Two-dimensional vibronic spectroscopy of molecular aggregates: Trimers, dimers, and monomers

The two-dimensional (2D) vibronic spectroscopy of molecular trimers is studied theoretically. The solution of the time-dependent Schrödinger equation is carried out with the multi-configurational time-dependent Hartree (MCTDH) method which allows for an efficient propagation of the multi-component wave functions. 2D-spectra are calculated for H- and J-type aggregates incorporating one or two vibrational modes for each monomer. In performing calculations for monomer, dimer, and trimer systems, it is documented how the vibronic structure of the 2D-spectrum changes upon aggregation. This is of importance for the characterization of aggregation behavior being influenced by experimental conditions such as temperature or concentration

A SPR-based immunosensor for the detection of isoproturon.

The proof of principle of a reusable surface plasmon resonance (SPR)-based immunosensor for the monitoring of isoproturon (IPU), a selective and systemic herbicide, is presented. The detecting rat monoclonal anti-isoproturon antibody (mAb IOC 7E1) was reversibly immobilized through the use of a capture mouse anti-rat (kappa-chain) monoclonal antibody (mAb TIB 172), which was covalently immobilized on the sensor chip surface. Such strategy features a controlled binding of the captured detecting antibody as well as facilitates the surface regeneration. The capture of the anti-IPU mAb by the antibody (TIB 172) coated sensor surface could be carried out up to 120 times (immobilization/regeneration cycles) without any evidence of activity loss. With a high test midpoint and a low associated SPR signal, the direct detection format was shown to be unsuitable for the routine analysis of isoproturon. However, the limit of detection (LOD) could be easily enhanced by using a strategy based on a surface competition assay, which improved all immunosensor parameters. Moreover, the sensitivity and working range of the indirect format were found to be dependent on the surface density of the anti-IPU mAb IOC 7E1. As expected for competitive formats, the lowest surface coverage (0.5 ng/mm(2)) allowed a lower detection of the herbicide isoproturon with a calculated LOD of 0.1 microg/l, an IC(50) (50% inhibition) of 5.3+/-0.6 microg/l, and a working range (20-80% inhibition) of 1.3-16.3 microg/l

Multi-parameter determination of TNFα, PCT and CRP for point-of-care testing.

A proof of concept for the simultaneous multi-parameter determination of three inflammation and sepsis parameters-TNFα, PCT and CRP-using a compact optical immunosensor is demonstrated. Harmonized assay conditions revealed standard curves with test midpoints (IC(50)) of 380 µg L(-1) for TNFα, 2300 µg L(-1) for PCT, and 2645 µg L(-1) for CRP

Development and characterization of new rat monoclonal antibodies for procalcitonin.

The development of selective and sensitive biological recognition elements, e.g., antibodies, for the detection of relevant blood markers is a great challenge in the field of biosensors. In this context, five new rat monoclonal antibodies (mAbs) for procalcitonin (PCT), a marker for bacterial infection and sepsis, were developed and characterized. One mAb, PROC1 3G3, was used as capture antibody. Four mAbs, PROC4 6C6, PROC4 6B2, PROC4 1G3, and PROC4 1D6, were used as detection mAbs, either as Protein G-purified or as biotinylated mAbs. A surface plasmon resonance (SPR) biosensor was used to characterize the antigen-antibody biomolecular interactions. The capture mAb (PROC1 3G3) has an equilibrium dissociation constant (K (D)) of 3.42 x 10(-8) M. All four detection mAbs (PROC4 6C6, PROC4 6B2, PROC4 1G3, and PROC4 1D6) are of high affinity (K (A) = 2.81-6.11 x 10(8) M(-1); K (D) = 1.64-3.56 x 10(-9) M) and have moderate dissociation rate constants (k (d) = 1.70-2.40 x 10(-3) s(-1)). Four different sandwich enzyme-linked immunosorbent assays (ELISAs) with standards of human recombinant (hr) PCT, using PROC1 3G3 as capture mAb and PROC4 mAbs as detection mAbs, respectively, led to highly specific determinations of PCT without cross-reactivities to calcitonin and katacalcin. The lower limits of quantification (LLOQ) for hrPCT (in 40 mM phosphate-buffered saline (PBS), pH 7.6) with these assays ranged from 2.3 to 12.8 microg L(-1). In addition, sandwich ELISAs were set up with biotinylated PROC4 mAbs, and with hrPCT in 4% human serum albumin (diluted 1:10 in 40 mM PBS, including 1:5 (v/v) LowCross Buffer(R)). The LLOQs of these sandwich assays ranged from 4.1 to 6.0 microg L(-1) and were thus much closer together for the different assays. With the latter assay setup (PROC1 3G3 as capture mAb, PROC4 6C6-biotin as detection mAb) a first collection of five serum samples was determined (healthy volunteers, unspiked, and spiked). Recovery rates for the spiked samples ranged from 98.3 to 115.7%. The newly developed anti-PCT mAbs should find broad applications in immunosensors for point-of-care diagnostics of sepsis and systemic inflammation processes

3-Pyridylacetonitrile-ligated 11-vertex rhodathiaboranes: synthesis, characterization, and X-ray crystal structure

<div><p>The reaction between the 11-vertex rhodathiaborane [8,8-(PPh₃)₂-<i>nido</i>-8,7-RhSB₉H₁₀] (<b>1</b>) and 3-pyridylacetonitrile affords the hydrorhodathiaborane [8,8,8-(PPh₃)₂H-9-(3-Py-CH₂CN)-<i>nido</i>-8,7-RhSB₉H₉] (<b>2</b>) in good yield. Treatment of this cluster with ethylene leads to the formation of red, [1,1-(PPh₃)(<i>η</i>^<i>2</i>-C₂H₄)-3-(3-Py-CH₂CN)-<i>closo</i>-1,2-RhSB₉H₈] (<b>3</b>). Both 11-vertex polyhedral boron-based clusters have been characterized by multielement NMR spectroscopy. In addition, (<b>3</b>) has been analyzed by single-crystal X-ray diffraction analysis and is only the second ethylene-ligated metalla-heteroborane to be characterized in the solid state. The molecular structure of this cluster is based on an octadecahedron. In the crystal lattice, the individual clusters form layers supported by short edge-to-face <i>π</i>-interactions between the phenyl rings of neighboring molecules.</p></div

A new procalcitonin optical immunosensor for POCT applications.

A new immunosensor for the determination of procalcitonin was developed. A sandwich assay format was implemented on a polymethylmetacrylate optical biochip, opportunely shaped in order to obtain several flow channels and potentially suitable for point of care testing applications. The sandwich format makes use of two new rat monoclonal antibodies. The capture antibody was covalently immobilised on the surface of the plastic chip, and the detection antibody was labelled with DY647 dye. Different combinations of capture and detection antibodies were investigated, and particular attention was devoted in order to avoid the nonspecific adsorption. A limit of detection of 0.088 mg L-1 was achieved within the working range of 0.28-50 mg L-1 in buffer samples. The assay was also implemented in human serum, and 0.2 and 0.7-25 mg L-1 were the attained limit of detection and working range, respectively