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| 3. |
- Asif, Muhammad, et al.
(författare)
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Functionalized ZnO nanorod-based selective magnesium ion sensor for intracellular measurements
- 2010
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Ingår i: Biosensors & bioelectronics. - : Elsevier Science B.V., Amsterdam.. - 0956-5663 .- 1873-4235. ; 26:3, s. 1118-1123
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Tidskriftsartikel (refereegranskat)abstract
- ZnO nanorods were grown on a silver-coated tip of a borosilicate glass capillary (0.7 mu m in tip diameter) and used as selective potentiometric sensor of intracellular free Mg2+. To functionalize the ZnO nanorods for selectivity of Mg2+, a polymeric membrane with Mg2+-selective ionophores were coated on the surface of the ZnO nanorods. These functionalized ZnO nanorods exhibited a Mg2+-dependent electrochemical potential difference versus an Ag/AgCl reference microelectrode within the concentration range from 500 nM to 100 mM. Two types of cells, human adipocytes and frog oocytes, were used for the intracellular Mg2+ measurements. The intracellular concentration of free Mg2+ in human adipocytes and frog oocytes were 0.4-0.5 and 0.8-0.9 mM, respectively. Such type of nanoelectrode device paves the way to enable analytical measurements in single living cells and to sense other bio-chemical species at the intracellular level.
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| 4. |
- Asif, Muhammad H, et al.
(författare)
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Functionalised ZnO-nanorod-based selective electrochemical sensor for intracellular glucose
- 2010
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Ingår i: Biosensors & Bioelectronics. - : Elsevier BV. - 1873-4235 .- 0956-5663. ; 25:10, s. 2205-2211
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Tidskriftsartikel (refereegranskat)abstract
- In this article, we report a functionalised ZnO-nanorod-based selective electrochemical sensor for intracellular glucose. To adjust the sensor for intracellular glucose measurements, we grew hexagonal ZnO nanorods on the tip of a silver-covered borosilicate glass capillary (0.7 mu m diameter) and coated them with the enzyme glucose oxidase. The enzyme-coated ZnO nanorods exhibited a glucose-dependent electrochemical potential difference versus an Ag/AgCl reference microelectrode. The potential difference was linear over the concentration range of interest (0.5-1000 mu M). The measured glucose concentration in human adipocytes or frog oocytes using our ZnO-nanorod sensor was consistent with values of glucose concentration reported in the literature; furthermore, the sensor was able to show that insulin increased the intracellular glucose concentration. This nanoelectrode device demonstrates a simple technique to measure intracellular glucose concentration. (C) 2010 Elsevier B.V. All rights reserved.
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| 5. |
- Basheer, Shabana, et al.
(författare)
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A membrane protein based biosensor: Use of a phosphate - H+ symporter membrane protein (Pho84) in the sensing of phosphate ions.
- 2011
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Ingår i: Biosensors & bioelectronics. - : Elsevier. - 0956-5663 .- 1873-4235. ; 27:1, s. 58-63
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Tidskriftsartikel (refereegranskat)abstract
- A label free biosensor for direct detection of inorganic phosphate based on potential-step capacitance measurements has been developed. The high-affinity Pho84 plasma membrane phosphate/proton symporter of Saccharomyces cerevisiae was used as a sensing element. Heterologously expressed and purified Pho84 protein was immobilized on a self-assembled monolayer (SAM) on a capacitance electrode. Changes in capacitance were recorded upon exposure to phosphate compared to the control substance, phosphate analogue methylphosphonate. Hence, even without the explicit use of lipid membranes, the Pho84 membrane protein could retain its capacity of selective substrate binding, with a phosphate detection limit in the range of the apparent in vivo K(m). A linear increase in capacitance was monitored in the phosphate concentration range of 5-25 mu M. The analytical response of the capacitive biosensor is in agreement with that the transporter undergoes significant conformational changes upon exposure to inorganic phosphate, while exposure to the analogue only causes minor responses.
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| 6. |
- Beni, Valerio, et al.
(författare)
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Development of a gold nano-particle-based fluorescent molecular beacon fordetection of cystic fibrosis associated mutation
- 2010
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Ingår i: Biosensors & bioelectronics. - : Elsevier. - 0956-5663 .- 1873-4235. ; 26:2, s. 307-313
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Tidskriftsartikel (refereegranskat)abstract
- Cystic fibrosis is one of the most common genetically inherited diseases in Northern Europe, consistingof an inherited defect of chloride transport in the epithelium. Of the several mutations related to CF, theF508 mutation occurs in ca. 70% of the cases. In this work the use of a gold nano-particle supportedfluorescence molecular beacon was investigated as an optical sensing platform for the detection of theF508 cystic fibrosis associated mutation. Different parameters such as molecular beacon design, Aunano-particle size, molecular beacon–nano-particle conjugation protocol, molecular beacon loading aswell as experimental conditions were evaluated. A 31-base long molecular beacon, containing a 15-baserecognition sequence specific for the mutant target, was linked via a thiol modified poly thymine linker(10 bases long) to a 13 nm gold nano-particle and was exposed to mutant and wild type targets, and aclear differentiation was achieved at target concentrations as low as 1 nM.
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| 7. |
- Berti, Francesca, et al.
(författare)
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Quasi-monodimensional polyaniline nanostructures for enhanced molecularly imprinted polymer-based sensing
- 2010
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Ingår i: Biosensors & bioelectronics. - : Elsevier Science B.V., Amsterdam.. - 0956-5663 .- 1873-4235. ; 26:2, s. 497-503
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Tidskriftsartikel (refereegranskat)abstract
- Recent advances in nanotechnology have allowed significant progress in utilising cutting-edge techniques associated with nanomaterials and nano-fabrication to expand the scope and capability of biosensors to a new level of novelty and functionality. The aim of this work was the development and characterisation of conductive polyaniline (PANI) nanostructures for applications in electrochemical biosensing. We explore a simple, inexpensive and fast route to grow PANI nanotubes, arranged in an ordered structure directly on an electrode surface, by electrochemical polymerisation using alumina nanoporous membranes as a nano-mould. The deposited nanostructures have been characterised electrochemically and morphologically prior to grafting with a molecularly imprinted polymer (MIP) receptor in order to create a model sensor for catechol detection. In this way, PANI nanostructures resulted in a conductive nanowire system which allowed direct electrical connection between the electrode and the synthetic receptor (MIP). To our knowledge, this is the first example of integration between molecularly imprinted polymers and PANI nanostructured electrodes. The advantages of using nanostructures in this particular biosensing application have been evaluated by comparing the analytical performance of the sensor with an analogous non-nanostructured MIP-sensor for catechol detection that was previously developed. A significantly lower limit of detection for catechol has been obtained (29 nM, one order of magnitude), thus demonstrating that the nanostructures are capable of improving the analytical performance of the sensor. (C) 2010 Elsevier B.V. All rights reserved.
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| 8. |
- Bini, Alessandra, et al.
(författare)
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Selection of thrombin-binding aptamers by using computational approach for aptasensor application
- 2011
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Ingår i: Biosensors & bioelectronics. - : Elsevier. - 0956-5663 .- 1873-4235. ; 26:11, s. 4411-4416
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Tidskriftsartikel (refereegranskat)abstract
- The possibility of introducing a computationally assisted method to study aptamer-protein interaction was evaluated with the aim of streamlining the screening and selection of new aptamers. Starting from information on the 15-mer (5-GGTTGGTGTGGTTGG-3 thrombin binding aptamer (TBA), a library of mutated DNA sequences (994 elements) was generated and screened using shapegauss a shape-based scoring function from openeye software to generate computationally derived binding scores. The TBA and three other mutated oligonucleotides, selected on the basis of their binding score (best, medium, worst), were incorporated into surface plasmon resonance (SPR) biosensors. By reducing the ionic strength (binding buffer, 50 mMTrisHC1pH 7.4, 140 mM NaCl, 1 mM MgCl(2), diluted 1:50) in order to match the simulated condition, the analytical performances of the four oligonucleotide sequences were compared using signal amplitude, sensitivity (slope), linearity (R(2)) and reproducibility (CVav %). The experimental results were in agreement with the simulation findings.
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| 9. |
- Chen, Ying, et al.
(författare)
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Dual-signal analysis eliminates requirement for milk sample pretreatment.
- 2011
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Ingår i: Biosensors & Bioelectronics. - : Elsevier BV. - 1873-4235 .- 0956-5663. ; 29:1, s. 115-118
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Tidskriftsartikel (refereegranskat)abstract
- Detection of analytes in complex biological samples, such as milk and blood, normally requires sample pretreatment. These pretreatment regimes reduce assay throughput and increase testing costs. Technologies that make it possible to eliminate sample pretreatment are of great industrial interest. Here we report the development of a dual-signal flow injected analysis device which eliminates the need for sample pretreatment. The device employs thermal traducers to measure the signal from an enzyme and a reference column. This makes it possible to independently monitor and correct for non-specifically generated heat, thereby eliminating the need for sample pretreatment. The ability of the dual-signal device to determine urea and lactate in milk samples without any prior treatment was evaluated. The spiked milk samples, the urea assay had a linear range from 0.1 to 50mM (R=0.996), and the lactate assay had a linear range from 0.025 to 5.0mM (R=0.9998). The linear regression values for urea and lactate for 0.5%, 1.5% and 3.0% fat milk were at least 0.990. The dual-signal design improves assay reproducibility, accuracy and sensitivity. Addition benefits are shorter assay times and lowers costs, as well as reducing equipment and training requirements. The potential application of the technology for multi-analyte analysis in point of care and decentralized diagnostic testing in healthcare, agriculture and environmental areas is discussed.
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| 10. |
- Falk, Magnus, et al.
(författare)
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Biofuel cell as a power source for electronic contact lenses
- 2012
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Ingår i: Biosensors & bioelectronics. - : Elsevier. - 0956-5663 .- 1873-4235. ; 37:1, s. 38-45
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Tidskriftsartikel (refereegranskat)abstract
- Here we present unequivocal exptl. proof that microscale cofactor- and membrane-less, direct electron transfer based enzymic fuel cells do produce significant amts. of elec. energy in human lachrymal liq. (tears). 100 μm diam. gold wires, covered with 17 nm gold nanoparticles, were used to fashion three-dimensional nanostructured microelectrodes, which were biomodified with Corynascus thermophilus cellobiose dehydrogenase and Myrothecium verrucaria bilirubin oxidase as anodic and cathodic bioelements, resp. The following characteristics of miniature glucose/oxygen biodevices operating in human tears were registered: 0.57 V open-circuit voltage, about 1 μW cm-2 max. power d. at a cell voltage of 0.5 V, and more than 20 h operational half-life. Theor. calcns. regarding the max. recoverable elec. energy can be extd. from the biofuel and the biooxidant, glucose and mol. oxygen, each readily available in human lachrymal liq., fully support our belief that biofuel cells can be used as elec. power sources for so called smart contact lenses.
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