Biomimetic recognition elements

Electrocatalytic groups such as porphyrins and phthalocyanines that act as supramolecular hosts for different metals and mimic the active sites of various proteins are commonly used in amperometric sensors [66,67]. A biomimetic sensor based on an artificial enzyme or synzyme has been demonstrated [68]. The artificial enzyme used in this study was a synthetic polymer (quaternised polyethyleneimine containing 10% primary amines) which decarboxylated oxaloacetate. The product carbon dioxide was detected potentiometrically via a gas membrane electrode. 

MIMs are also included in this group, as their development was inspired by the instructional theory of antibody formation, and they have often been referred to as artificial antibodies . 

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The IUPAC definition may also be extended in respect to biomimetic recognition elements, e.g., aptamers and molecularly imprinted polymers, which are derived from biology (Table). 

Main types of biomolecular recognition elements used in affinity biosensors based on spectroscopy of guided modes include antibodies, nucleic acids and biomimetic materials. Antibodies are used most frequently because of their high affinity, versatility, and commercial availability. 

Kriz D, Ramstrom O, Svensson A, Mosbach K. Introducing biomimetic sensors based on molecularly imprinted polymers as recognition elements. Anal Chem 1995 67 2142-2144. 

It has been demonstrated that MIPs possess recognition and binding properties close to those of antibodies and enzymes, especially in organic media, and display higher stability than their natural counterparts. These properties suggest that MIPs can be suitable as recognition elements for chemical (biomimetic) sensors or biomimetic chips. 

A classification of the recognition elements used in sensors can be made on the basis of their physicochemical/biological/biomimetic origin and catalytic/non-cata-lytic nature (see Table 18.1). 

One of the reasons why biosensors have had only limited commercial success is the relative fragility of the recognition elements. Generally, they lack the robustness demanded by the market. The replacement of enzymes and antibodies with highly stable and robust MIPs could help overcome this problem. Figure 6.32 illustrates a general MIP biomimetic sensor where the MIP is bound to a transducing element via an interface. 

Nolte et al 46) produced an artificial enzyme based on the T4 replisome and applied it to the epoxidation of double bonds in synthetic polymers. Smith et al 51) reported that horseradish peroxidase catalyzes the oxidative polymerization of glucuronic acid. In recent literature, many biomimetic macromolecules with enzyme-like structures or functions have been reported including those that are dendrimers 64-66), those that have specified three-dimensional structures or recognition elements created by molecular imprinting 67), and other enzyme mimics 68). 

Kriz, D. Ramstrom, O. Svensson, A. Mosbach, K. Introducing Biomimetic Sensors Based on Molecularly Imprinted Polymers as Recognition Elements. Anal. Chem. 1995, 67, 2142-2144. 

Biological recognition element Classified into five different major categories. These categories include antibody/antigen, enzymes, nucleic acids/DNA/ RNA, cellular structures/cells, and biomimetic. The enzymes, antibodies, and... 

A.H. Kamel, ETC. Moreira and M.G.F. Sales, Biomimetic sensor potentiometric system for doxycycline antibiotic using a molecularly imprinted polymer as an artificial recognition element. Sensor Lett., 9 (5) 1654-1660, 2011. 

In the context of this book, the term bioactivity is mainly applied to polymers that incorporate elements capable of molecular biological recognition, such as peptide sequences serving as cell adhesion ligands and polyanionic sites that utilize electrostatic interactions for the biomimetic presentation of... 

Synthetic chemosensors incorporate a synthetically manufactured element for recognition. While biomimetic receptors have been prepared, with synthetic receptors mimicking the active sites of naturally occurring biological molecules, synthetic receptors can be designed entirely from first principles. 

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