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Posted: Nov 28, 2006

Applying nanotechnology to better heal wounds

(Nanowerk Spotlight) Wound healing is a complex process and has been the subject of intense research for a long time. Wound healing proceeds through an overlapping pattern of events including coagulation, inflammation, proliferation, and matrix and tissue remodeling. The holy grail for wound healing is accelerated healing without scars. Silver has been used for centuries to prevent and treat a variety of diseases. Its antibacterial effect may be due to blockage of the respiratory enzyme pathways and alteration of microbial DNA and the cell wall. In addition to its recognized antibacterial properties, some authors have reported on the possible pro-healing properties of silver. The use of silver in the past has been restrained by the need to produce silver as a compound, thereby increasing the potential side effects. Nanotechnology has provided a way of producing pure silver nanoparticles and this has provided a new therapeutic modality for use in burn wounds. Nonetheless, the beneficial effects of silver nanoparticles on wound healing remain unknown. A new study reports that silver nanoparticles can promote wound healing and reduce scar appearance.
"We investigated the wound-healing properties of silver nanoparticles in an animal model and found that rapid healing and improved cosmetic appearance occur in a dose-dependent manner" Dr. Kenneth Wong, Clinical Assistant Professor in the Department of Surgery at the University of Hong Kong, explains the recent study to Nanowerk. "We showed that silver nanoparticles exert positive effects besides antibacterial properties: the addition of silver modulates the cytokines involved in wound healing; the degree of inflammation is reduced by silver; and the rate of wound healing is increased with silver"
A paper on these findings, titled "Topical Delivery of Silver Nanoparticles Promotes Wound Healing", that was published in the October 31, 2006 online edition of ChemMedChem.
Immunohistochemical staining for neutrophils with naphthol AS-D chloroacetate esterase; comparison between ND (silver nanoparticles), SSD (sulfadiazine), and no-treatment groups on day 7 after burn injury. Positive staining for neutrophils are denoted by pink spots. (Reprinted with permission from Wiley)
While silver has been used for centuries to prevent and treat a variety of diseases, there has been little scientific data to support that silver actually works. Previous medical research using silver has been conducted with silver compounds thereby increasing the chances for side effects. Wong and his colleagues used pure silver nanoparticles averaging 15 nm, thereby now providing evidence at the molecular level.
But the use of nanosilver, besides being able to test its effects in pure form, has one more advantage: due to the large surface area for reaction of the nanoparticles, the dose of silver used in medical applications can be reduced.
Probably the most important finding of this study is the demonstration that silver nanoparticles act by decreasing inflammation through cytokine modulation. It has been suggested that inflammation actually has a detrimental effect on the wound healing process. If silver nanoparticles contribute to the overall decrease in the inflammatory response and as a consequence, an increased rate of wound healing, the potential benefits of nanosilver in all wounds could be significant.
"The clinical potential of nanosilver can be enormous" says Wong. "It could be applied to all kinds of wounds, including burns, surgical wounds etc. If an average wound heals faster by only one day with silver, a saving of hospital cost would be around USD 150/patient."
Continuing their work with nanosilver, Wong and colleagues now are trying to investigate the actual intracellular molecules that silver binds to and interacts with. "We are also going to explore the effects of silver in other disease models" says Wong. 
By , Copyright Nanowerk LLC

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