Antimicrobial Photodynamic Therapy for the Remote Eradication of Bacteria

Abstract

The emergence of multi‐drug resistant bacteria strains has been an uphill battle in modern healthcare worldwide, due to the increasing difficulty of killing them. The evolving pathogenicity of bacteria has led to researchers searching for more effective antimicrobial therapeutics to successfully eliminate them without undesirable consequences to the human body. In recent years, antimicrobial photodynamic therapy (APDT), an obsolete technique for cancer treatments, has been reported to eradicate bacteria and biofilm‐related infections. The principle of antimicrobial photodynamic therapy solely relies on the photosensitizers (PSs) generating reactive oxygen species, in the presence of oxygen and light, to destroy pathogens. Thus, it can target a broad spectrum of microorganisms, owing to the indirect interaction between PSs and the bacteria, resulting in the less likelihood for the development of drug resistant bacteria strains. This review will focus on the recent progress of APDT in the last five years and some future perspectives of APDT. The mechanism of APDT against bacteria and biofilms, various PSs used for APDT, and some common multidrug‐resistant bacteria strains will be briefly introduced. The reported in vivo applications of APDT in the several types of bacterial infections that includes periodontitis, wound infections, keratitis, endophthalmitis and tuberculosis in the last five years will be summarized in detail.

Reactive Oxygen Species (ROS)-Mediated Antibacterial Oxidative Therapies: Available Methods to Generate ROS and a Novel Option Proposal

“…During antibacterial PDT, type I and type II reactions can occur simultaneously, and the ratio between these processes depends on the type of PS utilized, its chemical structure and the specific microenvironment in which the PDT is implemented. The interplay between type I and type II mechanisms is a critical factor to consider for an optimized treatment and understanding its underlying photochemical processes [88][89][90]. As already reported, ROS are detrimental for bacteria by targeting several vital microbial molecules, such as proteins, lipids, and nucleic acids, thus determining bacterial death.…”

In Situ Single-Cell Bacterial Imaging Provides Mechanistic Insight into the Photodynamic Action of Photosensitizer-Loaded Hydrogels

“…These materials are becoming important as a promising solution for wound management due to their tunability, softness, permeability, biocompatibility, or biodegradability. − In the context of drug delivery, hydrogels benefit from their porosity, which enables drug encapsulation within a 3D polymeric network. Some antibacterial hydrogels have been particularly valuable in the context of light-induced therapies such as antimicrobial photodynamic therapy (aPDT). − aPDT combines light, molecular oxygen, and a photosensitizer to generate reactive oxygen species (ROS) that oxidize lipids, proteins, DNA, and other biomolecules, leading to bacterial inactivation. − Good transparency is, therefore, needed for hydrogels to perform well in aPDT, especially for wound dressing applications, and previous work has focused on optimizing their optical properties. , It was shown that electron-beam polymerized polyethylene glycol diacrylate (PEGDA) hydrogels have a higher transmittance over a broader wavelength range compared to their UV-cured counterparts, reaching values well above 90% …”

Antibacterial Photodynamic Therapy by Zn(II)‐Curcumin Complex: Synthesis, Characterization, DFT Calculation, Antibacterial Activity, and Molecular Docking

“…[15][16][17][18] The main principle behind aPDT's antibacterial effect is based on the light-driven Reactive Oxygen Species (ROS) generation of a light-responsive molecule (termed a photosensitizer). [19,20] In PDT, transition metal complexes have generated a new regime and direction. [21][22][23][24][25][26][27][28] For example, TLD1433 is in clinical trials as a PDT agent to treat bladder cancer.…”

“…In this regard, antibacterial photodynamic therapy (aPDT) has emerged as a non‐invasive and alternate therapeutic modality to overcome antibacterial drug resistance issues [15–18] . The main principle behind aPDT′s antibacterial effect is based on the light‐driven Reactive Oxygen Species (ROS) generation of a light‐responsive molecule (termed a photosensitizer) [19,20] . In PDT, transition metal complexes have generated a new regime and direction [21–28] .…”