SGER: Exploratory studies of atmospheric-pressure glow plasma processing of bio-degradable polymer microparticles

公共摘要CTS-0511817SGER：大气压辉光等离子体处理生物可降解聚合物微粒的探索性研究PI：Laxminarayan L Raja和Krishnendu Roy研究所：德克萨斯大学奥斯汀分校大气压辉光放电的发现为基于等离子体的材料处理技术开辟了前景广阔的新途径。APG放电具有与经典低压辉光放电相似的非平衡热和化学性质，尽管是在单大气压和室温条件下。因此，在不需要昂贵的真空设备的情况下，可以连续加工精细/软材料、颗粒材料，甚至液体形式的材料。我们最近提出了这些放电在可生物降解聚合物微粒加工中的一种新应用。这些聚合物微粒被用作药物/疫苗进入人体的载体。在处理这些携带药物的颗粒的过程中，一个重要的步骤是在它们的表面带上负电荷来激活它们。目前，这是通过湿化学过程实现的，这些过程效率低、重复性差，并产生不受欢迎的液体废物副产品。一种基于APG等离子体的干燥、高效和高通量的生物可降解聚合物微粒表面功能化工艺可以解决湿化学加工方法的许多问题。在这里，我们建议论证利用APG放电对聚合物微粒进行阴离子表面活化的可行性。这项探索性研究将包括以下活动：1)我们将开发一种灵活的、高通量的基于APG等离子体的生物聚合物微粒加工技术。2)使用含有氦工作气体和氧气添加剂的反应性APG等离子体来演示微粒的负电荷激活潜力。3)将通过使用大量的等离子体诊断和材料表征技术来探索APG等离子体-粒子处理技术的几个详细方面。等离子体诊断包括通过测量放电电压-电流波形、光学成像和光学发射光谱来进行电学表征。材料表征将通过测量颗粒Zeta电位、扫描电子显微镜成像和用于颗粒表面元素分析的X射线光电子能谱来执行。预计将有两个重要的技术影响领域：1)APG等离子体放电技术将通过实现这一相对较新的放电类别的重要材料处理应用而受到影响。虽然已经提出了许多应用，从材料的沉积/刻蚀到等离子体流动控制，但APG放电技术还没有在行业中得到成功和广泛的应用。2)将关键的“湿化学”工艺步骤替换为环境友好的“干”等离子体工艺，将影响现有的生物聚合物药物输送微粒的制造技术。我们希望，这一过程的成功演示将成为进一步研究基于等离子体的生物材料制造干法替代技术的动力(该领域目前以湿法加工为主)。我们预计，这项探索性研究将成为对APG等离子体-生物聚合物加工技术的独特方面进行更系统、更长期的基础研究的先导。

Public AbstractCTS-0511817SGER: Exploratory studies of atmospheric-pressure glow plasma processing of bio-degradable polymer microparticlesPIs: Laxminarayan L Raja and Krishnendu RoyInstitution: University of Texas at AustinDiscovery of atmospheric-pressure glow (APG) discharges have created promising new avenues for plasma-based materials processing technologies. APG discharges have non-equilibrium thermal and chemical properties similar to classical low-pressure glow discharges, albeit under one-atmosphere and room-temperature conditions. Consequently, continuous processing of delicate/soft materials, particulate materials, and even materials in the liquid form are possible without need for expensive vacuum equipment. We have recently proposed a novel application of these discharges in the processing of biodegradable polymer microparticles. These polymer microparticles are used as vehicles for drug/vaccine delivery into the human body. An important step in the processing of these drug-laden particles is to activate them with a negative charge on their surface. Currently, this is achieved through a wet chemical processes that are inefficient, poorly reproducible, and engender undesirable liquid waste by-products. An APG plasma-based dry, efficient, and high-throughput process for the surface functionalization of bio-degradable polymer microparticles can address many of the problems with the wet-chemical processing approach. Here we propose to demonstrate the feasibility of using APG discharges for anionic surface activation of polymer microparticles. This exploratory research will comprise the following activities: 1) we will develop a flexible, high-throughput APG plasma-based technique for the processing of biopolymer microparticles. 2) Reactive APG plasmas involving helium working gas and oxygen additives will be used to demonstrate the potential for negative charge activation of the microparticles. 3) Several detailed aspects of the APG plasma-particle processing technique will be explored by employing a host of plasma diagnostic and materials characterization techniques. Plasma diagnostics include electrical characterization by measuring discharge voltage-current waveforms, optical imaging, and optical emission spectroscopy. Materials characterization will be performed by measuring particle zeta potentials, scanning electron microscopy imaging, and X-ray photoelectron spectroscopy for particle surface elemental analysis. Two important areas of technical impact are envisioned: 1) APG plasma discharge technology will be impacted through realization of an important material processing application for this relatively new class of discharges. Although numerous applications have been proposed ranging from the deposition/etching of materials to plasma flow control, APG discharge technology is yet to witness a successful and widespread application in the industry. 2) The existing technology for the manufacture of biopolymer drug-delivery microparticles will be impacted by the replacement of a crucial "wet chemistry-based" process step with an environmentally benign "dry" plasma-based process. We hope that successful demonstration of this process will serve as a motivation for additional research into plasma-based dry replacement technologies for biomaterials manufacture (a field that is currently dominated by wet processing approaches). We anticipate that this exploratory research will serve as precursor to a more systematic, long-term fundamental study of the unique aspects of the APG plasma-biopolymer processing technique.