Most of the ongoing projects aimed at the development of specific therapies and vaccines against COVID-19 use the SARS-CoV-2 spike (S) protein as the main target. The binding of the spike protein with the ACE2 receptor (ACE2) of the host cell constitutes the first and key step for virus entry. During this process, the receptor binding domain (RBD) of the S protein plays an essential role, since it contains the receptor binding motif (RBM), responsible for the docking to the receptor. So far, mostly biochemical methods are being tested in order to prevent binding of the virus to ACE2. Here we show, with the help of atomistic simulations, that external electric fields of easily achievable and moderate strengths can dramatically destabilise the S protein, inducing long-lasting structural damage. One striking field-induced conformational change occurs at the level of the recognition loop L3 of the RBD where two parallel beta sheets, believed to be responsible for a high affinity to ACE2, undergo a change into an unstructured coil, which exhibits almost no binding possibilities to the ACE2 receptor. We also show that these severe structural changes upon electric-field application also occur in the mutant RBDs corresponding to the variants of concern (VOC) B.1.1.7 (UK), B.1.351 (South Africa) and P.1 (Brazil). Remarkably, while the structural flexibility of S allows the virus to improve its probability of entering the cell, it is also the origin of the surprising vulnerability of S upon application of electric fields of strengths at least two orders of magnitude smaller than those required for damaging most proteins. Our findings suggest the existence of a clean physical method to weaken the SARS-CoV-2 virus without further biochemical processing. Moreover, the effect could be used for infection prevention purposes and also to develop technologies for in-vitro structural manipulation of S. Since the method is largely unspecific, it can be suitable for application to other mutations in S, to other proteins of SARS-CoV-2 and in general to membrane proteins of other virus types.

We analyzed the formation of the aluminum (Al) nanoparticles (NPs) with triangular shape obtained by ablating Al bulk in liquid using pulses with different durations (5 ns, 200 ps, and 30 fs) and wavelengths (355 nm, 800 nm, and 1064 nm). We report three stages of synthesis and aging of Al NPs: Formation, transformation, and stable stage. The NPs prepared by different pulses are almost identical at the initial stage. The effects of duration and wavelength of the ablation pulses on the aging of NPs are revealed. Pulse duration is determined to be essential for morphological transformation of NPs, while pulse wavelength strongly influences particle sizes. NPs produced by ultra-short pulses have smaller sizes and narrow size distribution. We demonstrate that oxidation and hydrolysis of Al in water are the results of ablation for all pulse durations and wavelengths, which also strongly modify the preferable reaction path of NPs in water, thus affecting the composition and morphology of triangle NPs. The results of modeling of the NPs generation in water due to a 50 ps laser pulse interacting with a thick Al target are presented. Water-based effects in the formation of NPs, their evolution, and solidification are considered from the mechanical and thermophysical points of view. The detailed analysis of the modeling results allowed for determination of the main mechanism responsible for the ablation process followed by the NPs formation.