New photosensitizers for photodynamic therapy

Novel tris-bipyridine based Ru(II) complexes as type-I/-II photosensitizers for antitumor photodynamic therapy through ferroptosis and immunogenic cell death

Ru(II) complexes have attracted attention as photosensitizers for their promising photodynamic properties. Herein, novel tris-bipyridine based Ru(II) complexes (6a-e) were synthesized by introducing saturated heterocycles to improve photodynamic properties and lipid-water partition coefficients. Among them, 6d demonstrated significant phototoxicity towards three cancer cells, with IC50 values of 5.66-7.17 μM, exceeding values in dark (IC50s > 100 μM). Under hypoxic conditions, 6d maintained excellent photodynamic activity in A549 cells, with PI values exceeding 24, highlighting its potential for highly effective type-I/-II photodynamic therapy by inducing ROS generation, oxidative stress, and mitochondrial damage. Additionally, it induced ferroptosis and immunogenic cell death of A549 cells by regulating the expression of relevant markers. Finally, 6d remarkably inhibited the growth of A549 transplanted tumor growth by 95.4 %. This Ru(II) complex shows great potential for cancer treatment with its potent photodynamic activity and diverse mechanisms of tumor cell death.

Photodynamic therapy: An emerging therapeutic modality in dentistry

Photodynamic Therapy (PDT) is a rapidly evolving, non-invasive treatment modality with considerable promise in dental pharmacotherapeutics. This review article comprehensively examines PDT, beginning with its principles and then delving into its diverse applications in dentistry, including periodontal disease, endodontics, oral cancer, dental implants, and dental caries. Each area presents the latest research and discusses the potential benefits and challenges. The unique advantages of PDT are highlighted, such as selective targeting, broad-spectrum antimicrobial effect, lack of resistance development, and its synergistic effect with other treatments. However, challenges such as photosensitizer delivery, light penetration, oxygen availability, and the need to standardize protocols are also acknowledged. The review further explores future perspectives of PDT in dentistry, including advancements in photosensitizer design, overcoming hypoxic limitations, personalized protocols, integration with other therapies, and standardization and regulation. The potential of advanced technologies, such as nanotechnology and synthetic biology, to improve PDT outcomes is also discussed. The review concludes that while PDT has shown immense potential to revolutionize dental pharmacotherapeutics, further high-quality research is needed to translate this potential into everyday dental practice. The promising future of PDT in dentistry suggests a more effective and less invasive treatment option for a range of dental conditions.

Enhanced Photodynamic Therapy for Neurodegenerative Diseases: Development of Azobenzene-Spiropyran@Gold Nanoparticles for Controlled Singlet Oxygen Generation

The development of durable photosensitizers is pivotal for advancing phototherapeutic applications in biomedicine. Here, we introduce a core-shell azobenzene-spiropyran structure on gold nanoparticles, engineered to enhance singlet oxygen generation. These nano-photosensitizers exhibit increased structural stability and thermal resistance, as demonstrated by slowed O-N-C bond recombination dynamics via in-situ Raman spectroscopy. Notably, the in-situ formation of merocyanine and a light-induced compact shell arrangement extend its half-life from 47 minutes to over 154 hours, significantly boosting singlet oxygen output. The nano-photosensitizer also shows high biocompatibility and notably inhibits tau protein aggregation in neural cells, even with phosphatase inhibitors. Further, it promotes dendritic growth in neuro cells, doubling typical lengths. This work not only advances chemical nanotechnology but also sets a foundation for developing long-lasting phototherapy agents for treating neurodegenerative diseases.

Photodynamic therapy using hybrid nanoparticles comprising of upconversion nanoparticles and chlorin e6-bearing pullulan

With its minimal invasiveness, photodynamic therapy (PDT) is considered one of the most elegant modalities in cancer treatment. In this study, a facile hybrid nanoparticle was developed, composed of upconversion nanoparticles and chlorin e6-bearing pullulan, which can serve as a photosensitizer activated by a near-infrared red laser. Cell death induction in cancer cells was achieved through energy transfer from the near-infrared red laser emitted by the upconversion nanoparticles to chlorin e6. The therapeutic efficacy of our hybrid system surpassed that of the clinically available photosensitizer, Photofrin, and hybrid liposomes comprising upconversion nanoparticles and chlorin e6 were employed as control. Accumulation of our system in tumor tissue in tumor xenograft mice was primarily achieved through the enhanced permeability and retention (EPR) effect. The administered hybrids were excreted from each organ within 21 days after administration, minimizing the risk of undesirable side effects. Notably, our system exhibited 400 times higher PDT activity in tumor-bearing mice compared to the control groups. It also effectively inhibited metastasis.

In vitro antibacterial activity of photoactivated flavonoid glycosides against Acinetobacter baumannii

Acinetobacter baumannii's extensive antibiotic resistance makes its infections difficult to treat, so effective strategies to fight this bacterium are urgently needed. This study aims to evaluate the effectiveness of antimicrobial photodynamic therapy (aPDT) mediated by Rutin-Gal(III) complex and Quercetin against A. baumannii. Absorbance spectra, fluorescence spectra, and minimum inhibitory concentration (MIC) of Rutin-Gal(III) complex and Quercetin were determined. The intracellular reactive oxygen species (ROS), extracellular polymeric substances (EPS), cell membrane permeability, expression of ompA and blaOXA-23, anti-biofilm activity, and anti-metabolic activity of Rutin-Gal(III) complex- and Quercetin-mediated aPDT were measured. Rutin-Gal(III) complex and Quercetin revealed absorption peaks in the visible spectra. Quercetin and Rutin-Gal(III) complex displayed fluorescence peaks at 524 nm and 540 nm, respectively. MIC values for the Rutin-Gal(III) complex and Quercetin were 64 µg/mL and 256 µg/mL, respectively. Quercetin- and Rutin-Gal(III) complex-mediated aPDT significantly reduced the colony forming units/mL (58.4% and 67.5%), EPS synthesis (47.4% and 56.5%), metabolic activity (30.5% and 36.3%), ompA (5.5- and 10.5-fold), and blaOXA-23 (4.1-fold and 7.8-fold) genes expression (respectively; all P < 0.05). Quercetin- and Rutin-Gal(III) complex-mediated aPDT enhanced notable biofilm degradation (36.2% and 40.6%), ROS production (2.55- and 2.90-folds), and membrane permeability (10.8- and 9.6-folds) (respectively; all P < 0.05). The findings indicate that Rutin-Gal(III) complex- and Quercetin-mediated aPDT exhibits antibacterial properties and could serve as a valuable adjunctive strategy to conventional antibiotic treatments for A. baumannii infections. One limitation of this study is that it was conducted solely on the standard strain; testing on clinical isolates would allow for more reliable interpretation of the results.

Fluorinated High-Valent Sn(IV) Porphyrins Show Remarkable Photodynamic Activity in Cancer Cells

In recent years, Sn(IV) porphyrins have proven to be excellent choice as photosensitizers for photodynamic therapy. This work reports the synthesis, characterization and photodynamic activity of four high-valent fluorinated Sn(IV) porphyrins having different numbers of F-atoms in the peripheral of meso-phenyl groups viz. (Dichloro)meso-tetrakis(4-fluorophenylporphyrinato)stannic(IV), [Sn(IV)FTPP(Cl)2] or Sn1; (Dichloro)meso-tetrakis(2,4-difluorophenylporphyrinato)stannic(IV), [Sn(IV)2,4-FTPP(Cl)2] or Sn2; (Dichloro)meso-tetrakis(2,6-difluorophenylporphyrinato)stannic(IV), [Sn(IV)2,6-FTPP(Cl)2] or Sn3 and (Dichloro)meso-tetrakis(4-trifluoromethylphenylporphyrinato)stannic(IV), [Sn(IV)CF3TPP(Cl)2] or Sn4. The solid-state structure of Sn1 has been determined by single crystal X-ray diffraction analysis. The increasing number of F-atoms attached to the meso-phenyl positions of the porphyrin framework results in increase of their lipophilicity, singlet oxygen quantum yield (ΦΔ) and photocytotoxicity in A549 (human lung adenocarcinoma cells), MCF-7 and MDA-MB-231 (human breast adenocarcinoma) cells. Sn4 predominantly localize in the mitochondria of A549 cells. The light-induced cell death by the Sn(IV) porphyrins in A549 cells occur primarily via apoptosis.

Advances and perspectives in use of semisolid formulations for photodynamic methods

Although nearly 30 years have passed since the introduction of the first clinically approved photosensitizer for photodynamic therapy, progress in developing new pharmaceutical formulations remains unsatisfactory. This review highlights that despite years of research, many recurring challenges and issues remain unresolved. The paper includes an analysis of selected essential studies involving aminolevulinic acid and its derivatives, as well as other photosensitizers with potential for development as medical products. Among various possible vehicles, special attention is given to gelatin, alginates, poly(ethylene oxide), polyacrylic acid, and chitosan. The focus is particularly on infectious and cancerous diseases. Key aspects of developing new semi-solid drug forms should prioritize the creation of easily manufacturable and biocompatible preparations for clinical use. At the same time, new formulations should preserve the primary function of photosensitizers, which is the generation of reactive oxygen species capable of destroying pathogenic cells or tumors. Additionally, the use of adjuvant properties of carriers, which can enhance the effectiveness of macrocycles, is emphasized, especially in chitosan-based antibacterial formulations. Current research indicates that many promising dyes and macrocyclic compounds with high potential as photosensitizers in photodynamic therapy remain unexplored in formulation and development work. This review outlines potential new and previously explored pathways for advancing photosensitizers as active pharmaceutical ingredients (APIs).

Biotechnological advances in microbial synthesis of gold nanoparticles: Optimizations and applications

This review discusses the eco-friendly and cost-effective biosynthesis of gold nanoparticles (AuNPs) in viable microorganisms, focusing on microbes-mediated AuNP biosynthesis. This process suits agricultural, environmental, and biomedical applications, offering renewable, eco-friendly, non-toxic, sustainable, and time-efficient methods. Microorganisms are increasingly used in green technology, nanotechnology, and RNAi technology, but several microorganisms have not been fully identified and characterized. Bio-nanotechnology offers eco-friendly and sustainable solutions for nanomedicine, with microbe-mediated nanoparticle biosynthesis producing AuNPs with anti-oxidation activity, stability, and biocompatibility. Ultrasmall AuNPs offer rapid distribution, renal clearance, and enhanced permeability in biomedical applications. The review explores nano-size dependent biosynthesis of AuNPs by bacteria, fungi, and viruses revealing their non-toxic, non-genotoxic, and non-oxidative properties on human cells. AuNPs with varying sizes and shapes, from nitrate reductase enzymes, have shown potential as a promising nano-catalyst. The synthesized AuNPs, with negative charge capping molecules, have demonstrated antibacterial activity against drug-resistant Pseudomonas aeruginosa, and Acinetobacter baumannii strains, and were non-toxic to Vero cell lines, indicating potential antibiotic resistance treatments. A green chemical method for the biosynthesis of AuNPs using reducing chloroauric acid and Rhizopus oryzae protein extract has been described, demonstrating excellent stability and strong catalytic activity. AuNPs are eco-friendly, non-toxic, and time-efficient, making them ideal for biomedical applications due to their antioxidant, antidiabetic, and antibacterial properties. In addition to the biomedical application, the review also highlights the role of microbially synthesized AuNPs in sustainable management of plant diseases, and environmental bioremediation.

Photodisinfection of Alphaherpesvirus 1 in bovine semen

Reproductive biotechnologies are widely consolidated as a methodology in cattle breeding and have an important impact on the genetic improvement of cattle herds. Semen is an important source of dissemination of pathogenic microorganisms during reproductive procedures. To ensure the sanitary quality of the semen, it is essential to consider the presence of various microorganisms including viruses. One of the main viral agents of reproductive interest is Bovine Alphaherpesvirus 1 (BoHV-1), the etiological agent responsible for bovine rhinotracheitis and vulvovaginitis and frequently associated with reproductive efficiency of matrices and bulls. In artificial insemination centers, semen treatment is generally based only on the use of antibiotics, ignoring the possibility of inactivating other non-bacterial infectious agents. In this context, photodisinfection emerges as a promising alternative to inactivate a wide range of microorganisms, offering a complementary or substitution approach to those conventional semen treatment methods. In this work, we evaluated the use of four halogenated sulfonated porphyrins as potential photosensitizers (PSs) for photodynamic inactivation of Bovine Alphaherpesvirus I (BoHV-1) for bovine semen disinfection. The PSs were synthesized and photophysical parameters, such as UV-Vis absorption spectra and singlet oxygen quantum yield (ΦΔ) were presented. Photoinactivation of BoHV-1 was first shown in cell culture and then confirmed in artificially infected bovine semen and then the phototoxicity of PSs against spermatozoa was evaluated. All PSs were effective in BoHV-1 inactivation; however, the photosensitizer containing two chlorine atoms, showed to be more efficient due to the shorter time required for complete viral inactivation. The slight alterations in sperm kinetics were observed, but remained within those acceptable by regulatory agencies for animal reproduction. Although the methodology used in this work only included bovine semen, we emphasize that the proposed photodisinfection methodology can be adapted and applied to a wide range of biological materials and microorganisms of animal or human interest.

Demystifying the management of cancer through smart nano-biomedicine via regulation of reactive oxygen species

Advancements in therapeutic strategies and combinatorial approaches for cancer management have led to the majority of cancers in the initial stages to be regarded as treatable and curable. However, certain high-grade cancers in the initial stages are still regarded as chronic and difficult to manage, requiring novel therapeutic strategies. In this era of targeted and precision therapy, novel strategies for targeted delivery of drug and synergistic therapies, integrating nanotherapeutics, polymeric materials, and modulation of the tumor microenvironment are being developed. One such strategy is the study and utilization of smart-nano biomedicine, which refers to stimuli-responsive polymeric materials integrated with the anti-cancer drug that can modulate the reactive oxygen species (ROS) in the tumor microenvironment or can be ROS responsive for the mitigation as well as management of various cancers. The article explores in detail the ROS, its types, and sources; the antioxidant system, including scavengers and their role in cancer; the ROS-responsive targeted polymeric materials, including synergistic therapies for the treatment of cancer via modulating the ROS in the tumor microenvironment, involving therapeutic strategies promoting cancer cell death; and the current landscape and future prospects.

Biocompatible Zn-Phthalocyanine/Gelatin Nanofiber Membrane for Antibacterial Therapy

In this study, the fabrication and characterization of Zn-phthalocyanine/gelatin nanofibrous membranes is reported using the electrospinning technique. The membranes exhibit a homogeneous distribution of Zn-phthalocyanine within the gelatin matrix, maintaining the structural integrity and photosensitizing properties of the phthalocyanine. Scanning electron microscopy revealed that the electrospun fibers possess diameters ranging results as 100-300, 200-700, and 300-800 nm for Gel, ZnPc/Gel 1, and ZnPc/Gel 2, respectively. The addition of ZnPc does not decrease the hydrophilicity of the Gel membrane. The nanofibrous membranes showed good cytocompatibility, as indicated by the high viability of Vero cells exposed to membrane extracts. Furthermore, these composites supported cell adhesion and proliferation on their surfaces. The two Zn-phthalocyanine/gelatin nanofiber formulations exhibited significant antimicrobial activity toward Escherichia Coli (E. Coli) and Staphylococcus Aureus (S. Aureus) under visible light illumination, achieving reductions of 3.4 log10 and 3.6 log10 CFU mL-1 for E. coli, and 3.9 log10 and 4.1 log10 CFU mL-1 for S. aureus. These results demonstrate the potential of Zn-phthalocyanine/gelatin nanofibrous membranes as effective agents in antibacterial photodynamic therapy, providing a promising solution to control bacterial infections and antibiotic resistance.

Development of a small molecule-based two-photon photosensitizer for targeting cancer cells

Photodynamic therapy (PDT) employing two-photon (TP) excitation is increasingly recognized to induce cell damage selectively in targeted areas, underscoring the importance of developing TP photosensitizers (TP-PSs). In this study, we developed BSe-B, a novel PS that combines a selenium containing dye with biotin, a cancer-selective ligand, and is optimized for TP excitation. BSe-B demonstrated enhanced cancer selectivity, efficient generation of type-I based reactive oxygen species (ROS), low dark toxicity, and excellent cell-staining capability. Evaluation across diverse cell lines (HeLa, A549, OVCAR-3, WI-38, and L-929) demonstrated that BSe-B differentiated and targeted cancer cells while sparing normal cells. BSe-B displayed excellent in vivo biocompatibility. In cancer models such as three-dimensional spheroids and actual colon cancer tissues, BSe-B selectively induced ROS production and cell death under TP irradiation, demonstrating precise spatial control. These findings highlight the potential of BSe-B for imaging-guided PDT and its capability for micro treatment within tissues. Thus, BSe-B demonstrates robust TP-PDT capabilities, making it a promising dual-purpose tool for cancer diagnosis and treatment.

Effect of gum Arabic on antifungal photodynamic activity of curcumin against Botrytis cinerea spores

This study investigated the effect of gum Arabic on curcumin's phototoxicity against Botrytis cinerea, a significant cause of postharvest losses in horticultural produce. Curcumin-loaded nanoparticle suspensions and emulsions stabilized with gum Arabic were prepared and their absorbance, fluorescence emission, physicochemical properties, antimicrobial photodynamic activity (using response surface methodology (RSM)), and reactive oxygen species (ROS) generation (via electron paramagnetic resonance (EPR) spectroscopy) were evaluated. Fluorescence emission exhibited a blue shift (510-550 nm) in both formulations, with emulsions showing higher intensities due to a more hydrophobic environment. Gum Arabic concentration significantly influenced the physicochemical properties of both suspensions, with nanoparticle size decreasing from 572.80 nm to 202.80 nm as gum Arabic concentration increased from 0.5 % to 2.5 % (at 65 μM curcumin). Nanoparticle suspensions demonstrated higher antimicrobial efficacy, reducing B. cinerea spores by 0.39-3.40 log10(CFU.ml-1), compared to 0.00-0.46 log10(CFU.ml-1) in emulsions. The phototoxic effect was dependent on curcumin concentration and light irradiance, as demonstrated by RSM. EPR confirmed the generation of superoxide anion and hydroxyl radicals in both formulations, which indicated a Type I photodynamic mechanism, with nanoparticle suspensions having a sustained ROS generation. Overall, gum Arabic did not impair curcumin's antifungal photodynamic activity, making it as a promising stabiliser for curcumin-based treatments.

Enhanced Singlet Oxygen Generation in Aggregates of Naphthalene-Fused BODIPY and Its Application in Photodynamic Therapy

Several reports are available on aggregation-induced emission and its applications in biomedical imaging and other material sciences. However, enhancement of singlet oxygen generation in nanoaggregates is rarely reported. Here, we report the synthesis of Naph-BODIPY Br2, which absorbs at 661 nm (monomer) with a high molar absorption coefficient. The presence of bromine promotes intersystem crossing, thereby enhancing the singlet oxygen quantum yield (ΦΔ ∼ 0.50 in methanol). In order to increase hydrophilicity, we developed Naph-BODIPY Br2 nanoaggregates (∼100 nm), which demonstrated aggregation-induced properties and exhibited a bathochromic shift with an absorption maximum at 757 nm. The bathochromic shift in the UV-vis spectra due to aggregation is corroborated by TD-DFT analysis. The computational data also confirm the presence of a low-lying triplet state, which enhances the generation of singlet oxygen, making it effective for photodynamic therapy. These aggregates showed excellent singlet oxygen generation in aqueous media, compared to their monomeric form and standard methylene blue. Their hydrophilic nature and high singlet oxygen generation enabled significant phototoxicity against human carcinoma cells with IC50 values of 4.06 ± 0.01 and 4.09 ± 0.1 μM, respectively, for MCF-7 and A549 cells upon 5 min exposure to light. Moreover, their phototoxicity further increases with an increasing exposure time of light for both cell lines. Notably, Naph-BODIPY Br2 nanoaggregates exhibited nearly zero dark cell toxicity and effectively induced apoptosis in cancer cells upon light activation, highlighting their potential as powerful photosensitizers for photodynamic cancer therapy.

Investigation of excited states of BODIPY derivatives and non-orthogonal dimers from the perspective of singlet fission

We report state of the art electronic structure calculations RICC2 and XMCQDPT of BODIPY nonorthogonal dimers to understand the photophysical processes from the intramolecular singlet fission (iSF) perspective. We have calculated singlet, triplet and quintet states at the XMCQDPT(8,8)/cc-pVDZ level of theory and diabatic singlet states at the XMCQDPT(4,4)/cc-pVDZ level of theory. In all the systems studied, charge transfer states (1(CA) and 1(AC)) couple strongly with locally excited (1(S1S0)) and multiexcitonic (1(T1T1)) states. The rates of formation of the multiexcitonic state from the locally excited state are very low on account of large activation energy (E(1(T1T1)) - E(1(S1S0))). A relaxed scan along the torsional angle revealed contrasting results for axial and orthogonal conformers. We proposed a probable mechanism for contrasting photophysical properties of dimers B[3,3] and B[2,8]. We also found that substitution of CN, NH2 and BH2 at meso, β and α positions reduces the energy gap (ΔSF = 2E(T1) - E(S1)) significantly, making iSF a competing process in triplet state generation. Intrigued by the success of the CN group at the meso position in reducing the energy gap, we also studied the azaBODIPY monomer and its derivatives using the same methodology. The iSF is slightly endoergic with ΔSF ∼ 0.2 eV in these systems and iSF may play an important role in their photophysical responses.

Engineering Stimuli-Responsive Materials for Precision Medicine

Over the past decade, precision medicine has garnered increasing attention, making significant strides in discovering new therapeutic drugs and mechanisms, resulting in notable achievements in symptom alleviation, pain reduction, and extended survival rates. However, the limited target specificity of primary drugs and inter-individual differences have often necessitated high-dosage strategies, leading to challenges such as restricted deep tissue penetration rates and systemic side effects. Material science advancements present a promising avenue for these issues. By leveraging the distinct internal features of diseased regions and the application of specific external stimuli, responsive materials can be tailored to achieve targeted delivery, controllable release, and specific biochemical reactions. This review aims to highlight the latest advancements in stimuli-responsive materials and their potential in precision medicine. Initially, we introduce disease-related internal stimuli and capable external stimuli, elucidating the reaction principles of responsive functional groups. Subsequently, we provide a detailed analysis of representative pre-clinical achievements of stimuli responsive materials across various clinical applications, including enhancements in the treatment of cancers, injury diseases, inflammatory diseases, infection diseases, and high-throughput microfluidic biosensors. Finally, we discuss some clinical challenges, such as off-target effects, long-term impacts of nano-materials, potential ethical concerns, and offer insights into future perspectives of stimuli-responsive materials.

Bacterial Photodynamic Inactivation: Eradication of Staphylococcus aureus and Escherichia coli Mediated by Pyridinium-Pyrazolyl Zinc(II) Phthalocyanines

Antimicrobial resistance remains an enduring global health issue, manifested when microorganisms, such as bacteria, lack responsiveness to antimicrobial treatments. Photodynamic inactivation (PDI) of microorganisms arises as a noninvasive, nontoxic, and repeatable alternative for the inactivation of a broad range of pathogens. So, this study reports the synthesis, structural characterization, and photophysical properties of a new tetra-β-substituted pyridinium-pyrazolyl zinc(II) phthalocyanine (ZnPc 1a) that was compared with two previously described pyridinium-pyrazolyl ZnPcs 2a and 3a. The PDI efficacy of these three ZnPcs (1a-3a) against a drug-resistant Gram-positive bacterium (as Staphylococcus aureus) and a Gram-negative bacterium (as Escherichia coli) is also reported. The PDI efficacy toward these bacteria was examined with ZnPcs 1a-3a in the 5.0-10.0 μM range using a white light source with an irradiance of 150 mW/cm2. All ZnPcs displayed a significant PDI activity against S. aureus, with reductions superior to 3 Log CFU/mL. Increasing the treatment time, the E. coli was inactivated until the detection limit of the method (>6.3 Log CFU/mL) using the quaternized ZnPcs 1a-3a (10.0 μM, 120 min) being the inactivation time was reduced when added the KI for ZnPcs 1a and 3a. These findings demonstrate the effective PDI performance of pyridinium-pyrazolyl group-bearing PSs, indicating their potential use as a versatile antimicrobial agent for managing infections induced by Gram-negative and Gram-positive bacteria.

Unveiling the potent antimicrobial photodynamic therapy in Gram-positive and Gram-negative bacteria - Water remediation with monocharged chlorins

Water pollution is a significant concern worldwide, and it includes contaminants such as antibiotic-resistant pathogens. Antimicrobial photodynamic therapy (aPDT) offers a non-invasive and non-toxic alternative for the inactivation of these microorganisms. So, this study reports the synthesis, structural characterisation, photophysical properties, and aPDT efficacy of cationic free-base and zinc(II) chlorin (Chl) derivatives bearing N,N-dimethylpyrrolydinium groups (H2Chl 1a and ZnChl 1b). The aPDT assays were performed against two bacterial models: Staphylococcus aureus (Gram-(+)) and Escherichia coli (Gram-(-)). The H2Chl 1a and ZnChl 1b distinct's solubility profile, coupled with their ability to generate singlet oxygen (1O2) under light exposure, (H2Chl 1a, ФΔ = 0.58 < TPP, ФΔ = 0.65 < ZnChl 1b, ФΔ = 0.83) opens up their potential application as photosensitizers (PS) in aPDT. The effectiveness of H2Chl 1a and ZnChl 1b at 1.0 and 5.0 μM in aPDT against S. aureus and E. coli at 500 W m-2 (total exposure time: 60-120 min) showed a viability reduction >6.0 log10 CFU mL-1. Additionally, KI was used as a coadjuvant to potentiate the photoinactivation of E. coli, reaching the method's detection limit (>4.0 log10 RLU). As most of the PS developed to inactivate Gram-negative bacteria are cationic with three or more charges, the fact that the H2Chl 1a and ZnChl 1b with only one cationic charge photoinactivate E. coli at low concentrations and with a reduced light dose, it is an importing discovery that deserves further exploration. These monocharged chlorin dyes have the potential for water remediation.

A molecular dynamics simulation study of EthylChlorophyllide A molecules confined in a SiO2 nanoslit

This paper investigates the dynamic behavior of EthylChlorophyllide A (EChlideA) molecules in a methanol solution confined within a 4 nm silica nanoslit, using molecular dynamics simulations over a duration of 1 ms. Three systems, containing 1, 2, and 4 solutes, were studied at 298 K. The results demonstrate that EChlideA molecules predominantly adsorb onto the silica surfaces, driven by specific interactions between chlorin ring's methyl group and the hydroxyl groups of the silica. This adsorption leads to stable binding, particularly in less crowded environments, as indicated by the potential of mean force analysis. Higher molecular concentrations, such as those with four EChlideA molecules, introduce variation in binding strength due to molecular aggregation and complex interactions. The orientation analysis reveals that the chlorin ring tends to align parallel to the surface, requiring rotational adjustments during surface diffusion. In addition, solvent coordination around the Mg ion remains consistent under bulk conditions, although with some variation in higher concentrations. This study also highlights a decrease in linear diffusion and an increase in rotational relaxation times for EChlideA molecules within the confined nanoslit, reflecting the influence of molecular concentration and arrangement on their dynamics. These findings provide valuable insights into the role of surface interactions, molecular orientation, and solvent coordination in confined environments, offering implications for the design of nanoscale systems.

Supramolecular Porphyrin Photosensitizers Based on Host-Guest Recognition for In Situ Bacteria-Responsive Near-Infrared Photothermal Therapy

Antibiotic resistance resulting from the overuse of antibiotics sets a high challenge for brutal antimicrobial treatment. Although photothermal therapy (PTT) overcomes the awkward situation of antibiotic resistance, it usually mistakenly kills the beneficial bacteria strains when eliminating pernicious bacteria. Specifically recognizing and damaging the target pathogens is urgently required for PTT-mediated sterilization strategy. Based on the host-guest recognition between cucurbit[10]uril (CB[10]) and porphyrins, two water-soluble supramolecular porphyrins are designed and implement selective bactericidal effect via in situ bacteria-responsive near-infrared (NIR) PTT. With the help of CB[10], the π-π stacking and hydrophobic interactions of porphyrins are efficiently inhibited, thus contributing to a good photostability and a high photothermal conversion efficiency. Attributing to the matching reduction potential between facultative anaerobic Escherichia coli (E. coli) and porphyrins, they are selectively in situ reduced into supramolecular phlorin and supramolecular chlorin by E. coli, successfully achieving a selective sterilization against E. coli. In vivo, the in situ bacteria-responsive NIR PTT systems also promote the quick recovery of E. coli-infected abscesses and trauma on mice without inducing obvious systemic toxicity, providing a new alternative to the current antibiotics and helping relieve the global public health crisis of abusive antibiotics.

A Spectroscopic Study on the Amyloid-β Interaction with Clicked Peptide-Porphyrin Conjugates: a Vision Toward the Detection of Aβ Peptides in Aqueous Solution

Alzheimer's disease (AD) is a multifactorial form of dementia mainly affecting people in the elderly, but no effective cure is available. According to the amyloid hypothesis the aggregation of Amyloid-β (Aβ) into oligomeric toxic species is believed to concur with the onset and progression of the disease heavily. By using a click chemistry approach, we conjugated a suitable designed peptide sequence to a metalloporphyrin moiety to obtain three hybrid peptide systems to be studied for their interaction with Amyloid-β peptides. The aim is to get new tools for the diagnosis and therapy in AD. The results described in this study, which were obtained through spectroscopic techniques (UV-Vis, CD, bis-Ans and intrinsic porphyrin Fluorescence), Microfluidics (GCI) and cell biology (MTT, Live cell imaging and flow cytometry), reveal interesting features about the structure-activity relationships connecting these conjugates with the interaction with Aβ, as well as on their potential use as sensing systems. In our opinion the data reported in this paper make the porphyrin-peptide conjugates highly compelling for further exploration as spectroscopic probes to detect Aβ biomarkers in biological fluids.

A phase I clinical trial of sonodynamic therapy combined with radiotherapy for brainstem gliomas

Brainstem gliomas (BSGs) are a class of clinically refractory malignant tumors for which there is no uniform and effective treatment protocol. Ultrasound and radiation can activate hematoporphyrin and produce sonodynamic and radiodynamic effects to kill cancer cells. Therefore, we conducted the first phase I clinical trial of sonodynamic therapy (SDT) combined with radiotherapy (RT) for the treatment of BSGs to verify its safety and efficacy. We conducted a study of SDT combined with RT in 11 patients with BSGs who received SDT and RT after hematoporphyrin administration. Magnetic resonance imaging was performed during this period to assess the tumor, and adverse events were recorded. All adverse events recorded were grade 1-2; no grade 3 or more serious adverse events were observed. Treatment was well tolerated, and no dose-limiting toxicities were observed. There were no treatment-related deaths during the course of treatment. 8 of 11 patients (72.7%) maintained stable disease, 2 (18.2%) achieved partial response, and the tumors were still shrinking as of the last follow-up date. The median progression-free survival (PFS) for patients was 9.2 (95% confidence interval [CI] 6.2-12.2) months, and the median overall survival (OS) was 11.7 (95% CI 9.6-13.8) months. Therefore, SDT combined with RT has a favorable safety and feasibility and shows a preliminary high therapeutic potential.

Assessing the efficacy of carbon nanodots derived from curcumin on infectious diseases

INTRODUCTION

The threat of new, emerging, and multidrug-resistant microbes is increasing which has created the necessity for new antimicrobials. In this regard, nanotechnology can be an alternative for the treatment of infectious microbes. Curcumin has been used since ancient times as antimicrobials; however, it has limitations due to its less aqueous solubility, bioavailability, and biocompatibility. This problem can be solved by curcumin-derived carbon nanodots, which are emerging antimicrobials of <10 nm size, water-soluble, biocompatible, less toxic, and fluorescent.

AREAS COVERED

The review discusses the application of curcumin-derived carbon nanodots against various pathogenic microbes including bacteria and dreaded viruses like SARS-CoV-2. In addition, the role of curcumin carbon nanodots in biolabelling of pathogenic microbes, mechanism of action, bioimaging, and therapy has been critically examined.

EXPERT OPINION

Carbon nanodots play an important role in combating pathogenic microbes by early diagnosis, bioimaging, nanocarrier for antimicrobial drugs, and therapy of infectious diseases. Curcumin carbon nanodots have already demonstrated their benefits of being water soluble, bioavailable, and biocompatible. However, more thorough research is needed to understand the efficacy and safety of curcumin carbon nanodots. In the future, curcumin-derived carbon nanodots can be used as alternative antimicrobial agents to fight microbial infections including multidrug-resistant microbes.

New strategies to enhance antimicrobial photo-sonodynamic therapy based on nanosensitizers against bacterial infections

The rapid evolution and spread of multidrug resistance among bacterial pathogens has significantly outpaced the development of new antibiotics, underscoring the urgent need for alternative therapies. Antimicrobial photodynamic therapy and antimicrobial sonodynamic therapy have emerged as promising treatments. Antimicrobial photodynamic therapy relies on the interaction between light and a photosensitizer to produce reactive oxygen species, which are highly cytotoxic to microorganisms, leading to their destruction without fostering resistance. Antimicrobial sonodynamic therapy, a novel variation, substitutes ultrasound for light to activate the sonosensitizers, expanding the therapeutic reach. To increase the efficiency of antimicrobial photodynamic therapy and antimicrobial sonodynamic therapy, the combination of these two methods, known as antimicrobial photo-sonodynamic therapy, is currently being explored and considered a promising approach. Recent advances, particularly in the application of nanomaterials, have further enhanced the efficacy of these therapies. Nanosensitizers, due to their improved reactive oxygen species generation and targeted delivery, offer significant advantages in overcoming the limitations of conventional sensitizers. These breakthroughs provide new avenues for treating bacterial infections, especially multidrug-resistant strains and biofilm-associated infections. Continued research, including comprehensive clinical studies, is crucial to optimizing nanomaterial-based antimicrobial photo-sonodynamic therapy for clinical use, ensuring their effectiveness in real-world applications.

Effects of Zinc Phthalocyanine Photodynamic Therapy on Vital Structures and Processes in Hela Cells

This work presents results on the efficiency of newly designed zinc phthalocyanine-mediated photodynamic therapy of both tumoral and nontumoral cell models using the MTT assay. Further detailed examinations of mechanistic and cell biological effects were focused on the HELA cervical cancer cell model. Here, ROS production, changes in the mitochondrial membrane potential, the determination of genotoxicity, and protein changes determined by capillary chromatography and tandem mass spectrometry with ESI were analyzed. The results showed that, in vitro, 5 Jcm-2 ZnPc PDT caused a significant increase in reactive oxygen species. Still, except for superoxide dismutase, the levels of proteins involved in cell response to oxidative stress did not increase significantly. Furthermore, this therapy damaged mitochondrial membranes, which was proven by a more than 70% voltage-dependent channel protein 1 level decrease and by a 65% mitochondrial membrane potential change 24 h post-therapy. DNA impairment was assessed by an increased level of DNA fragmentation, which might be related to the decreased level of DDB1 (decrease in levels of more than 20% 24 h post-therapy), a protein responsible for maintaining genomic integrity and triggering the DNA repair pathways. Considering these results and the low effective concentration (LC50 = 30 nM), the therapy used is a potentially very promising antitumoral treatment.

Use of photodynamic therapy to combat recurrent pharyngotonsillitis: Three case reports

BACKGROUND

Pharyngotonsillitis (PT) is an inflammatory and infectious condition affecting the tonsils in the oropharynx, predominantly caused by a variety of viral, fungal, and bacterial pathogens, including Streptococcus pyogenes. With the increasing challenge of antibiotic resistance, alternative therapeutic approaches are needed.

METHODS

This study explores the effectiveness and safety of Photodynamic Therapy (PDT) as a therapeutic approach for managing acute PT. PDT involves the use of a photosensitizer, light, and molecular oxygen. We utilized a curcumin-based photosensitizer incorporated into a gum formulation, followed by exposure to blue LED irradiation (455 ± 30 nm, intensity of 200 mW for 6 min) with 1 to 2 PDT sessions depending on the clinical case.

RESULTS

The treatment's impact was assessed through systematic monitoring of clinical progression post-treatment, encompassing clinical history, examination, and follow-up. In all three cases examined, PDT was observed to effectively eradicate the infection and prevent its recurrence during the period evaluated.

CONCLUSION

Photodynamic Therapy, using a curcumin-based photosensitizer and blue LED light, appears to be a promising alternative to traditional antibiotics for the treatment of PT, demonstrating both efficacy in infection eradication and safety in application. Further studies are recommended to substantiate these findings and explore long-term outcomes.

Green Synthesis of Au-Doped Tin Oxide Nanoparticles Using Teucrium Polium Extract with Potential Applications in Photodynamic Therapy

Objective: The green synthesis of Tin(IV) oxide (SnO2): Gold (Au) nanoparticles (NPs) using Teucrium polium medicinal plant extract was investigated, and the NPs were characterized and tested as photosensitizers to produce reactive oxygen species (ROS). Methods: The cytotoxic effect on C26 cells was investigated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) technique. The results showed their toxicity in a dose-dependent manner. The green synthesis of SnO2:Au NPs was achieved for the first time using an extract of T. polium medicinal plant as a reducing and stabilizing agent. The produced NPs were examined for their application in photodynamic therapy (PDT) for cancer. Results: Methylene blue and anthracene were used to confirm that the photosensitizer could produce ROS when excited with UVA radiation. The anticancer activity of SnO2:Au was investigated in vitro using the C26 cell line and an MTT assay, showing that PDT with SnO2:Au NPs could inhibit cancer cell proliferation. Conclusions: The significant afterglow of the SnO2:Au NPs could cause the generation of ROS to continue several minutes after switching off the light source.

Studies related to the enhanced the effect of 5-aminolevulinic acid-based photodynamic therapy combined with tirapazamine

OBJECTIVE

5-aminolevulinic acid (5-ALA) is a precursor of the photosensitizer Protoporphyrin IX (PpIX) and photodynamic therapy (PDT) with 5-ALA has been used in clinical practice. However, tumor cellular hypoxia severely affects the efficiency of photodynamic therapy. In this study, photodynamic therapy was combined with tirapazamine to investigate the effects of the combined intervention and the related mechanisms it may involve.

METHODS

Colony formation assays were used to demonstrate cell proliferation. Transwell assays were performed to observe the effect on cell invasion and metastasis after the corresponding intervention. DCFH-DA probe was used to detect the reactive oxygen species content. Flow cytometry was used to detect the effects of the interventions on apoptosis and cell cycle. The relevant pathways that may be involved are explored by examining the expression levels of the relevant proteins and genes.

RESULTS

Colony formation assays indicated that the combined intervention inhibited cell proliferation. Transwell assays demonstrated that PDT combined with TPZ effectively inhibited tumor cell invasion and metastasis. In addition, fluorescence intensity generated by DCFH-DA oxidation was detected indicating that the combined intervention increased the formation of reactive oxygen species. Flow cytometry clearly showed that the combination of PDT and TPZ further increased apoptosis and cell cycle arrest. The results of western blotting and qRT-PCR experiments confirmed that the combination therapy inhibited HIF-1α/VEGF axis and the PI3K/Akt/mTOR pathway activation.

CONCLUSION

5-ALA-PDT combined with TPZ can inhibit cell proliferation, increase apoptosis, and inhibit the PI3K/Akt/mTOR pathway, thus inhibiting tumor growth and metastasis and improving anti-cancer effects.

Encapsulation of photosensitizer worsen cell responses after photodynamic therapy protocol and polymer micelles act as biomodulators on their own

Photodynamic therapy (PDT) is a photochemical therapeutic modality used clinically for dermatological, ophthalmological and oncological applications. Pheo a was used as a model photosensitizer, either in its free form or encapsulated within poly(ethylene oxide)-block-poly(ε-caprolactone) (PEO-PCL) polymer micelles. Block copolymer micelles are water-soluble biocompatible nanocontainers with great potential for delivering hydrophobic drugs. Empty PEO-PCL micelles were also tested throughout the experiments. The goal was to conduct an in vitro investigation into human colorectal tumor HCT-116 cellular responses induced by free and encapsulated Pheo a in terms of cell architecture, plasma membrane exchanges, mitochondrial function, and metabolic disturbances. In a calibrated PDT protocol, encapsulation enhanced Pheo a penetration (flow cytometry, confocal microscopy) and cell death (Prestoblue assay), causing massive changes to cell morphology (SEM) and cytoskeleton organization (confocal), mitochondrial dysfunction and loss of integrity (TEM), rapid and massive ion fluxes across the plasma membrane (ICP-OES, ion chromatography), and metabolic alterations, including increased levels of amino acids and choline derivatives (1H NMR). The detailed investigation provides insights into the multifaceted effects of encapsulated Pheo-PDT, emphasizing the importance of considering both the photosensitizer and its delivery system in understanding therapeutic outcomes. The study also raises questions as to the broader impact of empty nanovectors per se, and encourages a more comprehensive exploration of their biological effects.

From (Sub)Porphyrins to (Sub)Phthalocyanines: Aromaticity Signatures in the UV-Vis Absorption Spectra

The development of novel synthetic methods has greatly expanded the toolbox available to chemists for engineering porphyrin and phthalocyanine derivatives with precise electronic and optical properties. In this study, we focus on the UV-vis absorption characteristics of substituted phthalocyanines and their contracted analogs, subphthalocyanines, which feature nonplanar, bowl-shaped geometries. These macrocycles, which are central to numerous applications in materials science and catalysis, possess extensive π-conjugated systems that drive their unique electronic properties. We explore how the change from a metalloid (B) to a metal (Zn) and the resulting coordination environments influence the aromaticity and, consequently, the spectroscopic features of these systems. A combined computational and experimental approach reveals a direct correlation between the aromaticity of the external conjugated pathways and the Q bands in the UV-vis spectra. Our findings highlight key structural modifications that can be leveraged to fine-tune the optical properties of porphyrinoid systems, offering new pathways for the design of advanced materials and catalysts with tailored functionalities.

Exploring the therapeutic potential of lipid-based nanoparticles in the management of oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is a highly malignant and invasive tumor with significant mortality and morbidity. Current treatment modalities such as surgery, radiotherapy, and chemotherapy encounter significant limitations, such as poor targeting, systemic toxicity, and drug resistance. There is an urgent need for novel therapeutic strategies that offer targeted delivery, enhanced efficacy, and reduced side effects. The advent of lipid-based nanoparticles (LNPs) offers a promising tool for OSCC therapy, potentially overcoming the limitations of current therapeutic approaches. LNPs are composed of biodegradable and biocompatible lipids, which minimize the risk of toxicity and adverse effects. LNPs can encapsulate hydrophobic drugs, improving their solubility and stability in the biological environment, thereby enhancing their bioavailability. LNPs demonstrate significantly higher ability to encapsulate lipophilic drugs than other nanoparticle types. LNPs offer excellent storage stability, minimal drug leakage, and controlled drug release, making them highly effective nanoplatforms for the delivery of chemotherapeutic agents. Additionally, LNPs can be modified by complexing them with specific target ligands on their surface. This surface modification allows the active targeting of LNPs to the tumors in addition to the passive targeting mechanism. Furthermore, the PEGylation of LNPs improves their hydrophilicity and enhances their biological half-life by reducing clearance by the reticuloendothelial system. This review aims to discuss current treatment approaches and their limitations, as well as recent advancements in LNPs for better management of OSCC.

Fullerene Derivatives for Tumor Treatment: Mechanisms and Application

Fullerenes hold tremendous potential as alternatives to conventional chemotherapy or radiotherapy for tumor treatment due to their abilities to photodynamically kill tumor cells, destroy the tumor vasculature, inhibit tumor metastasis and activate anti-tumor immune responses, while protecting normal tissue through antioxidative effects. The symmetrical hollow molecular structures of fullerenes with abundant C=C bonds allow versatile chemical modification with diverse functional groups, metal clusters and biomacromolecules to synthesize a wide range of fullerene derivatives with increased water solubility, improved biocompatibility, enhanced photodynamic properties and stronger targeting abilities. This review introduces the anti-tumor mechanisms of fullerenes and summarizes the most recent works on the functionalization of fullerenes and the application of fullerene derivatives in tumor treatment. This review aims to serve as a valuable reference for further development and clinical application of anti-tumor fullerene derivatives.

Sonodynamic Therapy for HER2+ Breast Cancer with Iodinated Heptamethine Cyanine-Trastuzumab Conjugate

The first example of sonodynamic therapy (SDT) with a cyanine dye-antibody conjugate is reported. The aim of this study was to evaluate the sonodynamic efficacy of a trastuzumab-guided diiodinated heptamethine cyanine-based sensitizer, 2ICy7-Ab, versus its non-iodinated counterpart, Cy7-Ab, in a human epidermal growth factor receptor 2-positive (HER2+) xenograft model. In addition, the combined sonodynamic and photodynamic (PDT) effects were investigated. A single intravenous injection of 2ICy7-Ab followed by sonication or combined sonication and photoirradiation in mice resulted in complete tumor growth suppression compared with the nontreated control and showed no detectable toxicity to off-target tissues. In contrast, Cy7-Ab provided only a moderate therapeutic effect (~1.4-1.6-fold suppression). SDT with 2ICy7-Ab resulted in a 3.5-fold reduction in tumor volume within 45 days and exhibited 13-fold greater tumor suppression than PDT alone. In addition, 2ICy7-Ab showed more durable sonostability than photostability. The sonotoxicity of the iodinated versus noniodinated counterparts is attributed to the increased generation of hydroxyl radicals, superoxide, and singlet oxygen. We observed no significant contribution of PDT to the efficacy of the combined SDT and PDT, indicating that SDT with 2ICy7-Ab is superior to PDT alone. These new findings set the stage for the application of cyanine-antibody conjugates for fluorescently monitored targeted sonodynamic treatment of cancer.

Modulation of Photosensitizing Responses in Cell Culture Environments by Different Medium Components

Many cell culture experiments are performed under light to evaluate the photodynamic or photosensitizing efficacy of various agents. In this study, the modulation of photosensitizing responses and phototoxicity under cell culture conditions by different medium components was investigated. The significant levels of reactive oxygen species (ROS) generated from DMEM, RPMI 1640, and MEM were observed under the irradiation of fluorescent light (FL) and white and blue LEDs, indicating that these media have their own photosensitizing properties; DMEM showed the most potent property. Phenol red-free DMEM (Pf-D) exhibited a stronger photosensitizing property than normal DMEM by 1.31 and 1.25 times under FL and blue LEDs, respectively; phenol red and riboflavin-free DMEM (PRbf-D) did not show any photosensitizing properties. The inhibitory effect on light transmission was more pronounced in DMEM than in RPMI, and the interference effect on green LED light was greatest at 57.8 and 27.4%, respectively; the effect disappeared in Pf-D. The media containing riboflavin induced strong phototoxicity in HaCaT keratinocytes by generating H2O2 under light irradiation, which was quenched by sodium pyruvate in the media. The presence of serum in the media was also reduced the phototoxicity; H2O2 levels in the media decreased serum content dependently. The phototoxicity of erythrosine B and protoporphyrin IX under FL was more sensitively pronounced in PRbf-D than in DMEM. The present results indicate that several medium components, including riboflavin, phenol red, sodium pyruvate, and serum, could modulate photosensitizing responses in a cell culture system by inducing photosensitizing activation and by interfering with irradiation efficacy and ROS generation.

Photosensitized Oxidation of Free and Peptide Tryptophan to N-Formylkynurenine

The oxidation of proteins and, in particular, of tryptophan (Trp) residues leads to chemical modifications that can affect the structure and function. The oxidative damage to proteins in photochemical processes is relevant in the skin and eyes and is related to a series of pathologies triggered by exposure to electromagnetic radiation. In this work, we studied the photosensitized formation of N-formylkynurenine (NFKyn) from Trp in different reaction systems. We used two substrates: free Trp and a peptide of nine amino acid residues, with Trp being the only oxidizable residue. Two different photosensitizers were employed: Rose Bengal (RB) and pterin (Ptr). The former is a typical type II photosensitizer [acts by producing singlet oxygen (1O2)]. Ptr is the parent compound of oxidized or aromatic pterins, natural photosensitizers that accumulate in human skin under certain pathological conditions and act mainly through type I mechanisms (generation of radicals). Experimental data were collected in steady photolysis, and the irradiated solutions were analyzed by chromatography (HPLC). Results indicate that the reaction of Trp with 1O2 initiates the process leading to NFKyn, but different competitive pathways take place depending on the photosensitizer and the substrate. In Ptr-photosensitization, a type I mechanism is involved in secondary reactions accelerating the formation of NFKyn when free Trp is the substrate.

Targeted mitochondrial nanomaterials in biomedicine: Advances in therapeutic strategies and imaging modalities

Mitochondria, pivotal organelles crucial for energy generation, apoptosis regulation, and cellular metabolism, have spurred remarkable advancements in targeted material development. This review surveys recent breakthroughs in targeted mitochondrial nanomaterials, illuminating their potential in drug delivery, disease management, and biomedical imaging. This review approaches from various application perspectives, introducing the specific applications of mitochondria-targeted materials in cancer treatment, probes and imaging, and diseases treated with mitochondria as a therapeutic target. Addressing extant challenges and elucidating potential therapeutic mechanisms, it also outlines future development trajectories and obstacles. By comprehensively exploring the diverse applications of targeted mitochondrial nanomaterials, this review aims to catalyze innovative treatment modalities and diagnostic approaches in medical research. STATEMENT OF SIGNIFICANCE: This review presents the latest advancements in mitochondria-targeted nanomaterials for biomedical applications, covering diverse fields such as cancer therapy, bioprobes, imaging, and the treatment of various systemic diseases. The novelty and significance of this work lie in its systematic analysis of the intricate relationship between mitochondria and different diseases, as well as the ingenious design strategies employed to harness the therapeutic potential of nanomaterials. By providing crucial insights into the development of mitochondria-targeted nanomaterials and their applications, this review offers a valuable resource for researchers working on innovative treatment modalities and diagnostic approaches. The scientific impact and interest to the readership lie in the identification of promising avenues for future research and the potential for clinical translation of these cutting-edge technologies.

Computational Exploration of the Mechanism of Action of a Sorafenib-Containing Ruthenium Complex as an Anticancer Agent for Photoactivated Chemotherapy

Ruthenium(II) polypyridyl complexes are being tested as potential anticancer agents in different therapies, which include conventional chemotherapy and light-activated approaches. A mechanistic study on a recently synthesized dual-action Ru(II) complex [Ru(bpy)2(sora)Cl]+ is described here. It is characterized by two mono-dentate leaving ligands, namely, chloride and sorafenib ligands, which make it possible to form a di-aquo complex able to bind DNA. At the same time, while the released sorafenib can induce ferroptosis, the complex is also able to act as a photosensitizer according to type II photodynamic therapy processes, thus generating one of the most harmful cytotoxic species, 1O2. In order to clarify the mechanism of action of the drug, computational strategies based on density functional theory are exploited. The photophysical properties of the complex, which include the absorption spectrum, the kinetics of ISC, and the character of all the excited states potentially involved in 1O2 generation, as well as the pathway providing the di-aquo complex, are fully explored. Interestingly, the outcomes show that light is needed to form the mono-aquo complex, after releasing both chloride and sorafenib ligands, while the second solvent molecule enters the coordination sphere of the metal once the system has come back to the ground-state potential energy surface. In order to simulate the interaction with canonical DNA, the di-aquo complex interaction with a guanine nucleobase as a model has also been studied. The whole study aims to elucidate the intricate details of the photodissociation process, which could help with designing tailored metal complexes as potential anticancer agents.

Singlet Oxygen Photophysics: From Liquid Solvents to Mammalian Cells

Molecular oxygen, O2, has long provided a cornerstone for studies in chemistry, physics, and biology. Although the triplet ground state, O2(X3Σg-), has garnered much attention, the lowest excited electronic state, O2(a1Δg), commonly called singlet oxygen, has attracted appreciable interest, principally because of its unique chemical reactivity in systems ranging from the Earth's atmosphere to biological cells. Because O2(a1Δg) can be produced and deactivated in processes that involve light, the photophysics of O2(a1Δg) are equally important. Moreover, pathways for O2(a1Δg) deactivation that regenerate O2(X3Σg-), which address fundamental principles unto themselves, kinetically compete with the chemical reactions of O2(a1Δg) and, thus, have practical significance. Due to technological advances (e.g., lasers, optical detectors, microscopes), data acquired in the past ∼20 years have increased our understanding of O2(a1Δg) photophysics appreciably and facilitated both spatial and temporal control over the behavior of O2(a1Δg). One goal of this Review is to summarize recent developments that have broad ramifications, focusing on systems in which oxygen forms a contact complex with an organic molecule M (e.g., a liquid solvent). An important concept is the role played by the M+•O2-• charge-transfer state in both the formation and deactivation of O2(a1Δg).

Expected role of photodynamic therapy to relieve skin damage in nuclear or radiological emergency: Review

Nuclear and radiological accidents can occur due to poor management, in transportation, radiation therapy and nuclear wards in hospitals, leading to extreme radiation exposure and serious consequences for human health. Additionally, in many of previous radiological accidents, skin damage was observed in patients and survivors due to the high radiation exposure. However, as part of a medical countermeasures in a nuclear/radiological emergency, it is critical to plan for the treatment of radiation-induced skin damage. Hence, the new, non-invasive technology of photodynamic therapy (PDT) is projected to be more effectively used for treating skin damage caused by high-dose radiation. PDT plays an important role in treating, repairing skin damage and promoting wound healing as evidenced by research. This review, highlighted and recommended potential impacts of PDT to repair and decrease radiation-induced skin tissue damage. Moreover, we have suggested some photosensitizer (PS) agent as radio-mitigator drugs to decrease radiobiological effects.

Lipid-Based Nanocarriers: Bridging Diagnosis and Cancer Therapy

Theranostics is a growing field that matches diagnostics and therapeutics. In this approach, drugs and techniques are uniquely coupled to diagnose and treat medical conditions synergically or sequentially. By integrating diagnostic and treatment functions in a single platform, the aim of theranostics is to improve precision medicine by tailoring treatments based on real-time information. In this context, lipid-based nanocarriers have attracted great scientific attention due to their biodegradability, biocompatibility, and targeting capabilities. The present review highlights the latest research advances in the field of lipid-based nanocarriers for cancer theranostics, exploring several ways of improving in vivo performance and addressing associated challenges. These nanocarriers have significant potential to create new perspectives in the field of nanomedicine and offer promise for a significant step towards more personalized and precise medicine, reducing side effects and improving clinical outcomes for patients. This review also presents the actual barriers to and the possible challenges in the use of nanoparticles in the theranostic field, such as regulatory hurdles, high costs, and technological integration. Addressing these issues through a multidisciplinary and collaborative approach among institutions could be essential for advancing lipid nanocarriers in the theranostic field. Such collaborations can leverage diverse expertise and resources, fostering innovation and overcoming the complex challenges associated with clinical translation. This approach will be crucial for realizing the full potential of lipid-based nanocarriers in precision medicine.

Pt(II) Bis(pyrrole-imine) complexes: Luminescent probes and cytotoxicity in MCF-7 cells†

Four Pt(II) bis(pyrrole-imine) Schiff base chelates (1-4) were synthesised by previously reported methods, through a condensation reaction, and the novel crystal structure of 2,2'-{propane-1,3-diylbis[nitrilo(E)methylylidene]}bis(pyrrol-1-ido)platinum(II) (1) was obtained. Pt(II) complexes 1-4 exhibited phosphorescence, with increased luminescence in anaerobic solvents or when bound to human serum albumin (HSA). One of the complexes shows a 15.6-fold increase in quantum yield when bound to HSA and could be used to detect HSA concentrations as low as 5 nM. Pt(II) complexes 1-3 was investigated as potential theranostic agents in MCF-7 breast cancer cells, but only complex 3 exhibited cytotoxicity when irradiated with UV light (λ355nmExcitation). Interestingly, the cytotoxicity of complex 1 was unresponsive to UV light irradiation. This indicates that only complex 3 can be considered a potential photosensitising agent.

Photodynamic therapy on mRNA levels in bacteria

Antimicrobial photodynamic therapy (aPDT) has shown efficacy in inactivating different bacterial species by photosensitizer-induced free radical production. Despite aPDT is considered unable to cause resistant strains, enzymatic pathways for detoxification of reactive oxygen species and transmembrane photosensitizer efflux systems could cause resistance to aPDT. Resistance mechanisms can be evaluated by measurement of mRNA from by quantitative reverse transcription polymerase chain reaction (RT-qPCR). Thus, the aim of this study was to access the mRNA level data obtained by RT-qPCR in bacterial cells submitted to photodynamic therapy. Studies performed on mRNA levels in bacteria after PDT were assessed on MEDLINE/Pubmed. The mRNA levels from genes related to various functions have been successfully evaluated in both Gram-positive and -negative bacteria after aPDT by RT-qPCR. Such an approach has improved the understanding of aPDT-induced effects, and reinforced the effectiveness of aPDT on bacteria, which can cause infections in different human tissues.

One-pot synthesis and covalent conjugation of methylene blue in mesoporous silica nanoparticles - A platform for enhanced photodynamic therapy

Photodynamic therapy (PDT) is an emerging clinical modality for diverse disease conditions, including cancer. This technique involves, the generation of cytotoxic reactive oxygen species by a photosensitizer in the presence of light and oxygen. Methylene blue (MB) is a cationic dye with an ability to act as photosensitizing and bioimaging agent. The direct utilization of MB as photosensitizer for biological applications has often been impeded by its poor photostability and unwanted tissue interactions. Nanocarriers such as mesoporous silica nanoparticles (MSNs) provide an effective means of overcoming these limitations. However, the mere physical adsorption of the dye within the MSN can result in leakage, compromising the effectiveness of PDT. Therefore, in this work, we report the conjugation of MB into MSNs using novel MB-silane derivatives, namely MBS1 and MBS2, to create dye-doped and amine-functionalized MSNs (MBS1-AMSN and MBS2-AMSN). The PDT efficacy and bioimaging capability of these nanoparticles were compared with those of MSNs in which MB was non-covalently encapsulated (MB@AMSN). The synthesized nanoparticles, ultra-small in size (≤ 35 ± 4 nm) with monodispersity, exhibited enhanced fluorescence quantum yields. MBS1-AMSN demonstrated 70-fold increase, while MBS2-AMSN showed 33-fold improvement in fluorescence quantum yields compared to MB@AMSN at the same concentration. Covalent conjugation resulted in a 2-fold enhancement in the singlet oxygen quantum yield of the dye in MBS1-AMSN and 1.2-fold improvement in MBS2-AMSN, compared to non-covalent encapsulation. Assessment on RAW 264.7 macrophages revealed superior fluorescence in cell imaging for MBS1-AMSN, establishing it as a more efficient PDT agent compared to MBS2-AMSN and MB@AMSN. These findings suggest that MBS1-AMSN holds significant potential as a theranostic nanoplatform for image-guided PDT.

Anti-Biofilm Effect of Hybrid Nanocomposite Functionalized with Erythrosine B on Staphylococcus aureus Due to Photodynamic Inactivation

Resistant biofilms formed by Staphylococcus aureus on medical devices pose a constant medical threat. A promising alternative to tackle this problem is photodynamic inactivation (PDI). This study focuses on a polyurethane (PU) material with an antimicrobial surface consisting of a composite based on silicate, polycation, and erythrosine B (EryB). The composite was characterized using X-ray diffraction and spectroscopy methods. Anti-biofilm effectiveness was determined after PDI by calculation of CFU mL-1. The liquid PU precursors penetrated a thin silicate film resulting in effective binding of the PU/silicate composite and the PU bulk phases. The incorporation of EryB into the composite matrix did not significantly alter the spectral properties or photoactivity of the dye. A green LED lamp and laser were used for PDI, while irradiation was performed for different periods. Preliminary experiments with EryB solutions on planktonic cells and biofilms optimized the conditions for PDI on the nanocomposite materials. Significant eradication of S. aureus biofilm on the composite surface was achieved by irradiation with an LED lamp and laser for 1.5 h and 10 min, respectively, resulting in a 10,000-fold reduction in biofilm growth. These results demonstrate potential for the development of antimicrobial polymer surfaces for modification of medical materials and devices.

Can Porphyrin-Triphenylphosphonium Conjugates Enhance the Photosensitizer Performance Toward Bacterial Strains?

Antimicrobial photodynamic treatment (aPDT) offers an alternative option for combating microbial pathogens, and in this way, addressing the challenges of growing antimicrobial resistance. In this promising and effective approach, cationic porphyrins and related macrocycles have emerged as leading photosensitizers (PS) for aPDT. In general, their preparation occurs via N-alkylation of nitrogen-based moieties with alkyl halides, which limits the ability to fine-tune the features of porphyrin-based PS. Herein, is reported that the conjugation of porphyrin macrocycles with triphenylphosphonium units created a series of effective cationic porphyrin-based PS for aPDT. The presence of positive charges at both the porphyrin macrocycle and triphenylphosphonium moieties significantly enhances the photodynamic activity of porphyrin-based PS against both Gram-positive and Gram-negative bacterial strains. Moreover, bacterial photoinactivation is achieved with a notable reduction in irradiation time, exceeding 50%, compared to 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrin (TMPyP), used as the reference and known as good PS. The improved capability of the porphyrin macrocycle to generate singlet oxygen combined with the enhanced membrane interaction promoted by the presence of triphenylphosphonium moieties represents a promising approach to developing porphyrin-based PS with enhanced photosensitizing activity.

Photodynamic Therapy: A Novel Approach for Head and Neck Cancer Treatment with Focusing on Oral Cavity

Oral cancers, specifically oral squamous cell carcinoma (OSCC), pose a significant global health challenge, with high incidence and mortality rates. Conventional treatments such as surgery, radiotherapy, and chemotherapy have limited effectiveness and can result in adverse reactions. However, as an alternative, photodynamic therapy (PDT) has emerged as a promising option for treating oral cancers. PDT involves using photosensitizing agents in conjunction with specific light to target and destroy cancer cells selectively. The photosensitizers accumulate in the cancer cells and generate reactive oxygen species (ROS) upon exposure to the activating light, leading to cellular damage and ultimately cell death. PDT offers several advantages, including its non-invasive nature, absence of known long-term side effects when administered correctly, and cost-effectiveness. It can be employed as a primary treatment for early-stage oral cancers or in combination with other therapies for more advanced cases. Nonetheless, it is important to note that PDT is most effective for superficial or localized cancers and may not be suitable for larger or deeply infiltrating tumors. Light sensitivity and temporary side effects may occur but can be managed with appropriate care. Ongoing research endeavors aim to expand the applications of PDT and develop novel photosensitizers to further enhance its efficacy in oral cancer treatment. This review aims to evaluate the effectiveness of PDT in treating oral cancers by analyzing a combination of preclinical and clinical studies.

Targeting tumor microenvironment with photodynamic nanomedicine

Photodynamic therapy (PDT) is approved for the treatment of certain cancers and precancer lesions. While early Photosensitizers (PS) have found their way to the clinic, research in the last two decades has led to the development of third-generation PS, including photodynamic nanomedicine for improved tumor delivery and minimal systemic or phototoxicity. In terms of nanoparticle design for PDT, we are witnessing a shift from passive to active delivery for improved outcomes with reduced PS dosage. Tumor microenvironment (TME) comprises of a complex and dynamic landscape with myriad potential targets for photodynamic nanocarriers that are surface-modified with ligands. Herein, we review ways to improvise PDT by actively targeting nanoparticles (NPs) to intracellular organelles such as mitochondria or lysosomes and so forth, overcoming the limitations caused by PDT-induced hypoxia, disrupting the blood vascular networks in tumor tissues-vascular targeted PDT (VTP) and targeting immune cells for photoimmunotherapy. We propose that a synergistic outlook will help to address challenges such as deep-seated tumors, metastasis, or relapse and would lead to robust PDT response in patients.

New Insights Concerning Phytophotodermatitis Induced by Phototoxic Plants

The present review explores the underlying mechanisms of phytophotodermatitis, a non-immunologic skin reaction triggered by certain plants followed by exposure to ultraviolet radiation emitted by sunlight. Recent research has advanced our understanding of the pathophysiology of phytophotodermatitis, highlighting the interaction between plant-derived photosensitizing compounds (e.g., furanocoumarins and psoralens) and ultraviolet light leading to skin damage (e.g., erythema, fluid blisters, edema, and hyperpigmentation), identifying these compounds as key contributors to the phototoxic reactions causing phytophotodermatitis. Progress in understanding the molecular pathways involved in the skin's response to these compounds has opened avenues for identifying potential therapeutic targets suitable for the management and prevention of this condition. The review emphasizes the importance of identifying the most common phototoxic plant families (e.g., Apiaceae, Rutaceae, and Moraceae) and plant species (e.g., Heracleum mantegazzianum, Ruta graveolens, Ficus carica, and Pastinaca sativa), as well as the specific phytochemical compounds responsible for inducing phytophototoxicity (e.g., limes containing furocoumarin have been linked to lime-induced photodermatitis), underscoring the significance of recognizing the dangerous plant sources. Moreover, the most used approaches and tests for accurate diagnosis such as patch testing, Wood's lamp examination, or skin biopsy are presented. Additionally, preventive measures such as adequate clothing (e.g., long-sleeved garments and gloves) and treatment strategies based on the current knowledge of phytophotodermatitis including topical and systemic therapies are discussed. Overall, the review consolidates recent findings in the field, covering a diverse array of phototoxic compounds in plants, the mechanisms by which they trigger skin reactions, and the implications for clinical management. By synthesizing these insights, we provide a comprehensive understanding of phytophotodermatitis, providing valuable information for both healthcare professionals and researchers working to address this condition.

A nitroreductase-responsive fluorescence turn-on photosensitizer for lysosomes imaging and photodynamic therapy

Nitroreductase (NTR) is a frequently used biomarker for the assessment of hypoxia level in tumors. As one of the main sources of enzymes, the dysfunction of lysosomes typically leads to various diseases. In this study, an NTR-triggered lysosome-targeting probe, M-TPE-P, was designed based on a tetraphenylethylene core. DFT calculation indicated that the probe possessed a narrow singlet-triplet energy gap (ΔEST), rendering it an efficient photosensitizer. The docking affinity of M-TPE-P to NTR revealed a strong structural match between them. Photophysical properties demonstrated that the probe exhibited high selectivity and sensitivity in a broad pH rang for detecting NTR with kcat/Km as 2.18 × 104 M-1 s-1. The detection limit was determined to be 53.6 ng/mL in 80 % PBS/DMSO solution. Cell imaging studies showed the probe could trace intracellular NTR behavior with green fluorescence. The colocalization analysis indicated its excellent lysosome-targeting specificity. In addition, the probe exhibited effective ROS generation ability and significant PDT effect after NIR irradiation, positioning it as a promising photosensitizer for cancer treatment.

Nrf2-Mediated Antioxidant Response and Drug Efflux Transporters Upregulation as Possible Mechanisms of Resistance in Photodynamic Therapy of Cancers

Photodynamic therapy (PDT) is a groundbreaking approach involving the induction of cytotoxic reactive oxygen species (ROS) within tumors through visible light activation of photosensitizers (PS) in the presence of molecular oxygen. This innovative therapy has demonstrated success in treating various cancers. While PDT proves highly effective in most solid tumors, there are indications that certain cancers exhibit resistance, and some initially responsive cancers may develop intrinsic or acquired resistance to PDT. The molecular mechanisms underlying this resistance are not fully understood. Recent evidence suggests that, akin to other traditional cancer treatments, the activation of survival pathways, such as the KEAP1/Nrf2 signaling pathway, is emerging as an important mechanism of post-PDT resistance in many cancers. This article explores the dual role of Nrf2, highlighting evidence linking aberrant Nrf2 expression to treatment resistance across a range of cancers. Additionally, it delves into the specific role of Nrf2 in the context of photodynamic therapy for cancers, emphasizing evidence that suggests Nrf2-mediated upregulation of antioxidant responses and induction of drug efflux transporters are potential mechanisms of resistance to PDT in diverse cancer types. Therefore, understanding the specific role(s) of Nrf2 in PDT resistance may pave the way for the development of more effective cancer treatments using PDT.