Jun Ishibashi¹, Megumi Kasashima¹, Makoto Nakamura², Seiji Tokino², Hideaki Suzuki³, Tomio Nagano³

¹Insect Mimetics Research Unit, NIAS, ²Industrial Technology Center of Wakayama Prefecture, ³JITSUBO Co. Ltd.

［Abstract］

We developed a novel fiber-processing technique to produce antimicrobial materials using antimicrobial peptide-polymer conjugates.

［Keywords］

antimicrobial peptide, polymer, antimicrobial fiber

［Background］

Prevention of infectious diseases is a major concern. Because people strongly prefer a clean environment, antimicrobial materials are widely used in Japan. The market for antimicrobial materials is estimated to be 800 billion yen per year. We isolated and identified a beetle defensin and developed defensin-derived antimicrobial peptides (AMP) which have potent antimicrobial activity. We then developed AMP-immobilized antimicrobial cotton fibers that have high durability by conjugation of the AMPs via covalent bonding. Immobilization is a complicated procedure, however, and the fibers could suffer chemical damage from reagents during the processing. Therefore, by using AMP and less severe conditions, we developed a novel technique to obtain fibers with an antimicrobial finish.

［Results and Discussion］

1. We synthesized polymethacrylate-PEG-NH₂ by radical polymerization of methacrylate conjugated with NH₂-PEG as a spacer molecule (Fig. 1). Then maleimide groups were introduced to the spacer (polymer 1). A defensin-derived AMP “peptideA” with addition of an N-terminal cysteine residue (Cys-peptideA) was conjugated to the maleimide groups to obtain polymer 2. The C-terminal cysteine addition variant polymer 3 was also synthesized.
2. These peptide-polymer conjugates were coated onto cotton fibers to obtain an antimicrobial finish.
3. The antimicrobial activities of the fibers were determined by absorption methods. The fibers were washed and sterilized by autoclaving and the antimicrobial assays were repeated.
4. Both polymer 2 and 3 coated fibers showed potent antimicrobial activities (Table 1). The antimicrobial finish was durable for at least 10 cycles of washing and autoclaving.

1. This method for producing antimicrobial cotton fibers is similar to standard procedures in textile polymer-processing and would not require investment in novel facilities.
2. It is expected that these antimicrobial materials would be widely used after reducing the cost of peptide synthesis.

Fig. 1. Synthesis of antimicrobial peptide-polymer conjugates

Table 1. Bacteriostatic activity values of antimicrobial peptide-polymer conjugates processed cotton fiber

Japan Textile Evaluation Technology Council’s certification standard for antimicrobial finished textile: Bacteriostatic activity value >2.2 (bold)

[Reference]

1. Nakamura M, Iwasaki T, Tokino S, Asaoka A, Yamakawa M, Ishibashi J (2011) Development of a bioactive fiber with immobilized synthetic peptides designed from the active site of a beetle defensing Biomacromolecules 12(5):1540-1545
2. Patent application# JP-2011-202173 (Japan)