A Sensitive Ratiometric Long-Wavelength Fluorescent Probe for Selective Determination of Cysteine/Homocysteine.

The development of sensitive fluorescence probes to detect biothiols such as cysteine and homocysteine has attracted great attention in recent times. Herein, we described the design and synthesis of coumarin based long-wavelength fluorescence probe, Bromo-2-benzothiazolyl-3-cyano-7-hydroxy coumarin (BBCH, 2) for selective detections of cysteine and homocysteine. The probe is rationally designed in such a way that both sulfhydryl and adjacent amino groups of thiols are involved in sensing process. Only cysteine/homocysteine able to react with BBCH to release fluorescence reporter (BCH, 1); while, glutathione and other amino acids unable to react with BBCH due to the absence of adjacent amino groups. In presence of cysteine, the color of BBCH is turns from colorless to red and thus BBCH is a naked eye fluorescence indicator for cysteine. Besides, BBCH can discriminate cysteine and homocysteine based on color changes and different reaction rates. The described sensing platform showed good sensing performances to detect cysteine and homocysteine with detection limits of 0.87 and 0.19 µM, respectively. Practical applicability was verified in biological and pharmaceutical samples.

Metal-enhanced fluorescence through conventional Ag-polyethylene glycol nanoparticles for cellular imaging.

A novel application of conventional Ag nanoparticles (NPs) for metal-enhanced fluorescence (MEF) in cellular imaging is proposed. Different molecular weights of polyethylene glycol (PEG) were tested to determine a suitable spacer on Ag NPs for MEF, and NPs comprising Ag with PEG with a molecular weight of 6000 g (Ag-PEG6k), when present in fluorescein solution, were discovered to cause a 2-fold quantum yield enhancement. For fluorescence imaging of mesenchymal stem cells stained by Alexa Fluor 488, the enhancement factor increased with the Ag-PEG6k NP concentration but decreased with the Alexa Fluor 488 concentration. At 243 parts per billion Ag-PEG6k NPs and 625 parts per million Alexa Fluor 488, the enhancement factor reached its greatest value of over 4.

Bisphenol A-induced DNA damages promote to lymphoma progression in human lymphoblastoid cells through aberrant CTNNB1 signaling pathway.

Lymphoma is a group of blood cancers that develop from the immune system, and one of the main risk factors is associated with exposure to environmental chemicals. Bisphenol A (BPA) is a common chemical used in the manufacture of materials in polycarbonate and epoxy plastic products and can interfere with the immune system. BPA is considered to possibly induce lymphoma development by affecting the immune system, but its potential mechanisms have not been well established. This study performed a gene-network analysis of microarray data sets in human lymphoma tissues as well as in human cells with BPA exposure to explore module genes and construct the potential pathway for lymphomagenesis in response to BPA. This study provided evidence that BPA exposure resulted in disrupted cell cycle and DNA damage by activating CTNNB1, the initiator of the aberrant constructed CTNNB1-NFKB1-AR-IGF1-TWIST1 pathway, which may potentially lead to lymphomagenesis.

Glucose biosensor based on glucose oxidase immobilized at gold nanoparticles decorated graphene-carbon nanotubes.

Biopolymer pectin stabilized gold nanoparticles were prepared at graphene and multiwalled carbon nanotubes (GR-MWNTs/AuNPs) and employed for the determination of glucose. The formation of GR-MWNTs/AuNPs was confirmed by scanning electron microscopy, X-ray diffraction, UV-vis and FTIR spectroscopy methods. Glucose oxidase (GOx) was successfully immobilized on GR-MWNTs/AuNPs film and direct electron transfer of GOx was investigated. GOx exhibits highly enhanced redox peaks with formal potential of -0.40 V (vs. Ag/AgCl). The amount of electroactive GOx and electron transfer rate constant were found to be 10.5 × 10(-10) mol cm(-2) and 3.36 s(-1), respectively, which were significantly larger than the previous reports. The fabricated amperometric glucose biosensor sensitively detects glucose and showed two linear ranges: (1) 10 µM - 2 mM with LOD of 4.1 µM, (2) 2 mM - 5.2 mM with LOD of 0.95 mM. The comparison of the biosensor performance with reported sensors reveals the significant improvement in overall sensor performance. Moreover, the biosensor exhibited appreciable stability, repeatability, reproducibility and practicality. The other advantages of the fabricated biosensor are simple and green fabrication approach, roughed and stable electrode surface, fast in sensing and highly reproducible.