Copper nanoparticles (CuNPs) are widely used and inevitably released into aqueous environments, causing ecological and health risks. Ubiquitous natural organic matter (NOM) might affect the copper release behaviors from CuNPs and their toxicity. This work aims to elucidate how NOM affects copper release from CuNPs, with a focus on the impacts of NOM properties and the NOM-CuNPs interaction mechanism. The copper release kinetics and different copper fractions induced by representative NOMs were characterized. The presence of NOM led to a more dispersive state of CuNPs clusters. Copper release mainly resulted from complexation reactions between CuNPs and functional groups of NOM. Humic substances were more effective in releasing copper than sodium alginate and bovine serum albumin, due to a higher amount of functional groups and lower molecular weight , which facilitated the contact and complexion reactions. Chlorination treatment of NOM significantly decelerated copper release due to the destruction of functional groups and less attachment of NOM. However, the copper releasing ability of humic acid was not substantially affected by Ca 2+ -induced coagulation. This study provides better understanding about the persistence and transformation of CuNPs in aquatic environments.
Abstract Stability of engineered nanoparticles in aquatic environment is an essential parameter to evaluate their fate, bioavailability, and potential toxic effects toward living organisms. As CuO NPs enter the wastewater systems, they will encounter extracellular polymeric substances (EPS) from microbial community before directly interacting with bacterial cells. EPS may play an important role in affecting the stability and the toxicity of CuO NPs in aquatic environment. In this study, the influences of flocculent sludge-derived EPS, as well as model protein (BSA) and natural polysaccharides (alginate) on the dissolution kinetics and colloidal stability of CuO NPs were investigated. Results showed that the presence of NOMs strongly suppressed CuO NPs aggregation, confirmed by DLS, zeta potentials, and TEM analysis. The enhanced stability of CuO NPs in the presence of EPS and alginate were attributed to the electrostatic combined with steric repulsion, while the steric-hindrance effect may be the predominant mechanism retarding nano-CuO aggregation for BSA. Higher degrees of copper release were achieved with the increasing concentrations of NOMs. EPS are more effective than alginate and BSA in releasing copper, probably due to the abundant functional groups and the excellent metal-binding capacity. The ratio of free-Cu 2+ /total dissolved Cu significantly decreased in the presence of EPS, indicating that EPS may affect the speciation and Cu bioavailability in aqueous environment. These results may be important for assessing the fate and transport behaviors of CuO NPs in the environment as well as for setting up usage regulation and treatment strategy. Graphical Abstract
Yutang Ding,Kun Tang,Yuheng Zhang,Linxin Yang,Binjing Zhang,Xin Zhang,Jian Wang
Tongue injuries are among the most common acute soft tissue injuries encountered in oral clinical practice. Suturing, as the conventional treatment, often leads to tissue distortion and tension-induced collagen over-deposition, resulting in scarring and restricted tongue mobility. Sutures are also prone to microbial accumulation and provoke inflammation as foreign bodies. In this study, a hydrogel patch specifically designed for the tongue’s moist, frequently moving, and richly vascularized environment was developed for better healing of tongue injuries. Briefly, a chitosan-polyacrylic acid-tannic acid hydrogel matrix is loaded with Cu-MOF to form the CPTCu hydrogel, ensuring stable binding and controlled release of copper, while maintaining mechanical compliance with tongue tissue for continuous protection. The CPTCu hydrogel exhibited excellent biocompatibility, achieving free radical scavenging rate of 73.6% and bactericidal rate of over 99.5%. Compared with suturing, CPTCu hydrogel significantly reduced collagen volume by 35.9% and enhanced angiogenesis by 103.2%, as well as effectively promoted regeneration of local muscle fibers in a rat tongue wound model. These results demonstrate that CPTCu hydrogel is a promising candidate for optimized scarless tongue healing.
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