Search Results (35)

Photobiological hydrogen (H₂) production by microalgae and cyanobacteria is widely seen as a promising and sustainable alternative to H₂ produced from fossil fuels. However, its efficiency remains limited because the enzymes responsible for H₂ production are highly sensitive to oxygen (O₂), while photosynthesis itself generates O₂ that can suppress their activity. This mini-review explores how different photosynthesis inhibitors affect H₂ production in these microorganisms, with a focus on their molecular targets and their physiological effects. In both microalgae and cyanobacteria, compounds such as DCMU, atrazine, DBMIB, CCCP, and KCN influence H₂ metabolism by altering electron transport, O₂ release, proton gradients, and cellular redox balance. The reviewed studies indicate that complete inhibition of photosynthetic electron flow is usually unfavorable for sustained H₂ production because it reduces the electron supply required by H₂-evolving enzymes. Therefore, anaerobiosis is more reliably established by physiological or cultivation-based strategies, whereas photosynthetic and respiratory inhibitors are best used as mechanistic probes or as auxiliary modulators under carefully optimized conditions. Their effects are strongly context-dependent, reflecting the balance between O₂ suppression, residual electron transport, respiratory O₂ consumption, and competing electron sinks. Full article

Conventional photothermal therapy often relies on high-intensity laser excitation due to the limited photothermal conversion efficiency (PCE) of existing photothermal agents (PTAs), which compromises treatment safety and restricts clinical translation. To address this limitation, we designed and synthesized a series of boron-dipyrromethene (BODIPY)-based derivatives (BDP 1–4) featuring gradient-enhanced donor–acceptor (D-A) push–pull electronic effects for efficient photothermal antitumor therapy. The structure–activity relationships were systematically elucidated through photophysical characterization and in vitro/in vivo photobiological evaluation. From BDP 1 to BDP 4, the progressively strengthened push–pull effect leads to enhanced intramolecular charge transfer (ICT), which, in turn, results in a narrowed HOMO-LUMO gap, redshifted absorption into the near-infrared (NIR) region (up to 843 nm), markedly attenuated fluorescence emission, and a remarkable increase in PCE up to 88.3%. To improve water dispersibility and tumor targeting, these molecules were further encapsulated into nanoparticles using DSPE-PEG₂₀₀₀, and the nanoformulations retained high PCE. Both in vitro and in vivo studies demonstrated that under low-power laser irradiation (0.5 W·cm⁻², 808 nm), the nanoformulation of BDP 4, which exhibited the highest PCE among the series, achieved pronounced photothermal tumor ablation without inducing systemic toxicity. Overall, this study proposes a molecular design strategy that synergistically modulates NIR absorption and photothermal conversion by enhancing the D-A push–pull effect. This strategy provides a design rationale for developing efficient, low-toxicity organic PTAs, and demonstrates potential applicability in low-power PTT modalities. Full article

Across much of the Arctic, climate warming has reduced the extent of thicker and more persistent sea ice and increased the prevalence of thinner first-year ice. Thin first-year landfast sea ice is ecologically important because reduced ice thickness can increase light transmission to the ice–water interface, while the associated brine conditions, including salinity and permeability, can strongly influence algal biomass accumulation and photophysiology. This thin (0.24–0.55 m), short-lived, seasonal, first-year landfast sea ice already dominates Nuup Kangerlua fjord, southwest Greenland, making it a useful natural example of ice conditions that may become more common in parts of the future Arctic. We focused on late February–early March because this period captures the seasonal transition from very low winter irradiance toward increasing spring light, when sea ice algal communities begin photosynthetic acclimation prior to the main bloom period. Using this site as an example of future Arctic-like conditions, we investigated chlorophyll a (Chl a) concentration and the photobiology of sea ice algal communities during five sampling events between 2017 and 2022. The vertical distribution of Chl a concentration and photobiological parameters measured with variable chlorophyll fluorescence differed between years, as did Chl a concentrations, with integrated biomass ranging from 0.08 to 0.78 mg Chl a m⁻². Direct under-ice PAR measurements showed transmittance values ranging from 0.013 to 0.29. Bottom-ice communities were acclimated to relatively high light intensities, with E_k often exceeding 200 µmol photons m⁻² s⁻¹, and we detected no clear evidence of photoinhibition in the fluorescence data. Boosted regression tree models identified brine salinity as the main predictor of both Chl a concentration, explaining 42.0% of the variation, and, Φ_{PSII_max}, the maximum dark-adapted photosynthetic efficiency, explaining 86.1% of the variation. Both parameters decreased exponentially with increasing sea ice brine salinity (p < 0.0001), indicating that higher brine salinity was associated with reduced algal biomass and lower photosynthetic efficiency. These results show that short-lived first-year landfast sea ice can support physiologically active sea ice algal communities despite relatively low biomass, and suggest that algal performance in this ice type was more strongly associated with brine salinity during the late-winter to early spring sampling period, while light availability also varied substantially among years. As thin and short-lived sea ice conditions become more common in parts of the Arctic, this habitat may represent an increasingly important, though temporally variable, component of Arctic marine primary production. Full article

Laser acupuncture (LA) integrates principles of traditional acupuncture with photobiomodulation (PBM) and has gained increasing attention as a non-invasive modality for pain management. PBM-based integrative LA in medicine refers to the application of low-level laser irradiation to acupuncture points, combining contemporary biomedical mechanisms with holistic, system-oriented therapeutic principles. This narrative review aimed to critically assess the scientific evidence on the efficacy of LA for pain management within the framework of the Principles of Clinical Integration of Photobiomodulation (PCIPBM) in LA, summarizing frequently used laser parameters and clinical indications. LA involves special protocols in standardized acupoints, using defined parameters of wavelength, irradiation, and energy density, consistent with PBM dosing principles. Therapeutic effects are mediated through point-specific neuromodulation and photobiological mechanisms, including modulation of peripheral and central nociceptive processing, reduction in pro-inflammatory mediators, improvement of microcirculation, and mitochondrial activation via cytochrome c oxidase-dependent adenosine triphosphate (ATP) synthesis. Clinical studies report statistically and clinically significant analgesic effects, particularly in chronic musculoskeletal pain, osteoarthritis, low back and neck pain, temporomandibular disorders, neuropathic pain, and selected postoperative pain conditions, when appropriate laser parameters are applied. Reported adverse effects are minimal, and tolerability is high. LA represents a safe, non-invasive therapeutic option and patient-friendly approach with clinically relevant efficacy in pain management. When applied according to PCIPBM, including evidence-based PBM parameters, it may serve as an effective adjunct or alternative to conventional pharmacologic and interventional approaches. Further standardization and high-quality randomized controlled trials are still required. Full article

Nanotechnology combined with photodynamic therapy (PDT) has been explored to enhance antitumor and antimicrobial photobiological activity. Aluminum phthalocyanine chloride (Al-Pc-Cl), with or without magnetic nanoparticles (MagNPs), was incorporated into polymeric nanoparticles (PNPs) to improve the PDT for treating tumors and infectious diseases. Three batches of the nanoparticles (MagNPs, PNPs-PS and PNPs-PS-MagNPs) were developed and characterized in terms of size, PdI, morphology by TEM, release study, and antitumor (against A549 cells) and antimicrobial (against MRSA and C. albicans) photobiological activity. The developed nanoparticles were nanometric in size, with MagNPs, PNPs-PS, and PNPs-PS-MagNPs showing 33.6, 186.9, and 333.5 nm, respectively, maintained the magnetic properties (for MagNPs and PNPs-PS-MagNPs), and provided slow and sustained release of the photosensitizer. PNPs-PS and PNPs-PS-MagNPs showed excellent antitumor photobiological activity with cell viabilities of 42 and 34%, respectively, and were not cytotoxic in the dark, with cell viabilities above 70%. PNPs-PS showed strong antibacterial activity against MRSA with an IC₅₀ of 8.26 μg/mL, which was lower to free Al-Pc-Cl with an IC₅₀ of 14.22 μg/mL after I radiation. The results of the antifungal photobiological activity against C. albicans were excellent, with IC₅₀ values of 3.75 and 3.5 μg/mL for PNPs-PS and PNPs-PS-MagNPs, respectively, values which were significantly lower with p < 0.05 than free PS (IC₅₀ > 30 μg/mL) after irradiation with light and fluconazole (IC₅₀ > 30 μg/mL), the reference antifungal agent. PNPs-PS showed promising results regarding antitumor, antibacterial, and antifungal photobiological activity. However, PNPs-PS-MagNPs showed weak results for antibacterial photobiological activity against MRSA but with promising results for tumor cells and C. albicans. Full article

Background: The intravascular laser irradiation of blood (ILIB) is a low-power laser technique that has been studied since the 1970s, and it is associated with the substantial capability to modulate various physiological processes. Indeed, ILIB involves the irradiation of blood with low-intensity light, typically within the red or near-infrared spectrum, to trigger a cascade of photochemical and photobiological events. Objective: This study aimed to analyze previous findings regarding ILIB effects on physical performance. Methods: This study is a narrative review of the literature, addressing the effects of ILIB on multiple organ systems and its impact on physical performance. Results: The most found effects include antioxidant activation, inhibition of inflammatory processes, increased blood fluidity, and improved hemorheological properties. The ILIB affects blood rheological properties based on vasodilatation and decreasing aggregation of thrombocytes. Other effects include improved deformability of erythrocytes, which results in a better supply of oxygen and a decrease in the partial pressure of carbon dioxide. Since ILIB is a photobiomodulation procedure, other applications can be considered, such as ergogenic intervention. In this context, ILIB may favor performance in aerobic exercises and contribute to practices involving anaerobic metabolism by facilitating phosphocreatine resynthesis and ATP restoration. Conclusions: Multiple findings seek to support the potential benefits of ILIB on metabolic and cardiovascular responses associated with exercise training, providing potential improvements in athletic performance. Full article

Light variability is a key environmental stressor influencing the physiology and productivity of marine macroalgae. This study examined the ecophysiological and biochemical responses of Lessonia spicata (Ochrophyta) during a natural light deprivation event caused by a solar eclipse. We measured the in vivo chlorophyll a (Chla) fluorescence, photoinhibition, and photosynthetic capacity, along with the pigment content, phenolic compound accumulation, and antioxidant capacity, to evaluate short-term photosynthetic adjustments. Dark-adapted conditions during the eclipse peak led to reduced photosynthetic and biochemical activity, while post-eclipse recovery involved the increased accumulation of photosynthetic pigments and photoprotective compounds. Carotenoids showed high antioxidant potential under eclipse exposure, contrasting with declines in chlorophyll content and productivity under pre-eclipse high irradiance. This study provides valuable insights into the rapid acclimation mechanisms of Lessonia spicata to transient light stress, highlighting its sensitivity and resilience to sudden shifts in solar irradiance. These findings contribute to the broader field of marine macroalgal photobiology and stress physiology, enhancing our understanding of how intertidal brown algae adapt to dynamic environmental conditions. Full article

Hypocrellins (HYPs), naturally occurring 3,10-xylene-4,9-anthracene derivatives sourced from Shiraia bambusicola and Hypocrella bambusae, exhibit significant photobiological activities. Despite their capability for generating a high yield of reactive oxygen species, including singlet oxygen and superoxide anion radical, their application in photodynamic therapy (PDT) is constrained. This limitation is due to their low dark phototoxicity, weak absorption within the therapeutic window of PDT (600–900 nm), and inherent hydrophobicity, which hinder their immediate use in amphipathic PDT applications. This review comprehensively discusses the research advancements in the bioactivities and biosynthesis of HYPs, alongside the reported chemical and physical modifications that enhance their water solubility and extend their therapeutic window. Additionally, it explores potential strategies for developing pharmaceuticals, photocatalytic agents, and photosensitive pesticides based on HYPs. Full article

The estuarine anemone Anthopleura hermaphroditica and its symbiont Philozoon anthopleurum are continuously exposed to intense fluctuations in solar radiation and salinity owing to tidal changes. The aim of this study was to evaluate the effects of the tidal cycle, solar radiation, and salinity fluctuations on the photosynthetic and cellular responses (lipid peroxidation, total phenolic compounds, and antioxidant activity) of the symbiont complex over a 24 h period in the Quempillén River Estuary. Additionally, laboratory experiments were conducted to determine the specific photobiological responses to photosynthetically active radiation (PAR), ultraviolet radiation (UVR), and salinity. Our field results showed that the photosynthetic parameters of the symbiont complex decreased with increasing ambient radiation; however, no relationship was observed with changes in salinity. Increased peroxidative damage, total phenolic compound levels, and antioxidant activity were mainly related to increased UVR and, to a lesser extent, PAR. During the dark period, only PAR-exposed organisms returned to the basal levels of photosynthesis and cell damage. Laboratory exposure confirmed the deleterious effects of UVR on the photosynthetic response. The present study suggests that the ability of A. hermaphroditica to acclimate to natural radiation stress is mediated by the concerted action of various physiological mechanisms that occur at different times of the day, under varying levels of environmental stress. Full article

The effect of a coating material containing organic photoluminophore (PL) on the growth and development of mustard Brassica juncea L. plants colonized with beneficial associative bacteria Pseudomonas putida KT2442 and Rhodococcus erythropolis X5 was studied in vitro and in vivo. Plants grown with the use of microbial bacterization in combination with a photoluminophore coating (PLC) had significantly faster growth rates in vitro (2.1 times faster, P. putida; 1.8 times faster, R. erythropolis) than those grown using PLC alone (1.2 times faster). The leaves of plants grown with PLC had higher contents of glucose and fructose (28.4 ± 0.3% more glucose and 60.4 ± 0.3% more fructose accumulated compared to plants grown without PLC). It was found that seed weights and seed number increased 1.9-fold and 1.6-fold, respectively, for plants grown with PLC and colonized with beneficial P. putida KT2442 bacteria. The stimulatory effect of PLC on photosynthetic parameters of Photosystem II (PSII) was observed in colonized plants grown in vitro. For the first time, it was shown that providing plants with a PLC for only 4 weeks may make it possible to support further plant growth without PLC to obtain higher yields in the future. Thus, PLCs that convert shorter-wavelength radiation into red light may induce enhancement of biochemical processes not only in plants but also in microorganisms that supply plants with growth regulators and other active compounds. The results indicate the need for further research to understand the mechanisms of photobiological and photoregulatory systems in the interaction of microbes and plants. Full article

Photobiological treatment of reverse osmosis concentrate (ROC) using brackish diatoms is a green and sustainable technology that can enhance water recovery by removing dissolved silica from ROC while producing beneficial biomass. This study aimed to determine the optimum conditions for the photobiological treatment of ROC obtained from a full-scale advanced water purification facility using Gedaniella flavovirens Psetr3. While light color presented minor impacts on the silica uptake rate, the impact of color intensity was significant. The uptake rate improved from 28 ± 1 to 48 ± 7 mg/L/day by increasing photosynthetically active radiation (PAR) from 50 to 310 µmol m⁻² s⁻¹. Increasing the PAR further did not improve the performance. The optimum temperature was around 23–30 °C. While the silica uptake was slower at 10 °C, G. flavovirens Psetr3 was unable to survive at 40 °C. Experiments using sunlight as a light source verified the impact of temperature on the silica uptake and the detrimental effect of ultraviolet radiation on this diatom. The sunlight-based treatment effectively removed N-nitrosodimethylamine. The results of this study are being used in subsequent pilot-scale investigations and full-scale technoeconomic analysis and will contribute to the further development of this sustainable water technology. Full article

We developed a system combining visible-light photocatalysis with biological treatment for the continuous removal of phthalate esters (PAEs) from both synthetic and real aquaculture wastewater. We investigated the effects of different operating factors, including the coexistence of glucose or PAEs, on individual PAE removal by using a photobiological system (PBS). In wastewater containing a mixture of PAEs, that is, containing di-(2-ethylhexyl)phthalate (DEHP), dibutyl phthalate (DBP), and dimethyl phthalate (DMP), a coimmobilized bioreactor system comprising the bacterium Pseudomonas putida and the microalga Chlorella vulgaris demonstrated a higher removal efficiency than immobilized P. putida alone or a coculture of immobilized P. putida and suspended C. vulgaris did. The PBS employed for the continuous treatment of real aquaculture wastewater containing DEHP (0.62 ± 0.05 mg/L), DBP (8.7 ± 0.9 mg/L), and DMP (17.4 ± 1.5 mg/L) achieved at least 99.5% PAE removal and 99.2% mineralization efficiency under optimal operating conditions. After 42 days of treatment, inoculated Pseudomonas (98.12%) remained the predominant genus in the bioreactor. The results reveal that the symbiotic microalgal–bacterial system is a feasible alternative to a pure P. putida immobilized bioreactor for reducing CO₂ emissions from mineralized PAEs through microalgal activity. Full article

Phthalocyanines are a group of porphyrin synthetic molecules. These compounds show outstanding photodynamic properties. This is due to their high ability to photogenerate free radicals, such as ¹O₂ and O^.−₂. However, the presence of different metals in the central core of phthalocyanines are able to modulate these characteristics. This study demonstrated that the photochemical activity of Zn, Cu, Ni, Co, Fe and Mn unsubstituted phthalocyanines differs, depending on the size and electronic configuration of the central metal. In addition, phthalocyanines showed different levels of photodamage against plasmid pBR322. Outcoming computational calculations will aim to clarify the photodynamic mechanisms of phthalocyanines. Full article

Regenerative endodontic procedures (REPs) were used to recover the dental pulp’s vitality in order to avoid the undesirable outcomes of conventional endodontic treatment and to promote dentinal formation, especially for immature permanent teeth. Photobiomodulation therapy (PBMT) exhibits photobiological and photochemical effects for improving the root canal’s environmental conditions by compensating for oxidative stress and increasing the blood supply to implanted stem cells and improving their survival. Basic research has revealed that PBMT can modulate human dental pulp stem cells’ (hDPSCs) differentiation, proliferation, and activity, and subsequent tissue activation. However, many unclear points still remain regarding the mechanisms of action induced by PBMT in REPs. Therefore, in this review, we present the applications of laser and PBMT irradiation to the procedures of REPs and in endodontics. In addition, the effects of PBMT on the regenerative processes of hDPSCs are reviewed from biochemical and cytological perspectives on the basis of the available literature. Furthermore, we consider the feasibility of treatment in which PBMT irradiation is applied to stem cells, including dental pulp stem cells, and we discuss research that has reported on its effect. Full article

Interesting photobiological properties have been demonstrated for some Cachrys species, including C. libanotis L., C. sicula L., and C. pungens Jan. The present study was designed to assess the photocytotoxic activity of Prangos ferulacea Lindl. (synonym of C. ferulacea (L.) Calest.). This plant was previously considered a Cachrys species but, at present, it is part of the Prangos genus. P. ferulacea is an orophilous plant present in the eastern Mediterranean and in western Asia. Three different extraction techniques were utilized. Obtained extracts were compared both for their phytochemical content and for their photobiological properties on human melanoma cells irradiated with UVA light. The apoptotic responses, together with the antioxidant activity, were also assessed. P. ferulacea extracts were able to affect cell viability in a concentration-dependent manner, with the sample obtained through supercritical CO₂ extraction showing the highest activity (IC₅₀ = 4.91 μg/mL). This research points out the interesting content in the photoactive compounds of this species, namely furanocoumarins, and could provide a starting point for further studies aimed at finding new photosensitizing agents useful in cancer photochemotherapy. Full article