Recipient Organization
HALOMINE INC.
1411 HANSHAW RD
ITHACA,NY 148502730
Performing Department
(N/A)
Non Technical Summary
Food safety is a priority goal for the USDA NIFA SBIR Program and the food industry for obvious food security, public health, and economic reasons. Hazard Analysis and Critical Control Points (HACCP) systems have been implemented industry wide to manage operational disinfecting and cleaning, but these approaches are not infallible. Technical solutions are needed that can enhance current systems and reduce risk of food-borne illness. Because modular conveyor belts represent the second most prolific contact surface within typical food processing facilities, they pose a significant risk for cross-contamination and are a challenge to effectively clean. In this proposal, Halomine, Inc. presents HaloAdd™, a novel thermoplastic additive for preventing pathogen cross-contamination and biofilms on modular conveyor belt applications using a potent rechargeable antimicrobial plus anti-fouling technology. Our strong value proposition includes broad spectrum activity against pathogens, rechargeable potency, bio-adhesion prevention, safe, durable, and cost effective. Key objectives for the project include: 1) optimization of synthesis parameters to achieve maximum functionality, 2) demonstration of product safety for food contact, and 3) confirmation that polymer material properties are preserved. Once commercialized, HaloAdd technology will leverage a substantial market opportunity and will hold a unique competitive advantage due to its ability to pass the EPA criteria for making supplemental residual antimicrobial claims when used together with chlorine-based disinfectants regularly.
Animal Health Component
50%
Research Effort Categories
Basic
(N/A)
Applied
50%
Developmental
50%
Goals / Objectives
Objectives for the phase I effort were distilled after the completion of a gap analysis by the project team. Three key opportunities were defined.Technical Objective 1: Achieve antimicrobial performance of 3-log reduction in 2 hours per EPA Interim Guidance protocol of adding supplemental residual antimicrobial efficacy while also demonstrating resistance to bio adhesion by optimizing synthesis, HDPE melt-blending parameters, and additive loading levels. Successful completion of this objective will provide a polymer additive recipe capable of achieving potency goals while informing loading concentration requirements in HDPE. Technical Objective 2: Demonstrate that molded HDPE+HaloAdd is stable against leaching and that surface halogen can be recharged. Successful completion of this objective will prove functional feasibility and the initial safety of the technology. Technical Objective 3: Verify that material property (tensile, hardness, and impact strength) of molded polymer are improved or retained within 90% of unmodified material. Successful completion of this objective will demonstrate that additives do not impact material feasibility.
Project Methods
Task 1. Synthesize HA-SBMA copolymers with varying molar concentrations and molecular weights. (in support of Technical Objective 1).HA-SBMA copolymers will be synthesized using free-radical polymerization and with varying molar feed ratios. Molecular weight will be controlled by adjusting initiator concentration and incorporation of a chain transfer agent (CTA). Reaction mixture will then be heated to 65 °C and polymerization was allowed to proceed for 3 hours. Following cool-down and drying, copolymer will be collected as a dry powder and stored in dry conditions. Dried product will be evaluated using Nuclear Magnetic Resonance (NMR), Gel Filtration Column (GPC), and Differential Scanning Calorimetry (DSC) to determine the composition, molecular weight, and the glass transition temperature (Tg) and properties cataloged for task 2.Task 2. Assess impact of copolymer molar ratio, molecular weight, additive concentration, and melt-blending parameters on additive dispersion in HDPE. (in support of Technical Objective 1).Copolymers produced in task 1 will be blended into HPDE pellets (MW ~ 500 kDa) at concentrations (w/w) of 0.5, 2.5, and 5.0% HaloAdd using a HAAKE MiniLab Micro Compounder at different temperatures from 140-180 °C (with 10-ºC interval) between 2-5 mins (with 1-min interval). Then the pellets will then be hot pressed into film at 160 ºC for 2 min using Carver press between Mylar sheets, then cut into 2 cm x 2 cm samples. We will observe the film appearance to determine which formulation and temperature combination creates acceptable outcome using a light microscopy. Acceptable conditions would produce a transparent and clear film with no polymer aggregates inside of the film. Successful blending will also be confirmed by performing X-ray Photoelectron Spectroscopy (XPS) and Elemental Scanning Electron Microscopy (EDX with SEM) at multiple locations on each sample. Qualified film samples will be promoted for further testing.Task 3. Select samples capable of achieving surface chlorine levels >1016 atoms/cm2 (in support of Technical Objective 1).Surface amines of samples promoted from Task 2 will be transformed into N-halamines by chlorination with dilute sodium hypochlorite. Briefly, samples will be immersed in aqueous solution containing 10% (v/v) household bleach (8.25% NaClO) with pH adjusted to 5 plus 0.05 wt% of a non-wetting agent (TX-100). After 60 minutes of mild agitation, samples will be rinsed copiously with water and dried overnight. To assess active surface chlorine, an iodometric titration method will be used.Task 4. Verify antimicrobial efficacy performance of samples selected in Task 3 against a panel of gram-positive and gram-negative bacteria as specified by EPA Interim Guidance (in support of Technical Objective 1).Antimicrobial function ofHaloAdd + HDPEsamples from Task 3 will bedetermined using an antimicrobial testing method developed by EPA: Interim Method for Evaluating the Efficacy of Antimicrobial Surface Coating. Staphylococcus aureus (ATCC #6538) and Pseudomonas aeruginosa (ATCC #15442) will be used as representative strains in this test. Bacterial colonies were enumerated and recorded for biocidal efficacy analysis. The log density of Colony Forming Units (CFU) will be calculated and then mean log density will calculated by average of three carriers in each group and log reduction will be calculated through comparing with control samples. Formulas that meet EPA residual antimicrobial surface requirements of >3 log reduction within 2 hours for both bacteria will be promoted for further testing.Task 5. Assess anti-fouling performance of successful candidates from Task 4; select optimal candidates with lowest additive concentrations that resist protein and bio adhesion (in support of Technical Objective 1).Samples prepared in Task 4 will be tested for protein and bio-adhesion resistance in accordance with published procedures. For protein-fouling, 2 mg/mL fluorescein isothiocyanate-labeled fibrinogen (FITC-fibrinogen) will be put in contact with 1x1 inch2 square sample coupons for 1 h under ambient temperature. Sample coupons will then be dip-rinsed in sterile DI water and inspected immediately under fluorescence microscope. Fouling will be expressed by mean fluorescence strength quantified via ImageJ. Each test will be done in triplicate. For biofouling, overnight culture of Escherichia coli (E. coli, ATCC 25922) will in contact with 2x2 cm2 square sample coupons for 1 h and stained with BacLight LIVE/DEAD staining kit for 30 min. The samples were inspected under fluorescence microscope without any rinsing or cleaning. Adhesion is expressed by the numbers of bacterial cells normalized to the actual size of the field of vision. Bacterial cells were counted via ImageJ. Each test will be done in triplicate.Task 6. Perform migration testing per FDA food contact material migration testing method to assess the safety risk of HaloAdd monomers and impurities leaching into food products (in support of Technical Objective 2).Migration experiments will be conducted following the FDA migration tests for overall and specific migration of chemicals in HaloAdd modified HDPE samples. Each migration test will be conducted in triplicate including blanks/control samples, resulting in total of 100 samples. Specific migration (n=100) will be conducted using non-targeted analysis with liquid chromatography (LC) coupled with mass spectrometry (MS) (orbitrap MS) and targeted analysis with LC-MS/MS triple quadrupole tandem MS. Specific migration tests will be focused on monomers HA and SBMA.Task 7. Confirm rechargeability characteristics of the molded polymer conditions simulating industry-standard cleaning procedures (in support of Technical Objective 2).Alkaline detergents and sodium hypochlorite are widely used in food processing for daily cleaning. To evaluate the stability of the modified HDPE under typical conditions, chlorinated samples will be measured for initial Cl levels, then put in submerged in a solution of chlorine-based disinfectant agent (DiverseyTM Liqu-A-Klor chlorine solution, use concentration at 2,000 and 4,000 ppm) administered per manufacturer's instructions for the equivalent of 100 washing cycles. Samples will then be removed, thoroughly rinsed, and remaining chlorine measured again using iodometric titration. After chlorine quantification, coupons will be rechlorinated with 200 ppm of chlorine for 10 min and titrated for chlorine content. The procedure will be repeated three times for to assess the equivalent of 300 washing cycles. Antimicrobial potency will be verified using the same method described in Task 5 against two organisms.Task 8. Determine the influence of incorporating HaloAdd on HDPE material properties including tensile strength, shore D hardness, and impact strength (in support of Technical Objective 3).Samples selected in Task 5 will be molded and tested in accordance with ASTM specifications D256 and D638 and D2240. Modified HDPE material will successfully meet goal if Young's modulus, yield strength, ultimate strength, impact strength, and hardness are within 90% of unmodified material.