Significant levels of infectious diseases caused by pathogenic bacteria are nowadays a worldwide concern implying considerable public healthcare challenges and huge economic detriment. Due to the fast spread of these bio-threat agents and the outbreak of diseases, a rapid detection of pathogens at early stages is crucial, particularly in low-resource settings. To this aim, we developed for the first time a new sensing approach carried out in a single-step for Escherichia coli O157:H7 detection. The detection principle is based on Förster Resonance Energy Transfer using gold nanoclusters as signal reporter and gold nanoparticles conjugated with antibodies as a quencher. The sensing platform includes and UV-LED to provide the proper excitation and consists in a microtube containing two pieces of fiber glass; one of them is embedded with label-free gold nanoclusters and the other one with gold nanoparticles conjugated with antibodies. Upon the addition of the sample containing bacteria the florescence of gold nanoclusters is recovered. The assay was evaluated by naked eye (on/off) and quantitatively using a smartphone camera. The biosensor proved to be highly specific and sensitive, achieving a limit of detection as low as 4.0 CFU ml -1 . Additionally, recoveries of 110% and 95% were obtained when evaluating the platform in spiked river and tap water respectively.
Background:
Isatin (1H-indole-2,3-dione) and its derivatives have been shown their responsibility in a wide range of biological activities. Among the range of beneficial properties, anticancer compounds were the most extensively highlighted and explored.
Objective:
Herein, we report the targeting effect of halogenated isatin derivatives on cancer cell mitochondria and their antiproliferative mechanism.
Method:
A series of novel 5-halo-Isatin derivatives consisting 5-Amino-1,3,4-thiadiazole-2-thiol scaffold were synthesized and easily conducted in good yields through a condensation reaction between keto groups of Isatin and primary amine under alcoholic conditions, followed by S-benzylation. The compounds were fully characterized using spectroscopic methods such as 1H-NMR, FTIR, mass spectroscopy and then tested in vitro towards three cancer cell lines HT-29 (colon cancer), MCF-7 (breast cancer) and SKNMC (neuroblastoma). Apoptosis induction was investigated through assessment of caspase 3 and mitochondrial membrane potential.
Results:
The most potent compounds of 5b, 5r (IC50 = 18,13 µM) and 5n (IC50 = 20,17 µM) were found to show strong anticancer activity, especially for MCF7 cells. Further anticancer mechanism studies indicated that 5b and 5r induced apoptosis through the intrinsic mitochondrial pathway.
Conclusion:
This research demonstrated that 5b and 5r have an anticancer property via the modulation of oxidative stress-mediated mitochondrial apoptosis and immune response, which deserves further studies on their clinical applications.
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