We have reported previously on the existence of charge-induced long-range organization in the room-temperature ionic liquid (RTIL), BMIM+BF4-. The induced organization is in the form of a free charge density gradient (ρf) that exists over ca. 100 μm into the RTIL in contact with a charged surface. The fluorescence anisotropy decay of a trace-level charged chromophore in the RTIL is measured as a function of distance from the indium-doped tin oxide support surface to probe this free charge density gradient. We report here on the characterization of the free charge density gradient in five different imidazolium RTILs and use these data to evaluate the magnitude of the induced free charge density gradient. Both the extent and magnitude of this gradient depend on the chemical structures of the cationic and anionic constituents of the RTIL used. Control over the magnitude of ρf has implications for the utility of RTILs for a host of applications that remain to be explored fully.
- Publikační typ
- časopisecké články MeSH
Polyacrylamide-coated, carbon nanotube (PA/CNT) electrodes were prepared by an inkjet printing process and used to measure pyocyanin and uric acid in a wound fluid simulant at 37 °C. These two molecules are potential indicators of infection, and therefore their detection could prove useful for monitoring wound healing. Pyocyanin is a marker for the common wound bacterium Pseudomonas aeruginosa. Our long-term goal is to use these inexpensive and disposable electrodes to measure biomarkers of wound healing directly. In this proof-of-concept work, studies were performed in a wound fluid simulant to evaluate the stability of the electrodes and their responsiveness for the two bioanalytes. The PA/CNT inkjet-printed electrodes and electrical contacts were stable with unchanging physical and electrochemical properties in the wound fluid simulant over a 7-8-day period at 37 °C. The detection figures of merit for pyocyanin in the simulant at 37 °C were as follows: linear over the physiologically relevant range = 0.10 to 100 μmol L-1 (R2 = 0.9992), limit of detection = 0.10 μmol L-1 (S/N = 3), sensitivity = 35.6 ± 0.8 mA-L mol-1 and response variability ≤4% RSD. The detection figures of merit for uric acid in the simulant at 37 °C were as follows: linear over the physiologically relevant range = 100 to 1000 μmol L-1 (R2 = 0.9997), sensitivity = 2.83 ± 0.01 mA-L mol-1, and response variability ≤4% RSD. The limit of detection was not determined. The PA/CNT electrodes were also used to quantify pyocyanin concentrations in cell-free culture media from different strains of P. aeruginosa. The detected concentrations ranged from 1.00 ± 0.02 to 118 ± 6 μM depending on the strain.
- MeSH
- biosenzitivní techniky přístrojové vybavení MeSH
- design vybavení MeSH
- elektrody MeSH
- kultivační média analýza MeSH
- kyselina močová analýza MeSH
- nanotrubičky uhlíkové chemie MeSH
- Pseudomonas aeruginosa izolace a purifikace MeSH
- pyokyanin analýza MeSH
- rány a poranění mikrobiologie patologie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
- Názvy látek
- kultivační média MeSH
- kyselina močová MeSH
- nanotrubičky uhlíkové MeSH
- pyokyanin MeSH
We report on the analytical performance of a tetrahedral amorphous carbon (ta-C:N) thin-film electrode in flow injection analysis with amperometric detection. Two model redox analytes were used to evaluate the electrode response because of their positive detection potentials and propensity (i.e., reaction products) to adsorb and foul sp2 carbon electrodes: tyrosine and tryptophan. ta-C:N electrodes are attractive for electroanalytical applications because they possesses many of the excellent properties of boron-doped nanocrystalline diamond (BDD) and they can be deposited at or near room temperature. The results show that the ta-C:N electrode exhibits lower background current and noise than glassy carbon (GC). The electrode was stable microstructurally at the positive potentials used for detection, ∼1.1 V, of these two amino acids and it exhibited superior analytical detection figures of merit as compared to GC and as good or superior to BDD. The linear dynamic range for both analytes at ta-C:N was from 0.1 to 100 μmol L-1, the sensitivity was 8-12 mA L mol-1, the short-term response variability was 1-2%, and the minimum detectable concentration was 89.7 ± 0.9 nM (18.3 μg L-1 or 0.46 ng) for tryptophan and 120 ± 11 nM (21.7 μg L-1 or 0.54 ng) for tyrosine. The analytical detection figures of merit for these amino acids at GC and BDD are also presented for comparison as is characterization data for the chemical composition and microstructure of the ta-C:N film.
- Publikační typ
- časopisecké články MeSH
Correction for 'Evaluation of a nitrogen-incorporated tetrahedral amorphous carbon thin film for the detection of tryptophan and tyrosine using flow injection analysis with amperometric detection' by Romana Jarošová, et al., Analyst, 2016, DOI: .
- Publikační typ
- časopisecké články MeSH
- tisková chyba MeSH
