A Drosophila heart optical coherence microscopy dataset for automatic video segmentation.

The heart of the fruit fly, Drosophila melanogaster, is a particularly suitable model for cardiac studies. Optical coherence microscopy (OCM) captures in vivo cross-sectional videos of the beating Drosophila heart for cardiac function quantification. To analyze those large-size multi-frame OCM recordings, human labelling has been employed, leading to low efficiency and poor reproducibility. Here, we introduce a robust and accurate automated Drosophila heart segmentation algorithm, called FlyNet 2.0+, which utilizes a long short-term memory (LSTM) convolutional neural network to leverage time series information in the videos, ensuring consistent, high-quality segmentation. We present a dataset of 213 Drosophila heart videos, equivalent to 604,000 cross-sectional images, containing all developmental stages and a wide range of beating patterns, including faster and slower than normal beating, arrhythmic beating, and periods of heart stop to capture these heart dynamics. Each video contains a corresponding ground truth mask. We expect this unique large dataset of the beating Drosophila heart in vivo will enable new deep learning approaches to efficiently characterize heart function to advance cardiac research.

Nitrogen and bromine co-doped carbon dots with red fluorescence for sensing of Ag+ and visual monitoring of glutathione in cells.

Carbon dots (CDs) with red fluorescence emission have excellent advantages in cell imaging. Herein, novel nitrogen and bromine doped CDs (N,Br-CDs) were prepared with 4-bromo-1,2-phenylenediamine as precursor. The N, Br-CDs present the optimal emission wavelength at 582 nm (λex = 510 nm) at pH 7.0 and 648 nm (λex = 580 nm) at pH 3.0 âˆ¼ 5.0, respectively. The fluorescence intensity of N,Br-CDs at 648 nm versus Ag+ concentration shows a good relationship from 0 to 60 µM with the limit of detection (LOD) of 0.14 µM. Furthermore, the fluorescence of N,Br-CDs/Ag+ is efficiently restored via the combination of glutathione (GSH) and Ag+ and linearly changes with GSH concentration from 0 âˆ¼ 6.0 µM with LOD of 49 nM. This method has been successfully employed to monitor intracellular Ag+ and GSH with fluorescence imaging. The results suggest that the N,Br-CDs has application potential in the sensing of Ag+ and visual monitoring of GSH in cells.

Carbon quantum dots with pH-responsive orange-/red-light emission for fluorescence imaging of intracellular pH.

N-doped carbon quantum dots (N-CDs) with polyaminobenzene hydrazine as precursor were prepared by solvothermal method for the monitoring of pH fluctuation in HeLa cells via fluorescence imaging. The N-CDs show two emission wavelengths at 582 and 640 nm under different pH with two excitation wavelengths. The fluorescence intensity at 640 nm (λex = 520 nm) and the ratio of F582/F640 (λex = 470 nm) linearly increase with pH in the range of 2.4 ~ 3.6 (R2 = 992) and 5.6 ~ 7.6 (R2 = 0.987), respectively. The sensor exhibits high sensitivity and reversibility and anti-interference capability, thus enabling sensing pH change in intracellular environment in real time, as demonstrated by successful monitoring of intracellular pH fluctuation during H2O2 stimulation in HeLa cells.

Nitrogen and fluorine co-doped green fluorescence carbon dots as a label-free probe for determination of cytochrome c in serum and temperature sensing.

As an important biomarker, the analysis of cytochrome c (Cyt c) plays a crucial role in cell-apoptosis or even cancer diagnosis. This work develops a label-free probe for Cyt c using the nitrogen and fluorine co-doped carbon dots (N, F-CDs) which were facile prepared through solvothermal method with 3, 4-difluorophenylhydrazine as precursor. The N, F-CDs have an average diameter of 3.4 nm, and can form a quite stable colloidal solution. The N, F-CDs show bright yellow-green fluorescence, excitation/emission wavelengths 475/530 nm, and a relatively high fluorescence quantum yield of 16.9%. Interestingly, the N, F-CDs indicate a linear and reversible variation of emission intensity with a sensitivity of -1.11% per ℃ in the temperature range from 25 to 60 ℃. Inner filter effect (IFE) between N, F-CDs and Cyt c turns the fluorescence of N, F-CDs from "on" to "off". The sensor possesses the excellent anti-interference ability towards the main components of plasma. Under optimum conditions, there is a linear relationship between fluorescence intensity function (F0-F) and the concentration of Cyt c in the range of 0.5-25 µΜ with a limit of detection (LOD) (S/N = 3) of 0.25 µM. Finally, the developed method has been successfully used to detect Cyt c in human serum sample with satisfactory recoveries in a range of 93.14-110.40%.

Tetrazole-functionalized cation-exchange membrane adsorbers with high binding capacity and unique separation feature for protein.

The modification with high-density functional groups is a widely used method to enhance the binding capacity of membrane adsorbers, where the types of the attached groups are crucial to achieve good selectivity for protein separation. In this work, a novel tetrazole-functionalized weak cation-exchange membrane with high-capacity was prepared by constructing tetrazole-containing polymer brushes on the surface of regenerated cellulose membrane via the combination of surface-initiated atom transfer radical polymerization (SI-ATRP) and "click chemistry" between cyano and azide. Densities of tetrazolyl groups on the membranes can be easily controlled by manipulating the polymerization time. The binding capacity of lysozyme increased with the polymerization time but eventually reached maximum due to the reduction of the utilization percentage of ion-exchange sites. The adsorption of newly designed membrane conforms to the feature of weak cation exchanger in terms of pH and salt effects, whereas the effect of pH exhibits a large difference from that on the carboxylic-functionalized ion-exchange membranes. Most importantly, the membranes possess higher dynamic binding capacity independent of the flow rate of mobile phase compared with the previously reported cation-exchange membranes. Featured with the unique properties, the modified membrane could simultaneously purify lysozyme and ovotransferrin from hen egg white at higher productivity. The present work provides a new alternative for membrane chromatography of biomacromolecules.