Project Description

The Problem?

With the entrance into 21st century, enormous new techniques and innovations are expanding rapidly. At the same time, people are demanding a higher-quality life. Nanotechnology, has emerged since 1980s and developed rapidly in several decades, are widely adopted by medicine, energy, transportation, food safety, environmental sciences, and many other fields due to its promising benefits to society [1]. An avanced application of nanotechnology is the wastewater treatment. In the water environment, nanomaterials are often more attractive to water and oil molecules, so they are adopted in wastewater treatment to remove pollutants and to clean up oil spills at sea. However, the after used nanomaterials can not be completely removed from the water environment and might be aggregate and accumulate locally to cause long-term effects on local ecosystems.

Fig 1. The applications of nanotechnology [9]

Moreover, many studies have revealed that nanoparticles actually bring considerable amount of severe adverse effects to the ecosystem, as well as human health. AgNPs that enter animal body by orally exposure can be distributed to most organs [3,4] and can cause both acute and chronic adverse effects on organismal, cellular, and molecular level, including profound delays and lethality of development and longevity by inducing ROS-mediated stress responses [2].

Fig 2. Proposed schematic diagram of pathways of NPs into the environment. (Image retrieved from Batley et al., 2011) [10]

In order to study the adverse physiological effects potentially brought by nanoparticles, scientists have carried out huge amount of researches on animal models. A previous study stated that mice treated with lower dose of titanium oxide (TiO2) nanoparticles in long-term has resulted in ovarian damage in adult mice and is accompanied by alterations in the expression of genes associated with estrogen and progesterone synthesis and metabolism [7]. Besides, researchers have found the toxicity effects of nanoparticles on steroidogenensis, including neuroendocrine dysfunction, steroid hormone imbalance, and the unusual placenta barrier and embryonic development [8]. Therefore, based on these negative results performed in animal models, obviously that there is an urgent need to address this question of likely exposure and the relative impact of different types and sizes of nanoparticles, particularly in the context of more vulnerable populations, such as pregnant women and their fetuses.

Fig 3. Nanoparticles penetrate developing follicles and interfere with the maturation of the oocytes. (Image retrieved from Cong-Cong, Hou and Jun-Quan Zhu, 2017) [11]

Fig 4. Conventional methods of wastewater treatment. (Retrieved from Wikimedia Commons) [12]

However, it is not capable to clean up most of the ultrafine particles due to the smaller pore size than nanoparticles. Besides, nanoparticles in wastewater possess cytotoxicity towards microorganisms in bioactive sludge could decrease the pollutants removal efficiency of sludge in wastewater treatment. Not only that, the construction and operation of the membrane technique is very costly and unaffordable for developing countries and even third-world countries [5]. Therefore, it is an urgent need to develop a novel and effective method to remove the nanomaterials from wastewater system due to the increasing reveals of its potential harms to ecosystem and human body.

The NPs removal challenge in local and worldwide

We contacted the DSPA (Direcção dos Serviços de Protecção Ambiental DSPA, The official environmental protection bureau in Macau ) and got a chance to visit the wastewater treatment plants in the Transborder Industrial Zone of Macau. From this visit, we learned that currently, we don’t have the regular supervision systems targeting nanoparticle pollution and only the basic wastewater treatment techniques were adopted with unclear effects on nanoparticle clearance. The core technology applied in this plant is ATLANTIS® submerged Membrane Bio-Reactor(MBR) technology from Belgium company WaterLeu.

Our solution

Since nanopollution in water system has become an unneglectable issue facing global ecosystem and threating human health, our team was motivated to apply synthetic biology into society to establish an effective nanoparticles removing model named Self-Activating Nanoparticles Collecting E.coli (SANCE). This is achieved by engineering a controllable nanoparticle collector microorganism via bacteria aggregation in the process of wastewater treatment. Additionally, via a magnetic field, we would achieve a goal of microorganism immobilization to eventually collect the E.coli-Nanoparticle complexes in wastewater. Its capability in collecting nanoparticles would potentially be applied in wastewater treatment plant to remove harmful nanopollutants, such as heavy metal mercury, phosphate, total nitrogen, ammonia nitrogen, and organic compounds.

Fig 5. Our project general idea: Self-Activating Nanoparticle Collector E.coli (SANCE)

The success of our project would provide a cheap and renewable nanopollutant removal model that can be applied in the wastewater treatment of many countries, especially developing countries and even third-world countries, helping people there to free from potential adverse health effects brought by nanopollutants.

Fig 6. Our project is inspired by the sticky protein Mefp-5 on the foot of mussel.

Inspiration

Our project is inspired by a literature, “Preparation of Sticky Escherichia coli through Surface Display of an Adhesive Catecholamine Moiety” published by a Korean research team in 2014. Based on the idea of engineering a bacteria with sticky feature on its cell surface, we would like to focus on the structure and characteristics of the sticky domain of the engineered E. coli and enhance its effectiveness and efficiency in capturing nanoparticles by transforming the E.coli with a variety of plasmid constructs. With the improved version of E. coli, it is expected to be capable in capturing those pollutants mentioned above which are currently a noteworthy issue in wastewater treatment. 

Reference