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, Hungwei Chang, Gustavo Serrano, Edward T. Zellers
Published: 1 January 2011
Journal: The Analyst
The Analyst, Volume 136, pp 1664-1674; https://doi.org/10.1039/c0an00780c

Abstract:
This article describes the development and characterization of a multi-stage preconcentrator/focuser (PCF) module designed to be integrated with a microfabricated gas chromatograph (µGC) for autonomous, in situ determinations of volatile organic compounds. The PCF module has been optimized specifically for the determination of trichloroethylene (TCE) vapors at low- or sub-parts-per-billion concentrations in the presence of common indoor air co-contaminants in residences at risk of vapor intrusion (VI) from surrounding TCE-contaminated soil. It consists of three adsorbent-packed devices arranged in series: a pre-trap of conventional (tubular metal) design for capturing interferences with vapor pressures <3 torr; a high-volume sampler, also of conventional design, for capturing (and transferring) TCE and other compounds with vapor pressures within the range of 3 to 95 torr; and a microfocuser (µF) consisting of a micromachined Si chamber with an integrated microheater for focusing and injecting samples into the separation module. The adsorbent masses, sampling and desorption flow rates, and heating profiles required for selective, quantitative capture and transfer/injection of TCE are determined for each of the devices, and the assembled PCF module is used to analyze a test atmosphere containing 200 parts-per-trillion of TCE and 27 relevant co-contaminants with a conventional downstream capillary column and electron-capture detector. An average TCE transfer efficiency of 107% is achieved for a 20 L air sample, with a preconcentration factor of 800000.
Published: 10 October 2017
Journal: The Analyst
The Analyst, Volume 143, pp 33-59; https://doi.org/10.1039/c7an01266g

Abstract:
Coherent Raman imaging provides information that could be key to improving analysis of tissues for cancer diagnosis.
Published: 1 January 2017
Journal: The Analyst
The Analyst, Volume 142, pp 3761-3761; https://doi.org/10.1039/c7an90077e

Abstract:
A graphical abstract is available for this content
Published: 1 January 2017
Journal: The Analyst
The Analyst, Volume 142, pp 3762-3762; https://doi.org/10.1039/c7an90078c

Abstract:
A graphical abstract is available for this content
Published: 1 January 2017
Journal: The Analyst
The Analyst, Volume 142, pp 3995-3996; https://doi.org/10.1039/c7an90080e

Abstract:
A graphical abstract is available for this content
Published: 3 June 2003
Journal: The Analyst
The Analyst, Volume 128, pp 879-883; https://doi.org/10.1039/b304371a

Abstract:
The analysis of Pelargonium graveolens essential oil is reported using comprehensive two-dimensional gas chromatography with quadrupole mass spectrometric detection (GC×GC-qMS). A spectral acquisition rate of 20 Hz was achieved by using a reduced mass scan range of 188 u. 65 components were identified within the two-dimensional separation space based upon retention index and mass spectral matching with literature data. Very high quality mass spectra were obtained, which facilitated accurate library matching, without the need for background correction. High efficiency in the short, fast-GC second dimension column was achieved by applying the principles of vacuum-GC. It is demonstrated that facile determination of the key citronellol : geraniol ratio and the amount of 10-epi-γ-eudesmol in geranium essential oils using GC×GC will be possible. The method should be generally suited to the analysis of similar essential oil samples.
, Margherita Dell'Aica, Matthias Jender, , ,
Published: 4 October 2017
Journal: The Analyst
The Analyst, Volume 142, pp 4228-4239; https://doi.org/10.1039/c7an01514c

Abstract:
A general difficulty in the miniaturization of free-flow electrophoresis relates to the need to separate electrodes and separation bed compartments.
, Melanie Keß, , Sigurd Schulte-Hostede
Published: 15 December 2010
Journal: The Analyst
The Analyst, Volume 136, pp 692-695; https://doi.org/10.1039/c0an00699h

Abstract:
A proof of concept for the simultaneous multi-parameter determination of three inflammation and sepsis parameters—TNFα, PCT and CRP—using a compact optical immunosensor is demonstrated. Harmonized assay conditions revealed standard curves with test midpoints (IC50) of 380 µg L−1 for TNFα, 2300 µg L−1 for PCT, and 2645 µg L−1 for CRP.
, Maxie Kohler, Wilhelm Schänzer, Philippe Delahaut,
Published: 15 December 2010
Journal: The Analyst
The Analyst, Volume 136, pp 1003-1012; https://doi.org/10.1039/c0an00632g

Abstract:
Peptide analysis in doping controls by means of nano-UPLC coupled high resolution/high mass accuracy mass spectrometry provides the state-of-the-art technique in modern sports drug testing. The present study describes a recent application of this technique for the qualitative determination of different urinary insulin-like growth factor (IGF) related peptides. After simultaneous isolation by solid phase extraction and magnetic particle-based immunoaffinity purification, target analytes (IGF-1, IGF-2, Des1-3-IGF-1, R3-IGF-1 and longR3-IGF-1) were separated by nano-liquid chromatography prior to mass spectrometric detection. Endogenously produced IGF-1 and IGF-2, as well as the degradation product Des1-3-IGF-1, were frequently detected in urine samples from healthy volunteers in a concentration range of 20–400 pg mL−1. The impact of IGF binding proteins (IGFBPs), being also present in urine, was potentially estimated by an additional ultrafiltration step in the sample preparation procedure. The synthetic analogue longR3-IGF-1, which is assumed to be subject to misuse by cheating athletes, was also analysed and detected in fortified urine samples. Besides the intact molecule, an N-terminally truncated degradation product Des1-10-longR3-IGF-1 was identified as the more stable target for doping controls using urine samples. The method was validated for qualitative purposes considering the parameters specificity, limit of detection (20–50 pg mL−1), recovery (10–35%), precision (<20%), linearity, robustness and stability.
, Marie-Pier Murray-Méthot, Ludovic S. Live
Published: 31 March 2010
Journal: The Analyst
The Analyst, Volume 135, pp 1483-1489; https://doi.org/10.1039/c0an00053a

Abstract:
Since the last decade, nanohole arrays have emerged from an interesting optical phenomenon to the development of applications in photophysical studies, photovoltaics and as a sensing template for chemical and biological analyses. Numerous methodologies have been designed to manufacture nanohole arrays, including the use of focus ion beam milling, soft-imprint lithography, colloidal lithography and, more recently, modified nanosphere lithography (NSL). With NSL or colloidal lithography, the experimental conditions control the density of the nanosphere mask and, thus, the aspect of the nanohole arrays. Low surface coverage of the nanosphere mask produces disordered nanoholes. Ordered nanohole arrays are obtained with a densely packed nanosphere mask in combination with electrochemical deposition of the metal, glancing angle deposition (GLAD) or etching of the nanospheres prior to metal deposition. A review of these methodologies is presented here with an emphasis on the optical properties of nanoholes interesting in analytical chemistry. In particular, applications of these novel plasmonic materials will be demonstrated as substrates for a localized surface plasmon resonance (LSPR), Surface Plasmon Resonance (SPR), surface enhanced Raman spectroscopy (SERS), and in electrochemistry with nano-patterned electrodes.
Bedabrata Saha, Pål Songe, Toon H. Evers,
Published: 17 October 2017
Journal: The Analyst
The Analyst, Volume 142, pp 4247-4256; https://doi.org/10.1039/c7an01424d

Abstract:
Antibody accessibility on the nanoparticle surface depends on the surface density rather than on the coupling conditions.
, L. L. Goddard, G. L. Liu
Published: 17 October 2017
Journal: The Analyst
The Analyst, Volume 142, pp 4422-4430; https://doi.org/10.1039/c7an00630f

Abstract:
A plasmonic nanocone SERS substrate with a uniform enhancement factor is developed and applied for cell lysate studies.
Jin-Xiu Zhou, Li-Na Tang, , , Hua Wang, Yu-Tao Li,
Published: 13 October 2017
Journal: The Analyst
The Analyst, Volume 142, pp 4322-4329; https://doi.org/10.1039/c7an01446e

Abstract:
MoS2/Pt nanocomposites functionalized acupuncture needle for real-time monitoring of H2O2 release from living cells.
Correction
, Miaomiao Zhang, Xuejuan Chen, Xingxing Ma, Chen Li, Zhe Zhang, Jilin Tang
Published: 26 October 2017
Journal: The Analyst
The Analyst, Volume 142, pp 4330-4330; https://doi.org/10.1039/c7an90085f

Abstract:
Correction for ‘Mapping the interaction sites of Mucin 1 and DNA aptamer by atomic force microscopy’ by Nan Wang, et al., Analyst, 2017, 142, 3800–3804.
David W. Frederick, , Alexia Buas, Jason Goodspeed, Jay Singh, Clementina Mesaros, Joseph A. Baur,
Published: 18 October 2017
Journal: The Analyst
The Analyst, Volume 142, pp 4431-4437; https://doi.org/10.1039/c7an01378g

Abstract:
Nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP) are conserved metabolic cofactors that mediate reduction-oxidation (redox) reactions throughout all domains of life.
Published: 6 October 2017
Journal: The Analyst
The Analyst, Volume 142, pp 4173-4200; https://doi.org/10.1039/c7an00455a

Abstract:
This critical review provides an overview of sensitivity-enhancement strategies and a systematic, quantitative analysis of field-effect transistor (IS-FET/BioFET) sensor literature.
Mark DeWaele, Yoonbae Oh, Cheonho Park, Yu Min Kang, Hojin Shin, Charles D. Blaha, Kevin E. Bennet, In Young Kim, Kendall H. Lee,
Published: 27 September 2017
Journal: The Analyst
The Analyst, Volume 142, pp 4317-4321; https://doi.org/10.1039/c7an01465a

Abstract:
A simple, and yet robust, high pass filter is designed to remove non-linear background drift in fast scan cyclic voltammetry.
Published: 26 September 2017
Journal: The Analyst
The Analyst, Volume 142, pp 4161-4172; https://doi.org/10.1039/c7an01019b

Abstract:
NMR offers tremendous advantages in the analyses of molecular complexity. The “big-data” are produced during the acquisition of fingerprints that must be stored and shared for posterior analysis and verifications.
Dazhi Yao, Wenqi Zhao, ,
Published: 26 September 2017
Journal: The Analyst
The Analyst, Volume 142, pp 4215-4220; https://doi.org/10.1039/c7an01295k

Abstract:
Developing a sensitive and accurate method for Furin activity is still the bottleneck for understanding the role played by Furin in cell-surface systems and even in Alzheimer's disease.
Published: 1 January 2017
Journal: The Analyst
The Analyst, Volume 142, pp 3526-3526; https://doi.org/10.1039/c7an90074k

Abstract:
A graphical abstract is available for this content
Published: 1 January 2017
Journal: The Analyst
The Analyst, Volume 142, pp 3525-3525; https://doi.org/10.1039/c7an90073b

Abstract:
A graphical abstract is available for this content
Published: 1 January 2017
Journal: The Analyst
The Analyst, Volume 142, pp 3759-3760; https://doi.org/10.1039/c7an90076g

Abstract:
A graphical abstract is available for this content
Published: 6 November 2012
Journal: The Analyst
The Analyst, Volume 138, pp 501-508; https://doi.org/10.1039/c2an36390a

Abstract:
Hardwood and softwood lignins obtained from industrial sulphite and kraft and laboratory oxygen-organosolv pulping processes were employed in co-polymerization with tolylene 2,4-diisocyanate terminated poly(propylene glycol). The obtained lignin-based polyurethanes were doped with 0.72 w/w% of multiwall carbon nanotubes (MWCNTs) with the aim of increasing their electrical conductivity to the levels suitable for sensor applications. Effects of the polymer doping with MWCNTs were assessed using electrical impedance (EIS) and UV-Resonance Raman (UV-RR) spectroscopy. Potentiometric sensors were prepared by drop casting of liquid polymer on the surface of carbon glass or platinum electrodes. Lignin-based sensors displayed a very low or no sensitivity to all alkali, alkali-earth and transition metal cations ions except Cr(VI) at pH 2. Response to Cr(VI) values of 39, 50 and 53 mV pX−1 for the sensors based on kraft, organosolv and lignosulphonate lignins, respectively, were observed. Redox sensitivity values close to the theoretical values of 20 and 21 mV pX−1 for organosolv and lignosulphonate based sensors respectively were detected in the Cr(III)/Cr(VI) solutions while a very low response was observed in the solutions containing Fe(CN)63−/4−. Conducting composite lignin-based polyurethanes doped with MWCNTs were suggested as being promising materials for Cr(VI)-sensitive potentiometric sensors.
Xiaoping Jia, Minli Xu, Yuzhi Wang, Dan Ran, Shan Yang, Min Zhang
Published: 6 November 2012
Journal: The Analyst
The Analyst, Volume 138, pp 651-658; https://doi.org/10.1039/c2an36313e

Abstract:
Surface molecular imprinting, especially on the surface of silica-modified magnetic nanoparticles, has been proposed as a promising strategy for protein recognition and separation. Inspired by the self-polymerization of dopamine, we synthesized a polydopamine-based molecular imprinted film coating on silica–Fe3O4 nanoparticles for recognition and separation of bovine hemoglobin (BHb). Magnetic molecularly imprinted nanoparticles (about 860 nm) possess a core–shell structure. Magnetic molecularly imprinted nanoparticles (MMIP) show a relatively high adsorption capacity (4.65 ± 0.38 mg g−1) and excellent selectivity towards BHb with a separation factor of 2.19. MMIP with high saturation magnetization (10.33 emu g−1) makes it easy to separate the target protein from solution by an external magnetic field. After three continuous adsorption and elution processes, the adsorption capacity of MMIP remained at 4.30 mg g−1. Our results suggest that MMIPs are suitable for the removal of high abundance of protein and the enrichment of low abundance of protein in proteomics.
Xiaocui Lu, Xiao Dong, Keying Zhang, Xiaowei Han, Xian Fang, Yuzhong Zhang
Published: 6 November 2012
Journal: The Analyst
The Analyst, Volume 138, pp 642-650; https://doi.org/10.1039/c2an36099c

Abstract:
In this study, we designed a fluorescence resonance energy transfer system containing gold nanorods (AuNRs) and fluorescein (FAM) for the detection of hepatitis B virus DNA sequences. AuNRs were synthesized according to the seed-mediated surfactant-directed approach, and the surface of the AuNRs was wrapped with a thin layer of cetyltrimethylammonium bromide (CTAB), resulting in the AuNRs being positively charged. When FAM-tagged single-stranded DNA (FAM-ssDNA) was added into the AuNRs suspension, it was adsorbed onto the surface of the positively charged AuNRs and formed a FAM-ssDNA–CTAB–AuNRs ternary complex, the resulting structure led to a fluorescence resonance energy transfer (FRET) process from FAM to AuNRs and the fluorescence intensity of FAM was consequently quenched. When complementary target DNA was added to the FAM-ssDNA–CTAB–AuNRs complex solution, a further decrease in fluorescence intensity was observed because of an increased FRET efficiency. Under optimal conditions, the decline of the fluorescence intensity of FAM (ΔF) was linear with the concentration of the complementary DNA from 0.045 to 6.0 nmol L−1 and the detection limit was as low as 15 pmol L−1 (signal/noise ratio of 3). When this fluorescent DNA sensor was used to detect the polymerase chain reaction product of hepatitis B virus gene extracted from a positive real sample, a positive response was obtained. Impressively, the biosensor exhibits good selectivity, even for single-mismatched DNA detection.
, , Jing-Fang Niu, Juan Zhao, Yuan-Na Li, ,
Published: 6 November 2012
Journal: The Analyst
The Analyst, Volume 138, pp 627-634; https://doi.org/10.1039/c2an35931f

Abstract:
The alignment of chromatographic peaks and deconvolution of overlapped peaks still remain challenges in the field of complex sample analysis. In this paper, we highlight a strategy that employs a new time shift alignment method derived from the well-known Rank Minimization method for aligning chromatographic peak shifts among samples and then uses trilinear decomposition methodology to interpret the overlapped chromatographic peaks in order to quantify analytes of interest. The performance of this novel strategy for chromatographic data analysis was evaluated using simulated chromatographic data as well as real chromatographic data. The results indicate that the new time shift alignment method can accurately correct time shifts in test samples even in the presence of unexpected interferences, and thus the low-rank trilinearity of the same analyte can be obtained, which will be helpful for trilinear decomposition to achieve the second-order advantage. Moreover, the results showed that this new alignment method is more automated in comparison with the Rank Minimization method and will be suitable for the alignment of the time shifts of analytes that are completely overlapped by coeluted interferences.
, Fuyi Zhou, Songjie Chen, Yao Yao, Jing Wu, Dengyang Yin, ,
Published: 27 September 2017
Journal: The Analyst
The Analyst, Volume 142, pp 4308-4316; https://doi.org/10.1039/c7an01434a

Abstract:
A novel electrochemical homogeneous immunosensor strategy was developed based on proximity hybridization that regulated the RCA.
Haihan Chen, Vicki H. Grassian, Laxmikant V. Saraf,
Published: 8 November 2012
Journal: The Analyst
The Analyst, Volume 138, pp 451-460; https://doi.org/10.1039/c2an36318f

Abstract:
Airborne fly ash from coal combustion may represent a source of bioavailable iron (Fe) in the open ocean. However, few studies have focused on Fe speciation and distribution in coal fly ash. In this study, chemical imaging of fly ash has been performed using a dual-beam focused ion beam/scanning electron microscope (FIB/SEM) system for a better understanding of how simulated atmospheric processing can modify the morphology, chemical composition and element distribution within individual particles. A novel approach has been applied for cross-sectioning fly ash particles with the FIB in order to explore element distribution within the interior of individual particles. Our results indicate that simulated atmospheric processing can cause disintegration of aluminosilicate glass, a dominant material in fly ash particles. Fe present in the inner core of fly ash spheres within the aluminosilicate phase is more easily mobilized compared with Fe oxides present as surface aggregates on the exterior of fly ash spheres. Fe dissolution depends strongly on Fe speciation in fly ash particles. The approach for preparation of a cross-sectioned specimen described here opens up new opportunities for particle microanalysis, particularly with respect to inorganic refractive materials like fly ash and mineral dust.
Published: 17 October 2017
Journal: The Analyst
The Analyst, Volume 142, pp 4299-4307; https://doi.org/10.1039/c7an01084b

Abstract:
The demand for electrochemical sensors with high sensitivity and reliability, fast response, and excellent selectivity has stimulated intensive research on developing highly active nanomaterials. In this work, freestanding 3D/Co3O4 thorn-like and wire-like (nanowires) nanostructures are directly grown on a flexible carbon fiber paper (CFP) substrate by a single-step hydrothermal process without using surfactants or templates. The 3D/Co3O4 thorn-like nanostructures show higher electrochemical activity than wire-like because of their high conductivity, large specific surface areas, and mesopores on their surface. The characterization of 3D/Co3O4 nanostructures is performed by using high resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction analysis (XRD), and electrochemical methods. The 3D/Co3O4 thorn-like nanostructures displayed non-enzymatic higher catalytic activity towards the electrochemical detection of glucose, compared to the 3D/Co3O4 wire-like morphology. The 3D/Co3O4 thorn-like nanostructures show a wide linear range response of glucose concentration ranging from 1 to 1000 μM with a detection limit of 0.046 μM (S/N = 3). The 3D/Co3O4 thorn-like nanostructure-modified CFP electrode selectively detects glucose in the presence of 100-fold excess of interfering compounds. The 3D/Co3O4 thorn-like nanostructure-modified CFP electrode is tested with human blood serum samples and validated with commercial glucose sensors. The newly developed sensor material shows potential for glucose monitoring in clinical and food samples.
, , Pamela Espindola, Christoph Boehm, Thorsten Brueckner, Juergen Spinke, Moritz Marcinowski, Thomas Keller, Armin Tgetgel, Nicolas Herbert, et al.
Published: 22 September 2017
Journal: The Analyst
The Analyst, Volume 142, pp 4206-4214; https://doi.org/10.1039/c7an00547d

Abstract:
A fully integrated cartridge for highly sensitive immunochemical analysis of cardiac markers with new microfluidic functionalities is presented.
Xi Wu, Tian Li, Guangyu Tao, Ruoyun Lin, Xiaojing Pei, Feng Liu,
Published: 26 September 2017
Journal: The Analyst
The Analyst, Volume 142, pp 4201-4205; https://doi.org/10.1039/c7an01495c

Abstract:
We develop a universal and enzyme-free magnetic bead-based sandwich-format immunoassay platform for biomarker detection by combining secondary antibody functionalized AuNPs and automatic AuNP counting.
XueQian Chen, Wenying Gui, Hua Liu,
Published: 22 September 2017
Journal: The Analyst
The Analyst, Volume 142, pp 4142-4149; https://doi.org/10.1039/c7an01250k

Abstract:
A novel ECL sensing system was developed for lysophosphatidic acid detection based on AGM-CuInZnS QDs and GNs.
, Chong Su, Tianming Ren, Xiangjun Meng, Meiyun Shi, J. Paul Fawcett, , Wei Hu,
Published: 6 October 2017
Journal: The Analyst
The Analyst, Volume 142, pp 4279-4288; https://doi.org/10.1039/c7an00470b

Abstract:
The covalent attachment of polyethylene glycol (PEG) to therapeutic compounds (known as PEGylation) is one of the most promising techniques to improve the biological efficacy of small molecular weight drugs. After administration, PEGylated prodrugs can be metabolized into pharmacologically active compounds so that PEGylated drug, free drug and released PEG are present simultaneously in the body. Understanding the pharmacokinetic behavior of these three compounds is needed to guide the development of pegylated theranostic agents. However, PEGs are polydisperse molecules with a wide range of molecular weights, so that the simultaneous quantitation of PEGs and PEGylated molecules in biological matrices is very challenging. This article reports the application of a data-independent acquisition method (MSAll) based on liquid chromatography electrospray ionization quadrupole time-of-flight mass spectrometry (LC-q-q-TOF-MS) in the positive ion mode to the simultaneous determination of methoxyPEG2000-doxorubicin (mPEG2K-Dox) and its breakdown products in rat blood. Using the MSAll technique, precursor ions of all molecules are generated in q1, fragmented to product ions in q2 (collision cell), and subjected to TOF separation before precursor and product ions are recorded using low and high collision energies (CE) respectively in different experiments for a single sample injection. In this study, dissociation in q2 generated a series of high resolution PEG-related product ions at m/z 89.0611, 133.0869, 177.1102, 221.1366, 265.1622, 309.1878, and 353.2108 corresponding to fragments containing various numbers of ethylene oxide subunits, Dox-related product ions at m/z 321.0838 and 361.0785, and an mPEG2K-Dox specific product ion at m/z 365.0735. Detection of mPEGs and mPEG2K-Dox was based on high resolution extracted ions of mPEG and the specific compound. The method was successfully applied to a pharmacokinetic study of doxorubicin, mPEG2K (methylated polyethylene glycol 2K), and mPEG2K-doxorubicin in rats after a single intravenous injection of mPEG2K-doxorubicin. To the best of our knowledge, this is the first assay that simultaneously determines mPEG, Dox, and mPEG2K-Dox in a biological matrix. We believe the MSAll technique as applied in this study can be potentially extended to the determination of other PEGylated small molecules or polymeric compounds.
, Raquel Sero Llor, Alan K. Jarmusch, Clint M. Alfaro, , Eyas M. Hattab,
Published: 27 September 2017
Journal: The Analyst
The Analyst, Volume 142, pp 4058-4066; https://doi.org/10.1039/c7an01334e

Abstract:
Touch spray mass spectrometry using medical swabs is an ambient ionization technique (ionization of unprocessed sample in the open air) that has potential intraoperative application in quickly identifying the disease state of tissue and in better characterizing the resection margin. To explore this potential, we studied 29 human brain tumor specimens and obtained evidence that this technique can provide diagnostic molecular information that is relevant to brain cancer. Touch spray using medical swabs involves the physical sampling of tissue using a medical swab on a spatial scale of a few mm2 with subsequent ionization occurring directly from the swab tip upon addition of solvent and application of a high voltage. Using a tertiary mixture of acetonitrile, N,N-dimethylformamide, and ethanol, membrane-derived phospholipids and oncometabolites are extracted from the tissue, incorporated into the sprayed microdroplets, vacuumed into the mass spectrometer, and characterized in the resulting mass spectra. The tumor cell load was assessed from the complex phospholipid pattern in the mass spectra and also separately by measurement of N-acetylaspartate. Mutation status of the isocitrate dehydrogenase gene was determined via detection of the oncometabolite 2-hydroxyglutarate. The lack of sample pretreatment makes touch spray mass spectrometry using medical swabs a feasible intraoperative strategy for rapid surgical assessment.
Christopher G. Bell, Parinya Seelanan,
Published: 26 September 2017
Journal: The Analyst
The Analyst, Volume 142, pp 4048-4057; https://doi.org/10.1039/c7an01450c

Abstract:
A novel analysis of generator–collector devices is presented and applied to electrolytic acid–base titration.
Published: 29 September 2017
Journal: The Analyst
The Analyst, Volume 142, pp 4099-4105; https://doi.org/10.1039/c7an00898h

Abstract:
Imaging of the in situ production of nitric oxide following phagocytosis of Escherichia coli bacteria using a NO nanobiosensor.
Published: 7 September 2017
Journal: The Analyst
The Analyst, Volume 142, pp 3822-3829; https://doi.org/10.1039/c7an01308f

Abstract:
The accuracy of low-level hydrogen measurements with prompt gamma-ray activation analysis (PGAA) depends on identifying and accounting for all background H signals, including interfering signals, which are investigated and quantified in this work.
, Yixin Qu, Qipeng Yuan, , Zhenxia Du, Dazhou Chen, Choon Wong
Published: 26 November 2012
Journal: The Analyst
The Analyst, Volume 138, pp 659-665; https://doi.org/10.1039/c2an36022e

Abstract:
The electrospray ionization (ESI) is a complex process and there has been a long debate regarding the gas-phase effect on ion generation in the process. In this paper we investigated the effect of liquid chromatographic mobile phase additives (formic acid, aqueous ammonia and their combination) on the ESI signal intensities for a wide variety of compounds. The addition of a trace amount of aqueous ammonia to the common formic acid–methanol mobile phase significantly enhances the ESI signals of protonated molecules and suppresses the formation of sodium adduct ions. This effect is well observed for the compounds containing the –N–CO group but not for those without N or O atoms. The ESI signal intensity of deprotonated molecules increases with increase in pH of the mobile phase for neutral compounds, such as substituted urea, whereas this trend is not observed for acidic compounds such as phenoxy acids. The mechanistic analysis regarding liquid- and gas-phase protonation and deprotonation is discussed.
, Marianne Odlyha, Francesca Di Girolamo, , Terje Grøntoft,
Published: 31 October 2012
Journal: The Analyst
The Analyst, Volume 138, pp 487-500; https://doi.org/10.1039/c2an36259g

Abstract:
This paper investigates the effects of inorganic (NO2 and O3) and volatile organic acid (acetic acid) pollutants on the degradation of dammar varnish in museum environments. Model paint varnish samples based on dammar resin were investigated by Gas Chromatography Mass Spectrometry (GC-MS), Dynamic Mechanical Analysis (DMA) and Atomic Force Microscopy (AFM). Dammar is a natural triterpenoid resin, commonly used as a paint varnish. Samples were subjected to accelerated ageing by different levels of pollutants (NO2 and O3 and acetic acid) over a range of relative humidities (RH) and then analysed. The results revealed that as the dose of the pollutant was increased, so did the degree of oxidation and cross-linking of the resin. Most interestingly, it was shown for the first time that exposure to acetic acid vapour resulted in the production of an oxidised and cross-linked resin, comparable to the resin obtained under exposure to NO2 and O3. These conclusions were supported by the analyses of model varnishes exposed for about two years in selected museum environments, where the levels of pollutants had been previously measured. Exposures were performed both within and outside the selected microclimate frames for paintings. Results showed that varnishes placed within the microclimate frames were not always better preserved than those exposed outside the frames. For some sites, the results highlighted the protective effects of the frames from outdoor generated pollutants, such as NO2 and O3. For other sites, the results showed that the microclimate frames acted as traps for the volatile organic acids emitted by the wooden components of the mc-frames, which damaged the varnish.
Published: 31 October 2012
Journal: The Analyst
The Analyst, Volume 138, pp 603-610; https://doi.org/10.1039/c2an36222h

Abstract:
Raman imaging was used to illustrate heterogeneity of a single endothelial cell and the vascular wall sample. The spectral analysis allowed for exploring the complexity of the studied systems in three dimensions and defining the size, volume, shape and biochemical composition of cellular organelles. The ability to construct the 3D maps by a method that does not disrupt the spatial integrity of the cell provided a unique insight into biochemical architecture and cellular processes of endothelium and vascular wall. 3D Raman imaging may be considered as a new trend in analytical spectroscopy to be applied in biomedical research. This method has a potential to be used for medical imaging and diagnostic purposes together with other, already established, imaging techniques.
, Willem Norde, Aart van Amerongen
Published: 1 January 2013
Journal: The Analyst
The Analyst, Volume 138, pp 518-524; https://doi.org/10.1039/c2an36104c

Abstract:
Non-contact inkjet printing technology is one of the most promising tools for producing microarrays. The quality of the microarray depends on the type of the substrate used for printing biomolecules. Various porous and non-porous substrates have been used in the past, but due to low production cost and easy availability, non-porous substrates like glass and plastic are preferred over porous substrates. On these non-porous substrates, obtaining spot uniformity and a high signal to noise ratio is a big challenge. In our research work, we have modified pristine glass slides using various silanes to produce a range of hydrophobic glass substrates. The hydrophobicities of the slides expressed in the contact angle (θ) of a sessile drop of water were 49°, 61°, 75°, 88° and 103°. Using a non-contact inkjet printer, microarrays of biotinylated biomolecules (BSA and IgG) were produced on these modified glass substrates, pristine (untreated) glass and also on HTA polystyrene slides. The uniformity of the spots, reflecting the distribution of the biomolecules in the spots, was analyzed and compared using confocal laser scanning microscopy (CLSM). The quality of the spots was superior on the glass slide with a contact angle of 75°. We also investigated the influence of the hydrophobicity of the substrate on a two-step, real diagnostic antibody assay. This nucleic acid microarray immunoassay (NAMIA) for the detection of Staphylococcus aureus showed that on highly hydrophilic (θ< 10°) and hydrophobic substrates (θ > 100°) the assay signal was low, whereas an excellent signal was obtained on the substrates with intermediate contact angles, θ 61° and θ 75°, respectively.
Published: 31 October 2012
Journal: The Analyst
The Analyst, Volume 138, pp 480-486; https://doi.org/10.1039/c2an35972c

Abstract:
Here, we describe a highly sensitive method that allows for the correct quantification of inhibition effect with a higher degree of accuracy directly at the molecular level. The protocol involves two stages, namely serological virus titration in comparison with the same procedure for virus–effector mixture. Owing to the robustness of the analysis this assay can be performed on crude cellular and plant extracts, and therefore it may be suitable for the routine analysis of clinical samples, or in the field. The efficiency of the approach to the quantification of the inhibition effect of polysaccharide glucuronoxylomannan (GXM) on the infection efficiency of the tobacco mosaic virus (TMV) was investigated using advanced serological approaches based on label-free surface plasmon resonance technique. It was shown that GXM drastically decreases the efficiency of TMV infection by blocking up to 70% of the virus shell. The obtained results are in conformity with the method of indicator plant infection.
Leonid T. Cherney,
Published: 5 November 2012
Journal: The Analyst
The Analyst, Volume 138, pp 553-558; https://doi.org/10.1039/c2an36296a

Abstract:
To better understand the regulatory roles of miRNA in biological functions and to use miRNA as molecular markers of diseases, we need to accurately measure amounts of multiple miRNAs in biological samples. Direct quantitative analysis of multiple miRNAs (DQAMmiR) has been recently developed by using a classical hybridization approach where miRNAs are hybridized with fluorescently labeled complementary DNA probes taken in excess, and the amounts of the hybrids and the unreacted probes are measured to calculate the amount of miRNAs. Capillary electrophoresis was used as an instrumental platform for analysis. The problem of separating the unreacted probes from the hybrids was solved by adding SSB to the run buffer. A more difficult problem of separating hybrids from each other was solved by attaching different drag tags to the probes. Biotin and a hairpin-forming extension on the probe were used as two drag tags in the proof-of-principle work. Making DQAMmiR a generic approach requires a generic solution for drag tags. Peptides have been suggested as drag tags for long oligonucleotides in DNA sequencing by electrophoresis. Here we theoretically consider short peptides of different lengths as drag tags for DQAMmiR. We find analytical equations that allow us to estimate mobilities of RNA–DNA hybrids with peptide drag tags of different lengths. Our calculations suggest that the mobility shifts required for DQAMmiR can be achieved with the length of peptide chains in the ranges of 5–20 residues for five miRNAs and 2–47 residues for nine miRNAs. Peptides of these lengths can be feasibly synthesized with good yield and purity. The results of this theoretical study will guide the design and production of hybridization probes for DQAMmiR.
, Yujian He
Published: 1 January 2013
Journal: The Analyst
The Analyst, Volume 138, pp 539-545; https://doi.org/10.1039/c2an36145k

Abstract:
The polymerase chain reaction (PCR) has become an indispensable technique in molecular biology, however, it suffers from low efficiency and specificity problems. Developing suitable additives to effectively avoid nonspecific PCR reactions and explore the mechanism for PCR enhancing is a significant challenge. In this paper, we report three different modified gold nanoparticles (AuNPs) with different surface charge polarities and poly (diallyl dimethylammonium) chloride (PDDA) for use as novel PCR enhancers to improve the efficiency and specificity. These AuNPs included the positively charged PDDA protected AuNPs (PDDA-AuNPs), the neutral PDDA-AuNPs modified with excess chloride ion (PDDA.C-AuNPs), and the negatively charged sodium citrate (Na3Ct) protected AuNPs (Na3Ct-AuNPs). Our data clearly suggests that the positively charged PDDA-AuNPs with an optimum concentration as low as 1.54 pM could significantly enhance the specificity and efficiency of PCR, however, the optimum concentration of the negatively charged Na3Ct-AuNPs (2.02 nM) was more than 3 orders of magnitude higher than that of positively charged PDDA-AuNPs. The PCR specificity and efficiency are also improved by the neutral PDDA.C-AuNPs with an optimum concentration, much more than that of the PDDA-AuNPs. This suggests that there should be an electrostatic interaction between the positively charged PDDA-AuNPs and the negatively charged PCR components, and the surface charge polarities of PDDA-AuNPs may play an important role in improving the PCR specificity and efficiency.
Correction
Sian Sloan-Dennison, Stacey Laing, Neil C. Shand, ,
Published: 18 September 2017
Journal: The Analyst
The Analyst, Volume 142, pp 3993-3993; https://doi.org/10.1039/c7an90067h

Abstract:
Correction for ‘A novel nanozyme assay utilising the catalytic activity of silver nanoparticles and SERRS’ by Sian Sloan-Dennison et al., Analyst, 2017, 142, 2484–2490.
Mohammed Fahad Hasan,
Published: 15 September 2017
Journal: The Analyst
The Analyst, Volume 142, pp 4089-4098; https://doi.org/10.1039/c7an01054k

Abstract:
Marine phytoplankton acts as a considerable sink of atmospheric CO2as it sequesters large quantities of this greenhouse gas for biomass production.
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