Antimicrobial photodynamic therapy (aPDT) is believed to be a promising approach that can avoid developing drug resistance and be applied in the infection treatment. However, for deep-tissue infection, it has weak therapeutic efficacy because of the limited penetration depth of visible excitation light.
In a study published in Nanoscale, the research group led by Prof. CHEN Zhuo at Fujian Institute of Research on the Structure of Matter of Chinese Academy of Sciences reported an efficient near-infrared-triggered nano-photosensitizer with promising antifungal and antibacterial efficacy for deep-tissue antimicrobial therapy.
Researchers first prepared a photosensitizer (β-carboxyphthalocyanine zinc, CPZ) delivery system with lanthanide-doped upconversion nanoparticles (UCNPs, LiYF4:Yb/Er) and polyvinylpyrrolidone (PVP) as UCNPs-CPZ-PVP, and investigated its antimicrobial (antibacterial and antifungal) activities both in vitro and in vivo.
The in vitro antimicrobial experiments revealed that UCNPs-CPZ-PVP has a high anti-infectious activity against multi-drug resistant (MDR) bacteria (methicillin-resistant Staphylococcus aureus by 4.7 log10 and MDR Escherichia coli by 2.1 log10) post aPDT (at 50 μg/mL UCNPs-CPZ-PVP with 0.5 W/cm2 980 nm light), as well as a high antifungal efficacy against Candida albicans.
Besides, they carried out the in vivo aPDT experiments using an MDR bacterial infection murine model in the presence of 5 mm thick tissue specimens. The results demonstrated the great potential of UCNPs-CPZ-PVP against infections in deep tissue.
In conclusion, this study revealed an efficient near-infrared-triggered nano-photosensitizer, and provided insights for developing critically needed new antibacterial agents.
Bacterial resistance to antimicrobials is a global concern. It is critical to develop antibacterial agents to treat life-threatening infections caused by highly resistant bacteria.
Schematic representation of efficient near-infrared-triggered antimicrobial photodynamic therapy. (Image by Prof. CHEN’s Group)
Contact:
Prof. CHEN Zhuo
Fujian Institute of Research on the Structure of Matter
Chinese Academy of Sciences
Email: zchen@fjirsm.ac.cn
