Rowestafford4879

This paper demonstrated a simple and validated fluorescence enhancing method to selectively recognize and discriminate the amino acid phenylalanine (Phe). 1H NMR spectroscopy reveal that the palmatine (PAL) can be encapsulated into the cucurbit [8]uril (Q [8]) in aqueous solution to form stable 12 host-guest inclusion complex PAL2@Q [8], which exhibits moderate intensity fluorescence property. Interestingly, the addition of the Phe into the inclusion complex PAL2@Q [8] leads to dramatically enhancing of the fluorescence intensity. In contrast, the addition of any other natural amino acids into the inclusion complex PAL2@Q [8] gives no fluorescence variation. Furthermore, it is easy to detect the concentration of Phe in target aqueous solution according to the linear relationship between fluorescence intensity and concentration of the Phe. A novel fluorescence sensing strategy for ultrasensitive and highly specific detection of adenosine triphosphate (ATP) has been developed by the combination of the proximity ligation assay with bidirectional enzymatic repairing amplification (BERA). The strategy relies on proximity binding-triggered the release of palindromic tail that initiates bidirectional cyclic enzymatic repairing amplification reaction with the aid of polymerase and two DNA repairing enzymes, uracil-DNA glycosylase (UDG) and endonuclease IV (Endo IV). A fluorescence-quenched hairpin probe with a palindromic tail at the 3' end is skillfully designed that functions as not only the recognition element, primer, and polymerization template for BERA but also the indicator for fluorescence signal output. On the basis of the amplification strategy, this biosensor displays excellent sensitivity and selectivity for ATP detection with an outstanding detection limit of 0.81 pM. Through simultaneously enhancing the target response signal value and reducing nonspecific background, this work deducted the background effect, and showed high sensitivity and reproducibility. Moreover, our biosensor also shows promising potential in real sample analysis. Therefore, the proximity-enabled BERA strategy indeed creates a simple and valuable fluorescence sensing platform for ATP identification and related disease diagnosis and biomedical research. A new paper-based analytical device based on bulk ion-selective optodes (ISOs) for dual Ag+ and Hg2+ detection has been developed. A plasticized PVC hydrophobic phase composed of 25,27-di(benzothiazolyl)-26,28-hydroxycalix[4]arene (CU1) as an ion-selective ionophore, potassium tetrakis(4-chlorophenyl)borate as an ion-exchanger and chromoionophore XIV as a lipophilic pH indicator was entrapped in the pores of cellulose paper. This paper strip showed higher selectivity for Ag+ and Hg2+ over common alkali, alkaline earth and some transition metal ions with a color change from blue to yellow. With the proposed sensor, Ag+ and Hg2+ can be measured with the range of 1.92 × 10-6 to 5.00 × 10-3 M for Ag+ and 5.74 × 10-7 to 5.00 × 10-5 M for Hg2+ with a limit of detection of 1.92 × 10-6 M for Ag+ and 5.74 × 10-7 M for Hg2+. The proposed sensor was successfully applied to determine the amount of mercury in various water sources and the amount of silver in cleaning product samples containing silver nanoparticles (AgNPs). The results were in good agreement with inductively couple plasma-optical emission spectrometric measurements (ICP-OES). Blood glucose measurement plays a very important role in clinical diagnosis and fluorescence analysis has attracted extensive attention. A novel ratiometric fluorescent system with aggregation induced emission (AIE) property for the detection of glucose was established in this work. In this system, bovine serum albumin-stabilized Au nanoclusters (BSA-AuNCs) served both as the fluorescent detection probe and the AIE inducer. An AIE molecule, named sodium 1,2-bis [4-(3-sulfonatopropoxyl) phenyl]-1,2-diphenylethene (BSPOTPE), served as fluorescent reference probe. In the presence of H2O2, the fluorescence intensity of BSPOTPE/BSA-Au NCs at 680 nm progressively decreased while that at 490 nm remained constant. Glucose can be catalyzed by glucose oxidase (GOx) and produces H2O2. Therefore, glucose detection can be conveniently achieved by the proposed strategy. The fluorescence intensity change ratio increased linearly with the glucose concentration in the range 1-8 mM. Moreover, the proposed method exhibits a consecutive fluorescence color change ("from red to cyan") to glucose concentration in the range of 1-8 mM under a 365 nm UV lamp and exhibits bright "red" or bright "cyan" in lower glucose concentrations (lower than 3 mM) or high glucose concentrations (higher than 7 mM), respectively. find more The work offers an ideal rapid clinical diagnostic method for both normal and abnormal blood glucose screening. Herein, we report a new probe for the determination of the concentration of NF-κB p50, one kind of DNA-binding transcription factors (TFs), by using Exonuclease III (Exo III)-aided amplification and gold nanoparticle mediated fluorescence intensity. Since TFs play critical roles in various biological processes, the detection of TFs can provide a lot of useful biological information for studding gene expression regulation related disease. In our system, in the presence of transcription factor, Exo III based amplification reaction was trigged. This enzymatic digestion results in the release of intermediate DNA and ultimately liberating the fluorophore (which, separated from the quencher of AuNP and BHQ2, now fluoresces). The released intermediate DNA then hybridizes with another strand3, whence the cycle starts anew. So, the fluorescence intensity reflects the NF-κB p50 concentration with a detection limit of 1.32 pM. Importantly, this method might be further extended to selectively detect various dsDNA-binding proteins by simply changing the binding-site sequences of strand1/strand2 duplex probes. We report on the synthesis of manganese oxide doped CDs (MnOx-CDs) by a hydrothermal strategy using manganese (III) acetylacetonate (Mn(III) (C5H7O2)3) as the only raw materials. The MnOx-CDs exhibit water solubility, favorable biocompatibility, low cytotoxicity, and show blue fluorescence with excitation/emission maxima at 326/442 nm with a quantum yield of 11.3%, allowing efficient cellular imaging. The MnOx-CDs have a reversible temperature-sensitive fluorescent property in vitro within 10-60 °C, which can also be used as a sensitive thermometer in living cells. By a scratch assay, the MnOx-CDs can restrain the migration of HepG2 cancer cells, which make the MnOx-CDs be attractive candidates for liver cancer adjuvant treatment. Besides, the fluorescence of the MnOx-CDs is quenched in the presence of Fe3+ due to the formation of a nonfluorescent MnOx-CDs-Fe3+ complex between oxygen-containing groups on the surface of MnOx-CDs and Fe3+, and the quenched fluorescence of MnOx-CDs can be turn-on by dissociation of MnOx-CDs-Fe3+ complexes by biothiols including L-cysteine, homocysteine and glutathione.