Portable Device for Quick Detection of Viable Bacteria in Water

Abstract

(1) Background: Access to clean water is a very important factor for human life. However, pathogenic microorganisms in drinking water often cause diseases, and convenient/inexpensive testing methods are urgently needed. (2) Methods: The reagent contains 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and phenazine methosulfate (PMS) and can react with succinate dehydrogenase within bacterial cell membranes to produce visible purple crystals. The colorimetric change of the reagent after reaction can be measured by a sensor (AS7262). (3) Results: Compared with traditional methods, our device is simple to operate and can provide rapid (i.e., 5 min) semi-quantitative results regarding the concentration of bacteria within a test sample. (4) Conclusions: This easy-to-use device, which employs MTT-PMS reagents, can be regarded as a potential and portable tool for rapid water quality determination.

Fundamental Studies of Rapidly Fabricated On-Chip Passive Micromixer for Modular Microfluidics

“…Usually, at this micrometer size scale and with liquids flowing relatively slowly, the flow is laminar and confluence liquids tend to flow side by side. Due to the importance of mixing in modular microfluidic chips, many excellent researchers have developed different mixing techniques, based on geometries that reduce diffusion length scales or induce secondary flow, incorporate miniature mixing balls or rods, utilize cross flows or alternating flow from the inlets, pulse one of the reagents, or apply electric, magnetic, or ultrasonic vibratory fields [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 ]. Generally, these mixing techniques can be broadly classified into two types: passive and active.…”

Detecting Bacterial Cell Viability in Few µL Solutions from Impedance Measurements on Silicon-Based Biochips

“…Existing bacterial detection techniques are primarily divided into traditional culture methods, e.g., colony counting of diluted or whole sample solutions to determine bacterial concentration, which takes a long time to obtain results (24–48 h) and which needs an incubator, and biotechnological approaches, e.g., polymerase chain reaction amplification (PCR), fluorescence analysis, and traditional enzyme-linked immunoassay (ELISA) [ 2 ]. Gregori et al [ 3 ] monitored the viability of E. coli cells from freshwater and seawater using the live-dead protocol developed by Barbesti et al [ 4 ] based on simultaneous staining of bacteria nucleic acids by a permeant (SYBR Green I) and an impermeant (PI) fluorescent probe and the interpretation of the green versus the red fluorescence cytograms.…”

“…Rosenberg et al investigated the viability of adherent gram-positive Staphylococcus epidermidis and gram-negative Escherichia cells and pointed out that viability staining results of adherent cells should always be validated by an alternative method, preferably by cultivation [ 13 ]. Liao et al optimized detectability of E. coli cells using fluorescence by using 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide (MTT) and phenazine methosulfate (PMS) as new reagents [ 2 ]. Ou et al assessed four methods for viability analysis for E. coli , namely SYTO 9: propidium iodide fluorescence intensity ratio, an adjusted fluorescence intensity ratio, single-spectrum support vector regression (SVR) and multi-spectra SVR, and found that multi-spectra SVR is best suited [ 14 ].…”

“…The working volume of 384, 1536 or 3456 plates amounts to 25.0 µL, 1.5 µL, and 1.0 µL, respectively. As reviewed by Liao et al [ 2 ] the biotechnological methods have many disadvantages including cost of materials (enzymes, antibodies, and antigens), low-temperature storage requirements, skilled and experienced operational needs, combination of different experimental methods with different instruments, and long and complicated operation methodology. Combining results from flow cytometry and from live/dead fixable dead cell stain kits is a too long and complicated operation methodology for online screening of bacterial cell viability, e.g., to determine intermediate states of bacterial cell viability [ 15 ] and to detect the long-term effects of drugs.…”

Editorial for the Special Issue on Security and Sensing Devices for Healthcare Technologies

“…In the paper [ 5 ], Portable Device for Quick Detection of Viable Bacteria in Water, an easy-to-use, lightweight device that can be used to detect water quality level at rapid pace is presented. The device exploits different chemicals such as dimethylthiazol, diphenyltetrazolium, and phenazine methosulfate when they are used in bacterial cell membranes.…”