Fluorescence Probe Based on Graphene Quantum Dots for Selective, Sensitive and Visualized Detection of Formaldehyde in Food

Graphene quantum dots (GQDs) have been successfully used as a highly sensitive probe for the sensing of formaldehyde (HCHO) in an aqueous solution. Through static quenching, the probe utilizes the interaction between HCHO and GQDs to trigger the “turn off” fluorescence response, and has good selectivity. The probe can detect HCHO in a pure aqueous solution, and it also can still detect HCHO in a complex environment with a pH range from 4 to 10. The concentration of HCHO and the fluorescence intensity of GQDs show a good linear relationship within the range of HCHO of 0–1 μg/mL, which was much more sensitive than previous reports. The limit of HCHO detection by GQDs is about 0.0515 μg/mL. In addition, we successfully applied it to the actual food inspection. It is proved to be a selective, sensitive and visualized method to check whether the concentration of HCHO in the foods exceeds the regulatory limit, which presents a potential application in food safety testing.

Tannin-based extracts of Mimosa tenuiflora bark: features and prospecting as wood adhesives

Mimosa tenuiflora (Willd.) Poir. (MT) is an underutilized plant specie since its wood is mostly used for energy production. Nonetheless, the bark from this forest plant has a high amount of tannins and other valuable compounds. Tannins have high worldwide importance and, because of that, there is an increasing number of researches on biorefinery systems aiming at maximizing their exploitation. The present study evaluated tannins extracted from the MT bark and their use for producing wood adhesives. Three types of powdered tannins were extracted using different solvents: a pure aqueous solution, a 5% sodium hydroxide (NaOH) aqueous solution, and a 5% sodium bisulfite (NaHSO3) aqueous solution. Distilled water, wheat flour, and formaldehyde were also used as a solvent, a glue extender, and a catalyst, respectively. These adhesives were applied for bonding pine wood joints and their shear strengths were determined. All the MT-based adhesives showed high viscosities and, yielded glue lines with similar shear strengths and similar shear deformations if compared to each other. That tannin-based glue incorporated with the tannin extracted using NaOH or NaHSO3 stood out and yielded similar bonding performances if compared to a commercial adhesive applied as a positive control.

An “off–on–off” fluorescence chemosensor for the sensitive detection of Cu2+ in aqueous solution based on multiple fluorescence emission mechanisms

A new type of fluorescent chemical sensor (AHBH-PMOs) with AIE and ICT mechanisms is synthesized, which can detect copper ions in pure aqueous solution with good selectivity and high sensitivity.

Nucleation control and separation of vanillin polymorphs I and II through the swift cooling crystallization process

Stable form-I and metastable form-II polymorphs of vanillin are identified through morphology and separated in terms of supersaturation ranges from pure aqueous solution without the use of nucleation selecting materials.

Tannin-Based Extracts of Mimosa Tenuiflora Bark: Features and Prospecting as Wood Adhesives

Mimosa tenuiflora (Willd.) (MT) Poir. is an underutilized plant specie since its wood is mostly used for energy production. Nonetheless, the bark from this forest plant has a high amount of tannins and other valuable compounds. Tannins have high worldwide importance and, because of that, there is an increasing number of researches on biorefinery systems aiming at maximizing their exploitation. The present study evaluated tannins extracted from the MT bark and their use for producing wood adhesives. Three types of powdered tannins were extracted using different solvents: a pure aqueous solution, a 5% sodium hydroxide (NaOH) aqueous solution, and a 5% sodium bisulfite (NaHSO3) aqueous solution. Also, distilled water, wheat flour, and formaldehyde were used as a solvent, a glue extender, and a catalyst, respectively. These adhesives were applied for bonding pine wood joints and their shear strengths were determined. All the MT-based adhesives showed high viscosities and, if compared to each other, yielded glue lines with similar shear strengths and similar shear deformations. That tannin-based glue incorporated with the tannin extracted using NaOH/NaHSO3 stood out and yielded a similar bonding performance compared to a commercial adhesive applied as a positive control.

An efficient water-soluble fluorescent chemosensor based on furan Schiff base functionalized PEG for the sensitive detection of Al3+ in pure aqueous solution

An efficient reversible fluorescent chemosensor, PEGFB, based on polyethylene glycol bearing a furan Schiff base unit has been successfully developed to sensitively detect Al3+ in pure aqueous solution.

A Highly Selective Turn-on and Reversible Fluorescent Chemosensor for Al3+ Detection Based on Novel Salicylidene Schiff Base-Terminated PEG in Pure Aqueous Solution

The development of highly selective and sensitive chemosensors for Al3+ detection in pure aqueous solution is still a significant challenge. In this work, a novel water-soluble polymer PEGBAB based on salicylidene Schiff base has been designed and synthesized as a turn-on fluorescent chemosensor for the detection of Al3+ in 100% aqueous solution. PEGBAB exhibited high sensitivity and selectivity to Al3+ over other competitive metal ions with the detection limit as low as 4.05 × 10−9 M. PEGBAB displayed high selectivity to Al3+ in the pH range of 5–10. The fluorescence response of PEGBAB to Al3+ was reversible in the presence of ethylenediaminetetraacetic acid (EDTA). Based on the fluorescence response, an INHIBIT logic gate was constructed with Al3+ and EDTA as two inputs. Moreover, test strips based on PEGBAB were fabricated facilely for convenient on-site detection of Al3+.

A near-infrared fluorescent probe for the discrimination of cysteine in pure aqueous solution and imaging of cysteine in hepatocellular carcinoma cells with facile cell-compatible ability

A NIR fluorescence sensor for selectively detecting cysteine in aqueous solution with fast response and long emission wavelength was synthesized.

A nucleic acid cleavage-based fluorescent probe for the detection of copper ions in pure aqueous solution

Herein, a novel carbazole derivative of BEVC was designed with an enhanced fluorescence signal by a G-quadruplex, and thus a fluorescent probe of G-quadruplex/BEVC was obtained by aggregation-induced emission, which could exhibit a decreased fluorescence signal in the presence of Cu2+via the Fenton reaction, demonstrating great potential for Cu2+ assay in pure aqueous solution.