Introduction: Reducing the bacterial load of fabrics and textiles is an effective approach to reduce the number of infections, whether in hospital patients, soldiers, or first responders. Injuries can become life-threatening if individuals become infected with bacteria present in the environment [1]. To address this problem, synthetic and natural fibers utilized in hospital furnishings, as well as garments for hospital staff, combat personnel and paramedics were modified using Quaternary Ammonium Compound Dendrimers (QAC-Ds) a robust antibacterial chemical finish. The QAC-Ds have been developed by CCL Biomedical, Inc [2]. The effectiveness of this finish was tested qualitatively as well as quantitatively.
Materials and Methods: Four fabrics were used in this study. 100% cotton, 100% polyester, 100% Nomex 6, and 50/50 nylon/cotton. All fabrics were scoured, rinsed and dried prior to treatment with QAC-Ds. Samples were laundered in a Laundr-O-meter using a commercially available laundry detergent, ATTITUDE.
Control samples of untreated fabric (scoured and washed only), treated samples, and samples after 5 laundry cycles, for all four samples were examined using surface analytical techniques. SEM imaging was used to determine any physical changes in each fabric as a result of applying the antibacterial finish. ToF-SIMS analysis was performed to look for specific amine ions that would indicate the presence of QAC-Ds on the surfaces of fabrics after application of the finish, the degree to which the finish covered the surface, and whether the finish persisted after laundering. Samples of each fabric were challenged with bacteria, followed by neutralization and incubation, to determine antimicrobial efficacy.
Results: The SEM imaging for four fabric samples (Figure 1) clearly shows that depositing QAC-Ds on fiber surfaces does not cause any noticeable degradation of the fibers. Furthermore, bridging of the fibers did not occur indicating that important functional and aesthetic qualities of the fabric were retained.
The four fabric samples were analyzed for total ion intensity for amine compounds present, as shown in Figure 2. The resulting images of the four fabrics shown below for ToF-SIMS demonstrates that the amine compounds were not neutralized, nor washed away, and were present even after laundering.
QAC-D treated fabrics showed antimicrobial action against Gram positive and Gram negative bacteria in challenge tests.
Discussion: Time of Flight Secondary Ion Mass Spectroscopy (TOF-SIMS) showed that the QAC-D coating was applied uniformly on all of the four textile substrates, and was persistent and thorough. The cotton and 50/50 nylon cotton fabrics showed higher binding compared with polyester and Nomex (R) fabrics. It was found that the finish performance was not removed by laundering and was consistent on all four fabrics.
Conclusions: From the surface analyses of four finished fabrics with QAC-Ds it can be concluded that the potential finish treatment applied uniformly and consistently on all the textile fibers studied. The fabric finish was also shown to be durable to laundering. QAC-D treated fabrics showed antimicrobial action against Gram positive and Gram negative bacteria, indicating that the QAC-D technology has the potential to complement existing infection control methods in critical environments.
US Army Medical Material Research Command Contract W81XWH-13-C-0047
References:
[1] Mérens, Audrey, et al. "Prevention of combat-related infections: Antimicrobial therapy in battlefield and barrier measures in French military medical treatment facilities." Travel medicine and infectious disease 12.4 (2014): 318-329
[2] Lamba-Kohli, Nina "Generation of Antimicrobial Surfaces using Dendrimer Biocides". U.S. Patent 8,790,672, Issued Jul 29th, 2014