Biorecognition interactions

Recent developments in genosensor design with the advances in nanotechnology provide new tools in order to develop new techniques to monitor biorecognition and interaction events on solid surfaces and also in solution phase. Typical applications include environmental monitoring and control, and chemical measurements in the agriculture, food, and drug industries [8-17]. 

M. Wilchek, E.A. Bayer and O. Livnah, Essentials of biorecognition the (strept)avidin-biotin system as a model for protein-protein and protein-ligand interaction, Immunol. Lett., 103 (2006) 27-32. 

Considering the affinity between metal ions (i.e., Zn2+, Cu2+, Ni2+, and Co2+) and proteins another method to pattern proteins on gold surfaces by DPN was developed.130 This method utilizes Zn2+ ions (Zn(N03)2 6H20) that can be coordinated with MHDA, which can be patterned on gold by an AFM tip after passivation of the remaining gold areas with PEG-SH. The Zn-modified features can be subsequently reacted with the desired antibody. Biorecognition properties can be further studied by interaction with other proteins. 

Immunoassays, along with all other methods based on biorecognition, are a great achievement for the field of analjdical chemistry. The first area to benefit from the advantages of this technique is probably chnical analysis, where selective and sensitive determination of macromolecules is often necessary, as it is very difficult, or sometimes impossible to identify and quantify macromolecules by any alternative method. Recently, the immunoassay application field was extended, more or less successfiilly, to the determination of small molecules (below 1000 Da) as well. The acceptance of immunoassays is, however, relatively hmited in some fields, probably due to the differences between the classical analytical methods and immunoassays, the latter requiring special conditions of operation, characterization and data interpretation, due to the extraordinary nature of the antibody-antigen interaction, as well as that of many possible interfering reactions. 

Fig. 2. Liposome structure (A) Biorecognition elements can be covalently conjugated to or inserted into lipid bilayers through hydrophobic interactions (not to scale.) (B) The large internal volume of unilamellar vesicles can encapsulate hundreds of thousands of hydrophilic signaling molecules and provide for their stability. (C) Surfactant introduction can provide for instantaneous signal enhancement through release of encapsulants. Fluorophores encapsulated within liposomes at high concentrations undergo self-quenching, which is overcome upon release into the surrounding medium.

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