Hexagonal Cobalt Oxyhydroxide–Carbon Dots Hybridized Surface: High Sensitive Fluorescence Turn-on Probe for Monitoring of Ascorbic Acid in Rat Brain Following Brain Ischemia

Abstract

In this study, we report a novel and efficient fluorescence probe synthesized by Tris(hydroxymethyl)aminomethane-derived carbon dots (CDs)-modified hexagonal cobalt oxyhydroxide(CoOOH) nanoflakes (Tris-derived CDs-CoOOH) for monitoring of cerebral ascorbic acid (AA) in brain microdialysate. The as-prepared Tris-derived CDs with the fluorescence quantum yield of 7.3% are prepared by a one-step pyrolysis strategy of the sole precursor and used as the signal output. After being hybridized with CoOOH nanoflakes to form Tris-derived CDs-CoOOH, the luminescence of the Tris-derived CDs can be efficiently quenched by CoOOH via fluorescence resonance energy transfer (FRET). Due to the specific redox reaction between the enediol group of AA and hexagonal CoOOH nanoflakes, AA can reduce the hexagonal CoOOH nanoflakes in the Tris-derived CDs-CoOOH and lead to collapse of the hybrized structure, then the release of Tris-derived CDs, and thus finally the fluorescence recovery. Moreover, cobalt ions (II), generated by CoOOH nanoflakes oxidizing AA, almost have no obvious interference on the fluorescence probe, i.e., Tris-derived CDs, which could be ascribed to the surface of Tris-derived CDs containing a few strong chelation groups such as amino/carboxyl/thiol groups, instead of plenty of -OH groups with weak chelation with Co(2+). On the basis of this feature, the Tris-derived CDs-CoOOH fluorescent probe demonstrates a linear range from 100 nM to 20 μM with the detection limit of ∼50 nM, i.e., with an improved sensitivity toward AA detection. Compared with other turn-on fluorescent methods using convenient fluorophore-nitroxide fluorescent probes for detection of AA, the method demonstrated here possesses a facial synthesis route, lower limit of detection, and wider linear range, which validates sensing of AA in the cerebral systems during the calm/ischemia process. This study provides a fluorescence assay for the simple yet facial detection of AA in the cerebral systems and assists in the understanding of the biological processes in the physiological and pathological study.

Specificity and mechanism of action of alpha-helical membrane-active peptides interacting with model and biological membranes by single-molecule force spectroscopy

“…In addition, blocking experiment was used to test the specificity of these force events. As the electrostatic attraction is one important reason for peptides approaching model membranes and biological membranes, the Tris-HCl buffer including plenty amino groups 20 was injected into the working chamber and inhibits the interactions between MAPs and model membranes/biological membranes. We found that most of the interaction force signals of peptides with model membranes and biological membranes disappeared in the force curves ( Fig.…”

Rapid and simple detection of ascorbic acid and alkaline phosphataseviacontrolled generation of silver nanoparticles and selective recognition

“…Consequently, it has received extensive attention. To date, many fluorescence methods were developed for AA and ALP detection using materials, such as carbon dots (CDs), 10 cerium metal-organic frameworks (MOFs), 11 gold nanoclusters (Au NCs), 12 quantum dots (QDs), 13 DNA-templated silver nanoclusters (Ag NCs), 14 poly(thymine)-templated copper nanoclusters (Cu NCs), 15 MnO 2 nanosheets, 16 etc.…”

A GSH-responsive nanophotosensitizer for efficient photodynamic therapy

“…Cobalt oxyhydroxide (CoOOH) nanosheet, a kind of 2D nanomaterial, has been widely used in the biological elds because of its easy preparation, functionalization and high biocompatibility. 27,28 Moreover, CoOOH nanosheets have a large specic surface area, which makes it suitable for drug loading and substrate detection. 29,30 Most importantly, the optical quenching properties of CoOOH makes it an ideal platform for photosensitizer delivery and responsive cancer treatment, which can signicantly reduce the toxicity of photosensitizer before reaching target sites.…”