Poly(α-l-lysine) (PLL) is a class of water-soluble, cationic biopolymer composed of α-l-lysine structural units. The previous decade witnessed tremendous progress in the synthesis and biomedical applications of PLL and its composites. PLL-based polymers and copolymers, till date, have been extensively explored in the contexts such as antibacterial agents, gene/drug/protein delivery systems, bio-sensing, bio-imaging, and tissue engineering. This review aims to summarize the recent advances in PLL-based nanomaterials in these biomedical fields over the last decade. The review first describes the synthesis of PLL and its derivatives, followed by the main text of their recent biomedical applications and translational studies. Finally, the challenges and perspectives of PLL-based nanomaterials in biomedical fields are addressed.

The skin is the body's primary immune barrier, defending it against pathogenic invasion. Skin injuries impose a significant physiological burden on patients, making effective wound management essential. Dressings are commonly employed in wound care, and electrospun nanofiber dressings are a research hotspot owing to their ease of fabrication, cost-effectiveness, and structural similarity to the extracellular matrix. Coaxial electrospinning offers considerable advantages in drug delivery, fiber structure transformation, and enhanced interaction with the host. These attributes make coaxial electrospun materials promising candidates for precision and personalized wound dressings in medical treatments. This review provides a comprehensive overview of wound healing and its influencing factors. It also outlines coaxial electrospinning's production principles and benefits in wound dressings. Guided by the factors affecting wound healing, coaxial electrospun nanofiber dressings have different application modalities. Furthermore, we discuss the current limitations and future directions for enhancing the current coaxial electrospun dressing technologies.

Molecular architecture is a largely neglected and unexplored factor that could impart a significant difference to the antimicrobial activity of antimicrobial peptides. In this article, the advantages (i.e., improved charging effect and enhanced proteolytic stability) of star‐shaped poly(l‐lysine)s (PLLs) over their linear analogs are extensively explored by the methods of computational simulation and experiments. A series of PEI‐g‐PLL with a hyperbranched polyethylenimine (PEI) core and PLL peripheral chains are designed as a class of versatile molecular scaffold for the development of star‐shaped antimicrobial peptides. Computational simulations and zeta‐potential measurements reveal that the change in PLL conformation from linear to star‐shaped significantly increases the cationic charge density, allowing enhanced binding affinity toward the bacterial membrane. The minimum inhibitory concentration and killing kinetics measurements demonstrate that PEI‐g‐PLLs exhibit higher antimicrobial activity and bactericidal efficiency in vitro than the linear PLL counterparts. The absence of hydrophobic segments in PEI‐g‐PLLs weakens the nonspecific interactions with eukaryotic cells and offers remarkable selectivity, as evidenced by their negligible hemolytic activity. Furthermore, PEI‐g‐PLLs demonstrate enhanced proteolytic stability and unprecedented antimicrobial activity in vivo. PEI‐g‐PLLs, with their high antimicrobial activity, enormous selectivity, and remarkable proteolytic stability, represent a new series of potent antimicrobial peptides to treat drug‐resistant infections.

The self-assembly of amphiphilic peptide I₃K (Ac-I₃K-NH₂) and its potential application as a drug nanocarrier have been investigated. I₃K monomers and nanotubular segments were initially the dominant species in aqueous solution and they gradually self-assembled into mature nanotubes with heights of approximately 12 nm and lengths of more than 1 μm. The encapsulation properties of the self-assembled peptide nanotubes were then investigated using model compound guests, including anionic hydrophilic methyl orange (MO) and hydrophobic oil red. It revealed that the model compounds could be efficiently encapsulated by I₃K assemblies via electrostatic and hydrophobic interactions, respectively. Atomic force microscopy images demonstrated that variations in drug concentration did not significantly alter the structures of the peptide assemblies but could affect their sizes. Circular dichroism analyses indicated the predominance of β-sheet conformation associated with the self-assembled system regardless of drug concentrations. The in vitro releasing behavior of the encapsulated model drugs was also studied by the techniques of dialysis. The entrapped model drug MO exhibited an accelerated release as the solution pH was either decreased to 2.0–3.0 or increased to 10.0–11.0 but revealed a sustained release at physiological pH. These results demonstrated that these self-assembled peptide nanotubes could serve as potential drug nanocarriers with efficient encapsulation ability, and sustained and pH-responsive release properties.