Reducing wound bioburden and biofilm formation using a nanoscale wound surface en

描述（由申请人提供）：慢性伤口的管理是一项重大的医疗保健挑战，每年的费用超过150亿美元。创面败血症，特别是生物膜的形成，是造成伤口不愈合的重要因素。在慢性伤口中，60%的伤口有明显的生物膜。此外，美国国立卫生研究院估计，65-80%的人类微生物感染是由生物膜介导的。生物膜的特点是抵抗宿主防御和治疗，否则会对生物体的浮游状态有效。因此，生物膜面临两个截然不同的挑战：1)必须去除或分散生物膜以减少细菌的防御机制；2)使用有效的抗菌药物抑制常驻细菌。在这个应用中，我们试图通过研究一种新的干预措施来解决这个问题，这种干预措施有可能防止伤口的慢性定植和分散预先存在的生物膜。我们方法背后的创新围绕着伤口床表面的工程设计，既促进生物膜细菌的溶解回到浮游状态，在那里它们对抗菌剂更敏感，又将抗菌剂固定在生物膜形成的伤口表面。我们的方法包括在纳米级薄膜中加入可吸收的纳米球，该薄膜由含有银纳米粒子的聚电解质多层制成，用于重新设计伤口表面，以增加其对微生物定植和生物膜形成的抵抗力。这种结构化的工程方法允许有效的抗菌作用与非常低的无毒浓度的活性剂。这些方法在单一纳米结构薄膜中的创新组合有可能显着增加体内的抗生物膜和抗菌功效。特别是纳米珠的使用

DESCRIPTION (provided by applicant): Management of chronic wounds represent a major healthcare challenge responsible for over $15 billion in expenses annually. Wound surface sepsis, in particular biofilm formation, is a significant factor in nonhealing wounds. In chronic wounds, >60% have been observed to have clear evidence of a biofilm. Further, NIH has estimated that 65-80% of microbial infections in humans are biofilm-mediated. Biofilms are characterized by resistance to host defenses and to therapeutics that would otherwise have efficacy against the organisms planktonic state. Thus, biofilms present two distinct challenges: 1) the biofilm must be removed or dispersed to reduce bacterial defense mechanisms; and 2) effective antimicrobial agents applied to suppress the resident bacteria. In this application, we seek to address this problem by investigating a novel intervention with potential to prevent chronic colonization of wounds and disperse pre-existing biofilms. The innovation underlying our approach revolves around engineering the surfaces of wound beds to both promote the dissolution of biofilm bacteria back to a planktonic state, where they are more susceptible to antimicrobial agents, and immobilize antimicrobial agents at the wound surface where biofilm formation occurs. Our approach involves incorporation of absorbable nanobeads loaded with antibiofilm agents in a nanoscopic thin film, manufactured of polyelectrolyte multilayers containing silver nanoparticles, that is used to re-engineer the wound surface to increase its resistance to microbial colonization and biofilm formation. This structured engineered approach allows effective antimicrobial action with very low non-toxic concentrations of active agents. The innovative combination of these approaches in a single nanostructured film has the potential to markedly increase anti-biofilm and antimicrobial efficacy in vivo. In particular, use of nano-beads permits precise control over concentrations and release rates of the antibiofilm agent. They also penetrate and create microdomains within the biofilm, increasing surface contact by >80%, to increase adsorption of antibiofilm and antimicrobial agents concurrently and generating progressive dispersion-kill zones emanating from the beads at a nanoscale level. The central hypothesis of this study, supported by exciting preliminary data, is that incorporating select D- and L- amino acids into the wound bed will reduce bacterial biofilm formation and increase biofilm dissolution. A secondary hypothesis is that this approach will enhance the antimicrobial activity of silver nanoparticles immobilized at the wound surface. To address these goals we propose 3 Aims. In Aim 1, we will evaluate the ability of select D- and L- amino acids immobilized in polyelectrolyte thin films and loaded into absorbable PLGA beads to prevent a biofilm from forming and to stimulate dissolution of existing biofilms of Pseudomonas aeruginosa and Staphylococcus aureus in vitro . In Aim 2, we will optimize the integration of select amino acids and nano-beads onto model wound surfaces (full and partial thickness skin wounds), using polyelectrolyte thin film immobilization methods, and evaluate their efficacy in preventing biofilm formation and biofilm dissolution in vivo; and in Aim 3, we will test the hypothesis that combined application of silver nanoparticles and select amino acids further reduces biofilm formation and minimizes microbial bioburden in wounds in vivo. At the conclusion of this study, we expect to provide proof of concept that a two-armed approach to wound biofilms contained in an integrated nanoscale wound bed engineering platform will have increased efficacy against biofilms with reduced cytotoxicity in the wound bed. This approach is labile and generalizable to immobilization of other antibiofilm and antimicrobial agents. Thus, upon successful completion of this R21 application, we will seek support for research (via the R01 mechanism) that will broaden the scope of these investigations in optimizing these strategies and in evaluating the efficacy of an array of antimicrobial and antibiofilm agents with the goal of maximizing the ability to suppress wound bed sepsis and improve healing of chronic open wounds.