11 research outputs found
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><sub>22</sub>) determined
from static light scattering and in terms of the protein effective
charge (<i>Z</i><sub>eff</sub>) 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><sub>eff</sub>. 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><sub>22</sub>, 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