Monitoring insulin fibrillation kinetics using chromatographic analysis.

Insulin is a small protein widely used to treat patients with diabetes and is a commonly used model for protein fibrillation studies. Under specific conditions, such as low pH and high temperature, insulin monomers aggregate to form fibrils. This aggregation is problematic for manufacturing and storage of insulin. The thioflavin T (ThT) assay is commonly used to study amyloid fibrillation but suffers from several limitations, such as the effect of protein concentration, the size of the amyloid fibrillar bundles, competitive binding, and fibril aggregation, all of which hinder precise quantitative analysis. Here, we present a method for studying the kinetics of insulin fibrillation utilizing ultra-performance liquid chromatography (UPLC). This method enables the quantitative detection of soluble insulin components, including chemically modified components. The formation of a deamidated species could be monitored at the early stage of fibrillation, and this species was likely included in the fibrils. In addition, in the presence of inhibitors known to compete with ThT for binding to fibrils, UPLC analysis showed the disappearance of soluble components even though the ThT assay did not indicate the presence of fibrils. These results suggest that the UPLC-based analysis presented here can complement the ThT assay for investigating the kinetics of protein fibrillation.

Near-unity angular anisotropy of circularly polarized luminescence from microspheres of monodispersed chiral conjugated polymers.

A microsphere, assembled from a chiral π-conjugated polymer with narrow polydispersity, features a well-organized twisted-bipolar structure and exhibits highly biased circularly polarized luminescence (CPL). The CPL emitted toward the equatorial direction is 61-fold greater than that emitted along the zenith direction, which is the highest anisotropy among existing microscopic CPL emitters.

Near perfect head-to-head selectivity on the supramolecular photocyclodimerisation of 2-anthracenecarboxylate with self-organised gemini surfactant bilayers.

Silicificated self-organised crystalline bilayers of gemini surfactants were used as reaction templates for the supramolecular regioselective [4+4] photocyclodimerisation of 2-anthracenecarboxylate in water. A near perfect head-to-head cyclodimer selectivity, up to 97% at room temperature, was achieved with accelerated rate.