Electroanalytical and bioelectroanalytical systems based on metal and semiconductor nanoparticles

Metal, semiconductor and magnetic particles act as functional units for electroanalytical applications. Metal nanoparticles provide three important functions for electroanalysis. These include the roughening of the conductive sensing interface, the catalytic properties of the nanoparticles permiting their enlargement with metals and the amplified electrochemical detection of the metal deposits and the conductivity properties of nanoparticles at nanoscale dimensions that allow the electrical contact of redox-centers in proteins with electrode surfaces. Also, metal and semiconductor nanoparticles provide versatile labels for amplified electroanalysis. Dissolution of the nanoparticle labels and the electrochemical collection of the dissolved ions on the electrode followed by the stripping-off of the deposited metals represents a general electroanalytical procedure. These unique functions of nanoparticles were employed for developing electrochemical gas sensors, electrochemical sensors based on molecular- or polymer-functionalized nanoparticle sensing interfaces, and for the construction of different biosensors including enzyme-based electrodes, immunosensors and DNA sensors. Semiconductor nanoparticles enable the photoelectrochemical detection of analytes. Several studies have revealed the photocurrent generation by enzyme-mediated processes and as a result of DNA hybridization. Magnetic particles act as functional components for the separation of biorecognition complexes and for the amplified electrochemical sensing of DNA or antigen/antibody complexes. Also, electro-catalytic and bioelectrocatalytic processes at electrode surfaces are switched by means of functionalized magnetic particles and in the presence of an external magnet.