Hydrolytic Degradability, Cell Tolerance and On-Demand Antibacterial Effect of Electrospun Photodynamically Active Fibres

Abstract

Photodynamically active fibres (PAFs) are a novel class of stimulus-sensitive systems capable of triggering antibiotic-free antibacterial effect on-demand when exposed to light. Despite their relevance in infection control, however, the broad clinical applicability of PAFs has not yet been fully realised due to the limited control in fibrous microstructure, cell tolerance and antibacterial activity in the physiologic environment. We addressed this challenge by creating semicrystalline electrospun fibres with varying content of poly[(l-lactide)-co-(glycolide)] (PLGA), poly(ε-caprolactone) (PCL) and methylene blue (MB), whereby the effect of polymer morphology, fibre composition and photosensitiser (PS) uptake on wet state fibre behaviour and functions was studied. The presence of crystalline domains and PS–polymer secondary interactions proved key to accomplishing long-lasting fibrous microstructure, controlled mass loss and controlled MB release profiles (37 °C, pH 7.4, 8 weeks). PAFs with equivalent PLGA:PCL weight ratio successfully promoted attachment and proliferation of L929 cells over a 7-day culture with and without light activation, while triggering up to 2.5 and 4 log reduction in E. coli and S. mutans viability, respectively. These results support the therapeutic applicability of PAFs for frequently encountered bacterial infections, opening up new opportunities in photodynamic fibrous systems with integrated wound healing and infection control capabilities.

Multifunctional fibrous wound dressings for refractory wound healing

“…The fibers integrated with PSs or PTAs can be used to treat certain cancers, dermatological conditions, and bacterial infections, etc., named phototherapy, including photodynamic therapy (PDT) and photothermal therapy (PTT), with advantages of controllable excitation light, high spatial and temporal precision, and noncontact 95–97 . During the process of photodynamic antibacterial therapy (PDAT), PSs are excited by light of appropriate wavelength, and the excited PSs react with molecule oxygen to generate cytotoxic ROS, which can damage multiple biomolecular targets and lead to the death of bacteria finally 98 .…”

“…The fibers integrated with PSs or PTAs can be used to treat certain cancers, dermatological conditions, and bacterial infections, etc., named phototherapy, including photodynamic therapy (PDT) and photothermal therapy (PTT), with advantages of controllable excitation light, high spatial and temporal precision, and noncontact. [95][96][97] During the process of photodynamic antibacterial therapy (PDAT), PSs are excited by light of appropriate wavelength, and the excited PSs react with molecule oxygen to generate cytotoxic ROS, which can damage multiple biomolecular targets and lead to the death of bacteria finally. 98 For example, El-Khordagui et al incorporated methylene blue (MB) into polyhydrohybutyrate/ polyethylene glycol (PHB/PEG) electrospun nanofibers, which could protect the photoactivity of the entrapped MB and enhance its photodynamic activity against both S. aureus and methicillin-resistant S. aureus (MRSA).…”

Photodynamic Antimicrobial Chemotherapy: Advancements in Porphyrin-Based Photosensitize Development

“…Nanosystems such as polymeric nanoparticles have been loaded with porphyrins to enhance the delivery to microorganisms and improve PACT activity. The polymeric nanosystems in focus have been on systems coined from biocompatible and biodegradable polymers such as from polylactic glycolic acid (PLGA) ( Mai et al, 2020 ), poly(ε-caprolactone) (PCL) ( Liu et al, 2017 ; Kubát et al, 2019 ; Chen et al, 2020 ; Contreras et al, 2020 ), gelatin ( Kirar et al, 2019 ), and cyclodextrins ( Ferro et al, 2009 ; Castriciano et al, 2017 ; Khurana et al, 2019 ; Zagami et al, 2020 ). Several reports of many nanosystems for PACT have been reported with great success as shown in Table 2 .…”

Latest trends on photodynamic disinfection of Gram-negative bacteria: photosensitizer’s structure and delivery systems

“…More recently, Contreras et al have also investigated Photodynamically Active Fibers (PAFs) based on poly(L-lactide) co-(glycolide) and poly(ε-caprolactone) loaded with MB [109] . Moreover, The MB-encapsulated electrospun fibers showed a good structure stability, as well as a controlled released of MB over 3 weeks.…”