Smartphone-Based Whole-Cell Biosensor Platform Utilizing an Immobilization Approach on a Filter Membrane Disk for the Monitoring of Water Toxicants

Abstract

Bioluminescent bacteria whole-cell biosensors (WCBs) have been widely used in a range of sensing applications in environmental monitoring and medical diagnostics. However, most of them use planktonic bacteria cells that require complicated signal measurement processes and therefore limit the portability of the biosensor device. In this study, a simple and low-cost immobilization method was examined. The bioluminescent bioreporter bacteria was absorbed on a filter membrane disk. Further optimization of the immobilization process was conducted by comparing different surface materials (polyester and parafilm) or by adding glucose and ampicillin. The filter membrane disks with immobilized bacteria cells were stored at −20 °C for three weeks without a compromise in the stability of its biosensing functionality for water toxicants monitoring. Also, the bacterial immobilized disks were integrated with smartphones-based signal detection. Then, they were exposed to water samples with ethanol, chloroform, and H2O2, as common toxicants. The sensitivity of the smartphone-based WCB for the detection of ethanol, chloroform, and H2O2 was 1% (v/v), 0.02% (v/v), and 0.0006% (v/v), respectively. To conclude, this bacterial immobilization approach demonstrated higher sensitivity, portability, and improved storability than the planktonic counterpart. The developed smartphone-based WCB establishes a model for future applications in the detection of environmental water toxicants.

Biolum’ RGB: A Low-Cost, Versatile, and Sensitive Bioluminescence Imaging Instrument for a Broad Range of Users

“…In the field, smartphone compactness and RGB spectral detection can be an advantage when combined with bright bioluminescent protein, such as that reported in the literature, when using antibodies grafted with Nluc-based ratiometric biosensors. , Alternatively, smartphone-based bioluminescent imaging methods have been used to quantify bioluminescent or chemiluminescent biomarkers emitted from biological fluids (blood, saliva, and sweat) and from bioreporters expressed HEK cells, E. coli, or Aliivibrio fischeri used to monitor environmental or chemical toxicity. These approaches contribute to the global trend of developing rapid, inexpensive, and highly accessible diagnostic techniques deployed on-site.…”

Illuminating Progress: The Contribution of Bioluminescence to Sustainable Development Goal 6—Clean Water and Sanitation—Of the United Nations 2030 Agenda

“…( b ) Smartphone-based BL whole-cell biosensor for monitoring of water toxicants, reproduced from Ref. [ 79 ]. ( c ) Orthogonal paper-based biosensor for mercury (II) combining BL and colorimetric detection, reproduced from [ 40 ] with permission.…”

Microfluidic technology and its application in the point-of-care testing field

“…Bacterial suspension refers to bacteria in a suspended state in the liquid, bacterial lyophilization refers to bacteria that are made into lyophilized powder, and bacterial fixation is that bacteria are fixed to disposable sample pools, fiber optics, or chips. For example, the optical fiber monitoring system developed by Eltzov's group to detect toxic pollutants in water is to fix bacteria on the optical fiber ( Axelrod et al, 2016 ; Ma et al, 2020 ). Jouanneau et al designed a microfluidic biosensor for detecting heavy metals.…”