Dynamics and mechanism of dimer dissociation of photoreceptor UVR8

Photoreceptors are a class of light-sensing proteins with critical biological functions. UVR8 is the only identified UV photoreceptor in plants and its dimer dissociation upon UV sensing activates UV-protective processes. However, the dissociation mechanism is still poorly understood. Here, by integrating extensive mutations, ultrafast spectroscopy, and computational calculations, we find that the funneled excitation energy in the interfacial tryptophan (Trp) pyramid center drives a directional Trp-Trp charge separation in 80 ps and produces a critical transient Trp anion, enabling its ultrafast charge neutralization with a nearby positive arginine residue in 17 ps to destroy a key salt bridge. A domino effect is then triggered to unzip the strong interfacial interactions, which is facilitated through flooding the interface by channel and interfacial water molecules. These detailed dynamics reveal a unique molecular mechanism of UV-induced dimer monomerization.

Homeopathy emerging as nanomedicine

Background: Homeopathy is a time-tested two-century old empirical system of healing. Homeopathic medicines are prepared through a characteristic process known as potentization, where serial dilutions are performed with strong strokes at each step of dilution. Homeopathy is controversial because most medicines do not contain one single molecule of the corresponding starting-substance. Aim: To investigate a possible nanoscience mechanism of action of homeopathic medicines. Methodology: Ultra-pure samples were prepared and were examined under scanning (SEM) and transmission electron microscope (TEM) along with selected area nanodiffraction (SAD) and energy-dispersive X-ray analysis (EDX). Also trace element analysis (TEA) for silicon was performed. Results: Homeopathic medicines showed not to be ‘nothing’, but exhibited nanoparticles and conglomerates of them, which had crystalline nature and were rich in silicon. Conclusions: During the violent strokes involved in potentization, information arising from the serially diluted starting-substance might be encrypted by epitaxy on silicon-rich crystalline nanoparticles present in the resulting homeopathic medicine. The ‘size’ of the information encrypted on nanoparticles might vary together with the degree of dilution. As homeopathic medicines exhibit healing effects, these nanoparticles along with the interfacial water on their surface might carry this information - which biological systems are able to identify - to the target. As various forms of silica are known to interact with proteins and cells of the immune system, homeopathy might represent a nanomedicine system. Possible confirmation, however, requires further research in materials and interfacial water.

Phytic Acid Doped Polypyrrole as a Mediating Layer Promoting Growth of Prussian Blue on Cotton Fibers for Solar-Driven Interfacial Water Evaporation

Phytic acid doped polypyrrole (PPy) as a mediating layer was in-situ coated on cotton fibers (CFs) to promote the growth of Prussian blue (PB) and construct the PB/PPy@CFs composite. The results showed that the proper amounts of PA doped PPy in-situ generated significantly promoted the growth of PB on CFs, the PB deposition ratio increased from 12.29% (PB@CFs) to 32.4% (PB/PPy@CFs), and the growth of PB on PPy@CFs could be completed in 4 h. Scanning electron microscopy (SEM) showed that the PB particles with perfect nano cubic structure were formed in the composite. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) showed that both PB and PPy were successfully deposited on CFs. The PB/PPy@CFs composite had excellent light absorption, hydrophilicity, wettability, and photothermal property, and the surface could be heated up to 81.5 °C under one sun illumination. The PB/PPy@CFs composite as a photothermal conversion material was used for solar-driven interfacial water evaporation, the water evaporation rate was 1.36 kg·m−2·h−1 at the optical concentration of 1 kW·m2, and the corresponding photothermal conversion efficiency increased from 81.69% (PB@CFs) to 90.96% (PB/PPy@CFs).