Molecularly Imprinted Nanoparticles (NanoMIPs) Selective for Proteins: Optimization of a Protocol for Solid-Phase Synthesis Using Automatic Chemical Reactor.

Molecularly imprinted polymer nanoparticles (nanoMIPs) are receiving broad interest as robust and highly selective synthetic receptors for a variety of molecules. Due to their stability, inexpensive synthesis and easy implementation, they are considered a promising alternative to antibodies in sensors, diagnostics and separation applications. The most challenging targets for the production of synthetic receptors are proteins due to their fragile nature and the multitude of possible binding sites in their structure. Herein, we describe the modification and optimization of the protocol for synthesis of nanoMIPs with specificity for proteins using the prototype of an automated solid-phase synthesizer. Using an automated system gives an advantage for the simple, fast and fully controlled, reproducible production of nanoMIPs. The molecular imprinting in the reactor is performed using a template covalently immobilized on a solid support, in mild conditions suitable for preserving protein native structure. The validation of the protocol was made by assessing the ability to regenerate a solid-phase, and by measuring affinity and specificity of nanoparticles. As a model protein, we have chosen trypsin since its enzymatic activity can be easily monitored by using a commercial colorimetric assay. Different protocols were tested for their ability to improve the yield of high affinity nanoparticles in the final elution.

Direct potentiometric quantification of histamine using solid-phase imprinted nanoparticles as recognition elements.

A new potentiometric sensor based on molecularly imprinted nanoparticles produced via the solid-phase imprinting method was developed. For histamine quantification, the nanoparticles were incorporated within a membrane, which was then used to fabricate an ion-selective electrode. The use of nanoparticles with high affinity and specificity allowed for label-free detection/quantification of histamine in real samples with short response times. The sensor could selectively quantify histamine in presence of other biogenic amines in real wine and fish matrices. The limit of detection achieved was 1.12×10(-6)molL(-1), with a linear range between 10(-6) and 10(-2)molL(-1) and a response time below 20s, making the sensor as developed a promising tool for direct quantification of histamine in the food industry.

Rational design and chromatographic evaluation of histamine imprinted polymers optimised for solid-phase extraction of wine samples.

This article reports on the computational design, development and application of a molecularly imprinted polymer (MIP) with specific affinity towards histamine. Computational modelling was used to screen a monomer library in order to select the monomers able to form the strongest complex with the target analyte. These were subsequently used for MIP synthesis by radical polymerisation initiated by UV. MIPs were then evaluated by liquid chromatography and solid phase extraction (SPE) and best MIP behaviour was observed when itaconic acid was used as functional monomer. Finally, after optimisation of the polymer composition, MIPs were used as adsorbents for SPE and clean-up of histamine in wine samples. The proposed histamine extraction method with the MIP-SPE cartridge was found to be reproducible (<5% RSD) and accurate (93-99% recovery) and provided clear wine extracts. The described methodology is simple and fast and is suitable for the selective histamine extraction and its subsequent quantification by HPLC-DAD from complex matrices such as wine samples.