薄如蝉翼—超薄纳米银辅料

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薄如蝉翼—超薄纳米银辅料

2016-12-09 SIFIC官微 信息与电子前沿

本文转载自微信公众号：SIFIC官微

薄如蝉翼—超薄纳米银辅料

检索、翻译：王珍丽

编写：陈志锦

审核：陈松婷、陈志锦

（SIFIC热点团队）

纳米银辅料通过纳米银和载体材料良好的结合使辅料与伤口接触后能持续地释放出具有抗菌性能的银离子，达到理想的抗菌效果。纳米银敷料在临床上的应用经临床观察发现纳米银有显著抗菌及促进创面愈合的疗效，控制感染效果明显，己广泛地应用于烧烫伤外科、多种疾病引起的皮肤溃疡，特别是用于对久治不愈的褥疮或其他慢性感染创面。

研究结果显示，对耐甲氧西林金黄色葡萄球菌（MRSA）和耐万古霉素肠球菌等危害性较大的医院获得性超级细菌，纳米银抗菌敷料具有较高的杀菌率。近日，轻薄纳米银抗菌辅料——Microlyte敷料已获得美国食品药物管理局(FDA)颁发的创面敷料许可证，允许其应用于人体。

Microlyte敷料如蝉翼般轻薄，克服了现有敷料的一个重大弱点——硬度，从而能提供更好的覆盖性能。就算在低倍显微镜下,也能轻易观察到，凹凸不平的创面的缝隙俨然成了滋生细菌的温床，只有良好覆盖性的辅料才能充分发挥杀菌作用。

与目前用来治疗烧伤和其他经久未愈的伤口敷料一样，Microlyte 银辅料同样含有可杀死细菌的纳米银成分，但含量却要少很多，仅为竞争产品的1%。这是由于Microlyte敷料具有在潮湿表面易于渗入其缝隙的特性，所以能够在更低的银离子含量的情况下，杀菌效果仍能够得到FDA的测试通过，Microlyte能杀死99.99%以上与之接触的细菌。更少的银离子对正常皮肤细胞的毒性作用更为柔和。

Microlyte的银离子呈缓慢释放状态，杀菌效应至少可持续一天，能够减少辅料更换的次数。且其原材料为水基凝胶，因此具有易撕性，在更换敷料时不会产生疼痛感。在降低耗材成本的同时，也能缓解医务人员的工作压力。

原文

UM-Madison Spinoff Gets FDA OK for Bacteria-Killing Wound Dressing

Imbed's Microlyte dressing is applied to a wound on a pig. The ultra-thin dressing conforms to the wound, bringing the antimicrobial silver into direct contact with bacteria. Courtesy of Imbed Biosciences.

Imbed Biosciences announces it has received clearance from the Food and Drug Administration (FDA) to market its patented wound dressing for human use. The dressing it calls Microlyte Ag is a sheet as thin as Saran Wrap and can conform to the bumps and crevices of a wound, says company CEO Ankit Agarwal.

The dressing is now cleared by the FDA as a class II medical device, for prescription and over-the-counter use.

Like many dressings now used to treat burns and other persistent wounds, Microlyte Ag contains silver to kill bacteria – but in much smaller quantities.

"Silver is an excellent antimicrobial agent," says Agarwal, a co-founder of the company in the Madison suburb of Fitchburg, "as it is active against a broad range of bacteria and yeast. But the large silver loads found in conventional silver dressings can be toxic to skin cells. Our dressing uses as little as 1 percent as much silver as the competition, and yet the tests we submitted to the FDA showed that Microlyte kills more than 99.99 percent of bacteria that it contacts."

That kill ratio even appeared in tests against some of the nastiest hospital-acquired superbugs, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococcus.

Microlyte overcomes a key problem with existing dressings: stiffness. Under a low-power microscope, a wound has bumps and fissures — hiding places for bacteria. The Microlyte dressing inherently adheres to moist surfaces and is so flexible that it drops into the fissures, leading to the sweet combination of greater destruction of bacteria at much lower doses of silver.

Microlyte has several other advantages, Agarwal says. It retains moisture yet is ultrathin and breathable, allowing oxygen to reach the wound and gases to exit, all factors that promote healing. The slow release of the silver means the dressing can remain in place for at least one day. And because the material is a hydrogel (a water-based gel), it can simply be rinsed off as needed before replacement.

Experience with animals shows that the ultra-thin dressing simply sloughs off as the wound heals. All of these advantages should reduce the need to change dressings, which can be so painful that sedation is needed, especially for children.

“Reducing or eliminating dressing changes reduces the pain that the patient experiences,” says co-founder Michael Schurr, chair of general surgery at the Mountain Area Health Education Center in Asheville, N.C., and adjunct professor of surgery at the University of North Carolina. “It also reduces costs in supplies and reduces the burden to the health care system that supplies visiting nurses to do the dressing changes.”

"We are seeing in a limited number of cases that it does provide us with a remarkable new tool for dealing with chronic wounds" in dogs and cats treated at the UW-Madison School of Veterinary Medicine, says Jonathan McAnulty, chair of the Department of Surgical Sciences. "We certainly have no reason to think that this will be different with humans,” adds McAnulty, who is also a company co-founder. “The principles are the same, and a lot of the problems are the same."

The dramatic closure of wounds that have resisted months of conventional treatment "suggests that chronic bacterial contamination of the wound surface, even when it looks relatively healthy, is a significant factor inhibiting healing in many cases," McAnulty says. "Once we treat with our dressing, we start to see very dramatic closure of these wounds."

McAnulty says he’s starting to use Microlyte earlier in treatment. "Certainly it seems appropriate for prevention of infection as well as treatment."

MThe ultra-thin dressing material was invented in the lab of Nicholas Abbott, a UW–Madison professor of chemical and biological engineering, when Agarwal was a postdoctoral fellow and where he is now an honorary associate scientist.

The dressing will compete in the $2 billion market sector of "advanced wound dressings," which are used to treat diabetic ulcers, venous ulcers, burns, bedsores and other difficult wounds.

Imbed has 10 employees. The company is developing other ideas for wound treatment and discussing commercial-scale production of Microlyte. Currently, it plans to reach the market through licensing agreements with hospital suppliers.

Source: University of Wisconsin-Madison

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