Source: UNIVERSITY OF NEW HAMPSHIRE submitted to
SUPER-REPELLENT ANTIMICROBIAL COATINGS TO ENSURE FOOD SAFETY
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
AFRI COMPETITIVE GRANT
Reporting Frequency
Annual
Accession No.
0223818
Grant No.
2011-67022-20036
Project No.
NHR-2010-03451
Proposal No.
2010-03451
Multistate No.
(N/A)
Program Code
A1511
Project Start Date
Dec 1, 2010
Project End Date
Nov 30, 2013
Grant Year
2011
Project Director
Ming, W.
Recipient Organization
UNIVERSITY OF NEW HAMPSHIRE
(N/A)
DURHAM,NH 03824
Performing Department
(N/A)
Non Technical Summary
Unsafe food and food poisoning due to insufficient protection from pathogenic bacteria results in human suffering from illness and tremendous financial repercussions. Numerous outbreaks in the U.S. were due to contaminated food processing facility. Therefore, it is of extreme importance to prevent the accumulation of pathogenic bacteria inside food processing facilities. Our objective is to develop super-repellent antimicrobial nanostructured coatings for food processing facilities (both food contact and non-contact surfaces) to eliminate a major external source of bacterial infection for food. The super-repellent antimicrobial coatings, which are topographically structured to mimic the lotus leaf surface (i.e., dual-scale structure), will combine two mechanisms of eliminating bacteria into one system: repelling (due to super-repellency against both water and oil) and killing (due to covalently bonded quaternary ammonium groups at the coating surface). The innovative antimicrobial coatings can be applied to food processing facilities and peripheral surfaces (drains, floors, storage tanks, apparel, etc.), and have the potential to greatly reduce bacterial attachment and biofilm formation, thus reducing foodborne pathogens. Moreover, the technology to be developed may also find applications in healthcare settings, personal hygiene industry, biomedical industry, and other high-touch, high risk environments, making significant contributions to a better and safer society.
Animal Health Component
(N/A)
Research Effort Categories
Basic
60%
Applied
40%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
7124010200050%
7125399200050%
Knowledge Area
712 - Protect Food from Contamination by Pathogenic Microorganisms, Parasites, and Naturally Occurring Toxins;

Subject Of Investigation
5399 - Structures, facilities, and equipment, general/other; 4010 - Bacteria;

Field Of Science
2000 - Chemistry;
Goals / Objectives
Our objectives are to eliminate bacteria common in processing/packaging facilities by applying a super-repellent antimicrobial coating on various surfaces (including equipment, interior wall, ceiling, drain, storage tank, etc.) in the facility. The nanostructured coating can effectively repel most of the bacteria, and kill the rest that manage to adhere to the surfaces in the facility to ensure food safety. Our goals are two-fold: (1) to synthesize and characterize super-repellent antimicrobial polymeric coatings; (2) to examine the antimicrobial properties and establish structure/property relationships for these coatings. In our targeted super-repellent antimicrobial coatings, the antimicrobial moieties (quaternary ammonium groups) will be covalently bonded to the polymer matrix, preventing them from leaching out into food. The outputs of this project include: (A) Activities: (1) Preparation and characterization of smooth antimicrobial coatings; (2) Preparation and characterization of nanostructured, super-repellent antimicrobial coatings; (3) Preparation and characterization of mechanically robust, super-repellent antimicrobial coatings; (4) Antimicrobial tests, with the aim at understanding the mechanism of antimicrobial actions (killing and/or repelling of bacteria); (5) Mentoring a graduate student. (B) Events: Reporting project findings, when appropriate, in relevant conferences and symposia. (C) Products: Potential patent applications; Peer-reviewed journal publications.
Project Methods
Our planned research will be divided into the following main tasks: (1) Smooth antimicrobial coatings. We will prepare smooth antimicrobial polymer coatings by using a surface segregation strategy to examine whether covalently bonded antimicrobial species still have antimicrobial properties. Via this approach, the antimicrobial moieties such as quaternary ammonium compounds (QAC), will be segregated at the coating surface (it is unnecessary to have antimicrobial groups in the bulk of a coating) and, in the meantime, chemically bonded to the cross-linked polymer network. The key in our approach is that the QAC groups will be connected to a fluorinated or silicone (PDMS) chain (low surface-energy species), which provides the driving force for the QAC-containing moiety to segregate at the coating surface. (2) Super-repellent antimicrobial nanostructured coatings. To eliminate bacteria in a more effective way, i.e. combining repelling bacteria with killing bacteria, we aim at preparing super-repellent antimicrobial nanostructured coatings with a raspberry-like surface topography. The raspberry-like nanosized structure is expected to reduce significantly the anchoring area for microbes, making it very difficult for them to attach. In addition, the presence of perfluorinated QAC groups will make sure that those tenacious bacteria, which manage to adhere to the surface, are killed upon contact with the super-repellent surface. Therefore, the super-repellent antimicrobial coatings will allow both contact-killing and maximum repelling of bacteria. (3) Antimicrobial tests. Initial events in microbial adhesion will likely play a role in the final biofilm structure. Our goal is to stop the biofilm process before it can take anchor with our super-repellent coatings. For tenacious bacteria, which overcome the super-repellent barrier, we further aim to demonstrate bactericidal properties against two common foodborne sources of infection, E. coli and Salmonella. Exposure of coated surfaces to these bacterial solutions will allow us to determine the minimum inhibitory content (MIC) of the antimicrobial on the surface. The following samples will be primarily used for antimicrobial tests: smooth antimicrobial coatings (biocidal assessment); super-repellent coatings with no QAC, compared to smooth fluorinated coatings (biostatic assessment: inhibit ability to attach); and super-repellent antimicrobial coatings (biocidal assessment: kill tenacious bacteria). To verify whether the antimicrobial action is due to the combination of a bactericidal effect and a repellent effect, live/dead cell analysis using flow cytometry will be performed after bringing the test strains in contact with the active coating. We will run antimicrobial leaching tests to confirm that the covalently attached antimicrobial groups remain bound to the nanostructured coatings. We will also examine the durability of these coatings.

Progress 12/01/10 to 11/30/13

Outputs
Target Audience:Our smooth antimicrobial polyurethane coatings containing a long perfluoroalkyl (C8F17) ammonium compound (RfQAC) have shown very strong antimicrobial activities against both Gram-positive and Gram-negative type of bacteria even at very low concentrations (0.5 wt%). These coatings may find useful applications in food processing facility, healthcare settings, personal hygiene industry, and other high-touch, high risk environments. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?A graduate student was trained and gained experience in preparing and characterizing antimicrobial polymer coating. How have the results been disseminated to communities of interest?The results obtained from this project during the first year were included in 2 peer-reviewed journal papers. In addtion, 1 oral presentation was given in an ACS meeting. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? The accomplishment listed below covered the period of Dec. 1st, 2010 through Nov. 30th, 2011, after which the project was transferred from University of New Hampshire to Georgia Southern University due to the move of the PI (Ming). A final report under a different project no. (GEOW-2011-06299) was submitted in 2014. 1. We designed and synthesized reactive, perfluoroalkyl quaternary ammonium compounds (RfQAC). 2. RfQAC compounds were covalently incorporated into conventional polyurethane (PU) coatings. 3. Surface and antimicrobial properties of RfQAC-containing PU coatings have been examined, and demonstrated total kill against both Gram-positive and Gram-negative bacteria. 4. We also introduced quaternary ammonium-based, reactive ionic liquids to polyurethane coatings, and characterized their surface and antimicrobial properties. 5. Some results have been described in two published papers in Progress in Organic Coatings. 6. The PI attended the IPCG Polymer Colloids conference in June 2011, in which functional colloidal particles were shown to be used for biomedical/healthcare applications.

Publications

  • Type: Journal Articles Status: Published Year Published: 2011 Citation: Yagci, M. B.; Bolca, S.; Heuts, J. P. A.; Ming, W., de With, G. Self-Stratifying Antimicrobial Polyurethane Coatings, Progress in Organic Coatings 2011, 72, 305-314.
  • Type: Journal Articles Status: Published Year Published: 2011 Citation: Yagci, M. B.; Bolca, S.; Heuts, J. P. A.; Ming, W., de With, G. Antimicrobial Polyurethane Coatings Based on Ionic Liquid Quaternary Ammonium Compounds, Progress in Organic Coatings 2011, 72, 343-347.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Zhao, J.; Ming, W. Anti-bioadhesion on hierarchically structured, superhydrophobic surfaces, 245th American Chemical Society (ACS) National Meeting, New Orleans, LA, Apr. 2013.


Progress 12/01/11 to 11/30/12

Outputs
OUTPUTS: The following outputs have been achieved during the reporting period: 1. We have successfully prepared hierarchically structured, superhydrophobic surfaces, with single-, dual-, and triple-scale roughness via a layer-by-layer (LbL) particle deposition approach. 2. These superhydrophobic surfaces, especially the triple-scale structured surface, exhibited significantly reduced protein adsorption, and could completely suppress platelet adhesion. 3. We have synthesized reactive, perfluoroalkyl quaternary ammonium compounds (RfQAC); the reactive groups include acrylic double bond, hydroxyl and siloxane, which will allow us to covalently bond the RfQACs to structured coatings. 4. We also started preparing super-repellent, antimicrobial fabric. PARTICIPANTS: A post-doc, Dr. Jie Zhao, joined the project in Dec. 2011. TARGET AUDIENCES: The super-repellent, hierarchically structured coatings we have made via layer-by-layer particle deposition, which can reduce protein adsorption and suppress completely platelet adhesion (bacterial adhesion will be tested soon) may find applications in food processing facility, healthcare settings, personal hygiene industry, and other high-touch, high risk environments. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Following our successful synthesis of reactive perfluoroalkyl quaternary ammonium compounds (RfQAC), which were covalently incorporated into polyurethane coatings, leading to very effective smooth, antimicrobial coatings, we turned our attention to prepare hierarchically structured coatings aiming at obtaining super-repellent coatings that would resist bacterial adhesion. The hierarchically structured coatings we have made via layer-by-layer particle deposition have demonstrated excellent anti-bioadhesion property (significantly reduced protein adsorption and no platelet adhesion at all). So, even without grafting RfQAC compounds onto the structured coatings, these coatings may become an attractive platform for a range of biomedical applications through synergistically tuning surface chemistry and topography. We also made RfQAC compounds with other reactive groups such as acrylic double bond and siloxane, which will allow us to covalently bond the RfQACs to various substrates, such as coatings, fabric, and even paper. This will certainly broaden the application areas of our strategy that are pertinent to food safety.

Publications

  • Zhao, J., Ming, W. Anti-bioadhesion on Hierarchically Structured, Superhydrophobic Surfaces, Abstract submitted to ACS Spring Meeting 2013 (New Orleans).


Progress 12/01/10 to 11/30/11

Outputs
OUTPUTS: The output listed here covers the period of Dec. 1st, 2010 through Aug. 11th, 2011 when the project was temporarily terminated due to the move of the PI (Ming) from University of New Hampshire to Georgia Southern University. Transfer of the grant from UNH to Georgia Southern has been requested. 1. We designed and synthesized reactive, perfluoroalkyl quaternary ammonium compounds (RfQAC). 2. RfQAC compounds were covalently incorporated into conventional polyurethane (PU) coatings. 3. Surface and antimicrobial properties of RfQAC-containing PU coatings have been examined. 4. We also introduced quaternary ammonium-based, reactive ionic liquids to polyurethane coatings, and characterized their surface and antimicrobial properties. 5. Some results have been described in two manuscripts, which are now accepted for publication in Progress in Organic Coatings. 6. The PI attended the IPCG Polymer Colloids conference in June 2011, in which functional colloidal particles were shown to be used for biomedical/healthcare applications. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Our smooth antimicrobial polyurethane coatings containing a long perfluoroalkyl (C8F17) ammonium compound (RfQAC) have shown very strong antimicrobial activities against both Gram-positive and Gram-negative type of bacteria even at very low concentrations (0.5 wt%). These coatings may find useful applications in food processing facility, healthcare settings, personal hygiene industry, and other high-touch, high risk environments. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
We have designed and successfully synthesized two new perfluoroalkyl quaternary ammonium compounds (RfQAC), and via their covalent incorporation into polyurethane network we successfully made smooth antimicrobial coatings. The RfQAC with a long perfluoroalkyl chain (C8F17-) was shown to strongly segregate at the PU coating surface, as demonstrated by dynamic contact angle and X-ray photoelectron spectroscopy (XPS) measurements, leading to very strong antimicrobial activities against both Gram-positive and Gram-negative type of bacteria even at very low concentrations (0.5 wt%). This is a significant development and a major advantage compared to previously reported bulk antimicrobial coatings in which large amounts of antimicrobial species are required to obtain satisfactory antimicrobial performance. In addition, RfQAC is chemically bonded to PU coatings in our approach, so there will be no concern over undesired leaching of antimicrobial species. These smooth antimicrobial coatings alone may find useful applications in food processing facility, healthcare settings, personal hygiene industry, and other high-touch, high risk environments. Our next steps are going to focus on making RfQAC-containing, super-repellent coatings, which hopefully can not only kill bacteria but also effectively repel them. Based on the results achieved so far and our expertise in controlling surface topography, we believe the project is moving toward the right direction.

Publications

  • Yagci, M. B.; Bolca, S.; Heuts, J. P. A.; Ming, W., and de With, G. (2011) Self-Stratifying Antimicrobial Polyurethane Coatings. Progress in Organic Coatings (in press, available online).
  • Yagci, M. B.; Bolca, S.; Heuts, J. P. A.; Ming, W., de With, G. (2011) Antimicrobial Polyurethane Coatings Based on Ionic Liquid Quaternary Ammonium Compounds. Progress in Organic Coatings (in press, available online).