Search Results (349)

Background/Objectives: The increased prevalence of multidrug-resistant Escherichia coli and carbapenemase-producing Enterobacteriaceae poses a critical threat to global health and food safety. Antimicrobial Blue Light (aBL) in the 400–470 nm spectrum has emerged as a promising, chemical-free disinfection strategy that targets intracellular porphyrins and flavins to induce oxidative stress. However, the influence of wavelength, dosimetry, and environmental stressors on endogenous photoinactivation remains poorly standardized regarding optical parameters and biological exposure protocols. This systematic review aimed to evaluate the antimicrobial efficacy of pure blue light (400–470 nm) against E. coli across various phenotypes and environmental conditions, excluding the use of exogenous photosensitizers. Methods: PubMed, Scopus, and Web of Science were searched for studies that utilized 400–470 nm light as an antimicrobial agent against E. coli. Data extraction focused on spectral efficiency, total fluence (J/cm²), and log₁₀ reduction. The Risk of Bias was assessed using an adapted Office of Health Assessment and Translation tool for in vitro studies. Results: Synthesis of 11 high-quality studies indicated that wavelengths near 405 nm have the highest germicidal efficiency due to the Soret band absorption of endogenous porphyrins. Efficacy is highly dose-dependent: significant log₁₀ reductions were achieved in planktonic cells, although biofilms required substantially higher fluences. Sub-lethal environmental stressors such as acidic pH, high salinity, and thermal fluctuations demonstrated a synergistic effect, which significantly enhanced the rate of photoinactivation. Multidrug-resistant and carbapenemase-producing Enterobacteriaceae strains showed similar susceptibility to aBL relative to antibiotic-sensitive strains, suggesting no cross-resistance between light and traditional drugs. Conclusions: Endogenous blue light is a highly effective, non-thermal technology for E. coli decontamination. Its efficacy is modulated by the interplay between optical parameters and environmental conditions. These findings provide a framework for the development of standardized protocols for applying aBL to clinical wound care and food industry use cases. They also highlight the potential of aBL as a critical tool in the post-antibiotic era. This systematic review was registered in the International prospective register of systematic reviews (PROSPERO) under protocol CRD420261331871. Full article

Antimicrobial photodynamic therapy is a method that utilizes photodynamic inactivation of microorganisms exposed to a photosensitizer irradiated by a specific wavelength, followed by the formation of reactive oxygen species and subsequent oxidative stress. In contrast to antibiotics, which are generally efficient against specific microorganisms, photodynamic inactivation exhibits efficacy against a wide range of bacteria, representing a promising and non-invasive alternative to treating infections caused by pathogens of different origins. This study compares the antibacterial efficacy of five different photosensitizers, including TMPyP, Protoporphyrin IX, PdTPPS₄, Methylene Blue, and ZnPCS₂, against eight representatives of various pathogens, including Gram-negative bacteria Escherichia coli, Pseudomonas aeruginosa, Gram-positive bacteria Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, Enterococcus faecium, MRSA and Bacillus subtilis. An optimal irradiation protocol was developed based on growth curve measurements involving double irradiation. To induce the photodynamic effect, we utilized LED emitters with wavelengths of 414 nm and 660 nm, chosen to align with the photophysical properties of the photosensitizers. Additionally, the research included assessments of the radiation’s phototoxicity and the photosensitizers’ dark toxicity against specific microorganisms. The optical properties of the photosensitizers were analyzed using absorption spectrophotometry. The effectiveness of photodynamic inactivation was assessed by determining the minimum inhibitory and bactericidal concentrations. This study aimed to identify the most suitable photosensitizer for clinical application, considering the toxicity of the photosensitizer, the radiant exposure, and its efficacy in photodynamic inactivation. Full article

Gold nanoparticles offer a versatile platform for cancer theranostics because their high atomic number can enhance X-ray energy deposition, their plasmonic properties support photothermal and photoacoustic applications, and their surfaces allow drug loading and molecular targeting. However, therapeutic benefit remains heterogeneous because tumor uptake, intratumoral coverage, and subcellular localization determine whether deposited gold can be converted into biologically effective damage. Redox context further shapes this conversion by determining whether AuNP-triggered physical or catalytic events can overcome local buffering and propagate into durable injury. During radiotherapy, AuNPs increase local secondary electron release and ROS formation, which can intensify DNA damage when GSH-dependent peroxide detoxification, thioredoxin-related buffering, and KEAP1-NRF2-regulated antioxidant responses are insufficient to contain the redox burden. In catalytic systems, Au-containing nanozymes can convert endogenous H₂O₂ into highly reactive radicals and may simultaneously deplete glutathione, thereby amplifying mitochondrial dysfunction and lipid peroxidation. During photoactivation, plasmonic heating and photosensitizer coupling further reshape ROS generation in a time-dependent and location-dependent manner. On the diagnostic side, CT or spectral CT can quantify tumor gold burden and coverage, whereas ROS-responsive photoacoustic, SERS, or fluorescence probes can report treatment-related oxidants and verify whether redox activation has occurred within the tumor. Clinical translation will therefore depend on quantification-guided dosing, definition of spatial coverage and activation timing, standardized redox-response readouts, and long-term safety evaluation. Full article

Ninety-five structurally diverse chemically synthesized compounds, retrieved from the chemical library of the national research infrastructure OPENSCREEN-GR, were subjected here to a structure-agnostic bioactivity-driven screen focused on putative anti-cancer activities using a number of human cell lines derived from diverse types of cancer. Interestingly, the top four compounds that displayed a broad anti-cancer activity (with no apparent photosensitizing activity) during unbiased biological evaluation were then identified as phenoxazine derivatives. In addition to their cytotoxic activity, phenoxazine derivatives BS115 and ST61 were also found to be cytostatic by inducing a p53-independent G2/M cell cycle arrest as well as a G0/G1 arrest only in cells harboring a functional p53. A kinetics analysis using two multiplex immunoassays and siRNA-mediated knockdown of HSP27 revealed that the latter protein is a key molecule in the response of cancer cells to ST61 via its phosphorylation by p38 MAPK. The main mechanism underlying ST61’s anti-cancer activity was found to involve oxidative stress, as scavenging of ST61-induced reactive oxygen species by N-acetyl-cysteine led to the abrogation of the compound’s cytotoxic effect. Full article

Despite the demand for personalized wound care, integrating diagnostics and therapeutics into a unified platform remains a significant challenge. To address this, we developed a 3D-printed theranostic hydrogel using vat photopolymerization, enabling precise, multifunctional wound management. The hydrogel matrix, composed of poly(acrylamide-co-hydroxyethyl acrylate) and carboxymethyl cellulose, was chemically crosslinked with poly(ethylene glycol) diacrylate. Bromocresol purple was integrated into the photosensitive resin to enhance printing fidelity and serve as a diagnostic indicator, providing a distinct colorimetric shift upon skin infection. For controlled drug delivery, graphene oxide (GO) and levofloxacin were incorporated into the system. The 3D-printed hydrogel demonstrated superior swelling capacity (>600%), ideal for absorbing wound exudate. A semi-quantitative linear colorimetric response was observed across varying pH levels, allowing for clear differentiation between healthy healing skin (pH 4.0–6.0) and infected conditions (pH 7.0 and above). Furthermore, the hydrogel exhibited infection-stimulated therapy, with a cumulative levofloxacin release of 92.63% at pH 8, significantly higher than in acidic conditions. Moreover, the incorporation of GO further optimized the delivery profile by tuning absorption and release rates. Synergizing real-time monitoring and on-demand therapeutic action, this 3D-printed system offers a scalable, robust solution for future-ready, personalized wound management. Full article

Background and Objectives: Burn wounds are associated with delayed healing, infection, and pathological scarring. Effective repair requires tightly regulated immune and oxidative stress responses, including macrophage polarization. This study evaluated the association of the photosensitizer Rose Bengal, delivered in a hydrogel vehicle, with macrophage polarization and oxidative stress after burn injury. Materials and Methods: Three female red Duroc pigs underwent full-thickness contact burns followed by excision and autografting. Wounds received 20% Pluronic F-127 hydrogel containing 0.1% Rose Bengal sodium, hydrogel alone, or PBS (phosphate-buffered saline) on days 1, 7, and 14 post-burn. Biopsies from days 7 and 120 were analyzed by immunohistochemistry for pan-macrophage marker, CD206 (M2 macrophages), CD3E (T-cell infiltration), and 4-hydroxynonenal (4-HNE; oxidative stress marker). Mean fluorescence intensity was analyzed using two-way ANOVA with Tukey’s post hoc test (mean ± SD, p < 0.05). Results: At day 120, Rose Bengal treatment showed higher pan-macrophage expression (0.80 ± 0.07) compared with PBS (0.62 ± 0.10; p = 0.0034), whereas the difference versus hydrogel (0.68 ± 0.07; p = 0.0628) was not significant. CD206 expression was similarly higher in Rose Bengal-treated wounds (0.77 ± 0.06) compared with PBS (0.62 ± 0.05; p = 0.0277); hydrogel also differed from PBS (p = 0.0287), without a difference between hydrogel and Rose Bengal. For CD3E, a significant main effect of treatment was observed (F(2,12) = 8.346, p = 0.0054), with lower values in Rose Bengal versus PBS at day 120 (p = 0.0360). No differences in 4-HNE were detected. Conclusions: Rose Bengal–hydrogel treatment was associated with increased macrophage presence and enhanced M2 polarization without increased T-cell infiltration. Effects were significant versus PBS but not hydrogel, suggesting Rose Bengal may contribute to a pro-regenerative immune microenvironment without excessive adaptive activation. Full article

Daily exposure to blue light emitted by digital devices has raised concerns about oxidative stress-mediated damage to the ocular surface. Despite growing interest, validated in vitro models to study blue light-induced oxidative stress in corneal epithelial cells remain limited. A reproducible in vitro method was developed using rabbit corneal epithelial (RCE) cells exposed to blue LED light (405 nm). Irradiation parameters were optimized to induce oxidative stress without causing overt cytotoxicity. Cellular viability, intracellular ROS production, and mitochondrial oxidative stress were assessed. The model was validated using reference antioxidants (ascorbic acid and oleuropein), oleuropein formulated in a drug-in-cyclodextrin-in-liposome system (OLE-DCL), and two commercial ophthalmic formulations applied before or after irradiation. Blue light irradiation at 4.57 W/m² for 30 min significantly increased intracellular and mitochondrial ROS levels while preserving cell viability, indicating sublethal photo-oxidative stress. Ascorbic acid effectively suppressed ROS generation, whereas free oleuropein showed reduced efficacy, likely due to photosensitivity. OLE-DCL significantly enhanced antioxidant activity under irradiation. The model also discriminated between protective and restorative treatment strategies. This study establishes a validated in vitro blue light-induced oxidative stress model for corneal epithelial cells, suitable for screening antioxidant compounds, formulations, and application strategies relevant to ocular surface protection. Full article

Hypocrellin A (HA) represents a pharmaceutically important perylenequinone photosensitizer produced by Shiraia bambusicola. However, submerged fermentation remains constrained by filamentous morphological characteristics and inherent mass transfer limitations. Although microparticle-enhanced cultivation (MPEC) has demonstrated efficacy in filamentous fungal systems, the molecular mechanisms by which physical cues, such as microparticle-induced shear stress, reprogram fungal metabolism remain largely unexplored. This work systematically optimizes SiO₂-based MPEC parameters for S. bambusicola GDMCC 60438, including particle dimensions, temporal addition protocols, and solid loading. Mechanistic investigations integrated pellet morphology analysis, membrane lipid composition, intracellular redox status, energy/precursor markers, and RNA-seq transcriptomic profiling with qRT-PCR validation. Under optimized conditions (10% w/v SiO₂, 30 mesh, added at 6 h), HA yield reached 41.76 ± 5.02 mg/L, representing a 3.65-fold increase over controls. MPEC shifted morphology toward smaller, more porous pellets with denser internal structure, accompanied by increased membrane fluidity (unsaturated/saturated fatty acid ratio from 1.54 to 2.63), elevated ROS levels with antioxidant enzyme activation, and enhanced acetyl-CoA and ATP accumulation. Transcriptomic analysis identified 206 differentially expressed genes enriched in oxidative phosphorylation, carbon metabolism, and stress responses, with upregulation of PKS-related biosynthetic genes and major facilitator superfamily transporters. This work establishes an integrated mechanistic framework linking particle-induced morphological changes to metabolic reprogramming through oxidative stress and subsequent transcriptional activation of the HA biosynthetic pathway, providing rational design principles for MPEC strategies in filamentous fungi. Full article

Our recent work has focused on red light-mediated photoreduction of p-benzoquinones and both o-, and p-naphthoquinones using methylene blue and the chlorophyll metabolite, pheophorbide A as photosensitizers. Photoreduction of biologically relevant quinones mimics photoreduction of plastoquinone by chlorophyll in photosynthesis. We examined photo-oxidation and photoreduction reactions of catechols because their oxidation to o-quinones by reactive oxygen species is implicated in protein damage in neurodegeneration. Photo-oxidation of catecholamines including dopamine, epinephrine and norepinephrine required red light, methylene blue or pheophorbide A, and molecular oxygen. Their cyclized oxidation products, aminochrome, adrenochrome and noradrenochrome, were detected by UV/visible spectroscopy. Hydrogen peroxide was generated during photo-oxidation by singlet oxygen-dependent oxidation of catecholamines. Inclusion of tertiary amine electron donors decreased cyclized products but did not affect hydrogen peroxide yield consistent with concurrent photo-oxidation followed by photoreduction of the o-quinone intermediate. Unreacted dopamine and norepinephrine were quantified using 3-hydroxyphenyl boronic acid following photochemical reactions. Dopamine and norepinephrine boronate esters absorb at 417 and 550 nm. Photo-oxidation of dihydroxycaffeic acid and dihydroxyphenyl acetic acid was also evaluated by detecting their boronate esters at 475 nm. We hypothesize that photoreduction of transient o-quinones by the combination of red light and dietary chlorophyll metabolites may be a path to limit protein damage and to recycle catechol antioxidants. Full article

PrFeTiO₃ perovskite composite was synthesized, and its structural, morphological, chemical, and optical properties were comprehensively characterized. X-ray diffraction (XRD) and a selected area electron diffraction (SAED) confirm the formation of an orthorhombic distorted perovskite phase with no secondary impurities. Transmission electron microscope (TEM) observations show aggregated nanocrystalline domains, while EDS mapping reveals homogeneous cation distribution (Pr, Fe, Ti, O), confirming successful incorporation of Fe and Ti into the perovskite lattice. X-ray photoelectron spectroscopy (XPS) analysis identifies Pr³⁺, Fe³⁺, and Ti⁴⁺ as the dominant oxidation states, supporting charge-compensated B-site substitution. Optical analysis reveals a bandgap of ~2.0 eV, significantly narrower than pristine titanates, indicating enhanced visible-light absorption. This multi-modal characterization verifies the successful formation of PrFeTiO₃ and highlights its potential as a visible-light-active photocatalyst. Although PrTiO₃ showed little reactivity to visible light, PrFeTiO₃ showed excellent efficiency in visible light photocatalytic reactions. PrFeTiO₃ showed more than 20 times better performance than PrTiO₃ in the photodegradation of methylene blue in the liquid phase and formaldehyde in the gas phase. Furthermore, PrFeTiO₃ showed more than 95% superior bactericidal activity against the pathogenic bacterium Staphylococcus aureus than PrTiO₃. Its high photocatalytic efficiency can be attributed to its strong photosensitivity to visible light and small band gap energy. Full article

Photodynamic therapy (PDT) is a promising localized strategy for the treatment of cervical cancer, ranking as the fourth most common cancer among women worldwide. The integration of photosensitizers (PSs) in localized drug delivery systems (DDSs), particularly in electrospun nanofibers, holds tremendous potential to overcome the drawbacks of their systemic administration. Exploring multilayer fibrous architectures provides a versatile therapeutic platform to design the next generation of localized DDS. In this work, localized implants for cancer treatment using PDT were developed using polyhydroxyalkanoate (PHA), chitosan (CS) and polyethylene oxide (PEO) as biopolymers and a porphyrin (Por) as PS, following two approaches: blended PHA/Por electrospun microfibers and multilayered membranes (PHA–Por/CS/PEO) produced by sequential electrospinning. The synthesized Por displayed higher cytotoxicity in light compared to dark against tumor cells. All the developed membranes were characterized regarding their morphology, wettability, absorption and fluorescence properties. PHA–Por membranes exhibited overall uniform fibrous morphologies with successful Por incorporation. Nonetheless, they presented a highly hydrophobic surface, compromising the Por release and cell–material interactions. In contrast, multilayer PHA–Por/CS/PEO membranes demonstrated enhanced hydrophilicity and enabled sustained Por release. Upon light irradiation, these membranes induced a significantly greater inhibition of HeLa cell proliferation (29.61%) compared to dark conditions (6.21%), confirming their photodynamic activity. Full article

This work investigated the structural, morphological, electrical and photovoltaic properties of n-ZnNiO/p-Si heterostructures. ZnNiO nanocomposite thin films were fabricated on p-Si (100) substrates using pulsed laser deposition, enabling the formation of n-type oxide/p-type silicon heterojunctions. The crystalline structure and surface morphology of the deposited thin films were examined using X-ray diffraction and scanning electron microscopy, revealing well-defined crystalline features and uniform surface morphology. The electrical characteristics were analyzed through current–voltage measurements, allowing the extraction of key diode parameters. In addition, the optoelectronic response under ultraviolet illumination was investigated, demonstrating pronounced photosensitivity in the UV spectral range. Several important electrical and optoelectronic parameters relevant to ultraviolet photodetection were determined and discussed. The obtained results indicate that ZnNiO-based heterostructures combined with silicon substrates constitute a promising material platform for advanced optoelectronic and ultraviolet applications. Full article

Analogs of tricyclic thiopurine nucleosides combine structural features of endogenous DNA adducts with efficient photosensitizing chromophores, making them valuable models for studying nucleic acid damage induced by reactive oxygen species (ROS). In this work, we investigate the photochemical properties of two tricyclic guanosine derivatives, 9-thio-1,N²-ethenoguanosine and 6-methyl-9-thio-1,N²-ethenoguanosine, under UVA irradiation. We characterize their excited-state behavior, their ability to generate singlet oxygen (¹O₂) and superoxide radicals (O₂^●−), and the resulting oxidative transformation pathways. Both compounds are photochemically stable under anaerobic conditions but undergo efficient oxygen-dependent phototransformation, yielding a diverse set of oxidative and dimeric photoproducts. Product analysis reveals that singlet oxygen mediates desulfurization, ring opening, and extensive sulfur oxidation, whereas radical pathways involving superoxide lead exclusively to dimer formation. Importantly, the triplet excited states of these tricyclic thiopurines are not quenched by natural nucleosides, allowing both Type I and Type II photosensitizing pathways to operate in nucleic-acid-like environments. These results provide molecular-level insight into ROS-induced purine damage and highlight tricyclic thiopurines as effective photosensitizers of oxidative DNA and RNA damage. Full article

Singlet oxygen (¹O₂), the excitation stage of the ground-state molecular oxygen, is a fundamental reactive oxygen species (ROS) with important functions in plant growth, development, and stress responses. In plant cells, ¹O₂ is mainly generated in the chloroplast due to photosensitizing activity of tetrapyrroles. Moreover, ¹O₂ can be generated in non-photosynthetic tissues when plants suffer environmental stresses. Although ¹O₂ was initially considered as a cytotoxin—causing merely photooxidative damages, more recent work suggests that ¹O₂ also acts as a signal that either triggers a programmed cell death response or promotes acclimation. The ¹O₂ signaling pathway is distinct and operates independently of other ROS signaling cascades. In Arabidopsis, EXECUTER1 (EX1) protein has been identified as a crucial signaling component that perceives and relays ¹O₂ signals to the nucleus, thereby initiating extensive transcriptional reprogramming. Additionally, oxidative products of carotenoids, such as β-cyclocitral, are also recognized as ¹O₂-derived signaling molecules. Through specific chloroplast-to-nucleus signaling and cross talk with hormone signaling networks—including jasmonic acid (JA) and salicylic acid (SA)—¹O₂ helps finely coordinate plant growth, defense responses, and cell fate decisions under fluctuating environmental conditions. This review aims to summarize current knowledge on ¹O₂ generation and signaling, ¹O₂-induced chloroplast changes under diverse stress conditions, and cross talk between ¹O₂ and phytohormone signaling. Full article

This study aimed to develop natural, safe, and effective antimicrobial packaging materials for extending the shelf life of chilled pork during refrigeration. Emodin-chitosan (Em-Cs) composite films with varied concentrations were developed by combining the casting method with photodynamic inactivation technology, utilizing chitosan as the matrix and emodin as the functional photosensitizer for active packaging. The optical, mechanical, and barrier properties of the composite films were examined. The inhibitory effects of the samples on Escherichia coli, Salmonella Derby, Staphylococcus aureus, and Pseudomonas fragi under 450 nm blue light irradiation were evaluated. The results demonstrated that the Em-Cs composite film exhibited excellent transparency, mechanical strength, and water barrier properties, with good compatibility between emodin and chitosan. Under light irradiation, the composite film generates reactive oxygen species (ROS), whose bactericidal efficacy depends on the concentration of emodin and the duration of light exposure. When applied to chilled pork packaging, this composite film inhibited bacterial growth within the meat for 10 days, effectively retarding pH increase, lipid oxidation, and volatile basic nitrogen accumulation. The present study proposes a novel methodology for the application of photodynamic technology in the context of food preservation, and it presents a new type of natural antimicrobial packaging material for the preservation of chilled pork. Full article