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Many nanoproteases contain tetravalent metal ions and catalyze peptide‐bond hydrolysis only at high temperature (60 °C). Here, we report a new and effective strategy to explore nanoproteases from nanoparticles containing low valent metal ions. We found that flower‐like CuCoO2 nanoparticles (CuCoO2 NPs) containing low valent Cu+ possessed excellent catalytic activity towards selective cleavage of peptide bonds with hydrophobic residues in bovine serum albumin (BSA) at room temperature. CuCoO2 NPs exhibited excellent stability and had great reusability. CuCoO2 NPs also hydrolyzed heat‐denatured and surfactant‐denatured BSA. Mechanism analysis revealed that the high Lewis acidity of Co3+ and the low valence of Cu+ were both essential for the high protease activity of CuCoO2 NPs. The flower‐like structure of CuCoO2 NPs and the strong nucleophilicity of Cu+‐bound hydroxyl endow them with excellent catalytic performance. The findings open a new way for the design and discovery of high‐efficiency nanoproteases. [ABSTRACT FROM AUTHOR]

Inspired by the mussel adhesion protein, dopamine was used to prepare polydopamine (PDA)-coated polyurethane sponge (PDA-PUS) via self-polymerization reaction. Halloysite nanotubes (HNTs) were grafted with γ -aminopropyltriethoxysilane (APTES). The new organic-inorganic hybrid adsorption material (HNTs@PUS) was fabricated by covalent link of APTES-grafted HNTs and PDA-PUS through Schiff base reaction/Michael addition. The as-prepared HNTs@PUS showed much higher mechanical stability and compressive property than polyurethane sponge (PUS). HNTs@PUS had 7.7, 7.1, 1.7 and 8.5 times adsorption capacity of PUS for Congo red (CR), Methyl orange (MO), Rhodamine 6 G (R6G) and heavy metal ion Cr(VI), respectively. HNTs@PUS had a fast adsorption rate and most of CR, MO, R6G and Cr(VI) were adsorbed by HNTs@PUS within 20 min. In addition, HNTs@PUS maintained 70.3%, 66.5%, 67.3% and 77.4% of its adsorption capacity for CR, MO, R6G and Cr(VI), respectively, after 5 cycles of regeneration. HNTs@PUS could be easily recovered to avoid secondary contamination. Besides, using HNTs@PUS as adsorbents, a continuous flow adsorption device was developed, through which anionic and cationic dyes and heavy metal ion could be continuously and effectively removed from the flowing solution. These results demonstrated that HNTs@PUS had potentially ideal attributes for use as adsorbents in the ultrafast, high efficiency and large-scale removal of anionic and cationic dyes and heavy metal ions from wastewaters. The fabrication strategy not only solved the problem of the poor recyclability and low permeability of HNTs, but also greatly improved the adsorption capacity of PUS, which might accelerate the application of natural "green" HNTs in wastewater treatment. [Display omitted] • HNTs@PUS has been fabricated by covalent link of HNTs and PUS. • HNTs@PUS has more seven times adsorption capacity of PUS for CR, MO and Cr(VI). • Most of CR, MO, R6G and Cr(VI) were adsorbed by HNTs@PUS within 20 min. • HNTs@PUS maintains over 67% of the adsorption capacity for dyes/Cr(VI) after 5 cycles. • HNTs@PUS can be used in a continuous flow system against emerging contaminants. [ABSTRACT FROM AUTHOR]