Potential applications of diatoms

[Global] Diatoms are single cell eukaryotic microalgae, which present in nearly every water habitat make them ideal tools for a wide range of applications such as pharmaceutical usage, oil exploration, forensic examination, bioenergy, environmental indication, biosilica pattern generation, toxicity testing and eutrophication of aqueous ecosystems.

Thalassiosira pseudonana
Thalassiosira pseudonana

Diatom as a tool for cancer drug delivery

Many cancer treatments, including chemotherapy remedies, kill cancer cells but also harm healthy cells, causing side effects for patients.

To reduce side effects, methods to deliver drugs to target cancer cells only have been developed. Scientists have had some success in this area by using silica-based nanoparticles, but the production process is expensive, and involves the use of toxic chemicals.

In a study headed by Professor Nico Voelcker, from the Centre for Excellence in Bio-Nano Science and the University of South Australia, diatoms were loaded with nanoparticles of chemotherapy drugs, and injected into mice suffering tumours.

In a study published in Nature Communication, researchers uses silica-rich microalgae known as diatom to substitute expensive artificial silica nanoparticles. The research showed that diatom Thalassiosira pseudonana can be genetically engineered to display antibody binding ability, which allow the diatom to deliver drug-loaded silica-based nanoparticles to target cancer cells. 

Researchers altered the algae so that the silica coatings of the cells were covered with a protein that binds to antibodies.

diatom kill cancer

These antibodies, which make up a large part of the human immune system, then bind to the cancer cells that are attacking the body.

Use of diatom in energy production

Diatoms are a major group of algae, and are among the most common types of phytoplankton. A unique feature of diatom cells is that they are enclosed within a cell wall made of silica (hydrated silicon dioxide) called a frustule.

The deposition of silica by diatoms may also prove to be of utility to nanotechnology. Diatom cells repeatedly and reliably manufacture valves of various shapes and sizes, potentially allowing diatoms to manufacture micro- or nano-scale structures which may be of use in a range of devices, including: optical systems; semiconductor nanolithography; and even vehicles for drug delivery.

With an appropriate artificial selection procedure, diatoms that produce valves of particular shapes and sizes might be evolved for cultivation in chemostat cultures to mass-produce nanoscale components.

Diatoms could be used as a component of solar cells by substituting photosensitive titanium dioxide for the silicon dioxide that diatoms normally use to create their cell walls. Diatom biofuel and diatom solar panels have also been proposed.

It was announced recently that engineers at Oregon State University
Oregon State University super solar panel.

It was announced recently that engineers at Oregon State University (OSU) have discovered a way to fabricate solar cells that may be up to three times as efficient as conventional solar cells. The new diatom based process focuses on producing dye-sensitized solar cells, a type of thin film cell in which photons bounce around inside the cell striking photosensitive dyes, which are mere nanometers in size, to produce electrical charge. The difference with the cells produced using the OSU process is made possible because of the unique natural structure of the diatom shell. The diatom shell, or frustule, consists of two asymmetrical sides with a split between them and contains many naturally occurring nanometer sized pores throughout.

The insertion of other metal oxide materials such as titanium or germanium dioxide into the nanostructure of the diatom frustule could potentially be utilized to fabricate new dye-sensitized solar cells, nanostructured battery electrodes, and electroluminescent display devices.

(a) Optical microscopy images of Coscinodiscus sp. (b) Simplified 3D structure of the unit cell of diatom frustule based on experimental results. Thickness of the three layers: Cribellum t1 = 50 nm, Cribrum t2 = 300 nm, Internal Plate t3 = 1000 nm, (c) Left: top view of cribellum, the lattice constant p1 = 200 nm and the hole size d1 = 50 nm. Middle: top view of cribrum, the lattice constant p2 = 400 nm and the hole size d2 = 250 nm. Right: top view of internal plate, the lattice constant p3 = 2 μm and the hole size d3 = 1.3 μm.
(a) Optical microscopy images of Coscinodiscus sp. (b) Simplified 3D structure of the unit cell of diatom frustule based on experimental results. Thickness of the three layers: Cribellum t1 = 50 nm, Cribrum t2 = 300 nm, Internal Plate t3 = 1000 nm, (c) Left: top view of cribellum, the lattice constant p1 = 200 nm and the hole size d1 = 50 nm. Middle: top view of cribrum, the lattice constant p2 = 400 nm and the hole size d2 = 250 nm. Right: top view of internal plate, the lattice constant p3 = 2 μm and the hole size d3 = 1.3 μm. (Xiangfan Chen et al., 2015)

When can we begin to produce solar cells using algal shells and nanotechnology? Gabriella Tranell, an Norwegian University of Science and Technology researcher, is careful not to predict, but she has faith in nature’s ingenious solutions.

“In ten years, solar cells will be far different than today, both in design and materials. I think we will be making solar cells that are copies of biological structures. We need to think differently if we want to produce clean renewable energy that is also economic. Solar panels are now designed so that they move smoothly to track the Sun as it goes across the sky, from east to west. But maybe we should be looking at the way leaves are arranged on trees: they are not symmetrically oriented towards the light at any time, but are turned in slightly different directions.”

“We see that it is more and more of interest to imitate nature, to learn how nature has made structures that are functional. Inspired by nature!” And then, Gabriella Tranell smiles like the Sun.

Diatoms as environmental indicators

In general, diatom species are very particular about the water chemistry in which they live. In particular, species have distinct ranges of pH and salinity where they will grow.

Dr. Marina Potapova collects diatoms from Cole Run, a headwater stream in northcentral Pennsylvania.
Dr. Marina Potapova collects diatoms from Cole Run, a headwater stream in northcentral Pennsylvania.

Diatoms also have ranges and tolerances for other environmental variables, including nutrient concentration, suspended sediment, flow regime, elevation, and different types of human disturbance. As a result, diatoms are used extensively in environmental assessment and monitoring.

Furthermore, because the silica cell walls do not decompose, diatoms in marine and lake sediments can be used to interpret conditions in the past. Paleoecology is a field that utilizes both living and subfossil diatom valves that are preserved in marine and freshwater sediments. Scientists use living cells to understand the environmental factors that determine the modern presence and abundance. Then, scientists can apply the knowledge of species preferences in modern conditions to interpret the diatom species from the past, and the historical conditions that those species imply.

 

Exclusively reported by Algae World News

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