Traffic light-type ratiometric fluorescence visual sensing of Cs+ in soybean oil based on dimension regulation of 2D perovskite nanosheets.

Determination of cesium ion in soybean oil is of high importance since the increasing risk from releasing of main component of nuclear waste cesium 137. The complex composition and high viscosity of soybean oil make it necessary to convert it into water phase by nitration before detection, so developing a simple, accurate and sensitive method for on-site sensing of Cs+ in soybean oil is still a big challenge. In this work, we report a traffic light-type ratiometric fluorescence strategy for the visual sensing of Cs+ in soybean oil based on dimensional regulation of two dimensional (PEA)2PbI4 perovskite nanosheets (NSs). The PEA+ in (PEA)2PbI4 NSs exchanged with Cs+ and lead to dimension of partial (PEA)2PbI4 NSs progressively increase from 2D to 3D CsPbI3 NCs. Resultantly, the fluorescence of (PEA)2PbI4 NSs decreases with a concomitant fluorescence enhancement of CsPbI3 NCs upon increasing the concentrations of Cs+, and the emission accordingly change from green, yellow to red with a high fluorescence colorimetric resolution up to 5.0 µM, make it successful to achieve on-site sensing of Cs+ in soybean oil just with naked eye in 5 min without any nitration, demonstrating a bright application future for determination of Cs+ in the soybean oil.

Colorimetric sensing of chloride in sweat based on fluorescence wavelength shift via halide exchange of CsPbBr3 perovskite nanocrystals.

Considering the high importance of the rapid detection of chloride ion (Cl-) in sweat for the diagnosis of fibrotic cysts, we have investigated the heterogeneous halide exchange between CsPbBr3 perovskite nanocrystals (PNCs) in n-hexane and Cl- in aqueous solution. The results show that CsPbBr3 PNCs could achieve fast halide exchange with Cl- in the aqueous phase under magnetic stirring at pH = 1, accompanied by a significant wavelength blue shift and vivid fluorescence color changes from green to blue. Therefore, a fluorescence wavelength shift-based colorimetric sensing of Cl- based on the halide exchange of CsPbBr3 PNCs has been developed to realize the rapid detection of Cl- in sweat. Compared with the conventional fluorescence intensity-based method, this method is of high convenience since the whole procedure could be achieved within 5 min without any sample pretreatment (even no dilution), demonstrating promising application prospects. Graphical Abstract Fluorescence wavelength-shift based colorimetric sensing of chloride in sweat via halide exchange of CsPbBr3 perovskite nanocrystals.

Dual-Mode of Fluorescence Turn-On and Wavelength-Shift for Methylamine Gas Sensing Based on Space-Confined Growth of Methylammonium Lead Tribromide Perovskite Nanocrystals.

The defect-tolerant nature of lead halide perovskites renders outstanding luminescence by simple space-confined growth in nanopores. The fluorescence turn-on and wavelength-shift phenomena could be found in the formation of methylammonium lead tribromide (MAPbBr3) nanocrystals in hollow SiO2 nanospheres triggered by the reaction between methylamine (MA) gas and HPbBr3/PbBr2@SiO2 nanospheres. The enhanced fluorescence intensity is linear with the MA concentration in the range of 1.0-95 ppm with a limit of detection (LOD) of 70 ppb (S/N = 3). In addition, the maximum emission wavelength is consistently red-shifted from 478.7 to 510.6 nm as the MA concentration increases from 1.0 to 95 ppm, imparting the potential for colorimetric sensing. By combining the fluorescence turn-on and colorimetric sensing modes, the flexible method meets the demands for visual discrimination and point-of-care determination with portable devices.

Wavelength-Shift-Based Colorimetric Sensing for Peroxide Number of Edible Oil Using CsPbBr3 Perovskite Nanocrystals.

The peroxide number of edible oil relates to its quality. The classical determination methods for the peroxide number are still unsatisfactory due to their complexity and poor reproducibility in the analytical process and their incapability of field rapid detection. In this study, a novel wavelength-shift-based visual method has been developed for the peroxide number determination of edible oil using halide perovskite nanocrystals (CsPbBr3 NCs). In the analysis, the edible oil sample underwent redox reactions with a part of oleylammonium iodide (OLAM-I) in advance. Then, the halogen exchange occurred between the added CsPbBr3 NCs and the iodide ions from the residual OLAM-I. The resulting wavelength shift of the fluorescence emission reflects the peroxide number in the edible oil sample. Under the ultraviolet light excitation at 365 nm, the apparent color of the photoluminescence could directly be compared with a color chart to determine and qualify the peroxide number. Using the approach, the visual detection of the peroxide number of edible oil samples on site could be realized. The detection process takes only ∼15 min and is convenient and accurate.

A cytotoxicity study of fluorescent carbon nanodots using human bronchial epithelial cells.

The labeling of living cells with carbon nanoparticles has been increasingly studied both in vivo and in vitro, but concerns about the potential cytotoxicity of these nanoprobes are also increasing. In this study, the fluorescent carbon dots (CDs) without surface modification was synthesized and evaluated for its cytotoxicity. Indicators including cell viability, total reactive oxygen species (ROS), glutathione, malondialdehyde and lactate dehydrogenase were assessed using human bronchial epithelial (16HBE) cell line. Our results showed that CDs preferred to locate on the surface of cells, which significantly increased the membrane permeability of 16HBE cells. CDs exposure could further induce oxidative stress, exhaust the antioxidant defenses of cells and finally lead to decreased cell viability. Therefore, surface modification of CDs is needed to minimize its cytotoxicity. The present work is useful for the development of new strategies towards the in vitro and in vivo applications of CDs for optical imaging and drug delivery.

8-Quinolineboronic acid as a potential phosphorescent molecular switch for the determination of alpha-fetoprotein variant for the prediction of primary hepatocellular carcinoma.

8-Quinolineboronic acid phosphorescent molecular switch (8-QBA-PMS) in the "off" state emitted weak room temperature phosphorescence (RTP) of 8-QBA on the acetylcellulose membrane (ACM) with the perturbation of Pb(2+). When 8-QBA-PMS was used to label concanavalin agglutinin (Con A) to form 8-QBA-PMS-Con A based on the reaction between -OH of 8-QBA-PMS and -COOH of Con A, 8-QBA-PMS turned "on" automatically due to its structure change, and RTP of the system increased 2.7 times. Besides, -NH(2) of 8-QBA-PMS-Con A could carry out affinity adsorption (AA) reaction with the -COOH of alpha-fetoprotein variant (AFP-V) to form the product Con A-AFP-V-Con A-8-QBA-PMS containing -NH-CO- bond, causing the RTP of the system to further increase. Moreover, the amount of AFP-V was linear to the DeltaI(p) of the system in the range of 0.012-2.40 (fg spot(-1)). Thus, a new affinity sensitive adsorption solid substrate room temperature phosphorimetry using 8-QBA-PMS as labelling reagent (8-QBA-PMS-AASSRTP) for the determination of AFP-V was proposed with the detection limit (LD) of 9 x 10(-15) g mL(-1). It had been used to determine AFP-V in human serum with the results agreeing with enzyme-link immunoassay (ELISA), showing promise for the prediction of PHC due to the intimate association between AFP-V and primary hepatocellular carcinoma (PHC). The mechanism of the promethod was also discussed.

[Analysis of factors related to delay in pathology reporting].

OBJECTIVE: To investigate the factors related to delay in pathology reporting and to improve the quality of pathology service. METHODS: A total of 24 months pathology reports (total number = 21,038) issued by Department of Pathology, Dongyang People's Hospital (randomly selected during the period from 1999 to 2006) were analyzed. The timeliness of these reports was studied with respect to the types of specimens (biopsy versus surgical versus frozen section). The causes for delay in reporting were statistically analyzed. RESULTS: Among all the cases studied, 19,579 reports were timely issued (timeliness rate = 93.06%), whereas 1459 reports were delayed (delay rate = 6.94%). Of the 1459 delayed reports, routine biopsy specimens accounted for 6.02% (665/11,052), surgical specimens for 7.26% (643/8858) and frozen section specimens for 13.39% (151/1128). The main causes for delay in reporting were technical (1158 cases or 79.37%), including requests of immunohistochemical staining, intradepartmental or external consultation, patient contact and discussion with requesting clinicians. Factors related to responsibility, such as inadequate clinical information in the pathology request forms, were identified in 301 cases (20.63%). The delay in reporting was mainly due to factors occurring within the pathology department (which accounted for 1048 cases or 71.83% (P < 0.05) and most were technical (1017 cases or 97.04%). Extradepartmental factors, mainly related to responsibility, were noted in 270 cases (65.69%, chi2 = 709.59, P < 0.05). CONCLUSION: Factors related to delay in pathology reporting can be categorized into technical and responsibility. The former can be rectified by improvement of laboratory procedures, while the latter needs education of the personnel concerned.

[Detection of IgH gene rearrangement in B-cell non-Hodgkin's lymphoma and application of gel-scan method].

OBJECTIVE: To develop a protocol for gene rearrangement study in non-Hodgkin's lymphoma (NHL) by PCR-directed gel-scan method and to set up quantitative criteria for IgH gene rearrangement which can be applied in the follow up of lymphoma patients. METHODS: IgH gene rearrangement studies were carried out in 96 cases of B-cell NHL. The detection rate of clonality was evaluated. Sixty-five cases of IgH gene rearranged cases proven by FR3A-directed PCR and PAGE and 8 cases of benign lymphoid tissues (5 cases of reactive lymphoid hyperplasia, 3 cases of chronic tonsillitis), 5 cases of normal peripheral blood mononuclear cells were analyzed by gel-scan method and the proportion of h1/h2 (heights of peak1 and peak2 of gel-scan) was calculated. RESULTS: The detection rate of IgH gene clonality was up to 68% using primer FR3A in the 96 B-cell NHL cases. The detection rate was up to 61% using primer FR2A. With a combination of primers FR3A and FR2A, the detection rate increased to 83%. Gel-scan curve showed that the value of h1/h2 was greater than 3 in all the 65 cases with IgH gene rearranged. In the 8 benign lymphoid tissue cases showed h1/h2 < 1.5, 5 cases with normal peripheral blood mononuclear cells showed a bell-shaped curve. CONCLUSIONS: In the gel-scan curve of gene rearrangement studies in non-Hodgkin's lymphoma samples, the value of h1/h2 greater than 3 represents a true clonal proliferation. The peaks with relative heights less than 1.5 may not be significant and likely represent polyclonal cell population. A value between 1.5 and 3 however requires clinical follow-up. The success rate of rearrangement studies in B-cell NHL can be increased by using a combination of primers FR3A and FR2A.