We have successfully prepared a highly sensitive sandwich nanosensor combined Fe 3 O 4 and [email protected] @Ag nanorods for histamine detection based on surface-enhanced Raman spectroscopy (SERS). The Fe 3 O 4 beads with –COOH served as a capture part to enrich histamine. The [email protected] @Ag core-shell nanorods functionalized with Nalpha,Nalpha-Bis(carboxymethyl)- l -lysine (AB-NTA) were then used to connect with the imidazolyl group of histamine, simultaneously the internal standard 4-aminothiophenol (4-ATP) in the core-shell structure was used as the SERS signal. PLS regression model based on concentration range 10 −3 -10 −8 mol/L showed a linear trend with R 2 = 0.9907. Our new approach can quickly and reliably determine histamine in fish sample and RAW264.7 cell lysates. This protocol for histamine extraction and SERS analysis enables the development of ultra-sensitive method for histamine detection.
As a wastewater treatment technology, the activity of advanced oxidation process (AOPs) is strongly dependent on pH value. Herein, considering the low activity of AOPs under alkaline conditions, the acid organic ligand (nitrilotriacetic acid, NTA) was chosen to design Co-NTA metal-organic catalyst for efficient photo-Fenton reaction at full pH range. The experimental results indicate the acid ligands in Co-NTA offers more·OH that can achieve high activity under alkaline conditions. To further enhance the electron injection ability and redox cycles of Co(II)/Co(III), Ferrocene (Fc) nanoparticles was introduced to form bimetallic organic catalyst Fc-Co-NTA. The mechanism study indicates that the synergistic effect between Co-NTA and Fc promotes the activation of potassium persulfate and improves the stability of the catalyst under extreme pH conditions, while the π-π interaction between TC and Fc-Co-NTA can improve the electron injection capability and accelerate the production of·OH/SO 4 •- , so as to accelerate the redox cycles of Fe(II)/Fe(III) and Co(II)/Co(III), bringing about prolonged carrier lifetime and better photocatalytic activity. The possible degradation pathway of TC was investigated by Fukui function and LC-MS. A machine learning model is used to optimize the synthesis and photocatalytic parameters of Fc-Co-NTA. This study provides a new design idea to prepare highly efficient and stable photo-Fenton advanced oxidation technology at full pH range.
A novel Eu-containing SBA-15 mesoporous hybrid material with multicolor emission modulated by fluoride ion was synthesized. First, the organic ligand 1-(2-naphthoyl)-3,3,3-trifluoroacetonate (NTA) was modified by the silane coupling agent 3-(triethoxysilyl)propylisocyanate to form an alkene precursor (NTA-Si), which was covalently grafted onto a mesoporous SBA-15 backbone through co-hydrolysis and co-condensation reactions; as a result, mesoporous hybrid NTA-S15 was obtained. 2-(2-Carboxylphenyl)-imidazo[4,5-f]-1,10-phenanthroline (L) was used as the second ligand, whose two pyridine N atoms coordinate with europium ions and sensitize the luminescence of Eu3+, and the NH group of the imidazole ring and –COOH group formed hydrogen bonds with fluoride ions. Finally, after the coordination reaction between Eu3+ and the organic ligands (NTA-S15 and L), the mesoporous hybrid material Eu(NTA-S15)3L was obtained. Fourier transform infrared, small-angle X-ray diffraction, N2 adsorption measurements, transmission electron microscopy, and scanning electron microscopy were performed, and photoluminescence spectra and thermogravimetric plots were characterized. The results show that Eu(NTA-S15)3L displays a high surface area, uniform mesostructure, good thermal stability, and excellent photophysical properties. Furthermore, Eu(NTA-S15)3L exhibits a highly sensitive sensing function toward the fluoride ion. More importantly, tunable multicolor emissions, which cover nearly the entire visible region, can be readily achieved by varying fluoride ion concentrations under a single-wavelength excitation.
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