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Grogan C, Amarandei G, Lawless S, Pedreschi F, Lyng F, Benito-Lopez F, Raiteri R, Florea L. Silicon Microcantilever Sensors to Detect the Reversible Conformational Change of a Molecular Switch, Spiropyan. SENSORS (BASEL, SWITZERLAND) 2020; 20:E854. [PMID: 32041095 PMCID: PMC7039217 DOI: 10.3390/s20030854] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 01/22/2020] [Accepted: 01/31/2020] [Indexed: 12/13/2022]
Abstract
The high sensitivity of silicon microcantilever sensors has expanded their use in areas ranging from gas sensing to bio-medical applications. Photochromic molecules also represent promising candidates for a large variety of sensing applications. In this work, the operating principles of these two sensing methods are combined in order to detect the reversible conformational change of a molecular switch, spiropyran. Thus, arrays of silicon microcantilever sensors were functionalized with spiropyran on the gold covered side and used as test microcantilevers. The microcantilever deflection response was observed, in five sequential cycles, as the transition from the spiropyran (SP) (CLOSED) to the merocyanine (MC) (OPEN) state and vice-versa when induced by UV and white light LED sources, respectively, proving the reversibility capabilities of this type of sensor. The microcantilever deflection direction was observed to be in one direction when changing to the MC state and in the opposite direction when changing back to the SP state. A tensile stress was induced in the microcantilever when the SP to MC transition took place, while a compressive stress was observed for the reverse transition. These different type of stresses are believed to be related to the spatial conformational changes induced in the photochromic molecule upon photo-isomerisation.
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Affiliation(s)
- Catherine Grogan
- School of Physics & Clinical & Optometric Sciences, Technological University of Dublin, Kevin Street, D08NF82 Dublin, Ireland; (C.G.); (G.A.); (F.P.); (F.L.)
| | - George Amarandei
- School of Physics & Clinical & Optometric Sciences, Technological University of Dublin, Kevin Street, D08NF82 Dublin, Ireland; (C.G.); (G.A.); (F.P.); (F.L.)
| | - Shauna Lawless
- Insight Centre for Data Analytics, National Centre for Sensor Research, Dublin City University, 9 Dublin, Ireland;
| | - Fran Pedreschi
- School of Physics & Clinical & Optometric Sciences, Technological University of Dublin, Kevin Street, D08NF82 Dublin, Ireland; (C.G.); (G.A.); (F.P.); (F.L.)
| | - Fiona Lyng
- School of Physics & Clinical & Optometric Sciences, Technological University of Dublin, Kevin Street, D08NF82 Dublin, Ireland; (C.G.); (G.A.); (F.P.); (F.L.)
- FOCAS Institute, Technological University Dublin, Camden Row, 8 Dublin, Ireland
| | - Fernando Benito-Lopez
- Analytical Microsystems & Materials for Lab-on-a-Chip Group (AMMa-LOAC), Microfluidics Cluster UPV/EHU, Analytical Chemistry Department, University of the Basque Country UPV/EHU, 01006 Vitoria-Gasteiz, Spain;
| | - Roberto Raiteri
- Department of Informatics, Bioengineering, Robotics and System Engineering, University of Genova, 16145 Genova, Italy;
| | - Larisa Florea
- School of Chemistry & AMBER, the SFI Research Centre for Advanced Materials and BioEngineering Research, Trinity College Dublin, the University of Dublin, College Green, 2 Dublin, Ireland
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Steffens C, Brezolin AN, Steffens J. Conducting Polymer-Based Cantilever Sensors for Detection Humidity. SCANNING 2018; 2018:4782685. [PMID: 29967658 PMCID: PMC6008807 DOI: 10.1155/2018/4782685] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Revised: 03/12/2018] [Accepted: 04/29/2018] [Indexed: 06/08/2023]
Abstract
This paper describes the use of different conducting polymers (polyaniline, poly(o-ethoxyaniline), and polypyrrole) as a sensitive layer on a silicon cantilever sensor. The mechanical response (deflection) of the bimaterial (the coated cantilever) was investigated under the influence of relative humidity. The variations in the deflection of the coated cantilevers when exposed to relative humidity were evaluated. The results indicated a linear sensitivity in ranges, where the high value was obtained for a polypyrrole-sensitive layer between 20 and 45% of humidity. Furthermore, the sensor shows excellent performance along with rapid response and recovery times, relatively low hysteresis, and excellent stability. The sensors developed are potentially excellent materials for sensing low humidity for long time.
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Affiliation(s)
- Clarice Steffens
- Department of Food Engineering, URI, Campus of Erechim, Av. Sete de Setembro 1621, 99709-910 Erechim, RS, Brazil
| | - Alexandra Nava Brezolin
- Department of Food Engineering, URI, Campus of Erechim, Av. Sete de Setembro 1621, 99709-910 Erechim, RS, Brazil
| | - Juliana Steffens
- Department of Food Engineering, URI, Campus of Erechim, Av. Sete de Setembro 1621, 99709-910 Erechim, RS, Brazil
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Steffens C, Leite FL, Manzoli A, Sandoval RD, Fatibello O, Herrmann PSP. Microcantilever sensors coated with doped polyaniline for the detection of water vapor. SCANNING 2014; 36:311-316. [PMID: 23817929 DOI: 10.1002/sca.21109] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Accepted: 05/31/2013] [Indexed: 06/02/2023]
Abstract
In the present work, PANI (polyaniline) emeraldine salt (doped) and base (dedoped) were used as the sensitive layer of a silicon microcantilever, and the mechanical response (deflection) of the bimaterial (coated microcantilever) was investigated under the influence of humidity. PANI in the emeraldine base oxidation state was obtained by interfacial synthesis and was deposited on the microcantilever surface by spin-coating (dedoped). Next, the conducting polymer was doped with 1 M HCl (hydrochloric acid). A four-quadrant AFM head with an integrated laser and a position-sensitive detector (AFM Veeco Dimension V) was used to measure the optical deflection of the coated microcantilever. The deflection of the coated (doped and undoped PANI) and uncoated microcantilever was measured under different humidities (in triplicate) at room pressure and temperature in a closed chamber to evaluate the sensor's sensitivity. The relative humidity (RH) in the chamber was varied from 20% to 70% using dry nitrogen as a carrier gas, which was passed through a bubbler containing water to generate humidity. The results showed that microcantilevers coated with sensitive layers of doped and undoped PANI films were sensitive (12,717 ± 6% and 6,939 ± 8%, respectively) and provided good repeatability (98.6 ± 0.015% and 99 ± 0.01%, respectively) after several cycles of exposure to RH. The microcantilever sensor without a PANI coating (uncoated) was not sensitive to humidity. The strong effect of doping on the sensitivity of the sensor was attributed to an increased adsorption of water molecules dissociated at imine nitrogen centers, which improves the performance of the coated microcantilever sensor. Moreover, microcantilever sensors coated with a sensitive layer provided good results in several cycles of exposure to RH (%).
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Affiliation(s)
- C Steffens
- Department of Biotechnology, Federal University de São Carlos (UFSCar), SP, Brazil; National Nanotechnology Laboratory for Agribusiness, Embrapa Instrumentation, São Carlos, SP, Brazil
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Anderson RR, Hu W, Noh JW, Dahlquist WC, Ness SJ, Gustafson TM, Richards DC, Kim S, Mazzeo BA, Woolley AT, Nordin GP. Transient deflection response in microcantilever array integrated with polydimethylsiloxane (PDMS) microfluidics. LAB ON A CHIP 2011; 11:2088-96. [PMID: 21547316 DOI: 10.1039/c1lc20025a] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
We report the integration of a nanomechanical sensor consisting of 16 silicon microcantilevers with polydimethylsiloxane (PDMS) microfluidics. For microcantilevers positioned near the bottom of a microfluidic flow channel, a transient differential analyte concentration for the top versus bottom surface of each microcantilever is created when an analyte-bearing fluid is introduced into the flow channel (which is initially filled with a non-analyte containing solution). We use this effect to characterize a bare (nonfunctionalized) microcantilever array in which the microcantilevers are simultaneously read out with our recently developed high sensitivity in-plane photonic transduction method. We first examine the case of non-specific binding of bovine serum albumin (BSA) to silicon. The average maximum transient microcantilever deflection in the array is -1.6 nm, which corresponds to a differential surface stress of only -0.23 mN m(-1). This is in excellent agreement with the maximum differential surface stress calculated based on a modified rate equation in conjunction with finite element simulation. Following BSA adsorption, buffer solutions with different pH are introduced to further study microcantilever array transient response. Deflections of 20-100 nm are observed (2-14 mN m(-1) differential surface stress). At a flow rate of 5 μL min(-1), the average measured temporal width (FWHM) of the transient response is 5.3 s for BSA non-specific binding and 0.74 s for pH changes.
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Affiliation(s)
- Ryan R Anderson
- Department of Electrical and Computer Engineering, Brigham Young University, Provo, UT 84602, USA
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Tark SH, Das A, Sligar S, Dravid VP. Nanomechanical detection of cholera toxin using microcantilevers functionalized with ganglioside nanodiscs. NANOTECHNOLOGY 2010; 21:435502. [PMID: 20890017 PMCID: PMC3868204 DOI: 10.1088/0957-4484/21/43/435502] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The label-free detection of cholera toxin is demonstrated using microcantilevers functionalized with ganglioside nanodiscs. The cholera toxin molecules bind specifically to the active membrane protein encased in nanodiscs, nanoscale lipid bilayers surrounded by an amphipathic protein belt, immobilized on the cantilever surface. The specific molecular binding results in cantilever deflection via the formation of a surface stress-induced bending moment. The nanomechanical cantilever response is quantitatively monitored by optical interference. The consistent and reproducible nanomechanical detection of cholera toxin in nanomolar range concentrations is demonstrated. The results validated with such a model system suggest that the combination of a microcantilever platform with receptor nanodiscs is a promising approach for monitoring invasive pathogens and other types of biomolecular detection relevant to drug discovery.
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Affiliation(s)
- Soo-Hyun Tark
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Aditi Das
- Department of Biochemistry and Chemistry, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Stephen Sligar
- Department of Biochemistry and Chemistry, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Vinayak P. Dravid
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA
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Hu W, Anderson R, Qian Y, Song J, Noh JW, Kim S, Nordin GP. Demonstration of microcantilever array with simultaneous readout using an in-plane photonic transduction method. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2009; 80:085101. [PMID: 19725675 DOI: 10.1063/1.3186735] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We demonstrate a microcantilever array with an in-plane photonic transduction method for simultaneous readout of each microcantilever. The array is fabricated on a silicon-on-insulator substrate. Rib waveguides in conjunction with a compact waveguide splitter network comprised of trench-based splitters and trench-based bends route light from a single optical input to each microcantilever on the chip. Light propagates down a rib waveguide integrated into the microcantilever and, at the free end of the microcantilever, crosses a small gap. Light is captured in static asymmetric multimode waveguides that terminate in Y-branches, the outputs of which are imaged onto an InGaAs line scan camera. A differential signal for each microcantilever is simultaneously formed from the two outputs of the corresponding Y-branch. We demonstrate that reasonable signal uniformity is obtained with a scaled differential signal for seven out of nine surviving microcantilevers in an array.
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Affiliation(s)
- Weisheng Hu
- Electrical and Computer Engineering, Brigham Young University, Provo, Utah 84602, USA
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Liu Y, Yang J. Coupling effects of refractive index discontinuity, spot size and spot location on the deflection sensitivity of optical-lever based atomic force microscopy. NANOTECHNOLOGY 2008; 19:235501. [PMID: 21825794 DOI: 10.1088/0957-4484/19/23/235501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Atomic force microscopy (AFM) plays an essential role in nanotechnology and nanoscience. The recent advances of AFM in bionanotechnology include phase imaging of living cells and detection of biomolecular interactions in liquid biological environments. Deflection sensitivity is a key factor in both imaging and force measurement, which is significantly affected by the coupling effects of the refractive index discontinuity between air, the glass window and the liquid medium, and the laser spot size and spot location. The effects of both the spot size and the spot location on the sensitivity are amplified by the refractive index discontinuity. The coupling effects may govern a transition of the deflection sensitivity from enhancement to degradation. It is also found that there is a critical value for the laser spot size, above which the deflection sensitivity is mainly determined by the refractive index of the liquid. Experimental results, in agreement with theoretical predication, elucidate the coupling effects.
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Affiliation(s)
- Yu Liu
- Department of Mechanical and Materials Engineering, University of Western Ontario, Canada
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