(38h) Incorporation of Reactive Silver-Tricalcium Phosphate Nanoparticles Into Polyamide (Nylon) Allows Preparation of Self-Sterilizing Fibers | AIChE

(38h) Incorporation of Reactive Silver-Tricalcium Phosphate Nanoparticles Into Polyamide (Nylon) Allows Preparation of Self-Sterilizing Fibers

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Polymer fibers are ever-present in our world. In 2002 the global production of manufactured fibers was 36 million metric tons: Fiberglass pads build modern cars, polyesters form textile goods and polyamide fibers are used as bristles for brooms and toothbrushes. Since bacterial contamination may cause diseases or even death, it is desirable to provide fibers with antibacterial properties.

The present contribution investigates the ability of silver-tricalcium phosphate (Ag/TCP) nanoparticles to build a reactive antibacterial system in polyamide fibers. These nanoparticles consist of 20-50 nm sized carriers, based on calcium phosphate, a major nutrient of bacteria. This bait is spiked with 1-2 nm silver particles. In the presence of growing bacteria, the tricalcium phosphate (TCP) carrier particles are biodegraded and trigger the release of the antibacterial silver [1]. Applying silver in this complex form allows significant increases in antibacterial efficiency due to a larger contact area [2] and triggered release of the active silver exclusively when TCP is consumed by bacteria [3]. This reduces the required amount of silver if compared to non-reactive systems.

Ag/TCP nanoparticles (1.3 wt% silver) were produced by flame spray synthesis [4] and subsequently extruded with polyamide 6 yielding a composite polymer with 2 wt% filler. Following melt-spinning of the extrudates resulted in fibers (~110 µm thick; containing 260 ppm silver) for antibacterial testing. Fibers were contaminated with the clinically relevant strains Escherichia coli or Streptococcus sanguinis, respectively. The reactive fibers demonstrated significantly reduced plate count within 24 hours if compared to pure polyamide reference fibers (several orders of magnitude). More specifically, compared to pure polymer bristles, the number of colony forming units was reduced by 99.999 % with E. coli and 99.6 % with S. sanguinis.

Figure: Antibacterial activity of silver nanoparticles incorporated into a reactive system with tricalcium phosphate nanoparticles extruded with polyamide 6 and comparison to pure polymer. Temporal evolution of the total bacteria number during the course of the day after contamination with E. coli or S. sanguinis is shown. (Dark: pure PA6 fibers; Light: Ag/TCP fibers).

References: 1. Q.L. Feng, J. Wu, G.Q. Chen, F.Z. Cui, T.N. Kim, and J.O. Kim, J. Biomed. Mater. Res., 52, 4 (2000). 2. I. Sondi and B. Salopek-Sondi, J. Colloid Interface Sci., 275, 1 (2004). 3. S. Loher, O.D. Schneider, T. Maienfisch, S. Bokorny, and W.J. Stark, Small, 4, 6 (2008). 4. W.J. Stark, S. Pratsinis, M. Maciejewski, S.F. Loher, and A. Baiker, WO2005087660-A1 (2005).