Childersmerritt3745

Optical detection setup utilizing light emitting diodes (LEDs), 50 nL L-shaped silica capillary detection cell (L-cell), and low-cost CCD spectrometer is described in this work. Experimental configuration can be equipped with two different LEDs for absorbance measurement and other two LEDs for fluorescence excitation. This setup is capable of simultaneous multi-wavelength monitoring of absorbance and fluorescence when light produced by the individual LEDs and light emitted by the fluorescent analytes is resolved in the spectrum outputted by the CCD spectrometer. Effective optical path of the 0.25 μm I. D. L-cell is 1 mm. Absorbance baseline noise is 1 mAU due to use of low-cost and relatively noisy CCD spectrometer and LED drivers. Nevertheless, the setup can detect adenosine 5'-monophosphate down to micromolar concentration. Performance of fluorescence monitoring allows detection of 5·10-10 M fluorescein when 23 mW 470 nm LED is used for excitation. The dynamic range of absorbance and fluorescence measurement is 8671 and 16221, respectively. Separation of test mixture (alkylbenzenes and polyaromatic hydrocarbons) demonstrate the effective use of the detector for simultaneous absorbance and fluorescence detection with 0.2 × 150 mm packed capillary column. The benefits of the setup are relative simplicity, compact design and the fact that it can be operated without any optical filters, slits, and extremely precise positioning of the optical elements. One of the most widely used approaches to characterize transmembrane ion transport through nanoscale synthetic or biological channels is a straightforward, liposome-based assay that monitors changes in ionic flux across the vesicle membrane using pH- or ion-sensitive dyes. However, failure to account for the precise experimental conditions, in particular the complete ionic composition on either side of the membrane and the inherent permeability of ions through the lipid bilayer itself, can prevent quantifications and lead to fundamentally incorrect conclusions. Here we present a quantitative model for this assay based on the Goldman-Hodgkin-Katz flux theory, which enables accurate measurements and identification of optimal conditions for the determination of ion channel permeability and selectivity. Based on our model, the detection sensitivity of channel permeability is improved by two orders of magnitude over the commonly used experimental conditions. Further, rather than obtaining qualitative preferences of ion selectivity as is typical, we determine quantitative values of these parameters under rigorously controlled conditions even when the experimental results would otherwise imply (without our model) incorrect behavior. We anticipate that this simply employed ultrasensitive assay will find wide application in the quantitative characterization of synthetic or biological ion channels. V.The upregulation or downregulation of microRNA-21 (miRNA-21) is closely related with drug-induced kidney injury (DIKI). As a potential and significant biomarker, the point-of-care testing (POCT) of miRNA-21 is worthy of attention and can provide essential information for clinical diagnosis. Hence, we design a portable and sensitive POCT assay for miRNA-21 using personal glucose meters (PGM). The whole operational system is constructed on streptavidin-coated magnetic beads (MBs) modified with substrate strands linked invertase and DNAzyme molecules each silenced by a locking strand. In the presence of miRNA-21, the locking strand can hybridize to miRNA-21, which originates the activation of the DNAzyme. The DNAzyme cleaves the substrate strands and induces the release of invertase from the surface of MBs. The separated invertase hydrolyzes sucrose to glucose which can be measured by PGM. The dual enzyme mediated catalyzation by DNAzyme and invertase therefore triggers the signal amplification. We establish a linear relationship between PGM and different concentration of miRNA-21 in the range of 100 fM to 1 pM. The limit of detection is 68.08 fM, which is comparable with some of the previous reports. The biosensor also exhibits excellent sequence selectivity, well-presented reproducibility and stability. Notably, by detecting miRNA-21 in urine, this method has been successfully used to predict DIKI and evaluate the protection effect of drugs on DIKI. Therefore, a dependable and low-cost POCT strategy for the detection of miRNA-21 is established, which is promising to supply valuable information for drug screening and evaluation of DIKI. Glycosylation is the most common protein post-translational modification (PTM), especially in biopharmaceuticals. It is a critical quality attribute as it impacts product solubility, stability, half-life, pharmacokinetics and pharmacodynamics (PK/PD), bioactivity and safety (e.g. immunogenicity). Yet, current glycan analysis methods involve multiple and lengthy sample preparation steps which can affect the robustness of the analyses. The development of orthogonal, direct and simple method is therefore desirable. In this study, we suggest use of FTIR spectroscopy to address this challenge. Use of this technique, combined with statistical tools, to compare samples or batches in terms of glycosylation or monosaccharide profile, has three potential applications to compare glycosylation of a biosimilar and the original (innovator) molecule, for monitoring of batch-to-batch consistency, and for in-process control. Fourteen therapeutic monoclonal antibodies (mAbs), one Fc-fusion protein and several other common glycoproteins have been used to demonstrate that FTIR spectra of glycoproteins display spectral variations according to their glycan and monosaccharide compositions. We show that FTIR spectra of glycoproteins provide a global but accurate fingerprint of the glycosylation profile. https://www.selleckchem.com/products/p22077.html This fingerprint is not only sensitive to large differences such as the presence or absence of several monosaccharides but also to smaller modifications of the glycan and monosaccharide content. Due to the extreme infectivity of Yersinia pestis it poses a serious threat as a potential biowarfare agent, which can be rapidly and facilely disseminated. A cost-effective and specific method for its rapid detection at extremely low levels is required, in order to facilitate a timely intervention for containment. Here, we report an ultrasensitive method exploiting a combination of isothermal nucleic acid amplification with a tailed forward primer and biotinylated dNTPs, which is performed in less than 30 min. The polymerase chain reaction (PCR) and enzyme linked oligonucleotide assay (ELONA) were used to optimise assay parameters for implementation on the LFA, and achieved detection limits of 45 pM and 940 fM using SA-HRP and SA-polyHRP, respectively. Replacing PCR with isothermal amplification, namely recombinase polymerase amplification, similar signals were obtained (314 fM), with just 15 min of amplification. The lateral flow detection of the isothermally amplified and labelled amplicon was then explored and detection limits of 7 fM and 0.