Overview
Biosensors are analytical devices that elicit a measurable signal in response to specific biological processes or the presence of a molecule. They offer crucial solutions in fields such as healthcare, environmental monitoring, and biotechnology with their ability to quantitatively measure a substance or pathway activity. This measurability makes biosensors the backbone of synthetic biology, as scientists need to reliably detect the results of their research in order to further improve upon it. As a result, the capability of synthetic biology is limited by the availability of consistent biosensors, making the lack of biosensors always an issue. Without more biosensors, the ability to gather accurate data that drives further research and innovation to solve issues like disease diagnosis and pollution detection is greatly obstructed. Due to our team's interest in synthetic biology research and firsthand experience with the lack of biosensors that could help our research, we were inspired to help solve this problem. A relatively recent paper from 2006 presented a library of about 2000 different promoters in E. coli K12 [1]. This presents an opportunity to develop a multitude of different biosensors. The goal of our project is to identify which promoters produce the highest level of fluorescence for several different molecules, most of which are involved with environmental issues, as a starting point for future biosensor development.
Figure 1. Abstract diagram of how a biosensor can be used to detect a given analyte by producing a green fluorescence [2]
The molecules used to screen the promoters with are the following: carbaryl, a popular insecticide; 3-phenoxybenzoic acid, a chemical compound used as an acaricide; lovastatin, a molecule used in drugs to lower cholesterol; butanoyl-homoserine lactone, a signaling molecule for quorum sensing; propoxur, nonfood carbamate insecticide; perfluorooctane sulfonate, a synthetic chemical for non-stick and stain-resistant consumer products; cis-naphthalene dihydrodiol, a polycyclic aromatic hydrocarbon commonly used to study microbial degradation; diethyl phthalate, a hazardous liquid for cosmetic ingredients or durability of products; and tartaric acid, an organic acid that occurs naturally in many fruits.
We hope that this unbiased presentation of which promoters elicit the largest response for each molecule will help focus and advance biosensor research and development.
Problem
At any point, when a problem arises, scientists need to find solutions, which requires some form of measurement to detect results. One such way is through biosensors. All the work relies on this detection to provide accurate results so that the proper solution can be implemented; otherwise, it’s a waste of time, effort, and money. As a result, it’s crucial that we have good sensors. Unfortunately, there’s a wide variety of promoters, and if an emergency arises, scientists won’t have time to test which promoters create the best biosensors for each problem. However, with our research, our findings will help scientists solve environmental problems like pollution, as well as health issues like high cholesterol. Certain promoters work better than others for certain molecules, so scientists can produce faster and create quicker results by utilizing the known pairings.
Inspiration
In our present day society the need for precise, real-time, and accessible detection of various molecules is growing. In fields such as healthcare, these detections can help with medical diagnostics by detecting biomarkers for diseases such as glucose for diabetes management, cardiac markers for heart diseases, or proteins for viral infections. The current goal is to provide rapid, accurate, and minimally invasive diagnostic tools. Another important field for detection is environmental monitoring. Monitoring pollutants include detecting heavy metals, pesticides, or plastics. These varying issues inspired us to focus on detection by building our research on the development of biosensors. We hope our project works towards the advancement in biosensors that can hopefully lead to improvements in the vast fields of healthcare and environmental monitoring.
Current Solutions
Currently, because of the lack of known biosensor and molecule pairings, synthetic biology tools are being used to create biosensors from scratch as needed by scientists. To create these biosensors, scientists have to rely on current literature, which is restricting. Therefore, the solution is limited to solutions portrayed in current literature. Certain molecules may not have a lot of known pairings, and if the scientists have to choose from current literature, their work may have inaccurate results from an inefficient molecule and promoter pairing.
Our Solution and Goals
The primary objective of our project is to identify optimal pairings between specific molecules and a library of about 2000 different promoters in E. coli K12 from a study published in 2006 [1], aiming to find the most effective combinations for detection using fluorescent biosensors. Given the vast number of promoters available, our approach refines the research process by enabling scientists to use pre-identified promoter and molecule pairings, significantly improving the efficiency of detection. This will allow researchers to address problems more quickly. Furthermore, molecules like carbaryl and 3-phenoxybenzoic acid are pesticides and pollutants that pose serious risks to our environment. We also studied diethyl phthalate, which is a synthetic substance in plastic that contributes to its flexibility. By providing a quick, easy, and reliable method for detecting these harmful substances, our project enables scientists to accurately monitor pollution levels and implement the necessary protective measures.
Implementation
Our project involves creating an efficient method for scientists by researching E. coli promoters that detect specific molecules and aid in developing biosensors. These E. coli promoters are key components of biosensors due to their ability to regulate gene expression in response to the presence of target molecules. When a promoter is sensitive to a specific molecule, it triggers the transcription of a reporter gene in the presence of that molecule. This then leads to a detectable signal, such as a fluorescence or luminescence, indicating the molecule’s presence and concentration. These promoters allow E. coli to sense environmental changes, enabling the bacteria to detect toxins, pollutants, or metabolic byproducts. Specific promoters for different molecules allows for the creation of highly selective biosensors which can provide real-time detection for a variety of fields such as environmental monitoring and medical diagnostics.
References
[1] Zaslaver, Alon et al. “A comprehensive library of fluorescent transcriptional reporters for Escherichia coli.” Nature methods vol. 3,8 (2006): 623-8. doi:10.1038/nmeth895
[2] Biological and Molecular Components for Genetically Engineering Biosensors in Plants - Scientific Figure on ResearchGate. Available from: https://www.researchgate.net/figure/Design-of-transcriptional-regulation-based-plant-biosensors-a-Working-principle-for_fig4_365279809
