Organic Photo-antimicrobials: Principles, Molecule Design, and Applications

Abstract

The emergence of multi-drug-resistant pathogens threatens the healthcare systems world-wide. Recent advances in phototherapy (PT) approaches mediated by photo-antimicrobials (PAMs) provide new opportunities for the current serious antibiotic resistance. During the PT treatment, reactive oxygen species or heat produced by PAMs would react with the cell membrane, consequently leaking cytoplasm components and effectively eradicating different pathogens like bacteria, fungi, viruses, and even parasites. This Perspective will concentrate on the development of different organic photo-antimicrobials (OPAMs) and their application as practical therapeutic agents into therapy for local infections, wound dressings, and removal of biofilms from medical devices. We also discuss how to design highly efficient OPAMs by modifying the chemical structure or conjugating with a targeting component. Moreover, this Perspective provides a discussion of the general challenges and direction for OPAMs and what further needs to be done. It is hoped that through this overview, OPAMs can prosper and will be more widely used for microbial infections in the future, especially at a time when the global COVID-19 epidemic is getting more serious.

Organic photosensitizers for antimicrobial phototherapy

“…Currently, phototherapy usually refers to the combination of harmless low-intensity light and an exogenous light-activated agent (termed a photosensitizer, PS) to enhance the therapeutic effects of light, in which the PS plays a critical role. 15,16 Phototherapy mainly includes photodynamic therapy (PDT) and photothermal therapy (PTT). 7 Due to the efficient light-harvesting capability of PSs, this approach allows phototherapy using low-intensity light with high selectivity.…”

“…Nanotechnology offers advantages in improving the solubility of poorly watersoluble drugs, the circulation time in the bloodstream as well as minimizing the enzymatic degradation of the drug and the undesirable side effects for medical applications. 16,20 More interestingly, the combination of phototherapy with other therapies can overcome the inherent drawbacks of phototherapy as well as maximize the advantages of each therapeutic modality. 3,12 Thus, more research to achieve successful therapeutic agents for further translation to clinical practice is of great interest.…”

A Bacteria‐Responsive Porphyrin for Adaptable Photodynamic/Photothermal Therapy

“…Owing to large extinction coefficients, porphyrins and their derivatives have been extensively applied for fluorescence imaging, photodynamic therapy (PDT), as well as photothermal therapy (PTT) [3–10] . Porphyrin‐based PTT and PDT are non‐contact, convenient, and effective therapeutic methods with low risk in generating drug resistance, and have been applied in clinical treatments for bacterial infections [11–28] . In general, porphyrin derivatives with heavy atoms, cations, and appropriate substituents are commonly used in antimicrobial PDT owing to their high yield of reactive oxygen species, good affinity with bacterial membranes, and non‐stacking properties [29–32] .…”

“…[3][4][5][6][7][8][9][10] Porphyrin-based PTT and PDT are non-contact, convenient, and effective therapeutic methods with low risk in generating drug resistance, and have been applied in clinical treatments for bacterial infections. [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] In general, porphyrin derivatives with heavy atoms, cations, and appropriate substituents are commonly used in antimicrobial PDT owing to their high yield of reactive oxygen species, good affinity with bacterial membranes, and non-stacking properties. [29][30][31][32] While for PTT treatments, porphyrin derivatives with changed π electrons, larger conjugated structures, and aggregated morphologies are usually designed because of their red-shifted absorption and high non-radiative decay efficiency.…”

Nanoarchitectonics of Electrically Activable Phosphonium Self-Assembled Monolayers to Efficiently Kill and Tackle Bacterial Infections on Demand

“…Furthermore, strategies that delay or prevent the continuous release of active substances have been developed [14] from bacterial infection microenvironmentresponsive surfaces (pH, bacterial enzymes (lipases, hyaluronidases), etc.) [15] or light [16]. Although some of them appear promising, these coatings often lead to a gradual leaching of the biocidal substances.…”