ABSTRACT
To ensure clean drinking water, viable pathogens in water must be rapidly and efficiently screened. The traditional culture or spread-plate process-the conventional standard for bacterial detection-is laborious, time-consuming, and unsuitable for rapid detection. Therefore, we developed a colorimetric assay for rapid microorganism detection using a metabolism-based approach. The reaction between a viable microorganism and the combination of 2-(2-methoxy-4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium sodium salt (WST-8) and 1-methoxy-5-methylphenazinium methyl sulfate (mPMS) results in a color change. In combination with a microplate reader, WST-8-mPMS reactivity was leveraged to develop a colorimetric assay for the rapid detection of various bacteria. The detection limit of the WST-8-mPMS assay for both gram-negative and gram-positive bacteria was evaluated. This WST-8-mPMS assay can be used to perform colorimetrical semi-quantitative detection of various bacterial strains in buffers or culture media within 1 h without incubation before the reaction. The easy-to-use, robust, rapid, and sensitive nature of this novel assay demonstrates its potential for practical and medical use for microorganism detection.
ABSTRACT
Chlamydia trachomatis (C. trachomatis) is one of the most prevalent preventable sexually transmitted diseases (STDs) in the world. In women, C. trachomatis infection can lead to long-term complications such as pelvic inflammatory disease (PID), and other related conditions such as ectopic pregnancies and even tubal factor infertility. These complications are preventable given early detection and clinical intervention, but these efforts are often hampered by asymptomatic silent infections, and non-compliance to screenings for STDs. Some women do not get tested out of concerns for violation of privacy, and fear of discomfort. Clinicians often use a multitude of tests to determine if a patient is infected by C. trachomatis, including a Polymerase Chain Reaction (PCR) test of First catch urine (FCU) samples. However, these tend to be inconvenient to store and transport, as they carry risk of spillage and have stringent refrigeration requirements. Moreover, given the gold-standard recommendations set forth by the Centres for Disease Control (CDC), the current technique can be inconvenient in remote areas where refrigeration and transport may not always be reliable. The current study therefore looks at the potential of a self-collected vaginal swab device that relies on Nucleic Acid Amplification Tests (NAATs), is dry-stored, and does not require refrigeration, to detect the presence of C. trachomatis in women. The study found evidence to suggest that the self-collection device has the potential to aid clinicians in the diagnosis of C. trachomatis in women when compared to doctor-collected vaginal discharge samples as the designated standard, FCU, and blood serology. Moreover, as a self-collection device it has the potential to break down some of the barriers to STD screening especially in young women, such as violation of privacy. The device therefore has a potential to encourage screening and therefore a potentially effective tool in the fight against the spread of preventable sexually transmitted diseases.
ABSTRACT
Cellular chemotaxis has been the subject of a variety of studies due to its relevance in physiological processes, disease pathogenesis, and systems biology, among others. The migration of cells towards a chemical source remains a closely studied topic, with the Boyden chamber being one of the earlier techniques that has successfully studied cell chemotaxis. Despite its success, diffusion chambers such as these presented a number of problems, such as the quantification of many aspects of cell behaviour, the reproducibility of procedures, and measurement accuracy. The advent of microfluidic technology prompted more advanced studies of cell chemotaxis, usually involving the social amoeba Dictyostelium discoideum (D. discoideum) as a model organism because of its tendency to aggregate towards chemotactic agents and its similarities to higher eukaryotes. Microfluidic technology has made it possible for studies to look at chemotactic properties that would have been difficult to observe using classic diffusion chambers. Its flexibility and its ability to generate consistent concentration gradients remain some of its defining aspects, which will surely lead to an even better understanding of cell migratory behaviour and therefore many of its related biological processes. This paper first dives into a brief introduction of D. discoideum as a social organism and classical chemotaxis studies. It then moves to discuss early microfluidic devices, before diving into more recent and advanced microfluidic devices and their use with D. discoideum. The paper then closes with brief opinions about research progress in the field and where it will possibly lead in the future.
ABSTRACT
(1) Background: The complexity, amount of time, and the large amount of resource required to perform gold-standard bacteria culture procedures makes it difficult to perform timely pathogenic analyses, especially in areas where such resources are not readily available. A paper-based biochemical analytical tool can potentially tackle problems economically in terms of time and convenience, potentially finding utility in applications where simple and timely detection of bacteria is necessary; (2) Methods: The utility of paper-based MTT-PMS strips was tested using a simple colorimetric analytical methodology; (3) Results: Sufficient evidence was obtained to suggest that the strips can potentially be used as a rapid and convenient early, alternative bacteria screening tool for a variety of applications; (4) Conclusions: The potential of strips for the rapid detection of bacteria compared to standard bacteria culture is a key advantage in certain clinical, agricultural, and environmental applications.