The present work is focussed on the principles of photodynamic therapy (PDT), emphasizing the photochemical mechanisms of reactive oxygen species formation and the consequent biochemical processes generated by the action of reactive oxygen species on various biological macromolecules and organelles. This paper also presents some of the most used photosensitizers, including Photofrin, and the new prototypes of photosensitizers, analysing their physicochemical and spectroscopic properties. At this point, the review discusses the therapeutic window of absorption of specific wavelengths involving first- and second-generation photosensitizers, as well as the principal light sources used in PDT. Additionally, the aggregation process, which consists in a phenomenon common to several photosensitizers, is studied. J-aggregates and H-aggregates are discussed, along with their spectroscopic effects. Most photosensitizers have a significant hydrophobic character; thus, the study of the types of aggregation in aqueous solvent is very relevant. Important aspects of the coordination chemistry of metalloporphyrins and metallophthalocyanines used as photosensitizers are also discussed. The state-of-the-art in PDT is evaluated, discussing recent articles in this area. Furthermore, macrocyclic photosensitizers, such as porphyrins and phthalocyanines, are specifically described. The present review is an important contribution, because PDT is one of the most auspicious advances in the therapy against cancer and other non-malignant diseases.

Candidiasis is an opportunistic mycosis with high annual incidence worldwide. In these infections, Candida albicans is the chief pathogen owing to its multiple virulence factors. C. albicans infections are usually treated with azoles, polyenes and echinocandins. However, these antifungals may have limitations regarding toxicity, relapse of infections, high cost, and emergence of antifungal resistance. Thus, the development of nanocarrier systems, such as metal nanoparticles, has been widely investigated. Metal nanoparticles are particulate dispersions or solid particles 10–100 nm in size, with unique physical and chemical properties that make them useful in biomedical applications. In this review, we focus on the activity of silver, gold, and iron nanoparticles against C. albicans. We discuss the use of metal nanoparticles as delivery vehicles for antifungal drugs or natural compounds to increase their biocompatibility and effectiveness. Promisingly, most of these nanoparticles exhibit potential antifungal activity through multi-target mechanisms in C. albicans cells and biofilms, which can minimize the emergence of antifungal resistance. The cytotoxicity of metal nanoparticles is a concern, and adjustments in synthesis approaches or coating techniques have been addressed to overcome these limitations, with great emphasis on green synthesis.

Objective: The present study investigated the effects of low-level laser therapy (LLLT) on the mitochondria, nucleus, and cytoskeleton of CHO K-1 cells by the use of specific fluorescent probes. Background Data: The use of LLLT has been recommended by several authors for acceleration of the healing process. The literature on the effects of LLLT in this process is highly contradictory because of difficulties in identifying its effects on cells. Materials and Methods: CHO K-1 cells were cultivated using MEM containing 5% FBS and were irradiated or not with a semiconductor laser (λ = 830 nm; φ ~ 0.8 mm; 10 mW; 2 J/cm²). The cells were incubated with specific fluorescent probes - 0.1 μM for 30 min with 5,5′,6,6′-tetrachloro-1,1′,3,3′-tetraethyl-benzimidazol-carbocyanine iodide (JC-1) for the mitochondria; 5 mM for 5 min of 4′,6′-diamidino,2′-phenylindole (DAPI) for the nucleus, and 0.1 M of 1:100 PHEM of rhodamine-phalloidin during 1 h for the cytoskeleton - and were analyzed by epifluorescence. Results: Positive biomodulatory effects were observed on irradiated cells compared to their controls as seen on JC-1, DAPI, and rhodamine-phalloidin labeling. Irradiated cells showed an increased level of cellular division, as evidenced by analyzing the intermediary filaments of the cytoskeleton and the chromosomes. Another important observation was that cells maintained under the condition of nutritional deficiency had both membrane and genetic material that was more preserved in comparison to the controls, in which the presence of an apoptotic nucleus could be observed in some cells. Conclusion: The results of the present study demonstrate that LLLT, in addition to providing positive biomodulation, acts in the reestablishment of cellular homeostasis when the cells are maintained under the condition of nutritional stress; it also prevents apoptosis in CHO K-1 cells.