Cyanobacteria-based self-oxygenated photodynamic therapy for anaerobic infection treatment and tissue repair

Abstract

Photodynamic therapy (PDT) is an important technique to deal with drug-resistant bacterial infections in the post-antibiotic era. However, the hypoxic environment in intractable infections such as refractory keratitis and periodontitis, makes PDT more difficult. In this work, spontaneous oxygen-producing cyanobacteria were used as the carrier of photosensitizer (Ce6), and ultrasmall Cu 5.4 O nanoparticles (Cu 5.4 O USNPs) with catalase activity for infection and inflammation elimination and rapid tissue repair (CeCycn-Cu 5.4 O). The loading of Ce6 and Cu 5.4 O USNPs onto cyanobacteria surface were confirmed by transmission electron microscopy, nano particle size analyzer, scanning electron microscopy. In vitro sterilization and biofilm removal experiments demonstrated that the restriction of hypoxic environment to PDT was significantly alleviated due to the oxygen production of cyanobacteria. Under laser irradiation, the close transfer of energy photons to oxygen produced by cyanobacteria reduced more than 90% of Ce6 dosages (660 nm, 200 mW/cm 2 , 2 min). It is worth mentioning that both rapid sterilization through PDT and long-term oxidized free radicals elimination were achieved by adjusting the ratio of Ce6 and Cu 5.4 O USNPs. Both periodontitis and refractory keratitis animal models proved the excellent self-oxygenation enhanced antibacterial property and promotion of tissue repair.

Chemically engineering cells for precision medicine

“…Besides, some self-oxygenated cyanobacteria can also be leveraged to assist PDT in treating anaerobe infections. 231 Moreover, PDT-generated ICD may work synergistically with immune cells to modulate the anti-tumor immune response. Chemical engineering would be an efficient helper of PDT by endowing these cell-based delivery systems with better targeting abilities and properties controlled anchoring and release of photosensitizers.…”

Antimicrobial Photodynamic Therapy for the Remote Eradication of Bacteria

“…To tackle this issue, one can either increase the oxygen levels around the photosensitizers or prevent photosensitizers to undergo self-quenching. [60] Henceforth, researchers have designed APDT modalities to include a continuous oxygen source such as utilizing cyanobacteria to generate oxygen via photosynthesis [90,157] or having an oxygen carrier like perfluorocarbon. [195] As an example, Bai and his coworkers have designed an oxygen self-supplying nanotherapeutic platform, as illustrated in Figure 5.…”

“…In Figure 3D, Qu and co-workers proposed the use of spontaneous oxygen-producing cyanobacteria as carriers for Ce6 and ultrasmall Cu 5.4 O nanoparticles with catalase activity (CeCycn-Cu 5.4 O) for inflammation eradication in intractable periodontitis. [157] It was reported that adjustments in ratio of Ce6 and ultrasmall Cu 5.4 O nanoparticles allowed for a swift sterilization through APDT and long-term oxidized free radical elimination. The experimented animal models not only revealed the remarkable alleviation of hypoxia, but also immense improvements in self-oxygenated anaerobic bacterial inhibition and tissue repair.…”

Photonics-based treatments: Mechanisms and applications in oral infectious diseases

“…After that, the ROS scavenger removed excess ROS which is beneficial to reduce inflammation and tissue repair. Materials reported with the above functions are CeO 2 @Ce6 with 4 log CFU reduction and cyanobacteria loading Ce6 and Cu 5.4 O (CeCyan-Cu 5.4 O) with about 100% killing of the anaerobic bacteria biofilm Wang et al, 2022).…”