LEAD NEWS electron and free it up to participate in conduction, is essential in determining whether a material will be useful in making solar cells or light-emitting diodes (LEDs), or for generating useable fuel. Transition metal oxides exhibit multiple absorption bands, however their many properties –such as the dynamics of photoexcited carriers and subsequent photocatalytic activity – are still not completely understood by the scientific community. Jiming Bao plans to use his most recent Welch award to study the physical and chemical properties of transition metal oxides, specifically cobalt oxides.
properties and fundamental truths and clarified many questions.” As a material scientist, Bao is eager to advance scientific knowledge by better understanding the basic fundamental properties of cobalt oxides and their range of applications. “This is very active energy material. It’s being used in lithium ion batteries,” he said. “We want to use cobalt oxides to convert solar energy into chemical fuel to produce hydrogen, hydrocarbon and even ammonia.”
Cobalt oxides are really active catalysts and used for many chemical reactions, Bao said. Because cobalt has magnetic properties, it is very hard to predict and measure the band structure of cobalt oxides and has led to polarized debates about its bandgap efficacy and conflicting reports.
Debora Rodrigues
“Bandgap is the fundamental property of any semiconductor,” Bao said. “It’s important to understand the physical properties of cobalt oxides because they are related to the chemical properties.”
Debora Rodrigues is using her Welch Award to study the impact of nanoparticles used as antibiotic drug delivery systems in the human body and find a way to fight off antibiotic-resistant bacteria.
For example, he said, “If the bandgap is higher, we can use it to split water using light. If too low, then it can’t be used to split water and generate hydrogen.”
According to the World Health Organization (WHO), “antibiotic resistance is one of the biggest threats to global health, food security and development today.” A growing number of infections – such pneumonia, tuberculosis, gonorrhea and salmonellosis – are becoming harder to treat as antibiotics become less effective.
His research team plans to use transient optical absorption technique and steadystate photoconductivity to probe the relaxation of electrons and holes from conduction band to d states in cobalt oxide nanoparticles and thin films at different temperatures. The photocatalytic activities will be investigated using photoelectrochemical technology and a new type of solar water splitting using water vapor at elevated temperatures. Bao appreciates the Welch Foundation for supporting his research. “Initially I thought this would be a short project, but it has turned out to be a long-term one,” he said. “Continued support is important because along the way we have discovered new
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PARAMETERS Fall 2019
Associate Professor Project Title: Plant-based Antibiotic Nanocarriers Investigation in the Simultaneous Reduction of Pathogen Mutation Rates and Intestinal Infections in Humans. Amount: $195,000
The solution may lie in nanotechnology, which has the potential to revolutionize drug delivery. While it isn’t a new concept, a lot of questions and challenges still need to be addressed. The idea of using nanoparticles as antibiotic delivery systems has been proposed to develop more effective antibiotic therapies and reduce the emergence of antibiotic resistance. It’s thought that nanoparticles can target microorganisms at the site of the infection and so can be used at infected areas for a fast remedy
thereby reducing chances of antibiotic resistance to develop. In addition, because drugs delivered by nanoparticles are more targeted and can be released slowly over long periods of time, this delivery method could potentially decrease the amount of oral drugs a patient has to ingest as well as reduce the length of time a patient must continue taking those drugs. Aside from these benefits, at present little is known about the effects of nanoparticles to either reduce or exacerbate the development of antibiotic resistance. Since antibiotics are typically delivered orally, the characteristics of nanoparticles as they travel through the human digestive system must be understood to ensure that the nanomaterials behave as intended. Rodrigues plans to use novel plant-based carbohydrates (lignin) and poly(lactic-coglycolic) acid nanoparticles loaded with ciprofloxacin antibiotics in a simulated human digestive system bioreactor. The research project will focus on a) correlating drug release rates in different parts of the gastrointestinal (GI) tract with their physical and chemical properties; b) comparing nanoparticles' effects on the emergence of antibiotic resistance in two gut pathogenic microorganisms; and c) investigating their efficiency in preventing infection by the two gut pathogenic microorganisms in human intestinal cells. “We want to determine whether slow released drugs can induce or reduce the emergence of antibiotic-resistant bacteria,” Rodrigues said. “The idea is to reduce the use of antibiotics over time and reduce the emergence of antibiotic-resistant bacteria.” WHO links antibiotic resistance to longer hospital stays, higher medical costs and increased mortality.