Research

2113 KiB

Open AccessArticle

Behaviour of Zinc Complexes and Zinc Sulphide Nanoparticles Revealed by Using Screen Printed Electrodes and Spectrometry

by Lukas Nejdl, Branislav Ruttkay-Nedecky, Jiří Kudr, Monika Kremplova, Natalia Cernei, Jan Prasek, Marie Konecna, Jaromir Hubalek, Ondrej Zitka, Jindrich Kynicky, Pavel Kopel, Rene Kizek and Vojtech Adam

Sensors 2013, 13(11), 14417-14437; https://doi.org/10.3390/s131114417 - 25 Oct 2013

Cited by 15 | Viewed by 9090

Abstract

In this study, we focused on microfluidic electrochemical analysis of zinc complexes (Zn(phen)(his)Cl₂, Zn(his)Cl₂) and ZnS quantum dots (QDs) using printed electrodes. This method was chosen due to the simple (easy to use) instrumentation and variable setting of flows. [...] Read more.

In this study, we focused on microfluidic electrochemical analysis of zinc complexes (Zn(phen)(his)Cl₂, Zn(his)Cl₂) and ZnS quantum dots (QDs) using printed electrodes. This method was chosen due to the simple (easy to use) instrumentation and variable setting of flows. Reduction signals of zinc under the strictly defined and controlled conditions (pH, temperature, flow rate, accumulation time and applied potential) were studied. We showed that the increasing concentration of the complexes (Zn(phen)(his)Cl₂, Zn(his)Cl₂) led to a decrease in the electrochemical signal and a significant shift of the potential to more positive values. The most likely explanation of this result is that zinc is strongly bound in the complex and its distribution on the electrode is very limited. Changing the pH from 3.5 to 5.5 resulted in a significant intensification of the Zn(II) reduction signal. The complexes were also characterized by UV/VIS spectrophotometry, chromatography, and ESI-QTOF mass spectrometry. Full article

(This article belongs to the Special Issue Multimetallic Nanoparticles for Chemical/Biological Sensing Applications)

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649 KiB

Open AccessArticle

A Gold Nanoparticles Enhanced Surface Plasmon Resonance Immunosensor for Highly Sensitive Detection of Ischemia-Modified Albumin

by Guang Li, Xian Li, Meng Yang, Meng-Meng Chen, Long-Cong Chen and Xing-Liang Xiong

Sensors 2013, 13(10), 12794-12803; https://doi.org/10.3390/s131012794 - 25 Sep 2013

Cited by 29 | Viewed by 8284

Abstract

In this study a novel sensitive nanogold particle sensor enhancement based on mixed self-assembled monolayers was explored and used to construct a Surface Plasmon Resonance (SPR) immunosensor to detect Ischemia Modified Albumin (IMA). Compared with a direct binding SPR assay at a limit [...] Read more.

In this study a novel sensitive nanogold particle sensor enhancement based on mixed self-assembled monolayers was explored and used to construct a Surface Plasmon Resonance (SPR) immunosensor to detect Ischemia Modified Albumin (IMA). Compared with a direct binding SPR assay at a limit of detection (LOD) of 100 ng/L, gold nanoparticles (AuNPs) of 10 nm dramatically improved the LOD of IMA to 10 ng/L. Meanwhile, no interfering substance that may lead to false positive results was identified. These results suggested that the SPR biosensor presented superior properties, and provided a simple label-free strategy to increase assay sensitivity for further acute coronary syndrome (ACS) diagnosis. Full article

(This article belongs to the Special Issue Multimetallic Nanoparticles for Chemical/Biological Sensing Applications)

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485 KiB

Open AccessArticle

Synthesis of Bimetallic Platinum Nanoparticles for Biosensors

by Gerard M. Leteba and Candace I. Lang

Sensors 2013, 13(8), 10358-10369; https://doi.org/10.3390/s130810358 - 12 Aug 2013

Cited by 25 | Viewed by 8685

Abstract

The use of magnetic nanomaterials in biosensing applications is growing as a consequence of their remarkable properties; but controlling the composition and shape of metallic nanoalloys is problematic when more than one precursor is required for wet chemistry synthesis. We have developed a [...] Read more.

The use of magnetic nanomaterials in biosensing applications is growing as a consequence of their remarkable properties; but controlling the composition and shape of metallic nanoalloys is problematic when more than one precursor is required for wet chemistry synthesis. We have developed a successful simultaneous reduction method for preparation of near-spherical platinum-based nanoalloys containing magnetic solutes. We avoided particular difficulties in preparing platinum nanoalloys containing Ni, Co and Fe by the identification of appropriate synthesis temperatures and chemistry. We used transmission electron microscopy (TEM) to show that our particles have a narrow size distribution, uniform size and morphology, and good crystallinity in the as-synthesized condition. Energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) confirms the coexistence of Pt with the magnetic solute in a face-centered cubic (FCC) solid solution. Full article

(This article belongs to the Special Issue Multimetallic Nanoparticles for Chemical/Biological Sensing Applications)

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692 KiB

Open AccessArticle

Nano-Molar Deltamethrin Sensor Based on Electrical Impedance of PAH/PAZO Layer-by-Layer Sensing Films

by Luís Miguel Gomes Abegão, Jorge Humberto Fernandes Ribeiro, Paulo António Ribeiro and Maria Raposo

Sensors 2013, 13(8), 10167-10176; https://doi.org/10.3390/s130810167 - 08 Aug 2013

Cited by 16 | Viewed by 6903

Abstract

This work reports a novel deltamethrin (DM) sensor able to detect nano-molar concentrations in ethanol solutions. The sensing layer consists of a thin film, obtained via a layer-by-layer technique, from alternate adsorption of poly(allylamine chloride) (PAH) and poly[1-[4-(3-carboxy-4-hydroxyphenylazo)-benzenesulfonamide)-1,2-ethanediyl]sodium salt] (PAZO) onto a solid [...] Read more.

This work reports a novel deltamethrin (DM) sensor able to detect nano-molar concentrations in ethanol solutions. The sensing layer consists of a thin film, obtained via a layer-by-layer technique, from alternate adsorption of poly(allylamine chloride) (PAH) and poly[1-[4-(3-carboxy-4-hydroxyphenylazo)-benzenesulfonamide)-1,2-ethanediyl]sodium salt] (PAZO) onto a solid support with interdigitaded gold electrodes. The sensor response, obtained from impedance spectroscopy measurements, was revealed to be linear with respect to the real part of impedance, taken at 100 Hz, when plotted as a function of the logarithm of deltamethrin molar concentrations in the micro- to nano-molar range. Sensor sensitivity was of 41.1 ± 0.7 kΩ per decade of concentration for an immersion time above 2 min and the reproducibility is approximately 2% in a binary solution of ethanol and deltamethrin. The main insight of this work concerns to DM detection limits as the sensor revealed to be able to detect concentrations below 0.1 nM, a value which is significantly lower than any reported in the literature and close what is appropriate for in situ environmental contaminant detection. Full article

(This article belongs to the Special Issue Multimetallic Nanoparticles for Chemical/Biological Sensing Applications)

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596 KiB

Open AccessArticle

Rapid Quantitative Detection of Brucella melitensis by a Label-Free Impedance Immunosensor Based on a Gold Nanoparticle-Modified Screen-Printed Carbon Electrode

by Haiyun Wu, Yueming Zuo, Chuanjin Cui, Wei Yang, Haili Ma and Xiaowen Wang

Sensors 2013, 13(7), 8551-8563; https://doi.org/10.3390/s130708551 - 04 Jul 2013

Cited by 46 | Viewed by 8623

Abstract

A rapid and simple method for quantitative monitoring of Brucella melitensis using electrochemical impedance spectroscopy (EIS) is reported for the first time. The label-free immunosensors were fabricated by immobilizing Brucella melitensis antibody on the surface of gold nanoparticle-modified screen-printed carbon electrodes (GNP-SPCEs). Cyclic [...] Read more.

A rapid and simple method for quantitative monitoring of Brucella melitensis using electrochemical impedance spectroscopy (EIS) is reported for the first time. The label-free immunosensors were fabricated by immobilizing Brucella melitensis antibody on the surface of gold nanoparticle-modified screen-printed carbon electrodes (GNP-SPCEs). Cyclic voltammetry (CV) and EIS were used to characterize the Brucella melitensis antigen interaction on the surface of GNP-SPCEs with antibody. A general electronic equivalent model of an electrochemical cell was introduced for interpretation of the impedance components of the system. The results showed that the change in electron-transfer resistance (R_ct) was significantly different due to the binding of Brucella melitensis cells. A linear relationship between the R_ct variation and logarithmic value of the cell concentration was found from 4 × 10⁴ to 4 × 10⁶ CFU/mL in pure culture. The label-free impedance biosensor was able to detect as low as 1 × 10⁴ and 4 × 10⁵ CFU/mL of Brucella melitensis in pure culture and milk samples, respectively, in less than 1.5 h. Moreover, a good selectivity versus Escherichia coli O157:H7 and Staphylococcus aureus cells was obtained for our developed immunosensor demonstrating its specificity towards only Brucella melitensis. Full article

(This article belongs to the Special Issue Multimetallic Nanoparticles for Chemical/Biological Sensing Applications)

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652 KiB

Open AccessArticle

Transverse Susceptibility as a Biosensor for Detection of Au-Fe₃O₄ Nanoparticle-Embedded Human Embryonic Kidney Cells

by Natalie Frey Huls, Manh-Huong Phan, Arun Kumar, Subhra Mohapatra, Shyam Mohapatra, Pritish Mukherjee and Hariharan Srikanth

Sensors 2013, 13(7), 8490-8500; https://doi.org/10.3390/s130708490 - 03 Jul 2013

Cited by 8 | Viewed by 7149

Abstract

We demonstrate the possibility of using a radio-frequency transverse susceptibility (TS) technique based on a sensitive self-resonant tunnel-diode oscillator as a biosensor for detection of cancer cells that have taken up magnetic nanoparticles. This technique can detect changes in frequency on the order [...] Read more.

We demonstrate the possibility of using a radio-frequency transverse susceptibility (TS) technique based on a sensitive self-resonant tunnel-diode oscillator as a biosensor for detection of cancer cells that have taken up magnetic nanoparticles. This technique can detect changes in frequency on the order of 10 Hz in 10 MHz. Therefore, a small sample of cells that have taken up nanoparticles when placed inside the sample space of the TS probe can yield a signal characteristic of the magnetic nanoparticles. As a proof of the concept, Fe₃O₄ nanoparticles coated with Au (mean size ~60 nm) were synthesized using a micellar method and these nanoparticles were introduced to the medium at different concentrations of 0.05, 0.1, 0.5, and 1 mg/mL buffer, where they were taken up by human embryonic kidney (HEK) cells via phagocytosis. While the highest concentration of Au-Fe₃O₄ nanoparticles (1 mg/mL) was found to give the strongest TS signal, it is notable that the TS signal of the nanoparticles could still be detected at concentrations as low as 0.1 mg/mL. Full article

(This article belongs to the Special Issue Multimetallic Nanoparticles for Chemical/Biological Sensing Applications)

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1007 KiB

Open AccessArticle

Enhanced Electronic Properties of Pt@Ag Heterostructured Nanoparticles

by Anh Thi Ngoc Dao, Derrick M. Mott, Koichi Higashimine and Shinya Maenosono

Sensors 2013, 13(6), 7813-7826; https://doi.org/10.3390/s130607813 - 18 Jun 2013

Cited by 19 | Viewed by 8888

Abstract

Platinum coated by silver nanoparticles was synthesized, which displays a unique structure where polycrystalline platinum particles are completely encapsulated in continuous monocrystalline silver shells. These particles display accentuated electronic properties, where the silver shells gain electron density from the platinum cores, imparting enhanced [...] Read more.

Platinum coated by silver nanoparticles was synthesized, which displays a unique structure where polycrystalline platinum particles are completely encapsulated in continuous monocrystalline silver shells. These particles display accentuated electronic properties, where the silver shells gain electron density from the platinum cores, imparting enhanced properties such as oxidation resistance. This electron transfer phenomenon is highly interfacial in nature, and the degree of electron transfer decreases as the thickness of silver shell increases. The nanoparticle structure and electronic properties are studied and the implication to creating sensing probes with enhanced robustness, sensitivity and controllable plasmonic properties is discussed. Full article

(This article belongs to the Special Issue Multimetallic Nanoparticles for Chemical/Biological Sensing Applications)

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387 KiB

Open AccessArticle

Simple, Fast and Selective Detection of Adenosine Triphosphate at Physiological pH Using Unmodified Gold Nanoparticles as Colorimetric Probes and Metal Ions as Cross-Linkers

by Dehua Deng, Ning Xia, Sujuan Li, Chunying Xu, Ting Sun, Huan Pang and Lin Liu

Sensors 2012, 12(11), 15078-15087; https://doi.org/10.3390/s121115078 - 06 Nov 2012

Cited by 18 | Viewed by 8153

Abstract

We report a simple, fast and selective colorimetric assay of adenosine triphosphate (ATP) using unmodified gold nanoparticles (AuNPs) as probes and metal ions as cross-linkers. ATP can be assembled onto the surface of AuNPs through interaction between the electron-rich nitrogen atoms and the [...] Read more.

We report a simple, fast and selective colorimetric assay of adenosine triphosphate (ATP) using unmodified gold nanoparticles (AuNPs) as probes and metal ions as cross-linkers. ATP can be assembled onto the surface of AuNPs through interaction between the electron-rich nitrogen atoms and the electron-deficient surface of AuNPs. Accordingly, Cu²⁺ ions induce a change in the color and UV/Vis absorbance of AuNPs by coordinating to the triphosphate groups and a ring nitrogen of ATP. A detection limit of 50 nM was achieved, which is comparable to or lower than that achievable by the currently used electrochemical, spectroscopic or chromatographic methods. The theoretical simplicity and high selectivity reported herein demonstrated that AuNPs-based colorimetric assay could be applied in a wide variety of fields by rationally designing the surface chemistry of AuNPs. In addition, our results indicate that ATP-modified AuNPs are less stable in Cu²⁺, Cd²⁺ or Zn²⁺-containing solutions due to the formation of the corresponding dimeric metal-ATP complexes. Full article

(This article belongs to the Special Issue Multimetallic Nanoparticles for Chemical/Biological Sensing Applications)

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