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Martinez-Perdiguero J.,micro Microtechnologies Cooperative Research Center | Retolaza A.,micro Microtechnologies Cooperative Research Center | Retolaza A.,Micro NanoFabrication Unit | Bujanda L.,University of the Basque Country | And 2 more authors.
Talanta | Year: 2014

A simple method for the detection of TNF-alpha protein biomarker in human serum with great sensitivity has been developed using a surface plasmon resonance biosensor. Signal amplification based on a sandwich immunoassay including gold nanoparticles was used. Detection in serum proved to be challenging due to high undesirable non-specific binding to the sensor surface stemming from the matrix nature of the sample. After optimization of the assay parameters and, in the case of serum, of a sample dilution buffer to minimize the non-specific binding, very low limits of detection were achieved: 11.6 pg/mL (211 fM) and 54.4 pg/mL (989 fM) for spiked buffer and human serum respectively. The amplification steps with high affinity biotinylated antibodies and streptavidin-fuctionalized nanoparticles greatly enhanced the signal with the advantage of additional specificity. Due to its simplicity and sensitivity, the immunoassay has proved feasible to be used for detection of low concentration biomarkers in real samples. © 2013 Elsevier B.V.

Lizandara-Pueyo C.,University of Konstanz | Morant-Minana M.C.,University of Konstanz | Morant-Minana M.C.,Micro Microtechnologies Cooperative Research Center | Wessig M.,University of Konstanz | And 3 more authors.
RSC Advances | Year: 2012

The bottom-up synthesis of functional materials has become one of the most versatile tools of nanochemistry. It requires not only control over composition and particle size, but also over shape. The fine-control over shape demands an in-depth knowledge about the nucleation and growth of inorganic crystals in the homogeneous phase. A detailed, mechanistic study about the crystallization of zinc oxide is presented here. The findings can easily be transferred to other binary solids with significant ionic character and in particular to those adopting polar crystal classes. New insights about the role of anionic capping agents, cations and kinetic factors during crystallization are reported. One has to conclude that the influence of the cations, specifically the interplay between cation and anion is more significant than expected. Furthermore, low-molecular weight additives containing carboxylic groups are compared to macromolecular additives leading to unusual mesocrystals. Similarities to the concepts of biomineralization are discussed. Finally, a drastic enhancement of photocatalytic activity by several orders of magnitude could be observed for shape-engineered ZnO nanoparticles. © 2012 The Royal Society of Chemistry.

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