Isotherm parameters and intraparticle mass transfer kinetics on molecularly imprinted polymers in acetonitrile/buffer mobile phases

Multi-objective optimization for the economic production of d-psicose using simulated moving bed chromatography

The biocatalytic production of rare carbohydrates from available sugar sources rapidly gains interest as a route to acquire industrial amounts of rare sugars for food and fine chemical applications. Here we present a multi-objective optimization procedure for a simulated moving bed (SMB) process for the production of the rare sugar d-psicose from enzymatically produced mixtures with its epimer d-fructose. First, model parameters were determined using the inverse method and experimentally validated on a 2-2-2-2 lab-scale SMB plant. The obtained experimental purities (PUs) were in excellent agreement with the simulated data derived from a transport-dispersive true-moving bed model demonstrating the feasibility of the proposed design. In the second part the performance of the separation was investigated in a multi-objective optimization study addressing the cost-contributing performance parameters productivity (PR) and desorbent requirement (DR) as a function of temperature. While rare sugar SMB operation under conditions of low desorbent consumption was found to be widely unaffected by temperature, SMB operation focusing on increased PR significantly benefited from high temperatures, with possible productivities increasing from 3.4kg(Lday)(-1) at 20°C to 5kg(Lday)(-1) at 70°C, indicating that decreased selectivity at higher temperatures could be fully compensated for by the higher mass transfer rates, as they translate into reduced switch times and hence higher PR. A DR/PR Pareto optimization suggested a similar but even more pronounced trend also under relaxed PU requirements, with the PR increasing from 4.3kg(Lday)(-1) to a maximum of 7.8kg(Lday)(-1) for SMB operation at 50°C when the PU of the non-product stream was reduced from 99.5% to 90%. Based on the in silico optimization results experimental SMB runs were performed yielding considerable PRs of 1.9 (30°C), 2.4 (50°C) and 2.6kg(Lday)(-1) (70°C) with rather low DR (27L per kg of rare sugar produced) on a lab-scale SMB installation.

Characterization of the Binding Properties of Molecularly Imprinted Polymers

The defining characteristic of the binding sites of any particular molecularly imprinted material is heterogeneity: that is, they are not all identical. Nonetheless, it is useful to study their fundamental binding properties, and to obtain average properties. In particular, it has been instructive to compare the binding properties of imprinted and non-imprinted materials. This chapter begins by considering the origins of this site heterogeneity. Next, the properties of interest of imprinted binding sites are described in brief: affinity, selectivity, and kinetics. The binding/adsorption isotherm, the graph of concentration of analyte bound to a MIP versus concentration of free analyte at equilibrium, over a range of total concentrations, is described in some detail. Following this, the techniques for studying the imprinted sites are described (batch-binding assays, radioligand binding assays, zonal chromatography, frontal chromatography, calorimetry, and others). Thereafter, the parameters that influence affinity, selectivity and kinetics are discussed (solvent, modifiers of organic solvents, pH of aqueous solvents, temperature). Finally, mathematical attempts to fit the adsorption isotherms for imprinted materials, so as to obtain information about the range of binding affinities characterizing the imprinted sites, are summarized.

Molecular imprinting science and technology: a survey of the literature for the years 2004-2011

Herein, we present a survey of the literature covering the development of molecular imprinting science and technology over the years 2004-2011. In total, 3779 references to the original papers, reviews, edited volumes and monographs from this period are included, along with recently identified uncited materials from prior to 2004, which were omitted in the first instalment of this series covering the years 1930-2003. In the presentation of the assembled references, a section presenting reviews and monographs covering the area is followed by sections describing fundamental aspects of molecular imprinting including the development of novel polymer formats. Thereafter, literature describing efforts to apply these polymeric materials to a range of application areas is presented. Current trends and areas of rapid development are discussed.

Chiral recognition applications of molecularly imprinted polymers: a critical review

Molecular imprinting technology offers the unique opportunity to tailor chiral stationary phases with predefined chiral recognition properties by employing the enantiomers of interest as binding-site-forming templates. Added advantages, such as ease of preparation, chemical robustness, low-cost production, and the possibility of shaping molecularly imprinted polymers (MIPs) in various self-supporting formats, render them attractive materials for a broad range of chiral recognition applications. In this review a critical overview on recent developments in the field of MIP-based chiral recognition applications is given, focusing on separation techniques and molecular sensing. Inherent limitations associated with the use of enantioselective MIP materials in high-performance separation techniques are outlined, including binding site heterogeneity and slow mass transfer characteristics. The prospects of MIP materials as versatile recognition elements for the design of enantioselective sensor systems are highlighted.