In this paper, we demonstrated an efficient and robust route to the preparation of well-defined molecularly imprinted polymer based on reversible addition-fragmentation chain transfer (RAFT) polymerization and click chemistry. The alkyne terminated RAFT chain transfer agent was first synthesized, and then click reaction was used to graft RAFT agent onto the surface of silica particles which was modified by azide. Finally, imprinted thin film was prepared in the presence of 2,4-dichlorophenol as the template. The imprinted beads were demonstrated with a homogeneous polymer films (thickness of about 2.27 nm), and exhibited thermal stability under 255°C. The as-synthesized product showed obvious molecular imprinting effects towards the template, fast template rebinding kinetics and an appreciable selectivity over structurally related compounds.
"The presence of a reactive surface in the 'grafting from' approach allows a greater control of the polymerization process, above all in terms of length and density of surface polymer chains and for these reasons its use has been recently increased. On this basis, in order to efficiently develop thin controlled polymeric layers, in recent years, various surface molecular imprinting techniques based on 'iniferter' [Ruckert et al., 2002; Perez-Moral and Mayes, 2007; Barahona et al., 2010], 'reversible addition-fragmentation chain transfer' [Titirici and Sellergren, 2006; Pan et al., 2009; Chang et al., 2010] and 'atom transfer radical polymerization' [Wei et al., 2005; Zu et al., 2009; Sasaki et al., 2010] have been developed. Besides these methods to prepare controlled imprinted thin layers, a non-conventional approach to surface molecular imprinting has been reported [Matsui et al., 2002; Li et al., 2005]. "
[Show abstract][Hide abstract] ABSTRACT: Molecularly imprinted polymers have been successfully used as selective stationary phases in capillary electrophoresis. Notwithstanding, this technique suffers from several drawbacks as the loss of molecular recognition properties in aqueous media and the lack of feasibility for imprinted systems directed towards highly polar templates soluble in aqueous environments only. Thus, the preparation of imprinted polymers for highly polar, water-soluble analytes, represents a challenge. In this work, we present an innovative approach to overcome these drawbacks. It is based on a surface molecular imprinting technique that uses preformed macromonomers as both functional recognition elements and cross-linking agents. A poly-2-hydroxyethyl-co-methacrylic acid linear polymer was grafted from the surface of silica capillaries. The grafted polymer was exhaustively esterified with methacrylic anhydride to obtain polyethylendimethacrylate-co-methacrylic acid linear chains. Then, as a proof of concept, an adequate amount of a very polar template like penicillin V was added in a hydro-organic mixture, and a thin layer of imprinted polymer was obtained by cross-linking the polymer linear chains. The binding behaviour of the imprinted and non-imprinted capillaries was evaluated in different separation conditions in order to assess the presence of template selectivity and molecular recognition effects. The experimental results clearly show that this innovative kind of imprinted material can be easily obtained in very polar polymerization environments and that it is characterized by enhanced molecular recognition properties in aqueous buffers and good selectivity towards the template and strictly related molecules.
[Show abstract][Hide abstract] ABSTRACT: In this study, the magnetic yeast composites (mag–yeast) were successfully prepared by coating the chitosan layer containing γ-Fe2O3 nanoparticles onto the surface of the yeast. Then, the magnetic molecularly imprinted polymers (MMIPs) based on the mag–yeast were prepared by atom transfer radical polymerization (ATRP) which was occurred in mild reaction conditions. The MMIPs were characterized by Fourier transmission infrared spectrometry (FT-IR), scanning electron microscope (SEM), vibrating sample magnetometer (VSM), thermogravimetric analysis (TGA) and elemental analysis. The results demonstrated that spherical shaped MMIPs particles prepared via ATRP possessed magnetic property (Ms = 1.229 emu g−1) and magnetic stability (especially over the pH range of 5.0–11.0). The MMIPs were adopted as sorbents to selective recognition and separation of cefalexin (CFX). By the batch mode experiments, the results showed that adsorption behaviors of MMIPs were well described by the Freundlich isotherm and the pseudo-second-order kinetics. The MMIPs possessed excellent recognition capacity for CFX (36.86 mg g−1 at 298 K), and also exhibited outstanding selectivity for CFX over the other competitive compounds (such as sulfadiazine, tetracycline and ampicillin). Finally, the MMIPs were successfully applied to the selective solid phase extraction of CFX from the environmental samples.
Chemical Engineering Journal 08/2012; s 198–199:503–511. DOI:10.1016/j.cej.2012.05.106 · 4.32 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Background: Recent reports indicate that the sentinel node, defined as the first regional lymph node to receive lymphatic fluid from
the breast, accurately represents the metastatic status of the primary breast cancer. However, routine single section examination
of the regional nodes, including the sentinel node, underestimates the true incidence of metastases. The goal of this study
is to determine whether multiple sectioning of sentinel nodes will detect occult metastases in operable breast cancer.
Methods: Nineteen patients with invasive breast cancers were injected with technetium-99m sulfur colloid solution around the tumor
or at the biopsy site before lumpectomy and axillary lymph node dissection (ALND) or mastectomy. The labeled sentinel lymph
nodes (SLND) were bivalved, and a central section was taken for hematoxylin and eosin (H & E) examination. The sentinel nodes
of 13 patients, which were reported to be negative for metastases, were serially sectioned at 0.5-mm intervals and stained
with H & E and a cytokeratin stain, CAM 5.2.
Results: In the 13 node-negative patients, occult metastases were found in the sentinel nodes of 3 patients (23%). Two were seen on
H & E and one by cytokeratin stain. The mean numbers of SLND and ALND in this series were 2.6 and 12.5, respectively, and
the average number of sections for the two groups was 14 and 1, respectively.
Conclusion: Multiple sectioning of the sentinel node or nodes detects occult metastases and changes the staging of breast cancer.
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