Because
of their antibacterial activity, silver nanoparticles (AgNPs)
have been explored in biomedical applications. Similarly, nitric oxide
(NO) is an important endogenous free radical with an antimicrobial
effect and toxicity toward cancer cells that plays pivotal roles in
several processes. In this work, biogenic AgNPs were prepared using
green tea extract and the principles of green chemistry, and the NO
donor S-nitrosoglutathione (GSNO) was prepared by
the nitrosation of glutathione. To enhance the potentialities of GSNO
and AgNPs in biomedical applications, the NO donor and metallic nanoparticles
were individually or simultaneously incorporated into polymeric solid
films of poly(vinyl alcohol) (PVA) and poly(ethylene glycol) (PEG).
The resulting solid nanocomposites were characterized by several techniques,
and the diffusion profiles of GSNO and AgNPs were investigated. The
results demonstrated the formation of homogeneous PVA/PEG solid films
containing GSNO and nanoscale AgNPs that are distributed in the polymeric
matrix. PVA/PEG films containing AgNPs demonstrated a potent antibacterial
effect against Gram-positive and Gram-negative bacterial strains.
GSNO-containing PVA/PEG films demonstrated toxicity toward human cervical
carcinoma and human prostate cancer cell lines. Interestingly, the
incorporation of AgNPs in PVA/PEG/GSNO films had a superior effect
on the decrease of cell viability of both cancer cell lines, compared
with cells treated with films containing GSNO or AgNPs individually.
To our best knowledge, this is the first report to describe the preparation
of PVA/PEG solid films containing GSNO and/or biogenically synthesized
AgNPs. These polymeric films might find important biomedical applications
as a solid material with antimicrobial and antitumorigenic properties.
Nitric oxide (NO) is involved in physiological processes, including vasodilatation, wound healing and antibacterial activities. As NO is a free radical, designing drugs to generate therapeutic amounts of NO in controlled spatial and time manners is still a challenge. In this study, the NO donor S-nitrosoglutathione (GSNO) was incorporated into the thermoresponsive Pluronic F-127 (PL)-chitosan (CS) hydrogel, with an easy and economically feasible methodology. CS is a polysaccharide with known antimicrobial properties. Scanning electron microscopy, rheology and differential scanning calorimetry techniques were used for hydrogel characterization. The results demonstrated that the hydrogel has a smooth surface, thermoresponsive behavior and good mechanical stability. The kinetics of NO release and GSNO diffusion from GSNO-containing PL/CS hydrogel demonstrated a sustained NO/GSNO release, in concentrations suitable for biomedical applications. The GSNO-PL/CS hydrogel demonstrated a concentration-dependent toxicity to Vero cells, and antimicrobial activity to Pseudomonas aeruginosa (minimum inhibitory concentration and minimum bactericidal concentration values of 0.5 µg·mL−1 of hydrogel, which corresponds to 1 mmol·L−1 of GSNO). Interestingly, the concentration range in which the NO-releasing hydrogel demonstrated an antibacterial effect was not found to be toxic to the Vero mammalian cell. Thus, the GSNO-PL/CS hydrogel is a suitable biomaterial for topical NO delivery applications.
Nitric
oxide (NO) and silver nanoparticles (AgNPs) are well-known
for their antibacterial activity. In this work, S-nitroso-mercaptosuccinic
acid (S-nitroso-MSA), a NO donor, and green tea synthesized AgNPs
were individually or simultaneously incorporated into alginate hydrogel
for topical antibacterial applications. The obtained hydrogels were
characterized and the NO release and diffusion of AgNPs and S-nitroso-MSA
from alginate hydrogels were investigated. The hydrogels showed a
concentration dependent toxicity toward Vero cells. The potent antibacterial
effect of the hydrogels was demonstrated toward Escherichia
coli ATCC 25922, Staphylococcus aureus ATCC
25923, and Streptococcus mutans UA159. Interestingly,
the combination of S-nitroso-MSA and AgNPs into alginate hydrogels
had a superior antibacterial effect, compared with hydrogels containing
S-nitroso-MSA or AgNPs individually. This is the first report to describe
the synthesis, cytotoxicity, and antibacterial effects of alginate
hydrogel containing NO donor and AgNPs. These hydrogels might find
important local applications in the combat of bacterial infections.
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