A Graduated Approach in the Abolition of Waterborne Diseases in Drinking Water Using an Indicator Based Approach and Nano Based Biosensors: A Review

The detection of pathogens continues to be a challenge in this present day despite the advancement in technology. The emergence of waterborne diseases is of great importance and their rapid detection and identification in water is of utmost importance. Water quality indicators and pathogen detection in environmental water samples is significant for maintaining safe drinking water. Traditional methods like the culture-based methods are laborious, time consuming and yield false-positive results. Hence, a lot of research has been put in developing rapid detection methods and quantifying water pathogens in water. These methods include the use of water quality indicators as early warning systems and nano material based biosensor detection methods. The review highlights “the state of the art” method for monitoring and detecting waterborne pathogens. The review summarizes the microbiological water quality indicators and biosensor based methods. These methods are time effective, sensitive, specific and therefore important in the diagnosis and prevention of waterborne diseases. Keywords: Waterborne Diseases, Biosensor based methods, Water quality indicators , Pathogens. DOI: 10.7176/JEES/10-3-07 Publication date:March 31st 202

Bacteriophage-Based Colorimetric Detection of Escherichia Coli in Drinking Water

One of the major safety causes in drinking water is from the bacteria contamination, especially in developing countries and resource-limited settings. Although many of these Escherichia coli (E. coli) strains in drinking water are nonpathogenic, they sever as the indicator for bacterial contamination. And, the more widely used method to detect E. coli in drinking water is to determine the activity of β-galactosidase (β-gal), which is released by E. coli. Rapid, sensitive and inexpensive detection of E. coli in drinking water can reduce the risk of food-borne bacteria infection and stop the disease widely spreading. In this degree research, phage-based colorimetric methods were developed to detect viable Escherichia coli (E. coli) concentration in drinking water. During the phage infection cycle, phages can specifically recognize target E. coli cells and release intracellular β-gal enzyme. Using our proposed novel biosensor strategies, the β-gal enzymatic activity as the indictor for the presence of E. coli in drinking water was measured. Firstly, T7 phage covalently conjugated to magnetic beads were used to capture, separate, and purity E. coli cells from drinking water. The released β-gal was determined using commercial colorimetric substrates. Due to the specific chemical and physical properties of nanomaterials, T7 phage were immobilized on magnetic nanoparticle to improve the capture efficiency of bacteria separation. Next, a novel enzyme-induced metallization multi-colorimetric assay was developed to monitor and measure β-gal activity, which was further employed for high-resolution colorimetric phage-enabled detection of E. coli. In order to improve the limit of detection and decrease the effect of the β-gal vary of in different E. coli strains, engineered phage (T7lacZ) carrying lacZ gene was furthermore built to force overexpression of β-gal in E. coli cells during phage infection. The uses of T7lacZ phage have been demonstrated to become a rapid, sensitive, and reliable colorimetric detection of viable E. coli

Nanotechnology Solutions for Global Water Challenges

The lack of clean and safe drinking water is responsible for more deaths than war, terrorism and weapons of mass destruction combined. This suggests contaminated water poses a significant threat to human health and welfare. In addition, standard water disinfection approaches such as sedimentation, filtration, and chemical or biological degradation are not fully capable of destroying emerging contaminants (e.g. pesticides, pharmaceutical waste products) or certain types of bacteria (e.g. Cryptosporidium parvum). Nanomaterials and nanotechnology based devices can potentially be employed to solve the challenges posed by various contaminants and microorganisms. Nanomaterials of different shapes, namely nanoparticles, nanotubes, nanowires and fibers have the ability to function as adsorbents and catalysts. These possess an expansive array of physicochemical characteristics deeming them highly attractive for the production of reactive media for water membrane filtration, a vital step in the production of potable water. As a result of their exceptional adsorptive capacity for water contaminants, graphene based nanomaterials have emerged as an area of significant importance in the area of membrane filtration and water treatment. In addition, Advanced Oxidation Processes (AOPs) together with or without sources of light irradiation or ultrasound, have been found to be promising alternatives for water treatment at near ambient temperature and pressure. Furthermore, the uses of visible light active titanium dioxide photocatalysts and photo-Fenton processes have shown significant potential for water purification. A wide variety of nanomaterial based sensors, for the monitoring of water quality, have also been reviewed in detail. In conclusion, the rapid and continued growth in the area of nanomaterial based devices offers significant hope for addressing future water quality challenges

Continuous chlorine detection in drinking water and a review of new detection methods

Chlorination is necessary to prevent epidemics of waterborne disease however excess chlorination is wasteful, produces harmful disinfection byproducts, exacerbates corrosion and causes deterioration in aesthetic qualities, leading to consumer complaints. Residual chlorine must be continuously monitored to prevent both under- and over-chlorination and factors including pH, temperature and fouling must be considered as these also affect the disinfectant strength of residual chlorine. Standard methods used by water utility companies to determine residual chlorine concentration in drinking water distribution systems are appraised and found to be unsuitable for continuous monitoring. A selection of newly developed methods for residual chlorine analysis are evaluated against performance criteria, to direct research towards the development of chlorine sensors that are suitable for use in water systems. It is found that fouling tolerance in particular is generally not well understood for these selected sensor technologies and that long-term trials in real systems is recommended

Luminescence Sensors Applied to Water Analysis of Organic Pollutants—An Update

The development of chemical sensors for environmental analysis based on fluorescence, phosphorescence and chemiluminescence signals continues to be a dynamic topic within the sensor field. This review covers the fundamentals of this type of sensors, and an update on recent works devoted to quantifying organic pollutants in environmental waters, focusing on advances since about 2005. Among the wide variety of these contaminants, special attention has been paid polycyclic aromatic hydrocarbons, pesticides, explosives and emerging organic pollutants. The potential of coupling optical sensors with multivariate calibration methods in order to improve the selectivity is also discussed

Emerging (Bio)Sensing Technology for Assessing and Monitoring Freshwater Contamination - Methods and Applications

Ecological Water Quality - Water Treatment and ReuseWater is life and its preservation is not only a moral obligation but also a legal requirement. By 2030, global demands will exceed more than 40 % the existing resources and more than a third of the world's population will have to deal with water shortages (European Environmental Agency [EEA], 2010). Climate change effects on water resources will not help. Efforts are being made throughout Europe towards a reduced and efficient water use and prevention of any further deterioration of the quality of water (Eurostat, European Comission [EC], 2010). The Water Framework Directive (EC, 2000) lays down provisions for monitoring, assessing and classifying water quality. Supporting this, the Drinking Water sets standards for 48 microbiological and chemical parameters that must be monitored and tested regularly (EC, 1998). The Bathing Water Directive also sets concentration limits for microbiological pollutants in inland and coastal bathing waters (EC, 2006), addressing risks from algae and cyanobacteria contamination and faecal contamination, requiring immediate action, including the provision of information to the public, to prevent exposure. With these directives, among others, the European Union [EU] expects to offer its citizens, by 2015, fresh and coastal waters of good quality

Development Of DNA-Based Biosensors And Antibacterial Additive

In the first project, an ultrasensitive assay has been developed for the detection and determination of Hg2+(aq) based on single-particle inductively coupled plasma-mass spectrometry (spICP-MS). In the presence of Hg2+(aq), AuNPs modified with a segment of single-stranded DNA can aggregate due to the formation of well-known thymine (T)-Hg2+-T complex. The spICP-MS can sensitively and quantitatively measure the degree of aggregation by the overall decrease in number of detected AuNPs or NP aggregates. Compared with most other Hg assays that use the same principle of aggregation-dispersion with DNA modified AuNPs, this spICP-MS-based method achieved a much lower detection limit of 0.031 part-per-trillion (155 fM) and a wider (10,000-fold) linear range up to 1 ppb. The method also showed good potential for practical applications with the environment and biomedical samples because it demonstrated minimal interference from the sample matrix. Moreover, this method, with its outstanding sensitivity could be expanded for the detection of other targets by designing the recognition unit on gold nanoparticles. In the second project, an ultrasensitive assay for biomolecules has been developed using graphene/gold nanoparticles (AuNPs) composites and single-particle inductively coupled plasma-mass spectrometry (spICP-MS). Thrombin was chosen as a model biomolecule for this study. AuNPs modified with thrombin aptamers were first non-selectively adsorbed onto the surface of graphene oxide (GO) to form GO/AuNPs composites. In the presence of thrombin, the AuNPs desorbed from the GO/AuNPs composites due to a conformation change of the thrombin aptamer after binding with thrombin. The desorbed AuNPs were proportional to the concentration of thrombin and could be quantified by spICP-MS. By counting the individual AuNPs in the spICP-MS measurement, the concentration of thrombin could be determined. This assay achieved an ultralow detection limit of 4.5 fM with a broad linear range from 10 fM to 100 pM. The method also showed excellent selectivity and reproducibility when a complex protein matrix was evaluated. Furthermore, the diversity of ssDNA ligands made this method a promising new technology for ultrasensitive detection of a wide variety of biomarkers in clinical diagnostics. In the third project, a novel sandwich bioreagent for sensitive and selective detection of E. coli bacteria was developed. The bioreagent combined antibody and aptamer as selective ligands and CuNPs as fluorescent signal labels. To further improve the method sensitivity, a hybridization chain reaction (HCR) amplification strategy was applied. E. coli bacteria in water were first captured by the anti-E. coli antibody modified magnetic beads and used to obtain the primer for HCR based on the aptamer. Ultimately, the fluorescent CuNPs were produced using the long length dsDNA formed during HCR as templates. The measured fluorescence intensity was directly dependent on E. coli concentration. A low detection limit of 5,200 CFU/mL and excellent selectivity were achieved under the optimal conditions. Moreover, the method exhibited great potential for detection of other bacteria in environmental analysis and clinical diagnostics. In the fourth project, the G-quadruplex/hemin (G/H) complex was applied as an additive to increase the antibacterial efficiency of H2O2 and avoid serious toxicity effect. The G/H complex catalyzes the decomposition of H2O2 and yields a higher hydroxyl radical (·OH) generation during the procedure. The formed ·OH has a higher antibacterial performance than the original H2O2. Using the G/H complex as an additive, the antibacterial activity of H2O2 was vastly enhanced against both Gram-positive and Gram-negative bacteria in vitro experiments. Furthermore, the designed antibacterial system was applied using a mouse wound model in vivo and showed outstanding prevention of wound infection and facilitation of wound healing. The study demonstrated the utility of using the G/H complex to help control both Gram-positive and Gram-negative infections

Biomedical waste management by using nanophotocatalysts: The need for new options

Biomedical waste management is getting significant consideration among treatment technologies, since insufficient management can cause danger to medicinal service specialists, patients, and their environmental conditions. The improvement of waste administration protocols, plans, and policies are surveyed, despite setting up training programs on legitimate waste administration for all healthcare service staff. Most biomedical waste substances do not degrade in the environment, and may also not be thoroughly removed through treatment processes. Therefore, the long-lasting persistence of biomedical waste can effectively have adverse impact on wildlife and human beings, as well. Hence, photocatalysis is gaining increasing attention for eradication of pollutants and for improving the safety and clearness of the environment due to its great potential as a green and eco-friendly process. In this regard, nanostructured photocatalysts, in contrast to their regular counterparts, exhibit significant attributes such as non-toxicity, low cost and higher absorption efficiency in a wider range of the solar spectrum, making them the best candidate to employ for photodegradation. Due to these unique properties of nanophotocatalysts for biomedical waste management, we aim to critically evaluate various aspects of these materials in the present review and highlight their importance in healthcare service settings

Hazard characterization of graphene nanomaterials in the frame of their food risk assessment: A review

Different applications have been suggested for graphene nanomaterials (GFNs) in the food and feed chain. However, it is necessary to perform a risk assessment before they become market-ready, and when consumer exposure is demonstrated. For this purpose, the European Food Safety Authority (EFSA) has published a guidance that has been recently updated. In this sense, the aim of this study is to identify and characterise toxicological hazards related to GFNs after oral exposure. Thus, existing scientific literature in relation to in vitro degradation studies, in vitro and in vivo genotoxicity, toxicokinetics data, in vivo oral studies, and other in-depth studies such as effects on the microbiome has been revised. The obtained results showed that the investigations performed up to now did not follow internationally agreed-upon test guidelines. Moreover, GFNs seemed to resist gastrointestinal digestion and were able to be absorbed, distributed, and excreted, inducing toxic effects at different levels, including genotoxicity. Also, dose has an important role as it has been reported that low doses are more toxic than high doses because GFNs tend to aggregate in the digestive system, changing the internal exposure scenario. Thus, further studies including a thorough toxicological evaluation are required to protect consumer's safety.Junta de Andalucía US-1259106, P18-RT-199