Construction and Activity Study of a Natural Antibacterial Patch Based on Natural Active Substance-Green Porous Structures.

Bacterial infections are a serious threat to human health, and the rapid emergence of bacterial resistance caused by the abuse of antibiotics exacerbates the seriousness of this problem. Effectively utilizing natural products to construct new antimicrobial strategies is regarded as a promising way to suppress the rapid development of bacterial resistance. In this paper, we fabricated a new type of natural antibacterial patch by using a natural active substance (allicin) as an antibacterial agent and the porous structure of the white pulp of pomelo peel as a scaffold. The antibacterial activity and mechanisms were systematically investigated by using various technologies, including the bacteriostatic circle, plate counting, fluorescence staining, and a scanning electron microscope. Both gram-positive and negative bacteria can be effectively killed by this patch. Moreover, this natural antibacterial patch also showed significant anti-skin infection activity. This study provides a green approach for constructing efficient antibacterial patches.

Screening of multifunctional fruit carbon dots for fluorescent labeling and sensing in living immune cells and zebrafishes.

Nine kinds of carbon dots (CDs) were synthesized by using fruits with different varieties as carbon sources; meanwhile, the fluorescence characteristics, quantum yield, and response ability to different metal ions and free radicals were systematically studied. These CDs showed similar excitation and emission spectral ranges (λex ≈ 345 nm, λem ≈ 435 nm), but very different fluorescence quantum yield (QY), in which orange and cantaloupe CDs have the highest QY around 0.25 and green plum CDs showed the lowest quantum yield around 0.1. Interestingly, the fluorescence of all of these CDs can be significantly quenched by hydroxyl radical (•OH) and iron ion (Fe3+); however, these CDs showed very different response characteristics to other metal ions (e.g., Co2+, Ni2+, Cu2+, Ce3+, Mn2+, Ag+, and Fe2+). Through in-depth analysis, we found some interesting patterns of the influence of carbon sources on the fluorescence characteristics of CDs. Finally, by using white pitaya CDs as fluorescence probe, we realized sensing of Fe3+ and •OH with limits of detection (LOD) of 19.4 µM and 0.7 µM, respectively. Moreover, the CDs were also capable for sensitive detection in immune cells and even in zebrafishes. Our work can provide valuable guidance for the rational design of functional CDs for biological applications.

Will the Bacteria Survive in the CeO2 Nanozyme-H2O2 System?

As one of the nanostructures with enzyme-like activity, nanozymes have recently attracted extensive attention for their biomedical applications, especially for bacterial disinfection treatment. Nanozymes with high peroxidase activity are considered to be excellent candidates for building bacterial disinfection systems (nanozyme-H2O2), in which the nanozyme will promote the generation of ROS to kill bacteria based on the decomposition of H2O2. According to this criterion, a cerium oxide nanoparticle (Nanoceria, CeO2, a classical nanozyme with high peroxidase activity)-based nanozyme-H2O2 system would be very efficient for bacterial disinfection. However, CeO2 is a nanozyme with multiple enzyme-like activities. In addition to high peroxidase activity, CeO2 nanozymes also possess high superoxide dismutase activity and antioxidant activity, which can act as a ROS scavenger. Considering the fact that CeO2 nanozymes have both the activity to promote ROS production and the opposite activity for ROS scavenging, it is worth exploring which activity will play the dominating role in the CeO2-H2O2 system, as well as whether it will protect bacteria or produce an antibacterial effect. In this work, we focused on this discussion to unveil the role of CeO2 in the CeO2-H2O2 system, so that it can provide valuable knowledge for the design of a nanozyme-H2O2-based antibacterial system.

Near-infrared light-heatable platinum nanozyme for synergistic bacterial inhibition.

The development of non-antibiotic strategies for bacterial disinfection is of great clinical importance. Among recently developed different antimicrobial strategies, nanomaterial-mediated approaches, especially the photothermal way and reactive oxygen species (ROS)-generating method, show many significant advantages. Although promising, the clinical application of nanomaterials is still limited, owing to the potential biosafety issues. Further improvement of the antimicrobial activity to reduce the usage, and thus reduce the potential risk, is an important way to increase the clinical applicability of antibacterial nanomaterials. In this paper, an antimicrobial nanostructure with both an excellent photothermal effect and peroxidase-like activity was constructed to achieve efficient synergistic antimicrobial activity. The obtained nano-antimicrobial agent (ZIF-8@PDA@Pt) can not only efficiently catalyze the production of ROS from H2O2 to cause damage to bacteria but also convert the photon energy of near-infrared light into thermal energy to kill bacteria, and the two synergistic effects induced in a highly efficient antimicrobial activity. This study not only offers a new nanomaterial with efficient antibacterial activity but also proposes a new idea for constructing synergistic antibacterial properties.