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• Article
• Open Access
• Published: 03 July 2020

Noninvasive and safe cell viability assay for Paramecium using natural pigment extracted from food

• Kyohei Yamashita1 &
• Eiji Tokunaga1 

volume 10, Article number: 10996 (2020) Cite this article

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Subjects

• Biochemistry
• Biological techniques
• Biophysics
• Biotechnology
• Cell biology
• Chemical biology
• Drug discovery
• Environmental sciences
• Medical research
• Microbiology
• Optics and photonics
• Plant sciences

AbstractNoninvasive, safe and cost-effective cell viability assay is important in many fields of biological research such as cell culture and counting. We examined ten typical natural pigments extracted from food to find that Monascus pigment (MP) or anthocyanin pigment (AP: purple sweet potato and purple cabbage) with Tris (Trimethylolaminomethane) works as a good indicator of viability assay for dye exclusion test (DET) of Paramecium. This was confirmed spectrally by scan-free, non-invasive absorbance spectral imaging A (x, y, ?) microscopy. We developed a new method of cell capture using a metal mesh to confine live Paramecium in a restricted space. This has the advantage that a low-cost and robust capture can be fabricated without using special equipment, compared to a conventional lab-on-a-chip. As a result, MP and AP stained dead cells as quick as methylene blue (MB), a synthetic dye conventionally used in DET within 1 min when treated with microwave and benzalkonium chloride. The natural pigments with Tris had little effect on inhibiting the growth of Paramecium, but MB killed all the cells within 1 h. MP is most useful because it allows non-invasive DET without Tris. This approach provides less invasive and safe DET.