Role of tea polyphenols in enhancing the performance, sustainability, and catalytic cleaning capability of membrane separation for water-soluble pollutant removal.

Tea polyphenols (TPs), like green tea polyphenol (GTP) and black tea polyphenol (BTP), with phenolic hydroxyl structures, form coordination and hydrogen bonds, making them effective for bridging inorganic catalysts and membranes. Here, TPs were employed as interface agents for the preparation of TPs-modified needle-clustered NiCo-layered double hydroxide/graphene oxide membranes (NiCo-LDH-TPs/GO). The incorporation of porous guest material, NiCo-LDH-TPs, facilitated water channel expansion, enhancing membrane permeability and resulting in the development of high-performance, sustainable catalytic cleaning membranes. The introduction of TPs through coordination weakened the surface electronegativity of NiCo-LDH, promoting a uniform mixed dispersion with GO and facilitating membrane self-assembly. NiCo-LDH-GTP/GO-5 and NiCo-LDH-BTP/GO-5 membranes demonstrated permeances of 85.98 and 90.76 L m-2 h-1 bar-1, respectively, with rejections of 98.73% and 99.54% for methylene blue (MB). Notably, the NiCo-LDH-BTP/GO-5 membrane maintained a high rejection of 97.11% even after 18 cycles in the catalytic cleaning process. Furthermore, the modification of GTP and BTP enhanced MB degradation through PMS activation, resulting in a 0.33% and 0.35% increase in the reaction rate constants of NiCo-LDH, respectively, while reducing metal ion spillover. These findings highlighted the potential of TPs in enhancing the efficiency and sustainability of catalytic cleaning GO membranes for water purification and separation processes.

3D variable Co species carbon foam enhanced reactive oxygen species generation and ensured long-term stability for water purification.

Cobalt (Co) and oxides are the most common catalysts for activating peroxymonosulfate (PMS). However, practical applications of Co-based PMS-advanced oxidation processes are difficult to realize the degradation of the targeted pollutants due to poor yield of reactive oxygen species (ROS) and inaccessible active sites. Here, we designed 3D oxygen vacancy-rich (Vo-rich) variable Co species@carbon foam (CoxOy@CF) via coupling solvent-free and pyrolysis strategies for degrading tetracycline by PMS activation. The kinetic rate of optimized (Co@CoO) CoxOy@CF-1.0 (1.0 presented the molar ratio of Co2+ and 2-methylimidazole) enhanced by an order of magnitude compared to that of ZIFs derivatives (ZIFs-500) (0.073 vs 0.155 min-1) due to the special structure. The flow-through unit maintained over 90% removal within 12 h, which was far better than that of ZIFs-500/PMS system. We used electrochemical analysis, quenching experiment, in-situ FTIR and Raman spectra to further investigate the possible mechanism of the 3D CoxOy@CF-1.0/PMS system. 3D CoxOy@CF-1.0 stimulated the production of the metastable catalyst-PMS* complex obtained O2- as intermediates accompanied by the redox cycling of Co2+/Co3+, which created the dominant ROS (more 1O2) in the presence of Vo, which was completely different for ZIFs-500/PMS with coordinated and dominant radical and non-radical pathways. This study could large-scale generate variable cobalt-based catalysts for enhanced ROS generation, leading the new insight for boosting practical applications.

Strong coupling of super-hydrophilic and vacancy-rich g-C3N4 and LDH heterostructure for wastewater purification: Adsorption-driven oxidation.

Adsorption and wettability are crucial components of catalytic oxidation. To increase the reactive oxygen species (ROS) generation/utilization efficiency of peroxymonosulfate (PMS) activators, defect engineering and 2D nanosheet characteristics were used to regulate electronic structures and expose more active sites. Two-dimensional (2D) super-hydrophilic heterostructure by connecting cobalt species modified nitrogen vacancy-rich g-C3N4 (Vn-CN) and LDH (Vn-CN/Co/LDH) with high-density active sites and multi-vacancies, as well as high conductivity and adsorbability, to expedite ROS generation. The degradation rate constant of ofloxacin (OFX) was 0.441 min-1 via the Vn-CN/Co/LDH/PMS system, which was 1-2 orders greater than in the previous studies. Confirmation of the contribution ratios of various reactive oxygen species (ROS), SO4·- and 1O2 in bulk solution, O2·- on the catalyst surface was the most abundant ROS. The catalytic membrane was constructed utilizing Vn-CN/Co/LDH as the assembly element. The 2D membrane achieved the continuous effective discharge of OFX in the simulated water after 80 h/4 cycles of continuous flowing-through filtration-catalysis. This study provides fresh insights into designing a PMS activator for environmental remediation activated on demand.

Beetle-Inspired Dual-Directional Janus Pumps with Interfacial Asymmetric Wettability for Enhancing Fog Harvesting.

Fog-harvesting devices (FHDs) have been widely explored and applied to alleviate the shortage of fresh water. However, during the fog collection process, how to maintain a balance between fog capture and water removal behaviors to enhance the water collection rate still remains a challenge. Herein, inspired by the Stenocara beetle, we combined a beetle-like Janus surface and the conventional cross-sectional Janus structure together, developed a simple spray-and-dry strategy to obtain three types of biomimetic asymmetric meshes, and explored the working modes for atmospheric fog collection. The surface wettability could be carefully controlled, and various asymmetric meshes with different water transportation behaviors were obtained. Through a detailed study of the fog collection process, we concluded that there existed three main working modes: Janus mode, hybrid mode, and Janus and hybrid mode. It was noted that the dual-directional Janus pump with the Janus and hybrid working mode balanced the fog capture and water removal ability and exhibited the highest water collection rate of 2478.73 mg m-2 h-1, which was 2.61 times more than that of the corresponding superhydrophilic mesh. Furthermore, the prepared dual-directional Janus pump showed superior mechanical durability and antibacterial ability. In general, this work was considered instrumental in the reasonable design of biomimetic asymmetric meshes and could provide references for efficient atmospheric fog harvesting.

Interfacial engineering of vacancy-rich nitrogen-doped FexOy@MoS2 Co-catalytic carbonaceous beads mediated non-radicals for fast catalytic oxidation.

How to accelerate the Fe3+/Fe2+ conversion and fabricate recyclable iron-based catalysts with high reactivity and stability is highly desired yet challenging. Herein, vacancy-rich N@FexOy@MoS2 carbonaceous beads were firstly developed via employing sodium alginate, molybdenum disulfide (MoS2), and Fe-ZIFs through sol-gel self-assembly, followed by in-situ growth and pyrolysis strategies. As expected, A series of characterizations reflected that N@FexOy@MoS2 had high dispersibility and conductivity for fast mass and electron transport, and MoS2 as co-catalyst accelerated the circulation of Fe3+ to Fe2+ that attained 99.4% (0.345 min-1) norfloxacin degradation via PMS activation in a synergistic ''adsorption-driven-oxidation'' process, which much outperformed those of pure MoS2 (32.4%) and N@FexOy powder catalyst (45.3%). Moreover, confined Fe species, graphitic N, pyrrolic N, pyridinic N, and sulfur/oxygen vacancies were found as highly exposed active sites that contributed to the activation of PMS to dominate non-radicals (1O2 and O2·-) and other radicals following a contribution order 1O2 > O2·- > SO4·- > ·OH. More importantly, a fluidized-bed catalytic unit was evaluated and maintained the continuous zero discharge of NX. Overall, this study offered a generally applicable approach to fabricate removable Fe-based catalysts for contaminants remediation.

2D confinement freestanding graphene oxide composite membranes with enriched oxygen vacancies for enhanced organic contaminants removal via peroxymonosulfate activation.

Introducing membrane filtration into advanced oxidation processes to decrease energy and cost consumption has been considered as a promising direction in environmental remediation. In this work, we firstly developed a kind of novel lawn-like Fe2O3@Co0.08Fe1.92@nitrogen-doped reduced graphene oxide@carbon nanotube composites (FeCo@GCTs) through in-situ pyrolysis of self-assembly of Prussian blue analogues and GO, followed through a vacuum-assisted filtration strategy to fabricate 2D confinement freestanding GO composite membrane. Electrochemical analysis and H2-TPR revealed the superiority of FeCo@GCTs as ideal electron acceptor, and this unique lawn-like structure concentrated active sites with a confined space and enriched oxygen vacancies that realized 98.5% (0.128 min-1) sulfamethoxazole degradation via peroxymonosulfate activation, and accelerated the reduction of Cr(VI). Owing to the increasing interlayer spacing of GO nanosheets, the permeation flux of FeCo@GCTs/GO membrane has not only been attained to 487.3 L·m-2·h-1·bar-1, which was more than 7.5-fold of GO membrane (64.6 L·m-2·h-1·bar-1), but also achieved the synergistic membrane filtration and catalytic degradation of pollutants. Furthermore, scavenger experiments and EPR tests were conducted to confirm the active radicals, of which SO4·- and 1O2 were responsible for SMX degradation. Therefore, these features demonstrated great potential for the fabricated 2D confinement catalytic membrane with enriched oxygen vacancies in wastewater purification.

Hollow molecularly imprinted fluorescent sensor using europium complex as functional monomer for the detection of trace 2,4,6-trichlorophenol in real water samples.

As an important environmental indicator, 2,4,6-trichlorophenol (2,4,6-TCP) was proved extremely harmful to human body. In this article, hollow molecularly imprinted fluorescent polymers (@MIPs) for the selective detection of 2,4,6-TCP were devised and fabricated by sacrificial skeleton method based on SiO2 nanoparticles. As the most innovation, highly luminescent europium complex Eu(MAA)3phen played the role of both fluorophores and functional monomers of the MIPs. The obtained @MIPs showed monodispersity and the average particle size was around 130 nm. It had a linear fluorescent response within the concentration range 10-100 nmol L-1 with the correlation coefficient calculated as 0.99625, and the limit of detection was identified as 2.41 nmol L-1. The results show that Eu(MAA)3phen as a fluorophore has high luminescent properties, and as a functional monomer, it can improve the selectivity and anti-interference performance of MIPs. Furthermore, the hollow structure made it possible that the imprinted specific recognition sites distributed on both inner and outer surfaces of @MIPs. The experimental results showed that these @MIPs could be employed to the selective detection of chlorophenols under low concentration. And this work will provide a reference for further optimization of fluorescent imprinted sensors.

Investigation of catalytic self-cleaning process of multiple active species decorated macroporous PVDF membranes through peroxymonosulfate activation.

Currently, carbon-based catalysts integrated with macroporous catalytic membrane have aroused considerable attention for environmental remediation because of its practicability and high efficiency. Herein, nitrogen doped carbon nanotube hybrids (Fe-Co@NC-CNTs) decorated with multiple active species (Fe3Co7/CoFe2O4@Fe/CoNC) were designed through N-molecule assisted pyrolysis of bimetallic (Fe/Co) metal-organic frameworks, and then immobilized on poly(vinylidene fluoride) (PVDF) membrane to construct macroporous Fe-Co@NC-CNTs/PVDF catalytic membrane via directional freezing technique, where active sites were efficiently exposed for oxidants and target pollutants. As expected, Fe-Co@NC-CNTs/PVDF membrane successfully achieved almost 100% bisphenol A (BPA) degradation after 40 min via PMS activation, which was significantly overperformed the majority of conventional carbon-based catalysts. Besides, we found that Fe-Co@NC-CNTs/PVDF membrane not only exhibited ideal catalytic and self-cleaning property in humic acid (HA)-BPA coexistence system, but also maintained the excellent reusability and ultrahigh water flux (10464.45 L m-2 h-1) even after 5 cycles. Notably, in EPR analysis and quenching experiments, it was found that sulfate radicals (SO4·- and ·OH) and singlet oxygen (1O2) participated the degradation process while 1O2 made a major contribution. More significantly, this study is very meaningful for the development of novel catalytic self-cleaning membranes with PMS activation.

Coordination-driven interfacial cross-linked graphene oxide-alginate nacre mesh with underwater superoleophobicity for oil-water separation.

Inspired by the seashell nacre and seaweed, a novel GO-Ca2+-SA nacre-inspired hybrid mesh was prepared via an interfacial layer-by-layer self-assembly and cross-linking, using graphene oxide (GO) and sodium alginate (SA) as the building blocks and calcium chloride as the coordination agent, respectively. Hybrid mesh was characterized by FTIR, XPS, XRD, SEM and contact angel instrument, showing superhydrophilic and underwater superoleophobic property and low oil adhesion, due to its wrinkle and rough surface, and high hydration ability of GO-Ca-alginate nanohydrogels. The separation efficiencies of various oil-water mixtures were above 99 %, with a highest flux of 119,426 L m-2 h-1. Hybrid mesh showed an orderly layered "brick and mortar" microstructure with many ultrasmall nanoscaled protuberances. Ca2+ ions could chelate with SA to form the "egg-box" structure, and interact with GO nanosheets. Hybrid mesh possessed high salt/acid/alkaline tolerance, abrasion resistance, mechanical property with Young's modulus of 35.8 ± 4.9 GPa, and excellent cycling stability.

Synergistic multiple active species for catalytic self-cleaning membrane degradation of persistent pollutants by activating peroxymonosulfate.

Recently, the development of dual functional catalytic membrane for the synergistic degradation and filtration of persistent pollutants has attracted considerable attention in environmental remediation. Herein, novel CoFe alloy and CoFe2O4 nanoparticles encapsulated in N-doped microtube composites (CoFe-NMTs) were firstly fabricated through in-situ pyrolysis of simple-source Prussian blue analogues (PBA). As expected, this unique structure not only inhibited the nanoparticles agglomeration, but also provided a "highway" that accelerated the Co3+/Co2+ and Fe3+/Fe2+ redox cycles. Therefore, CoFe-NMT-800 (0.1 g/L, pyrolyzed at 800 °C) achieved over 90% tetracycline (TC, 30 mg/L, 0.1821 min-1) removal after 30 min at a wide pH (2.55-9.55) by coupling with peroxymonosulfate (PMS, 0.3 g/L), which dramatically outperformed the majority of the reported catalysts (such as Co3O4, CoFe alloy, CoFe2O4 and N-doped carbon nanotubes, etc.). Additionally, CoFe-NMTs-800 also exhibited excellent catalytic activity in the existence of inorganic anions (Cl-, HCO3- and H2PO4-) and natural organic matters (humic acid (HA)). Subsequently, CoFe-NMTs-800 was immobilized into polyvinylidene fluoride (PVDF) membrane as catalytic self-cleaning membrane via applying phase-inversion technology. It was found that CoFe-NMTs-800/PVDF membrane not only maintained high removal efficiency for TC degradation (over 90%) in TC/HA coexistence system, but also effectively eliminated the adverse effect of membrane fouling. Besides, the fabricated membrane also showed desirable reusability and neglectable metal leaching (0.003 mg/L Fe and 0.015 mg/L) with almost constant flux after five cycles. The quenching experiments and electron paramagnetic resonance (EPR) results clearly indicated that sulfate radicals (SO4-), hydroxyl radicals (OH and singlet oxygen (1O2) were responsible for TC degradation and SO4- was a major contributor. Significantly, this work was very meaningful to construct novel catalytic self-cleaning membrane for water purification.

Robust Nacrelike Graphene Oxide-Calcium Carbonate Hybrid Mesh with Underwater Superoleophobic Property for Highly Efficient Oil/Water Separation.

Inspired by the mastoid structure of the lotus leaf and the robust layered structure of the nacre, a novel nacrelike graphene oxide-calcium carbonate (GO-CaCO3) hybrid mesh with superhydrophilic and underwater superoleophobic property was prepared for the first time, via a facile, economical, and environmentally friendly layer-by-layer (LBL) self-assembly method using commercially available stainless steel mesh (SSM) as a ready-made mask. Interestingly, GO nanosheets played a threefold role, regulating the growth of CaCO3 nanocrystals between the GO interlamination for constructing a "brick-and-mortar" structure, improving the interface stability via coordination assembly onto SSM, and creating strong hydration derived from rich oxygen-containing functional groups. The surface hydrophilicity and hierarchically micro/nanoscale structure of GO-CaCO3 artificial pearls imbed on the SSM, contributing to outstanding superhydrophilicity and underwater superoleophobicity. The biomimetic hybrid mesh exhibited a strong mechanical property with a Young's modulus of 25.4 ± 2.6 GPa. The optimized hybrid mesh showed a high separation efficiency of more than 99% toward a series of oil/water mixtures with high flux. The low oil-adhesion force, high fatigue-resistance, chemical stability (acid/alkali/salt resistance), and excellent recycling performance enlighten the great prospects of GO-based nacrelike material for application in oily wastewater treatment.

Optical Recognition of Sulfamethoxazole by a Colored Chiral Nematic Imprinted Film.

In this article, an alterable structural color in the reflected light of a chiral nematic imprinted film was fabricated. Bio-template nanocrystalline celluloses were applied as structural oriented templates. Selectivity of the sensor was endowed by the molecular imprinting process which applied sulfamethoxazoles (SMXs) as template molecules, urea and phenol as double functional monomers, and formaldehyde as cross-linkers. The sensor exhibited a chiral nematic blue mesoporous structure, which could selectively recognize SMXs on account of the abundant predetermined rebinding sites. Once SMXs were detected, the sensor showed a visible color variance from blue to yellow and the sensitive concentration range was from 3.9 × 10-3 to 3.9 mmol L-1. Both quantitative analyses, selective testing and recycling performance of the sensor were demonstrated. This optical response to SMXs can provide a portable, low-cost and easy-to-use strategy for the convenient detection of SMXs.

Molecularly Imprinted Fluorescent Test Strip for Direct, Rapid, and Visual Dopamine Detection in Tiny Amount of Biofluid.

Paper-based assays for detection of physiologically important species are needed in medical theranostics owning to their superiorities in point of care testing, daily monitoring, and even visual readout by using chromogenic materials. In this work, a facile test strip is developed for visual detection of a neurotransmitter dopamine (DA) based on dual-emission fluorescent molecularly imprinted polymer nanoparticles (DE-MIPs). The DE-MIPs, featured with tailor-made DA affinity and good anti-interference, exhibit DA concentration-dependent fluorescent colors, due to the variable ratios of dual-emission fluorescence caused by DA binding and quenching. By facile coating DE-MIPs on a filter paper, the DA test strips are obtained. The resultant test strip, like the simplicity of a pH test paper, shows the potential for directly visual detection of DA levels just by dripping a tiny amount of biofluid sample on it. The test result of real serum samples demonstrates that the DA strip enables to visually and semiquantitatively detect DA within 3 min by using only 10 µL of serum samples and with a low detection limit ((100-150) × 10-9 m) by naked eye. This work thus offers a facile and efficient strategy for rapid, visual, and on-site detection of biofluids in clinic.

Direct Detection of Potential Pyrethroids in Yangtze River via an Imprinted Multilayer Phosphorescence Probe.

A novel tailored multilayer probe for monitoring potential pyrethroids in the Yangtze River was proposed. The room-temperature phosphorescence method was applied to realize a detection strategy that is superior to the fluorescence method. Efficient Mn-doped ZnS quantum dots with uniform size of 4.6 nm were firstly coated with a mesoporous silica to obtain a suitable intermediate transition layer, then an imprinted layer containing bifenthrin specific recognition sites was anchored. Characterizations verified the multilayer structure convincingly and the detection process relied on the electron transfer-induced fluorescence quenching mechanism. Optional detection time and standard detection curve were obtained within a concentration range from 5.0 to 50 µmol L-1. The stability was verified to be good after 12 replicates. Feasibility of the probe was proved by monitoring water samples from the Zhenjiang reach of the Yangtze River. The probe offers promise for direct bifenthrin detection in unknown environmental water with an accurate and stable phosphorescence analysis strategy.

A polydopamine-based molecularly imprinted polymer on nanoparticles of type SiO2@rGO@Ag for the detection of λ-cyhalothrin via SERS.

A new method is described for the determination of the pesticide λ-cyhalothrin (LC). It combines SERS detection with molecular imprinting and largely improves selectivity. A multilayer surface imprinted nanocomposite was synthesized in two steps on a nanostructure of type SiO2@rGO@Ag acting as a substrates. Firstly, the surface of the SiO2@rGO@Ag composite was modified with self-polymerized dopamine. Secondly, surface-initiated polymerization was carried out to prepare a molecularly imprinted polymer (MIP) using LC as the template. The use of this SiO2@rGO@Ag-MIP allows for excellent SERS based detection and has high selectivity for LC. The Raman intensity and LC concentration present perfect linear relationship between 10-5 to 10-9 mol L-1 and the detection limit is 3.8×10-10 mol L-1. All the procedures are conducted in aqueous or ethanol solution. Graphical abstract Schematic of a new method for determination of the pesticide λ-cyhalothrin. It combines SERS detection with molecular imprinting and largely improves selectivity. A multilayer surface imprinted nanocomposite was synthesized in two steps on a nanostructure of type SiO2@rGO@Ag acting as a substrates.

Facile preparation of intercrossed-stacked porous carbon originated from potassium citrate and their highly effective adsorption performance for chloramphenicol.

Recently, antibiotics pollution has attracted more interests from many researches which causes potential risks on the ecosystem and human health. Herein, the porous carbons (PCs) was prepared by directly simultaneous carbonization/self-activation of potassium citrate at 750-900°C for chloramphenicol (CAP) removal from aqueous solution. The batch experiments were studied, which indicated that PCs prepared at 850°C, namely PCPCs-850, possessed excellent adsorption ability for CAP with a maximum adsorption amount of 506.1mgg-1. Additionally, PCPCs-850 showed a large BET surface area of 2337.06m2g-1 and microporosity of 89.11% by N2 adsorption-desorption experiment. The Langmuir and pseudo-second-order model could more precisely describe the experimental data. And thermodynamic analysis illustrated that CAP adsorption onto PCPCs-850 was an endothermic and spontaneous process. Importantly, the adsorbent exhibited good stability and regeneration after four times cycles. Based on these excellent performance, it is potential that PCPCs-850 can be used as a promising adsorbent for treating contaminants in wastewater.

Bioinspired synthesis of high-performance nanocomposite imprinted membrane by a polydopamine-assisted metal-organic method.

Significant efforts have been focused on the functionalization and simplification of membrane-associated molecularly imprinted materials, which can rapidly recognize and separate specific compound. However, issues such as low permselectivity and unstable composite structures are restricting it from developing stage to a higher level. In this work, with the bioinspired design of polydopamine (pDA)-assisted inorganic film, we present a novel molecular imprinting strategy to integrate multilevel nanocomposites (Ag/pDA) into the porous membrane structure. The molecularly imprinted nanocomposite membranes were then obtained through an in situ photoinitiated ATRP method by using tetracycline (TC) as the template molecule. Importantly, attributing to the formation of the Ag/pDA-based TC-imprinted layers, largely enhance TC-rebinding capacity (35.41mg/g), adsorption selectivity and structural stability (still maintained 92.1% of the maximum adsorption capacity after 10 cycling operations) could been easily achieved. Moreover, largely enhanced permselectivity performance toward template molecule (the permeability factor ß values were also more than 5.95) was also obtained. Finally, all synthesis methods were conducted in aqueous solution at ambient temperature, which was environmental friendly for scaling up without causing pollution.

Detection of λ-cyhalothrin by a core-shell spherical SiO2-based surface thin fluorescent molecularly imprinted polymer film.

A fluorescent core-shell molecularly imprinted polymer based on the surface of SiO2 beads was synthesized and its application in the fluorescence detection of ultra-trace λ-cyhalothrin (LC) was investigated. The shell was prepared by copolymerization of acrylamide with allyl fluorescein in the presence of LC to form recognition sites. The experimental results showed that the thin fluorescent molecularly imprinted polymer (FMIP) film exhibited better selective recognition ability than fluorescent molecularly non-imprinted polymer (FNIP). A new nonlinear relationship between quenching rate and concentration was found in this work. In addition, the nonlinear relationship allowed a lower concentration range of 0-5.0 nM to be described by the Stern-Volmer equation with a correlation coefficient of 0.9929. The experiment results revealed that the SiO2@FMIP was satisfactory as a recognition element for determination of LC in soda water samples. Therefore this study demonstrated the potential of MIP for the recognition and detection of LC in food.

Highly-controllable imprinted polymer nanoshell at the surface of silica nanoparticles based room-temperature phosphorescence probe for detection of 2,4-dichlorophenol.

This paper reports a facile and general method for preparing an imprinted polymer thin shell with Mn-doped ZnS quantum dots (QDs) at the surface of silica nanoparticles by stepwise precipitation polymerization to form the highly-controllable core-shell nanoparticles (MIPs@SiO2-ZnS:Mn QDs) and sensitively recognize the target 2,4-dichlorophenol (2,4-DCP). Acrylamide (AM) and ethyl glycol dimethacrylate (EGDMA) were used as the functional monomer and the cross-linker, respectively. The MIPs@SiO2-ZnS:Mn QDs had a controllable shell thickness and a high density of effective recognition sites, and the thickness of uniform core-shell 2,4-DCP-imprinted nanoparticles was controlled by the total amounts of monomers. The MIPs@SiO2-ZnS:Mn QDs with a shell thickness of 45 nm exhibited the largest quenching efficiency to 2,4-DCP by using the spectrofluorometer. After the experimental conditions were optimized, a linear relationship was obtained covering the linear range of 1.0-84 µmol L(-1) with a correlation coefficient of 0.9981 and the detection limit (3σ/k) was 0.15 µmol L(-1). The feasibility of the developed method was successfully evaluated through the determination of 2,4-DCP in real samples. This study provides a general strategy to fabricate highly-controllable core-shell imprinted polymer-contained QDs with highly selective recognition ability.

Optical detection of λ-cyhalothrin by core-shell fluorescent molecularly imprinted polymers in Chinese spirits.

In this study, fluorescent molecularly imprinted polymers (FMIPs), which were for the selective recognition and fluorescence detection of λ-cyhalothrin (LC), were synthesized via fluorescein 5(6)-isothiocyanate (FITC) and 3-aminopropyltriethoxysilane (APTS)/SiO2 particles. The SiO2@FITC-APTS@MIPs were characterized by Fourier transform infrared (FT-IR), UV-vis spectrophotometer (UV-vis), fluorescence spectrophotometer, thermogravimetric analysis (TGA), confocal laser scanning microscope (CLSM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The as-synthesized SiO2@FITC-APTS@MIPs with an imprinted polymer film (thickness was about 100 nm) was demonstrated to be spherically shaped and had good monodispersity, high fluorescence intensity, and good selective recognition. Using fluorescence quenching as the detection tool, the largest fluorescence quenching efficiency (F0/F - 1) of SiO2@FITC-APTS@MIPs is close to 2.5 when the concentration of the LC is 1.0 µM L(-1). In addition, a linear relationship (F0/F - 1= 0.0162C + 0.0272) could be obtained covering a wide concentration range of 0-60 nM L(-1) with a correlation coefficient of 0.9968 described by the Stern-Volmer equation. Moreover, the limit of detection (LOD) of the SiO2@FITC-APTS@MIPs was 9.17 nM L(-1). The experiment results of practical detection revealed that the SiO2@FITC-APTS@MIPs as an attractive recognition element was satisfactory for the determination of LC in Chinese spirits. Therefore, this study demonstrated the potential of SiO2@FITC-APTS@MIPs for the recognition and detection of LC in food.