The natural form of the DNA that carries genetic information in living organisms resembles a set of standard “Lego” blocks that we buy from the store and contains specific pieces and colors, each representing a building block unit.
But what if DNA was synthesized in the laboratory by determining the sequence and structure of the building units (nucleotides) in a way that serves a specific function? This would be similar to designing Lego pieces in a dedicated workshop, where one can choose the color, shape, and size for each cube and create a unique set different from those found in stores. This is the philosophy of “synthetic DNA,” which Chinese scientists have designed to achieve the functions of seawater desalination and uranium extraction.
In the study published in the journal “Science Advances,” the researchers detailed their new method of desalination, with the additional function of extracting uranium, through several steps:
First: Sequence Design
DNA consists of “nucleotides,” and each “nucleotide” consists of a sugar molecule and a phosphate group, and one of four nitrogenous bases: adenine, thymine, cytosine, or guanine. The sequence of these bases along the DNA strand carries genetic information. In synthetic DNA, researchers can process and engineer these sequences to achieve specific functions, such as binding to specific minerals or facilitating certain chemical processes. Therefore, the first step in this work was to describe the sequence of the specific DNA necessary for the required function.
Second: Chemical Synthesis
Using chemical reactions, scientists built DNA strands atom by atom, and through specialized machines and detectors, they added nucleotide building units in the correct order according to the designed sequence.
Third: Purification
The composite DNA is purified to remove any impurities or unwanted secondary products from the chemical structure.
Fourth: Verification
Afterward, the composite DNA is verified to ensure it matches the intended sequence, using different techniques such as DNA sequencing.
Fifth: Embedding in Hydrogel
Once the synthetic DNA is ready, it is embedded in a hydrogel material to become part of a hydrogel system designed to efficiently vaporize water when exposed to solar energy.
Sixth: Reinforcement with Graphene Oxide
Graphene oxide (known for its excellent light-absorbing properties) is introduced into the DNA-enhanced hydrogel, enhancing its ability to absorb solar energy, making the water vaporization process more efficient.
Seventh: Selective Mineral Extraction
During water evaporation, the DNA-enhanced hydrogel exhibits the ability, when designed with the DNA enzyme specific to “uranyl,” to extract minerals such as uranium selectively from seawater.
The “uranyl” DNA enzyme is a type of stimulative DNA that shows a specific affinity for “uranyl ions,” a common form of uranium found in seawater. This enzyme plays a critical role in uranium extraction because it is designed to have high specificity for selectively capturing “uranyl ions,” even in the presence of other ions in seawater. This specificity is essential for efficient uranium extraction without capturing unwanted substances.
The whole system operates under solar illumination, driving the processes of water vaporization and mineral extraction. Simulations and laboratory experiments revealed that the temperature gradient resulting from solar illumination increases ion transport, enhancing the efficiency of water desalination and mineral extraction overall.
The researchers tested the system’s performance in natural seawater and demonstrated its ability to vaporize water quickly and extract minerals selectively, providing a sustainable solution for seawater desalination.
The system showed a high uranium capture capacity of 5.7 mg/g from natural seawater, thanks to the interfacial ion transport driven by solar energy and high selectivity.
Hankso Liang, an associate professor at the College of Chemistry and Materials Science in China and the lead researcher of the study, stated in a report published by “TechXplore” that their new system could enable easy-to-use devices suitable for treating seawater in the future, a solution that should be expanded due to the increasing scarcity of fresh water, posing a threat to communities due to rapid population and economic growth.
The need for desalinating seawater, representing up to 97% of the total water content on Earth, has emerged to facilitate access to fresh water.
While researchers have developed solar-powered seawater desalination techniques as a promising method for producing seawater without additional energy consumption, Liang asserts that their method is promising because it provides, in addition to desalination, extraction of one of the precious metals, uranium.
To ensure the new method remains cost-effective when implemented on a larger scale is of utmost importance. The cost of synthesizing DNA might be high, and thus, evaluating the economic feasibility of this process on a large scale is essential for the commercial viability of this technology.
Despite recognizing these apparent benefits from the experimental results, challenges must be addressed to transition from the experimental level to implementation:
- Scalability: Ensuring the method’s effectiveness on a larger scale is crucial for practical implementation.
- Cost of DNA Synthesis: The cost of synthesizing DNA and evaluating its economic feasibility on a large scale is important for the commercial viability of this technology.
- Durability and Reusability of DNA Hydrogel: Analyzing the lifespan and reusability of DNA-enhanced hydrogel in seawater desalination processes is vital, as continuous exposure to seawater and sunlight may affect its structural integrity and performance over time.
