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The development of rapid visual detection methods for heavy metal ions is significant for food safety and environmental protection. This work integrated copper nanoclusters and the organometallic framework ZrMOF into a nano detection system. The blue fluorescence of ZrMOF was used as a fluorescent internal standard. The visual and rapid detection of aluminum ions (Al3+) was achieved by Al3+ induced fluorescence enhancement of copper nanocluster aggregates. This nanoprobe has the advantages of high sensitivity, rapid response, and high visualization. The nanoprobe can detect Al3+ with a concentration of 0–60 μM (LOD was 139 nM) and can be used to detect Al3+ in environmental water samples. In addition, an instant detection platform for test paper and gel system based on the nanoprobe was constructed by using the smartphone's colorimetric acquisition and computational analysis application software (APP), which guides the application of multicolor fluorescent nanoprobes in the intelligent detection of fruit surfaces and flour additives. [Display omitted] [ABSTRACT FROM AUTHOR]

Long-term discharge of tetracycline (TC) in the environment exerts selective pressure on the bacteria, increasing resistance in sensitive bacteria and posing a serious threat to public health. Therefore, it is crucial to develop real-time detection of tetracycline. In this study, we reported a novel rare-earth fluorescent nanosensor FITC-GMP-Eu, based on the formation of guanosine-5′-monophosphate disodium salt (GMP) and fluorescein isothiocyanate (FITC), which enabled the real-time identification of tetracycline in the environment. When there was no TC in the environmental sample, the FITC-GMP-Eu nanosensor exhibited the green fluorescence of FITC due to the fluorescence quenching effect of water molecules on Eu3+. When the environmental samples contained TC, the red fluorescence of Eu3+ could be sensitized due to the diketone structure in the tetracycline molecule, which enabled the naked-eye visualized identification of TC. The nanosensor had high sensitivity (detection limit of 19 nM) and a wide detection range (0–30 μM) for TC. At the same time, the sensor was characterized by high visualization and anti-interference ability due to the strong fluorescence of both FITC and Eu complexes. In order to improve the practicality of the detection, this study also prepared a paper-based and sodium alginate gelated fluorescence detection platform with low background fluorescence. Combined with the common color analysis and RGB extraction procedures in mobile phones, real-time and on-site identification of TC on the surface of various fruit samples can be achieved. [Display omitted] • An innovative multicolor fluorescent nano-sensor was elaborately tailored. • The nano-sensor had high sensitivity and a wide detection range for TC. • The paper-based and sodium alginate gelated fluorescence detection platform. • Real-time and intelligent identification of TC on various fruit samples. [ABSTRACT FROM AUTHOR]

In this study, graphene oxide-grafted pyridine-based ionic liquids were prepared and used as novel and highly efficient triphase catalysts for the synthesis of benzyl esters by the nucleophilic substitution reaction of benzyl halide with carboxylic acid salt. The as-prepared catalysts were characterized through several technologies including Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, elemental analysis, atomic force microscopy and thermal gravimetric analysis. The catalysts showed excellent catalytic performances in the synthesis of benzyl esters by the above-mentioned reaction. High conversion of benzyl halide (99%) and selectivity of benzyl ester (97%) were obtained after 6 h at 120 °C over the catalysts. Furthermore, the as-prepared triphase catalysts could be easily recovered and reused at least five times without significant loss of catalytic activity. The amphiphilicity of graphene oxide played an important role in the transfer of carboxylic anions from the aqueous phase to the organic phase, which accelerated the nucleophilic substitution reaction of benzyl halide with carboxylic acid salt. [ABSTRACT FROM AUTHOR]

Multistimuli responsive luminescence material have tremendous potential in various advanced photonic applications, especially in high-level information encryption. Here, a facile and effective way was presented to construct multistimuli intelligent luminescent nanomaterial based on europium modified carbon dots (CDs-Eu) for advanced information encryption. This nanocomposite exhibiting controllable response behaviors upon exposure to acid-base, 2,6-dipicolinic acid (DPA) and Cu2+ hold an enormous potential in multilevel encryption application. The fluorescence (FL) color of CDs-Eu can be reversibly switched between colorless and green upon acid-base stimulation. Furthermore, in the presence of the deciphering agent (DPA), the fluorescence color of CDs-Eu exhibited a green to red color change, which can be restored upon another external stimulus (Cu2+). Combined with Morse code and anti-counterfeiting pattern, the encryption, decryption and anti-counterfeiting of important information can be realized. This stimuli-responsive luminescence material with high confidentiality shows great potential in advanced information encryption. [Display omitted] • A facile and effective way was presented to construct stimuli-responsive smart luminescent material. • The CDs-Eu exhibited controllable color changes upon exposure to acid-base, DPA and Cu2+. • Multilevel encryption and anti-counterfeiting were achieved based on the CDs-Eu. [ABSTRACT FROM AUTHOR]

Thanks to the superior performance and convenience for preparation and operation, programmable memory materials have drawn extensive attention as the ever-higher requirements for anti-counterfeiting. In this work, a lanthanide-doped pH-responsive luminescent sensor (MMT@[Eu(Phen) 2 ]-PFX, MMT = montmorillonite, PFX = pefloxacin) was prepared to achieve reversible multicolor luminescence conversion (from blue to red) by changing the pH of the solution, and thus brought about the designation of a portable test strip for biogenic amines detection. Moreover, multiple encryption and decryption of confidential information can be materialized by combining the sensor with digital code and Morse code. Additionally, the optical memory device MMT@ [Eu(Phen) 2 ]-PFX@CS (CS = chitosan) enabled reversible switching of sol-gel and emission colors synchronously during acid-base conversion. Hence, this smart fluorescent material can be widely applied in the fields of information security and biogenic amines detection for the future. [Display omitted] [ABSTRACT FROM AUTHOR]

Ultrasensitive visual detection of anthrax markers is of great significance for disease prevention and early warning of terrorist attacks. A novel of dual-emission ratiometric fluorescent nano-probe (HNT-CDs-Eu) has been elaborately tailored based on the direct in-situ growth of CDs on natural mineral nanotubes (HNTs) for the determination and visual assay of DPA concentrations, using DTPA as the efficient chelating agent and the raw material for the preparation of CDs. The rich carboxyl groups of DTPA also provide coordination sites for Eu3+ to form highly sensitive recognition groups. This multi-color nano-sensor can not only realize ultra-sensitive trace detection of pure DPA, but also meet the feasibility of visual sensing of DPA in environmental water samples. Since the common filter paper has strong blue fluorescence under ultraviolet light irradiation at 365 nm, a color agarose gel for visual inspection and an advanced analytical device for one-to-two decoder are further prepared to realize the intelligent and real-time detection of DPA. [Display omitted] • An innovative dual-emission ratiometric fluorescent nano-probe was elaborately tailored. • The fabrication included the direct in-situ growth of CDs on natural mineral nanotubes. • This multi-color nano-sensor can realize ultra-sensitive trace detection of DPA in environmental water. • An advanced analytical device based on agarose gel was further prepared and researched. [ABSTRACT FROM AUTHOR]

In this contribution, Pickering emulsion system was prepared by bi-functional graphene oxide (GO) grafted with polyethylene glycol (PEG) and 3-aminopropyltrimethoxysilane (APS), which was used as highly efficient catalyst in place of phase transfer catalyst for aqueous nucleophilic substitution reactions. In this Pickering emulsion system, PEG and APS acted as double active sites, in which APS as Lewis base was firstly demonstrated to have catalytic activity for the aqueous nucleophilic substitution. It is found that Pickering emulsion catalytic system prepared by bi-functional GO has more dense droplets distribution and smaller droplets size compared to that by GO-PEG or GO-APS. It can be inferred that APS as stabilizer of oil in water emulsion and PEG showed good synergy for aqueous nucleophilic substitution reactions. It was found that the properties of Pickering emulsion, including droplets distribution and size, was closely related to catalytic performance for the reactions. As the results, Pickering emulsion system in the optimized reaction conditions could exhibit excellent catalytic performance (yield ≥90%) for the production of iodooctane from bromooctane and NaI without stirring. What's more, the spent Pickering emulsion could be easily reconstructed and show good reusability (yiled ≈80%) even after using for seven times. [ABSTRACT FROM AUTHOR]