A composite consisting of bromine-doped carbon dots and ferric ions as a fluorescent probe for determination and intracellular imaging of phosphate.

A composite probe has been developed for fluorometric determination and imaging of phosphate in real water samples and in cells. The method is based on the use of weakly blue fluorescent bromine-doped carbon dots (C-dots) containing aromatic carbon-bromine groups and loaded with Fe3+ ions. The carboxy, phenolic hydroxy and aldehyde groups on the surface of the C-dots can coordinate with Fe3+ to form an adsorbed complex that reduces the blue fluorescence through an inner filter effect. If phosphate is added, it will capture Fe3+ on the surface of C-dots and restore fluorescence by ~88% via a displacement approach. The probe, best operated at excitation/emission maxima of 370/418 nm, has a linear response in the 0.4 to 22 µM phosphate concentration range and a 0.25 µM of detection limit. The relative standard deviation (at a phosphate level of 8.0 µM) is 3.6% (for n = 5). The method was applied to confocal imaging of phosphate in HeLa cells. Graphical abstractSchematic representation of the synthesis of bromine-doped carbon dots (C-dots) by a "one-step" approach. They are shown to be capable of (a) detecting phosphate in real water samples through the displacement approach, and (b) of imaging intracellular phosphate.

Analgesic activity of the aqueous fraction from the ethanolic extract of Chrysanthemum indicum in mice.

The aqueous fraction (AF) of an ethanolic extract from Chrysanthemum indicum was evaluated for analgesic activity in mice using chemical and thermal models of nociception. Given orally, AF at doses of 300 and 600 mg/kg produced significant inhibitions on chemical nociception induced by intraperitoneal acetic acid, subplantar formalin/capsaicin injections and on thermal nociception in the tail-flick test and in the hot plate test. In the pentobarbital sodium-induced sleeping time test and the open-field test, AF neither significantly enhanced the pentobarbital sodium-induced sleeping time nor impaired the motor performance, indicating that the observed analgesic activity was unlikely due to sedation or motor abnormality. In a measurement of core body temperature, AF did not affect temperature within 80 min. Moreover, the effective dose (600 mg/kg) also showed no toxicity within 7 days. These results suggested further that AF produced analgesic activity possibly related to the flavonoid glycosides and phenolic glycosides in this fraction.