1
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Ferreira LF, Giordano GF, Gobbi AL, Piazzetta MHO, Schleder GR, Lima RS. Real-Time and In Situ Monitoring of the Synthesis of Silica Nanoparticles. ACS Sens 2022; 7:1045-1057. [PMID: 35417147 DOI: 10.1021/acssensors.1c02697] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The real-time and in situ monitoring of the synthesis of nanomaterials (NMs) remains a challenging task, which is of pivotal importance by assisting fundamental studies (e.g., synthesis kinetics and colloidal phenomena) and providing optimized quality control. In fact, the lack of reproducibility in the synthesis of NMs is a bottleneck against the translation of nanotechnologies into the market toward daily practice. Here, we address an impedimetric millifluidic sensor with data processing by machine learning (ML) as a sensing platform to monitor silica nanoparticles (SiO2NPs) over a 24 h synthesis from a single measurement. The SiO2NPs were selected as a model NM because of their extensive applications. Impressively, simple ML-fitted descriptors were capable of overcoming interferences derived from SiO2NP adsorption over the signals of polarizable Au interdigitate electrodes to assure the determination of the size and concentration of nanoparticles over synthesis while meeting the trade-off between accuracy and speed/simplicity of computation. The root-mean-square errors were calculated as ∼2.0 nm (size) and 2.6 × 1010 nanoparticles mL-1 (concentration). Further, the robustness of the ML size descriptor was successfully challenged in data obtained along independent syntheses using different devices, with the global average accuracy being 103.7 ± 1.9%. Our work advances the developments required to transform a closed flow system basically encompassing the reactional flask and an impedimetric sensor into a scalable and user-friendly platform to assess the in situ synthesis of SiO2NPs. Since the sensor presents a universal response principle, the method is expected to enable the monitoring of other NMs. Such a platform may help to pave the way for translating "sense-act" systems into practice use in nanotechnology.
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Affiliation(s)
- Larissa F. Ferreira
- Brazilian Nanotechnology National Laboratory, Brazilian Center for Research in Energy and Materials, Campinas, São Paulo 13083-970, Brazil
- Institute of Chemistry, University of Campinas, Campinas, São Paulo 13083-970, Brazil
| | - Gabriela F. Giordano
- Brazilian Nanotechnology National Laboratory, Brazilian Center for Research in Energy and Materials, Campinas, São Paulo 13083-970, Brazil
| | - Angelo L. Gobbi
- Brazilian Nanotechnology National Laboratory, Brazilian Center for Research in Energy and Materials, Campinas, São Paulo 13083-970, Brazil
| | - Maria H. O. Piazzetta
- Brazilian Nanotechnology National Laboratory, Brazilian Center for Research in Energy and Materials, Campinas, São Paulo 13083-970, Brazil
| | - Gabriel R. Schleder
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Renato S. Lima
- Brazilian Nanotechnology National Laboratory, Brazilian Center for Research in Energy and Materials, Campinas, São Paulo 13083-970, Brazil
- Institute of Chemistry, University of Campinas, Campinas, São Paulo 13083-970, Brazil
- Center for Natural and Human Sciences, Federal University of ABC, Santo André, São Paulo 09210-580, Brazil
- São Carlos Institute of Chemistry, University of São Paulo, São Carlos, São Paulo 13566-590, Brazil
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2
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Liang Y, Hu S, Zhang Q, Zhang D, Guo G, Wang X. Determination of Nanoplastics Using a Novel Contactless Conductivity Detector with Controllable Geometric Parameters. Anal Chem 2022; 94:1552-1558. [DOI: 10.1021/acs.analchem.1c02752] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yingqi Liang
- Center of Excellence for Environmental Safety and Biological Effects, Beijing Key Laboratory for Green Catalysis and Separation, Department of Chemistry and Biology, Beijing University of Technology, Beijing 100124, China
| | - Siqi Hu
- Center of Excellence for Environmental Safety and Biological Effects, Beijing Key Laboratory for Green Catalysis and Separation, Department of Chemistry and Biology, Beijing University of Technology, Beijing 100124, China
| | - Qi Zhang
- Center of Excellence for Environmental Safety and Biological Effects, Beijing Key Laboratory for Green Catalysis and Separation, Department of Chemistry and Biology, Beijing University of Technology, Beijing 100124, China
| | - Dongtang Zhang
- Center of Excellence for Environmental Safety and Biological Effects, Beijing Key Laboratory for Green Catalysis and Separation, Department of Chemistry and Biology, Beijing University of Technology, Beijing 100124, China
| | - Guangsheng Guo
- Center of Excellence for Environmental Safety and Biological Effects, Beijing Key Laboratory for Green Catalysis and Separation, Department of Chemistry and Biology, Beijing University of Technology, Beijing 100124, China
| | - Xiayan Wang
- Center of Excellence for Environmental Safety and Biological Effects, Beijing Key Laboratory for Green Catalysis and Separation, Department of Chemistry and Biology, Beijing University of Technology, Beijing 100124, China
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3
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Neckel IT, de Castro LF, Callefo F, Teixeira VC, Gobbi AL, Piazzetta MH, de Oliveira RAG, Lima RS, Vicente RA, Galante D, Tolentino HCN. Development of a sticker sealed microfluidic device for in situ analytical measurements using synchrotron radiation. Sci Rep 2021; 11:23671. [PMID: 34880305 PMCID: PMC8654830 DOI: 10.1038/s41598-021-02928-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Accepted: 11/22/2021] [Indexed: 01/09/2023] Open
Abstract
Shedding synchrotron light on microfluidic systems, exploring several contrasts in situ/operando at the nanoscale, like X-ray fluorescence, diffraction, luminescence, and absorption, has the potential to reveal new properties and functionalities of materials across diverse areas, such as green energy, photonics, and nanomedicine. In this work, we present the micro-fabrication and characterization of a multifunctional polyester/glass sealed microfluidic device well-suited to combine with analytical X-ray techniques. The device consists of smooth microchannels patterned on glass, where three gold electrodes are deposited into the channels to serve in situ electrochemistry analysis or standard electrical measurements. It has been efficiently sealed through an ultraviolet-sensitive sticker-like layer based on a polyester film, and The burst pressure determined by pumping water through the microchannel(up to 0.22 MPa). Overall, the device has demonstrated exquisite chemical resistance to organic solvents, and its efficiency in the presence of biological samples (proteins) is remarkable. The device potentialities, and its high transparency to X-rays, have been demonstrated by taking advantage of the X-ray nanoprobe Carnaúba/Sirius/LNLS, by obtaining 2D X-ray nanofluorescence maps on the microchannel filled with water and after an electrochemical nucleation reaction. To wrap up, the microfluidic device characterized here has the potential to be employed in standard laboratory experiments as well as in in situ and in vivo analytical experiments using a wide electromagnetic window, from infrared to X-rays, which could serve experiments in many branches of science.
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Affiliation(s)
- Itamar T Neckel
- Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, 13083-970, Brazil.
| | - Lucas F de Castro
- Institute of Chemistry, Federal University of Goiás, Campus Samambaia, Goiânia, 74690-900, Brazil
| | - Flavia Callefo
- Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, 13083-970, Brazil
| | - Verônica C Teixeira
- Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, 13083-970, Brazil
| | - Angelo L Gobbi
- Brazilian Nanotechnology National Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, 13083-970, Brazil
| | - Maria H Piazzetta
- Brazilian Nanotechnology National Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, 13083-970, Brazil
| | - Ricardo A G de Oliveira
- Brazilian Nanotechnology National Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, 13083-970, Brazil
| | - Renato S Lima
- Brazilian Nanotechnology National Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, 13083-970, Brazil
| | - Rafael A Vicente
- Institute of Chemistry, University of Campinas, Campinas, SãoPaulo, 13083-970, Brazil
| | - Douglas Galante
- Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, 13083-970, Brazil
| | - Helio C N Tolentino
- Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, 13083-970, Brazil.
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4
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He Y, Huang Q, He Y, Ji H, Zhang T, Wang B, Huang Z. A Low Excitation Working Frequency Capacitively Coupled Contactless Conductivity Detection (C 4D) Sensor for Microfluidic Devices. SENSORS 2021; 21:s21196381. [PMID: 34640701 PMCID: PMC8512373 DOI: 10.3390/s21196381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 09/14/2021] [Accepted: 09/20/2021] [Indexed: 11/16/2022]
Abstract
In this work, a new capacitively coupled contactless conductivity detection (C4D) sensor for microfluidic devices is developed. By introducing an LC circuit, the working frequency of the new C4D sensor can be lowered by the adjustments of the inductor and the capacitance of the LC circuit. The limits of detection (LODs) of the new C4D sensor for conductivity/ion concentration measurement can be improved. Conductivity measurement experiments with KCl solutions were carried out in microfluidic devices (500 µm × 50 µm). The experimental results indicate that the developed C4D sensor can realize the conductivity measurement with low working frequency (less than 50 kHz). The LOD of the C4D sensor for conductivity measurement is estimated to be 2.2 µS/cm. Furthermore, to show the effectiveness of the new C4D sensor for the concentration measurement of other ions (solutions), SO42− and Li+ ion concentration measurement experiments were also carried out at a working frequency of 29.70 kHz. The experimental results show that at low concentrations, the input-output characteristics of the C4D sensor for SO42− and Li+ ion concentration measurement show good linearity with the LODs estimated to be 8.2 µM and 19.0 µM, respectively.
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Affiliation(s)
| | | | | | - Haifeng Ji
- Correspondence: ; Tel.: +86-571-8795-2145
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5
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Takekawa VS, Marques LA, Strubinger E, Segato TP, Bogusz S, Brazaca LC, Carrilho E. Development of low-cost planar electrodes and microfluidic channels for applications in capacitively coupled contactless conductivity detection (C 4 D). Electrophoresis 2021; 42:1560-1569. [PMID: 34080201 DOI: 10.1002/elps.202000351] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 05/27/2021] [Accepted: 05/28/2021] [Indexed: 01/11/2023]
Abstract
Electrochemical techniques are commonly applied to micro total analysis system (μTAS) devices mainly due to its high sensitivity and miniaturization capacity. Among many electrochemical techniques, capacitively coupled contactless conductivity detection (C4 D) stands out for not requiring direct electrode-solution contact, avoiding several problems such as electrolysis, bubble formation, and metal degradation. Furthermore, the instrumentation required for C4 D measurements is compact, low cost, and easy to use, allowing in situ measurements to be performed even by nonspecialized personal. Contrarily, the production of metallic electrodes and microchannels adequate for C4 D measurements commonly requires specialized facilities and workers, increasing the costs of applying these methods. We propose alternatives to batch manufacture metallic electrodes and polymeric microchannels for C4 D analysis using more straightforward equipment and lower-cost materials. Three devices with different dielectric layer compositions and electrode sizes were tested and compared regarding their analytical performance. The constructed platforms have shown a reduction of more than 64% in cost when compared to traditional techniques and displayed good linearity (R2 ≥ 0.994), reproducibility (RSD ≤ 4.07%, n = 3), and limits of detection (≤0.26 mmol/L) when measuring standard NaCl samples. Therefore, the proposed methods were successfully validated and are available for further C4 D applications such as diagnosis of dry-eye syndrome.
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Affiliation(s)
- Victor Sadanory Takekawa
- Instituto de Química de São Carlos, Universidade de São Paulo, São Carlos, São Paulo, Brazil.,Instituto Nacional de Ciência e Tecnologia de Bioanalítica-INCTBio, Campinas, São Paulo, Brazil
| | - Letícia Aparecida Marques
- Instituto de Química de São Carlos, Universidade de São Paulo, São Carlos, São Paulo, Brazil.,Instituto Nacional de Ciência e Tecnologia de Bioanalítica-INCTBio, Campinas, São Paulo, Brazil
| | - Ethan Strubinger
- Instituto de Química de São Carlos, Universidade de São Paulo, São Carlos, São Paulo, Brazil.,Instituto Nacional de Ciência e Tecnologia de Bioanalítica-INCTBio, Campinas, São Paulo, Brazil.,Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC
| | - Thiago Pinotti Segato
- Instituto de Química de São Carlos, Universidade de São Paulo, São Carlos, São Paulo, Brazil.,Instituto Nacional de Ciência e Tecnologia de Bioanalítica-INCTBio, Campinas, São Paulo, Brazil
| | - Stanislau Bogusz
- Instituto de Química de São Carlos, Universidade de São Paulo, São Carlos, São Paulo, Brazil
| | - Laís Canniatti Brazaca
- Instituto de Química de São Carlos, Universidade de São Paulo, São Carlos, São Paulo, Brazil.,Instituto Nacional de Ciência e Tecnologia de Bioanalítica-INCTBio, Campinas, São Paulo, Brazil
| | - Emanuel Carrilho
- Instituto de Química de São Carlos, Universidade de São Paulo, São Carlos, São Paulo, Brazil.,Instituto Nacional de Ciência e Tecnologia de Bioanalítica-INCTBio, Campinas, São Paulo, Brazil
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6
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Morbioli GG, Speller NC, Stockton AM. A practical guide to rapid-prototyping of PDMS-based microfluidic devices: A tutorial. Anal Chim Acta 2020; 1135:150-174. [PMID: 33070852 DOI: 10.1016/j.aca.2020.09.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 08/09/2020] [Accepted: 09/07/2020] [Indexed: 12/30/2022]
Abstract
Micro total analytical systems (μTAS) are attractive to multiple fields that include chemistry, medicine and engineering due to their portability, low power usage, potential for automation, and low sample and reagent consumption, which in turn results in low waste generation. The development of fully-functional μTAS is an iterative process, based on the design, fabrication and testing of multiple prototype microdevices. Typically, microfabrication protocols require a week or more of highly-skilled personnel time in high-maintenance cleanroom facilities, which makes this iterative process cost-prohibitive in many locations worldwide. Rapid-prototyping tools, in conjunction with the use of polydimethylsiloxane (PDMS), enable rapid development of microfluidic structures at lower costs, circumventing these issues in conventional microfabrication techniques. Multiple rapid-prototyping methods to fabricate PDMS-based microfluidic devices have been demonstrated in literature since the advent of soft-lithography in 1998; each method has its unique advantages and drawbacks. Here, we present a tutorial discussing current rapid-prototyping techniques to fabricate PDMS-based microdevices, including soft-lithography, print-and-peel and scaffolding techniques, among other methods, specifically comparing resolution of the features, fabrication processes and associated costs for each technique. We also present thoughts and insights towards each step of the iterative microfabrication process, from design to testing, to improve the development of fully-functional PDMS-based microfluidic devices at faster rates and lower costs.
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Affiliation(s)
| | - Nicholas Colby Speller
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, 30332, USA.
| | - Amanda M Stockton
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, 30332, USA.
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7
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Shiroma LS, Oliveira AF, Lobo-Júnior EO, Coltro WK, Gobbi AL, de La Torre LG, Lima RS. High adhesion strength and hybrid irreversible/reversible full-PDMS microfluidic chips. Anal Chim Acta 2017; 951:116-123. [DOI: 10.1016/j.aca.2016.11.048] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 11/17/2016] [Accepted: 11/18/2016] [Indexed: 10/20/2022]
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8
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Self-regenerating and hybrid irreversible/reversible PDMS microfluidic devices. Sci Rep 2016; 6:26032. [PMID: 27181918 PMCID: PMC4867595 DOI: 10.1038/srep26032] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Accepted: 04/25/2016] [Indexed: 11/08/2022] Open
Abstract
This paper outlines a straightforward, fast, and low-cost method to fabricate polydimethylsiloxane (PDMS) chips. Termed sandwich bonding (SWB), this method requires only a laboratory oven. Initially, SWB relies on the reversible bonding of a coverslip over PDMS channels. The coverslip is smaller than the substrate, leaving a border around the substrate exposed. Subsequently, a liquid composed of PDMS monomers and a curing agent is poured onto the structure. Finally, the cover is cured. We focused on PDMS/glass chips because of their key advantages in microfluidics. Despite its simplicity, this method created high-performance microfluidic channels. Such structures featured self-regeneration after leakages and hybrid irreversible/reversible behavior. The reversible nature was achieved by removing the cover of PDMS with acetone. Thus, the PDMS substrate and glass coverslip could be detached for reuse. These abilities are essential in the stages of research and development. Additionally, SWB avoids the use of surface oxidation, half-cured PDMS as an adhesive, and surface chemical modification. As a consequence, SWB allows surface modifications before the bonding, a long time for alignment, the enclosure of sub-micron channels, and the prototyping of hybrid devices. Here, the technique was successfully applied to bond PDMS to Au and Al.
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9
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Kubáň P, Timerbaev AR. Inorganic analysis using CE: Advanced methodologies to face old challenges. Electrophoresis 2013; 35:225-33. [DOI: 10.1002/elps.201300302] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 08/19/2013] [Accepted: 08/19/2013] [Indexed: 12/28/2022]
Affiliation(s)
- Petr Kubáň
- Department of Bioanalytical Instrumentation; CEITEC - Masaryk University; Brno Czech Republic
| | - Andrei R. Timerbaev
- Vernadsky Institute of Geochemistry and Analytical Chemistry; Russian Academy of Sciences; Moscow Russia
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10
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da Silva ER, Segato TP, Coltro WKT, Lima RS, Carrilho E, Mazo LH. Determination of glyphosate and AMPA on polyester-toner electrophoresis microchip with contactless conductivity detection. Electrophoresis 2013; 34:2107-11. [PMID: 23595638 DOI: 10.1002/elps.201200588] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Revised: 03/10/2013] [Accepted: 03/12/2013] [Indexed: 11/07/2022]
Abstract
This paper reports a method for rapid, simple, direct, and reproducible determination of glyphosate and its major metabolite aminomethylphosphonic acid (AMPA). The platform described herein uses polyester-toner microchips incorporating capacitively coupled contactless conductivity detection and electrophoresis separation of the analytes. The polyester-toner microchip presented 150 μm-wide and 12 μm-deep microchannels, with injection and separation lengths of 10 and 40 mm long, respectively. The best results were obtained with 320 kHz frequency, 4.5 Vpp excitation voltage, 80 mmol/L CHES/Tris buffer at pH 8.8, injection in -1.0 kV for 7 s, and separation in -1.5 kV. RSD values related to the peak areas for glyphosate and AMPA were 1.5 and 3.3% and 10.1 and 8.6% for intra- and interchip assays, respectively. The detection limits were 45.1 and 70.5 μmol/L, respectively, without any attempt of preconcentration of the analytes. Finally, the method was applied to river water samples in which glyphosate and AMPA (1.0 mmol/L each) were added. The recovery results were 87.4 and 83.7% for glyphosate and AMPA, respectively. The recovery percentages and LOD values obtained here were similar to others reported in the literature.
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Affiliation(s)
- Eduardo R da Silva
- Instituto de Química de São Carlos, Universidade de São Paulo, São Carlos, SP, Brazil
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11
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Lima RS, Piazzetta MHO, Gobbi AL, Segato TP, Cabral MF, Machado SAS, Carrilho E. Highly sensitive contactless conductivity microchips based on concentric electrodes for flow analysis. Chem Commun (Camb) 2013; 49:11382-4. [DOI: 10.1039/c3cc45797d] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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12
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Kubáň P, Hauser PC. Contactless conductivity detection for analytical techniques: Developments from 2010 to 2012. Electrophoresis 2012; 34:55-69. [DOI: 10.1002/elps.201200358] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Revised: 08/08/2012] [Accepted: 08/09/2012] [Indexed: 11/08/2022]
Affiliation(s)
- Pavel Kubáň
- Institute of Analytical Chemistry of the Academy of Sciences of the Czech Republic; Brno; Czech Republic
| | - Peter C. Hauser
- Department of Chemistry; University of Basel; Basel; Switzerland
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13
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A polydimethylsiloxane electrophoresis microchip with a thickness controllable insulating layer for capacitatively coupled contactless conductivity detection. Electrochem commun 2012. [DOI: 10.1016/j.elecom.2012.10.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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14
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Mark JJP, Scholz R, Matysik FM. Electrochemical methods in conjunction with capillary and microchip electrophoresis. J Chromatogr A 2012; 1267:45-64. [PMID: 22824222 DOI: 10.1016/j.chroma.2012.07.009] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Revised: 07/01/2012] [Accepted: 07/06/2012] [Indexed: 02/06/2023]
Abstract
Electromigrative techniques such as capillary and microchip electrophoresis (CE and MCE) are inherently associated with various electrochemical phenomena. The electrolytic processes occurring in the buffer reservoirs have to be considered for a proper design of miniaturized electrophoretic systems and a suitable selection of buffer composition. In addition, the control of the electroosmotic flow plays a crucial role for the optimization of CE/MCE separations. Electroanalytical methods have significant importance in the field of detection in conjunction with CE/MCE. At present, amperometric detection and contactless conductivity detection are the predominating electrochemical detection methods for CE/MCE. This paper reviews the most recent trends in the field of electrochemical detection coupled to CE/MCE. The emphasis is on methodical developments and new applications that have been published over the past five years. A rather new way for the implementation of electrochemical methods into CE systems is the concept of electrochemically assisted injection which involves the electrochemical conversions of analytes during the injection step. This approach is particularly attractive in hyphenation to mass spectrometry (MS) as it widens the range of CE-MS applications. An overview of recent developments of electrochemically assisted injection coupled to CE is presented.
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Affiliation(s)
- Jonas J P Mark
- Institute of Analytical Chemistry, Chemo- and Biosensors, University of Regensburg, Regensburg, Germany
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15
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Lima RS, Piazzetta MHO, Gobbi AL, Rodrigues-Filho UP, Nascente PAP, Coltro WKT, Carrilho E. Contactless conductivity biosensor in microchip containing folic acid as bioreceptor. LAB ON A CHIP 2012; 12:1963-1966. [PMID: 22549415 DOI: 10.1039/c2lc40157f] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We report a glass/PDMS-based microfluidic biosensor that integrates contactless conductivity transduction and folic acid, a target for tumor biomarker, as a bioreceptor. The device presents relevant advantages such as direct determination--dismiss the use of redox mediators as in faradaic electrochemical techniques--and the absence of the known drawbacks related to the electrode-solution interface. Characterizations of the functionalization processes and chemical sensor are described in this communication.
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Affiliation(s)
- Renato S Lima
- Instituto de Química de São Carlos, Universidade de São Paulo, São Carlos, SP, Brazil
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16
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Moraes FC, Lima RS, Segato TP, Cesarino I, Cetino JLM, Machado SAS, Gomez F, Carrilho E. Glass/PDMS hybrid microfluidic device integrating vertically aligned SWCNTs to ultrasensitive electrochemical determinations. LAB ON A CHIP 2012; 12:1959-1962. [PMID: 22562183 DOI: 10.1039/c2lc40141j] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
This communication reports a promising platform for rapid, simple, direct, and ultrasensitive determination of serotonin. The method is related to integration of vertically aligned single-walled carbon nanotubes (SWCNTs) in electrochemical microfluidic devices. The required microfabrication protocol is simple and fast. In addition, the nanomaterial influenced remarkably the obtained limit-of-detection (LOD) values. Our system achieved a LOD of 0.2 nmol L(-1) for serotonin, to the best of our knowledge one of the lowest values reported in the literature.
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Affiliation(s)
- Fernando Cruz Moraes
- Instituto de Química de São Carlos, Universidade de São Paulo, São Carlos, Brazil
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