Understanding the Intrinsic Water Wettability of Hexagonal Boron Nitride.

The water wettability of hexagonal boron nitride (hBN) has attracted a lot of research interest in the past 15 years. Experimentally, the static water contact angle (WCA) has been widely utilized to characterize the intrinsic water wettability of hBN. In the current study, we have investigated the effect of airborne hydrocarbons and defects on both static and dynamic WCAs of hBN. Our results showed that the static WCA is impacted by defects, which suggests that previously reported static WCAs do not characterize the intrinsic water wettability of hBN since the state-of-the-art hBN samples always have relatively high defect density. Instead, we found that the advancing WCA of freshly exfoliated hBN is not affected by the defects and airborne hydrocarbons. As a result, the advancing WCA on freshly exfoliated hBN, determined to be 79 ± 3°, best represents the intrinsic water wettability of hBN. A qualitative model has been proposed to describe the effect of airborne hydrocarbons and defects on the static and dynamic WCA of hBN, which is well supported by the experimental results. The finding here has important implications for the water wettability of 2D materials.

Herbalome of Chandraprabha vati, a polyherbal formulation of Ayurveda prevents fibrillation of lysozyme by stabilizing aggregation-prone intermediate state.

Lysozyme amyloidosis (ALys) is caused by the deposition of amyloid-like fibrils of lysozyme in the tissues of the gastrointestinal tract, liver and kidneys. The treatment/prevention of ALys is not known yet. Therefore, searching for therapeutic agents for amyloidosis is of great value. In this study, we have examined the ability of the aqueous extract of herbalome (thirty herbal components) of Chandraprabha vati (EHCV), a polyherbal Ayurvedic formulation, to prevent fibrillation of lysozyme. Transmission electron microscopy and multiple biophysical techniques were used to examine the processes. We found complete inhibition of the fibrillation by EHCV, whereas none of the thirty ingredients of EHCV was able to prevent the reaction, solely. We also found the EHCV induced and stabilized secondary structures of aggregation-prone state (APS) of lysozyme. Moreover, an increase in the secondary structure and stability of APS were found to correlate with the inhibition reaction. We conclude that EHCV modulates the structure and stability of APS and converts it into an aggregation resistant state (ARS). We hypothesized that herbal components of Ayurvedic formulation may provide a combination of molecules, which could efficiently prevent aggregation reaction.

The physical basis of fabrication of amyloid-based hydrogels by lysozyme.

The fabrication of amyloid-based hydrogels has attracted remarkable attention within the field of materials science and technology. These materials have a multitude of potential applications in the biomaterials field such as developing scaffolds for tissue engineering, drug delivery and hygiene products. Despite the potential new applications of these materials, the physical nature of their assembly is not well understood. In this study, we have investigated how the conformation of the amyloid precursor state (I) is formed and correlated with the assembly of amyloid-based hydrogels. A transparent hydrogel was fabricated at pH 7.4 by cooling of the temperature-induced unfolded state of hen egg white lysozyme (HEWL). The completely unfolded state (U) at the gelation concentration of HEWL was obtained around 90 °C in the presence of tris(2-carboxyethyl)phosphine (TCEP), with a TCEP/HEWL molar ratio of 4 : 1. The characterization of the hydrogel showed that it was composed of an amyloid fibril-like material. The physical nature of its assembly was examined in detail and it was found that the hydrogel formation reaction was a three-step, four-states process (U → I → F → H). We concluded that the properties of the pre-molten globule state (I) of the protein correlated only with the fibrillation process, whereas the assembly of the fibrils into an hydrogel was found to be almost independent of the I state. Thus, the study presented here provides a complete biophysical insight into the pathway of lysozyme hydrogel assembly.