Development of a paper-based microanalysis device doped with multi-walled carbon nanotubes for in vitro evaluation of fluorene cytotoxicity.

• Developing a mini paper-based device to detect fluorene cytotoxicity in 10 µL sample. • The MWCNTs/μ-PAD allowed a sampling volume of 10.0 μL, which is 50.0 times less than the sampling volume required with a conventional electrode (500 μL). • This device is comparable to the MTT method in fluorene cytotoxicity analysis. Developing a cost-effective and simple micro-analysis tool has long been an important objective in the toxicological detection of fluorene. In this study, a disposable paper-based micro-analysis device (μ-PAD) was designed using graphite doped with multi-walled carbon nanotubes (MWCNTs) to hand draw the electrode (MWCNTs/μ-PAD). We investigated the feasibility of the designed MWCNTs/μ-PAD as a cell-sensing platform using voltammetry measurements. Its application for evaluating the cytotoxicity of fluorene was studied based on the electrochemical determination of human breast cancer cells induced by fluorene. The results showed a dose-dependent toxicity effect of fluorene on cellular activity. The measurements were comparable with those obtained using a methyl-thiazolyl-tetrazolium assay. The detection limit of the MWCNTs/μ-PAD for human breast cancer cells was as low as 4.00 × 103 cells·mL−1 owing to the enhanced catalytic activity of the MWCNTs. Notably, the MWCNTs/μ-PAD—which had a diameter of 7.00 mm—allowed a sampling volume of 10.0 μL, which is 50.0 times less than the sampling volume required with a conventional electrode (500 μL). Advantages such as the simplicity of manufacture, low consumption, low cost, rapid detection, and disposability, suggest that the MWCNTs/μ-PAD could provide new opportunities and directions for in vitro microanalysis. [ABSTRACT FROM AUTHOR]