Performing Department
(N/A)
Non Technical Summary
This partnership project is a collaborative effort between Clemson University and North Carolina Central University. The project aims to develop a novel and effective antimicrobial packaging technology, which is based on the coating of packaging films with food-safe paint-like formulations containing small carbon particles-derived materials denoted as carbon dots (CDots). These specifically designed CDots will be produced using food-grade ingredients, and will be formulated to modify the surfaces of plastic films commonly found in commercial food packages. Such modified food packing films with exposure to visible or ambient light will be capable of hindering the growth of food spoilage microbials and also pathogenic bacteria, thus extending the shelf life of the packaged food items and preventing pathogenic food poisoning. The project team will assess and optimize the design and production of CDots and their derived formulations for the desired antibacterial functions, evaluate the effectiveness of the modified packaging films against selected food spoilage bacteria and foodborne pathogens, and validate the feasibility of the technology with a specifically constructed antimicrobial "self-cleaning" poultry package resembling those commonly found in grocery stores. The successful outcomes from the project are expected to lead to a new food packaging technology and associated protocols applicable to addressing the major challenges in food spoilage and contaminations in food packages, and to address fundamental and technical issues that are critical to the eventual implementation of the technology.
Animal Health Component
0%
Research Effort Categories
Basic
80%
Applied
10%
Developmental
10%
Goals / Objectives
The long-term goals of the project include:1. To materialize the "self-cleaning" strategy for food-safe CDots modified food packages capable of the visible light-driven "self-cleaning" to address the major issues/challenges associated with food spoilage microbials and related pathogenic contaminations.2. To explore and address both fundamental and technical issues/challenges that are critical to the eventual implementation of the antimicrobial "self-cleaning" food packaging technology, with also efforts on developing industrial partnerships to leverage their experience and technical capabilities for practical applications of the technology.The specific aims of the project include:Aim 1. Food-Safe CDots for the Visible/Ambient Light-Activated Function against Spoilage and Pathogenic Bacteria.Aim 2.Modification of Surfaces with CDots Formulations for Antimicrobial "Self-Cleaning" under Visible/Ambient Light. Aim 3.Toward Eventual Implementation of the Antimicrobial "Self-Cleaning" Packaging Technology with Simulated Device-Level Validation.
Project Methods
For Aim 1:Food-safe CDots will be prepared by the surface functionalization of small carbon particles with food-safe organic molecules diethylenetriamine (DETA) and polyethylene (PEI) oligomers. The obtained DETA-CDots and PEI-CDots samples will be characterized by using established instrumental techniques and protocols, and evaluated for their light-activated antibacterial function. The attachment of the CDots to selected polymers via radical addition reactions will also be pursued.The antibacterial function of the proposed CDots will be assessed using the pathogenic spoilage bacteria including C. perfringens and Bacillus cereus, and representative strains of foodborne pathogen Listeria monocytogenes, as models for the antibacterial evaluations. Two methods will be used to assessantibacterial effect of each CDots sample: 1) Viable cell reduction by each CDots sample with light activation in a dose-dependent manner, at various treatment conditions, will be determined in reference to appropriate controls; 2) Minimal inhibitory concentration (MICs) are considered as the "gold standard" to determine the efficacy of antimicrobial agents to certain bacteria species. We will use the standard 2-fold serial dilution method to determine CDots' MICs to each of the bacteria.For Aim 2:The CDots-derived coating formulations will be prepared with selected polymers as binders. The formulations will be characterized by using various instrumental techniques, and evaluated for their light-activated antimicrobial activities. The selected winning formulations will be used to modify plastic films, including polyethylene and poly(ethylene-co-vinylalcohol) films. The modified films will be characterized for quality control and improvements.For the evaluation of the antibacterial properties of the modified film surfaces, the same spoilage bacteria and Listeria strains as above will be used as targets in the evaluations. We will formalize the protocols by following the three major international standards on the assessment of antimicrobial activity on surfaces (Japan standard JIS Z2801:2010, European standard ISO 22196:2011, and newly proposed US standards [80,81]), with some modifications as necessary. Generally, a standardized inoculum of ~6x105 cells/mL is applied to the CDots-modified surfaces and otherwise identical surfaces without CDots as controls. The bacteria are incubated for a desired period (5 min to 24 h) and exposed to the selected visible light sources of different defined intensities and with other variables, including the exposure time, distance, and angle in various combinations, as well as multiple variables of the designed surfaces, including CDots loading on the surfaces, thickness of the CDot-polymer layer, persistence of the antibacterial activity, and shelf-life of the CDots-modified surfaces. After the treatment, survival of bacteria on the surfaces will be assessed by eluting bacteria from the CDots-modified surface by PBS and collecting for enumeration of viable cells by standard surface plating. Viable cell reductions by the treatments are used for the measure of antibacterial performance of the designed "self-cleaning" surfaces at given conditions.For Aim 3:The stability of the CDots-modified surfaces will be evaluated by examining the potential leaching of CDots from the surface over time periods up to several months, with varying conditions including moisture, neat water and solutions of varying pH values, various aqueous media with organic substances to mimic those found in fresh meat and poultry packages, etc., at different temperatures.Cytotoxicity of the CDots-modified film coupons will be evaluated by using the established MTT cell viability assay using cell lines of intestinal, hepatic, and vascular endothelial origins.A miniaturized package will be constructed with a small soaking pad (~5 x 4 cm, for example) to hold real meat/poultry samples for evaluations. The soaking pad will be coated with CDots-derived antimicrobial formulations for visible light-driven activities against spoilage/pathogenic bacteria in the soaked water in the modified pad. As controls for the active "device" will be those in the same configuration but to be kept in the dark or without any CDots modification. We will spike the active and control devices with the selected bacterial strains for light/dark and CDots/blank comparisons in the bacterial growth at room temperature and 4 Cover 14 days.