Immobilization of biomolecules on nanostructured films for biosensing

This paper brings an overview of the use of nanostructured films in several types of biosensors, with emphasis on the advantageous control of molecular architecture which is typical of the layer-by-layer (LbL) and Langmuir-Blodgett films. Following introductory sections on film fabrication and detection methods, we concentrate on the immobilization of biomolecules on these nanostructured films used in units for biosensing. Important contributions in the literature in biosensors based on electrochemical and optical measurements are highlighted. Furthermore, a discussion is presented on how the concept of electronic tongues has been extended to biosensing, which resulted in increased sensitivity and selectivity. The integration of sensing units with micro-electronics is commented upon, especially in the context of using field-effect transistors (FETs) for biosensing. Examples of LbL and LB films containing proteins, lipids, metallic nanoparticles and carbon nanotubes, which are used for detecting a variety of analytes, will be provided. The prospects for clinical diagnosis with such biosensors are also assessed. Throughout the review, emphasis is placed on the importance of control of molecular architecture, particularly with synergistic combination of organic and inorganic materials. For example, nanostructured films containing capped gold nanoparticles or carbon nanotubes exhibited enhanced performance in biosensing. It is hoped that this survey may assist researchers in choosing materials, molecular architectures, and detection principles, which may be tailored for specific applications.