAD는 휴대가 간편한 다중 금속이온 검출 바이오센서로서, 신속한 현장 모니터링이 가능하므로 개발도상국 같은 자원이 제한된 지역에서 유용하게 사용 가능하다.

• Bulletin of the Korean Chemical Society
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• 제22권4호
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• pp.405-408
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• 2001

New lipophilic triesters of calix[4]arene and calix[4]quinone are investigated as sodium ion-selective ionophores in poly(vinyl chloride) membrane electrodes. For an ion selective electrode based on calix[4]arene triester I, the linear response is 1 ${\times}$10-3.5 to 1 ${\times}$ 10-1 M of Na+ concentrations. The selectivity coefficients for sodium ion over alkali metal and ammonium ions are determined. The detection limit (logaNa+ = -4.50) and the selectivity coefficient (logKNa+,K+pot = -1.86) are obtained for polymeric membrane electrode containing calix[4]arene triester I.