Molecularly imprinted polymer functionalized silica nanoparticles for enantioseparation of racemic tryptophan in aqueous solution

Enantioselective Molecularly Imprinted Polymer for Tyrosine, Tryptophan, and Phenylalanine, and the Possibility of the Crop-Circle-Like Imprinting

Molecularly imprinted polymer (L-MIP) for L-tyrosine (L-Tyr) is prepared by the complexation between quaternized poly(4-vinylpyridine/divinylbenzene) (QVP) and poly(acrylamide-co-acrylic acid) (PAmA) in alkaline solution. The L-MIP shows higher enantioselectivity for L-isomers of tyrosine, together with tryptophan (Trp) and phenylalanine (Phe) compared to the D-isomers of them. The sorption isotherms of the three D-enantiomers are converged to one isotherm. It can reflect that the sorption of D-enantiomers can be relied mainly on the common segment, -CH2 -CH(NH2 )-COOH, neglecting any effect of bulkier aromatic groups. The imprinted common segment can be opened on the surface of MIP from the D-enantiomers. For the L-enantiomers, the sorption discrepancies are depended on the size of the aromatic group implying that the phenolic moiety of L-Tyr can be also opened. Thus, the imprinted sites are proposed to be opened on the surface of L-MIP similar to the crop-circle-like. The enantioselectivity factors, αef  = QL /QD , for Tyr, Trp, and Phe are 1.52, 1.30, and 1.52 for L- to D-isomers, respectively. And the uptake differences between D- and L-enantiomers of Tyr, Trp, and Phe are 31.8, 20.7, and 29 mg per 1 g MIP, respectively.

Facile synthesis of flower-like sandwich-structured molecularly imprinted polymers for efficient recognition of target protein from egg white

In this work, a facile method for synthesis of flower-like sandwich-structured molecularly imprinted polymers (NiO@PDA/MIPs) was proposed for protein recognition. Polydopamine modified flower-like NiO was used as substrate to immobilize the target protein (ovalbumin, OVA), and dopamine was utilized as functional monomer to form the imprinted layer. The whole preparation process was conducted in aqueous solution at room temperature. The key preparation conditions were studied systematically. Owing to the large surface-to-volume of the flower-like structure and the multifunctional groups on the polydopamine layer, the NiO@PDA/MIPs showed large binding capacity (143.2 mg/g), efficient adsorption kinetics (60 min) and excellent selectivity toward OVA. Meanwhile, the NiO@PDA/MIPs possessed satisfactory stability and reusability. Finally, successful capture of OVA from egg white suggested its potential value in practical applications.

Emerging Applications of Silica Nanoparticles as Multifunctional Modifiers for High Performance Polyester Composites

Nano-modification of polyester has become a research hotspot due to the growing demand for high-performance polyester. As a functional carrier, silica nanoparticles show large potential in improving crystalline properties, enhancing strength of polyester, and fabricating fluorescent polyester. Herein, we briefly traced the latest literature on synthesis of silica modifiers and the resultant polyester nanocomposites and presented a review. Firstly, we investigated synthesis approaches of silica nanoparticles for modifying polyester including sol-gel and reverse microemulsion technology, and their surface modification methods such as grafting silane coupling agent or polymer. Then, we summarized processing technics of silica-polyester nanocomposites, like physical blending, sol-gel processes, and in situ polymerization. Finally, we explored the application of silica nanoparticles in improving crystalline, mechanical, and fluorescent properties of composite materials. We hope the work provides a guideline for the readers working in the fields of silica nanoparticles as well as modifying polyester.

Molecularly Imprinted Polymers for Dispersive (Micro)Solid Phase Extraction: A Review

The review describes the development of batch solid phase extraction procedures based on dispersive (micro)solid phase extraction with molecularly imprinted polymers (MIPs) and magnetic MIPs (MMIPs). Advantages and disadvantages of the various MIPs for dispersive solid phase extraction and dispersive (micro)solid phase extraction are discussed. In addition, an effort has also been made to condense the information regarding MMIPs since there are a great variety of supports (magnetite and magnetite composites with carbon nanotubes, graphene oxide, or organic metal framework) and magnetite surface functionalization mechanisms for enhancing MIP synthesis, including reversible addition-fragmentation chain-transfer (RAFT) polymerization. Finally, drawbacks and future prospects for improving molecularly imprinted (micro)solid phase extraction (MIMSPE) are also appraised.