Progress 08/15/23 to 08/14/24
Outputs
Target Audience:Scientists, professionals, and technical personals in the nanotech for food preservation and safety research community. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?We have made major effort on providing hands-on laboratory research trainings for students and all team members in a highly interdisciplinary and cross-institutional project environment. The students at graduate and undergraduate levels have benefited significantly from their participation in the project. Especially encouraging has been that one participating graduate student graduated with PhD and took a R&D job in relevant industry and several participating undergraduate students went on to pursue their graduate education, which set up excellent examples for other participating students to look forward to similar opportunities in relevant technical fields. How have the results been disseminated to communities of interest?The research activities in this project have become a critical part of our overall effort in the development of carbon dots and their derived nanotechnology. We have been actively disseminating the results from our effort. The peer-reviewed journal publications acknowledging USDA support via this project are as follows. Liang, W.; Cao, L.; Scorzari, A.; McGrath, H.; Bunker, C. E.; Ren, X.; Wang, P.; Yang, L.; Sun, Y.-P. "Photoexcited State Properties of N-Ethylcarbazole-Functionalized Carbon Dots in Solution and in PVK Polymer Matrix" Chem. Phys. Lett. 2023, 833, 140964. (10.1016/j.cplett.2023.140964) Dong, X.; Liu, Y.; Adcock, A. F.; Sheriff, K.; Liang, W.; Yang, L.; Sun, Y.-P. "Carbon-TiO2 Hybrid Quantum Dots for Photocatalytic Inactivation of Gram-Positive and Gram-Negative Bacteria" Int. J. Mol. Sci. 2024, 25, 2196. (10.3390/ijms25042196) Liang, W.; Sheriff, K.; Singh, B.; Qian, H.; Dumra, S.; Collins, J.; Yang, L.; Sun, Y.-P. "On Carbon "Replacing" the Core in Classical Core/ZnS Quantum Dots" General Chem. 2024, 10 (1-2), 240001. (10.21127/yaoyigc20240001) What do you plan to do during the next reporting period to accomplish the goals?We have had a successful start of our project, which is clearly on the right track, so we will continue and expand our progress in the performance of the project tasks. In the next reporting period, we will still emphasize more on the tasks in Aim 1 and some tasks in Aim 2, but also initiate explorations on other project tasks, including those in Aim 3. We will disseminate as much as possible the results from our project to the nanotech for food preservation and safety research community through peer-reviewed publications and conference presentations. Of equal importance is our continuing focus on providing our graduate and undergraduate students with excellent trainings in the related research areas.
Impacts
What was accomplished under these goals?
In the year-1 effort, we have successfully put together collaborative project teams at both partner institutions, with the teams composed of graduate students, research scientist, and undergraduate researchers. Our focus has been on project tasks for mostly Aim 1 and also Aim 2. The significant progress made in the performance of the project tasks is highlighted as follows. 1. Significant Progress in Food-Safe Carbon Dots Platform. Carbon dots (CDots) are classically defined as small carbon nanoparticles (CNPs) with effective surface passivation, which has been accomplished more successfully via the CNPs' surface functionalization with organic molecules. For food related applications of CDots, the use of food-safe organic molecules for the functionalization is obviously required or preferred. We have previously found and demonstrated that CDots with the small diamine molecule 2,2'-(ethylenedioxy)bis(ethylamine) (EDA) for the surface functionalization, thus EDA-CDots, are effective in the inactivation of bacterial pathogens, including multidrug-resistant ones. Molecular structure- and property-wise similar to EDA is the amino molecule diethylenetriamine (DETA), whose food-safe nature is reflected by its being on the FDA list of acceptable food additives, thus selected in this project for the functionalization of CNPs for DETA-CDots. We have made significant progress in the synthetic effort on DETA-CDots for the aim to have their antibacterial performance catch that of the more established EDA-CDots. The available results from antibacterial evaluations of DETA-CDots are very promising. For example, one tested sample of DETA-CDots at the concentration of 100 microgram nano-carbon (in the core CNPs of the CDots) per mL coupled with 1 hour of visible light exposure could kill all (>7 logs) Listeria monocytogenes (10403s) cells. We are pursuing further improvement in the synthesis of DETA-CDots for their being established as a benchmark food-safe CDots platform to be used in Aim 2 and Aim 3 tasks. 2. Dot Samples Tailored to Specific Project Needs. On the other CDots platform selected for this project, PEI-CDots (PEI = polyethylenimine oligomers), which is more established due to our previously more extensive investigations, our effort has been on the more efficient preparation/production of dot samples for the anticipated needs in other project tasks. In terms of the objectives of this project, the primary configuration with the use of CDots is for the dots to be on surface, loosely defined in such a way that the dots should be sufficiently exposed for interactions with bacteria species in the fluid phase but there must be no leaching into the fluid at all. For such a dual requirement, acceptable or even advantageous dot samples are those in which classical CDots or CDots-equivalent/like entities are dispersed in and crosslinked with some organic species, namely some specific versions of the "nano-carbon/organic hybrids" as we have defined in our recent publications. Such dot samples can be prepared efficiently by the thermal carbonization of selected organic precursors, including mixtures of PEI with citric acid (PEI/CA) for dot samples that are comparable with PEI-CDots for the specific needs in this project. In our year-1 effort, we have extensively and systematically investigated the carbonization of PEI/CA in different compositions and with varying processing conditions. Our results show that the formed nano-carbons (CNPs-like entities in the dot samples) are sourced not only from the carbonization of CA (commonly considered as being more readily carbonized) but also from PEI significantly, among other interesting and unexpected findings. Antibacterial evaluations of the dot samples have also been performed, with the results suggesting effective inactivation of several bacterial species. A manuscript reporting the synthesis, characterization, properties (including antibacterial results) of the dot samples is in the advanced stage of preparation. More interesting and potentially very significant and valuable are the results from the same carbonization synthesis with added preexisting CNPs, namely PEI/(CA+CNPs) as precursors for thermal carbonization processing. The dot samples thus prepared could have much higher nano-carbon contents, valuable in terms of high efficiency in the sample preparation and also other desirable sample properties that are not available in the absence of the added CNPs and in the classically synthesized PEI-CDots. Comprehensive characterizations of the dot samples prepared with different PEI/(CA+CNPs) precursor mixtures under various processing conditions are being pursued, so are the antibacterial evaluations of the selected dot samples. 3. Valuable Exploration of Antibacterial Coating Formulations. On the development of CDots-derived coating formulations with selected polymers as binders, which is a major project task for Aim 2, we have used aqueous compatible polymers poly(propionylethylenimine) (PPEI) and poly(vinyl alcohol) (PVA) to disperse PEI-CDots. PVA is particularly valuable for its characteristic property of no solubility in ambient water but soluble in hot water (85 C, for example) yet without precipitation in the subsequent cooling back to ambient temperature, thus ideally suited for coatings/films that are prepared in aqueous media and still remain intact for uses in aqueous media. As an important initial step, we have prepared thick gel-like formulations of PEI-CDots dispersed in polymeric PPEI and PVA, denoted as PPEI/PEI-CDots and PVA/PEI-CDots gels, respectively. We have used the gels in microplate wells for antibacterial tests (against Listeria monocytogenes as target, for example), from which the results have shown highly effective killing of the bacteria cells under visible light exposure conditions comparable with those used in similar evaluations of PEI-CDots in solution. However, interestingly and rather puzzlingly has been the observation of the similar killing without the light exposure, suggesting other antibacterial mechanisms at work. We are expanding the antibacterial evaluations for improved understandings.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2024
Citation:
Dong, X.; Liu, Y.; Adcock, A. F.; Sheriff, K.; Liang, W.; Yang, L.; Sun, Y.-P. CarbonTiO2 Hybrid Quantum Dots for Photocatalytic Inactivation of Gram-Positive and Gram-Negative Bacteria Int. J. Mol. Sci. 2024, 25, 2196. (10.3390/ijms25042196)
- Type:
Journal Articles
Status:
Published
Year Published:
2024
Citation:
Liang, W.; Sheriff, K.; Singh, B.; Qian, H.; Dumra, S.; Collins, J.; Yang, L.; Sun, Y.-P. On Carbon Replacing the Core in Classical Core/ZnS Quantum Dots General Chem. 2024, 10 (1-2), 240001. (10.21127/yaoyigc20240001)
- Type:
Journal Articles
Status:
Published
Year Published:
2023
Citation:
Liang, W.; Cao, L.; Scorzari, A.; McGrath, H.; Bunker, C. E.; Ren, X.; Wang, P.; Yang, L.; Sun, Y.-P. Photoexcited State Properties of N-Ethylcarbazole-Functionalized Carbon Dots in Solution and in PVK Polymer Matrix Chem. Phys. Lett. 2023, 833, 140964. (10.1016/j.cplett.2023.140964)
|