Effects of Ionic Strength on the Morphology, Scattering, and Mechanical Response of Neurofilament-Derived Protein Brushes.

Protein brushes not only play a key role in the functionality of neurofilaments but also have wide applications in biomedical materials. Here, we investigate the effect of ionic strength on the morphology of protein brushes using continuous-space self-consistent field theory. A coarse-grained multiblock charged macromolecular model is developed to capture the chemical identity of amino acid sequences. For neurofilament heavy (NFH) brushes at pH 2.4, we predict three morphological regimes: swollen brushes, condensed brushes, and coexisting brushes, which consist of both a dense inner layer and a diffuse outer layer. The brush height predicted by our theory is in good agreement with the experimental data for a wide range of ionic strengths. The dramatic height decrease is a result of the electrostatic screening-induced transition from the overlapping state to the isolated state of the coexisting brushes. We also studied the evolution of the scattering and mechanical responses accompanying the morphological change. The oscillation in the reflectivity spectra characterizes the existence and microstructure of the inner condensed layer, whereas the shoulder in the force spectra signifies a swollen morphology.

Waste Biomass-Derived Carbon Anode for Enhanced Lithium Storage.

Due to increased populations, there is an increased demand for food; thus, battery electrode materials created from waste biomass provide an attractive opportunity. Unfortunately, such batteries rarely sustain capacities comparable to current state-of-the-art technologies. However, an anode synthesized from waste avocado seeds provides high cycling stability over 100 cycles and provides comparable capacity to graphite, around 315 mAh g-1 at 100 mA g-1 current density, and readily outperforms graphene in terms of both stability and capacity. This novel electrode provides such capacities as an amorphous carbon without the use of any additives or doped heteroatoms by utilizing capacitance-driven mechanisms to contribute to 54% of its lithium-ion storage. This allows the waste biomass-derived anode to overcome its low apparent diffusion coefficient of 4.38 × 10-11 cm2 s-1. By creating battery anodes from avocado seeds, waste streams can be redirected into creating valuable, renewable energy storage resources.