Metal–organic framework- and graphene quantum dot-incorporated nanofibers as dual stimuli-responsive platforms for day/night antibacterial bio-protection

Development of advanced antibacterial nanomaterials is important to prevent pathogenic microbial contamination and achieve bioprotection. Herein, we developed dual-stimuli-responsive nanoplatforms with efficient antibacterial activity based on electrospun polycaprolactone/hydroxypropyltrimethylammonium chloride chitosan (PQ) nanofiber membranes (NFMs) incorporated with naringenin-loaded zeolitic imidazolate framework-8 (NAR@ZIF-8) and graphene quantum dots (GQDs). These NFM nanoplatforms could simultaneously be used as “smart” pH-responsive controlled-release and photocatalytic systems. NAR was encapsulated in the microporous structure of the ZIF-8 channel, with a loading capacity of 22.57%. NAR@ZIF-8- and GQD-incorporated PQ (PQZG) nanofibers exhibited enhanced thermal stability and mechanical properties. The release kinetics and microstructure of the nanocarriers demonstrated that the acid-sensitive cleavable crystal structure of ZIF-8 resulted in the pH-responsive release of NAR from PQZG NFMs. Moreover, the presence of GQDs significantly enhanced the photoinduced reactive oxygen species (ROS) generation by NFMs. pH-triggered NAR release and photoinduced ROS generation improved the antibacterial efficacy of PQZG NFMs, forming the synergetic chemical-photodynamic strategies of the dual stimuli-responsive nanoplatforms. Additionally, cytotoxicity experiments revealed that the PQZG NFMs were non-toxic and had good biocompatibility. Therefore, the designed composite nanomaterials combined with the two antibacterial strategies can aid in the development of biosafe nanofibrous membranes for antibacterial or multifunctional bio-protection.