Optimized magnetic nanoparticle labels for ultra-sensitive sepsis diagnostics

描述（由申请人提供）：MagneSensors的计划旨在开发专为超灵敏磁性测定量身定制的下一代磁性纳米颗粒标签。这些磁性纳米颗粒将用于检测导致败血症的细菌，其中强烈需要灵敏，特异和快速的可靠诊断测试。该项目利用了一个创新的磁性检测平台，其中磁性纳米颗粒附着在抗体上，抗体以高特异性与靶细菌的表面抗原结合。一个极其敏感的磁传感器，由专利高温超导量子干涉仪（SQUID）组成，定量测量与细菌结合的磁性标签的数量，从而测量样品中的细菌数量。这些优化的磁性纳米颗粒将使用简单的混合和测量格式实现全血中的高灵敏度检测，这是竞争方法所无法实现的。此外，测试可以自动化以实现高通量和低成本。主要强调高灵敏度，以便能够在尽可能早的阶段诊断病原体。虽然最初的重点是检测E。coli O 157：H7，该平台适用于多种细菌。败血症是美国第十大死亡原因，也是非冠状动脉重症监护病房患者的第二大死亡原因。现有的诊断测试是不充分的，并且由于健康护理问题是显著的，因此存在可用于上级测试的大的市场机会。请注意，虽然竞争性扩增核酸检测可以达到必要的灵敏度，但在临床标本上实现它存在许多挑战。缺点包括由于污染导致的假阳性以及较长的周转时间和其他问题，这些问题阻碍了其在临床诊断危及生命的感染方面的可靠使用。第一阶段的目标是：1）合成具有超过50倍大的信号（与目前使用的磁性纳米颗粒相比）并且在血液中稳定的磁性纳米颗粒标记，以及2）证明在45分钟内对250 CFU/ml的细菌的灵敏检测，混合并测量全血中的测定。在第二阶段，灵敏度将进一步提高到<50 CFU/ml，总测定时间仅为15-20分钟，并包括其他相关生物体，如沙门氏菌。金黄色葡萄球菌沿着临床样品的测试。具有较大磁信号的磁性纳米颗粒将通过增加磁芯的总体积以及包括磁芯的磁铁矿晶体的尺寸来合成。最小的聚集和非特异性结合对于全血中的稳定性至关重要，这对于强大的磁性纳米颗粒来说必然更加困难，因为它们具有更大的吸引力。为了实现这种稳定性，我们将使用我们已经开发并在先前工作中成功采用的方法来修改纳米颗粒表面。 公共卫生相关性：脓毒症是美国第十大死亡原因，非冠心病重症监护室患者的第二大死因，每年花费卫生保健系统超过170亿美元。随之而来的抗生素的过度使用进一步导致了细菌的耐药性菌株，显著增加了医院获得性感染，特别是术后伤口，创伤和尿路感染引起败血症的风险。拟议的努力最终集中在对导致败血症的细菌进行快速，超灵敏的诊断测试，使病原体能够在尽可能早的阶段被识别，以便及时使用正确的抗生素进行治疗。

DESCRIPTION (provided by applicant): MagneSensors' program is aimed at developing next generation magnetic nanoparticle labels tailored specifically for ultra-sensitive magnetic assays. These magnetic nanoparticles will be used to detect bacteria leading to sepsis, where there is a strong need for reliable diagnostic tests that are sensitive, specific, and fast. The project takes advantage of an innovative magnetic detection platform where magnetic nanoparticles are attached to antibodies that bind with high specificity to surface antigens on target bacteria. An extremely sensitive magnetic sensor, consisting of a patented high temperature superconducting quantum interference device (SQUID), quantitatively measures the number of magnetic labels bound to the bacteria, and hence the number of bacteria in a sample. These optimized magnetic nanoparticles will enable high sensitivity detection in whole blood using a simple mix and measure format, which is not possible with competing methods. Moreover, the tests can be automated for high throughput and low cost. There is a major emphasis on high sensitivity to enable diagnosis of the pathogen at the earliest possible stage. While the initial focus is on a "proof-of-concept" for the detection of E. coli O157:H7, the platform is applicable to a wide range of bacteria. Sepsis is the tenth-leading cause of death in the U.S. and the second-leading cause of death in non- coronary intensive care unit patients. Existing diagnostic tests are inadequate and there is a large market opportunity available for superior tests, as the health care problem is significant. Note that while competing amplified nucleic acid tests can achieve the necessary sensitivity, there are many challenges to achieving it on clinical specimens. Drawbacks include false positives due to contamination as well as longer turnaround times and other issues that hamper its reliable use for the clinical diagnosis of life threatening infections. The Phase I aims are: 1) to synthesize magnetic nanoparticle labels that have over 50X larger signal (compared to currently used magnetic nanoparticles) and which are stable in blood, and 2) demonstrate sensitive detection of bacteria to 250 CFU/ml in a 45-minute, mix and measure assay in whole blood. In Phase II the sensitivity will be improved further to <50 CFU/ml in as little as 15-20 minutes total assay time, and include additional relevant organisms such as S. aureus along with testing on clinical samples. Magnetic nanoparticles with a larger magnetic signal will be synthesized by increasing the overall volume of the magnetic core as well as the size of the magnetite crystals comprising the core. Minimal aggregation and non-specific binding are critical for stability in whole blood, which is necessarily more difficult for powerful magnetic nanoparticles due to their larger attractive forces. To achieve this stability, we will modify the nanoparticle surface using a method we have developed and successfully employed in prior work. PUBLIC HEALTH RELEVANCE: Sepsis is the tenth-leading cause of death in the U.S., the second-leading cause of death in non-coronary intensive care unit patients, and costs the health care system over $17 billion annually. The ensuing overuse of antibiotics has further resulted in antibiotic-resistant strains of bacteria, significantly increasing the risk of sepsis from hospital-acquired infections, particularly those from post-operative wound, trauma, and the urinary tract. The proposed effort is ultimately focused on rapid, ultra-sensitive diagnostic tests for bacteria that lead to sepsis, enabling the pathogen to be identified at the earliest possible stage to permit timely treatment with the correct antibiotic.