Selective Enrichment of Clenbuterol onto Molecularly Imprinted Polymer Microspheres with Tailor-made Structure and Oxygen Functionalities

Adsorption and Recognition Property of Tyrosine Molecularly Imprinted Polymer Prepared via Electron Beam Irradiation

To realize the selective separation of L-tyrosine (L-Tyr) and avoid the drawbacks of traditional thermal polymerization, electron beam irradiation polymerization was developed for the fabrication of L-Tyr molecularly imprinted polymers (MIPs). Firstly, L-Tyr MIPs were prepared with methacrylic acid and ethylene glycol dimethacrylate and without an initiator. Then, the influence of absorbed dosage and temperature on the adsorption capacity of L-Tyr, as well as the thermodynamic behavior, were investigated. The maximum adsorption capacity of 10.96 mg/g for MIPs was obtained with an irradiation dosage of 340 kGy under 15 °C, and the ΔH0 and ΔS0 of the adsorption process are -99.79 kJ/mol and -0.31 kJ/mol·K, respectively. In addition, the effect of adsorption time on adsorption performance was evaluated under different initial concentrations, and the kinetic behavior was fitted with four different models. Finally, the recognition property of the obtained MIPs was investigated with L-Tyr and two analogues. The obtained MIPs have an imprinting factor of 5.1 and relatively high selective coefficients of 3.9 and 3.5 against L-tryptophan and L-phenylalanine, respectively. This work not only provided an L-Tyr MIP with high adsorption capacity and selectivity but also provided an effective and clean method for the synthesis of MIPs.

Production of a matrix certified reference material for measurement and risk monitoring of clenbuterol in mutton

A novel matrix certified reference material (CRM) for clenbuterol in mutton (GBW 10216) was developed to assist measurement and risk monitoring of clenbuterol in mutton. The candidate CRM raw samples were obtained by oral administration of clenbuterol and investigating the pharmacokinetics of clenbuterol in sheep. A high-precision isotope dilution coupled with liquid chromatography tandem mass spectrometry (LC-ID-MS/MS) method was established and assigned the value of clenbuterol in mutton powder through combined detection of nine inter-laboratories. The certified value with expanded uncertainty was 21.1 ± 2.2 μg/kg (k = 2, 95% confidence) for clenbuterol in mutton. The prepared matrix CRM was sufficiently homogeneous between and within bottles. The long-term stability of clenbuterol in mutton powder was evaluated for 12 months at -20℃ and short-term stability for 7 days at 4℃ and 50℃. The uncertainties originating from characterization, homogeneity, and stability were systematically analyzed and evaluated. The prepared matrix CRM can be applied for proficiency testing and nationwide risk monitoring programs to guarantee the accuracy and comparability of clenbuterol measurement results in mutton.

Anion Exchange Affinity-Based Controllable Surface Imprinting Synthesis of Ultrathin Imprinted Films for Protein Recognition

Anion exchange affinity-based controllable surface imprinting is an effective approach to overcome low imprinting efficiency and high non-specific binding capacity. The template proteins were first immobilized on the anchored tetraalkylammonium groups of the nanoparticles via anion exchange affinity-based interactions, enabling monolayer sorption using a low template concentration. The combined use of surface-initiated photoiniferter-mediated polymerization to precisely control the imprinted film thickness, allowing the formation of homogeneous binding cavities, and the construction of effective binding sites resulted in a low non-specific binding capacity and high imprinting efficiency. The obtained imprinted films benefited from the anion exchange mechanism, exhibiting a higher imprinting factor and faster binding rate than the reference material. Binding tests revealed that the binding strength and selective recognition properties could be tuned to a certain extent by adjusting the NaCl concentration. Additionally, in contrast to the harsh template elution conditions of the covalent immobilization approach, over 80% of the template molecules were readily removed from the imprinted films using supersonic elution with an aqueous mixture of NaCl and HAc. Introducing template immobilization by anion exchange interactions to the synthesis of imprinted materials may provide a new approach for effective biomacromolecular imprinting.

A Mild Method for Preparation of Highly Selective Magnetic Biochar Microspheres

We report the use of biochar and Fe₃O₄ nanoparticles as co-stabilizers for oil-in-water (o/w) Pickering emulsion. The emulsion is subsequently used to prepare magnetic tetracycline-imprinted biochar composite microspheres (MMIPMs) with good uniformity and high selectivity. The MMIPMs were characterized by scanning electron microscopy (SEM), Brunner-Emmet-Teller (BET) measurements, Fourier transform infrared spectrometry (FT-IR), X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and thermogravimetry analysis (TGA). The adsorption properties of tetracycline to the MMIPMs were investigated using different adsorption experiments including adsorption kinetic experiment, equilibrium binding experiment, selectivity evaluation and competitive adsorption tests. The theoretical maximum adsorption capacity of the MMIPMs (15.45 mg g⁻¹) was greater than that of the raw biochar (2.10 mg g⁻¹) and non-imprinted biochar composite microspheres (3.39 mg g⁻¹) for tetracycline. Further, the MMIPMs were used as adsorbent for magnetic solid phase extraction (SPE) for the extraction of tetracycline present in drinking water, milk, fish and chicken samples. Under optimal conditions, the results showed good recovery yield ranging from 88.41% to 106.29% with a relative standard deviation (RSD) ranging from 0.35% to 6.83%, respectively.

Biodegradable Polylactide/TiO2 Composite Fiber Scaffolds with Superhydrophobic and Superadhesive Porous Surfaces for Water Immobilization, Antibacterial Performance, and Deodorization

In this short communication, TiO₂-nanoparticle-functionalized biodegradable polylactide (PLA) nonwoven scaffolds with a superhydrophobic and superadhesive surface are reported regarding their water immobilization, antibacterial performance, and deodorization. With numerous regular oriented pores on their surface, the as-fabricated electrospun porous PLA/TiO₂ composite fibers possessed diameters in the range from 5 µm down to 400 nm, and the lengths were even found to be up to the meters range. The PLA/TiO₂ composite fiber surface was demonstrated to be both superhydrophobic and superadhesive. The size of the pores on the fiber surface was observed to have a length of 200 ± 100 nm and a width of 150 ± 50 nm using field-emission scanning electron microscopy and transmission electron microscopy. The powerful adhesive force of the PLA/TiO₂ composite fibers toward water droplets was likely a result of van der Waals forces and accumulated negative pressure forces. Such a fascinating porous surface (functionalized with TiO₂ nanoparticles) of the PLA/TiO₂ composite fiber scaffold endowed it with multiple useful functions, including water immobilization, antibacterial performance, and deodorization.