No abstract

We describe the development, characterization, and biological testing of a new type of linear molecularly imprinted polymer (LMIP) designed to act as an anti-infective by blocking the quorum sensing (QS) mechanism and so abrogating the virulence of the pathogen Streptococcus pneumoniae. The LMIP is prepared (polymerized) in presence of a template molecule, but unlike in traditional molecular imprinting approaches, no cross-linker is used. This results in soluble low-molecular-weight oligomers that can act as a therapeutic agent in vitro and in vivo. The LMIP was characterized by mass spectrometry to determine its monomer composition. Fragments identified were then aligned along the peptide template by computer modeling to predict the possible monomer sequence of the LMIP. These findings provide a proof of principle that LMIPs can be used to block QS, thus setting the stage for the development of LMIPs a novel drug-discovery platform and class of materials to target Gram-positive pathogens.

The standard mechanism of molecular imprinting centers on the formation of a monomer−template complex in the prepolymerization mixture which remains trapped in the polymeric network following polymerization in the presence of a cross-linker. The release of the template leaves behind a binding site with functional groups "frozen" in a conformation complementary to the structure of the template and its analogues. Herein, we discuss the limitations of this model and present an alternative, in which imprinting is a result of dynamic interactions among the template, monomers, oligomers, and growing polymers in a solution. As a model, we have chosen the solid-phase synthesis of molecularly imprinted polymer (MIP) nanoparticles. Evidence is provided from the surface plasmon resonance-based binding analysis of MIP and "protoparticles", literature sources, and theoretical considerations. We conclude that the alternative mechanism may explain some behavioral inconsistency of the conventional model, including the impact of temperature, cross-linking, and computational molecular models, and describe some possibilities for improvement in MIP affinity and selectivity.

No abstract

Enzyme-linked immunosorbent assay (ELISA) is a widely used standard method for sensitive detection of analytes of environmental, clinical or biotechnological interest. However, ELISA has clear drawbacks related to the use of relatively unstable antibodies and enzyme conjugates, and need in several steps such as washing of non-bound conjugates and adding dye reagents. Herein we introduce a new completely abiotic assay where antibodies and enzymes are replaced with fluorescent molecularly imprinted polymer nanoparticles (nanoMIPs) and target-conjugated magnetic nanoparticles, which acted as both reporter probes and binding agents. The components of the molecularly imprinted polymer nanoparticles assay (MINA) are assembled in microtiter plates fitted with magnetic inserts. We have compared performance of new magnetic assay with MIP-based ELISA for the detection of methyl parathion (MP). Both assays have shown high sensitivity toward allowing detection of MP at picomolar concentrations without any cross-reactivity against chlorpyriphos and fenthion. The fully abiotic assays were also proven to detect analyte in real samples such as tap water and milk. Unlike ELISA-based systems the novel assay required no washing steps or addition of enzyme substrates, making it more user-friendly and suitable for high throughput screening.

No abstract

Molecularly imprinted polymer (MIP) nanoparticles, commonly referred to as 'plastic antibodies' or synthetic receptors, are polymeric materials with strong affi nity and selectivity for a particular chemical target. MIPs are regularly produced for use in sensors for monitoring food quality and environmental pollutants, and in the design of robust and affordable replacements for biological receptors, enzymes and antibodies in drug testing and assays. More recently the easy production of MIP nanoparticles has also permitted research relating to possible in vivo applications, primarily in drug delivery systems, toxin sequestration and pathogen inhibition. The strength of the interaction between the target and the polymer binding site is dependent on the particular monomers selected in synthesis of the MIP, and the relative concentrations of these in the pre-polymerization mixture. While computational approaches have been used to aid in MIP design previously, the methods adopted are often slow and simplistic, centring on observations of the template structure with a couple of functional monomers presumed to be appropriate. We present here an automated method of rapidly screening numerous functional monomers and effectively determining appropriate monomer ratios, while accounting for spatial discrimination in selection and dynamic parameters in optimization. Example are then given of effect MIP synthesis resulting from the protocol, and the benefi ts of this approach over competing methods are discussed.

This work assesses the fabrication of the first amperometric sensor based on electropolymerized MIPs for cocaine direct detection.