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Diagnosing Bacterial Infections by Nanoparticle Hybridization
Hyun Jung Chung, Assistant Professor, KAIST
The rapid and sensitive detection of bacterial pathogens is crucial for improving patient care by subsequent treatment with the appropriate antibiotics and preventing spread of the disease. Currently, culture-based assays or staining and microscopy remains the gold standard in the clinic, despite their long procedure times (several days), low sensitivity, and poor specificity. We have investigated various molecular labeling approaches which can be robustly applied in clinical settings for rapid and sensitive detection of bacterial pathogens. We first developed a nanoparticle labeling strategy to ubiquitously detect Gram-positive bacteria using a miniaturized nuclear magnetic resonance device (µNMR). We used small molecule antibiotics (vancomycin and daptomycin) and the Gram stain as targeting ligands, in a two-step bioorthogonal procedure, which allowed rapid and efficient labeling. To specifically identify each type of pathogen, we developed a nanoparticle hybridization technology based on detection of bacterial 16S rRNA sequences (Magneto-DNA nanoparticle system). The magneto-DNA technology allowed rapid and target-specific detection of different types of pathogenic bacteria with extremely high sensitivity in nine clinical specimens. In sum, the molecular sensing strategies based on nanoparticle labeling introduce robust and sensitive platforms for detecting various pathogens and diagnosis of infected patients.
Diagnosing Bacterial Infections by Nanoparticle Hybridization
Hyun Jung Chung, Assistant Professor, KAIST
The rapid and sensitive detection of bacterial pathogens is crucial for improving patient care by subsequent treatment with the appropriate antibiotics and preventing spread of the disease. Currently, culture-based assays or staining and microscopy remains the gold standard in the clinic, despite their long procedure times (several days), low sensitivity, and poor specificity. We have investigated various molecular labeling approaches which can be robustly applied in clinical settings for rapid and sensitive detection of bacterial pathogens. We first developed a nanoparticle labeling strategy to ubiquitously detect Gram-positive bacteria using a miniaturized nuclear magnetic resonance device (µNMR). We used small molecule antibiotics (vancomycin and daptomycin) and the Gram stain as targeting ligands, in a two-step bioorthogonal procedure, which allowed rapid and efficient labeling. To specifically identify each type of pathogen, we developed a nanoparticle hybridization technology based on detection of bacterial 16S rRNA sequences (Magneto-DNA nanoparticle system). The magneto-DNA technology allowed rapid and target-specific detection of different types of pathogenic bacteria with extremely high sensitivity in nine clinical specimens. In sum, the molecular sensing strategies based on nanoparticle labeling introduce robust and sensitive platforms for detecting various pathogens and diagnosis of infected patients.
Towards high performance detection of circulating tumor cells in whole blood
Marc Zinggeler, Research Assistant, IMTEK
Circulating tumor cells (CTCs) can be found in patient´s blood at typical concentrations of 0.3-100 cells per mL [1] and are becoming increasingly important as biomarkers for various cancers [2]. In this work we present a novel dead-end affinity filtration system for the enrichment of CTCs from whole blood with high efficiency, selectivity and throughput. At the heart of the system lies an affinity membrane, which was prepared by chemical surface modification of a commercial micro-filter to exclusively allow for the specific adhesion of target cells. The high selectivity of the developed capture surface was confirmed both on the level of proteins and cells. The generated membranes can be employed in a simple dead-end filtration setup (e.g. applied as syringe filters) ideally suited for application in point of care settings. First filtration experiments with whole blood and breast cancer cells showed that the membrane is highly permeable for blood cells and allows the efficient capture of cancer cells at high filtration pressure. This promising combination is expected to yield high quality enrichments and could enable the reliable identification and characterization of CTCs directly on the membrane surface (e.g. by immunocytochemistry).
Development of an Integrated Paper-based Molecular Diagnostic Platform
Manoharanehru Branavan, Research Student, Brunel University
Point-of-Care testing (POCT) devices have received immense attraction due to its simplicity, ease of use and swiftness. Microfluidic paper-based analytical devices (µPADs) are directly aimed for POC testing. Molecular diagnostics result in a more specific and sensitive assay than immunoassays with much smaller window time to diagnosis. Realizing molecular diagnostics on paper-based devices is a challenge that has been little addressed. A chitosan functionalized paper-based nucleic acid extraction method, isothermal amplification of Chlamydia trachomatis on paper-based devices, and endpoint detection on a nucleic acid lateral flow test strips are presented here. In addition, a proprietary integrated paper-based diagnostic device developed to perform lysate-in-to-answer-out in less than an hour with a limit of detection of 0.2 copies/µL and on-going studies to realise a complete system suitable for resource limited settings are also presented. The integrated device is capable of performing affordable, sensitive and specific, and equipment free molecular diagnostic assays in just 6 easy sequential processes.
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