| 1. |
- Priyadarshini, Diana, et al.
(författare)
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Enzymatically Polymerized Organic Conductors on Model Lipid Membranes
- 2023
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Ingår i: Langmuir. - : AMER CHEMICAL SOC. - 0743-7463 .- 1520-5827. ; 39:23, s. 8196-8204
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Tidskriftsartikel (refereegranskat)abstract
- Seamless integration between biological systems and electricalcomponents is essential for enabling a twinned biochemical-electricalrecording and therapy approach to understand and combat neurologicaldisorders. Employing bioelectronic systems made up of conjugated polymers,which have an innate ability to transport both electronic and ioniccharges, provides the possibility of such integration. In particular,translating enzymatically polymerized conductive wires, recently demonstratedin plants and simple organism systems, into mammalian models, is ofparticular interest for the development of next-generation devicesthat can monitor and modulate neural signals. As a first step towardachieving this goal, enzyme-mediated polymerization of two thiophene-basedmonomers is demonstrated on a synthetic lipid bilayer supported ona Au surface. Microgravimetric studies of conducting films polymerizedin situ provide insights into their interactions with a lipid bilayermodel that mimics the cell membrane. Moreover, the resulting electricaland viscoelastic properties of these self-organizing conducting polymerssuggest their potential as materials to form the basis for novel approachesto in vivo neural therapeutics.
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| 2. |
- Qian, D. P., et al.
(författare)
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Modulating molecular aggregation by facile heteroatom substitution of diketopyrrolopyrrole based small molecules for efficient organic solar cells
- 2015
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 3:48, s. 24349-24357
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Tidskriftsartikel (refereegranskat)abstract
- In conjugated polymers and small molecules of organic solar cells, aggregation induced by intermolecular interactions governs the performance of photovoltaics. However, little attention has been paid to the connection between molecular structure and aggregation within solar cells based on soluble small molecules. Here we demonstrate modulation of intermolecular aggregation of two synthesized molecules through heteroatom substitution to develop an understanding of the role of aggregation in conjugated molecules. Molecule 1 (M1) based on 2-ethylhexyloxy-benzene substituted benzo[1,2-b:4,5-b']dithiophene (BDTP) and diketopyrrolopyrrole (DPP) displays strong aggregation in commonly used organic solvents, which is reduced in molecule 2 (M2) by facile oxygen atom substitution on the BDTP unit confirmed by absorption spectroscopy and optical microscopy, while it successfully maintains molecular planarity and favorable charge transport characteristics. Solar cells based on M2 exhibit more than double the photocurrent of devices based on M1 and yield a power conversion efficiency of 5.5%. A systematic investigation of molecular conformation, optoelectronic properties, molecular packing and crystallinity as well as film morphology reveals structure dependent aggregation responsible for the performance difference between the two conjugated molecules.
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| 3. |
- Sekretaryova, Alina, et al.
(författare)
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A highly sensitive and self-powered cholesterol biosensor
- 2014
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Ingår i: 24<sup>th </sup>Anniversary World Congress on Biosensors – Biosensors 2014. - : Elsevier.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Blood cholesterol is a very important parameter for the assessment of atherosclerosis and other lipid disorders. The total cholesterol concentration in human blood should be less than 5.17 mM. Concentrations in the range 5.17 – 6.18 mM are considered borderline high risk and levels above 6.21 mM, high risk. Cholesterol determination with high accuracy is therefore necessary in order to differentiate these levels for medical screening or diagnosis. Several attempts to develop highly sensitive cholesterol biosensors have been described, but, to the best of our knowledge, this is the first report of a self-powered cholesterol biosensor, i.e. a device delivering the analytical information from the current output of the energy of the biocatalytic conversion of cholesterol, without any external power source. This is particularly relevant to the development of inexpensive screening devices based on printed electronics. We present two complementary bioelectrocatalytic platforms suitable for the fabrication of a self-powered biosensor. Both are based on cholesterol oxidase (ChOx) immobilisation in a sol-gel matrix, as illustrated in Fig. 1 [1]. Mediated biocatalytic cholesterol oxidation [2] was used as the anodic reaction and electrocatalytic reduction of hydrogen peroxide on Prussian Blue (PB) as the cathodic reaction. Due to a synergistic effect in the self-powered cholesterol biosensor, the analytical parameters of the overall device exceeded those of the individual component half-cells, yielding a sensitivity of 0.19 A M-1 cm-2 and a dynamic range that embraces the free cholesterol concentrations found in human blood. Thus, we have demonstrated the novel concept of highly sensitive cholesterol determination using the first self-powered cholesterol biosensor. This configuration is particularly promising for incorporation in emerging plastic- and paper-based analytical instruments for decentralised diagnostics and mobile health.
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| 4. |
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| 5. |
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| 6. |
- Vagin, Mikhail Y, et al.
(författare)
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Boron-doped diamond microelectrode arrays for electrochemical monitoring of antibiotics contamination in water
- 2014
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Ingår i: 15<sup>th</sup> International Conference on Electroanalysis (ESEAC).
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The improvement of water management and increasing the access to safe drinking water can develop the quality of life for millions of people world-wide and reduce child mortality due to water-borne diseases [1]. Sweden was recently affected by the lack of appropriate water management which resulted in microbial contamination and tens of thousands of people falling ill [2]. Pollution with chemical compounds is also a waterworks concern. The appearance of pharmaceuticals such as antibiotics in raw water affects the cleaning processes at waterworks [3]. Substances which are not, or are only partly, eliminated in the sewage treatment plant will reach the surface water where they may affect organisms of different trophic levels and cause, for example, the of antibiotics resistance [4]. The inhibition of bacteria of waste water plants by antibiotics may seriously affect organic matter degradation. The efficiency of nitrification as an important step in waste water purification, can be decreased by antibiotics inhibition [5]. Boron-doped diamond (BDD) is an advanced electrode material that possesses the combination of good electrical conductivity achieved via film doping and the extreme chemical inertness of diamond, which gives rise to a number of highly desirable properties of BDD as electrode material: a wide potential window in aqueous media allows electrochemical measurements at both extreme anodic and cathodic potentials, very low capacitive currents leads to a sensitivity increase and extreme chemical and structural inertness prevents electrode fouling [6]. Usage of a microelectrode array as the working electrode offers a variety of benefits for electroanalysis: an improvement of the analytical performance in comparison with macroelectrodes under planar diffusion, higher signal-to-noise ratios due to low capacitive currents at the small surface area, shorter response times and less sensitivity to variations in the water flow rate. The BDD arrays of this work contain 2900 microelectrodes (10 mm diameter each) and have been used for the detection of antibiotics (ofloxacine and canamycin A) in water with high amplitude pulse voltammetry processed by multivariate data analysis. The detection limits observed in monitoring mode were comparable with the characteristics of standard protocols of antibiotics detection, which opens the possibility for continuous monitoring of water.[1] The United Nations, World Water Development Report 4, 2012; [2] Lindberg, A. et al.,FOI-R--3376--SE, 2011; Dryselius, R.; National Food Agency, Sweden, 2012; [3] KummererK. Chemosphere, 2009, 75, 417; [4] Kummerer K. Chemosphere, 2009, 75, 435; [5]Dokianakis, S.N. et al., Water Sci. Technol. 50, 341; [6] Goeting, C. et al.,NewDiam.Front.C.Tech. 1999, 9, 207; Compton, R. et al., Electroanal. 2003, 15, 1349.
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| 7. |
- Vagin, Mikhail Y, et al.
(författare)
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Screen-printed graphite microbands as a versatile biosensor platform
- 2014
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Ingår i: 24th Anniversary World Congress on Biosensors – Biosensors 2014. - : Elsevier.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The use of extremely small working electrodes offers a variety of benefits for electroanalysis. The enhanced mass transport as a result of convergent diffusion is the most important advantage of microdimensional electrodes and results in improved of analytical performance The low detectable-currents problem can be solved by single microelectrode multiplication into an array, thus combining the advantages of enhanced mass transport and high output signals. The microband is one of the most cost-effective and easy-fabricated geometries for microelectrodes. The microband width is a critical microscopic dimension of the electrode, which maintains the dominance of convergent diffusion, whereas the microband length is macroscopic and ensures registration of high currents.Graphite screen-printing on a plastic support is a standard technology for large-scale production of low cost electrochemical devices. This has been combined with simple guillotine cutting to fabricate of microband arrays for autonomous environmental and clinical monitoring.Single-layer and multilayer microband arrays of different band lengths were produced and characterised using optical and electrochemical methods. The critical dimension for the microband width to facilitate convergent diffusion was assessed electrochemically and found to be in the order of 5 microns. The developed electrode structures were used as a versatile platform for the manufacture of model electroanalytical systems. Direct oxidation of ascorbic acid was explored at the microband arrays and a glucose biosensor based on mediated and immobilised glucose oxidase was fabricated. Both examples yielded significant enhancement of the analytical performance.A: the layout of the screen-printed graphite microband array of 5 electrode layers. B: voltammmetric responses obtained at the microband arrays.Acknowledgement: Formas and Security Link for financial support; David Nilsson (Acreo) for screen-printing.
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| 8. |
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| 9. |
- Zhybak, Mikael, et al.
(författare)
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Copper/Nafion/PANI Nanocomposite as an electrochemical transducer for creatinine and urea enzymatic biosensing
- 2014
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Ingår i: <em>24th Anniversary World Congress on Biosensors – Biosensors 2014</em>. - : Elsevier.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Chronic Kidney diseases (CKD) affect, to different degrees, ca. 25 million Americans and 19 million Europeans. Monitoring of creatinine and urea levels is of great importance for a correct evaluation of the status of patients and for their treatment. In this paper, we present the development of creatinine and urea enzymatic biosensors, based on a novel ammonium ion-specific Copper/Nafion/Polyanyline (PANI) nanocomposite electrode (Fig. 1A), and suitable for PoC and decentralised diagnostic applications. . Studies on the nanocomposite electrode revealed its high sensitivity and specificity towards ammonium, in respect to amino acids, creatinine and urea, with response range between 5 and 75 μM (Fig. 1B) and with a detection limit of 1 μM. To demonstrate its suitability as transducer in biosensors, creatinine and urea biosensors were fabricated by immobilising creatinine deiminase or urease, respectively, on the nanocomposite surface. Optimisation of the enzyme immobilisation demonstrated that the incorporation of lactitol markedly improved the stability of the biosensors. The response range of the creatinine biosensor was 2 to 100 μM, which fits well with the normal levels of creatinine in healthy people (30-150 µM).The urea biosensor had a response range of 5 to 100 µM. A limit of quantification of 1 µM was achieved for both the biosensors.Evaluation of the performance of the biosensors in real sample matrices and cross reactivity studies are currently on-going. We envisage that the proposed design will be particularly compatible with fully-printed systems thus offering a viable route to the mass production of inexpensive sensors for mobile health.
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| 10. |
- Zhybak, M.T., et al.
(författare)
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Creatinine and urea biosensors based on a novel ammonium ion-selective copper-polyaniline nano-composite
- 2016
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Ingår i: Biosensors & bioelectronics. - : Elsevier. - 0956-5663 .- 1873-4235. ; 77, s. 505-511
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Tidskriftsartikel (refereegranskat)abstract
- The use of a novel ammonium ion-specific copper-polyaniline nano-composite as transducer for hydrolase-based biosensors is proposed. In this work, a combination of creatinine deaminase and urease has been chosen as a model system to demonstrate the construction of urea and creatinine biosensors to illustrate the principle. Immobilisation of enzymes was shown to be a crucial step in the development of the biosensors; the use of glycerol and lactitol as stabilisers resulted in a significant improvement, especially in the case of the creatinine, of the operational stability of the biosensors (from few hours to at least 3 days). The developed biosensors exhibited high selectivity towards creatinine and urea. The sensitivity was found to be 85±3.4 mA M−1 cm−2 for the creatinine biosensor and 112±3.36 mA M−1 cm−2 for the urea biosensor, with apparent Michaelis–Menten constants (KM,app), obtained from the creatinine and urea calibration curves, of 0.163 mM for creatinine deaminase and 0.139 mM for urease, respectively. The biosensors responded linearly over the concentration range 1–125 µM, with a limit of detection of 0.5 µM and a response time of 15 s.The performance of the biosensors in a real sample matrix, serum, was evaluated and a good correlation with standard spectrophotometric clinical laboratory techniques was found.
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