The detection of Legionella in environmental samples, such as water, is crucial for public health monitoring and outbreak prevention. Although effective, traditional detection methods, including culture-based techniques and polymerase chain reaction, have limitations such as long processing times, trained operators, and the need for specialized laboratory equipment. Biosensing technologies offer a promising alternative due to their rapid, sensitive, cost-effectiveness, and on-site detection capabilities. To summarize the current advancements in biosensor development for detecting Legionella in environmental samples, we used ‘Legionella’ AND ‘biosensors’ NEAR ‘environmental samples’ OR ‘water’ as keywords searching through the most relevant biomedical databases for research articles. After removing duplicates and inadequate articles from the n.1268 records identified using the PRISMA methodology exclusion criteria, we selected n.65 full-text articles which suited the inclusion criteria. Different results between the studies describing the current biosensing techniques, including optical, electrochemical, magnetic, and mass-sensitive sensors were observed. For each biosensing technique, sensitivity, specificity, and detection limits were evaluated. Furthermore, the integration of nanomaterials, microfluidics, and portable devices in biosensor systems’ design were discussed, highlighting their role in enhancing detection performance. The potential challenges and future directions in the field of Legionella biosensing were also addressed, providing insights into the feasibility of implementing these technologies in routine environmental monitoring. Undoubtedly, biosensors can play a crucial role in the early detection and management of Legionella infections and outbreaks, ultimately protecting public health and safety.

We present the design, fabrication, and testing of a low-cost, miniaturized detection system that utilizes chemiluminescence to measure the presence of adenosine triphosphate (ATP), the energy unit in biological systems, in water samples. The ATP–luciferin chemiluminescent solution was faced to a silicon photomultiplier (SiPM) for highly sensitive real-time detection. This system can detect ATP concentrations as low as 0.2 nM, with a sensitivity of 79.5 A/M. Additionally, it offers rapid response times and can measure the characteristic time required for reactant diffusion and mixing within the reaction volume, determined to be 0.3 ± 0.1 s. This corresponds to a diffusion velocity of approximately 44 ± 14 mm²/s.

Nitrite (NO₂⁻) has long been recognized as a contaminant of concern due to its detrimental effects on both human health and the environment. As a result, there is a continuing need to develop sensitive, real-time, low-cost, and portable systems for the accurate detection of trace levels of NO₂⁻ in drinking water. We present a novel, low-cost, and easy-to-fabricate amperometric sensor designed for detecting low concentrations of NO₂⁻ in drinking water. The fabrication technique involves the electrodeposition of manganese and copper oxides onto a carbon working electrode. CuO and MnO₂ act synergistically as efficient catalysts for the electrooxidation of nitrite to nitrate (NO₃⁻) thanks to their complementary redox properties. The resulting sensor exhibits high catalytic activity toward the electrooxidation of NO₂⁻, with a sensitivity of 10.83 μA/µM, a limit of detection (LOD) of 0.071 µM, and a good linear dynamic concentration range (0.2–60 µM). The sensor’s performance was evaluated against potential interfering analytes (NO₃⁻, Cl⁻, NH₄⁺, and NH₂Cl), all of which showed negligible interference. Reproducibility (maximum standard deviation 2.91%) and repeatability (usable up to three times) were also evaluated.

This chapter aims to provide information on the progress of research into water quality analyses, providing an overview of the state of the art, including novel research achievements, in the detection of water contaminants. After a brief introduction to the main sensing systems’ characteristics, the attention will be devoted to two different classes of pollutants: organic and inorganic. Microbiological analyses concerning the monitoring of bacterial load in water and chemical analyses with a special focus on mercury, related to heavy metal pollution, and nitrogen compounds, i.e. nitrate ion and ammonium ion, are discussed. Particular attention will be devoted to all sensing systems that are in principle portable and able to make real-time measurements in situ.

This work presents the design and optimization of a miniaturizable, high-sensitivity system for real-time detection of adenosine triphosphate (ATP)-the primary energy carrier in biological systems-in water samples. Detection was based on the chemiluminescent ATP-luciferin driven reaction, monitored using a silicon photomultiplier (SiPM). Three different set-up configurations were investigated, focusing on the effects of reaction chamber size and total solution volume. The system achieved a minimum detectable ATP concentration of 0.05 nM, with a limit of detection (LoD) of 0.03 nM and a sensitivity of 11.9 A/M.

In this work, we present an innovative system for the rapid detection of bacterial contamination in water samples, exploiting chemiluminescence reaction in the presence of bacterial adenosine triphosphate (ATP). It is formed by a closed box in which reagents and ATP from water samples are put in a spectrophotometric-grade quartz cuvette on a silicon photomultiplier (SiPM) that converts the photons revealed into electrical signals. A commercial kit for bacterial load detection in water samples employing ATP chemiluminescent reaction was tested, and its filtration and lysis efficiencies were assessed. A comparison between the new system and the luminometer, the standard device for chemiluminescence detection, was then conducted. Firstly, calibration curves for both systems were obtained using different ATP concentrations, resulting in a Limit of Detection (LoD) of 0.03 nM for the SiPM-based system and 0.01 nM for the luminometer. Afterwards, water samples artificially contaminated with E. coli were prepared to compare the detection efficiency of both systems using the commercial kit for sample processing. A cultural method analysis was also conducted to validate the obtained results. ATP concentrations derived from the three detection strategies showed great consistency, underlying the high sensitivity of the new low-cost, miniaturizable and potentially remotely controlled system developed.