Thermo-responsive molecularly imprinted monolith in extraction

By -
Molecularly imprinted polymers (MIPs) are widely employed sorbents due to their improved selectivity. They are synthesized in the presence of the analyte, which is called template, and therefore the polymeric network is constructed around the target leaving selective chemical cavities when it is washed away. After the bulk synthesis, the polymer is crashed and sieved to obtain a solid with a particle size as homogeneous as possible. In a recent article published in Analytical and Bioanalytical Chemistry, researchers from the Tianjin Medical University at China have proposed a smart MIP monolith for the extraction of ketoprofen from milk samples.

In an old post entitled “Smart molecularly imprinted hydrogels for protein recognition”, we discussed the advantages of these materials that combine the selectivity enhancement of MIPs with the advantages of smart polymers. In short, a smart polymer is a porous polymeric network that may respond to external stimulus (mainly pH, ionic strength or temperature) with a change in its structure or dimension. This change can be used to control the uptake and release of the analytes with a negligible effect on the polymeric network that memorizes the imprinting state.

In the new article, the authors synthesized a monolith avoiding the crashing and sieving process and therefore improving the reproducibility of the material. A monolith is a one-block polymer comprising large pores (macropores) that favor the sample flow through the polymer and small pores (mesopores) that increase the superficial area of the network. The main challenge that the authors found in their development was the selection of the porogenic solvent. In fact, the low solubility of the thermo-responsive monomer in conventional solvents made necessary the use of dimethylsulfoxide (DMSO) as solvent although it provides the polymeric network with a low porosity. This shortcoming was avoided using an ionic liquid as modifier in the synthesis. The IL increases the porosity and permeability of the resulting polymer.

The smart-MIP showed selective molecular recognition towards the target analyte when it was compared with the non-imprinted polymer (NIP), synthesized in the absence of template. This selectivity was thermo-dependent; at temperatures lower than 35 ºC the MIP performance was superior to that showed by the NIP while at higher temperatures both polymers presented a more uniform behavior.

We recommend this article to our readers. The article describes the synthesis of the polymer, the optimization of that process, the characterization of the material and its final application for the extraction of ketoprofen from milk samples.

References
(1) Thermoresponsive ketoprofen-imprinted monolith prepared in ionic liquid. Link to the article

Comments

Post a Comment

Popular posts from this blog

Gold coated magnetic beads for electrochemical detection

By -
Image
This post summarizes an interesting article, recently accepted for publication in Analytical Chemistry, which presents an innovative use of magnetic beads. Researchers from the Osaka Prefecture University at Japan have proposed the synthesis of magnetic microbeads covered with a smooth gold layer that are used for the electrochemical detection of streptavidin (1). The synthesis, which is deeply described in the manuscript, consists of three well defined steps. First of all, the magnetic beads are introduced in a colloidal gold dispersion containing Au-nanoparticles (Au-NPs). Thanks to the opposite zeta potential of both materials (microbeads are negatively charged while Au-NPs present a positive charge), their assembly takes place by electrostatic interactions. However, the Au-NPs are not connected to each other and therefore the electrical resistance of the microbeads is too high. In a second step, the modified microbeads are dispersed in an aqueous medium containing HAuCl 4 as ...
Read more

Fabric phase sorptive extraction: a new generation green sample preparation strategy

By -
Image
by Dr. Abuzar Kabir, International Forensic Research Institute, Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, USA Fabric phase sorptive extraction (FPSE), the most recent member of the sorptive microextraction family, has innovatively incorporated both solid phase microextraction (SPME) and solid phase extraction (SPE) techniques into a single technology platform. FPSE utilizes permeable natural/synthetic fabrics e.g., cotton, polyester, fiber glass supports to chemically bind sol-gel hybrid inorganic-inorganic sorbents. A 5 cm2unit of coated fabric (2.5 cm x 2.0 cm) is typically used as the extraction media which can be inserted directly into the sample container. Extraction of the analytes is generally expedited by using a magnetic stir bar to diffuse the analyts into the sample matrix so that rapid mass transfer from the sample matrix to the extraction medium takes place.Once the mass transfer equilibrium between the FPSE media and...
Read more

Rotating Disk Sorptive Extraction

By -
Image
by Prof. Dr. Pablo Richter, Department of Inorganic and Analytical Chemistry, Faculty of Chemical and Pharmaceutical Sciences, University of Chile. The modern trends in analytical chemistry promote efficiency and green technology in sample preparation. In this context, our research team developed a new technique in 2009 that is capable of extracting pollutants from liquid samples on a rotating PTFE disk with one surface coated with an extraction phase [1]. The disk has embedded a miniature magnetic rod, which allows rotation. We have termed this procedure rotating-disk sorptive extraction (RDSE). RDSE is currently available in two configurations. In the classic version (Figure 1), the extraction phase is a polymeric film adhered to one side of the PTFE disk (configuration 1). In this configuration, polydimethylsiloxane (PDMS), nylon and octadecyl (C18) have been used as the sorptive material for the extraction of low-polarity analytes (Log Kow between 3 and 7) [1-12]. However...
Read more