Polyamide-6 (PA) is a popular textile polymer having desirable mechanical and thermal properties, chemical stability, and biocompatibility. However, PA nanofibers are prone to bacterial growth and user discomfort. ε-Poly-L-lysine (PL) is non-toxic, antimicrobial, and hydrophilic but lacks spinnability due to its low molecular weight. Given its similar backbone structure to PA, with an additional amino side chain, PL was integrated with PA to develop multifunctional nanofibers. This study explores a simple, scalable method by which to obtain PL nanofibers by utilizing the structurally similar PA as the base. The goal was to enhance the functionality of PA by addressing its drawbacks. The study demonstrates spinnability of varying concentrations of PL with base PA while exploring compositions with higher PL concentrations than previously reported. Electrospinning parameters were studied to optimize the nanofiber properties. The effects of PL addition on morphology, hydrophilicity, thermal stability, mechanical performance, and long-term antimicrobial activity of nanofibers were evaluated. The maximum spinnable concentration of PL in PA-based nanofibers resulted in super hydrophilicity (0° static water contact angle within 10 s), increased tensile strength (1.02 MPa from 0.36 MPa of control), and efficient antimicrobial properties with long-term stability. These enhanced characteristics hold promise for the composite nanofiber’s application in medical and protective textiles.

A novel electrospun nanofiber was developed using polyamide-6 (PA) and ε-poly-L-lysine (PL). PA is a popular textile polymer having desirable mechanical and thermal properties, chemical stability, and biocompatibility. However, PA nanofibers are prone to bacterial growth and user discomfort. PL, a natural homopolyamide, is non-toxic, antimicrobial, and hydrophilic but lacks spinnability due to its low molecular weight. Given its similar backbone structure as PA, with an additional amino side chain, PL was integrated with PA to develop multifunctional nanofibers. This study explores a simple, scalable method to obtain PL nanofibers by utilizing the structurally similar PA as the base. The goal was to enhance the functionality of PA by addressing its drawbacks. The study demonstrates spinnability of varying concentrations of PL with base PA while exploring compositions with higher PL concentrations than previously reported. Electrospinning parameters were studied to optimize the nanofiber properties. The effects of PL addition on morphology, hydrophilicity, thermal stability, mechanical performance, and long-term antimicrobial activity of nanofibers were evaluated. The inclusion of PL in PA-based nanofibers resulted in super hydrophilicity, increased tensile strength, and efficient antimicrobial properties with long-term stability. These enhanced characteristics hold promise for the composite nanofiber’s application in medical and protective textiles.

Nanofibers are fibers with diameters less than 1,000 nm having advantageous properties over conventional fibers, such as low bulk and large surface area. Electrospinning is a commonly used technique for nanofiber formation. The working principle of electrospinning is based on the development of a liquid jet from a droplet in the presence of electric field. This chapter discusses the working principle of a traditional electrospinning setup and associated spinning parameters affecting the spinnability of nanofibers. The chapter further discusses drawbacks in the traditional setup and thus the invention of existing modifications to the traditional electrospinning setup. The modifications of electrospinning discussed in this chapter include multiple needle electrospinning, needleless electrospinning, coaxial electrospinning, near-field electrospinning, and bubble electrospinning. The chapter concludes with potential future directions for electrospinning modifications.

Textiles can host microorganisms making antimicrobial function an essential safety feature. An ideal antimicrobial agent is non-nontoxic, stable, and durable. This study explores a core-shell nanofiber with core of cationic biopolymer ε-poly-L-lysine (PL) and shell of structurally similar and biocompatible polyamide-6 (PA). The core-shell structure is expected to have stable antimicrobial function than its monolithic counterpart. Further, thermal crosslinking is expected to prevent rapid diffusion of the water-soluble PL. Therefore, this study establishes a comparison between a monolithic (Control), a core-shell (CS), and thermally crosslinked core-shell (CL-CS) nanofiber of PL and PA. Morphological analysis confirmed the successful generation of the core-shell nanofibers. The samples exhibited hydrophilic behavior that is desirable in various functional textiles. All the samples exhibited antimicrobial function. Unlike control, CS and CL-CS showed no significant difference between the antimicrobial activity after 24 hours and 21 days of bacterial incubation. Therefore, the core-shell structure allowed sustainable and durable antimicrobial action. Lastly, CL-CS sample exhibited reusable antimicrobial function owing to the core-shell structure paired with thermal crosslinking. This study showcases a fiber system with non-toxic, durable, and reusable antimicrobial function. This study builds grounds for the development and multifaceted holistic characterization of safe, stable, and scalable antimicrobial textiles.