Multianalyte Sensing Of Addictive Over-the-counter (otc) Drugs

A supramolecular sensor array composed of two fluorescent cucurbit[n]uril-type receptors (probe 1 and probe 2) displaying complementary selectivities was tested for its ability to detect and quantify drug-related amines. The fluorimetric titration of the individual probes showed highly variable and cross-reactive analyte-dependent changes in fluorescence. An excellent ability to recognize a variety of analytes was demonstrated in qualitative as well as quantitative assays. Importantly, a successful quantitative analysis of several analytes of interest was achieved in mixtures and in human urine. The throughput and sensitivity surpass those of the current state-of-the-art methods that usually require analyte solid-phase extraction (SPE). These results open up the opportunity for new applications of cucurbit[n]uril-type receptors in sensing and pave the way for the development of simple high-throughput assays for various drugs in the near future

Specific-Ion Effects on the Aggregation Mechanisms and Protein–Protein Interactions for Anti-streptavidin Immunoglobulin Gamma‑1

Non-native protein aggregation is common in the biopharmaceutical industry and potentially jeopardizes product shelf life, therapeutic efficacy, and patient safety. The present article focuses on the relationship(s) among protein–protein interactions, aggregate growth mechanisms, aggregate morphologies, and specific-ion effects for an anti-streptavidin (AS) immunoglobulin gamma 1 (IgG1). Aggregation mechanisms of AS-IgG1 were determined as a function of pH and NaCl concentration with sodium acetate buffer and compared to previous work with sodium citrate. Aggregate size and shape were determined using a combination of laser light scattering and small-angle neutron or X-ray scattering. Protein–protein interactions were quantified in terms of the protein–protein Kirkwood–Buff integral (<i>G</i>₂₂) determined from static light scattering and in terms of the protein effective charge (<i>Z</i>_eff) measured using electrophoretic light scattering. Changing from citrate to acetate resulted in significantly different protein–protein interactions as a function of pH for low NaCl concentrations when the protein displayed positive <i>Z</i>_eff. Overall, the results suggest that electrostatic repulsions between proteins were lessened because of preferential accumulation of citrate anions, compared to acetate anions, at the protein surface. The predominant aggregation mechanisms correlated well with <i>G</i>₂₂, indicating that ion-specific effects beyond traditional mean-field descriptions of electrostatic protein–protein interactions are important for predicting qualitative shifts in protein aggregation state diagrams. Interestingly, while solution conditions dictated which mechanisms predominated, aggregate average molecular weight and size displayed a common scaling behavior across both citrate- and acetate-based systems

Bending stiffness of biological membranes: What can be measured by neutron spin echo?

Mell M, Moleiro LH, Hertle Y, et al. Bending stiffness of biological membranes: What can be measured by neutron spin echo? The European Physical Journal E. 2013;36(7): 75.Large vesicles obtained by the extrusion method represent adequate membrane models to probe membrane dynamics with neutron radiation. Particularly, the shape fluctuations around the spherical average topology can be recorded by neutron spin echo (NSE). In this paper we report on the applicable theories describing the scattering contributions from bending-dominated shape fluctuations in diluted vesicle dispersions, with a focus on the relative relevance of the master translational mode with respect to the internal fluctuations. Different vesicle systems, including bilayer and non-bilayer membranes, have been scrutinized. We describe the practical ranges where the exact theory of bending fluctuations is applicable to obtain the values of the bending modulus from experiments, and we discuss about the possible internal modes that could be alternatively contributing to shape fluctuations