Preparation Of Gold Nanorods And Their Application For Biosensor

Hydrogen peroxide determination plays an important role in the improvement oflife quality[1-7].The development of H₂O₂biosensor for monitoring and understandingbiological process is important due to health requirement.In recent years, the focus on spectroscopic applications of Au nanoparticles aremuch more, because they have intense plasmon absorption bands in the visiblewavelength regime. Au NRs exhibit two different plasmonic modes includingtransverse and longitudinal modes[9-14].The transverse and longitudinal surfaceplasmonic modes are corresponding to electronic oscillation of the plasmonperpendicular and parallel to the rod length direction, respectively. For thelongitudinal mode, plasmon oscillation is parallel to the major axis of the nanocrystalsso that the longitudinal resonance wavelength increases with increasing aspect ratio.H₂O₂is a powerful oxidizing agent. H₂O₂show high electrochemical potentialthan Au NRs[15,16]. Therefore, H₂O₂should affect the LSPR peaks of Au NRs bychange their aspect ratio, which can be applied as an alternative method for detectingH₂O₂. However, H₂O₂is produced in many oxjdase-catalyzed reactions，includingenzymes such as glucose oxidase, cholesterol oxidase, etc．The detection of theconcentration of H₂O₂can be employed to measure the concentration of many targetsamples，which are the substrates of the oxidases mentioned above．This makes itpossible to develop biosensors for various substances such as glucose，etc.Au NRs are prepared by silver ion-assisted seed-mediated method, which arecharacterized using UV-vis spectroscopy, transmission electron microscopy. Thelongitudinal plasmon of Au nanorods has high catalytic ability so that hydrogenperoxide can be decomposed by them. As a result, Au NRs may be shortened throughan oxidation reaction with hydrogen peroxide. During shortening Au NRs, the LSPRpeak is seen to blue shift. In this process, the LSPR band of Au NRs displays thedependence of spectral shift on concentration of H₂O₂. It provide a more simple andsensitive sensor in detecting H₂O₂. Besides, Au nanorods are being used in thefabrication of optical glucose biosensors and expected to enhance the performances ofbiosensors. As the concentration of glucose changed, the LSPR peak of Au nanorodsis changed. This fact can be used in the nanorod-enhancing glucose biosensor.