Hydrogels: soft matters in photomedicine

Abstract

Photodynamic therapy is a powerful tool in photomedicine. Hydrogels represent very promising candidates to overcome current limitations of this therapeutic technique, such as drug solubility and targeting, and unleash its full potential.

Light and Hydrogels: A New Generation of Antimicrobial Materials

“…On this topic, several most interesting reviews dealing with PDT, hydrogels and their use in medicine have been published [34,53]. Briefly, the antibacterial mechanism of action is based on the generation of reactive oxygen species (ROS) because of an energy transfer from a light-absorbing chromophore-based compound called photosensitizer (PS) in its excited triplet state to molecular oxygen (Figure 15) [34,53,63,86]. The photosensitizer goes from its fundamental electronic singlet state to a short-lived excited singlet state ( 1 PS*) upon irradiation under an adequate wavelength.…”

“…When it comes to hydrogels for which antibacterial properties are light-sensitive, their mechanism of action falls in line with photodynamic therapy (PDT). On this topic, several most interesting reviews dealing with PDT, hydrogels and their use in medicine have been published [34,53]. Briefly, the antibacterial mechanism of action is based on the generation of reactive oxygen species (ROS) because of an energy transfer from a lightabsorbing chromophore-based compound called photosensitizer (PS) in its excited triplet state to molecular oxygen ( Figure 15) [34,53,63,86].…”

“…For hydrogels for which antibacterial properties are based on the light-triggered generation of ROS or [ 1 O2], photosensitizers are usually included in the preparation mixture and embedded in the final 3D polymeric network, either by grafting them onto oligomeric Depending on the reactive species formed, two types of PDT can be distinguished [34,53,63,86]. Redox reactions between 3 PS* and substrates in the studied environment leading to the generation of radicals, which ultimately interact with molecular oxygen and other compounds in the environment to form oxygen, peroxide or hydroxide radicals, constitutes type I.…”

“…Ultimately, they reported a stable, biocompatible and biodegradable thermo-responsive graphene-based hydrogel with suitable physicochemical properties to be studied as in situ forming injectable polymeric matrices for light-mediated biomedical applications. In the area of aPDT, the most classically studied photosensitizers are porphyrins and their derivatives, a class of hydrophobic and heterocyclic organic photosensitizers composed of four pyrrole subunits [34]. Porphyrins are naturally occurring compounds since they are key constituents for the respiratory system in living organisms [53,86].…”

New, highly versatile bimolecular photoinitiating systems for free-radical, cationic and thiol–ene photopolymerization processes under low light intensity UV and visible LEDs for 3D printing application

“…2 Photoinduced polymerization processes nd application in many branches of the industry, namely in photolithography to produce printed circuits, 3 in the coating industry for photocuring polymer adhesives, 4,5 and even in medicine to obtain hydrogel polymer materials. 6 Another dynamic direction of application is in the printing industry, where photopolymerization is used in making prints on plastic or metal. 7 This process of polymerization also plays a signicant role in the design and formation of 3D models 8,9 using 3D printing technology.…”