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Aluminum foil as a substrate for metal enhanced fluorescence of bacteria labelled with quantum dots, shows very large enhancement and high contrast
摘要： Very high surface/metal enhanced fluorescence was observed for E. coli single bacteria cells labeled with composite CdSeS/ZnS quantum dots (QDs) on three substrates: aluminum foil, aluminum film and gold film. The enhancement factors relative to maximum fluorescence intensity on glass for those substrates were in the range of several hundred (up to 500) for two-excitation wavelengths 532 and 633 nm. Contrast as a ratio of signals from QD labeled to signals of QD unlabeled (control) cells was also in the range of 100 s for those substrates and the highest contrast of 370 was observed on Al film. When CdTe QDs were used for labelling cells on all substrates or when fluorescence from cells with both QDs was measured on silver film, low or no enhancement was observed. Overall, untreated aluminum foil demonstrated great potential as low-cost substrate for surface/metal enhanced fluorescence, which delivers even more reproducible signal than gold film.
关键词： E. coli,Bacteria,Enhancement facor,Quantum dots,Single bacterial cell detection,Metal enhanced fluorescence,Contrast,Surface enhanced fluorescence,Aluminum foil,QD toxicity
更新于2025-09-23 15:21:01
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Optimization and Comparison between the efficiency of GaNAsSb and GaInNAs single solar cells deposed on GaAs
摘要： In this work we study and optimize the single solar cell efficiency of GaNxAs1-x-ySby and Ga1-xInxNyAs1-y deposed on GaAs. The solar cells are simulated, in the aim to find the best concentration of nitrogen and antimony for GaNxAs1-x-ySby, and indium and nitrogen for Ga1-xInxNyAs1-y which gives us a band gap energy around 1 eV with a low strain and a maximum absorption, in fact we do not have only one value but a whole interval for both structures. In the second step we simulate the efficiency of both GaNAsSb and GaInNAs solar cells with the find concentration values in order to see which of the two structures will give a higher efficiency. We noticed that the results were obtained under AM1.5 illumination, 300 K and an ambient pressure. The two structures had a thickness of 300 nm. The N and P layers have a doping level of 1.1015 cm-3 and 1.1016 cm-3 respectively. This study gives us the possibility to produce multi-function solar cells.
关键词： Solar Cell,Detection,New Materials,Semiconductor III-V
更新于2025-09-12 10:27:22
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Centroid tracking and velocity measurement of white blood cell in video
摘要： Automated blood cells tracking system has a vital role as the tracking process reflects the blood cell characteristics and indicates several diseases. Blood cells tracking is challenging due to the non-rigid shapes of the blood cells, and the variability in their videos along with the existence of different moving objects in the blood. To tackle such challenges, we proposed a green star based centroid (GSBC) moving white blood cell (WBC) tracking algorithm to measure its velocity and draw its trajectory. The proposed cell tracking system consists of two stages, namely WBC detection and blob analysis, and fine tuning the tracking process by determine the centroid of the WBC, and mark the centroid for further fine tracking and to exclude the bacteria from the bounding box. Furthermore, the speed and the trajectory of the WBC motion are recorded and plotted. In the experiments, an optical flow technique is compared with the proposed tracking system showing the superiority of the proposed system as the optical flow method failed to track the WBC. The proposed system identified the WBC accurately, while the optical flow identified all other objects lead to its disability to track the WBC.
关键词： Trajectory analysis,Video processing,Cell detection,Velocity measurements,Blob analysis,White blood cell,Tracking system
更新于2025-09-10 09:29:36
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Two-dimensional porphyrin-based covalent organic framework: A novel platform for sensitive epidermal growth factor receptor and living cancer cell detection
摘要： A porphyrin-based covalent organic framework (denoted as p-COF) was synthesized by a simple oil-bath method and exploited as a novel sensing layer for immobilizing epidermal growth factor receptor (EGFR)-targeting aptamer strands to detect trace EGFR and living michigan cancer foundation-7 (MCF-7) cells for the first time. p-COF presented a nanosheet-like structure, large cavities, rich nitrogen-bearing groups, high electrochemical activity, excellent bioaffinity, low toxicity, and good stability in aqueous solution; the microstructural features of this material enabled strong immobilization of the aptamer strands. Interactions between the aptamer strands and EGFR significantly changed the electrochemical signals of the modified electrode due to the formation of an aptamer-EGFR complex. The p-COF-based aptasensor exhibited an extremely low detection limit (LOD) of 5.64 fg?mL?1 obtained from differential pulse voltammetry and 7.54 fg?mL?1 originated from electrochemical impedance spectroscopy with a broad linear detection range of 0.05–100 pg?mL?1 of the EGFR concentration. When detecting living MCF-7 cells, the p-COF-based aptasensor showed an LOD of 61 cell?mL?1 with a linear detection range of 500 × 105 cell?mL?1. The fabricated aptasensor exhibited high selectivity, good stability, reproducibility, acceptable recyclability, and favorable applicability in human serum samples. We believe that the developed p-COF-based aptasensor is a potential candidate for the sensitive detection of target cancer markers or living cells.
关键词： Detection of epidermal growth factor receptor,Living cancer cell detection,Porphyrin-based covalent organic framework,Electrochemical aptasensor
更新于2025-09-09 09:28:46