Mcclearyfink7028

Fluctuation of nucleic acid expression and ultrasensitive and specific detection of these variations in expression is a crucial subject in molecular medicine and clinical theranostics. A novel DNAzyme-coupled branched hybridization chain reaction (b-HCR) assay is reported for efficient signal-amplified detection of miRNA in this study. This assay was composed of a translator (T) hybridized with miR-21 to initiate the first HCR by hairpin 1 (H1) and hairpin 2 (H2). The primary HCR provided a backbone chain for numerous branches budding through hairpin 3 (H3) and hairpin 4 (H4) assembles. In the presence of hemin, the G-rich domains embedded in H1 and H4 produce an active G-quadruplex DNAzyme upon exposure to a target that could catalyze the oxidation of colorless substrate to colored product. The present approach has the potential to be used for quantitative detection of miR-21 with a sensitivity and a dynamic range of 1 pM and 1 pM to 1 nM, respectively.MicroRNAs (miRNAs) have been regarded as potential biomarkers in early diagnosis of cancer. Since the high sequence similarity among miRNA family members, biosensing miRNAs with single-base resolution is still a challenge, particularly when the different base is located at the terminal of miRNA. Herein, we developed two real-time fluorescence monitoring methods for miRNA detection utilizing efficient PBCV-1 DNA ligase mediated target miRNA dependent DNA ligation, followed by rolling circle signal amplification. Compared to duplex-specific nuclease (DSN) enhanced rolling circle transcription (RCT) system, nicking endonuclease (NEase) assisted rolling circle amplification (PRCA-NESA) can provide higher amplification efficiency, and achieve a limit-of-detection of 0.5 amol for miR-17 in 10 μL sample. More importantly, benefiting from the unique characteristics of PBCV-1 DNA ligase, we designed an asymmetric PRCA-NESA method, which can greatly discriminate the single-base difference at either 5'- or 3'-terminals of miRNAs. MiR-17 from various tumor cells also can be reliably detected. In conclusion, our strategy exploited the application potential of PBCV-1 DNA ligase in biosensing, and provided a new idea to highly specific miRNA detection, thereby would possess a promising potential for further application in biomedical research and early cancer diagnosis.This work proposes a simple device for thermometric titration using a contactless sensor. A low-cost infrared sensor (around $5) was adapted in a disposable, polystyrene vessel for monitoring the temperature to determine the endpoint of neutralization, redox, and complexation titrations, using a homemade syringe pump to titration control. Open-source software was developed to control the device using the Raspberry Pi platform and to perform automatic endpoint determination. The influence of sample volume, the flow rate of titrant, and sensor distance from the solution were evaluated to lower the variation among measurements. The parameters chosen in this regard were 10 mL of sample, 0.8 mL min-1 of titrant solution flow rate, and 3 cm of distance from the sensor to the solution. Results for the determination of the acidity of sauces and the ascorbic acid and calcium content of pharmaceutical products were compared with those from official compendia. The performance of the sensor also was compared with an infrared camera. The proposed method agreed with conventional ones to an extent ranging from 93% to 106%. The robust analytical performance and low cost of the system are essential features that could broaden the use of enthalpimetric analysis in several laboratories.A phenomenon of supramolecular solvents formation in aqueous solutions containing primary amine and monoterpenoid compound is presented for the first time. A novel supramolecular solvent-based liquid phase microextraction was developed. In an aqueous phase primary amine formed isotropic solution due to formation of amphiphile supramolecular assembly. The phase separation was achieved by a coacervation process. The monoterpenoid phenol (thymol) acted as a coacervation agent and induced spontaneous in situ formation of tiny supramolecular solvent droplets. The applicability of the proposed microextraction procedure was demonstrated for the separation of sulfonamides from biological fluids (human plasma and serum). An obtained composition of supramolecular solvent (1-decylamine, thymol, water) promoted satisfactory extraction of polar analytes from aqueous phase. The calibration graphs were linear over the concentration ranges of 0.06-50 mg L-1 for sulfamethoxazole, sulfamethazine and sulfapyridine. The limit of detection calculated from the blank tests based on 3σ was 0.02 mg L-1 for all analytes. The total analysis time was 15 min.We describe a novel polymer-based zwitterionic stationary phase for hydrophilic interaction chromatography (HILIC). It is prepared by chemical modification of poly (glycidyl methacrylate-divinylbenzene) (GMA-DVB) by converting epoxide groups of microsphere surface to diol groups via hydrolysis, then clicking cysteine onto the microsphere with pendant double bonds of microsphere surface via "thiol-ene" click chemistry. The phase has been characterized by scanning electron micrograph, elemental analysis and zeta potential measurement. Diol and zwitterionic group (carboxylate and amine group associated with cysteine) onto the surface of GMA-DVB microspheres make them possess good hydrophilicity, as supported by effective separation towards common polar analytes. It shows good stability at alkaline solution (e.g. pH 10) and negligible bleed (e.g. only 1.7-fold blank and ~55-fold lower than a commercial silica-based polar phase tested with the minimal bleed level). Such phase exhibits specific separation selectivity to ionic analytes and simultaneous separation of anions and cations is achieved in the retention order of I- less then NO3- less then Choline less then Br- less then Cl- less then K+ less then Na+.Solvents with both low density and viscosity have the advantage of higher extraction efficiency due to lower diffusivity and consequently higher mass transfer. In this study, a mixture design was performed for the synthesis of three different natural deep eutectic solvents (NADES) using citric acid, malic acid, and xylitol. The optimized proportion for each of the three solvents synthesized was selected based on density and viscosity values. The NADES were characterized by infrared spectroscopy analysis, that showed characteristic bands of the initial reagents and the presence of hydrogen bonds confirming the formation of each deep eutectic solvent. Then, the NADES were used as solvents in ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE) of biological tissue and plant material samples for the determination of As, Cd, Hg, Pb, Se, and V by inductively coupled plasma mass spectrometry (ICP-MS). The results for the proposed methods were compared to microwave-assisted acid digestion (MW-AD). The extraction recoveries ranged from 80 to 120% for most of the elements determined. The use of NADES as carbon sources improved the sensitivity of the As and Cd analyses, due to charge transfer reactions between the analyte and C+ and/or other carbon species. In addition, the Analytical Eco-Scale was used to assess the greenness of the proposed analytical procedures (UAE and MAE). It showed that the UAE and MAE methods provided excellent green analyses, while the MW-AD method was rated as an acceptable green procedure.Herein we propose, for the first time, a rapid method based on flow injection analysis, electrospray ionization-tandem mass spectrometry (FIA-ESI-MS/MS) and multivariate calibration for the determination of l-leucine, l-isoleucine and L-allo-isoleucine in saliva. As far as we know, multivariate calibration has never been applied to the data from this non-separative approach. The possibilities of its use were explored and the results obtained were compared with the corresponding ones when using univariate calibration. Partial least square regression (PLS1) multivariate calibration models were built for each analyte by analyzing different saliva samples, and were subsequently applied to the analysis of another set of samples which had not been used in any calibration step. For Leu, the model worked satisfactorily with root mean square errors in the prediction step of 17%. This error can be considered acceptable and is common in methodologies that do not include a separation step. Results were compared with thosseparation is recommended to confirm the results.Bisphenol A is one the most relevant endocrine disruptors for its toxicity and ubiquity in the environment, being largely employed as raw material for manufacturing processes of a wide number of compounds. Furthermore, bisphenol A is released in the drinking water when plastic-based bottles are incorrectly transported under sunlight, delivering contaminated drinking water. For the health of human beings and the environment, rapid and on site detection of bisphenol A in drinking water is an important issue. Herein, we report a novel and cost-effective printed electrochemical sensor for an enzymatic-free bisphenol A detection. This sensor encompasses the entire electrochemical cell printed on filter paper and the reagents for the measurement loaded in the cellulose fiber network, for delivering a reagent-free analytical tool. The working electrode was printed using ink modified with carbon black, a cost effective nanomaterial for sensitive and sustainable bisphenol A determination. Several parameters including pH, frequency, and amplitude were optimized allowing for a detection limit of 0.03 μM with two linear ranges 0.1-0.9 μM and 1 μM-50 μM, using square wave voltammetry as electrochemical technique. The satisfactory recovery values found in river and drinking water samples demonstrated the suitability of this sensor for screening analyses in water samples. These results revealed the attractiveness of this paper-based device thanks to the synergic combination of paper and carbon black as cost-effective materials.The performances of three commercial albumin extraction methods for the isolation of intact albumin-amyloid beta peptide (HSA-Aβ) complexes from serum were compared using different analytical approaches. To determine the extraction yield, the repeatability and the selectivity of the extraction procedures, a capillary electrophoresis coupled to UV detection method was developed. For the evaluation of the specificity and integrity of the extracted HSA-Aβ complexes, SDS-PAGE, hybrid and ultra-sensitive ELISA experiments were conducted. selleck products All the extraction methods showed different characteristics depending on their chemical binding affinities toward albumin. The ProteoExtract Albumin Depletion kit extracted albumin with a high repeatability but was not efficient for the extraction of intact HSA-Aβ complexes. The PureProteome Albumin magnetic beads showed a high specificity toward HSA thanks to the grafting of anti-HSA antibodies on their surface but tended to dissociate HSA from Aβ peptides. The Pierce Albumin depletion kit showed a high extraction yield, no selectivity towards the different albumin proteoforms and proved to be the most efficient method for the extraction of intact HSA-Aβ complexes from serum.