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In recent decades, nanoparticles (NPs) have been
investigated for various biomedical applications and they have been
reported to be the ”material of the 21st century” because of their
unique designs and property combinations compared with conventional materials 1 – 2. There is a wide range of applications of
NPs such as in human health appliances, industrial fields, medical
applications, biomedical fields, engineering, electronics, and environmental
studies 1 -7.

Basically, many benefits when using nanoparticles offers
are proved over other drug delivery systems 2. Several advantages of them
could be told as enhancing the solubility of highly hydrophobic drugs;
providing sustained and controlled release of encapsulated drugs; intensifying
the stability of therapeutic agents by chemical or physical means; targeted
treatments when modified with cell-specific ligands 2. Among all of the nanomaterials, variety of metallic
nanoparticles have considered as the foremost attention due to their useful
application to various fieldss of science and technology 1 – 7. The most
widely used delegate of metallic NPs is silver
nanoparticles (AgNPs) because of their highly effective
antibacterial activity both in solution and in components, AgNPs have gained
popularity in industrial sectors including textiles, food, consumer products,
medicine. 3 – 12

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AgNPs (ranging in size from ~1 -100 nm) can be prepared
with many methods: (i) chemical synthesis, (ii) physical dispersion, (iii)
photochemical synthesis, and (iv) biological synthesis 9. Lately, Zhang et
al. has reported on three multistep methods used to prepare silver
nanostructures with well-controlled shapes: (i) double reductant method, (ii)
etching technique, and (iii) construction of core-shell nanostructures. These
nanoparticles had excellent optical properties 10. Hiep et al. has studied
that using microwave-assisted synthesis of chitosan/polyvinyl alcohol/AgNPs
gels matrix without using any reducer make AgNPs exhibited a spherical shape sizes
oranged from 3 to 19 nm and those gels have good biocompatibility and safety to
be used for wound
applications 5.

However, the use
of AgNPs carries a series of unpredictable concerns regarding their interaction
with biological systems 13 – 14. Several studied has suspected the negative
effects of the strong oxidative activity of AgNPs releasing silver ions with biological
systems by inducing cytotoxicity, genotoxicity, immunological responses, and
even cell death 15 – 18. Therefore, the profuse applications of AgNPs raise
concerns about human exposure, because they can easily pass through the blood
brain barrier by transcytosis of capillary endothelial cells or into other
critical areas or tissues 19.

Obviously, human
became at risks induced by exposure to nanoparticles (NPs; diameter < 100 nm) either from ambient air or therapeutic uses as drug delivery. 20. According to Aueviriyavit et al., Ag products in colloidal form for medicinal or other purposes have activated Ag+, which might have a direct effect on human health 22.. Moreover, it is hypothesized that Ag+ possesses an enhanced toxicity potential than elemental Ag and AgNPs 18. The interaction processes of nanomaterials with biological systems are unknown and consequently might be of great concern 14, 24. The toxicity of other NPs in different organisms has been reported in various studies whereas the toxicity of AgNPs has not been extensively explored. For example, titanium dioxide (TiO2) NPs induce reactive oxygen species (ROS), which further initiate lipid peroxidation, protein dysfunction, and DNA degradation, finally triggering oxidative damage in the mouse brain 24. Little is known about the diversified mechanisms of action of the cytotoxicity of Ag-NPs, as well as their short- or long-term exposure outcomes, on human physiology 25, 26.. Therefore, the toxicological studies on AgNPs have become a raising topic over the past few decades due to their unique properties on the nanoscale and widespread in many commercial products that launched into the market recently 21. Besides, the silver nanoparticles show efficient antimicrobial property compared to other salts due to their extremely large surface area, which provides better contact with microorganisms. In this era, as antibiotic resistance continues to emerge, alternatives need to be sought for the topical treatment of skin disorders and topical silver products are widely promoted in the wound care arena. Nanocrystalline technology improves the delivery of silver to a wound 34. The nanoparticles get attached to the cell membrane and also penetrate inside the bacteria. The bacterial membrane contains sulfur-containing proteins and the silver nanoparticles interact with these proteins in the cell as well as with the phosphorus containing compounds like DNA. When silver nanoparticles enter the bacterial cell it forms a low molecular weight region in the center of the bacteria to which the bacteria conglomerates thus, protecting the DNA from the silver ions. The nanoparticles preferably attack the respiratory chain, cell division finally leading to cell death. The nanoparticles release silver ions in the bacterial cells, which enhance their bactericidal activity 27, 28. To control the release rate of silver ion from AgNPs and increase antimicrobial effect, several researches have suggested composed AgNPs with other biocompatible polymers such as chitosan, polyvinyl alcohol, poly (vinyl alcohol), poly (vinyl pyrolidone), poly (lactic acid), etc. to create wound healing application in the type of topical hydrogels, dressing, mats 29 – 32. For example, Zhou et al. created the matrix of gelatin/carboxymethyl chitosan loading silver nanopartcles. The results shows that this matrix has good physical properties and long-time antibacterial activity 33. The study of Gaarfa et al. showed that AgNPs used singly or combined with CS NPs are promising drugs to eliminate the parasite 34. However, the poor physical property and limited antibacterial activity of CS require a combination between this natural polymer and other synthesized polymer to cover those drawbacks 35, 36. Among those biological polymers, CS and PVA appear as the salient in the hydrogels loading AgNPs since chitosan is a unique biopolymer that exhibits outstanding properties, beside biocompatibility and biodegradability 37, 38. Recent studies showed that one promised alternative to enhance the benefits of chitosan properties is to blend chitosan with another water soluble polymer such as poly (vinyl alcohol) (PVA) 5, 29, 30, 39. Due to their highly resistance to oil, grease and solvents, high chemical stability excellent oxygen and aroma barrier properties, PVA presentd itself as a factor in wound healing dressing to create a covered membrane absorbing water, helping CS and AgNPs easily to access and kill bacteria. In Vietnam, recently, medical products using the technology of silver nanoparticles have been developed. In 2015, Anh et al. studied the  Synthesis and characterization of gold – silver alloy nanoparticles for medical purposes 46. In 2016, Hiep et al. was public a research about Microwave-Assisted Synthesis of Chitosan/Polyvinyl Alcohol Silver Nanoparticles Gel for Wound Dressing Applications 5. Although those studies have suggested several methods to fabricate and synthesis wound dressing loading AgNPs, deeper investigations need conducted to create optimized medical products for consumer.

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