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Bacterial infections originating from food, water, and soil are widely recognized as significant global public health concerns. Biofilms are implicated in approximately two-thirds of bacterial infections. In recent times, nanomaterials have emerged as potential agents for combating biofilms and bacteria, with many of them being activated by light and H2O2 to generate reactive oxygen species (ROS). However, this energy-consuming and extrinsic substrate pattern poses many challenges for practical application. Consequently, there is a pressing need to develop methods for the untriggered generation of ROS to effectively address biofilm and bacterial infections. In this study, we investigated the oxidase-like activity of the Co,N-doped carbon dot (CoNCD) nanozyme, which facilitated the oxidation of ambient O2 to generate 1O2 in the absence of light and H2O2 supplementation; this resulted in effective biofilm cleavage and enhanced bactericidal effects. CoNCDs could become a potential candidate for wound healing and treatment of acute peritonitis in vivo, which can be primarily attributed to the spontaneous production of ROS. This study presents a convenient ROS generator that does not necessitate any specific triggering conditions. The nanozyme properties of CoNCDs exhibit significant promise as a potential remedy for diseases, specifically as an anti-biofilm and anti-bacterial agent. [ABSTRACT FROM AUTHOR]

Bacterial infections have been a major threat to human health. Especially, Gram-negative (G−) bacterial infections have been an increasing problem worldwide. The overuse of antibiotics leads to an emergence of drug resistance, and thus the development of novel antimicrobial agents is important, particularly against G− bacteria. Nanozymes use reactive oxygen species (ROS) to kill bacteria, reducing the risk of bacterial resistance and providing new opportunities to meet the challenges of strain selectivity. Here, we synthesized NiCo layered double hydroxide (LDH) nanozymes, which exhibit selective antibacterial activity based on their peroxide-like (POD-like) activity. To obtain the highest antibacterial activity, the POD-like activity of NiCo LDH nanozyme was further optimized by tuning the ratio of nickel and cobalt, and Ni4Co6 LDHs showed the highest POD activity and antibacterial activity. More importantly, Ni4Co6 LDHs can achieve selective sterilization of G− bacteria due to their electrostatic adsorption and hydrophilic interactions with the bacterial cell wall. Animal experiments further indicated that the healing of G− bacteria-infected wounds was effectively promoted without damaging their normal biological tissues. In conclusion, we provide a selective antibacterial agent through a simple strategy, which provides a new direction for the application of nanozymes. [ABSTRACT FROM AUTHOR]

Five unimolecular channels with different lengths are presented. The varying length of these channels has significant impact on their transmembrane transport properties, which are directly correlated with their antimicrobial activity and inversely correlated with their haemolytic toxicity. By further structural optimization, these new channels could reach high antimicrobial activity and very low haemolytic toxicity, with the potential to serve as systemic antibiotics. [ABSTRACT FROM AUTHOR]

A series of pH-sensitive, cation-selective hydrazide macrocyclic channels have been synthesized. The macrocyclic channels bear multiple carboxyls in the inner cavity, which have a significant impact on their membrane-incorporation ability and NH4+ transport activity. Moreover, the K+/Cl− selectivities of the macrocyclic channels can be tuned by the pH value of the electrolyte. [ABSTRACT FROM AUTHOR]

In the present study, a simple strategy was developed for Ni/Co layered double hydroxides (LDHs) as a substitute for natural peroxidase. The obtained Ni/Co LDHs exhibited ease of preparation, low-cost, and water-solubility; importantly, this material showed high catalytic activity in neutral pH solutions (phosphate buffer, Tris–HCl buffer, and even water). Benefitting from Ni/Co LDHs having a similar pH and temperature with specificity oxidase, such as glucose oxidase, choline oxidase, acetylcholinesterase, etc., a novel one-step method for a biosensor was developed in water. Glucose detection was selected as an application model system to evaluate the performance of this method, which showed a linear detection range from 0.5 μM to 100 μM with a detection limit (DL) of 0.1 μM. We also extended the one-step method to detect acetylcholine (ACh) by taking advantage of the specific catalytic reaction of acetylcholinesterase (AChE) and choline oxidase (ChOx). The linear detection range was from 10 μM to 150 μM with the DL of 1.62 μM. The proposed method had ease of operation, simple steps, and was rapid for glucose and ACh detection in real samples. On the basis of these advantages and virtues, Ni/Co LDHs could become attractive nanozymes in biotechnology and bioassays, and create a great influence on the next generation of enzyme mimetic systems. [ABSTRACT FROM AUTHOR]