# High-Efficiency Adsorption of SARS-CoV-2 Spike 1 Protein by Plasma-Modified Porous Polymers
## 1 Introduction  
A sudden outbreak of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus (SARS-CoV-2) affected more than 600 million people worldwide and caused more than 6 million deaths, triggering extensive research activities aimed at preventing and treating coronavirus diseases [1; 2]. At present, the global epidemic situation is still at a high level, and the novel coronavirus (SARS-CoV-2) continues to mutate. The 'Omicron' variant has significantly enhanced its transmission ability and increased its escape ability, and it has replaced other variants to become the absolutely dominant epidemic strain in the world [3]. Therefore, it is particularly necessary to develop purification technologies that can effectively block virus transmission and remove low levels of virus in indoor air and wastewater. Adsorption is a method that uses adsorbents to accumulate and concentrate pollutants in air and water to remove them [4]. Virus adsorbents can use the attractive interaction between the adsorbent and the virus adsorbent to achieve virus separation and removal [5]. Previously reported virus adsorbents can be classified as inorganic adsorbents, inorganic-organic hybrid adsorbents and organic adsorbents [5; 6]. Common inorganic adsorbents areclays (kaolinite, montmorillonite and bentonite) [6], which generally have a low adsorption efficiency for viruses. Cellulose nanofibers enriched with \(\alpha\)-Fe\({}_{2}\)O\({}_{3}\) nanoparticles are organic-inorganic hybrid materials with the ability to adsorb viruses [7]. The main organic adsorbents are polymers, such as polysaccharides (anionic polysaccharide sulfate and cationic chitosan) [8; 9; 10; 11], and resins [12]. These virus adsorbents have different properties, but all of them show certain defects in practical applications, such as expensive equipment and operation costs, the difficulty of recycling adsorbents, and an ease in causing secondary pollution. Therefore, it is urgent to develop new virus adsorption materials with a high adsorption performance and low price, which can be applied to the isolation and removal of viruses worldwide. At present, the research on the adsorption of SARS-CoV-2 focuses on its S protein, because the specific interaction between S protein and materials determines the applicability of virus adsorption materials [13]. However, due to the low expression of the protein, it cannot be obtained in large quantities. Thus, in recent years, multiscale modeling, an innovative computational technique, has been considered to investigate the interaction between proteins and materials, so as to explore the adsorption mechanism between viruses and materials [14]. For instance, [PERSON] et al. [15] used all-atom molecular dynamics simulations to find that the adhesion of S1 protein over polystyrene was stronger than other materials and that adsorption was mainly driven by hydrophobicity and \(\pi\)-\(\pi\) interactions. [PERSON] et al. [13] predicted that the long-range interaction between S protein and the polymer surface is weaker than covalent or ionic bond energy by using a combination of molecular mechanics and dynamic simulation. [PERSON] et al. [16] employed high-speed atomic force microscopy to monitor the adsorption of recombinant SARS-CoV-2 spike protein S1 on the surface of oxide materials, suggesting that the adsorption of S1 protein on the oxide surface was mainly due to electrostatic interaction. These simulations provide a theoretical basis for protein and virus adsorption, but more practical experiments are needed to verify the adsorption mechanism and apply it to virus adsorption and removal. Currently, macroporous polymer resin has been applied to adsorb pollutants because of its low cost, stable chemical structure, abundant pores and large specific surface area [17; 18; 19].