Schiff Base Reaction Research Articles

Molecule Engineering Metal-Organic Framework-Based Organic Photoelectrochemical Transistor Sensor for Ultrasensitive Bilirubin Detection.

The functionalization of metal-organic frameworks (MOFs) with organic small molecules by in situ postsynthetic modification has garnered considerable attention. However, the precise engineering of recognition sites using this method remains rarely explored in optically controlled bioelectronics. Herein, employing the Schiff base reaction to embed the small molecule (THBA) into a Zr-MOF, we fabricated a hydroxyl-rich MOF on the surface of titanium dioxide nanorod arrays (U6H@TiO2 NRs) to develop light-sensitive gate electrodes with tailored recognition capabilities. The U6H@TiO2 NR gate electrodes were integrated into organic photoelectrochemical transistor (OPECT) sensing systems to tailor a sensitive device for bilirubin (I-Bil) detection. In the presence of I-Bil, coordination effects, hydrogen bonding, and π-π interactions facilitated strong binding between U6H@TiO2 NRs and the target I-Bil. The electron-donating property of I-Bil influenced the gate voltage, enabling precise control of the channel status and modulation of the channel current. The OPECT device exhibited exceptional analytical performance toward I-Bil with wide linearity ranging from 1 × 10-16 to 1 × 10-9 M and a low limit detection of 0.022 fM. Leveraging the versatility of small molecules for boosting the functionalization of materials, this work demonstrates the great potential of the small molecule family for OPECT bioanalysis and holds promise for the advancement of OPECT sensors.

Urea for removing the aldehydes and ketones in leather VOCs and recycling performance of ethanol eluent

Hexanal, found in high-grade leather sofas, has a high odor activity value of 21285.8. Thus far, a method to remove hexanal from leather VOCs has not been reported. In this study, we developed a hexanal removal method that involves the elution of hexanal with an eluent of urea and ethanol (EtOH). We achieved the best hexanal removal rate with a urea concentration of 14 g/L, a liquid ratio of 75, a reaction time of 120 min, a temperature of 60 °C, an ultrasonic environment, and the presence of anhydrous CaCl2. The mechanism of hexanal removal by urea was confirmed via quartz crystal microbalance with dissipation monitoring, Fourier-transform infrared spectroscopy, and 1H NMR. Moreover, the EtOH eluent exhibited excellent recyclability over five cycles, where EtOH was distilled after every cycle and fresh eluent was prepared with the recycled EtOH. The physicochemical properties of the leather also remained unchanged after this treatment. Our strategy based on the Schiff base reaction between urea and carbonyl compounds can be extended to other aldehydes and ketones of leather VOCs to improve the air quality in leather environments.

Multifunctional bacterial cellulose-bentonite@polyethylenimine composite membranes for enhanced water treatment: Sustainable dyes and metal ions adsorption and antibacterial properties

Developing multifunctional materials for water treatment remains a significant challenge. Bacterial cellulose (BC) holds immense potential as an adsorbent with high pollutant-binding capacity, hydrophilicity, and biosafety. In this study, N-acetylglucosamine was used as a carbon source to ferment BC, incorporating amide bonds in situ. Bentonite, renowned for its adsorption properties, was added to the culture medium, resulting in BC-bentonite composite membranes via a one-step fermentation process. Polyethyleneimine (PEI) was crosslinked with amide bonds on the membrane via glutaraldehyde through Schiff base reactions to enhance the performance of the composite membrane. The obtained membrane exhibited increased hydrophilicity, enhanced active adsorption sites, and enlarged specific surface area. It not only physically adsorbed contaminants through its unique structure but also effectively captured dye molecules (Congo red, Methylene blue, Malachite green) via electrostatic interactions. Additionally, it formed stable complexes with metal ions (Cd²⁺, Pb²⁺, Cu²⁺) through coordination and effectively adsorbed their mixtures. Moreover, the composite membrane demonstrated the broad-spectrum antibacterial activity, effectively inhibiting the growth of tested bacteria. This study introduces an innovative method for fabricating composite membranes as adsorbents for complex water pollutants, showing significant potential for long-term wastewater treatment of organic dyes, heavy metal ions, and pathogens.

PH and temperature dual-responsive magnetic yolk-shell mesoporous silica nanoparticles for controlled drug delivery

New magnetic yolk-shell mesoporous silica nanoparticles (Fe3O4@V-mSiO2-PNVCL) were prepared by grafting temperature-sensitive amino-terminated poly (N-vinylcaprolactam) (PNVCL-NH2) on the surface of aldehyde-functionalized magnetic mesoporous silica nanoparticles (Fe3O4@V-mSiO2-CHO) through a Schiff base reaction. Various characterizations were used to confirm the structures, and the drug loading and release behaviors were studied. The drug loading was achieved as PNVCL stretched at room temperature and the drug loading content was up to 54.7% due to the large cavities. The encapsulation of drug from leakage in the blood environment was realized as PNVCL collapsed at physiological temperature. The fracture of pH-liable imine bonds in a slightly acidic tumor environment triggered the burst release of cargo. The Fe3O4@V-mSiO2-PNVCL showed super paramagnetic behavior (21.01 emu∙g−1) which could achieve magnetic targeting. The MTT assay confirmed that the nanoparticles exhibited low cytotoxicity. Furthermore, the cellular uptake experiments indicated that DOX-loaded nanoparticles were successfully internalized into cancer cells. Therefore, the composite nanoparticles are ideal choices for drug carriers.

NH2-MXene/OXG nanocomposite hydrogel with efficient photothermal antibacterial activity for potentially removing biofilms

The adhesion of bacteria to the surface leads to formation of biofilms causing numerous infection problems in implanting medical devices or interventional therapy. Traditional treatment for such problems is generally to administrate patients with antibiotics or antifungal agent. Alternatively, devices are taken out of the body to mechanically destroy the biofilm and re-used by surgery. In this study, a straightforward method was developed to remove biofilms using a MXene-based photothermal hydrogel. The hydrogel consists of dynamic crosslinking network formed by Schiff-base reaction between aldehyde-containing xyloglucan (OXG) and amine-containing MXene (NH2-MXene), which showed efficient killing of both gram-positive Staphylococcus aureus (S. aureus) and gram-negative Escherichia coli (E. coli) bacteria upon near-infrared (NIR) laser irradiation. The NH2-MXene/OXG nanocomposite hydrogel showed a high photothermal antibacterial efficiency and stable photothermal conversion, demonstrated by efficient removal of biofilms ex vivo.

Dynamic Cross-Linking, Self-Healing, Antibacterial Hydrogel for Regenerating Irregular Cranial Bone Defects.

Given the widespread clinical demand, addressing irregular cranial bone defects poses a significant challenge following surgical procedures and traumatic events. In situ-formed injectable hydrogels are attractive for irregular bone defects due to their ease of administration and the ability to incorporate ceramics, ions, and proteins into the hydrogel. In this study, a multifunctional hydrogel composed of oxidized sodium alginate (OSA)-grafted dopamine (DO), carboxymethyl chitosan (CMCS), calcium ions (Ca2+), nanohydroxyapatite (nHA), and magnesium oxide (MgO) (DOCMCHM) was prepared to address irregular cranial bone defects via dynamic Schiff base and chelation reactions. DOCMCHM hydrogel exhibits strong adhesion to wet tissues, self-healing properties, and antibacterial characteristics. Biological evaluations indicate that DOCMCHM hydrogel has good biocompatibility, in vivo degradability, and the ability to promote cell proliferation. Importantly, DOCMCHM hydrogel, containing MgO, promotes the expression of osteogenic protein markers COL-1, OCN, and RUNX2, and stimulates the formation of new blood vessels by upregulating CD31. This study could provide meaningful insights into ion therapy for the repair of cranial bone defects.

Insight on photocatalytic synchronous oxidation and reduction for pollutant removal: Chemical energy conversion between macromolecular organic pollutants and heavy metal

Collaborative treatment of pollutants is a promising approach for wastewater treatment. In this work, a covalent organic framework material (COFs) with an imine structure was synthesised by the Schiff base reaction, and photochemical tests showed good photochemical effects. It was used to explore the photocatalytic treatment of co-existing pollutants (heavy metal ions and antibiotics) and the performance of treating co-existing wastewater was investigated. The degradation performance of levofloxacin (LVX) and Cr(VI) was improved in the coexisting pollutants system, with the LVX degradation being 4.2 times more effective than that of the LVX solitary system. Moreover, this phenomenon was also observed in LVX/Ag(I), LVX/Fe(III), sulfadiazine/Cr(VI), norfloxacin/Cr(VI) and tetracycline/Cr(VI) systems. The analysis of active species suggesting that the synergistic promotion of photocatalytic oxidation-reduction systems was not only promoting from the improvement of simple charge separation, but it was also found that high-valent metal species can act directly in the oxidative decomposition of antibiotics. The interaction of pollutants and intermediates were rationally exploited and confirmed by control experiments and theoretical calculation. This conclusion helps us to re-examine the underlying mechanisms of photocatalytic synchronous oxidation and reduction reactions, simultaneously beneficial for the development of mixed pollutant control processes.

High internal phase Pickering emulsions stabilized by Zein-hyaluronic acid conjugate particles and their application in active substances protection

In recent years, active substances have been extensively applied in the fields of food, cosmetics, and pharmaceuticals. However, their preservation and transportation have posed challenges due to issues such as oxidation and photodegradation. This study proposes a method for synthesizing Zein-Hyaluronic Acid (Zein-HA) conjugate particles via the Schiff base reaction, utilizing these conjugate particles to encapsulate and protect active substances within a stable emulsion system. Compared to zein, the modified conjugate particles exhibit significantly improved dispersibility, amphiphilicity, interfacial affinity, and emulsifying properties. Consequently, these particles are capable of stabilizing high internal phase Pickering emulsions with an oil phase volume fraction of up to 80 (v/v)%, thereby enabling the carriage of a higher load of active components. Furthermore, the prepared emulsions demonstrate excellent storage stability, resistance to ionic strength (250–2000 mM NaCl), and outstanding antioxidative characteristics. Moreover, after 8 h of UV light exposure, the retention rates of the active substances (curcumin, astaxanthin, and resveratrol) exceed 60 %. Therefore, these emulsions hold substantial potential to be applied as a carrier system in the food, cosmetics, and pharmaceutical industries.

Multifunctional Glycopeptide-Based Hydrogel via Dual-Modulation for the Prevention and Repair of Radiation-Induced Skin Injury.

The radiation-induced skin injury (RISI) remains a great challenge for clinical wound management and care after radiotherapy, as patients will suffer from the acute radiation injury and long-term chronic inflammatory damage during the treatment. The excessive ROS in the early acute stage and prolonged inflammatory response in the late healing process always hinder therapeutic efficiency. Herein, we developed an extracellular matrix (ECM)-mimetic multifunctional glycopeptide hydrogel (oCP@As) to promote and accelerate RISI repair via a dual-modulation strategy in different healing stages. The oCP@As hydrogel not only can form an ECM-like nanofiber structure through the Schiff base reaction but also exhibits ROS scavenging and DNA double-strand break repair abilities, which can effectively reduce the acute radiation damage. Meanwhile, the introduction of oxidized chondroitin sulfate, which is the ECM polysaccharide-like component, enables regulation of the inflammatory response by adsorption of inflammatory factors, accelerating the repair of chronic inflammatory injury. The animal experiments demonstrated that oCP@As can significantly weaken RISI symptoms, promote epidermal tissue regeneration and angiogenesis, and reduce pro-inflammatory cytokine expression. Therefore, this multifunctional glycopeptide hydrogel dressing can effectively attenuate RISI symptoms and promote RISI healing, showing great potential for clinical applications in radiotherapy protection and repair.

Fabrication and characteristics of functional hydrogels based on dopamine‐grafted gelatin and oxyglucan with incorporation of dipotassium glycyrrhizinate potential for wound dressings

AbstractHydrogel have been widely used to promote skin tissue regeneration and accelerate wound healing. The development of injectable hydrogels with multi‐functional integration is a priority, especially with antibacterial properties and cytocompatibility. Here, we reported a simple, and versatile method to fabricate a functional hydrogel with potential for wound dressing applications. The dopamine‐grafted gelatin (GT‐DA) and oxidized dextran (oxyglucan, ODex) were synthesized, and dipotassium glycyrrhizinate (DG) was in situ incorporated to fabricate the composite hydrogels (GDO) through the Schiff base reaction. SEM images revealed that hydrogel has a porous structure. By increasing the ratio of GT‐DA to ODex from 1 to 4, the storage modulus (G') and hydrogel network stability nearly doubled, reaching 900 Pa and 220% strain, respectively. The enhancement in mechanical properties could be attributed to the higher cross‐linking density resulting from increased Schiff base bonds in the GDO hydrogels. Furthermore, the GDO hydrogel exhibited antioxidant activity and antibacterial effects on Escherichia coli and Staphylococcus aureus. Moreover, the hydrogel demonstrated cytocompatibility after culturing with human umbilical vein endothelial cells (HUVECs). The results proved that the fabricated GDO hydrogels have the potential to be used as wound dressings.

Development of embedded bioprinting for fabricating zonally stratified articular cartilage

Embedded bioprinting enables direct deposition of bioinks in three dimensions inside a support bath with shear-thinning and self-healing capabilities, and it has been used to fabricate complex tissues and organs for several biomedical applications. In this study, a support bath comprising gelatin/alginate microparticles and oxidized alginate solution was developed and crosslinked in situ with carbonyl hydrazide-modified gelatin bioink via the Schiff base reaction. The numerical model of embedded printing was established to analyze the extrusion process and disturbance of the support bath. The process window (e.g., extrusion pressure, nozzle moving speed, nozzle size, and support bath composition) was established experimentally to ensure stable fiber formation. In addition, the compressive modulus of the printed construct has been reinforced due to the formation of interpenetrating polymer networks in the microparticles. Based on the process investigation, a zonally stratified artificial cartilage with a three-layered structure was designed: vertically printed fibers in the bottom, oblique fibers in the middle, and horizontally printed fibers in the superficial layer. The bioprinted cartilage supported cell survival, proliferation, and spreading, with the observed deposition of cartilage-specific proteins, offering a new strategy for developing tissue-engineered cartilage constructs with biological and histological relevance.

Characterization of gelatin-oxidized riclin cryogels and their applications as reusable ice cubes in shrimp preservation

Traditional ice is usually employed to preserve food freshness and extend shelf life. However, ice cannot bear repeated freeze − thaw cycles during the transportation and retailing process, resulting in microbial cross-contamination and spoilage of foods. Herein, succinoglycan riclin was oxidated (RO) and crosslinked with gelatin (Ge), the Ge-RO cryogels were prepared via Schiff base reaction and three freeze − thaw cycles. The Ge-RO cryogels showed improved storage modulus (G′) and thermal stability compared with pure gelatin hydrogel. The polymer framework of Ge-RO gels exhibited stable properties against ice crystals destructions during nine freeze − thaw treatments. During the storage and repeated freeze − thaw treatments of shrimps, Ge-RO cryogels exhibited a remarkable preservation effect on shrimps, and their freshness was evaluated using an electronic nose technique equipped with ten sensors. The results demonstrated that the shrimp muscle preserved in ice generated off-odors and resulted in high sensor responses. The sensor responses were reduced sharply of shrimps preserved in cryogels. Moreover, 1H NMR-based metabolomics analysis revealed that shrimps in Ge-RO cryogels group reversed the metabolic perturbations compared with the traditional ice group, the metabolic pathways were related to energy metabolism, nucleotide metabolism, and amino acid metabolism, which provide new clues to the freshness of shrimps. Furthermore, RO exhibited superior antimicrobial activity against E. coli and S. aureus microorganisms. Thus, the crosslinked cryogels are potentially applicable to food preservation, offering sustainable and reusable solutions against traditional ice.

Unsymmetric Co-Facial "Salixpyrrole" Hydrogen Evolution Catalysts: Two Metals are Better than One.

Designing ligand architectures that can mimic enzyme active sites is a promising approach for developing efficient small molecule activation catalysts for sustainable energy applications. Some key design features include chemically distinct binding pockets for multiple metal centers and a three-dimensional structure that controls the positioning of catalytic sites. With these principles in mind, mono- and bimetallic unsymmetric cofacial palladium complexes, 2 and 3, respectively, bearing ligands with calixpyrrole and salen coordination sites, or "salixpyrrole" ligands, are reported. These species were accessed in a straightforward Schiff-base reaction with appreciable yields. In addition, both 2 and 3 were found to be active hydrogen evolution electrocatalysts using para-toluenesulfonic acid monohydrate as the proton source. The two salixpyrrole species displayed different mechanisms of action, with 2 showing a second-order dependence on acid concentration, whereas 3 exhibited a first-order dependence. Moreover, the bimetallic catalyst was significantly more efficient, with higher turnover frequencies, 4640 s-1 vs 1680 s-1 for 2, and lower overpotentials, 0.39 V vs 0.69 V for 2. The results reported herein provide proof-of-concept that bimetallic catalysts with chemically distinct binding sites demonstrate enhanced catalytic properties in comparison to monometallic or symmetric analogues.

Tough, self-healing, adhesive double network conductive hydrogel based on gelatin-polyacrylamide covalently bridged by oxidized sodium alginate for durable wearable sensors

Pursuing high-performance conductive hydrogels is still hot topic in development of advanced flexible wearable devices. Herein, a tough, self-healing, adhesive double network (DN) conductive hydrogel (named as OSA-(Gelatin/PAM)-Ca, O-(G/P)-Ca) was prepared by bridging gelatin and polyacrylamide network with functionalized polysaccharide (oxidized sodium alginate, OSA) through Schiff base reaction. Thanks to the presence of multiple interactions (Schiff base bond, hydrogen bond, and metal coordination) within the network, the prepared hydrogel showed outstanding mechanical properties (tensile strain of 2800 % and stress of 630 kPa), high conductivity (0.72 S/m), repeatable adhesion performance and excellent self-healing ability (83.6 %/79.0 % of the original tensile strain/stress after self-healing). Moreover, the hydrogel-based sensor exhibited high strain sensitivity (GF = 3.66) and fast response time (<0.5 s), which can be used to monitor a wide range of human physiological signals. Based on this, excellent compression sensitivity (GF = 0.41 kPa−1 in the range of 90–120 kPa), a three-dimensional (3D) array of flexible sensor was designed to monitor the intensity of pressure and spatial force distribution. In addition, a gel-based wearable sensor was accurately classified and recognized ten types of gestures, achieving an accuracy rate of >96.33 % both before and after self-healing under three machine learning models (the decision tree, SVM, and KNN). This paper provides a simple method to prepare tough and self-healing conductive hydrogel as flexible multifunctional sensor devices for versatile applications in fields such as healthcare monitoring, human-computer interaction, and artificial intelligence.

Synthesis, Characterization, Docking Study and Biological Activates of New 3-Aminorhodanine Derivatives

Abstract: Increase in fatalities among cancer patients is one of untreated facts and today cancer remains one of the main health issues. The most common cause of cancer death is lung cancer. Rhodanine has been recognized as a privileged scaffold in medicinal chemistry due to its well-known ability to demonstrate a broad range of biological activities, and most of its derivatives exhibited remarkable anticancer activity in the (μg/mL) concentration range, while causing negligible cytotoxicity to normal cells. New N- and 5- disubstituted aminorhodanine derivatives were synthesized by Schiff base and Knoevenagel condensation reactions over two consecutive steps. Human cancer cells and Hdfn (human dermal fibroblasts isolated from neonatal foreskin) cells line, were used to evaluate the synthesized compounds’ activity by MTT assay. The new compounds revealed higher anticancer activity against A549 lung cells cancer when compared with reference drug Erlotinib (anticancer drug) and determined no toxicity or safety on normal cell. Among the tested compounds, 2b2 compound show potent anticancer activity which have IC50 about (55.8 μg/mL).

Insights from DFT and mechanistic analysis of surface-precision carbon self-doped porous g-C3N4 for enhanced visible light-driven hydrogen evolution

Substituting carbon for nitrogen in g-C3N4 enhances π-electrons activity and photocatalytic performance, despite the challenges posed by the higher electronegativity of nitrogen. We successfully achieved the substitution of C atoms for N atoms via the copolymerization of melamine and cytosine utilizing the Schiff base reaction, altering the g-C3N4 band structure from 2.74 to 2.49 eV and enhancing photoinduced electron reduction due to the introduction of −N-C = C- unit into the g-C3N4 network. The C-incorporated g-C3N4 extended the light-response range to 673 nm and improved the electron cloud density around the self-doping sites, significantly reducing the ΔGH* as indicated the DFT results, implying the efficient separation and migration of photoinduced carriers in g-C3N4. As anticipated, the photocatalytic hydrogen evolution (PHE) rate of the optimized C self-doped g-C3N4 was five and seven times higher than that of the pristine g-C3N4 under the full spectrum and the visible light (λ ≥ 400 nm), respectively. Moreover, g-C3N4-n also display superior activity (6.73, 4.48, 3.42, and 0.76 %) under the different wavelengths (λ = 420, 450, 480 nm, and 540 nm respectively). This report reveals a subtle atom-tailoring scheme to control carbon self-doping sites within the g-C3N4 framework, modulating its inherent electronic properties and photoactivity.

Dynamically reversible cross-linked polymer electrolytes with highly ionic conductivity for dendrite-free lithium metal batteries

High-safety PEO-based electrolytes have attracted widespread attention, but their inefficient conduction of Li ions and poor contact with electrode interfaces deteriorate the performances of rechargeable lithium metal batteries. Herein, we design a vitrimer polymer electrolyte (V-SPE-PEG) with abundant dynamic imine bonds via Schiff base reaction between aldehyde and ammonia, which achieves high ionic conductivity and good interfacial compatibility with lithium anode. The dynamic polymer network in V-SPE-PEG exhibits solid-state plasticity because reversible imine bonding reactions enable the integrity of the polymer network to be maintained while altering the cross-linked points under external stimuli. Therefore, this 3D dynamic cross-linked network effectively facilitates the polymer chain dynamics and meanwhile enhances ionic conductivity. Additionally, dynamic bond exchange fosters electrolyte flowability and self-healing during lithium deposition, promoting a tightly integrated electrode/electrolyte interface while inhibiting lithium dendrites growth. Consequently, lithium symmetric cells utilizing the V-SPE-PEG electrolyte demonstrate exceptional long-term cycling stability, surpassing 1100 h and exhibit outstanding ionic conductivity of 2.7 × 10−4 S cm−1 at 30 °C. The LiFePO4||Li battery maintains stable cycling performance at both 40 °C and 60 °C. This study introduces an innovative approach to designing solid-state electrolytes for lithium-metal batteries.

Quaternized oxidized sodium alginate injectable hydrogel with high antimicrobial and hemostatic efficacy promotes diabetic wound healing

In this paper, a hydrogel material with efficient antibacterial, hemostatic, self-healing, and injectable properties was designed for the treatment of diabetic wounds. Firstly, quaternary ammonium salts were grafted with oxidized sodium alginate, and quaternized oxidized sodium alginate (QOSA) was synthesized. Due to the introduction of quaternary ammonium group it has antibacterial and hemostatic effects, at the same time, due to the presence of aldehyde group it can be reacted with carboxymethyl chitosan (CMCS) to form a hydrogel through the Schiff base reaction. Furthermore, deer antler blood polypeptide (DABP) was loaded into the hydrogel (QOSA&CMCS&DABP), showing good swelling ratio and bacteriostatic effect. In vitro and in vivo experiments demonstrated that the hydrogel not only quickly inhibited hepatic hemorrhage in mice and reduced coagulation index and clotting time in vitro, but also significantly enhanced collagen deposition at the wound site, accelerating wound healing. This demonstrates that the multifunctional hydrogel materials (QOSA&CMCS&DABP) have promising applications in the acceleration of skin wound healing and antibacterial promotion.

Stimuli-responsive antioxidant Pickering emulsions stabilized by functionalized cellulose nanocrystals

Stimuli-responsive antioxidant Pickering emulsions play crucial role in many industrial areas. This study demonstrated for the first time oil-in-water Pickering emulsions with outstanding antioxidation and responsive demulsification stabilized by functionalized cellulose nanocrystals (CNCs). Dialdehyde cellulose nanocrystals (DACs) were first prepared through the oxidation of CNCs with periodate, followed by the grafting of p-aminophenols (PAPs) onto their surfaces through Schiff base reaction, affording PAP grafted DACs (DAC-g-PAP) via dynamic covalent linkage. The degree of the oxidation (DO) of DACs had a significant effect on the yield of the targeting DAC-g-PAP nanoparticles. High DO (≥40 %) potentially led to the degradation of DACs during the grafting of PAP. The introduced PAP endowed DACs with excellent radical scavenging capability, thereby providing antioxidant properties while improving the hydrophobicity. DAC-g-PAP nanoparticles were then applied as Pickering emulsifiers to prepare oil-in-water Pickering emulsions. The resultant Pickering emulsions indicated exceptional antioxidant and pH-responsiveness together with good freezing-thaw stability. The structures of DAC-g-PAP nanoparticles were thoroughly characterized in this study.

Covalent organic framework-functionalized magnetic MXene nanocomposite for efficient pre-concentration and detection of organophosphorus and organochlorine pesticides in tea samples before gas chromatography–triple quadrupole mass spectrometry analysis

In this study, a hydrophobic covalent organic framework-functionalized magnetic composite (CoFe2O4@Ti3C2@TAPB−TFTA) with a high specific area with 1,3,5-tris(4-aminophenyl)benzene (TAPB) and 2,3,5,6-tetrafluoroterephthalaldehyde (TFTA) was designed and synthesized through Schiff base reaction. An efficient magnetic solid-phase extraction method was established and combined with gas chromatography–triple quadrupole mass spectrometry to sensitively determine 10 organochlorine and organophosphorus pesticides in tea samples. The established method exhibited good linearity in the range of 0.05–120 μg/L and had low limits of detection (0.013–0.018 μg/L). The method was evaluated with tea samples, and the spiked recoveries of pesticides in different tea samples reached satisfactory values of 85.7–96.8%. Moreover, the adsorption of pesticides was spontaneous and followed Redlich–Peterson isotherm and pseudo-second-order kinetic models. These results demonstrate the sensitivity, effectiveness, and reliability of the proposed method for monitoring organochlorine and organophosphorus pesticides in tea samples, providing a preliminary basis for researchers to reasonably design adsorbents for the efficient extraction of pesticides.