Photodynamic disinfection and its role in controlling infectious diseases

Abstract

Photodynamic therapy is witnessing a revival of its origins as a response to the rise of multi-drug resistant infections and the shortage of new classes of antibiotics. Photodynamic disinfection (PDDI) of microorganisms is making progresses in preclinical models and in clinical cases, and the perception of its role in the clinical armamentarium for the management of infectious diseases is changing. We review the positioning of PDDI from the perspective of its ability to respond to clinical needs. Emphasis is placed on the pipeline of photosensitizers that proved effective to inactivate biofilms, showed efficacy in animal models of infectious diseases or reached clinical trials. Novel opportunities resulting from the COVID-19 pandemic are briefly discussed. The molecular features of promising photosensitizers are emphasized and contrasted with those of photosensitizers used in the treatment of solid tumors. The development of photosensitizers has been accompanied by the fabrication of a variety of affordable and customizable light sources. We critically discuss the combination between photosensitizer and light source properties that may leverage PDDI and expand its applications to wider markets. The success of PDDI in the management of infectious diseases will ultimately depend on the efficacy of photosensitizers, affordability of the light sources, simplicity of the procedures, and availability of fast and efficient treatments. Graphic abstract

Prokaryotic and eukaryotic toxicity of halloysite decorated with photoactive nanoparticles

“…2 Several types of nanomaterials are the focus of attention such as inorganic and organic nanoparticles, layered structures, and photosensitive metal complexes. [3][4][5][6] Depending on the composition and structure, nanomaterials may inactivate bacteria under the influence of ultraviolet, visible or infrared irradiation. [7][8][9] In this paper we aim to show the main conceptions of lightassisted bacteria deactivation as well as shine light on the prospects of natural clay nanotubes as a carrier for scalable photoactive nanomaterials for disinfection technologies and biomedical applications.…”

Photodynamic disinfection of SARS-CoV-2 clinical samples using a methylene blue formulation

“…It is unlikely that, in less than 5 min, MB molecules penetrated virions, intercalated with viral nucleic acid and photo-inactivated it. The size of SARS-CoV-2 virions is ~ 100 nm [ 32 ] and the effective diffusion length of singlet oxygen is ~ 200 nm [ 15 ]. It is more likely that MB molecules adhered to viral envelope, generated singlet oxygen at the surface of the virions and the singlet oxygen diffused inside the particle, where it is more soluble than in the aqueous media, and then oxidized the viral RNA.…”

“…It is more likely that MB molecules adhered to viral envelope, generated singlet oxygen at the surface of the virions and the singlet oxygen diffused inside the particle, where it is more soluble than in the aqueous media, and then oxidized the viral RNA. It is well-known that singlet oxygen reacts with proteins, nucleotides and lipids with rate constants of ~ 10 4 , ~ 10 3 and ~ 10 2 L/(g s), respectively [ 15 ]. This is a manifestation of the multi-target ability of ROS, often related to the fact that PDT is not readily associated with mechanisms of drug resistance.…”

“…MB has been in clinical use in various antimicrobial fields for a century [ 14 ], and its use was approved by the FDA for the treatment of patients with acquired methemoglobinemia, opening the way for drug repurposing. MB is also one of the most widely used and better characterized photosensitizers, with remarkable clinical effect in a variety of infectious diseases [ 15 ]. Interestingly, a cohort of 2500 patients treated among others with MB for cancer care did not develop influenza-like illness during the COVID-19 pandemic, suggesting that MB played a protective role [ 16 ].…”

Photoinduced Antibacterial Activity and Cytotoxicity of CdS Stabilized on Mesoporous Aluminosilicates and Silicates

“…Light stimulated destruction of prokaryotic cells in presence of photoactive nanomaterials is a promising direction with wide application possibilities [ 2 ]. Several types of nanomaterials are in a focus of attention such as inorganic and organic nanoparticles, layered structures, photosensitive metal complexes [ 3 , 4 , 5 , 6 ]. Depending on the composition and structure, nanomaterials may inactivate bacteria under the influence of ultraviolet, visible or infrared irradiation.…”