A biosensor for the detection of triazine- and phenylurea-type herbicides was constructed using isolated Photosystem II (PS II) complexes as a biosensing element. PSII isolated from the thermophilic cyanobacterium Synechococcus elongatus was immobilized on the surface of a screen-printed sensor composed of a graphite working electrode and Ag/AgCl reference electrode deposited on a polymeric substrate. The biosensor was mounted in a flow microcell with illumination. The principle of the detection was based on the fact that herbicides selectively block PSII electron transport activity in a concentration-dependent manner. Changes of the activity were registered amperometrically as the rate of photoreduction of an artificial electron acceptor. The setup resulted in a reusable herbicide biosensor with a good stability (half-life of 24 h) and limit of detection of approximately 10(-9) M for diuron, atrazine and simazine.

Background: Ameloblastin plays a key role in the complex biomineralization process that forms tooth enamel, the hardest tissue of the body. Results: Ameloblastin self-associates into ribbon-like supramolecular structures via a short segment encoded by exon 5. Conclusion: Ameloblastin self-association may be essential for correct structural organization and mineralization of the enamel in vivo. Significance: The results provide molecular insight into biology of tooth enamel formation.

The dendrimer chemistry reported offers a route to synthetic target molecules with spherical shape, well-defined surface chemistries and dimensions that match the size of virus particles. The largest target, a generation 13 dendrimer comprising triazines linked by diamines, is stable across ranges of concentration, pH, temperature, solvent polarity and in the presence of additives. This dendrimer theoretically, presents 16384 surface groups and has a molecular weight exceeding 8.4 million Daltons. Transmission electron and atomic force microscopies, dynamic light scattering, and computation reveal a diameter of approximately 30 nm. The target is synthesized through an iterative divergent approach using a monochlorotriazine macromonomer providing two generations of growth per synthetic cycle. Fidelity in synthesis is supported by evidence from NMR spectroscopy, mass spectrometry, and high pressure liquid chromatography.

Recombinant ligands derived from small protein scaffolds show promise as robust research and diagnostic reagents and next generation protein therapeutics. Here, we derived high-affinity binders of human interferon gamma (hIFNγ) from the three helix bundle scaffold of the albumin-binding domain (ABD) of protein G from Streptococcus G148. Computational interaction energy mapping, solvent accessibility assessment, and in silico alanine scanning identified 11 residues from the albumin-binding surface of ABD as suitable for randomization. A corresponding combinatorial ABD scaffold library was synthesized and screened for hIFNγ binders using in vitro ribosome display selection, to yield recombinant ligands that exhibited K(d) values for hIFNγ from 0.2 to 10 nM. Molecular modeling, computational docking onto hIFNγ, and in vitro competition for hIFNγ binding revealed that four of the best ABD-derived ligands shared a common binding surface on hIFNγ, which differed from the site of human IFNγ receptor 1 binding. Thus, these hIFNγ ligands provide a proof of concept for design of novel recombinant binding proteins derived from the ABD scaffold.