Fluorometric turn-on detection of ascorbic acid based on controlled release of polyallylamine-capped gold nanoclusters from MnO2 nanosheets

MnO2-DNA nanomaterials toward the dual signal detection of P-aminophenol micropollutants

P-Aminophenol (PAP), a potentially toxic and mutagenic compound, is widely distributed in water and soil and has serious side effects on human health. This study presents a convenient, sensitive, and effective dual-signal assay for the detection of PAP in the environment. Two-dimensional manganese dioxide (MnO₂) nanosheets were used as the carrier and quencher for fluorophore-labelled DNA to form a dual-signal nanoprobe, MnO₂-DNA. Based on a specific redox reaction between the MnO₂ nanosheets and target PAP, the corresponding absorption intensity of the product and the fluorescence intensity were both "turn-on" and also exhibited excellent correlation with the concentration of PAP. This strategy not only remarkably simplifies the detection process but also improves the reliability of results due to the dual-signal response, which has promising applications in environmental, clinical, and industrial research fields.

Carbon dots for ratiometric fluorescence detection of morin

The B,N dual-doped carbon dots (B,N-CDs) for ratiometric fluorescence detection the morin were prepared from sodium tetraborate and polyethyleneimine through the single-step hydrothermal method. The B,N-CDs exhibited the optimum excitation and emission wavelength at 340 nm and 467 nm, respectively. Interestingly, the intensities of emission peak at 467 nm of B,N-CDs reduced meanwhile a new peak emerged at 560 nm with the continuous addition of morin, which revealed the ratio fluorescence characteristic between F_560nm/F_467nm and morin concentration with the linearity range and detection limit of 14.5-32.5 μmol/L and 0.3 μmol/L (S/N = 3), respectively. The interference of common antibiotics and remedies could be ignored when the concentration of morin was detected by the B,N-CDs, which demonstrating the outstanding selectivity. Furthermore, the proposed fluorescence method is used to detect morin in urine with recoveries are 99.8-104.5%. The results of this research indicate the feasibility and practicality of B,N-CDs as an effective fluorescent probe for the determination of morin.

An OliGreen-responsive fluorescence sensor for sensitive detection of organophosphorus pesticide based on its specific selectivity towards T-Hg2+-T DNA structure

In this paper, it was found that OliGreen emitted much stronger fluorescence in rigid T-Hg²⁺-T DNA structure than that in the presence of poly T. Thus, an OliGreen-responsive label-free fluorescent sensor was proposed for sensitive detection of organophosphorus pesticides (OPs) by constructing T-Hg²⁺-T DNA structure. OliGreen emits strong fluorescence in T-Hg²⁺-T structures. The rigid DNA structure of T-Hg²⁺-T is prone to be destroyed by thiocholine (TCh) that hydrolyzed by acetylcholinesterase (AChE) because of the high affinity of TCh with Hg²⁺. As a result, T-Hg²⁺-T DNA structure broke down and the fluorescence intensity of OliGreen decreased greatly. With the inhibition of AChE by OPs, fluorescence intensity of OliGreen remained strong because of the rigid T-Hg²⁺-T DNA structure. Thus, a "turn-on" fluorescent sensor which avoids synthesis of nanomaterials and complex label procedures is proposed based on the fluorescence intensity of OliGreen. DDVP were detected with a wide linear range from 0.005 to 25.0 ng/mL and the detection limit was 2.9 pg/mL, which is more sensitive than previously reported methods.

A nopinone based multi-functional probe for colorimetric detection of Cu2+ and ratiometric detection of Ag. Photochem Photobiol Sci 2020;19:49-55. [PMID: 31793618 DOI: 10.1039/c9pp00297a]

A dual-signal probe PPN based on the natural β-pinene derivative nopinone was synthesized for the colorimetric detection of Cu2+ and ratiometric detection of Ag+. Upon the addition of Ag+, a significant fluorescence change from blue to green was observed with a low detection limit (0.86 μM). However, upon the addition of Cu2+, a significant color change from colorless to yellow was observed with a low detection limit (0.56 μM). The novel probe PPN was applied as a probe for the colorimetric detection of Cu2+ and ratiometric detection of Ag+ with a high selectivity, good sensitivity and fast response time. The detection mechanisms of probe PPN for Cu2+/Ag+ were confirmed by 1H NMR and HRMS-ESI. Besides, probe PPN could sense Cu2+/Ag+ on test strips. Additionally, probe PPN could be applied to quantitatively detect the concentration of Ag+ in water samples and image Ag+ in living cells.

Polymeric template assisted synthesis of monodisperse-porous manganese oxide microspheres: a new nanozyme with oxidase-like activity allowing biomolecule determination via bimodal sensing

New template assisted synthesis of monodisperse-porous MnO₂ microspheres and their usage as a nanozyme in the first bimodal sensing of ascorbic acid.