Abstracts

We recently have shown that firefly luciferases pH-sensitivity can be harnessed for intracellular pH indication and for heavy metal sensing in water samples. We have also shown that different luciferases display distinct heavy metal selectivities. However, there are drawbacks that need to be addressed to bring this technology to practical uses, such as the red-shifted spectra of most firefly luciferases at high temperatures which limit the application for mammalian cells, and the broad selectivity for different metals such as Zn, Cd, Hg. These issues can be addressed by selection of new luciferases and also by engineering the proton/metal binding sites. We show that AmyLuc™ color tuning luciferase, was the best option among firefly luciferases tested for mammalian cells pH-sensing, and also a promising tool for BL color tuning detection of cadmium, being successfully applied for educational purposes to demonstrate the effect of heavy metals and pH on enzyme function. To be effective for hands on field biosensor, however, such methodology must be associated to easy, cheap and portable photodetection devices associated to quantification programs. Based on the previously demonstrated applicability of smartphone technology for bioluminescence assays (Roda et al., 2014), and the availability of cell phones with increasingly sensitive CCD cameras, we recently developed smartphone based applicative for luminescent colorimetric analysis of cadmium contamination of water. The methodology can be harnessed not only for metal sensing, but also for intracellular pH sensing.