Multiplexed Native Mass Spectrometry Determination of Ligand Selectivity for Fatty Acid-Binding Proteins.

Although multiple approaches for characterizing protein-ligand interactions are available in target-based drug discovery, their throughput for determining selectivity is quite limited. Herein, we describe the application of native mass spectrometry for rapid, multiplexed screening of the selectivity of eight small-molecule ligands for five fatty acid-binding protein isoforms. Using high-resolution mass spectrometry, we were able to identify and quantify up to 20 different protein species in a single spectrum. We show that selectivity profiles generated by native mass spectrometry are in good agreement with those of traditional solution-phase techniques such as isothermal titration calorimetry and fluorescence polarization. Furthermore, we propose strategies for effective investigation of selectivity by native mass spectrometry, thus highlighting the potential of this technique to be used as an orthogonal method to traditional biophysical approaches for rapid, multiplexed screening of protein-ligand complexes.

Au nanoparticle in situ decorated RGO nanocomposites for highly sensitive electrochemical genosensors.

A novel hybrid nanocomposite formed by RGO flakes, surface functionalized by 1-pyrene carboxylic acid (PCA), densely and uniformly in situ decorated by Au NPs, that are concomitantly coordinated by the PCA carboxylic group, and by an aromatic thiol used as the reducing agent in the synthesis, both ensuring, at the same time, a stable non-covalent NPs anchorage to the RGO flakes, and an efficient interparticle electron coupling along the NP network onto the RGO, is reported. The obtained solution processable hybrid material is used to modify Screen-Printed Carbon Electrodes (SPCEs). The hybrid modified SPCEs, functionalized with a thiolated DNA capture probe, are tested in a streptavidin-alkaline-phosphatase catalyzed assay, for the detection of the biotinylated miRNA-221, and for its determination in spiked human blood serum samples. The proposed genosensor demonstrates a high sensitivity (LOD of 0.7 pM), attesting for a performance comparable with the most effective reported sensors. The enhanced sensitivity is explained in terms of the very fast heterogeneous electron transfer kinetics, the concomitant decrease of the electron transfer resistance at the electrode/electrolyte interface, the high electroactivity and the high surface area of the nanostructured hybrid modified SPCEs that provide a convenient platform for nucleic acid biosensing.