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Chen CC, Lo SC, Wei PK. Combination of Capped Gold Nanoslit Array and Electrochemistry for Sensitive Aqueous Mercuric Ions Detection. NANOMATERIALS (BASEL, SWITZERLAND) 2021; 12:88. [PMID: 35010038 PMCID: PMC8746490 DOI: 10.3390/nano12010088] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 12/17/2021] [Accepted: 12/24/2021] [Indexed: 06/14/2023]
Abstract
Label-free surface plasmon resonance (SPR) detection of mercuric ions in various aqueous solutions, using capped gold nanoslit arrays combined with electrochemical (EC) sensing technique, is demonstrated. The nanoslit arrays are fabricated on flexible cyclo-olefin polymer substrates by a nanoimprinting lithography method. The EC and SPR signals for the investigation of current responses and transmission SPR spectra are simultaneously measured during metal ions electrodeposition. Glycerol-water solution is studied to evaluate the resonant peak wavelength sensitivity (480.3 nm RIU-1) with a FOM of 40.0 RIU-1 and the obtained intensity sensitivity is 1819.9%. The ferrocyanide/ferricyanide redox couple performs the diffusion controlled electrochemical processes (R2 = 0.99). By investigating the SPR intensity changes and wavelength shifts of various mercuric ion concentrations, the optical properties are evaluated under chronoamperometric conditions. The sensors are evaluated in the detection range between 100 μM and 10 nM with a detection limit of 1 μM. The time dependence of SPR signals and the selectivity of 10 μM Hg2+ in the presence of 10 μM interfering metal ion species from Ca2+, Co2+, Ni2+, Na+, Cu2+, Pb2 + and Mn2+ are determined. The capped gold nanoslit arrays show the selectivity of Hg2+ and the EC sensing method is effectively utilized to aqueous Hg2+ detection. This study provides a label-free detection technique of mercuric ions and this developed system is potentially applicable to detecting chemicals and biomolecules.
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Affiliation(s)
- Cheng-Chuan Chen
- Research Center for Applied Sciences, Academia Sinica, Taipei 11529, Taiwan; (C.-C.C.); (S.-C.L.)
| | - Shu-Cheng Lo
- Research Center for Applied Sciences, Academia Sinica, Taipei 11529, Taiwan; (C.-C.C.); (S.-C.L.)
- Institute of Applied Mechanics, National Taiwan University, Taipei 11529, Taiwan
| | - Pei-Kuen Wei
- Research Center for Applied Sciences, Academia Sinica, Taipei 11529, Taiwan; (C.-C.C.); (S.-C.L.)
- Institute of Biophotonics, National Yang-Ming University, Taipei 11221, Taiwan
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Silalahi HM, Tsai YH, Lee KL, Wei PK, Huang CY. Large shift of resonance wavelengths of silver nanoslit arrays using electrowetting-on-dielectric cells. OPTICS LETTERS 2021; 46:705-708. [PMID: 33577494 DOI: 10.1364/ol.415500] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 01/05/2021] [Indexed: 06/12/2023]
Abstract
A simple design for shifting the resonance wavelength of silver nanoslits using an electrowetting-on-dielectric (EWOD) cell is proposed. The EWOD cell comprises a polycarbonate (PC) substrate with Teflon-coated silver nanoslits and a glass substrate with Teflon-coated electrodes. A glycerol droplet is placed between the two substrates, and out of the path of a probe beam at zero electric field. Application of an electric field smaller than 0.3 V/µm on the electrodes moves the glycerol droplet into the path of the probe beam, shifting the resonance wavelength of the silver nanoslits by 135 nm. A change (0.33) in the refractive index of the effective medium that is adjacent to the silver nanoslits causes a large shift in the resonance wavelength. The spectral shift of the silver nanoslits is repeatable by the electric field. This simple design is a great achievement for high-performance electro-optical devices with large wavelength shift ranges such as optical switches, variable optical attenuators, and sensor applications.
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Librizzi P, Biswas A, Chang R, Kong XT, Moocarme M, Ahuja G, Kretzschmar I, Vuong LT. Broadband chiral hybrid plasmon modes on nanofingernail substrates. NANOSCALE 2020; 12:3827-3833. [PMID: 31995089 DOI: 10.1039/c9nr07394a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
There is significant interest in the utility of asymmetric nanoaperture arrays as substrates for the surface-enhanced detection, fluorescence, and imaging of individual molecules. This work introduces obliquely-cut, out-of-plane, coaxial layered structures on an aperture edge. We refer to these structures as nanofingernails, which emphasizes their curved, oblique, and out-of-plane features. Broadband coupling into chiral hybrid plasmon modes and helicity-dependent near-field scattering without circular dichroism are demonstrated. The unusually-broadband, multipolar modes of nanofingernail micropore structures exhibit phase retardation effects that may be useful for achieving spatial overlap at different frequencies. The nanofingernail geometry shows new potential for simultaneous polarization-enhanced hyperspectral imaging on apertured, plasmonic surfaces.
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Affiliation(s)
- Paulina Librizzi
- Department of Chemical Engineering, City College of New York of the City University of New York (CUNY), New York, New York 10031, USA.
| | - Aneek Biswas
- Department of Physics, Graduate Center of the City University of New York (CUNY), New York, New York 10016, USA. and Department of Physics, Queens College of the City University of New York (CUNY), Queens, New York 11367, USA
| | - Roger Chang
- Department of Chemical Engineering, City College of New York of the City University of New York (CUNY), New York, New York 10031, USA.
| | - Xiang-Tian Kong
- Department of Mechanical Engineering, Bourns Hall, University of California at Riverside, Riverside, California 92521, USA
| | - Matthew Moocarme
- Department of Physics, Graduate Center of the City University of New York (CUNY), New York, New York 10016, USA. and Department of Physics, Queens College of the City University of New York (CUNY), Queens, New York 11367, USA
| | - Gaurav Ahuja
- Department of Mechanical Engineering, Bourns Hall, University of California at Riverside, Riverside, California 92521, USA
| | - Ilona Kretzschmar
- Department of Chemical Engineering, City College of New York of the City University of New York (CUNY), New York, New York 10031, USA.
| | - Luat T Vuong
- Department of Physics, Graduate Center of the City University of New York (CUNY), New York, New York 10016, USA. and Department of Physics, Queens College of the City University of New York (CUNY), Queens, New York 11367, USA and Department of Mechanical Engineering, Bourns Hall, University of California at Riverside, Riverside, California 92521, USA
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Low-Cost and Rapid Fabrication of Metallic Nanostructures for Sensitive Biosensors Using Hot-Embossing and Dielectric-Heating Nanoimprint Methods. SENSORS 2017; 17:s17071548. [PMID: 28671600 PMCID: PMC5539740 DOI: 10.3390/s17071548] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 06/26/2017] [Accepted: 06/29/2017] [Indexed: 01/05/2023]
Abstract
We propose two approaches—hot-embossing and dielectric-heating nanoimprinting methods—for low-cost and rapid fabrication of periodic nanostructures. Each nanofabrication process for the imprinted plastic nanostructures is completed within several seconds without the use of release agents and epoxy. Low-cost, large-area, and highly sensitive aluminum nanostructures on A4 size plastic films are fabricated by evaporating aluminum film on hot-embossing nanostructures. The narrowest bandwidth of the Fano resonance is only 2.7 nm in the visible light region. The periodic aluminum nanostructure achieves a figure of merit of 150, and an intensity sensitivity of 29,345%/RIU (refractive index unit). The rapid fabrication is also achieved by using radio-frequency (RF) sensitive plastic films and a commercial RF welding machine. The dielectric-heating, using RF power, takes advantage of the rapid heating/cooling process and lower electric power consumption. The fabricated capped aluminum nanoslit array has a 5 nm Fano linewidth and 490.46 nm/RIU wavelength sensitivity. The biosensing capabilities of the metallic nanostructures are further verified by measuring antigen–antibody interactions using bovine serum albumin (BSA) and anti-BSA. These rapid and high-throughput fabrication methods can benefit low-cost, highly sensitive biosensors and other sensing applications.
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Lee KL, Chang CC, You ML, Pan MY, Wei PK. Enhancing the Surface Sensitivity of Metallic Nanostructures Using Oblique-Angle-Induced Fano Resonances. Sci Rep 2016; 6:33126. [PMID: 27609431 PMCID: PMC5016831 DOI: 10.1038/srep33126] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 08/22/2016] [Indexed: 11/18/2022] Open
Abstract
Surface sensitivity is an important factor that determines the minimum amount of biomolecules detected by surface plasmon resonance (SPR) sensors. We propose the use of oblique-angle-induced Fano resonances caused by two-mode coupling or three-mode coupling between the localized SPR mode and long-range surface plasmon polariton modes to increase the surface sensitivities of silver capped nanoslits. The results indicate that the coupled resonance between the split SPR (−kSPR) and cavity modes (two-mode coupling) has a high wavelength sensitivity for small-angle incidence (2°) due to its short decay length. Additionally, three-mode coupling between the split SPR (−kSPR), substrate (+kSub) and cavity modes has a high intensity sensitivity for large-angle incidence due to its short decay length, large resonance slope and enhanced transmission intensity. Compared to the wavelength measurement, the intensity measurement has a lower detectable (surface) concentration below 1 ng/ml (0.14 pg/mm2) and is reduced by at least 3 orders of magnitude. In addition, based on the calibration curve and current system noise, a theoretical detection limit of 2.73 pg/ml (0.38 fg/mm2) can be achieved. Such a surface concentration is close to that of prism-based SPR with phase measurement (0.1–0.2 fg/mm2 under a phase shift of 5 mdeg).
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Affiliation(s)
- Kuang-Li Lee
- Research Center for Applied Sciences, Academia Sinica, 128, section 2, Academia Road, Nangkang, Taipei 11529, Taiwan
| | - Chia-Chun Chang
- Department of Optoelectronics, National Taiwan Ocean University, Keelung 20224, Taiwan
| | - Meng-Lin You
- Research Center for Applied Sciences, Academia Sinica, 128, section 2, Academia Road, Nangkang, Taipei 11529, Taiwan
| | - Ming-Yang Pan
- Research Center for Applied Sciences, Academia Sinica, 128, section 2, Academia Road, Nangkang, Taipei 11529, Taiwan.,Institute of Photonics Technologies, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Pei-Kuen Wei
- Research Center for Applied Sciences, Academia Sinica, 128, section 2, Academia Road, Nangkang, Taipei 11529, Taiwan.,Department of Optoelectronics, National Taiwan Ocean University, Keelung 20224, Taiwan.,Institute of Biophotonics, National Yang-Ming University, Taipei, Taiwan
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Wu F, Liu L, Feng L, Xu D, Lu N. Improving the sensing performance of double gold gratings by oblique incident light. NANOSCALE 2015; 7:13026-13032. [PMID: 26172223 DOI: 10.1039/c5nr02660a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Here we demonstrate a simple method to improve the plasmonic sensing performance of gold gratings. The gratings consist of periodic polymer gratings covered with a gold layer, created by nanoimprint lithography and metal deposition. We investigated the effect of gold thickness and the incident angles on the plasmonic sensing performance. With the optimized gold layer, the full-width at half maximum of this grating was reduced by 60% by using the oblique incident light instead of the normal incident light. A maximum value of the figure of merit at oblique incidence is 12, which is double the one at normal incidence.
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Affiliation(s)
- Feifei Wu
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, P. R. China.
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Lin EH, Tsai WS, Lee KL, Lee MCM, Wei PK. Enhancing detection sensitivity of metallic nanostructures by resonant coupling mode and spectral integration analysis. OPTICS EXPRESS 2014; 22:19621-19632. [PMID: 25321045 DOI: 10.1364/oe.22.019621] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We report a simple method to efficiently improve the detection limit of surface plasmon resonance in periodic metallic nanostructures by using small angle illumination and spectral integration analysis. The large-area gold nanoslit arrays were fabricated by thermal-annealing template-stripping method with a slit width of 60 nm and period of 500 nm. The small angle illumination induced a resonant coupling between surface plasmon mode and substrate mode. It increased ~2.24 times intensity sensitivity at 5.5° incident angle. The small-angle illumination also resulted in multiple resonant peaks. The spectral integration method integrated all changes near the resonant peaks and increased the signal to noise ratio about 5 times as compared to single-wavelength intensity analysis. Combining both small angle and spectral integration, the detection limit was increased to one order of magnitude. The improvement of the detection limit for antigen-antibody interactions was demonstrated.
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