Supramolecular self-associating amphiphiles: determination of molecular self-association properties and calculation of critical micelle concentration using a high-throughput, optical density based methodology.

Supramolecular self-associating amphiphiles are a class of amphiphilic salt, the anionic component of which is 'frustrated' in nature, meaning multiple hydrogen bonding modes can be accessed simultaneously. Here we derive critical micelle concentration values for four supramolecular self-associating amphiphiles using the standard pendant drop approach and present a new high-throughput, optical density measurement based methodology, to enable the estimation of critical micelle concentrations over multiple temperatures. In addition, we characterise the low-level hydrogen bonded self-association events in the solid state, through single crystal X-ray diffraction, and in polar organic DMSO-d6 solutions using a combination of 1H NMR techniques. Moving into aqueous ethanol solutions (EtOH/H2O or EtOH/D2O (1 : 19 v/v)), we also show these amphiphilic compounds to form higher-order self-associated species through a combination of 1H NMR, dynamic light scattering and zeta potential studies.

High-throughput characterisation of supramolecular gelation processes using a combination of optical density, fluorescence and UV-Vis absorption measurements.

Herein, we showcase the use of high-throughput microplate reader methodologies for the characterisation of supramolecular gels. We demonstrate how UV-Vis absorption, optical density and fluorescence measurements can selectively define gel fibre assembly/disassembly processes, casting a new light on the construction of these materials.

Impact of Naja nigricollis Venom on the Production of Methaemoglobin.

Snakebite envenomation is an affliction currently estimated to be killing upwards of 100,000 people annually. Snakebite is associated with a diverse pathophysiology due to the magnitude of variation in venom composition that is observed worldwide. The haemolytic (i.e., lysis of red blood cells) actions of snake venoms are well documented, although the direct impact of venoms on haemoglobin is not fully understood. Here we report on the varied ability of a multitude of snake venoms to oxidise haemoglobin into methaemoglobin. Moreover, our results demonstrate that the venom of an elapid, the black necked spitting cobra, Naja nigricollis, oxidises oxyhaemoglobin (Fe2+) into methaemoglobin (Fe3+) in a time- and concentration-dependent manner that is unparalleled within the 47 viper and elapid venoms evaluated. The treatment of venom with a reducing agent, dithiothreitol (DTT) is observed to potentiate this effect at higher concentrations, and the use of denatured venom demonstrates that this effect is dependent upon the heat-sensitive proteinaceous elements of the venom. Together, our results suggest that Naja nigricollis venom appears to promote methaemoglobin production to a degree that is rare within the Elapidae family, and this activity appears to be independent of proteolytic activities of venom components on haemoglobin.