Surface molecular imprinted membranes as a “gate” for selective transdermal release of chiral drug amlodipine

Molecular imprinting is a technique that is used to create artificial receptors by the formation of a polymer network around a template molecule. This technique has proven to be particularly effective for molecules with low molecular weight (<1500 Da), and during the past five years the number of research articles on the imprinting of larger (bio)templates is increasing considerably. However, expanding the methodology toward imprinted materials for selective recognition of proteins, DNA, viruses and bacteria appears to be extremely challenging. This paper presents a critical analysis of data presented by several authors and our own experiments, showing that the molecular imprinting of proteins still faces some fundamental challenges. The main topics of concern are proper monomer selection, washing method/template removal, quantification of the rebinding and reproducibility. Use of charged monomers can lead to strong electrostatic interactions between monomers and template but also to undesired high aspecific binding. Up till now, it has not been convincingly shown that electrostatic interactions lead to better imprinting results. The combination of a detergent (SDS) and AcOH, commonly used for template removal, can lead to experimental artifacts, and should ideally be avoided. In many cases template rebinding is unreliably quantified, results are not evaluated critically and lack statistical analysis. Therefore, it can be argued that presently, in numerous publications the scientific evidence of molecular imprinting of proteins is not convincing. Copyright © 2011 Elsevier Ltd. All rights reserved.

In the present study, acid catalysed cross-linking of poly vinyl alcohol (PVA) with varying concentrations of glutaraldehyde was analyzed and the cross-linked PVAs were utilized as membrane separators in single chambered microbial fuel cells (MFCs). In the present study, acid catalysed cross-linking of poly vinyl alcohol (PVA) with varying concentrations of glutaraldehyde was analyzed and the cross-linked PVAs were utilized as membrane separators in single chambered microbial fuel cells (MFCs). PVA with varying concentrations (1, 2, 4 and 6%) of glutaraldehyde has resulted in a respective 2.8, 5.6, 32 and 34% of degree of cross-linking in PVA1, PVA2, PVA3 and PVA4 membranes. Due to the reduction of available free volume in membranes, progressive improvements in membrane rigidity with impeded membrane porosity were observed with increasing cross-link densities. In succession, proton conductivities of 7.53 × 10 −3 , 8.4 × 10 −4 , 1.2 × 10 −4 and 4.5 × 10 −5 S cm −1 were observed from the respective PVA1, PVA2, PVA3, and PVA4 membranes. The increased cross-link density enhanced the mechanical strength but reduced other membrane properties such as water uptake and proton conductivities of the membranes. Further, the cast membranes were assembled as MEAs in open air cathode MFCs where, a maximum power and current density of 119.13 ± 6 mW m −2 and 447.81 ± 18 mA m −2 were observed from PVA3 fitted MFC, using mixed firmicutes as biocatalysts. With increased cross-link density, higher ohmic resistances were observed in MFCs, but due to lower oxygen diffusion in the anode, increased performance was observed from highly cross-linked membranes. Electrogenic firmicutes revealed an overall ∼93.45% of COD removal in 27 days of operation, indicating the efficiency of the respective membranes as separators in MFCs. In general, the study depicts the relevance of different acid catalysed cross-linked PVA membranes in bio-energy conversion from microbial fuel cells.