Epitope-Cavities Generated by Molecularly Imprinted Films Measure the Coincident Response to Anthrax Protective Antigen and Its Segments

Abstract

A molecularly imprinted film was fabricated, in the presence of epitope-peptides, onto a quartz crystal microbalance (QCM) chip. These five peptides are known linear or conformational epitopes of the anthrax protective antigen PA(83). Imprinting resulted in an epitope-cavity with affinity for the corresponding template. With the use of a basic monomer, the binding-effect was further enhanced increasing the affinity to nanomolar levels. The affinities of the peptide to their corresponding molecularly induced polymers (MIPs) were more closely related to the molecular weight of the analyte than to the number of residues. All epitope-cavities differentiated their epitope region on the protective antigen PA(83) as well as the corresponding furin cleavage fragments PA(63) and PA(20). The QCM chip differential response to the protective antigen fragment was observed in the picomolar range, thus demonstrating a method to manipulate protein on the surface with defined orientation.

Epitope Imprinting Approach to Monitor Diseases

“…Tai et al synthesized the piezoelectric MIP sensor for this antigen through epitope imprinting on QCM electrode surface (Table 1). This epitope-imprinted QCM platform can be used for immunoassay of bacterial antigens [34]. Peptide imprinted MIP nanoparticles (NPs) were able to catalyse the conformational conversion of the recognized peptide and promote peptide structuration [35].…”

Protein-imprinted materials: rational design, application and challenges

“…These epitope imprinting approaches are applicable even in organic solvents used for traditional small-molecule imprinting, because small peptides are not subject to the major conformational and degradation problems which occur in whole-protein imprinting [33][34][35][36].…”

“…Chou et al prepared creatine kinase and ovalbumin-imprinted materials by "micro-contact imprinting" with MAA as monomer [44,45]. In Tai's studies, acrylic acid was also used with acrylamide to produce 2D MIP films for a variety of target proteins on quartz crystal microbalance sensors [34,46,47]. On the basis of the experimental results, better protein recognition capacity could be obtained with acrylamide or its derivatives as the principal functional monomer, accompanied by a small amount of a strongly basic or acidic co-monomer.…”

“…The epitope strategy overcomes this difficulty to some extent, but the problem arises of how to choose the specific fragments. Recently, the characteristic fragments chosen are usually the N or C-terminal 5-10 amino acids [20,34,81]. For improved selective recognition, the choice of rational templates should be taken into account at the mechanism level, or with the aid of computational methods.…”

Biosensing Applications of Molecularly Imprinted Nanomaterials

“…Based on this approach, this group recently fabricated another QCM-MIP sensor in the presence of epitope peptides for the detection of the protective antigen of anthrax [200]. Those five peptides, such as (N-Acr-l-Cys-NHBn) 2 , are linear or conformational epitopes of the anthrax-protective antigen PA 83 , which made the resulting epitope-cavity show high affinity for the corresponding template, as shown in Tables 9.3 and 9.4.…”