Validation of a membrane touch biosensor for the qualitative detection of IgG class antibodies to herpes simplex virus type 2.

A novel type of biosensor was assessed for application to the qualitative determination of circulating antibodies to herpes simplex virus type 2 (HSV-2). The device utilises a high activity HSV-2 type specific gG2 antigen for antibody capture and commercially available ELISA reagents. The study compares the diagnostic performance of a prototype HSV-2 biochip to well-established in vitro tests routinely applied in clinical procedures. A panel of human serum samples (n = 60) previously characterised for HSV-2 serological status using the DiaSorin LIAISON® HSV-2 chemiluminescent immunoassay were assayed on the HSV-2 biochip and the Focus Diagnostics HerpeSelect® 2 ELISA IgG kit to determine concordance with the predicate test method. Sensitivity and specificity of the HSV-2 biochip were found comparable to both the DiaSorin and Focus test methods. Sample index values calculated from the immunoassay response of the biochip's coulometric sensors indicated a high degree of linear correlation of the dataset with the corresponding index values from the DiaSorin LIAISON® test (r2 0.8799) and Focus HerpeSelect® test (r2 0.8794). The HSV-2 biochip demonstrated excellent diagnostic performance in qualitative and semi-quantitative measurements, matching closely the performance of two diagnostic industry standard predicate methods.

Quantum Dot Nanotoxicity Investigations Using Human Lung Cells and TOXOR Electrochemical Enzyme Assay Methodology.

Recent studies have suggested that certain nanomaterials can interfere with optically based cytotoxicity assays resulting in underestimations of nanomaterial toxicity. As a result there has been growing interest in the use of whole cell electrochemical biosensors for nanotoxicity applications. Herein we report application of an electrochemical cytotoxicity assay developed in house (TOXOR) in the evaluation of toxic effects of mercaptosuccinic acid capped cadmium telluride quantum dots (MSA capped CdTe QDs), toward mammalian cells. MSA capped CdTe QDs were synthesized, characterized, and their cytotoxicity toward A549 human lung epithelial cells investigated. The internalization of QDs within cells was scrutinized via confocal microscopy. The cytotoxicity assay is based on the measurement of changes in cellular enzyme acid phosphatase upon 24 h exposure to QDs. Acid phosphatase catalyzes dephosphorylation of 2-naphthyl phosphate to 2-naphthol (determined by chronocoulometry) and is indicative of metabolic activity in cells. The 24 h IC50 (concentration resulting in 50% reduction in acid phosphatase activity) value for MSA capped CdTe QDs was found to be 118 ± 49 µg/mL using the TOXOR assay and was in agreement with the MTT assay (157 ± 31 µg/mL). Potential uses of this electrochemical assay include the screening of nanomaterials, environmental toxins, in addition to applications in the pharmaceutical, food, and health sectors.