On-Chip Dielectrophoretic Separation and Concentration of Viable, Non-Viable and Viable but Not Culturable (VBNC) Escherichia coli

Although bacterial culture remains the gold standard for detection of viable bacteria in environmental specimens, the typical time requirement of twenty-four hours can delay and even jeopardize appropriate public health intervention. In addition, culture is incapable of detecting viable but not culturable (VBNC) species. Conversely, nucleic acid and antibody-based methods greatly decrease time to detection but rarely characterize viability of the bacteria detected. Through selection by membrane permeability, the method described in this work employs positive dielectrophoresis (pDEP) for separation and purification of viable and VBNC species from water and allows concentration of bacteria for downstream applications

Characterization of polyaniline-coated magnetic nanoparticles for application in a disposable membrane strip biosensor

We investigated the electrical properties of polyaniline-coated magnetic nanoparticles as a signal transducer for application in a disposable membrane strip biosensor. The size of these particles (~100 nm) was investigated by a transmission electron microscope. Electrical properties of these nanoparticles were investigated by four-point probe measurements and I-V measurements. Polyaniline-coated magnetic nanoparticles had a resistivity of 0.385 Ω cm and showed ohmic behavior. Resistance decreased with increasing concentration of polyaniline. We also demonstrated that the resistance decreased with increasing concentration of biotinylated IgG conjugated with these nanoparticles

DNA-based electrochemical nanobiosensor for the detection of Phytophthora palmivora (Butler) Butler, causing black pod rot in cacao (Theobroma cacao L.) pods

© 2019 Elsevier Ltd A nanobiosensor was developed for the electrochemical detection of Phytophthora palmivora, a notorious pathogen of cacao causing severe crop loss. Sandwich hybrids between two oligonucleotide probes and the genomic DNA of P. palmivora were prepared and electrochemically detected. The oligonucleotide probes were designed based on the ITS sequence of the P. palmivora field isolates. The detection of sandwich hybrids with P. palmivora genomic DNA and the selectivity of the nanobiosensor towards it compared to other cacao-associated fungal pathogens were demonstrated. The detection limit was determined to be at 0.30 ng DNA μL−1. Detection of P. palmivora DNA on cacao samples was also demonstrated. The result of the preliminary analysis on cacao pod samples shows the potential of the developed nanobiosensor for reliable and more cost-effective analysis of field samples