Search

Owing to the frequent outbreak of dengue fever worldwide, a highly sensitive but in situ simple process diagnostic device is required to detect the dengue virus. However, the current immune affinity-based methods have sensitivity issues and nucleic acid-based diagnostic devices have not been suitable for field diagnosis due to the complexity in sample preparation. Here, a simple and fast nucleic acid-based diagnostic tool to directly detect dengue viruses in whole blood is demonstrated using a microbead-assisted direct sample preparation buffer (MB-buffer) and isothermal amplification (loop-mediated isothermal amplification, LAMP). To maximize the performance of the sample preparation process in the microfluidic chip platform, the chemical composition of the sample preparation buffer is simplified and combined with physical tools (heating and bead beating). The entire serial processes consisted of only (1) sample (whole blood) loading, (2) stirring for 90 s, (3) heating at 70 °C for 10 min, and (4) LAMP amplification in the simply designed microfluidic chip cartridge. A single syringe was utilized for sample loading and microfluidic solution transfer. Consequently, dengue viruses were qualitatively detected and discriminated with high sensitivity (LOD: 102 PFU per 200 μL of whole blood) in less than 1 hour without the use of any sophisticated system. [ABSTRACT FROM AUTHOR]

Public lavatories may cause the spread of infectious pathogens because they are enclosed spaces that both healthy people and patients can use. Thus, surface analysis for microbial contamination in public lavatories is of great importance because it is considered as an indicator of hygiene control. Herein, we developed polymerase chain reaction (PCR)-compatible surface sample preparation tools to increase the detection sensitivity and reproducibility within a short time using a semi-automatic detection system. The bacteria and viruses on different surfaces were collected using half A4-sized wipes. The wipes were treated through four different processes in a cartridge: (1) the pathogens were transferred from the wipes to the aqua phase using simple gentle vortexing; (2) the bacteria and viruses were concentrated by adsorption on the graphene surface; (3) the pathogens on the graphene layer were perfectly lysed using bead-beating tools and (4) the released DNA/RNA was collected in a microtube. The prepared nucleic acid sample was amplified using PCR or loop-mediated isothermal amplification (LAMP). At least one order of magnitude higher sensitivity was achieved using the wipe collecting method compared to that achieved using the normal swab method. This was confirmed using a semi-automatic cartridge for the wipe sampling in a lavatory hygiene test. [ABSTRACT FROM AUTHOR]