Photo caption: Optical image of living microlenses. Engineered microbes focus light that pass through a thin layer of glass that forms on their surface.  Courtesy of Lynn Sidor, Meyer Lab, University of Rochester.

CU Boulder’s   played a key role in studying tiny bioglass lenses that were designed to form on the surface of engineered microbes, a scientific breakthrough that could pave the way for groundbreaking imaging technologies in both medical and commercial applications.

The project, led by the University of Rochester and published in Proceedings of the National Academy of Sciences, was inspired by the enzymes secreted by sea sponges that help them grow glass-like silica shells. The shells are lightweight, durable and enable the sea sponges to thrive in harsh marine environments.

“By engineering microbes to display these same enzymes, our collaborators were able to form glass on the cell surface, which turned the cells into living microlenses,” said Wil Srubar, a coauthor of the paper and professor of Civil, Environmental and Architectural Engineering and the Materials Science and Engineering Program. “This is a terrific example of how learning and applying nature’s design principles can enable the production of advanced materials.”

Using imaging and X-ray techniques, CU Boulder researchers analyzed the silica, also known as “bioglass,” and quantified the amount surrounding different bacterial strains. The CU Boulder researchers demonstrated that bacteria engineered to form bioglass spheres contained significantly higher silica levels than non-engineered strains. Combined with optics data, the results confirmed that bacteria could be bioengineered to create bioglass microlenses with excellent light-focusing properties.

Microlenses are very small lenses that are only a few micrometers in size—about the size of a single human cell and designed to capture and focus or manipulate light into intense beams at a microscopic scale.  Because of their small size, microlenses are typically difficult to create, requiring complex, expensive machinery and extreme temperatures or pressures to shape them accurately and achieve the desired optical effects.

The small size of the bacterial microlenses makes them ideal for creating high-resolution image sensors, particularly biomedical imaging, allowing sharper visualization of subcellular features like protein complexes. In materials science, these microlenses can capture detailed images of nanoscale materials and structures. In diagnostics, they provide clearer imaging of microscopic pathogens like viruses and bacteria, leading to more accurate identification and analysis.

The University of Rochester contributed to this report.

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Forbes Magazine is featuring groundbreaking research conducted by faculty members at CU Boulder in the field of eco-friendly concrete.

Cement is a significant contributor to carbon emissions, responsible for about eight percent of global output.

Prometheus Materials, a company co-founded by Wil Srubar and Mija Hubler, associate professors in the Department of Civil, Environmental and Architectural Engineering, is commercializing an algae-based form of concrete developed from research at CU Boulder.

This new concrete that can be grown in a laboratory and has significant potential to drastically reduce environmental pollution caused by construction activities around the globe.

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The article, "" was published in the August issue of  . Authors include Civil, Environmental, and Architectural Engineering researchers Yao Wang, a post doctoral research associate working in Mija Hubler's lab; Associate Professor Mija Hubler;  Associate Professor Wil V. Srubar III; Shane Frazier, a graduate student in the Materials Science and Engineering Program, working in the  under Srubar;  and Linfei Li, a postdoctoral researcher in Hubler's lab, and others.

Their research explores the possibility of storing carbon in permanent building elements to reduce our carbon footprint.

The project involved research integrating products from two start-ups which spun out of CU Boulder —Prometheus Materials, a company spun out of the CEAE labs of Srubar, Hubler and Sherri Cook; and Jeff Cameron in Biochemistry at the College of Arts and Sciences; and Minus Materials, which uses microalgae to produce CO2-storing biominerals for the cement and concrete industry.

The article discusses testing a system designed to achieve overall carbon negativity. The system comprises a concrete slab supporting a wall constructed using concrete masonry units (CMUs). The concrete slab was made of alkali-activated cement containing algae-derived carbon-storing, biogenic limestone. The CMUs contain biomineralizing microalgae and a proprietary hydrogel binder as cement replacement.

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Each time Mija Hubler drives through Denver, she notices bridges patched with concrete and thinks about how these structures might fail.

Hubler, an associate professor in CU Boulder’s Department of Civil, Environmental and Architectural Engineering, envisions a future where concrete cracks are repaired deep within to prevent such failures. She and her team of CU Boulder researchers and partners are developing technology that infuses concrete with self-repair capabilities found in living organisms. 

“Bridges are just patched again and again,” Hubler says. “My dream is to extend the structures’ lifetime by integrating this technology into new and aging construction.”

The project, "Reinforced Concrete Repair by an Evolving Visualized Internal Vascular Ecosystem (RC-REVIVE)" research team, has landed a $10 million grant from the Defense Advanced Research Projects Agency (DARPA) Biorestoration of Aged Concrete (BRACE) program, which draws inspiration from networks of filamentous fungi and human vascular systems. 

The idea is that networks of cracks in concrete can naturally provide a pathway to facilitate internal healing, similar to the veins in human bodies. Creating a biological network within a structure will allow the team to introduce nutrients and organisms for concrete self-repair.

Led by Hubler, the research team includes Associate Professor Wil Srubar, Associate Teaching Professor Chris Senseney and Assistant Professor Srikanth Madabhushi as well as four researchers from Drexel University and North Carolina State University.

Leveraging cracked networks to extend a concrete structure’s lifespan has never been done before, Hubler says. The team’s approach has the potential to transform the maintenance and durability of concrete structures, reducing long-term repair costs, she adds.

The project’s immediate goal is to enhance the longevity of Department of Defense structures and airfield pavements. If successful, the project will not only prevent new damage, but also shorten repair time, reduce maintenance costs and extend the life of infrastructure. 

The 4.5-year research effort consists of a strategic track, focusing on long-term solutions for large, heavy structures such as missile silos and naval piers, and a tactical track for improving rapid airfield damage repair.

Susan Glairon sat down with principal investigator Associate Professor Mija Hubler to find out more about the project.                                                                                                                                                                                                                                
Why is this project important to you?
I have been studying the long term deterioration of large reinforced concrete structures since I was a graduate student. Reinforced concrete structures not only cost dollars, but also lives, because they fall apart much earlier than expected.

This project combines my work developing new living materials for structural applications with my extensive background in studying the deterioration of existing reinforced concrete structures. It’s an exciting project because it merges those two areas.

What’s different about this project?
Compared to other projects I've worked on that utilized bio approaches for engineering applications, this project specifically focuses on vascularization. We draw inspiration from the idea that concrete crack networks naturally provide a pathway, similar to the veins in our bodies. By creating a biological pathway within the structure, we can introduce nutrients and organisms, enabling self-repair capabilities. 

The bacteria will repair cracks through mineral deposition.

Why is the proposed method a better way to repair concrete?
Currently we repair concrete after the damage has reached the surface, but typically the damage begins subsurface. Patching the broken surface is not actually repairing the system. Our method addresses the damage from within, allowing more effective and lasting repairs.

Why are you looking at a bio solution?
Researchers across all disciplines of engineering are realizing the importance of collaborations with biology and bioengineering. In this project, we're exploring a combination of organisms that are either available in the wild or engineered to fulfill a specific purpose. 

How do  these organisms survive?
It depends on which organism. For a photosynthetic organism, light may be sufficient. For non-photosynthetic organisms, additional stimulants can be incorporated into the material to encourage them to grow or respond. You can also promote the growth of certain organisms with an electric field through a current applied to the system. 

How many years might an organism be able to make repairs?
It depends on the organism. We are putting these organisms in an environment they don't like to live in. Concrete is not an ideal habitat for any organism, so we plan to engineer coating and other technologies to help the organisms live longer. Additionally, we might need to periodically check on the vascular system and provide it with additional nutrients to support the organism’s existence. Our approach shifts the focus from yearly surface repairs to monitoring the health of the vascular network.

Is the research focused on repairing existing concrete or is it to prevent cracks in new concrete as well?
The first two years of the project primarily focuses on developing a bio-based repair technique. After this initial stage, the team will explore two potential applications. One application involves the underground repair of aged, reinforced concrete, including filling existing cracks, and mitigating corrosion from rebars. The other application focuses on repairing extensively damaged airfields, which is different because when an airfield is damaged, it results in regions of missing material. So our technology will need to be incorporated into a new repair material that resembles fresh concrete. We have design metrics aimed at determining the capacity of repaired sections to accommodate aircraft landings. CU Boulder is leading both applications. 

How will you assess the longevity of internal repairs?
We will assess the mechanical and chemical condition of the concrete along with the effectiveness of the biological repair system. That information will be used by our modeling experts to develop a numerical model that predicts the structure’s lifetime.

Will this technology be used just for military applications, or will the research be used to improve civilian roads and bridges?
While DARPA projects are often inspired by military needs, most technologies initially developed for one purpose may be used for other purposes as well. Although the project intends to address an array of challenges faced by the military, the resulting product could be utilized for civilian infrastructure as well.  

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Associate Professor Wil Srubar was honored with the American Ceramics Society (ACerS) Cements Division Early Career Award on June 15 at the   meeting. The meeting took place at Columbia University in New York.

Srubar has been recognized for his research in a variety of venues recently.  He was recently honored with a nomination for the 2023 Pritzker Emerging Environmental Genius Award and was named a Schmidt Science Polymath. He was also named to the . Previously, he was selected as the BioEnvironmental Polymer Society Outstanding Young Scientist in 2021 and won a prestigious National Science Foundation CAREER award in 2020. To date, his laboratory has received more than $12 million in sponsored research funding through the U.S. National Science Foundation, Air Force Research Laboratories, ARPA-E and DARPA’s Biological Technologies Office.

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