Over the past three decades, enzymatic polymerization has dramatically developed and gradually broadened as a creative methodology in the construction of polymeric materials with tailor-made structures and properties. Compared with transition metal catalyst polymerizations, enzymatic polymerization is more attractive in the biomedicine field due to the metal-free residue, good biocompatibility, and few by-products. Meanwhile, enzymatic polymerization has far more activity towards macrolides. In this review, the synthesis of lipase-catalyzed polymer materials is systematically summarized, focusing on the synthesis of the complex and well-defined polymers. The enzymatic polyester synthesis was then discussed concerning the different reaction types, including ring-opening polymerization, polycondensation, a combination of ring-opening polymerization with polycondensation, and chemoenzymatic polymerization. Besides, exploration of novel biocatalysts and reaction media was also described, with particular emphasis on the enzymes obtained via immobilization or protein engineering strategies, green solvents, and reactors. Finally, recent developments in catalytic kinetics and mechanistic studies through the use of spectroscopy, mathematics, and computer techniques have been introduced. Besides, we addressed the remaining central issues in enzymatic polymerization and discussed current studies aimed at providing answers.
1 August 2016 in Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
A rapid and effective sample pretreatment method, dispersant-assisted dynamic microwave extraction, was first applied to the extraction of six triazine herbicides from rice. The dynamic microwave extraction was coupled with matrix solid-phase dispersion (MSPD). The dispersant in MSPD was used to disperse the sample and adsorb impurities. Microwave irradiation was used to promote the transfer of the analyte and accelerate the extraction. The extraction and clean-up were performed simultaneously. The effects of experimental parameters, including the solvent type, volume of the extraction solvent, microwave power, type of dispersant, mass ratio of dispersant to rice, and flow rate of the extraction solvent, on the recoveries of the analytes were investigated. The limits of detection for the analytes ranged from 0.62 to 1.79 μg kg−1. The recoveries of the triazine herbicides in spiked rice samples were in the range of 84.3–101%, and the relative standard deviations were lower than 6.2%.