FEBRUARY 2023 Southwest Retort

Vol. 75(6) February 2023

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2022 DFW Section Officers

Chair: Mihaela C. Stefan

Chair-elect: Rajani Srinivasan

Past Chair: Trey Putnam

Treasurer: Martha Gilchrist

Secretary: Violeta Vega Gomez

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From the ACS Press Room

Voice-activated system for hands-free, safer DNA handling

“Function of the Speech Recognition of the Smartphone to Automatically Operate a Portable Sample Pretreatment Microfluidic System”

ACS Sensors

Smart voice assistants are a popular way for people to get quick answers or play their favorite music. That same technology could make the laboratory safer for scientists and technicians who handle potentially infectious samples. Researchers in ACS Sensors now report a small, voice-activated device that can extract and pretreat bacterial DNA, helping protect those on the front lines of disease outbreaks. The system could also help scientists with disabilities conduct studies more easily.

Scientists working with samples containing pathogens need to work with the smallest amounts possible to avoid accidental infection. And for highly contagious bacterial diseases, on-site sample analysis is ideal for rapid diagnoses. In addition, scientists who have visual or other physical impairments may find it difficult to operate complex instruments, especially those designed for tiny volumes. Hands-free devices that operate quickly through voice commands could make this process easier and safer. So, Tae Seok Seo and colleagues wanted to combine a speech recognition app with a miniaturized extraction system to do just that.

The researchers first made a microfluidic chip with multiple chambers linked together

by six 3-way solenoid valves, which were operated by a micro-controller connected to a Bluetooth module. The palm-sized device weighed only 11 ounces and could be powered by a portable battery or a 5V smartphone charger. Then, using existing speech recognition software, the team customized a smartphone app to listen for specific voice commands. Here’s how it works:

• Once a user says one of the operation commands out loud, the app wirelessly sends an initiation signal to the micro-controller.

• After receiving the signal, the microcontroller automatically starts a series of steps, including sample loading, washing and releasing the purified DNA into a collection

Continued on page 15

This small, voice-activated device extracts and pretreats bacterial DNA and could make the laboratory safer for scientists and technicians.

From the ACS Press Room

Using CRISPR to detect cancer biomarkers

“Highly Effective Detection of Exosomal miRNAs In Plasma Using LiposomeMediated Transfection CRISPR/Cas13a

ACS Sensors

Most cancer diagnostic techniques rely on uncomfortable and invasive procedures, such as biopsies, endoscopies or mammograms. Blood samples could be a less unpleasant option, though only a few forms of the disease can currently be diagnosed this way. But now, researchers reporting in ACS Sensors have developed an easy-to-use method that can detect small amounts of cancerrelated molecules in exosomes in plasma and effectively distinguish between malignant and benign samples.

Exosomes are small vesicles that pinch off from a host cell, carrying cargo, such as nucleic acids, lipids and proteins, inside. This means that they provide a window into the condition of the cell they originated from. Accordingly, the unique intracellular environment of cancerous cells will be reflected in their exosomes through biomarkers such as micro RNAs (miRNAs). These are very small nucleic acids, only a few nucleotides in length, that regulate protein expression in cells and can become dysregulated in tumors. Therefore, it’s possible that a blood test could someday detect cancerous cells simply by targeting these exosomal miRNAs.

But quantifying miRNAs has been difficult because they are present at very low levels in exosomes, requiring laborious processes that

can introduce contamination and report unreliable results. So, some researchers have analyzed RNA and proteins in vesicles with the gene-editing tool CRISPR. But Hua Gao, Kaixiang Zhang and colleagues wanted to develop a way to detect the small numbers of cancer-related exosomal miRNAs using a different CRISPR system with a unique RNase activity that was sensitive, reliable and effective.

To create the detection method, the team designed a CRISPR/Cas13a system to cut apart a fluorophore and quencher-labeled reporter molecule, then packed it into a liposome essentially a manufactured version of an exosome. When the two types of compartments fused together, the CRISPR cargo would then interact with the exosomal genetic material. If the target miRNA sequence was present, the Cas13a protein became activated and cut apart the reporter molecule, producing a fluorescent signal. In these experiments, the team targeted miRNA-21, which is involved in the development of several diseases, including breast cancer. The method successfully detected this miRNA within a mixture of similar sequences with high sensitivity. In other experiments, the researchers tested the method on a group of ex-

angellodeco/Shutterstock.com

”

A blood test could someday diagnose cancers by analyzing the genetic material in exosomes.

Recent advances in candy and sweet snack research From the ACS Press Room

Valentine’s Day is just around the corner, which means it’s time to buy chocolates and candies for that someone special. Or perhaps, you prefer healthier treats, in the form of fresh or dried fruits. Below are some recent papers published in ACS journals that investigate the complex way chocolate melts in the mouth, how Turkish delights are delightfully chewy and the best way to dry sweet cherries. Reporters can request free access to these papers by emailing newsroom@acs.org.

Valorization of Sweet Cherries (Prunus avium) Using Different Drying Methods for Obtaining a Healthy Dried Product

ACS Food Science & Technology

Jan. 20, 2023

Chile is a major grower of sweet cherries, yet despite producing more than 445,000 tons of the fruit last year, around 17% failed to meet export standards. One way to add value to discarded cherries is to dry them. The researchers investigated several drying methods and found that drying them in the sun, the most common method, was detrimental to these compounds’antioxidant potential. The best method was convective drying at around 150 F.

Insights into the Multiscale Lubrication Mechanism of Edible Phase Change Materials

ACS Applied Materials & Interfaces

Jan. 12, 2023

The silky-smooth way a piece of chocolate melts in your mouth is not very well understood, scientifically speaking. To figure it out, these researchers built their own realistic tongue and novel tribomicroscopy technique. They found that fats in chocolate form tiny emulsion droplets that coalesce into a layer of film, leading to that “coating” feeling on the tongue. This knowledge could help create lower-calorie dark chocolates that still have good mouthfeel.

Effect of Different Syrup

Types on Turkish Delights (Lokum): A TDNMR Relaxometry Study

ACS Food Science & Technology

Nov. 30, 2022

Turkish delights are chewy candies cut into delicate cubes and dusted with powdered sugar. Alternatives sometimes use corn syrups or sweeteners instead of sugar, but do they hold up to the original? Here, scientists used time-domain NMR spectroscopy to investigate the crystallinity in candies made using sugar, corn syrup or allulose. They found that the low-calorie allulose candies were too soft and had difficulty holding their shape, whereas the corn syrup candies were firm and had an appealing color.

From the ACS Press Room

Another promising step toward non-hormonal male contraceptives

“Screening through Lead Optimization of High Affinity, Allosteric Cyclin-dependent Kinase 2 (CDK2) Inhibitors as Male Contraceptives that Reduce Sperm Counts in Mice”

Journal of Medicinal Chemistry

\Despite birth control existing for decades, almost none of the options specifically target sperm cells. Researchers are now developing approaches that target testosterone or otherwise interrupt the sperm’s ability to fertilize an egg, yet these may not work for everyone. But now, researchers publishing in ACS’ Journal of Medicinal Chemistry have identified a new candidate molecule that could become an effective non-hormonal contraceptive for many people who produce sperm.

Previously, Gunda I. Georg and colleagues investigated non-hormonal contraceptive options, as approaches targeting testosterone produced unwanted side effects. They developed a drug targeted at a specific vitaminA receptor and found that it worked as a highly effective contraceptive with no side effects. But numerous proteins are involved in forming sperm, and exploring multiple options would help increase the likelihood of one making it to human clinical trials and eventually onto the market.

Another set of proteins involved in the cell cycle are the cyclin-dependent kinases, or CDKs, which play a role in sperm cell production and tumor development. Mice without the CDK2 receptor are sterile, so a drug

that targets this protein could serve as an effective contraceptive. It also has potential as a cancer therapeutic because inhibiting the enzyme slowed tumor growth in previous studies. However, CDK2 has a very similar shape to other enzymes in its family, and currently available inhibitors tend to produce undesirable offtarget ef-

WHITE MARKERS/Shutterstock.com

fects by accidentally binding the others as well. So, Georg and her team wanted to develop a drug that could selectively inhibit CDK2 to serve as another contraceptive option.

The team previously discovered an unknown binding site in CDK2 and a commercially available dye molecule that successfully bound to it. Using the dye as a starting point, the researched screened tens of thousands of different compounds in their current work to find ones that also bound the pocket well. They narrowed the list down to just three, picking one to further optimize. The best version, named EF-4-177, demonstrated a long half-life and good diffusion into the tes-

Continued on page 16

A new molecule is another promising candidate for a non-hormonal male birth control that targets sperm cells (illustrated here).

From the ACS Press Room

ACS ES&T Water

Parents often give their children useful advice: Wash your hands, cover your cough and put the toilet lid down before flushing. Now, researchers reporting in ACS ES&T Water spit out thousands of virus particles from infected waste. However, the team says this amount of virus won’t always lead to an infection, and urine-diverting toilets can reduce a person’s exposure compared to traditional systems.

It’s a well-known fact that flushing a toilet sprays out tiny droplets of water, as well as urine and feces, into the air. These particles land on nearby surfaces or get breathed in by people nearby. But if it’s an infected person’s waste that’s flushed, contagious pathogens, such as noroviruses, adenoviruses and human polyomaviruses, could also be ejected into the air. Most commodes in the U.S. are of the traditional mix flush type, and they empty one large water-filled compartment. Another type of toilet is called a urine-diverting system and has two compartments: one that collects urine in the front and another that removes excrement through the back waterfilled compartment. Viruses in urine would be removed through the urine-diversion section, but of those that end up in the water, it’s not clear how much get sprayed out. So,

Krista Wigginton, Lucinda Li and colleagues wanted to compare the levels of viruses emitted from flushing the two types of systems to estimate their potential for spreading disease.

To simulate the effects of an average excretion event from a sick person, the researchers added solutions with 10 billion surrogate viruses into the

Adapted from ACS EST Water 2023, DOI: 10.1021/ acsestwater.2c00521

water of traditional and urine-diverting toilets in a university restroom. They used two bacteriophages: MS2, which is similar to norovirus, and T3, which stood in for adenovirus and polyomavirus. Then the team simply covered the bowls with plastic film and flushed. Material from the films was recovered and analyzed to see how much MS2 and T3 splashed onto it.

The results showed that less than 1% of the virus surrogates added to the toilets sprayed out. And when protein was added to the water, simulating the proteins found in urine, the traditional commode expelled tens of times more MS2 and T3 than the urine-

Continued on page 16

Urine-diverting toilets expel fewer virus particles than traditional toilets, study suggests

“Virus Emissions from Toilet Flushing: Comparing Urine-Diverting to Mix Flush Toilets”

Although each flush of a urine-diverting toilet (shown here) spits out millions of virus particles, they emit less than a traditional system.

Generating electricity from tacky tape From the ACS Press Room

“Power Generation by a Double-Sided Tape” ACS Omega

Along with bitterly cold temperatures, winter usually brings dry air and the occasional zap of static electricity. Those shocks might be annoying, but researchers are working to harness that otherwise wasted energy with triboelectric nanogenerators (TENGs) to power everyday devices. Now, in ACS Omega, a team describes an easy way to manufacture these tiny generators out of materials as simple as double-sided store-bought tape that pack in higher energy densities than previously reported versions.

TENGs can transform mechanical energy into electrical energy through the triboelectric effect, which is a form of static electricity But instead of that static turning into a shock, these nanogenerators send it through a circuit to power a device, such as an LED. Though based on simple principles, many TENG devices are complicated and expensive to make and only produce a few watts of power. Previous research has shown that simplified TENGs can be made with a combination of tape, plastic and met-

al, but their low power densities have prevented them from being used in practical applications. So, Gang Wang and colleagues wanted to design an uncomplicated, easy-tofabricate TENG that would work as well as more sophisticated designs.

The researchers created a TENG with layers of store-bought double-sided tape and plastic film covered with a thin sheet of aluminum metal. When these two layers were pressed together then disconnected from one another, a small spark formed between them. If more pressure was placed on the layers, they could generate more power. In fact, the TENG was able to produce power densities consistent with that of other, more complicated versions. A double-electrode version of the device could even produce a power density of 169.6 watts per square meter 47% higher than that previously reported for other devices, the researchers say.

In a series of tests, the team put the TENG through its paces. When hooked up to an array of LEDs, the generator could light up over 400 lights simultaneously when someone pressed the layers. Attaching the TENG to the bottom of a shoe could turn on LEDs with the power of a simple step. In addition, the generator could power a laser diode, which could pave the way for use in sensors and light-based electronics. The researchers say that this generator design could help meet the larger power demands for selfpowering electronics with simpler and cheaper materials.

Continued on page 16

This adhesive tape-based nanogenerator can light several hundred LEDs.

Credit: Adapted from ACS Omega, 2022, DOI: 10.1021/acsomega.2c05457

Around the Area

UT Dallas

Dr. A. Dean Sherry, a distinguished scientist and educator who retired in 2022 after 50 years on the faculty of The University of Texas at Dallas, has been named a fellow of the National Academy of Inventors. Dr. Manuel Quevedo-Lopez has opened a new research center to advance semiconductor technology and test electronics in this highly specialized field. The Center for Harsh Environment Semiconductors and Systems (CHESS) addresses a demand for materials and devices that can withstand extreme temperatures, radiation and extreme mechanical conditions. CHESS is the first initiative of UT Dallas’ new North Texas Semiconductor Institute (NTxSI), which aims to accelerate semiconductor innovation, entrepreneurship and workforce development in North Texas.

https://news.utdallas.edu/faculty-staff/sherry -national-academy-of-inventors-2023/ https://news.utdallas.edu/science-technology/ new-esearch-center-semiconductors-2023/

From ACS Press Room Con’t

“Voice Activated System”

Continued from page 5 chamber.

The system currently requires the user to touch the smartphone to start the speech recognition software, but the researchers say that the whole operation could be made entirely hands-free in the future with the addition of virtual assistant software.

In tests, the voice-controlled device extracted DNA from Salmonella Typhimurium, purifying a 10-µL sample with an efficiency of 70% in less than a minute. Although the system had a lower performance than a traditional DNA extraction kit, the researchers say that its voice control, portability and quick automation give it an advantage for convenient and safe bacterial DNAtesting.

The authors acknowledge funding from the Korea Health Technology R&D Project/ Korea Health Industry Development Institute (KHIDI); the Ministry of Health and Welfare of South Korea; and the Engineering Research Center of Excellence Program of the National Research Foundation of Korea.

From the ACS Press Room continued

“Using CRISPR ”

Continued from page 6

osomes from healthy human cells and groups derived from breast cancer cells. The system consistently differentiated the cancer -related exosomes from those derived from healthy cells, showing it could be useful as a cancer diagnostic. The researchers say that this method has the potential to make cancer diagnosis and monitoring quicker and easier by analyzing blood samples.

The authors acknowledge funding from the National Natural Science Foundation of China, the Postdoctoral Science Foundation of China, the Programs for Science & Technology Innovation Talents in Universities of Henan Province, and Outstanding Young Talents in Henan Province.

Male Contraceptives

Continued from page 9

tes of mice.After a 28-day exposure, the animals’sperm counts decreased by about 45%. Additionally, EF-4-117 bound much more strongly to the CDK2 pocket than the dye, making it the highest affinity inhibitor for this site reported to date. The researchers say that this work proves the potential of this inhibitor for future therapeutic applications.

The authors acknowledge funding from the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), the National institute of Health,

the National Institute of General Medical Sciences and the National Cancer Institute.

“Urine-diverting Toilets

Continued from page 12

diverting version. The researchers also calculated the maximum emissions for different viruses from a single flush. For example, they estimated that up to 390 million and 67 million genome copies of norovirus could be emitted from traditional and urinediverting toilets, respectively. These levels are within the range of an infectious dose; however, the researchers state that it’s unlikely a person would be exposed to all of the particles because some would probably evaporate, settle onto surfaces or be inactivated by handwashing. The next step is to determine a person’s risk of contracting these and other diseases from toilet flushing, the researchers say.

The authors acknowledge funding from a University of Michigan Rackham Merit Fellowship, a University of Michigan MCubed grant and the U.S. National Science Foundation

“

Generating Electricity

Continued from page 14

The authors acknowledge funding from the College of Engineering at the University of Alabama in Huntsville and Materials Sciences LLC.

From the Editor

Yes! An in-person Meeting-in-Miniature at Tarleton on April 22! Undergrads, grad students, and postdocs: register for a presentation of your research. Nothing gets you ready for the research world like a stand-up presentation with questions afterwards. In my graduate program at LSU in the biochemistry department, grad students had to register for seminar twice a year and give a seminar. Also, judges are needed for this event, so plan on signing up.

Best press release: generating electricity from sticky tape….what? Gang Wang and colleagues created a TENG (triboelectric nanogenerator) with layers of store-bought double-sided tape and plastic film covered with a thin sheet of aluminum metal. When these two layers were stuck together then disconnected (i.e., pulled apart really fast) a small spark formed between them. More pressure on the layers generated more power.