Wearable nucleic acid testing platform - A perspective on rapid self-diagnosis and surveillance of infectious diseases.

Wearable biosensors (WB) are currently attracting considerable interest for rapid detection and monitoring of biomarkers including metabolites, protein, and pathogen in bodily fluids (e.g., sweat, saliva, tears, and interstitial fluid). Another branch of WB termed wearable nucleic acid testing (NAT) is blossoming thanks to the development of microfluidic technology and isothermal nucleic acid amplification technique (iNAAT); however, there are only few reports on this. The wearable NAT is an emerging field of point-of-care (POC) diagnostics, and holds the promise for time-saving self-diagnosis, and evidence-based surveillance of infectious diseases in remote or low-resource settings. The use of wearable NAT can also be advanced to include molecular diagnosis, the identification of cancer biomarkers, genetic abnormalities, and other aspects. The wearable NAT provides the potential for evidence-based surveillance of infectious diseases when combined with internet connectivity and App software. To make the wearable NAT accessible to the end users, however, improvements must be made to the fabrication, cost, speed, sensitivity, specificity, sampling, iNAAT, analyzer, and a few other features. So, in this paper, we looked at the wearable NAT's most recent development, identified its difficulties, and defined its potential for managing infectious diseases quickly in the future. This is the wearable NAT review's first effort. We expect that this article will provide the concise resources needed to develop and deploy an efficient wearable NAT system.

Simple manual roller pump-driven valve-free microfluidic solution exchange system for urgent bioassay.

We introduce a simple-to-use manual roller pump (MRP)-driven and valve-free microfluidic system for sequential solution exchange, followed by a bioassay to detect protein. The polydimethylsiloxane (PDMS)/glass-based disposable device comprises a reaction chamber, multiple micro-flow channels (µFCs), and air vents. The practical solution exchange was realized by sequential injection and withdrawal of several solutions into and from the reaction chamber through constricted µFCs by utilizing changing air pressure of an MRP when a small cylindrical roller was pressed and rolled over a soft silicone tube using a finger. Furthermore, we investigated the effect of surface hydrophobicity on solution exchange. A sandwich fluorescence-based immunoassay to detect human interleukin 2 (IL-2) was performed using this simple microfluidic scheme to demonstrate its suitability for analytical bioassays. The system allowed quick IL-2 detection in 20 min in a pre-functionalized device with a detection limit of 80 pg mL-1 and a range of 125 pg mL-1 to 2.0 ng mL-1. We have thus developed a microfluidic scheme that non-experts can efficiently perform and that can be the fundamental module for low-cost bioassays necessary for emergencies and situations where resources are constrained.

Microfabricated electrochemical sensing devices.

Electrochemistry provides possibilities to realize smart microdevices of the next generation with high functionalities. Electrodes, which constitute major components of electrochemical devices, can be formed by various microfabrication techniques, and integration of the same (or different) components for that purpose is not difficult. Merging this technique with microfluidics can further expand the areas of application of the resultant devices. To augment the development of next generation devices, it will be beneficial to review recent technological trends in this field and clarify the directions required for moving forward. Even when limiting the discussion to electrochemical microdevices, a variety of useful techniques should be considered. Therefore, in this review, we attempted to provide an overview of all relevant techniques in this context in the hope that it can provide useful comprehensive information.

A simple micropump based on a freeze-dried superabsorbent polymer for multiplex solution processing in disposable devices.

We describe a simple micropump for disposable microfluidic devices. The pump is constructed using a freeze-dried disc of a superabsorbent polymer (SAP). The disc absorbs a solution in a flow channel and swells upward in a pumping chamber. Despite the simple structure of this device, the rate of absorption remains constant and can be adjusted by changing the composition of the SAP, its size, the dimensions of the flow channel and the medium to be absorbed. The pumping action can be initiated by applying an electrical signal using a switchable hydrophobic valve. The integrated approach of the SAP pump and switchable valve could facilitate the automatic processing of many solutions required for bioassay.

Switchable Hydrophobic Valve for Controlled Microfluidic Processing.

A simple microfluidic valve, without any moving parts, is presented that can control solution flow on demand in microchannels of many different materials using a low-power electric signal. Many independently operating valves can easily be integrated into complex microfluidic systems. The valve consists of a self-assembled monolayer (SAM) formed on a platinum electrode that is incorporated directly in the microchannel. The normally-on valve stops the solution flow due to a hydrophobic SAM on the electrode surface. The solution is allowed to pass the valve by applying a potential to the electrode, which removes the SAM due to reductive desorption. The valve operation is highly stable and has switching times of the order of 1 s. The valve is ideal for controlled solution manipulation in integrated micro-analytical systems and autonomous microfluidic systems.

Screening for phosphate solubilizing bacteria inhabiting the rhizoplane of rice grown in acidic soil in Bangladesh.

The objectives of the research were to isolate phosphate solubilizing bacteria (PSB) from the rhizoplane of rice (Oryza sativa L.) cv. BRRIdhan 29 cultivated in acidic soils of Tangail in Bangladesh and evaluate their performances in phosphate solubilization in both in vitro and in vivo conditions. A total of 10 bacterial strains were isolated and purified by repeated streak culture on nutrient agar medium. Upon screening, five isolates (OS01, OS03, OS07, OS08 and OS10) showed varying levels of phosphate solubilizing activity in agar plate and broth assays. Among them, the strain OS07 (B1) and two previously isolated PSB strains B2 and B3 were selected for evaluation for their performances in rice alone or in combination of TSP (triple super phosphate: P1) and rock phosphate (P2). Plant height and the number of tillers per plant were significantly increased by all PSB isolates when used in combination with TSP but PSB alone did not influence much on plant height and the number of tillers except B1. The levels of mineral nutrients content in rice plant tissues were generally increased by the application of the PSB in combination with TSP, while the performances of B1 isolate was superior in all aspects to B2 and B3 isolates.