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Shihua Yu, Zhigang Liu, Hongwei Li, Jianpo Zhang, Xin-Xin Yuan, Xiangyu Jia, Yuqing Wu
Surface enhanced Raman scattering (SERS) is an ultra-sensitive spectroscopy technique, which can provide rich structural information for a great number of molecules, while solid phase micro-extraction (SPME) is an efficient method for sample pretreatment in analytical chemistry, particularly in a micro-system. In the present report, a silver-loaded and graphene-based magnetic composite (Fe3O4@GO@Ag) was fabricated for use as both a SERS-active substrate and SPME material. The π-π stacking and fluorescence quenching abilities of GO make the composite a perfect candidate for SERS in analyzing real-world samples...
January 18, 2018: Analyst
S A N Gowers, K Hamaoui, P Cunnea, S Anastasova, V F Curto, P Vadgama, G-Z Yang, V Papalois, E M Drakakis, C Fotopoulou, S G Weber, M G Boutelle
This paper presents the use of tubing to store clinical microdialysis samples for delayed analysis with high temporal resolution, offering an alternative to traditional discrete offline microdialysis sampling. Samples stored in this way were found to be stable for up to 72 days at -80 °C. Examples of how this methodology can be applied to glucose and lactate measurement in a wide range of in vivo monitoring experiments are presented. This paper presents a general model, which allows for an informed choice of tubing parameters for a given storage time and flow rate avoiding high back pressure, which would otherwise cause the microdialysis probe to leak, while maximising temporal resolution...
January 16, 2018: Analyst
Kamonwad Ngamchuea, Korbua Chaisiwamongkhol, Christopher Batchelor-McAuley, Richard G Compton
Correction for 'Chemical analysis in saliva and the search for salivary biomarkers - a tutorial review' by Kamonwad Ngamchuea, et al., Analyst, 2018, 143, 81-99.
January 15, 2018: Analyst
G Lippens, E Cahoreau, P Millard, C Charlier, J Lopez, X Hanoulle, J C Portais
In-cell NMR of macromolecules has gained momentum over the last ten years as an approach that might bridge the branches of cell biology and structural biology. In this review, we put it in the context of earlier efforts that aimed to characterize by NMR the cellular environment of live cells and their intracellular metabolites. Although technical aspects distinguish these earlier in vivo NMR studies and the more recent in cell NMR efforts to characterize macromolecules in a cellular environment, we believe that both share major concerns ranging from sensitivity and line broadening to cell viability...
January 15, 2018: Analyst
M Toma, S Izumi, K Tawa
A rapid and sensitive detection of a cancer marker, neuron specific enolase (NSE), is demonstrated by using a disposable silver plasmonic chip functionalized with a mussel-inspired polydopamine (PDA) coating. A plasmonic chip consisting of a diffraction grating coated with a silver thin film is used for the excitation of propagating surface plasmon resonance through a rear-side grating coupling method. Simple and quick bio-functionalization of the sensor surface is performed by PDA coating which requires 20 min for deposition, and allows direct attachment of the capture antibody without using any coupling agents...
January 12, 2018: Analyst
Yuji Iwaoka, Kohei Nishino, Takahiro Ishikawa, Hideyuki Ito, Yoshihiro Sawa, Akihiro Tai
l-Ascorbic acid (AA) has diverse physiological functions, but little is known about the functional mechanisms of AA. In this study, we synthesized two types of affinity resin on which AA is immobilized in a stable form to identify new AA-targeted proteins, which can provide important clues for elucidating unknown functional mechanisms of AA. To our knowledge, an affinity resin on which AA as a ligand is immobilized has not been prepared, because AA is very unstable and rapidly degraded in an aqueous solution...
January 12, 2018: Analyst
Carlton F O Hoy, Keiichiro Kushiro, Madoka Takai
This study investigated the fabrication and proof of concept design demonstrating rapid and highly sensitive antigen capture utilizing electrospun polystyrene (PS) microfiber mat substrates paired with vacuum pump pressurization to induce bulk flow. In comparison with conventional flat PS surfaces used for immunoassay purposes, this system optimizes the increased surface area of the electrospun polystyrene (ESPS) fiber mat substrates and the accelerated propagation of the antigen through the detection platform by using a vacuum pump to enable efficient and rapid antigen capture...
January 12, 2018: Analyst
Lin Liu, Hua Zhang, Daqian Song, Zhenxin Wang
We report a new fluorescence resonance energy transfer (FRET) sensing platform for the sensitive detection of caspase-3 activity in vitro and in cells using NaGdF4:Yb3+,Er3+@NaGdF4 upconversion nanoparticles (UCNPs) as the energy donor and Rhodamine B (RB) as the energy acceptor. The phosphorylated RB-modified peptide containing a caspase-3 cleavage site and cell-penetrating peptide (CPP) motif (sequence, (RB)-DEVDGGS(p)GCGT(p)GRKKRRQRRRPQ) is immobilized on the UCNP surface via the strong coordination interaction between Gd3+ ions with phosphate...
January 12, 2018: Analyst
Naifu Jin, Kirk T Semple, Longfei Jiang, Chunling Luo, Dayi Zhang, Francis L Martin
Exposure to environmental insults generally occurs at low levels, making it challenging to measure bacterial responses to such interactions. Additionally, microbial behaviour and phenotype varies in differing bacterial types or growth phases, likely giving rise to growth- or species-specific responses to environmental stimuli. The present study applied a spectrochemical tool, infrared (IR) spectral interrogation coupled with multivariate analysis, to investigate the growth- and species-specific responses of two bacterial strains, Gram-negative Pseudomonas fluorescens and Gram-positive Mycobacterium vanbaalenii, to low concentrations of tetracycline, nanoparticulate silver (AgNP) or mixtures thereof...
January 12, 2018: Analyst
Mengzhao Zhang, Taohua Leng, Yongjia Shen, Chengyun Wang
Although widely used in organic synthesis, pharmaceuticals and agrochemicals, thiophenol has brought about a series of ecological problems due to its high toxicity. Therefore, the development of efficient methods to discriminate thiophenols from aliphatic thiols is of great importance. In this work, a new reaction-based turn-on red fluorescence probe for the detection of thiophenols has been developed for the first time by employing dicyanomethylene-4H-pyran (DCM) as a fluorescence reporter and 2,4-dinitrobenzene-sulfonate (DNBS) as a recognition unit...
January 11, 2018: Analyst
S Braziel, K Sullivan, S Lee
Using confocal Raman microspectroscopy, we derive parameters for bilayer water transport across an isolated nanoliter aqueous droplet pair. For a bilayer formed with two osmotically imbalanced and adherent nanoliter aqueous droplets in a surrounding oil solvent, a droplet interface bilayer (DIB), the water permeability coefficient across the lipid bilayer was determined from monitoring the Raman scattering from the C[triple bond, length as m-dash]N stretching mode of K3Fe(CN)6 as a measure of water uptake into the swelling droplet of a DIB pair...
January 11, 2018: Analyst
Milad Nazari, Mark T Bokhart, Philip L Loziuk, David C Muddiman
A quantitative mass spectrometry imaging (QMSI) method for absolute quantification of glutathione (GSH) in healthy and cancerous hen ovarian tissues using infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) is presented. Using this technique, the ion abundance of GSH was normalized to that of a structural analogue, which was sprayed on the slide prior to mounting the tissue sections. This normalization strategy significantly improved the voxel-to-voxel variability; the variability is attributed to the overall ionization process...
January 11, 2018: Analyst
Leilei Shi, Yufeng Liu, Qian Wang, Tiankuo Wang, Yubin Ding, Yi Cao, Zhe Li, Hui Wei
By combining leucine (Leu) and tetraphenylethene (TPE), a pH-sensitive aggregation induced emission (AIE) probe TPE-Leu was developed. The aliphatic amine in TPE-Leu was more easily protonated under acidic conditions, which made TPE-Leu more water soluble. Therefore, the protonated AIE probe showed weak fluorescence under acidic conditions. When the pH was changed to basic conditions, it showed strong fluorescence due to the hydrophobic nature of TPE-Leu. We demonstrated that the probe showed high selectivity toward pH changes with the coexistence of other potential species such as metal ions, redox agents, and biomolecules...
January 11, 2018: Analyst
Arnab Mukherjee, Vincent A Hackley
Cellulose nanocrystals (CNCs) are renewable, naturally derived polymeric nanomaterials receiving substantial attention for a wide range of potential applications. The recent availability of high quality reference materials will facilitate the development and validation of measurement methods needed to advance the scientific and commercial use of CNCs. In the present study, we demonstrate an optimized method to fractionate CNCs with narrow size dispersion based on asymmetrical-flow field-flow fractionation (AF4) coupled with on-line multi-angle light scattering (MALS), dynamic light scattering (DLS), and differential refractometry (dRI)...
January 11, 2018: Analyst
Tingting Hou, Yuanfu Zhang, Tao Wu, Meifeng Wang, Yinghong Zhang, Rui Li, Lei Wang, Qingwang Xue, Shuhao Wang
A simple, label-free colorimetric method for the determination of fibrinogen (Fib) in plasma is presented. In this work, it was observed that Fib interacted with hemin to form a hemin-Fib composite. Because Fib prevented hemin from the formation of m-oxo-dimers, the hemin-Fib composite possesses excellent peroxidase-like activity. Importantly, the peroxidase-like activity of Fib-hemin increased with the increase in the Fib. This allows us to utilize the H2O2-ABTS colorimetric system for the quantitative analysis of Fib...
January 11, 2018: Analyst
Rui Mao, Lifei Qi, Jianjun Li, Ming Sun, Zhuo Wang, Yuguang Du
A novel nucleic acid isothermal amplification method with high specificity, efficiency and rapidity was developed. The principle of primer design was achieved by slight modification of PCR primers. Acceleration probes were also explored. The newly developed method is of great potential for point of care diagnostics.
January 10, 2018: Analyst
Yueyue Yao, Xiuzhong Wang, Wenna Duan, Feng Li
A label-free, versatile and low-background chemiluminescence (CL) sensing strategy based on gold nanocluster catalysis combined with the separation of magnetic beads (MBs) was developed. Kanamycin was selected as the target analyte to exhibit the analytical performance of this platform. Two single-stranded DNA (named DNA1 and DNA2) are ingeniously designed. DNA1, containing an aptamer sequence of the targets, was firstly immobilized on the MBs which were modified with many amino groups by amidation reaction...
January 9, 2018: Analyst
Sweta Binod Kumar, Hardik Trivedi, Narshibhai Rameshbhai Baraiya, Soumya Haldar
The prime requirement for marine water studies is a competent sampling device that can collect water samples perfectly without any contamination to avoid false analysis. The present study demonstrates the design and operation of a cost-effective novel water sampler, which collects contamination-free water from any desired depths of seawater. The sampler is also fitted with polyvinylidene fluoride (PVDF) membranes with improved property for concentration of diversified bacteria. To test the efficiency of the designed sampler under field conditions, the differential depth water sampler (DDWS) was deployed at two coastal sampling stations to collect water samples from various depths...
January 8, 2018: Analyst
B M Tran, N N Nam, S J Son, N Y Lee
Nanoporous anodic aluminum oxide internalized with gold nanoparticles was utilized as an integrated platform miniaturized for consecutively performing on-chip PCR and downstream detection of the amplified product of a 183 bp eaeA gene fragment from Escherichia coli O157:H7 using surface-enhanced Raman scattering (SERS).
January 5, 2018: Analyst
Guanbo Wang, Pavel V Bondarenko, Igor A Kaltashov
Heat-induced conformational transitions are frequently used to probe the free energy landscapes of proteins. However, the extraction of information from thermal denaturation profiles pertaining to non-native protein conformations remains challenging due to their transient nature and significant conformational heterogeneity. Previously we developed a temperature-controlled electrospray ionization (ESI) source that allowed unfolding and association of biopolymers to be monitored by mass spectrometry (MS) in real time as a function of temperature...
January 5, 2018: Analyst
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