To protect consumers from risks related to overexposure to sulfadiazine, total residues of this antibacterial agent in animal-origin foodstuffs not exceed international regulations. To this end, a new electrochemical sensor based on a molecularly imprinted polymer nanocomposite using overoxidized polypyrrole and copper nanoparticles for the detection of sulfadiazine is elaborated. After optimization of the preparation of the electrochemical sensors, their differential pulse voltammetric signal exhibits an excellent stability and reproducibility at 1.05 V, with a large linear range between 10⁻⁹ and 10⁻⁵ mol L⁻¹ and a low detection limit of 3.1 × 10⁻¹⁰ mol L⁻¹. The produced sulfadiazine sensor was successfully tested in real milk samples. The combination of the properties of the electrical conduction of copper nanoparticles with the properties of the preconcentration of the molecularly imprinted overoxidized polypyrrole allows for the highly sensitive detection of sulfadiazine, even in real milk samples. This strategy is new and leads to the lowest detection limit yet achieved, compared to those of the previously published sulfadiazine electrochemical sensors.

This study involved the fabrication of a set of aluminum ion-grafted SBA-15 utilizing ethylenediamine and trimethylamine ionic liquids. The primary objective was to examine the impact of the fabrication environment on the physicochemical characteristics of the catalysts. Comprehensive characterization of the Al-SBA-15 catalysts was conducted using various techniques, including XRD, FTIR, surface area, pyridine FTIR, ²⁷Al-NMR, TGA, HRTEM, and FESEM, to analyze their physicochemical characteristics. Furthermore, the acidic characteristics were examined by conducting potentiometric titration in a nonaqueous solvent and employing FTIR spectroscopy to analyze the chemisorbed pyridine. The effectiveness of the fabricated acid materials was evaluated by testing their performance in acetic acid esterification with butanol. The findings obtained reveal that mesostructured SBA-15 remains intact following the successful inclusion of Al³⁺ ions into the silica frameworks. Additionally, a remarkable enhancement in the existence of both Bronsted and Lewis acid centers was noted due to the grafting process of Al³⁺ ions. At temperatures of 80 °C and 100 °C, the reaction in Al-SBA-15(T-120) proceeds swiftly, reaching approximately 32% and 38% conversion, respectively, within a span of 110 min. The excellent catalytic performance observed in the esterification reaction can be attributed to two factors: the homogeneous distribution of Al³⁺ ions within the SBA-15 frameworks and the acidic character of Al-SBA-15. The findings further indicate that the grafting process for incorporating Al³⁺ ions into the silica matrix is more efficient.

To monitor the release of fluorinated drugs from polymeric carriers, a novel ¹⁹F MRI enzyme-responsive contrast agent was developed and tested. This contrast agent was prepared by conjugation of 5-fluorouracil (5-FU) to hyperbranched poly(N,N-dimethylacrylamide) (HB-PDMA) via an enzyme-degradable peptide linker. Due to the different molecular sizes, the release of 5-FU from the 5-FU polymer conjugate resulted in a sufficiently substantial difference in spin-spin T₂ ¹⁹F NMR/MRI relaxation time that enabled differentiating between attached and released drug states. The 5-FU polymer conjugate exhibited a broad signal and short T₂ relaxation time under ¹⁹F NMR analysis. Incubation with the enzyme induced the release of 5-FU, accompanied by an extension of T₂ relaxation times and an enhancement in the ¹⁹F MRI signal. This approach is promising for application in the convenient monitoring of 5-FU drug release and can be used to monitor the release of other fluorinated drugs.

This study discloses the development of NiCr LDH, Ag@NiCr LDH, and Pd@NiCr LDH bifunction catalysts using a hydrothermal coprecipitation method followed by sol immobilization of metallic nanoparticles. The structures and morphologies of the synthesized nanocomposites were analyzed using FTIR, XRD, XPS, BET, FESEM-EDX, and HRTEM. The catalytic effectiveness of the samples was evaluated by tracking the progression of NaBH₄-mediated nitrobenzene (NB) reduction to aniline and CO oxidation using UV-visible spectrophotometry and an infrared gas analyzer, respectively. Pd@NiCr LDH displayed much higher performance for both reactions than the bare NiCr LDH. The catalyst Pd@NiCr LDH showed robust catalytic activity in both the oxidation of carbon monoxide (T_50% (136.1 °C) and T_100% (200.2 °C)) and NaBH₄-mediated nitrobenzene reduction (98.7% conversion and 0.365 min⁻¹ rate constant). The results disclose that the Ni²⁺@ Cr³⁺/Cr⁶⁺ @Pd° ion pairs inside the LDH act as a charge transfer center and hence significantly enhance the catalytic performance. As a result, this research offers the novel NiCr LDH catalyst as a bifunctional catalyst for air depollution control and the organic transformation process.

Ochratoxin A (OTA) is considered the most toxic member of the ochratoxin group. Herein, a novel label-free electrochemical sensor based on the horseradish peroxidase (HRP) enzyme is developed for OTA detection. The HRP enzyme was covalently immobilized on the working electrode of a planar boron-doped diamond (BDD) electrochemical microcell previously covered with diazonium film and grafted with single-walled carbon nanotubes (SWCNTs). Each surface modification step was evaluated by cyclic voltammetry and scanning electron microscopy. Square wave voltammetry was used for the detection of OTA. The linear working range of the biosensors ranged between 10⁻¹⁴ and 0.1 M, with a limit of detection (LOD) of 10 fM, an RSD equal to 5%, and a sensitivity of 0.8 µA per decade. In addition, the sensor showed good selectivity in the presence of OTA analogs; it was validated in samples such as corn, feed, and wheat. The metrological performance of the present sensor makes it a good alternative for OTA detection.

Stimuli-responsive polymeric vesicles are promising nanocarriers for the controlled release of chemotherapeutic agents. Although pH-responsive poly(2-(diisopropylamino)ethyl methacrylate) (PDPA) vesicles have been widely studied for the delivery of drugs such as doxorubicin hydrochloride, their use in 5-fluorouracil (5-FU) delivery has not been reported. Here, we demonstrate for the first time the application of PDPA-based vesicles for pH-triggered release of 5-FU. The vesicles were prepared via polymerization-induced self-assembly (PISA) using reversible addition–fragmentation chain transfer (RAFT) polymerization of DPA with poly(N,N-dimethylacrylamide) (PDMA) as a macro-chain transfer agent in a water/ethanol medium. The vesicles remained stable at physiological pH but disassembled under acidic conditions due to the hydrophobic-to-hydrophilic transition of the PDPA block, resulting in accelerated release of 5-FU. Cytotoxicity assays in HCT116 cells showed comparable anticancer efficacy between vesicle-loaded and free 5-FU, while blank vesicles were nontoxic. Confocal laser scanning microscopy (CLSM) confirmed efficient cellular uptake. These results highlight PDPA-based vesicles as a novel and effective nanoplatform for pH-responsive delivery of 5-FU.