Team:TecCEM/Description
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Disrupting Disruptors: A biosensor for the detection of EDCs
Key Concepts: Microplastics, Endocrine Disrupting Chemicals (EDCs), Biosensor, Human Estrogen Receptor (hER⍺, ESR1), Piezoelectric Sensor.
From all the pollutants, why did we choose Endocrine Disrupting Chemicals?
Microplastics represent a big problem, they represent perhaps one of the biggest dangers of our time. They are generated by the incomplete degradation of materials from cosmetics, bottles, fibers and other plastic related products [1]. Their size varies a lot as well as its composition; however, it is frequently reported that their size is less than 5 mm and usually come from polymeric materials [2]. Microplastics are on everyone’s thoughts and many investigations are focused on trying to solve this problem; including several iGEM Teams. Nonetheless, there’s an issue that isn’t being disused enough: Endocrine Disruptive Chemicals or EDCs.
Endocrine Disrupting Chemicals (EDCs) are compounds that mimic certain hormones and interfere with body signaling [3]. EDCs are pollutants that come from a variety of sources and are found almost everywhere. They are a whole group of compounds that usually come from the degradation of microplastics and processes related to plastic bottles manufacturing [4]. We are as exposed to them as we are to microplastics; it has been reported that in bottled water there’s a substantial amount of EDCs. For some brands of bottled water, some researchers found a concentration of up to 1990 ng/L of EDCs like antimony [5]. Even though this may not seem like much, we have to remember that these compounds have the potential to bioaccumulate [6]. They have lasting effects on the organism and the ecosystem; for us, they may damage our body or produce troubling diseases such as anomalies in the reproductive systems of both men and women; neurological and learning disorders; problems with fertility; metabolic disorders; obesity and diabetes; cardiovascular problems; and even some types of cancer [3]. In the environment, these chemicals affect animal species that are constantly exposed to them; specially several aquatic species which suffer their toxic effects greatly. The lack of regulations in Mexico and other parts of the world towards these compounds is astounding, given the health and environmental implications they pose. We were mostly concerned that in Mexico, there are no laws that talk about a permitted level of EDCs in drinkable water. Since we have seen that plastic bottles are a primary source of EDCs, it was quite shocking to find out that regulatory agencies aren’t as concerned about this issue as we are. Mainly, we focused on the Norma Oficial Mexicana (NOM or Official Mexican Norm) to check this fact and found nothing on NOM.201-SSA1-2015 “Sanitary specifications of products and services. Water and ice for human consumption”; NOM-127-SSA1-1994 “Environmental health, water for human use and consumption”; and NOM -003-ECOL-1997 “Pollutants in wastewater treatment for public service reuse”.
Currently, there aren’t any methods with the needed quality to detect EDCs in an efficient manner. Most methods are either too expensive or not reliable enough. The most reliable way to detect EDCs is through analytic methods that involve expensive equipment in a laboratory such as mass-based analysis processes like mass spectrometry [7]. However, it is quite obvious that there’s still a need for a faster, reliable and inexpensive way to measure these compounds in situ. In response to this requirement, some researchers have developed sensors that can detect the presence of EDCs through different methods such as the production of biosensors. Nevertheless, they have a few limitations which include their lack of standardization, high sensitivity towards interference and difficulty of production [8], not to mention that they may be expensive. The aim of our project? To create a biosensor that has the desirable characteristics we have discussed: a reasonable price so that it can be widely used; reliable results that give the exact concentration of EDCs in a sample of bottled water; specificity towards any EDC; and the ability to detect compounds in a fast way that doesn’t require any other lab equipment.
Our project:
As stated before, there are a few problems with biosensors. They are very sensitive towards interference and they can get really expensive. There have been researchers that have proposed the use of the Human Estrogen Receptor 1 (hER⍺, ESR1) and its interaction with other proteins to detect these chemicals and measuring them using a piezoelectric sensor [9]. Other sensors proposed use a Quartz Crystal Microbalance (QCM) with part of the ESR1 protein to detect small quantities of estrogenic substances [10]. We got inspired by this research and began the development of our own biosensor which has several characteristics that make it unique.
We designed a biosensor for the detection of Endocrine Disruptive Compounds (EDCs) in samples of bottled water. This biosensor will work through the immobilization of hER⍺ protein receptor on a quartz (the QCM), which is part of a piezoelectric sensor. The protein will capture these chemicals, while the piezoelectric sensor will sense the change of mass through a change of the natural resonance of the quartz. This signal will be received and interpreted by a circuit of our own design and will give us information about the concentration of EDCs on the sample of bottled water. To get an idea of how the protein will be connected to the QCM and how it will work, we recommend checking Figure 1. out.
To meet this objective, we modified a version of the Human Estrogen Receptor hER⍺ to capture EDCs and detect them through its immobilization in a Quartz Crystal Microbalance. We made a prototype designed to measure EDC concentrations in samples of bottled water (Figure 2).
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