Copper-containing
antimicrobials are highly valuable in the field
of medical disinfectants owing to their well-known high antimicrobial
efficacy. Artificially synthesized nanozymes which can increase the
level of reactive oxygen species (ROS) in the bacterial system have
become research hotspots. Herein, we describe the design and fabrication
of degradable Cu-doped phosphate-based glass (Cu-PBG) nanozyme, which
can achieve excellent antibacterial effects against Gram-positive
and Gram-negative bacteria. The antibacterial mechanism is based on
the generation of ROS storm and the release of copper. It behaves
like a peroxidase in wounds which are acidic and exerts lethal oxidative
stress on bacteria via catalyzing the decomposition
of H2O2 into hydroxyl radicals (•OH). Quite different from any other reported nanozymes, the Cu-PBG
is intrinsically degradable due to its phosphate glass nature. It
gradually degrades and releases copper ions in a physiological environment,
which further enhances the inhibition efficiency. Satisfactory antibacterial
effects are verified both in vitro and in
vivo. Being biodegradable, the prepared Cu-PBG exhibits excellent in vivo biocompatibility and does not cause any adverse
effects caused by its long-time residence time in living organisms.
Collectively, these results indicate that the Cu-PBG nanozyme could
be used as an efficient copper-containing antimicrobial with great
potential for clinical translation.
The major challenge in the field of antibacterial agents is to overcome the low-permeability of bacteria cell membranes that protects the cells against diverse drugs. In this work, water-soluble polyaniline (PANI)-poly (p-styrenesulfonic acid) (PSS) (PANI:PSS) is found to spontaneously penetrate bacteria cellular membranes in a non-disruptive way, leaving no evidence of membrane poration/disturbance or cell death, thus avoiding side effects caused by cationic ammonia groups in traditional ammonia-containing antibacterial agents. For aqueous synthesis, which is important for biocompatibility, the polymer is synthesized via an enzyme-mimetic route relying on the catalysis of a nanozyme. Owing to its fluorescent properties, the localization of as-prepared PANI:PSS is determined by the confocal microscope, and the results confirm its rapid entry into bacteria. Under 808 nm near-infrared (NIR) irradiation, the internalized PANI:PSS generates local hyperthermia and destroys bacteria highly efficiently from inside the cells due to its excellent photothermal effects.
Staphylococcus aureus
(
S. aureus
),
M
ethicillin-resistant
Staphylococcus aureus
(
MRSA
) and
Escherichia coli
(
E. coli
) could be effectively eliminated as well as the corresponding bacterial biofilms. Results of
in vivo
antibacterial experiments demonstrate excellent antibacterial activities of the water-soluble PANI:PSS without side effects. Therefore, the prepared water-soluble polymer in this study has great potential in the treatment of various bacterial infections.
Cuprous oxide (Cu2O) nanocubes were synthesized by reducing Cu(OH)2 in the presence of sodium citrate at room temperature. The samples were characterized in detail by field-emission scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, X-ray powder diffraction, and N2 absorption (BET specific surface area). The equations for acquiring reaction kinetic parameters and surface thermodynamic properties of Cu2O nanocubes were deduced by establishment of the relations between thermodynamic functions of Cu2O nanocubes and these of the bulk Cu2O. Combined with thermochemical cycle, transition state theory, basic theory of chemical thermodynamics, and in situ microcalorimetry, reaction kinetic parameters, specific surface enthalpy, specific surface Gibbs free energy, and specific surface entropy of Cu2O nanocubes were successfully determined. We also introduced a universal route for gaining reaction kinetic parameters and surface thermodynamic properties of nanomaterials.
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