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Open access

Erel Lior, Tim Axelrod, Evgeni Eltzov, Ariel Kushmaro and Robert S. Marks

Abstract

The Lachish River has suffered from recurring pollution incidents for the past decade. On October 11th, 2017, another contamination in the river was sighted, as thousands of dead fish were found floating. Samples from the river were retrieved and tested through a whole cell bioluminescent bacterial bioreporter system as well as conventional analytical methods, and the results from both methods were analyzed and compared, even though initially these two collecting events were not coordinated. The information acquired from the whole cell reporter was consistent with that obtained from conventional methods. Both approaches indicated a large concentration of microorganisms as deduced from K802NR E. coli strain reaction and coliforms count. The high water conductivity measured in collected samples were closer downstream, and attributed to the diffusion of salts from the Mediterranean Sea which affected bacterial viability as seen from the decreased reaction of E. coli strains TV1061 and DPD2794. In addition, the bacterial indicators’ kinetic patterns have shown indication for the presence of a genotoxic substance from only one of the collection sites, which was tested positive for the herbicide Metazachlor, itself known to have genotoxic effects. The correlation between both approaches, along with the biosensor’s ability to assess biological influences, suggests that the whole cell bioluminescent bacterial bioreporter bioassay as an easy, simple and efficient approach for water toxicity monitoring.

Open access

Prima Dewi Sinawang, Dorin Harpaz, Luka Fajs, Raymond Chee Seong Seet, Alfred Iing Yoong Tok and Robert S. Marks

Abstract

Stroke is the second top leading cause of death globally. It is caused by an abrupt interruption of blood flow to the brain. In that course, brain natriuretic peptide (BNP) and its derivative N-terminal pro b-type natriuretic peptide (NT-proBNP), neurohormones produced mainly by the heart ventricles in response to excessive stretching of cardiomyocytes (heart muscle cells), are proven to be good biomarkers for heart failure diagnosis. Moreover, there is growing clinical interest of the use of NT-proBNP for stroke diagnosis and prognosis because it is significantly associated with cardioembolic stroke and secondary stroke reoccurrence, with sensitivity >90% and specificity >80%. However, in diagnostic settings, there is still a need to address the encountered analytical problems, particularly assay specificity and set up. In this study, a novel approach for NT-proBNP detection is demonstrated using an electrochemical immunoassay method. A label-free impedimetry immunosensor for stroke biomarker was developed using modified disposable screen-printed gold electrodes (SPGE) hosting specific anti-NT-proBNP capture antibody. The performance of our immunosensor was studied in the presence of NT-proBNP in both buffered and mock (porcine) plasma samples. A linear relation between the relative total resistance (ΔRtot) responses and the NT-proBNP concentrations in buffer was observed in a range from 0.1 to 5 ng mL-1 with a correlation coefficient (R2) of 0.94656. Overall, the biosensor has demonstrated the capability to quantitate NT-proBNP and differentiate such concentrations in a low concentration range, especially among 0, 0.1, 0.5, 1, and 3 ng mL-1 in plasma samples within 25 min. This range is valuable not only for classifying cardioembolic stroke (higher or equal to 0.5 ng mL-1), but also predicting the risk of secondary stroke reoccurrence (higher than 0.255 ng mL-1). Our biosensor has the potential to be used as an easy-to-use point-of-care test that is both accurate and affordable.