MIPs and Aptamers for Recognition of Proteins in Biomimetic Sensing

Abstract

Biomimetic binders and catalysts have been generated in order to substitute the biological pendants in separation techniques and bioanalysis. The two major approaches use either "evolution in the test tube" of nucleotides for the preparation of aptamers or total chemical synthesis for molecularly imprinted polymers (MIPs). The reproducible production of aptamers is a clear advantage, whilst the preparation of MIPs typically leads to a population of polymers with different binding sites. The realization of binding sites in the total bulk of the MIPs results in a higher binding capacity, however, on the expense of the accessibility and exchange rate. Furthermore, the readout of the bound analyte is easier for aptamers since the integration of signal generating labels is well established. On the other hand, the overall negative charge of the nucleotides makes aptamers prone to non-specific adsorption of positively charged constituents of the sample and the "biological" degradation of non-modified aptamers and ionic strength-dependent changes of conformation may be challenging in some application.

Keywords: SELEX; aptamers; aptasensors; biomimetic recognition elements; chemical sensors; in vitro selection; molecularly imprinted polymers.

Figure 1

Simplistic workflow of molecularly imprinted polymers (MIP)-preparation.

Figure 2

Number of publications on protein-imprinted (circles) and all molecularly imprinted (triangles, right axis) polymers, until the end of 2015 (generated by means of MIPdatabase [16]).

Figure 3

Schematic workflow of aptamer generation.

Figure 4

Number of publications subdivided to the search terms ‘aptamer protein’ (squares), ‘Aptamer protein + in vitro selection’ (triangles) and ‘aptamer’ (circles, right axis), until the end of 2015 (generated by means of Scopus [43]).

Figure 5

Surface imprinting approaches for the synthesis of MIP films for selective recognition of proteins: (A) Polymerization of a mixture of protein and monomer; (B) Binding of the protein to a self-assembled anchor layer for oriented immobilization of the protein prior to polymerization.