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Phototherapy Using Nanomaterials
Published in D. Sakthi Kumar, Aswathy Ravindran Girija, Bionanotechnology in Cancer, 2023
A. N. Resmi, V. Nair Resmi, C. R. Rekha, V. Nair Lakshmi, Shaiju S. Nazeer, Ramapurath S. Jayasree
PDT is a photochemistry-based diseased cell-ablative interventional therapeutic methodology. PDT uses a photo-activatable chemical, named as photosensitizer (PS), and light of a suitable wavelength to impart cytotoxic damage to the diseased cells through generating reactive molecular species [107–109]. Therapeutic activation of the PS is attained by exciting it using an appropriate light (typically 600−800 nm). The activated PS generates cytotoxic ROSs on cells as a result of transfer of energy to molecular oxygen such as singlet oxygen (1O2). This 1O2 oxidizes cellular macromolecules, leading to diseased cell ablation [110].
Extracorporeal Purging of Bone Marrow Grafts by Dye-Sensitized Photoirradiation
Published in Adrian P. Gee, BONE MARROW PROCESSING and PURGING, 2020
The first law of photochemistry states that “only absorbed light can produce a chemical change”. In general, the vital components of an animal cell absorb poorly in the visible range of the spectrum. Consequently, most animal cells are rather insensitive to irradiation with visible light. However, in the presence of suitable light-absorbing molecules (so-called photosensitizers), animal cells can be injured or killed very rapidly by visible light.
Influence of Light on Essential Oil Constituents
Published in K. Hüsnü Can Başer, Gerhard Buchbauer, Handbook of Essential Oils, 2020
Marie-Christine Cudlik, Gerhard Buchbauer
According to the Organisation for Economic Co-operation and Development (OECD) guidelines for the testing of phototoxic potential of substances, phototoxicity is defined as “a toxic response from a substance applied to the body which is either elicited or increased (apparent at lower close levels) after subsequent exposure to light, or that is induced by skin irradiation after systemic administration of a substance” (OECD, 2004). However, acute skin responses to photosensitizing chemicals can also be photoallergic reactions. Those two processes are distinguished in photochemistry, for phototoxic reactions induce toxic cell damage and are non-immunological, but photoallergic reactions, on the other hand, are T-cell-mediated immunological reactions. Most of the substances that elicit photoallergic responses are also phototoxic (Placzek et al., 2007). It can occur as an adverse reaction to cosmetic products or pharmaceutical drugs, and therefore it is an utmost necessity to evaluate the phototoxic potential of the ingredients of such, so as to not put the patient or user at risk. The use of trans-anethole, a major constituent in some EOs, for example, has been the subject of discussion, for when irradiated with UV light, cis-anethole is formed, which does not only possess an unpleasant scent and flavor, but is also toxic (Castro et al., 2010).
Crosslinking for progressive keratoconus: is there room for improvement?
Published in Expert Review of Ophthalmology, 2023
Cosimo Mazzotta, Manuela Agata Pulvirenti, Marco Zagari, Safaa Jihad, Ashraf Armia Balamoun
The introduction of pulsed light represented another step-forward improving oxygen kinetic and aerobic photochemistry together with supplemental oxygen customized treatments. Finally, more standardized protocols with constant fluence (M nomogram) or decreasing fluence (sub400 protocol) are available for the treatment of thin ectatic corneas. Iontophoresis riboflavin loading improved the transepithelial uptake of riboflavin dramatically and the results of Epi-On treatments have been recently further improved with enhanced fluence pulsed light protocols also with chemically-enhanced solutions at higher riboflavin concentration, paving the way for bilateral and full outpatient treatments, thus reducing invasiveness and costs while ensuring greater accessibility to this important therapy.
Influence of infrastructure material composition and microtopography on marine biofilm growth and photobiology
Published in Biofouling, 2021
Baptiste Vivier, Pascal Claquin, Christophe Lelong, Quentin Lesage, Mathias Peccate, Bastien Hamel, Marine Georges, Amel Bourguiba, Nassim Sebaibi, Mohamed Boutouil, Didier Goux, Jean-Claude Dauvin, Francis Orvain
One expected consequence of a lower FV/FM would be a parallel decrease in rETRMAX and the photosynthetic efficiency (i.e. α) because the energy captured by the PSII is diverted from photochemistry to non-photochemical quenching (Ralph et al. 2002). However, the results suggest a better electron transport rate during the first three days of the experiment on the PVC structures. rETRMAX measurements also confirmed the better photosynthetic capacity of MPB on rough structures than on smooth ones, and this was also the case for photosynthetic efficiency. The falling NPQ values on the last day of experiment were concomitant with increasing rETRMAX values and could be explained by the settlement of a well photo-acclimatised MPB biofilm. Additional measurements of a* (Chl a specific absorption coefficient) and σPSII (functional absorption cross-section of PSII) would be useful to interpret the rETRMAX in more detail.
Nano Antiviral Photodynamic Therapy: a Probable Biophysicochemical Management Modality in SARS-CoV-2
Published in Expert Opinion on Drug Delivery, 2021
Khatereh Khorsandi, Sepehr Fekrazad, Farshid Vahdatinia, Abbas Farmany, Reza Fekrazad
Nanomedicine is the medical application of nanotechnology in the diagnosis and treatment of human disease. It uses nanoparticles with dimensions usually ranged between 1 and 200 nm. One of the most critical functions of medical nanotechnology is drug delivery vehicles which could improve drug availability at the target to make the maximum therapeutic benefit [13]. Nanomaterials can improve the solubility of poorly water-soluble drugs, prolong the circulation time in the bloodstream, decrease the enzymatic degradation of drugs, reduce undesirable side effects, and enhance the drug bioavailability [14,15]. Despite the efficacy of aPDT, inefficient PS uptake by bacteria cannot result in efficient treatment. Recently, nano-aPDT has also been developed to improve the photochemical and photophysical effectiveness of aPDT in the presence of nanoparticles [16]. Various nanoparticles (NPs) have been used to enhance the antimicrobial PDT with the aim of improving photosensitizer (PS) solubility, photochemistry, photophysics, and targeting [17].