Fundamentals and applications of metal nanoparticle- enhanced singlet oxygen generation for improved cancer photodynamic therapy

Abstract

The introduction of nanotechnology in the field of Photodynamic Therapy (PDT) has proven to have great potential to overcome some of the challenges associated with traditional organic photosensitizers (PS) with respect to their solubility, drug delivery, distribution and site-specific targeting. Other focused areas in PDT involve high singlet oxygen production capability and excitability of PS by deep tissue penetrating light wavelengths. Owing to their very promising optical and surface plasmon resonance properties, combination of traditional PSs with plasmonic metallic nanoparticles like gold and silver nanoparticles results in remarkably high singlet oxygen production and extended excitation property from visible and near-infrared lights. This review summarizes the importance, fundamentals and applications of on plasmonic metallic nanoparticles in PDT. Lastly, we highlight the future prospects of these plasmonic nanoengineering strategies with or without PS combination, to have a significant impact in improving the therapeutic efficacy of cancer PDT.

Efficacy of Antimicrobial Photodynamic Therapy Mediated by Photosensitizers Conjugated with Inorganic Nanoparticles: Systematic Review and Meta-Analysis

“…Nanoparticles based on metal and silica offer advantages over organic nanoparticles, such as having easy-to-control particle sizes, shape, porosity, and monodispersibility; however, these inorganic nanoparticles do not readily degrade in the biological system [ 62 ]. Among all metallic nanoparticles used in photodynamic therapy, gold nanoparticles are the most studied [ 63 , 64 ]. Gold and silver nanoparticles show a special optical phenomenon named localized surface plasmon resonance (LSPR) [ 63 ].…”

“…LSPR occurs when light interacts with conductive metallic nanoparticles that are smaller than the incident wavelength. Consequently, a rapid energy transfer from the metal surface to molecular O 2 (oxygen molecule) with high efficiency occurs and forms 1 O 2 (singlet molecular oxygen), inducing aPDT even without the involvement of PS [ 63 , 64 ]. Silica nanoparticles are biocompatible, easy to produce, and show high photosensitizer loading capacities [ 65 ], and when loaded with antimicrobial compounds, silica nanoparticles have been shown to be capable of reversing antibiotic resistance [ 66 ].…”

Colloidal Quantum Dots as an Emerging Vast Platform and Versatile Sensitizer for Singlet Molecular Oxygen Generation

“…(ii) In the type II process, ,, the excited triplet state interacts directly with 3 O 2 producing 1 O 2 − ,, (Figure ). It is noteworthy that reaction types I and II proceed simultaneously in a competitive manner; however, the ratio of both depends upon the type of sensitizers, the concentration of molecular oxygen, and the substrate category. In clinical practices, the efficiency of 1 O 2 generation by a type II reaction is considered to be the principal determinant of PDT efficacy.…”

Nanomaterials as carriers to improve the photodynamic antibacterial therapy

“…There are two main types of photochemical mechanisms of PDAT (Figure 1), including type I reactions and type II reactions (Gupta et al, 2021;Lin et al, 2021;George et al, 2022). Among them, the type I reaction means that after the photosensitizer enters the bacteria, under the irradiation of light of a certain wavelength, the photosensitizer that absorbs photon energy transitions from the ground state S0 to the excited state S1, in which part of the energy is radiated in the form of fluorescent quantum, and the remaining energy will be photosensitive (Winifred Nompumelelo Simelane and Abrahamse, 2021;Donzello et al, 2022;Yu et al, 2022).…”