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An array of piezoelectric quartz crystal sensors (PQCs) has been prepared for analyzing organic vapor mixtures. The circuit of oscillators has been modified and optimized to circumvent the problems associated with mutual interference among different oscillators connecting to sensors in the array. Organic coating materials were clustered into four groups according to their polarity and compounds representing different groups were selected including silicone OV-101, silicone OV-17, silicone OV-275, span 85, and polyethylene glycol 1000. The sensor array constructed gives characteristic response patterns for different organic vapors such as methanol, 1,2-dichloroethane, benzene and cyclohexane. The feasibility of using the sensor array for analysis of binary and tertiary mixtures has been tested by using PLS and MLR data treatment algorithms. [Copyright &y& Elsevier]

Rhodamine fluorophore has attracted increasing attention due to its good stability and high fluorescence quantum yield. However, it is still a challenge to design long-wavelength rhodamine with high performance. In this work, by the reasonable design, we have constructed a novel rhodamine fluorophore YL602-F. YL602-F not only displays long absorption/emission (602/638 nm), but also possesses excellent chemical stability, high brightness (φ × ε/M-1 cm-1 = 26,450), environmental insensitive emission and easy synthesis, thus displaying a good potential for bioimaging application. As a proof-of-concept, based on dye YL602-F , we then designed and developed a nitric oxide-activated fluorescent probe YL602-F-NO. Experiment results showed that probe YL602-F-NO could respond to NO with a 35-fold fluorescence enhancement together with a high sensitivity and the detection limit was calculated to be 83.1 nM. Notably, YL602-F-NO has also been successfully used to sensitively recognize endogenous NO in cells and living mice, especially for real-time monitoring of NO levels in a mouse model of DSS-induced enteritis. We expect the YL602-F fluorophore to be a promising molecule that will help researchers develop activated fluorescent probes with even better performance. [Display omitted] • Constructing a novel rhodamine fluorophore YL602-F with long absorption/emission. • Possessing excellent chemical stability, high brightness, environmental insensitive emission and easy synthesis. • Developing a nitric oxide-activated fluorescent probe YL602-F-NO with a high sensitivity. • Real-time monitoring of NO levels in a mouse model of DSS-induced enteritis. [ABSTRACT FROM AUTHOR]

Near-infrared (NIR) fluorescent probes have been considered as powerful tools for exploring bioactive species and biological processes in living systems by virtue of the substantial merits of the NIR window (such as minimal photo-toxicity, deep tissue penetration, and low background interference). However, the development of effective NIR fluorescent probes for biological application is still facing great challenges due to some weakness (for example, pH sensitivity, poor chemical and photo-stability) of mainly current NIR fluorophores. Herein, we synthesized a novel fluorine atom substituted NIR chromenylium-cyanine fluorophore, termed CCF-OH , with an optically tunable hydroxyl group. Compound CCF-OH possess several optical advantages, including high chemical stability, high photo-stability, and high fluorescence quantum yield (Φ = 0.47). Significantly, a low pK a value (6.3) of CCF-OH was obtained, making its fluorescence signal steady around the pH ranging from 6.8 to 8.1. To demonstrate the practicability of CCF-OH , a mitochondria-targeted near-infrared fluorescent probe, N-Cys , was developed by masking the hydroxyl group of CCF-OH with an acrylate group as the recognition unit for cysteine (Cys). N-Cys responded to Cys with an obvious ratiometric signal. Furthermore, N-Cys has also been successfully applied for ratiometric NIR imaging of Cys in living cells, suggesting the great potential of the new NIR fluorophore, CCF-OH , for practical applications in living systems. [ABSTRACT FROM AUTHOR]

Superoxide anion radical (O 2 − ), the “primary” reactive oxygen species (ROS) in living systems, is linked to a variety of physiological and pathological processes. Therefore, developing an effective strategy to monitor the fluctuation of O 2 − in biological systems is of great importance. This paper describes a new turn-on two-photon fluorescent probe for endogenous O 2 − detection and imaging, which was rationally designed and synthesized via a non-redox strategy. In the presence of O 2 − , the probe exhibited notable fluorescence enhancement (∼235-fold) with a low detection limit down to 1 nM, indicating a high signal-to-background ratio and excellent sensitivity. In addition, short response time, good biocompatibility, low cytotoxicity, long-term stability against light illumination, specificity to O 2 − over general reductants, and pH stability were demonstrated, indicating that the requirements for cellular O 2 − determination are met. Furthermore, the probe was successfully applied in two-photon fluorescence imaging of endogenous O 2 − in living cells and tissues and showed high imaging resolution and a deep-tissue imaging depth of ∼150 μm, illustrating the promising potential for practical applications in complex biosystems and providing a valuable theoretical basis and technical support for the study of physiological and pathological functions of O 2 − . [ABSTRACT FROM AUTHOR]

Abstract: An electrochemical amplification immunoassay is reported using biocatalytic metal deposition coupled with anodic stripping voltammetric detection. In this method, the captured antibody was first immobilized onto a gold electrode via a self-assembled layer. After a sandwich immunoreaction, alkaline phosphatase-labeled antibody was bound to the gold electrode. The alkaline phosphatase on the electrode catalyzes the hydrolysis of ascorbic acid 2-phosphate to produce ascorbic acid. The latter, in turn, reduced silver ions on the electrode surface, leading to the deposition of silver onto the protein-modified electrode surface. The deposited metal was electrochemically stripped into solution and then measured by anodic stripping voltammmetry. Compared with the direct voltammetric detection of ascorbic acid, anodic stripping voltammetric detection of metal ions is more sensitive. For the amount of deposited silver relates to the amount of enzyme-generated ascorbic acid, which was controlled by the amount of enzyme bound on the electrode surface, the stripping current signal reflects the amount of target protein, achieving a linearly relationship in the range from 5 to 1000ngmL−1 in a logarithmic plot with a detection limit of 2.2ngmL−1. The utilization of the high biocatalytic activity of enzyme and the sensitive anodic stripping voltammetry to detect metal ions dramatically enhanced the sensitivity in immunoassay. [Copyright &y& Elsevier]

• This R-CDs have deep tissue penetration ability, little damage to biological matrix. • They were successfully used to monitor the change of intracellular polarity. • They can discriminate polarity differences between normal and cancer cell lines. • This nanoprobe possesses dual mitochondria and lysosome targetability Intracellular polarity has a large impact on the activity of a series of biomolecules or maintain the function of particular domains. Therefore, monitoring the changing of intracellular polarity can great improve the understanding its functions in living cell level. Herein, by employing p-phenylenediamine as precursor, we prepared a red emissive carbon dots based nanoprobe for real-time sensing polarity in living cells. With the increasing of the polarity, a large red shift of fluorescence emission wavelength was obtained and the fluorescence intensity of red emissive carbon dots decreased about 11-fold when the solvent changed from 10 % to 99 % water. The red emissive carbon dots possess high quantum yield, high photo-stability, good biocompatibility as well as robust dual targetability for mitochondria and lysosome. Finally, the red emissive carbon dots were successfully used to discriminate polarity differences between normal and cancer cell lines. [ABSTRACT FROM AUTHOR]