Biosensors & Bioelectronics

Biosensor performance and readout are critically dependent upon sensor surface characteristics. It is vital that key steps in sensor construction, such as base layer polymer/Self-Assembled Monolayer (SAM) deposition and bioreceptor tethering, are controlled tightly in order to achieve high sensitivity, specificity and reproducibility. Here, we present a rapid, semi-quantitative method by which key biosensor surface features can be characterised using chemiluminescence. This technique, which we have termed midland blotting, permits the detection of biosensor surface components through the attachment of a HorseRadish Peroxidase (HRP)-conjugated reagent to the target of interest. Upon addition of luminol-based substrate, HRP generates a reagent which emits light when it decays. The light signal is proportional to the bound HRP on the sensor surface. We show here that midland blotting allows the measurement and validation of various important surface features including: (1) availability of functional groups on the polymer or SAM layer; (2) bioreceptor tethering and (3) analyte binding. Midland blotting is rapid, cost-effective and allows for much faster optimisation of biosensor surface design. This method also provides a simple way of troubleshooting and can explain sensor performance when combined with readout data. In this report, we have focussed on midland blotting for electrochemical immunosensors as a proof of concept, but this technique is readily applicable to all biosensor systems.

Since the introduction of nanotechnology there has been an increase in the use of nanoparticles (NPs) in the development of biosensors for the detection of bacterial pathogens. Consequently, research exploring their potential toxicity has also increased as some have been shown to be harmful depending on their size, shape, and chemical composition making it imperative that we understand their possible harm to humans and the environment. In this study we investigated the potential toxicity of three differently coated FeO Magnetic NPs (MNPs), amine, carboxyl, and polyaniline, on the Caenorhabditis elegans (C. elegans) nematode. Briefly, C. elegans were exposed to the singular coated-MNPs types at a concentration of 100 μg/mL and assessed for physiological effects on their metabolism, reproduction, longevity, and oxidative stress resistance. Exposure to singular coated-MNPs corresponded with a statistical decrease in their metabolic and acute oxidative stress resistance abilities, and revealed a trend towards lower reproduction and longevity. Taken together, these results add to the growing evidence that FeO coated-MNPs have an in vivo toxic effect on C. elegans. These findings advocate for a need to take safety precautions when discarding FeO coated-MNPs as they may pose a toxic health hazard to our environment and health.

Live cell-based sensor reporter systems (so-called sensor cells) were employed to detect host defense systems, including DNA damage response, stimulated by nanoparticles (NPs). Our previous work established the use of DNA damage-detecting sensor cells containing the B-cell translocation gene 2(BTG2) promoter-reporter plasmid and showed that Toll-like receptors (TLRs) are involved in the cellular response and uptake of TiO2 NPs. These results suggested that TLRs could be involved in many cellular responses. However, the effect of TLRs on DNA damage induced by TiO2 NPs is unknown. Here we investigated the role of TLR 3 and 4 in DNA damage induced by PEG- 2 NPs reduces DNA damage response compared to unmodified TiO2 NPs. The overexpression of TLR3 reduces DNA damage mediated by both TiO2 and PEG-TiO2 NPs. In contrast, overexpression of TLR4 increases the DNA damage response induced by TiO2 NPs. The results indicate that co-transfection of TRL4 expression vector affects the sensitivity of DNA damage response, but does not affect the detection limit of the DNA damage response. These finding will aid in understanding the molecular interaction mechanisms between NPs and cells.