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Moore D, Arcila JA, Saraf RF. Electrochemical Deposition of Polyelectrolytes Is Maximum at the Potential of Zero Charge. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:1864-1870. [PMID: 32073857 DOI: 10.1021/acs.langmuir.9b03734] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Electrochemical deposition of cationic and anionic polyelectrolyte on a Au electrode is studied as a function of applied potential between the electrode and the solution of monovalent electrolyte. The deposition is measured by open circuit potential relative to a pristine electrode in a reference solution (100 mM NaCl). The rate of deposition is measured by a home-built electrochemical-optical method in real time. It was discovered that the polarity of the potential and magnitude of the potential are not the primary reasons to enhance deposition. For example, both the amount and rate of deposition of negatively charged poly(styrenesulfonate) in NaCl are higher when the electrode is at -200 mV than at +200 mV with respect to the solution. The results are explained in terms of the charge state of the electrical double layer that is primarily controlled by supporting (small) ions.
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Tevatia R, Prasad A, Saraf RF. Electrochemical Characteristics of a DNA Modified Electrode as a Function of Percent Binding. Anal Chem 2019; 91:10501-10508. [PMID: 31313582 DOI: 10.1021/acs.analchem.9b01416] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Electrochemical characteristics of immobilized double-stranded DNA (dsDNA) on a Au electrode were studied as a function of coverage using a home-built optoelectrochemical method. The method allows probing of local redox processes on a 6 μm spot by measuring both differential reflectivity (SEED-R) and interferometry (SEED-I). The former is sensitive to redox ions that tend to adsorb to the electrode, while SEED-I is sensitive to nonadsorbing ions. The redox reaction maxima, Rmax and Δmax from SEED-R and SEED-I, respectively, are linearly proportional to amperometric peak current, Imax. The DNA binding is measured by a redox active dye, methylene blue, that intercalates in dsDNA, leading to an Rmax. Concomitantly, the absence of Δmax for [Fe(CN)6]4-/3- by SEED-I ensures that there is no leakage current from voids/defects in the alkanethiol passivation layer at the same spot of measurement. The binding was regulated electrochemically to obtain the binding fraction, f, ranging about three orders of magnitude. A remarkably sharp transition, f = fT = 1.25 × 10-3, was observed. Below fT, dsDNA molecules behaved as individual single-molecule nanoelectrodes. Above the crossover transition, Rmax, per dsDNA molecule dropped rapidly as f-1/2 toward a planar-like monolayer. The SEED-R peak at f ∼ 3.3 × 10-4 (∼270 dsDNA molecules) was (statistically) robust, corresponding to a responsivity of ∼0.45 zeptomoles of dsDNA/spot. Differential pulse voltammetry in the single-molecule regime estimated that the current per dsDNA molecule was ∼4.1 fA. Compared with published amperometric results, the reported semilogarithmic dependence on target concentration is in the f > fT regime.
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Affiliation(s)
- Rahul Tevatia
- Vajra Instruments, Inc , Lincoln , Nebraska 68512 , United States
| | - Abhijeet Prasad
- Department of Chemical and Biomolecular Engineering , University of Nebraska , Lincoln , Nebraska 68512 , United States
| | - Ravi F Saraf
- Department of Chemical and Biomolecular Engineering , University of Nebraska , Lincoln , Nebraska 68512 , United States.,Nebraska Center for Materials and Nanoscience , University of Nebraska , Lincoln , Nebraska 68512 , United States
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Moore D, Saraf RF. Simultaneous Printing of Two Inks by Contact Lithography. ACS APPLIED MATERIALS & INTERFACES 2018; 10:14193-14199. [PMID: 29617566 DOI: 10.1021/acsami.8b03038] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Microcontact printing (μCP) is a valuable technique used to fabricate complex patterns on surfaces for applications such as sensors, cell seeding, self-assembled monolayers of proteins and nanoparticles, and micromachining. The process is very precise but is typically confined to depositing a single type of ink per print, which limits the complexity of using multifunctionality patterns. Here we describe a process by which two inks are printed concomitantly in a single operation to create an alternating pattern of hydrophobic and hydrophilic characteristics. The hydrophobic ink, PDMS, is deposited by evaporation on the noncontact region, while the hydrophilic polyelectrolyte is transferred on contact. We demonstrate that there is no gap between the two patterns using an optical-electrochemical method. We describe some potential applications of this method, including layer-by-layer deposition of polyelectrolytes for sensors and creation of a scaffold for cell culture.
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Affiliation(s)
- David Moore
- Department of Chemical and Biomolecular Engineering , University of Nebraska-Lincoln , Lincoln , Nebraska 68588 , United States
| | - Ravi F Saraf
- Department of Chemical and Biomolecular Engineering , University of Nebraska-Lincoln , Lincoln , Nebraska 68588 , United States
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Raghunath S, Prasad A, Tevatia R, Gunther JR, Roy S, Krishnan S, Saraf RF. Quantitative Electrochemical DNA Microarray on a Monolith Electrode with Ten Attomolar Sensitivity, 100% Specificity, and Zero Background. ChemElectroChem 2018; 5:429-433. [PMID: 31157159 PMCID: PMC6541448 DOI: 10.1002/celc.201700983] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Indexed: 01/01/2023]
Abstract
Circulating microRNA are promising diagnostic and prognostic biomarkers of disease in quantitative blood tests. A label-free, PCR-free, electrochemical microarray technology on a monolith electrode is described, with 10 attomolar (aM) sensitivity and responsiveness to binding of <1 zeptomole of target to immobilized ssDNA probes with zero background. Specificity is 100% in a mixture with five nonspecific miRNA each with a 103-fold higher concentration. Direct measurement on plasma-derived miRNA without cDNA conversion and PCR demonstrated multiplexing and near-ideal quantitative correlation with an equivalent pure sample. The dynamic range is a target concentration ranging from 10-2 to 103 femtomolar (fM). This PCR-free novel technology can be applied as a test for cancer diagnosis/prognosis to detect 103 copies of a miRNA sequence in RNA extracted from 100 μL of plasma.
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Affiliation(s)
| | - Abhijeet Prasad
- Vajra Instruments, Inc.Lincoln, NE 68512 USA
- Chemical Engineering, University of Nebraska Lincoln, NE 68588 USA
| | - Rahul Tevatia
- Chemical Engineering, University of Nebraska Lincoln, NE 68588 USA
| | | | - Santanu Roy
- Vajra Instruments, Inc.Lincoln, NE 68512 USA
| | - Sunil Krishnan
- MD Anderson Cancer Research Center Houston, TX 77030 USA
| | - Ravi F Saraf
- Chemical Engineering, University of Nebraska Lincoln, NE 68588 USA
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Heavy metal ion detection on a microspot electrode using an optical electrochemical probe. Electrochem commun 2018. [DOI: 10.1016/j.elecom.2017.11.021] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Ribeiro JA, Fernandes PM, Pereira CM, Silva F. Electrochemical sensors and biosensors for determination of catecholamine neurotransmitters: A review. Talanta 2016; 160:653-679. [DOI: 10.1016/j.talanta.2016.06.066] [Citation(s) in RCA: 102] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Revised: 06/28/2016] [Accepted: 06/30/2016] [Indexed: 01/03/2023]
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Byeon HH, Lee SW, Lee EH, Kim W, Yi H. Biologically templated assembly of hybrid semiconducting nanomesh for high performance field effect transistors and sensors. Sci Rep 2016; 6:35591. [PMID: 27762315 PMCID: PMC5071876 DOI: 10.1038/srep35591] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 10/03/2016] [Indexed: 01/05/2023] Open
Abstract
Delicately assembled composites of semiconducting nanomaterials and biological materials provide an attractive interface for emerging applications, such as chemical/biological sensors, wearable health monitoring devices, and therapeutic agent releasing devices. The nanostructure of composites as a channel and a sensing material plays a critical role in the performance of field effect transistors (FETs). Therefore, it is highly desirable to prepare elaborate composite that can allow the fabrication of high performance FETs and also provide high sensitivity and selectivity in detecting specific chemical/biological targets. In this work, we demonstrate that high performance FETs can be fabricated with a hydrodynamically assembled composite, a semiconducting nanomesh, of semiconducting single-walled carbon nanotubes (S-SWNTs) and a genetically engineered M13 phage to show strong binding affinity toward SWNTs. The semiconducting nanomesh enables a high on/off ratio (~104) of FETs. We also show that the threshold voltage and the channel current of the nanomesh FETs are sensitive to the change of the M13 phage surface charge. This biological gate effect of the phage enables the detection of biologically important molecules such as dopamine and bisphenol A using nanomesh-based FETs. Our results provide a new insight for the preparation of composite material platform for highly controllable bio/electronics interfaces.
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Affiliation(s)
- Hye-Hyeon Byeon
- Post-Silicon Semiconductor Institute, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea.,Department of Nano Semiconductor Engineering, Korea University, Seoul, 02841, Republic of Korea
| | - Seung-Woo Lee
- Post-Silicon Semiconductor Institute, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea
| | - Eun-Hee Lee
- Department of Environmental Science and Engineering, Ewha Womans University, Seoul, 03760, Republic of Korea
| | - Woong Kim
- Department of Materials Science and Engineering, Korea University, Seoul, 02841, Republic of Korea
| | - Hyunjung Yi
- Post-Silicon Semiconductor Institute, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea
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Lee SW, Lee KY, Song YW, Choi WK, Chang J, Yi H. Direct Electron Transfer of Enzymes in a Biologically Assembled Conductive Nanomesh Enzyme Platform. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2016; 28:1577-84. [PMID: 26662628 DOI: 10.1002/adma.201503930] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Revised: 10/14/2015] [Indexed: 05/20/2023]
Abstract
Nondestructive assembly of a nanostructured enzyme platform is developed in combination of the specific biomolecular attraction and electrostatic coupling for highly efficient direct electron transfer (DET) of enzymes with unprecedented applicability and versatility. The biologically assembled conductive nanomesh enzyme platform enables DET-based flexible integrated biosensors and DET of eight different enzyme with various catalytic activities.
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Affiliation(s)
- Seung-Woo Lee
- Post-Silicon Semiconductor Institute, Korea Institute of Science and Technology, Seoul, 136-791, Republic of Korea
| | - Ki-Young Lee
- Post-Silicon Semiconductor Institute, Korea Institute of Science and Technology, Seoul, 136-791, Republic of Korea
| | - Yong-Won Song
- Post-Silicon Semiconductor Institute, Korea Institute of Science and Technology, Seoul, 136-791, Republic of Korea
| | - Won Kook Choi
- Materials and Life Science Research Division, Korea Institute of Science and Technology, Seoul, 136-791, Republic of Korea
| | - Joonyeon Chang
- Post-Silicon Semiconductor Institute, Korea Institute of Science and Technology, Seoul, 136-791, Republic of Korea
| | - Hyunjung Yi
- Post-Silicon Semiconductor Institute, Korea Institute of Science and Technology, Seoul, 136-791, Republic of Korea
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