Six‐Pointed Star Chiral Cobalt Superstructures with Strong Antibacterial Activity

Abstract

Chiral inorganic nanomaterials have shown promise as a potential means of combating bacteria due to their high levels of biocompatibility, easy surface modification, and excellent optical properties. In this study, a diverse range of chiral hierarchical nanomaterials are prepared from Co 2+ and L/D-Tartaric acid (Tar) ligands. By combining the ligands in different ratios, chiral Co superstructures (Co SS) are obtained with different morphologies, including chiral nanoflowers, chiral nanohanamaki, a chiral six-pointed star, a chiral fan shape, and a chiral fusiform shape. It is found that the chiral six-pointed star structures exhibit chiroptical activity across a broad range of wavelengths from 300 to 1300 nm and that the g-factor is as high as 0.033 with superparamagnetic properties. Under the action of electromagnetic fields, the chiral six-pointed star Co SS shows excellent killing ability against Gram-positive Staphylococcus aureus (ATCC 25923). Compared to L-Co SS, D-Co SS shows stronger levels of antibacterial ability. It is found that the levels of reactive oxygen species generated by D-Co SS are 1.59-fold higher than L-Co SS which is attributed to chiral-induced spin selectivity effects. These findings are of significance for the further development of chiral materials with antibacterial properties.

Chiral Magnetic Oxide Nanomaterials: Magnetism Meets Chirality

“…The six‐pointed star nanostructure with helical symmetry exhibited the strongest g‐factor value of 0.033 at 1180 nm. [ 78 ] The weaker chiroptical response of the other twisted supernanostructures was assigned to the nonuniform morphology and lower symmetry.…”

“…Reproduced with permission. [ 78 ] Copyright 2022, Wiley‐VCH. f) SEM images of cross‐section of chiral NiO films.…”

“…Under combined treatment of CMONs and magnetic field, no obvious inflammatory action was revealed, indicating that D‐CMONs can promote the generation of most abundant singlet oxygen to obtain the best antibacterial activity. [ 78 ]…”

“…Reproduced with permission. [78] Copyright 2022, Wiley-VCH. HClO up to a detection limit of 0.933 × 10 −9 m (Figure 9e).…”

Chiral Sulfur Nanosheets for Dual-Selective Inhibition of Gram-Positive Bacteria

“…In the past decades, the rapid evolution of drug-resistant bacteria has become a global challenge due to the abuse of antibiotics. − Particularly, Gram-positive (G+) drug-resistant bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE), have captured much attention. − Presently, MRSA and VRE are two major causes of nosocomial infections, while the available drugs for treating them are limited . Thus, selective inhibition of G+ bacteria is of significance in practice. , Fortunately, compared with the cell wall structure of Gram-negative (G−) bacteria, the G+ bacterial cell walls do not contain an outer membrane composed of lipids, proteins, and lipopolysaccharides, making them more susceptible to antibiotics or other antibacterial agents. − Meanwhile, bacteria prefer to use d -amino acids in the biosynthesis of the peptidoglycan cell wall, while mammalian cells exclusively uptake l -amino acids. − This property reveals the feasibility of d -amino acids for the selective killing of G+ bacteria. − …”