53 research outputs found
Polymer-Ag Nanocomposites with Enhanced Antimicrobial Activity against Bacterial Infection
Herein, a nontoxic nanocomposite
is synthesized by reduction of
silver nitrate in the presence of a cationic polymer displaying strong
antimicrobial activity against bacterial infection. These nanocomposites
with a large concentration of positive charge promote their adsorption
to bacterial membranes through electrostatic interaction. Moreover,
the synthesized nanocomposites with polyvalent and synergistic antimicrobial
effects can effectively kill both Gram-positive and Gram-negative
bacteria without the emergence of bacterial resistance. Morphological
changes obtained by transmission electron microscope observation show
that these nanocomposites can cause leakage and chaos of intracellular
contents. Analysis of the antimicrobial mechanism confirms that the
lethal action of nanocomposites against the bacteria started with
disruption of the bacterial membrane, subsequent cellular internalization
of the nanoparticles, and inhibition of intracellular enzymatic activity.
This novel antimicrobial material with good cytocompatibility promotes
healing of infected wounds in diabetic rats, and has a promising future
in the treatment of other infectious diseases
Functional Silver Nanoparticle as a Benign Antimicrobial Agent That Eradicates Antibiotic-Resistant Bacteria and Promotes Wound Healing
With the increased prevalence of
antibiotic-resistant bacteria infections, there is a pressed need
for innovative antimicrobial agent. Here, we report a benign ε-polylysine/silver
nanoparticle nanocomposite (EPL-<i>g</i>-butyl@AgNPs) with
polyvalent and synergistic antibacterial effects. EPL-<i>g</i>-butyl@AgNPs exhibited good stability in aqueous solution and effective
antibacterial activity against both Gram-negative (<i>P. aeruginosa</i>) and Gram-positive (<i>S. aureus</i>) bacteria without
emergence of bacterial resistance. Importantly, the nanocomposites
eradicated the antibiotic-resistant bacteria without toxicity to mammalian
cells. Analysis of the antibacterial mechanism confirmed that the
nanocomposites adhered to the bacterial surface, irreversibly disrupted
the membrane structure of the bacteria, subsequently penetrated cells,
and effectively inhibited protein activity, which ultimately led to
bacteria apoptosis. Notably, the nanocomposites modulated the relative
level of CD3<sup>+</sup> T cells and CD68<sup>+</sup> macrophages
and effectively promoted infected wound healing in diabetic rats.
This work improves our understanding of the antibacterial mechanism
of AgNPs-based nanocomposites and offers guidance to activity prediction
and rational design of effective antimicrobial nanoparticles
Functional Silver Nanocomposites as Broad-Spectrum Antimicrobial and Biofilm-Disrupting Agents
Biofilms’ tolerance has become
a serious clinical concern
due to their formidable resistance to conventional antibiotics and
prevalent virulence. Therefore, there is an urgent need to develop
alternative antimicrobial agents to eradicate biofilms but avoid using
antibiotics. Herein, we successfully developed polymer functional
silver nanocomposites by reduction of silver nitrate in the presence
of a biocompatible carbohydrate polymer and a membrane-disrupting
cationic polymer. The nanocomposites presented effective antimicrobial
activity against Gram-negative bacteria (Pseudomonas
aeruginosa, Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus and Bacillus amyloliquefaciens).
Confocal laser scanning macroscopy imaging demonstrated that the nanocomposites
could efficiently disperse and eradicate the mature biofilms formed
by the above four bacterial strains. The introduction of carbohydrate
polymers onto nanocomposites effectively improved the biocompatibility,
and these nanocomposites induced no significant red blood cell hemolysis
and cytotoxicity toward mammalian cells. More importantly, the nanocomposites
were able to well eradicate the bacterial biofilms formed on the silicone
implants in vivo. In conclusion, the nanocomposites as the broad-spectrum
biofilm-disrupting agent are significant in the design of new strategies
to eradicate biofilms on indwelling medical devices
Near-Infrared Light-Activated Thermosensitive Liposomes as Efficient Agents for Photothermal and Antibiotic Synergistic Therapy of Bacterial Biofilm
Biofilm is closely
related to chronic infections and is difficult to eradicate. Development
of effective therapy strategies to control biofilm infection is still
challenging. Aiming at biofilm architecture, we designed and prepared
near-infrared-activated thermosensitive liposomes with photothermal
and antibiotic synergistic therapy capacity to eliminate Pseudomonas aeruginosa biofilm. The liposomes with
positive charge and small size aided to enter the biofilm microchannels
and locally released antibiotics in infection site. The liposomes
could remain stable at 37 °C and release about 80% antibiotics
over 45 °C. The biofilm dispersion rate was up to 80%, which
was a 7- to 8-fold rise compared to excess antibiotic alone, indicating
that the localized antibiotic release and photothermal co-therapy
improved the antimicrobial efficiency. In vivo drug-loaded liposomes
in treating P. aeruginosa-induced abscess
exhibited an outstanding therapeutic effect. Furthermore, photothermal
treatment could stimulate the expression of bcl2-associated athanogene
3 to prevent normal tissue from thermal damage. The near-infrared-activated
nanoparticle carriers had the tremendous therapeutic potential to
dramatically enhance the efficacy of antibiotics through thermos-triggered
drug release and photothermal therapy
A Water-Soluble Galactose-Decorated Cationic Photodynamic Therapy Agent Based on BODIPY to Selectively Eliminate Biofilm
A multitude
of serious chronic infections are involved in bacterial biofilms that
are difficult to eradicate. Here, a water-soluble galactose-functionalized
cationic 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY)-based
photodynamic therapy agent was synthesized for selectively eliminating
the bacterial biofilm. These conjugates can capture bacteria to form
aggregations through electrostatic interaction and then generate a
large number of reactive oxygen species (ROS) under visible light
irradiation to kill the bacteria without the emergence of bacterial
resistance. Simultaneously, this agent could effectively inhibit and
eradicate both Gram-positive and Gram-negative bacterial biofilms.
The in-depth analysis of the antimicrobial mechanism confirmed that
the conjugates can quickly bind on the bacterial surface, irreversibly
disrupt the bacterial membrane, and distinctly inhibit intracellular
enzyme activity, ultimately leading to the bacterial death. Importantly,
these conjugates are highly selective toward bacterial cells over
mammalian cells as well as no cytotoxicity to A549 cells and no discernible
hemolytic activity. Collectively, this water-soluble galactose-decorated
cationic BODIPY-based photodynamic therapy agent design provides promising
insights for the development of therapy for antibiotic-resistant bacteria
Single Continuous Near-Infrared Laser-Triggered Photodynamic and Photothermal Ablation of Antibiotic-Resistant Bacteria Using Effective Targeted Copper Sulfide Nanoclusters
The emergence of
antibiotic-resistant bacterial strains has made conventional antibiotic
therapies less efficient. The development of a novel nanoantibiotic
approach for efficiently ablating such bacterial infections is becoming
crucial. Herein, a collection of polyÂ(5-(2-ethyl acrylate)-4-methylthiazole-<i>g</i>-butyl)/copper sulfide nanoclusters (PATA-C4@CuS) was synthesized
for efficient capture and effective ablation of levofloxacin-resistant
Gram-negative and Gram-positive bacteria upon tissue-penetrable near-infrared
(NIR) laser irradiation. In this work, we took advantage of the excellent
photothermal and photodynamic properties of copper sulfide nanoparticles
(CuSNPs) upon NIR laser irradiation and thiazole derivative as a membrane-targeting
cationic ligand toward bacteria. The conjugated nanoclusters could
anchor the bacteria to trigger the bacterial aggregation quickly and
efficiently kill them. These conjugated nanoclusters could significantly
inhibit levofloxacin-resistant Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Bacillus
amyloliquefaciens at 5.5 ÎĽg/mL under NIR laser
irradiation (980 nm, 1.5 W cm<sup>–2</sup>, 5 min), which suggested
that the heat and reactive oxygen species (ROS) generated from the
irradiated CuSNPs attached to bacteria were effective in eliminating
and preventing the regrowth of the bacteria. Importantly, the conjugated
nanoclusters could promote healing in bacteria-infected rat wounds
without nonspecific damage to normal tissue. These findings highlight
the promise of the highly versatile multifunctional nanoantibiotics
in bacterial infection
An Acid-Triggered Degradable and Fluorescent Nanoscale Drug Delivery System with Enhanced Cytotoxicity to Cancer Cells
To
reduce side-effects of anticancer drugs, development of nanocarriers
with precise biological functions is a critical requirement. In this
study, the multifunctional nanoparticles combining imaging and therapy
for tumor-targeted delivery of hydrophobic anticancer drugs were prepared
via self-assembly of amphiphilic copolymers obtained using RAFT polymerization,
specifically, acid-labile ortho ester and galactose. First, boron-dipyrromethene
dye-conjugated chain transfer agent provides fluorescent imaging capability
for diagnostic application. Second, nanoparticles were stable under
physiological conditions but degraded in acidic tumor microenvironment,
leading to enhanced anticancer efficacy. Third, the application of
biocompatible glycopolymers efficiently increased the target-to-background
ratio through carbohydrate–protein interactions. Data from
cell viability, cellular internalization, flow cytometry, biodistribution
and anticancer efficacy tests showed that the drug-loaded nanoparticles
were capable of inhibiting cancer cell proliferation with significantly
enhanced capacity. Our newly developed multifunctional nanoparticles
may thus facilitate the development of effective drug delivery systems
for application in diagnosis and therapy of cancer
Structure–Activity Relationship of Membrane-Targeting Cationic Ligands on a Silver Nanoparticle Surface in an Antibiotic-Resistant Antibacterial and Antibiofilm Activity Assay
To
explore the structure–activity relationship of membrane-targeting
cationic ligands on a silver nanoparticle surface in an antibiotic-resistant
antibacterial and antibiofilm activity assay, a series of functionalized
silver nanocomposites were synthesized. Tuning the structural configuration,
molecular weight, and side-chain length of the cationic ligands on
the nanoparticle surface provided silver nanocomposites with effective
antibacterial activity against both antibiotic-resistant Gram-negative
and Gram-positive bacteria, including bacterial biofilms. These silver nanocomposites did not trigger hemolytic activity.
Significantly, the bacteria did not develop resistance to the obtained
nanocomposites even after 30 generations. A study of the antibacterial
mechanism confirmed that these nanocomposites could irreversibly disrupt
the membrane structure of bacteria and effectively inhibit intracellular
enzyme activity, ultimately leading to bacterial death. The silver
nanocomposites (64 ÎĽg/mL) could eradicate 80% of an established
antibiotic-resistant bacterial biofilm. The strong structure–activity
relationship toward antibacterial and antibiofilm activity suggests
that variations in the conformational property of the functional ligand
could be valuable in the discovery of new nano-antibacterial agents
for treating pathogenic bacterial infections
Fig 2 -
Kaplan–Meier plot of cumulative incidence of remission of type 2 diabetes (A) and cumulative incidence of return to hyperglycaemia among people with diabetes remission (B) according to 1-year weight change (%) after diabetes diagnosis.</p
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