RESUMO
Infectious diseases remain one of the major causes of death worldwide in developing countries. While screening via conventional polymerase chain reaction (PCR) is the gold standard in laboratory testing, its limited applications at the point-of-care have prompted the development of more portable nucleic acid detection systems. These include isothermal DNA amplification techniques, which are less equipment-intensive than PCR. Unfortunately, these techniques still require extensive sample preparation, limiting user accessibility. In this study, we introduce a novel system that combines thermophilic helicase-dependent amplification (tHDA) with a Triton X-100 micellar aqueous two-phase system (ATPS) to achieve cell lysis, lysate processing, and enhanced nucleic acid amplification in a simple, one-step process. The combined one-pot system was able to amplify and detect a target gene from whole-cell samples containing as low as 102 cfu/mL, and is the first known application of ATPSs to isothermal DNA amplification. This system's ease-of-use and sensitivity underlie its potential as a point-of-care diagnostic platform to detect for infectious diseases. Graphical abstract á .
Assuntos
DNA Bacteriano/genética , Escherichia coli O157/genética , Técnicas de Amplificação de Ácido Nucleico/métodos , DNA Helicases/metabolismo , DNA Bacteriano/análise , DNA Bacteriano/metabolismo , Infecções por Escherichia coli/microbiologia , Humanos , Limite de Detecção , Micelas , Octoxinol/química , Transição de Fase , Sistemas Automatizados de Assistência Junto ao Leito , Temperatura , Água/químicaRESUMO
Foodborne illnesses are a public health concern in the United States and worldwide. Recent outbreaks of Escherichia coli O157:H7 have brought to light the need for improved ways to detect foodborne pathogens and minimize serious outbreaks. Unfortunately, current methods for the detection of foodborne pathogens are time intensive and complex. In this study, we designed a spot immunoassay that uses a UCON-potassium phosphate salt aqueous two-phase system (ATPS) for the preconcentration of O157:H7. This platform was tested with samples of O157:H7 spiked in phosphate-buffered saline and milk. The ATPS was found to improve the detection limit of the spot test, yielding detection at 106 cfu/mL within 30 min. This is the first known application of ATPSs to spot immunoassays. Moreover, detection was successfully achieved without upstream processing or dilution of the sample prior to testing, thereby further simplifying the detection process. This technology's ease of use, sensitivity, and short time to result highlight its potential to advance the spot test as a viable diagnostic tool for foodborne pathogens.
Assuntos
ELISPOT/métodos , Escherichia coli O157/isolamento & purificação , Microbiologia de Alimentos/métodos , Leite/microbiologia , Animais , Sensibilidade e Especificidade , Fatores de TempoRESUMO
Paper-based systems have been widely investigated for developing point-of-care devices because of their simplicity, affordability, and ease of use. Recent advances have resulted in paper systems that have progressed beyond the historical "single-strip" format and allow for a larger range of functions. This review provides a summary of the advances that have been made to improve the utility of paper-based diagnostic tests for biosensing. Specifically, techniques for designing paper devices, including different geometries and chemical patterning to control fluid flow, are discussed. This review also examines novel approaches to improve paper-based assay sensitivities, such as sample preconcentration, signal amplification at the detection zone, and electrochemical methods.
