A novel fluorescent molecularly imprinted polymer SiO2 @CdTe QDs@MIP for paraquat detection and adsorption.

Paraquat (PQ) residue is harmful for human health, agriculture, and the aquatic environment. This paper proposes a novel fluorescent molecularly imprinted polymer (MIP), SiO2 @CdTe QDs@MIP, for PQ detection and adsorption. The MIP was synthesized using 3-aminopropyltriethoxysilane as the functional monomer, 4,4'-bipyridyl as the template molecule, and tetraethoxysilane as the cross-linker. In addition, CdTe quantum dots featuring unique optical characteristics and excellent photochemical stability were combined as signal reporter. The synthesized MIP had a Brunauer-Emmett-Teller surface area of 68.2 m2 /g, pore volume of 0.42 cm3 /g and pore size of 6.9 nm, demonstrating the potential for both PQ detection and adsorption. For PQ detection, the MIP could achieve three orders of magnitude better than the limit of detection, and one order of magnitude wider detection range than existing methods. The PQ recovery values for real samples of water and corn were 96.4-102.1% and 93.9-97.3%, respectively. The amount of PQ detected by the MIP was within 98.05% on average of that using high-performance liquid chromatography. For PQ adsorption, the MIP had an adsorption capacity of 3.36 mg/g, and followed a pseudo-second-order kinetic model with excellent toxicological characteristics. Overall, the novel SiO2 @CdTe QDs@MIP proposed in this paper could facilitate an efficient and convenient method for PQ detection and adsorption.

Electrochemical sensor for determination of tulathromycin built with molecularly imprinted polymer film.

A novel tulathromycin (TLTMC) electrochemical sensor based on molecularly imprinted polymer (MIP) membranes was constructed. p-Aminothiophenol (p-ATP) and TLTMC were assembled on the surface of gold nanoparticles (AuNPs) modified on the gold electrode (GE) by the formation of Au-S bonds and hydrogen-bonding interactions. Besides, polymer membranes were formed by electropolymerization in a polymer solution containing p-ATP, tetrachloroaurate(III) acid (HAuCl4), tetrabutylammonium perchlorate (TBAP), and a template molecule TLTMC. A novel molecular imprinted sensor (MIS) in this experiment was achieved after the removal of TLTMC. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) measurements were used to illustrate the process of electropolymerization and its optimal conditions. The electrode with MIP obtained the linear of response range, which was between 3.0 × 10(-12) mol L(-1) and 7.0 × 10(-9) mol L(-1), and the limit of detection was 1.0 × 10(-12) mol L(-1). All the obtained results indicate that the MIS tends to be an effective electrochemical technique for the determination of TLTMC in real-time and in a complicated matrix.

Visible light-responsive polylactic acid@pullulan-chitosan/homojunction g-C3N4 bilayer antimicrobial films for fruit preservation.

The development of novel packaging materials with antimicrobial properties is crucial in preventing the microbial-induced spoilage of fruits, vegetables, and foodborne illnesses. In this study, homojunction g-C3N4 (HCN) photocatalysts with excellent photocatalytic performance were incorporated into a matrix consisting of pullulan/chitosan (Pul/CS). These photocatalysts were then electrostatically spun onto polylactic acid (PLA) films to fabricate PLA@Pul/CS/HCN nanofibrous composite films. The design of the bilayer films aimed to combine the physical properties of PLA film with the excellent antibacterial properties of nanofiber films, thereby achieving synergistic advantages. The incorporation of the HCN photocatalysts resulted in enhanced hydrophobicity, barrier function, and mechanical properties of the composite films. Under visible light irradiation, the PLA@Pul/CS/HCN films exhibited approximately 3.43 log and 3.11 log reductions of Escherichia coli and methicillin-resistant Staphylococcus aureus (MRSA), respectively, within 2 h. The excellent antimicrobial performance could be attributed to the synergistic effect of CS and the release of reactive oxygen species (ROS) from HCN. Moreover, the strawberries packaged in the PLA@Pul/CS/HCN film demonstrated diminished quality degradation and a prolonged shelf life following visible light irradiation treatment. This study will provide new insights into the exploration of safe and efficient antimicrobial food packaging.

Development and application of 3-chloro-1,2-propandiol electrochemical sensor based on a polyaminothiophenol modified molecularly imprinted film.

In this work, a novel electrochemical sensor for 3-chloro-1,2-propandiol (3-MCPD) detection based on a gold nanoparticle-modified glassy carbon electrode (AuNP/GCE) coated with a molecular imprinted polymer (MIP) film was constructed. p-Aminothiophenol (p-ATP) and 3-MCPD were self-assembled on a AuNP/GCE surface, and then a MIP film was formed by electropolymerization. The 3-MCPD template combined with p-ATP during self-assembly and electropolymerization, and the cavities matching 3-MCPD remained after the removal of the template. The MIP sensor was characterized by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and scanning electron microscopy (SEM). Many factors that affected the performance of the MIP membrane were discussed and optimized. Under optimal conditions, the DPV current was linear with the log of the 3-MCPD concentration in the range from 1.0 × 10(-17) to 1.0 × 10(-13) mol L(-1) (R(2) = 0.9939), and the detection limit was 3.8 × 10(-18) mol L(-1) (S/N = 3). The average recovery rate of 3-MCPD from spiked soy sauce samples ranged from 95.0% to 106.4% (RSD < 3.49%). Practically, the sensor showed high sensitivity, good selectivity, excellent reproducibility, and stability during the quantitative determination of 3-MCPD.