Adenosine Triphosphate Bioluminescence-Based Bacteria Detection Using Targeted Photothermal Lysis by Gold Nanorods.

Bacterial infections are common causes of morbidity and mortality worldwide; therefore, environmental contamination by bacterial pathogens represents a global public health concern. Consequently, a selective, rapid, sensitive, and in-field detection platform for detecting significant bacterial contamination is required to ensure hygiene and protect public health. Here, we developed a fast and simple platform for the selective and sensitive detection of bacteria by measuring adenosine triphosphate (ATP) bioluminescence following targeted photothermal lysis mediated by antibody-conjugated gold nanorods. This method employed both targeted photothermal lysis of bacteria by near-infrared (NIR) irradiation and highly selective detection of the lysed bacteria via ATP bioluminescence within 36 min (incubation, 30 min; NIR irradiation, 6 min). The use of the proposed method allowed limits of detection in pure solution of 12.7, 70.7, and 5.9 CFU for Escherichia coli O157:H7, Salmonella typhimurium, and Listeria monocytogenes, respectively. Additionally, bacteria were successfully detected on artificially inoculated plastic cutting boards. Furthermore, this method was highly specific, without cross-reaction among pathogenic bacteria. We believe that the proposed method has significant potential as an on-site diagnostic tool for applications associated with public health and environmental pollution monitoring.

Homogeneous and selective detection of cadmium ions by forming fluorescent cadmium-protein nanoclusters.

We synthesized fluorescent Cd nanoclusters (CdNCs) through a protein-directed method, and the synthesis method was utilized for a homogeneous, ultrasensitive, and selective detection of cadmium ion (Cd2+). CdNCs were synthesized using a modified protein-directed method for developing a rapid Cd2+ detection system. For rapid Cd2+ detection, the reaction time was reduced by optimizing the reaction conditions such as temperature, reducing agent concentration, and protein concentration. The synthesized CdNCs had ca. 2 nm diameter and showed strong fluorescence at 485 nm under 365 nm UV light. The fluorescence of the CdNCs increased with increasing Cd2+ concentrations, and the limit of detection in deionized water was 15.68 fM. This method enables the detection of Cd2+ through the Cd concentration-dependent formation of fluorescent CdNCs in tap, fountain, and pond water samples with detection limits of 0.75, 7.65, and 48.2 fM, respectively. The sensitivity and specificity of our method are comparable to those of several existing methods for Cd2+ detection. Furthermore, the system enables the homogeneous detection of Cd2+ without separation and washing, thereby broadening its application in analytical chemistry.