Nanostructured artificial receptor materials with unprecedented hierarchical structure for determination of human serum albumin (HSA) are designed and fabricated. For that purpose a new hierarchical template is prepared. This template allowed for simultaneous structural control of the deposited molecularly imprinted polymer (MIP) film on three length scales. A colloidal crystal templating with optimized electrochemical polymerization of 2,3'-bithiophene enables deposition of an MIP film in the form of an inverse opal. Thickness of the deposited polymer film is precisely controlled with the number of current oscillations during potentiostatic deposition of the imprinted poly(2,3'-bithiophene) film. Prior immobilization of HSA on the colloidal crystal allows formation of molecularly imprinted cavities exclusively on the internal surface of the pores. Furthermore, all binding sites are located on the surface of the imprinted cavities at locations corresponding to positions of functional groups present on the surface of HSA molecules due to prior derivatization of HSA molecules with appropriate functional monomers. This synergistic strategy results in a material with superior recognition performance. Integration of the MIP film as a recognition unit with a sensitive extended-gate field-effect transistor (EG-FET) transducer leads to highly selective HSA determination in the femtomolar concentration range.
16 March 2016 in Advances in Condensed Matter Physics
The fabrication of low-resistance and thermal stable ohmic contacts is important for realization of reliable SiC devices. For then-type SiC, Ni-based metallization is most commonly used for Schottky and ohmic contacts. Many experimental studies have been performed in order to understand the mechanism of ohmic contact formation and different models were proposed to explain the Schottky to ohmic transition for Ni/SiC contacts. In the present review, we summarize the last key results on the matter and post open questions concerning the unclear issues of ohmic contacts ton-type SiC. Analysis of the literature data and our own experimental observations have led to the conclusion that the annealing at high temperature leads to the preferential orientation of silicide at the heterointerface (0001)SiC//(013)-Ni2Si. Moreover, we may conclude that onlyδ-Ni2Si grains play a key role in determining electrical transport properties at the contact/SiC interface. Finally, we show that the diffusion barriers with free diffusion path microstructure can improve thermal stability of metal-SiC ohmic contacts for high-temperature electronics.