Photodynamic Therapy Review: Principles, Photosensitizers, Applications, and Future Directions

Exploring the synergy between bioluminescence and nanomaterials: Innovations in analytical and therapeutic applications

The application of bioluminescent luciferin-luciferase systems for visualizing and stimulating various processes in living systems is of great interest due to its specific nature and high signal-to-noise ratio. Nanomaterials can finely manipulate multiple parameters of the bioluminescent systems, including the enzyme stability, intensity, and duration of the irradiation. Also, bioluminescence can affect the properties of a nanomaterial, namely, to carry out BRET, to trigger cascades of various photochemical transformations. Here we summarize cases of the interplay between nanomaterials and various bioluminescent systems to improve various biosensors, biovisualization in cellulo, in vivo, and for therapy over the past twenty years. We reviewed interactions between a wide range of nanomaterials and bioluminescent systems, including bacterial and genetically encoded luciferases. This review aims to serve as a comprehensive guide for developing bioluminescent multimodal nanoplatforms for analytic applications and therapy.

"From darkness to radiance": Light-induced type I and II ROS-mediated apoptosis for anticancer effects of dansylpiperazine-bearing squaraine dyes

Photodynamic therapy relies on the generation of cytotoxic effects triggered by the irradiation of a photosensitizer molecule, resulting in the production of reactive oxygen species at concentrations exceeding physiological levels. In this context, squaraine dyes, a prominent family of second-generation photosensitizers, have gained increasing attention for their remarkable properties, with their photobiological characteristics recently emerging as a key focus of in-depth research. Dansylpiperazine-bearing squaraine dyes exhibited strong absorption in the red visible spectral region, excellent photostability, and a predicted ability to interact with human serum albumin, potentially serving as a transport vehicle to target sites. Benzothiazole derivatives excelled in photodynamic activity, demonstrating 7- to 11-fold increased cytotoxicity upon irradiation against prostate adenocarcinoma PC-3 cells and tumor selectivity indices exceeding 10 when compared to normal NHDF cells. In contrast, the introduction of the dansylpiperazino group in indole-derived compounds unexpectedly declined their photodynamic activity. Concerning benzothiazole-based ones, multiple reactive oxygen species were shown to contribute to the photodynamic effects, with singlet oxygen playing a key role. Squaraine internalization was observed in various cytoplasmic organelles, including mitochondria, endoplasmic reticulum, and lysosomes, without clear evidence of preferential localization to any single organelle. Non-genotoxic in the dark, the squaraines induced cell death by apoptosis upon light activation, as evidenced by significant DNA fragmentation and increased caspase 3/7 activation, particularly for the dye with N-ethyl chains, at concentrations below 1.0 μM, underscoring their potency. Checkpoint arrests in G1 and G2/mitosis were observed for non-irradiated and irradiated conditions, respectively, highlighting the antiproliferative effects of these squaraine dyes.

Nanomedicines as disruptors or inhibitors of biofilms: Opportunities in addressing antimicrobial resistance

The problem of antimicrobial resistance (AMR) has caused global concern due to its great threat to human health. Evidences are emerging for a critical role of biofilms, one of the natural protective mechanisms developed by bacteria during growth, in resisting commonly used clinical antibiotics. Advances in nanomedicines with tunable physicochemical properties and unique anti-biofilm mechanisms provide opportunities for solving AMR risks more effectively. In this review, we summarize the five "A" stages (adhesion, amplification, alienation, aging and allocation) of biofilm formation and mechanisms through which they protect the internal bacteria. Aimed at the characteristics of biofilms, we emphasize the design "THAT" principles (targeting, hacking, adhering and transport) of nanomedicines in their interactions with biofilms and internal bacteria. Furthermore, recent progresses in multimodal antibacterial nanomedicines, including biofilms disruption and bactericidal activity, and the types of currently available antibiofilm nanomedicines contained organic and inorganic nanomedicines are outlined and highlighted their potential applications in the development of preclinical research. Last but not least, we offer a perspective for the effectiveness of nanomedicines designed to address AMR and challenges associated with their clinical translation.

Exosome/liposome hybrid nanovesicles for enhanced phototherapy and boosted anti-tumor immunity against melanoma

Although phototherapy shows great potential as a safe ablative modality for treatment of cutaneous melanoma, there remain serious flaws restricting its therapeutic outcomes, such as cellular resistance against apoptosis, tumor hypoxia, rewritten cellular metabolism and abnormal angiogenesis. To cope with these challenges, this work combines hemin and IR780 (phototherapy agent) and designs an orchestrated liposome/macrophage-derived exosome hybrid delivery system (named IHEL) for tumor-specific delivery of these two drugs and synchronous tumor microenvironment (TME) reprogramming. As the experimental data suggest, by triggering iron overload and up-regulating HMOX-1, hemin drives a shift from an apoptosis-dominant anti-cancer mode to a combined ferroptosis/apoptosis mode of IR780 treatment, which helps to avoid apoptosis resistance. Also, the catalase-like activity of hemin strengthens PDT effect by alleviating hypoxia. In addition to the above-mentioned enhanced direct cell-killing effect, IHEL also provokes anti-cancer immunity by triggering immunogenic cell death (ICD), intervening glycometabolism and polarizing tumor-associated macrophages (TAMs) in TME to M1-type. This work strongly demonstrated the rationality of IR780/hemin combination and delicately designed immunostimulatory nanocarriers for their tumor-specific delivery, providing both theoretical foundation and practical strategies for advanced anti-cancer phototherapy.

NIR pH-Responsive PEGylated PLGA Nanoparticles as Effective Phototoxic Agents in Resistant PDAC Cells

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers worldwide due to its resistance to conventional therapies that is attributed to its dense and acidic tumor microenvironment. Chemotherapy based on gemcitabine usually lacks efficacy due to poor drug penetration and the metabolic characteristics of the cells adapted to grow at a more acidic pHe, thus presenting a more aggressive phenotype. In this context, photodynamic therapy (PDT) offers a promising alternative since it generally does not suffer from the same patterns of cross-resistance observed with chemotherapy drugs. In the present work, a novel bromine-substituted heptamethine-cyanine dye (BrCY7) was synthesized, loaded into PEG-PLGA NPs, and tested on the pancreatic ductal adenocarcinoma cell line cultured under physiological (PANC-1 CT) and acidic (PANC-1 pH selected) conditions, which promotes the selection of a more aggressive phenotype. The cytotoxicity of BrCY7-PEG-PLGA is dose-dependent, with an IC50 of 2.15 µM in PANC-1 CT and 2.87 µM in PANC-1 pH selected. Notably, BrCY7-PEG-PLGA demonstrated a phototoxic effect against PANC-1 pH selected cells but not on PANC-1 CT, which makes these findings particularly relevant since PANC-1 pH selected cells are more resistant to gemcitabine as compared with PANC-1 CT cells.

Luminescent Iridium-Peptide Nucleic Acid Bioconjugate as Photosensitizer for Singlet Oxygen Production toward a Potential Dual Therapeutic Agent

A novel bioorganometallic PNA conjugate (Ir-PNA) was synthesized by covalently bonding a model PNA tetramer to a luminescent bis-cyclometalated Ir(III) complex that acted as a photosensitizer under light irradiation to generate singlet oxygen (1O2). The conjugate was prepared using an Ir complex bearing the 1,10-phenanthroline ligand functionalized with either a free primary amine (Ir-NH2) or a carboxyl group (Ir-COOH) for the conjugation to PNA. The photophysical studies on the Ir-COOH and the Ir-PNA demonstrated that the luminescent properties were maintained after the conjugation of the Ir fragment to PNA. Furthermore, the abilities to produce 1O2 of Ir-COOH and Ir-PNA were confirmed in a cuvette under visible light irradiation employing 1,5-dihydroxynaphthalene as a reporter, and the measured singlet oxygen quantum yield (ΦΔ) supported the Ir-PNA conjugate efficacy as a photosensitizer (ΦΔ = 0.54). Two-photon absorption microscopy on HeLa cells revealed that Ir-PNA localized in both the cytosol and nucleus, suggesting its potential as an intracellular carrier for PNA. Cytotoxicity assays by MTT tests showed that Ir-PNA was nontoxic in the absence of light, but induced cell death (EC50 = 18 μM) after UV irradiation. Overall, the Ir-PNA conjugate represents a promising system for the intracellular delivery of the PNA and its application in PDT.

Rationally Designed Ir(III) Complex with an Exceptionally Strong Binding to Human Serum Albumin for Targeted Photodynamic Therapy

The application of iridium(III) complexes in photodynamic therapy (PDT) is often limited by their poor selectivity for cancerous cells, necessitating high drug doses that increase the risk of side effects. The development of efficient drug delivery systems such as albumin conjugation is therefore crucial to enhance the tumor-targeted delivery of photosensitizers. To date, the vast majority of metal complexes exhibit weak to moderate binding with human serum albumin, limiting the feasibility of this approach. To overcome this limitation, the rational design through molecular docking and density functional theory calculations of a novel Ir(III) complex as a strong albumin-binding photosensitizer is described. The herein reported compound has the highest albumin binding constant ever reported for an iridium complex, and it showed to photocatalytically produce reactive oxygen species upon blue light irradiation. The presented compound as well as structural derivatives could have high potential in tumor-targeted photodynamic therapy.

Thionated Coumarins: Study of the Intersystem Crossing and the Zero-field Splitting of the Triplet State Using Time-Resolved Transient Optical and Electron Paramagnetic Resonance Spectroscopies

To study the effect of thionation of the carbonyl groups in a chromophore, i. e. replacing the O atom with S atom, on the photophysics, we studied two thionated coumarin derivatives (Cou-S and Cou-6-S) with various steady state and transient spectroscopic methods. Both compounds exhibit red-shifted absorption (up to 4900 cm-1) and strong fluorescence quenching as compared to the unthionated analogues. Femtosecond transient absorption spectra show fast ISC (ca. 10 ps) in the thionated coumarin derivatives, while negligible ISC was observed in the unthionated coumarin. Interestingly, triplet excited state lifetimes of the thionated coumarin (0.14 μs) is much shorter than the unthionated analogues (53.4 μs). Time-resolved electron paramagnetic resonance (TREPR) spectra indicate much larger zero field splitting (ZFS) D parameters (up to 0.287 cm-1) for the T1 state of the thionated coumarins than the unthionated analogues (D=0.1001 cm-1). This large D value is attributed to the strong spin orbital coupling effect. These results demonstrate the advantage and the drawback of thionation-enhanced ISC, i. e. the ISC is efficient, but triplet state lifetimes become substantially shorter. This information is useful for the future design of heavy atom-free triplet photosensitizers for photodynamic therapy, photon upconversion, photocatalytic organic synthesis and photopolymerization, etc.

Recent advances in gold nanoparticle-graphene hybrid nanoplatforms with visible to near-infrared response for photodynamic and photothermal therapy and bioimaging

Photodynamic therapy (PDT) and photothermal therapy (PTT) are light-activated cancer treatments. PDT involves the administration of a photosensitizing agent, which is activated by light of a specific wavelength to generate reactive oxygen species. Alternatively, PTT involves the use of photothermal agents, which are materials that absorb light and convert it into heat. Gold nanoparticles are often used as photothermal agents owing to their localized surface plasmon resonance (LSPR), a key optical property, which allows them to efficiently absorb light and convert it into heat. Graphene, which is a 2D material with extraordinary optical and physical properties and a large surface area, shows great promise both in PDT and PTT as an intrinsic nanoheater or a versatile platform for the immobilization of gold nanoparticles and other functional molecules, including photosensitizers. Moreover, graphene-based derivatives, i.e. graphene oxide (GO) and reduced graphene oxide (rGO), exhibit intrinsic optical/spectroscopic signals, which can be used in fluorescence, Raman and thermal imaging. By combining gold nanoparticles with graphene derivatives, a higher increase in temperature can be achieved under light irradiation owing to the synergistic effect of these two materials and the drug delivery efficiency and multimodal imaging techniques can be enhanced. This review provides insights into graphene-based nanoplatforms, focusing on multimodal therapy and imaging techniques. Furthermore, future perspectives in the field of graphene-based- and hybrid-nanoplatforms are suggested.

Zirconium Dental Implants as Potential Optical Waveguides in Photodynamic Inactivation of Bacterial Biofilms-A Pilot Study

In patients with predisposing risk factors, bacterial colonization of dental implants can lead to periimplantitis (PI). Established individual treatment protocols can be effective, but antimicrobial resistance (AMR) and biofilm formation may impede successful treatment, therefore requiring surgical intervention. Photodynamic Inactivation (PDI) combined with optical waveguides could eradicate such pathogens without the risk of new AMR emergence and reduce the need for surgery. In this pilot study, we investigated the waveguiding function of light-transmitting zirconium dioxide (ZrO2) dental implants of different diameters by quantifying their transmission spectrum, fraction of transmitted red-light intensity, and potential polarizing properties. In addition, PDI experiments involving in vitro grown Staphylococcus epidermidis biofilms on ZrO2 and titanium alloy (TAV) discs were performed. Colonized discs were treated with Methylene Blue (MB) photosensitizer before red-light illumination (670 nm) at various intensities. A reduction in bacterial colony-forming units (CFUs) of up to 85% was observed on ZrO2 discs. Meanwhile, the biofilms grown on TAV discs showed no significant reduction in CFUs. These findings make ZrO2 a potential candidate in augmentative PDI treatment of PI. The successful use of PDI combined with waveguiding ZrO2 dental implants can support the reduction in antibiotic prescriptions, thus advancing the WHO's One Health approach of antibiotic stewardship.

Activatable Photosensitizers: From Fundamental Principles to Advanced Designs

Photodynamic therapy (PDT) is a promising treatment that uses light to excite photosensitizers in target tissue, producing reactive oxygen species and localized cell death. It is recognized as a minimally invasive, clinically approved cancer therapy with additional preclinical applications in arthritis, atherosclerosis, and infection control. A hallmark of ideal PDT is delivering disease-specific cytotoxicity while sparing healthy tissue. However, conventional photosensitizers often suffer from non-specific photoactivation, causing off-target toxicity. Activatable photosensitizers (aPS) have emerged as more precise alternatives, offering controlled activation. Unlike traditional photosensitizers, they remain inert and photoinactive during circulation and off-target accumulation, minimizing collateral damage. These photosensitizers are designed to "turn on" in response to disease-specific biostimuli, enhancing therapeutic selectivity and reducing off-target effects. This review explores the principles of aPS, including quenching mechanisms stemming from activatable fluorescent probes and applied to activatable photosensitizers (RET, PeT, ICT, ACQ, AIE), as well as pathological biostimuli (pH, enzymes, redox conditions, cellular internalization), and bioresponsive constructs enabling quenching and activation. We also provide a critical assessment of unresolved challenges in aPS development, including limitations in targeting precision, selectivity under real-world conditions, and potential solutions to persistent issues (dual-lock, targeting moieties, biorthogonal chemistry and artificial receptors). Additionally, it provides an in-depth discussion of essential research design considerations needed to develop translationally relevant aPS with improved therapeutic outcomes and specificity.

Redox disruption using electroactive liposome coated gold nanoparticles for cancer therapy

Cancer remains a global health challenge necessitating innovative therapies. We introduce a strategy to disrupt cancer cell redox balance using gold nanoparticles (Au NPs) as electron sinks combined with electroactive membranes. Utilizing Shewanella oneidensis MR-1 membrane proteins, we develop liposomes enriched with c-type cytochromes. These, coupled with Au NPs, facilitate autonomous electron transfer from cancer cells, disrupting redox processes and inducing cell death. Effective across various cancer types, larger Au NPs show enhanced efficacy, especially under hypoxic conditions. Oxidative stress from Au@MIL (MIL: membrane-integrated liposome) treatments, including mitochondrial and endoplasmic reticulum lipid oxidation and mitochondrial membrane potential changes, triggers apoptosis, bypassing iron-mediated pathways. Surface plasmon band and X-ray absorption near-edge structure (XANES) analyses confirm electron transfer. A SiO2 insulator coating on Au NPs blocks this transfer, suppressing cancer cell damage. This approach highlights the potential of modulated electron transfer pathways in targeted cancer therapy, offering refined and effective treatments.

Theoretical basis of all-optical modulation of a probe laser beam due to photothermal modulation of the aggregation state in organic dyes, with experimental proof of the principle

The inherent potential for self-assembly is a well-known attribute of organic dye molecules. This work takes advantage of the changes in dye photochemical and photophysical properties produced by the aggregation phenomenon, to investigate the behavior of all-optical modulation in molecular aggregates. The theoretical principles for a dual beam all-optical modulation, as well as the conception of an optical logic gate by exploring the aggregation phenomenon are discussed throughout the article. The deposition of heat by an excitation laser beam in a dye sample induces the dissociation of the self-assembled species, which modulates the dye transparency at the spectral absorption range of the aggregates and, simultaneously, modulates the darkness at the monomer spectral absorption range, because the dissociation of an aggregate of order n potentially produces n monomer units. Experimental proof of the principles was performed by using the methylene blue dye and two laser beams in a pump-probe configuration. The laser wavelength used to excite or to probe the absorption of the aggregated species was 532 nm. To excite or to probe the monomer absorption band, a diode laser at 663 nm wavelength was used. When probing the sample with the 532 nm green laser beam, an in-phase signal modulation was obtained. Within such conditions, an optical gate could be conceived allowing the Boolean operation A·B. When probing the sample with the 663 nm red laser beam, an inverted signal modulation was obtained, which allowed the Boolean operation A¯·B. The achievable signal modulation amplitudes for methylene blue and toluidine blue dyes were measured and compared.

Signature of click chemistry in advanced techniques for cancer therapeutics

Click chemistry has made a revolution in the field of chemical biology owing to its high efficiency, specificity, and mild reaction conditions. The copper(i)-catalyzed azide-alkyne cycloaddition (CuAAC) and strain-promoted [3 + 2] azide-alkyne cycloaddition (SPAAC) stand out as the most popular click reactions that construct a stable triazole ring by reacting an azide with an alkyne. These two reactions represent an ideal choice for biological applications due to its specificity, reliability, and biocompatibility. As a powerful modular synthetic approach for creating new molecular entities, it has seen increasing use in anticancer drug discovery. The present "state of the art" focuses mainly on the signature of click chemistry (CuAAC and SPAAC) in advanced techniques for cancer therapeutics, which includes cancer immunotherapy, antibody-drug conjugates, development of proteolysis-targeting chimeras, targeted dual-agent combination therapy for cancer, exosome modification for cancer therapy, and photodynamic therapy (PDT).

Inflammation-targeted nanomedicine prevents tumor metastasis following photodynamic therapy by reversing epithelial-mesenchymal transition and ROS-mediated immunosuppression

BACKGROUND

Prolonging the duration of photodynamic therapy (PDT) enhances the level of reactive oxygen species (ROS), thereby facilitating tumor ablation. However, our findings indicated that excessive ROS not only induces epithelial-mesenchymal transition (EMT) but also creates an immunosuppressive microenvironment in tumor, thereby triggering tumor metastasis.

METHODS

We initially developed neutrophil membrane hybrid liposomes (NLs) that can specifically target inflamed tumor tissues following PDT. Then, we utilized NLs to encapsulate the antioxidant nanozyme FeGA and the antiplatelet drug Lysine Acetylsalicylate (LAS), resulting in the formulation NLASF.

RESULTS

Experimental results demonstrated that FeGA effectively scavenges ROS, thereby reversing the immunosuppressive microenvironment induced by prolonged PDT. Furthermore, the incorporation of LAS effectively disrupts the interaction between tumor cells and platelets, mitigating tumor EMT and inhibiting hematogenous tumor metastasis. In a breast cancer mouse model, we observed that treatment with NLASF led to a near-complete suppression of tumor lung metastasis following the prolonged PDT. Additionally, the in vivo application of NLASF did not result in any blood toxicity or organ toxicity, highlighting its significant advantages over the free drugs group.

CONCLUSIONS

This study provides a novel approach to enhance the efficacy of PDT and successfully suppress PDT-mediated tumor metastasis.

Water-soluble BODIPY dyes: a novel approach for their sustainable chemistry and applied photonics

The BODIPY family of organic dyes has emerged as a cornerstone in photonics research development, driving innovation and advancement in various fields of high socio-economic interest. However, the majority of BODIPY dyes exhibit hydrophobic characteristics, resulting in poor solubility in water and other hydrophilic solvents. This solubility is paramount for their optimal utilization in a myriad of photonic applications, particularly in the realms of biology and medicine. Furthermore, it facilitates safer and more sustainable manipulation and chemical modification of these expansive dyes. Nevertheless, bestowing BODIPYs with water solubility while preserving their other essential properties, notably their photophysical signatures, poses a significant challenge. In this context, we present a straightforward general chemical modification aimed at converting conventional hydrophobic BODIPYs into highly hydrophilic variants, thus enabling their efficient solubilization in water and other hydrophilic solvents with minimal disruption to the dye's inherent photophysics. The efficacy of this methodology is demonstrated through the synthesis of a number of water-soluble BODIPY dyes featuring diverse substitution patterns. Furthermore, we showcase their utility in a spectrum of photonics-related applications, including in-water BODIPY chemistry and dye-laser technology, and fluorescence microscopy.

Future Prospects and Regulatory Pathways for Invasome Technologies in Transdermal Drug Delivery

Skin is one of the largest organs in the human body. It acts as an outer protective cover and comprises the epidermis, dermis, and hypodermis. Liposomes are formed by phospholipids and have a vesicular character that improves the encapsulation of lipophilic, hydrophilic, and amphiphilic drugs. The invasome structure is flexible as opposed to regular liposomes; this is due to the presence of ethanol and terpene that increases lipid fluidity in the vesicle structure. Terpenes, ethanol, or terpene mixes are potential carriers that invasomes' tiny liposomal vesicles used to improve skin penetration. Terpenes that are primarily derived from natural sources are the most efficient and secure kind of penetration enhancers (PEs). There are some methods for the preparation of invasomes, but mostly the techniques used for the preparation of invasomes are mechanical dispersion and film hydration methods. Although PEs are effective when applied topically, only a small number are clinically approved due to concerns about skin irritation and toxicity. Invasomes exhibit a higher rate of skin penetration than liposomes and ethosomes. This review examines the structure, components, preparation methods, and applications of invasomes in pharmaceutical formulations, focusing on their potential to treat skin disorders and improve therapeutic outcomes. The primary objective is to assess the future potential of invasome technologies in transdermal drug delivery, alongside an exploration of the regulatory challenges and pathways for their development and approval. Graphical abstract illustrating the composition, mechanism of action, and therapeutic applications of invasomes in transdermal drug delivery systems.

Novel ꞵ-carboline/cyanoisoflavone photosensitizers for ferroptosis-induced efficient chemo-photodynamic synergistic cancer therapy

Photodynamic therapy (PDT) is an emerging therapeutic modality to selectively eradicate pathological cells, such as cancer cells. Hence, we designed and synthesized a series of novel ꞵ-carboline/cyanoisoflavone photosensitizers A1-A3. All compounds possessed potent type-I/-II photodynamic properties. Especially, the optimized compound A2 produced large amounts of •O2-, •OH, and 1O2 under irradiation, and exhibited a higher quantum yield of singlet oxygen (ΦΔ = 0.92) than others. Furthermore, A2 not only exhibited potent cytotoxicity in HT29 cells, but also demonstrated prominent chemo-photodynamic effects with IC50 values of 3.9-4.1 μM under normoxic and hypoxic conditions in HT29 cells, while exhibited minimal toxicity to normal cells, suggesting its tumor-selective and hypoxia-tolerant efficacy. Most importantly, A2 significantly promoted mitochondrial damage and ferroptosis, through depleting GSH/GPX-4 levels and increasing malondialdehyde (MDA) expression. Finally, in vivo studies showed that A2 achieved a high colonic tumor-inhibitory rate of 84.6 % through chemo-photodynamic therapy. These findings provide a promising framework for the development of novel photosensitizers for chemo-photodynamic therapy.

Albumin Modulated Homodimer as an Efficient Photosensitizer for Long-Term Imaging-Guided Tumor Therapy Directed with Sunlight Irradiation

The reactive oxygen species (ROS) amplification caused by inevitable plasma albumin encapsulation is still a challenge to circumvent the systemic adverse effects in the photodynamic therapy (PDT) process. Herein, a disulfide bond linked homodimer, Cy1280, which is modulated by albumin to accurately balance the fluorescence and ROS generation and exhibit a weak fluorescence and sealed PDT effect during blood circulation, is exploited. Cy1280 can be specifically internalized and dispersed at the tumor site via Organic Anion Transporter Proteins (OATPs) and thiol-disulfide exchange mediated synergistic uptake and activated after mild sunlight irradiation (100 ± 5 Klx) to sensitize neighboring oxygen in cellular mitochondria to execute direct protein dysfunction effect. The dynamic covalent chemistry (DCC) facilitates prolonged and sustained retention in tumors (>336 h) and demonstrates the efficacy of imaging-guided solid-tumor therapy in tumor-bearing BALB/C mice. This study resolves the inevitable stubborn impotent tumor penetration caused by bulky-sized nanoparticles and high interstitial pressure of tumor with synergistic uptake manner, the long-term circulation and sealed PDT manipulated with albumin also improve the whole body phototoxic symptom. The advantageous feature of Cy1280 provides a promising candidate for overcoming the off-target phototoxicity and inadequate accumulation challenges in clinical translation with photosensitizers (PSs).

pH-Sensitive Porphyrin Metal-Organic Frameworks for Controlled Delivery of Para-Toluenesulfonamide and Photodynamic Cancer Therapy

Introduction

Photodynamic therapy (PDT) is a promising approach for tumor treatment. PDT for treating lung squamous cell carcinoma (LSCC) under the guidance of bronchoscopy has great potential for development. However, the use of high-intensity lasers in treatment may pose a risk of tissue damage. To address this issue, enhancing the sensitivity of tumor tissue to phototherapy is highly valuable.

Methods

In this study, a simple method was employed to prepare porphyrin-metal framework nanoparticles (NPs), referred to as HA-PTS@PCN. The design of these NPs is based on the concept of tumor sensitization, constructed with the porphyrin-based metal-organic framework compound PCN-224 to load the drug para-toluenesulfonamide (PTS).

Results

Multiple experiments have demonstrated that these NPs can be effectively absorbed and selectively release PTS within the acidic tumor microenvironment. Under 660 nm laser irradiation, the material releases reactive oxygen species, demonstrating effective photodynamic therapeutic effects. Additionally, due to the tumor-sensitizing properties of PTS, the treatment efficacy of these NPs on LSCC is significantly greater than that of PCN-224 alone. Both in vitro and in vivo studies confirmed that combining tumor sensitization strategies with PDT therapy for LSCC significantly enhances anticancer effects.

Discussion

This study provides a universal strategy for preparing drug-loaded PDT nanoplatforms and offers a new approach for developing nanomedicine with tumor-sensitizing effects.

Exploring the phototherapy modalities and dosages for an ingestible light-emitting diode capsule to eliminate Helicobacter pylori infection

Helicobacter pylori (H. pylori) infection presents increasing challenges to antibiotic therapies owing to limited drug bioavailability, multi-drug resistance and collateral damage to commensal intestinal microflora. To address these problems, here, an ingestible magnetically controlled light-emitting diode (LED) light source was designed for an ingestible capsule to perform antimicrobial photodynamic therapy (aPDT) without an exogenous photosensitizer (ex-PS) at 630 nm. Specifically, we first optimized the antibacterial rates of aPDT with ex-PS and aPDT without ex-PS against H. pylori at the bacterial suspension level by varying the wavelength (405, 530, 630 nm), photosensitizer concentration (2, 4, 6, 8, 10 μg/mL), power density (15, 30 mW/cm2), and energy density (0, 3.6, 7.2, 10.8, 14.4, 18.0 J/cm2). Then, we compared the antibacterial effect of aPDT with ex-PS and aPDT without ex-PS against H. pylori at the biofilm level, revealing that the antibacterial rate of aPDT without ex-PS reached approximately 97 % at 405 nm and 18 J/cm2, similar to that of aPDT with ex-PS under the same conditions. Furthermore, 80 SD rats infected with H. pylori were treated with aPDT with ex-PS and aPDT without ex-PS at the above wavelengths. Histopathological analysis of rat gastrointestinal tissues revealed that aPDT with ex-PS and aPDT without ex-PS exhibited significant antibacterial activity against H. pylori, without side effects on normal tissues. Additionally, aPDT without ex-PS at 630 nm induced an anti-inflammatory response and regulated the intestinal flora. Ultimately, we developed a magnetically controlled LED capsule for in vivo aPDT without ex-PS at 630 nm against H. pylori.

Regio-isomerization Optimization Strategy for Photosensitizers: Achieving Ultrahigh Type I Reactive Oxygen Species Generation to Enhance Cancer Photoimmunotherapy

Phototherapy, renowned for its noninvasiveness, is widely employed in tumor treatment. However, the tumor microenvironment is usually hypoxic, with insufficient reactive oxygen species (ROS) production, severely limiting its application. Herein, we introduce a regio-isomerization optimization strategy and have synthesized four regio-isomeric photosensitizers featuring a donor-acceptor (D-A) configuration by tactically varying the linkage sites between D and A. Among them, TAF-3 with excellent photostability has an ultrahigh type I ROS production efficiency (4.79 times that of methylene blue) and a photothermal conversion efficiency of 41.7%. TAF-3 improves the conjugation degree; produces an appropriate intramolecular charge transfer effect, which enhances its optical properties and phototherapeutic efficiency; and promotes a stronger immune cell death effect, reducing postoperative melanoma recurrence by 60%. Overall, the optical attributes of D-A type photosensitizers can be tailored through the precision modulation of regio-isomerization, offering a promising avenue for the advancement of clinical photosensitizers suitable for phototherapy.

The Role of Inorganic Nanomaterials in Overcoming Challenges in Colorectal Cancer Diagnosis and Therapy

Colorectal cancer poses a significant threat to human health due to its high aggressiveness and poor prognosis. Key factors impacting patient outcomes include post-surgical recurrence, chemotherapeutic drug resistance, and insensitivity to immunotherapy. Consequently, early diagnosis and the development of effective targeted therapies are essential for improving prevention and treatment strategies. Inorganic nanomaterials have gained prominence in the diagnosis and treatment of colorectal cancer owing to their unique size, advantageous properties, and high modifiability. Various types of inorganic nanomaterials-such as metal-based, metal oxide, quantum dots, magnetic nanoparticles, carbon-based, and rare-earth nanomaterials-have demonstrated significant potential in enhancing multimodal imaging, drug delivery, and synergistic therapies. These advancements underscore their critical role in improving therapeutic outcomes. This review highlights the properties and development of inorganic nanomaterials, summarizes their recent applications and progress in colorectal cancer diagnosis and treatment, and discusses the challenges in translating these materials into clinical use. It aims to provide valuable insights for future research and the clinical application of inorganic nanomaterials in colorectal cancer management.

Pulsed cavitation ultrasound assisted delivery of cardamom, pistacia and laurel encapsulated micelles nanoparticles for sono-photodynamic lymphoma in vitro and in vivo treatment

Sono-photodynamic therapy (SPDT) has attracted a lot of interest as a cutting-edge therapeutic strategy in the field of cancer treatment. The essential part of SPDT is the sensitizer, which under laser photon and pulsed cavitation ultrasound sono-irradiation may transform sono and photo- energy into cytotoxic molecules. Photon absorption, targeting, penetration, and oxygen dependence remain challenges in sono- -photosensitizer (SPs) design. Rapid advancements in material science have prompted the creation of several SPs that create cytotoxic species with great selectivity, safety, and noninvasiveness for the treatment of tumors. The current study aims to provide an advanced method of activated cancer treatment by using pulsed cavitation to assist the delivery of cardamom, pistacia and laurel conjugated micelles nanoparticles (CPL-Micelle NP) for the sono-photodynamic lymphoma in vivo and in vitro treatment. Human lymphoma cells (U-937) were used in the in vitro study, and the in vivo application groups of the study protocol were Swiss albino mice treated with 9,10-Dimethyl-1,2-Benzanthracene (DMBA) only; they were not given any treatment to induce lymphoma. The study treatment protocol started only after lymphoma induction, and involved daily administration of CPL-Micelle NP as SPDT sensitizer whether or not to be exposed to photo- (IRL) or sono- (US) or a combination of them for three minutes for a period of two weeks. Indicated that Micelle NP is a useful CPL delivery mechanism that targets lymphoma cells directly. Furthermore, CPL-Micelle NP is a promising SPS that, when used in conjunction with SPDT, can be very effective in in vitro treating lymphoma-U-937 (in a dose-dependent manner cell viability declined, an increase in the cells population during the S and G2/M phases indicates that the cell cycle was arrested, and an increase in cell population in the Pre-G, autophagic cell death, as well as necrosis and early and late apoptosis, indicate that cell death was induced) and DMBA-Lymphoma-induced mice in vivo (induced antiproliferative genes, repressed antiangiogenic and antiapoptotic genes), successfully slowing the growth of tumors and even killing cancer cells, as well as lowering oxidative stress malondialdehyde (MDA), improving the functions of the kidneys, liver, and enzymatic and non enzymatic antioxidants. SPDT, the photo- or sono- chemical CPL activation mechanism, and the antioxidant capacity of non-activated CPL can all be linked to this process. On the bases of the findings, CPL-Micelle NP shows a great promise as a novel, efficient selective delivery system for localized SPDT-activated lymphoma treatment.

Successful treatment of a patient with multiple solar keratosis (AK) with highly differentiated squamous cell carcinoma across the face through the combination of operation and photodynamic therapy: A case report

Actinic keratosis (AK) with multiple lesions on the face combined with well-differentiated squamous cell carcinoma is a severe skin lesion. Traditional treatment methods mainly rely on surgery. However, for a 92-year-old female patient, due to her advanced age and poor physical condition, traditional surgical treatment may bring significant risks and complications, such as postoperative infection and poor healing. Moreover, it is impossible to completely remove all AK lesions on the face through surgery, and surgical treatment may have a significant impact on the patient's appearance, potentially leading to facial scars, pigmentation, and other issues, which can seriously affect the patient's quality of life. Photodynamic therapy (PDT), as an emerging treatment method, can not only effectively reduce the size of the lesions but also improve the skin texture and color to some extent, offering a dual benefit. In this unique case, photodynamic therapy combined with surgery was successfully used to treat a 92-year-old female patient with multiple facial actinic keratoses (AK) and well-differentiated squamous cell carcinoma. The successful treatment of this case provides valuable reference for research in this field. However, the application of photodynamic therapy in treating complex skin lesions in elderly patients is still in the exploratory stage, and its long-term efficacy and safety are worth further investigation through clinical trials.

Highly efficient tumor oxygen supplementation MnO2 nano-MOF encapsulated Sorafenib for multiple synergistic CDT/PDT/RT

Tumor growth often creates hypoxic conditions within the tumor microenvironment, which can limit the effectiveness of therapies. To address this issue, a novel "all-in-one" nanoplatform called PCN-224(Hf)@Sorafenib@(PSM) has been developed. This nanoplatform utilizes PCN-224(Hf)-modified MnO2 and combines various therapeutic modalities-chemotherapy, chemodynamic therapy (CDT), photodynamic therapy (PDT), and radiotherapy (RT)-to enhance treatment efficacy. In the PSM nanoplatform, MnO2 decomposes H2O2 to produce oxygen (O2) and reacts with glutathione (GSH) to form Mn2+. This process catalyzes a Fenton-like reaction that generates hydroxyl radicals (·OH), facilitating CDT. When exposed to 635 nm light irradiation, the porphyrin ligand in PCN-224(Hf) produces singlet oxygen (1O2), while the Hf6 clusters contribute to the PDT effects. Furthermore, the nanoplatform enhances radiotherapy by harnessing high-energy radiation. Studies have demonstrated that PSM effectively kills solid tumors even in hypoxic conditions and significantly inhibits tumor growth. This innovative nanoplatform showcases high efficacy in multimodal synergistic tumor treatment, successfully integrating multiple therapeutic approaches to overcome the challenges posed by hypoxia.

Current landscape of metal-organic framework-mediated nucleic acid delivery and therapeutics

Nucleic acid drugs utilize DNA or RNA molecules to modulate abnormal gene expression or protein translation in cells, enabling precise treatment for specific conditions. In recent years, nucleic acid drugs have demonstrated tremendous potential in vaccine development and treating genetic disorders. Currently, the primary carriers for clinically approved nucleic acid therapies include lipid nanoparticles and viral vectors. Beyond that, metal-organic frameworks (MOFs) are highly ordered, porous nanomaterials formed through the self-assembly of metal ions and organic ligands via coordination bonds. Their porosity structure offers great loading efficiency, stability, tunability, and biocompatibility, making them an attractive option for nucleic acid delivery. Given the research on MOFs as nucleic acid carriers has garnered significant attention in recent years, this review provides an overview of the therapeutic strategies and advancements in MOF-mediated nucleic acid delivery. The unique properties of various MOF carriers are introduced, and different approaches for nucleic acid loading are parallelly compared. Moreover, a systematic classification based on the type of nucleic acid cargo loaded in MOFs and corresponding applications is thoroughly described. This summary outlines the unique mechanisms through MOFs enhance nucleic acid delivery and emphasizes their substantial impact on therapeutic efficacy. In addition, the utilization of MOF-mediated nucleic acid treatment in combination with other therapies against malignant tumors is discussed in particular. Finally, an outlook on the challenges and potential opportunities of this technology in future translational production and clinical implementation is presented and explored.

Harnessing the power of inorganic nanoparticles for the management of TNBC

Triple-negative breast cancer (TNBC) is a highly aggressive and metastatic form of breast cancer characterized by the absence of hormonal receptors with a poor prognosis and limited treatment options. Addressing this challenge has become an urgent priority, driving substantial scientific efforts in this area. In recent years, inorganic nanoparticles have emerged as promising agents for the therapeutic and diagnostic management of this malignancy. Their unique physicochemical properties such as exceptional stability, uniform size, ease of surface functionalization, and distinctive optical and magnetic characteristics have positioned them as highly attractive candidates for these applications. This review primarily focuses on the therapeutic and diagnostic applications of inorganic nanoparticles, summarizing key research findings that demonstrate their efficacy against TNBC. Additionally, it addresses the toxicological concerns associated with these nanoparticles and explores advanced strategies to mitigate their adverse effects, thereby improving their clinical utility. Finally, the review concludes with a concise discussion of the prospects of these nanoparticles in biomedicine.

The Combination of Active-Targeted Photodynamic Therapy and Photoactivated Chemotherapy for Enhanced Cancer Treatment

Scientists have been actively investigating novel therapies that can effectively eradicate cancer cells with negligible side effects in normal tissues when used alone or in a combinatorial approach. Photodynamic therapy has emerged as a promising non-invasive therapy that integrates photosensitizer, oxygen, and a specific wavelength of light for the treatment of cancer. Despite encouraging outcomes yielded by PDT, conventional PSs are faced with longstanding challenges such as poor water solubility, a short half-life, and off-target toxicity. Development of nanotherapeutics has shown great potential in overcoming this issue. The tumor microenvironment is inherently hypoxic, and this promotes tumor resistance to PDT, as it is oxygen-dependent. Photoactivated chemotherapy, an oxygen-independent light-based therapy, utilizes chemotherapeutic regimens that remain inert until exposed to light, allowing target-specific activation while minimizing off-target toxicity. Integration of these techniques can improve selectivity and yield synergistic cytotoxic effects that could improve cancer treatment.

Conceptual expansion of photomedicine for spatiotemporal treatment methods

Photomedicine has evolved from basic phototherapy to a broad range of light-based technologies to achieve precise and minimally invasive therapeutic outcomes. Recent advances in light sources, photochemical reactions, and photoswitches have facilitated the development of light-activated methodologies for modulating biological processes. This review discusses the history of light therapy that leads to the emergence of a new field known as photopharmacology, mode of actions in photopharmacology such as photodynamic, photo-uncaging and photoswitchable methods, a few representative examples in photopharmacology, and a brief overview of its associated challenges. The current developments in photopharmacology hold great promise for the treatment of diseases such as cancer, with enhanced therapeutic precision, and minimal side effects. We foresee further expansion of photomedicine for novel approaches in precision medicine and healthcare, and unprecedented treatment methods.

Multicationic ruthenium phthalocyanines as photosensitizers for photodynamic inactivation of multiresistant microbes

Four photosensitizers PS1a-PS4a consisting in multicationic ruthenium(II) phthalocyanines (RuPcs) have been evaluated in photodynamic inactivation (PDI) of multiresistant microorganisms. The RuPcs, bearing from 4 to 12 terminal ammonium salts, have been designed to target the microorganisms cytoplasmic cell membrane and display high singlet oxygen quantum yields. In addition, PS3a and PS4a were conceived to exhibit multi-target localization by endowing them with amphiphilic character, using two different structural approaches. Under low light regimes, the two hydrophilic PS1a and PS2a, as well as the amphiphilic PS3a show much stronger response against Gram-positive MRSA than that observed for the typical phthalocyanines designed for PDI, namely zinc(II) and palladium(II) complexes, as well as free-base Pcs. Besides, PS1a, PS2a and PS3a show remarkably high activity against the Gram-negative E. coli, although weak fungicidal character against fluconazole-resistant C. albicans. Contrasting, the structurally different, amphiphilic PS4a shows only slight activity for Gram-positive bacteria, despite its ability to cross cell membrane and reach internal organelles. Still, PS4a shows a positive synergistic effect against MRSA when combined with doxycycline, exhibiting an increased activity from about 1.5 to about 4.9 log reduction under the light dose of 30 J/cm2 and the 0.125 mg/L subinhibitory dose of doxycycline.

Current Context of Designing Phototheranostic Cyclometalated Iridium (III) Complexes to Open a New Avenue in Cancer Therapy

Photo-induced chemotherapy offers the best option for the selective treatment of cancer among all the prevailing modalities. Iridium (III) complexes, flourished with excellent photophysical and photochemical properties, have been considered to be superior for undergoing photo-responsive cancer therapy. Large Stokes shift, long-lived triplet excited state, photostability, and tuneable emission have rendered its excellence as a phototheranostic agent. In particular, the cyclometalated Ir (III) complexes and their respective nanoparticles have made a strong niche in the arena of cancer therapy. In recent years, Ir (III) based complexes have shown promising utilities as both imaging and therapeutic agents as well. Therefore, this review summarises the recent advances in the strategic designing of cyclometalated Ir(III) complexes to augment their phototheranostic applications in precision medicine.

Systematic review: Mechanisms of photoactive nanocarriers for imaging and therapy including controlled drug delivery

BACKGROUND

The design of smart, photoactivated nanomaterials for targeted drug delivery systems (DDS) has garnered significant research interest due in part to the ability of light to precisely control drug release in specific cells or tissues with high spatial and temporal resolution. The development of effective light-triggered DDS involves mechanisms including photocleavage, photoisomerization, photopolymerization, photosensitization, photothermal phenomena, and photorearrangement, which permit response to ultraviolet (UV), visible (Vis), and/or Near Infrared (NIR) light. This review explores recent advancements in light-responsive small molecules, polymers, and nanocarriers, detailing their underlying mechanisms and utility for drug delivery and/or imaging. Furthermore, it highlights key challenges and future perspectives in the development of light-triggered DDS, emphasizing the potential of these systems to revolutionize targeted therapies.

METHOD

A systematic literature search was performed using Google Scholar as the primary database and information source. We searched the recently published literature (within 15 years) with the following keywords individually and in relevant combinations: light responsive, nanoparticle, drug release, mechanism, photothermal, photosensitization, photopolymerization, photocleavage, and photoisomerization.

RESULTS

We selected 117 scientific articles to assess the strength of evidence after screening titles and abstracts. We found that six mechanisms (photocleavage, photoisomerization, photopolymerization, photosensitization, photothermal phenomena, and photorearrangement) have primarily been used for light-triggered drug release and categorized our review accordingly. Azobenzene/spiropyran-based derivatives and o-nitrobenzyl/Coumarin derivatives are often used for photoisomerization and photocleavage-enabled drug delivery, while free radical polymerization and cationic polymerization comprise two main mechanisms of photopolymerization. One hundred two is the primary active radical oxygen species employed for photosensitization, which is a key factor that impacts the therapeutic effects in Photodynamic therapy, but not in photothermal therapy.

CONCLUSION

The comprehensive review serves as a guiding compass for light-triggered DDS for biomedical applications. This rapidly advancing field is poised to generate breakthroughs for disease diagnosis and treatment.

Chiral helical scaffolds: Unlocking their potential in biomolecular interactions and biomedical applications

In nature, various molecules possess spiral geometry. Such helical structures are even prevalent within the human body, represented classically by DNA and three-dimensional (secondary structure) protein folding. In this review, we chose helicenes and helicene-like structures -synthetically accessible carbon-rich molecules- as a compelling example of helically chiral scaffolds. Helicene chemistry, traditionally anchored in materials science, has been a subject of increasing interest in the biomedical field due to the unique optical and chiral properties of these helical structures. This review explores the diverse applications of helicenes in biomedicine, focusing on their role in cell imaging, protective coatings for implants, drug delivery systems, biosensors, and drug discovery. We discuss the unique properties of helicenes and helicene-like structures, highlighting their ability to form complex interactions with various biomolecules and their potential in the development of candidates for therapeutic agents. Recent advances in helicene derivatives with enhanced circularly polarized luminescence and other photochemical properties are also reviewed, underlining their utility in precise bio-imaging and diagnostic techniques. The review consolidates the current literature and emphasizes the growing importance of helicenes in bridging chemistry, materials science, and biology for innovative technological and biomedical applications.

Blue Light Emitting Diode Suppresses Sarcoma Cell Proliferation via the Endogenous Apoptotic Pathway Without Damaging Normal Cells

BACKGROUND

The development of novel therapies for sarcoma is urgently required because most sarcomas are refractory to adjuvant therapy and the treatment options are limited. Although antitumor effects of blue light (BL) have been reported for several malignant tumors, its impact on various sarcomas remains unknown. In this study, we examined the antitumor effects of BL on several kinds of bone and soft tissue sarcomas.

METHODS

We used human osteosarcoma, undifferentiated pleomorphic sarcoma, liposarcoma, and myxofibrosarcoma cell lines, as well as a human dermal fibroblast cell line as normal cells. We continuously irradiated these cells with BL in an incubator.

RESULTS

BL inhibited cell proliferation in sarcoma cells, but hardly affected normal cells. BL increased intracellular reactive oxygen species (ROS) levels in sarcoma cells, but not in normal cells. Interestingly, oxidative stress occurred after BL irradiation in both sarcoma and normal cells. In addition, apoptosis, autophagy, and mitochondrial dysfunction, which were induced by ROS, occurred in sarcoma cells. In undifferentiated pleomorphic sarcoma cells, BL caused cell death through activation of the endogenous apoptotic pathway, and autophagy counteracted the apoptosis.

CONCLUSION

Our results indicate that BL might specifically kill sarcoma cells without injuring normal cells and may become a new treatment option for sarcoma.

Enhanced therapeutic precision using dual drug-loaded nanomaterials for targeted cancer photodynamic therapy

Combination therapy has expanded significantly, including dual drug-loaded nanomaterials in drug delivery systems. Cancer therapy can be developed by targeting cancer cells and lessening the adverse consequences of anticancer drugs, which are just two of the numerous intriguing possibilities in this research field. Dual-drug delivery nanosystems that utilize nanotechnology to combine dual-drug administration may overcome the limitations of free drugs, the properties of nanomaterials, and the combined action of two drugs work together to overcome several drug-resistant systems within cancerous cells. It is essential to design dual-drug delivery nanosystems that use various multidrug-resistant techniques to overcome drug resistance mechanisms and enhance the effectiveness of clinical antitumor therapy. In this study, we discuss the use of photosensitizers in cancer photodynamic therapy, nanomaterials with dual-drug loading for targeted drug delivery, and the function and impact of nanomaterials in cancer photodynamic therapy. Furthermore, an overview of the drug-loaded nanomaterials in vitro and in vivo activity for cancer photodynamic treatment is discussed. The commercial and clinical applications of photosensitizer-loaded nanoparticles in cancer photodynamic therapy are also briefly discussed in the study. A key finding of the study is the importance of nanomaterials and dual drugs as effective drug delivery systems in cancer treatment.

Fungal derived dye as potential photosensitizer for antimicrobial photodynamic therapy

Photodynamic therapy (PDT) combines light with a photosensitizing agent to target and destroy abnormal cells or pathogens, offering a non-invasive and precise approach. Applying microbial dyes in PDT presents a great opportunity because these compounds may absorb specific wavelengths of light, generating reactive oxygen species (ROS) that induce oxidative stress, leading to cell or microbial death. This study evaluated the extract of Talaromyces amestolkiae containing azaphilone red dyes obtained from cultivation process as photosensitizer (PS) in antimicrobial photodynamic therapy (aPDT). Initially the crude extract was obtained in incubator shaker varying the culture media composition. Following, the crude extract containing the red dyes exhibited non-toxicity in dark conditions across all concentrations tested. PDT experiments with different amounts of the crude extract at a light dose of 80 J.cm-2 and upon irradiation at 460 nm was studied. A complete reduction of Escherichia coli and approximately 2 log10 reductions of Staphylococcus aureus, Cutibacterium acnes and Enterococcus faecalis was achieved using 25 % (v.v-1) of the crude extract while 50 % (v.v-1) of the crude extract led to a complete reduction of both E. coli and S. aureus, and around 5 log10 reductions of C. acnes and E. faecalis. Importantly, minimal photodegradation of the PS occurred during irradiation across all concentrations studied. These findings highlight the potential of T. amestolkiae-derived red dyes extract for use in aPDT, demonstrating non-toxicity in the absence of light, good aqueous solubility, high photostability, and strong microbial reduction capabilities under specific light conditions.

Advancements in Antibacterial Therapy: Feature Papers

Antimicrobial resistance (AMR) is a growing global health crisis that threatens the efficacy of antibiotics and modern medical interventions. The emergence of multidrug-resistant (MDR) pathogens, exacerbated by the misuse of antibiotics in healthcare and agriculture, underscores the urgent need for innovative solutions. (1) Background: AMR arises from complex interactions between human, animal, and environmental health, further aggravated by the overuse and inadequate regulation of antibiotics. Conventional treatments are increasingly ineffective, necessitating alternative strategies. Emerging approaches, including bacteriophage therapy, antimicrobial peptides (AMPs), nanotechnology, microbial extracellular vesicles (EVs), and CRISPR-based antimicrobials, provide novel mechanisms that complement traditional antibiotics in combating resistant pathogens. (2) Methods: This review critically analyzes advanced antibacterial strategies in conjunction with systemic reforms such as antimicrobial stewardship programs, the One Health framework, and advanced surveillance tools. These methods can enhance resistance detection, guide interventions, and promote sustainable practices. Additionally, economic, logistical, and regulatory challenges impeding their implementation are evaluated. (3) Results: Emerging technologies, such as CRISPR and nanotechnology, exhibit promising potential in targeting resistance mechanisms. However, disparities in resource distribution and regulatory barriers hinder widespread adoption. Public-private partnerships and sustainable agriculture practices are critical to overcoming these obstacles. (4) Conclusions: A holistic and integrated approach is essential for mitigating the impact of AMR. By aligning innovative therapeutic strategies with global health policies, fostering interdisciplinary collaboration, and ensuring equitable resource distribution, we can develop a sustainable response to this 21st-century challenge.

Photodynamic anti-cancer therapy and arachidonic acid metabolism: State of the art in 2024

Photodynamic therapy (PDT) has emerged as a promising and evolving modality in cancer treatment leveraging light-sensitive compounds known as photosensitizers to selectively induce cell death in malignant tissues through the generation of reactive oxygen species (ROS). This review delves into the intricate mechanisms of PDT highlighting the pivotal role of photosensitizers and the resultant oxidative stress that damages cancer cells. It explores the versatile applications of PDT across various cancer types alongside the advantages and limitations inherent to this therapy. Recent technological advancements including improved photosensitizers and novel light delivery systems are also discussed. Additionally the review examines the critical role of arachidonic acid (AA) metabolism in cancer progression detailing the cyclooxygenase, lipoxygenase and cytochrome P450 pathways and their contributions to tumor biology. By elucidating the interplay between PDT and AA metabolism the review underscores the potential of targeting AA metabolic pathways to enhance PDT efficacy. Finally it provides clinical and translational perspectives highlighting ongoing research and future directions aimed at optimizing PDT for improved cancer treatment outcomes.

Bioorthogonal reaction-mediated photosensitizer-peptide conjugate anchoring on cell membranes for enhanced photodynamic therapy

Photodynamic therapy (PDT), utilizing a photosensitizer (PS) to induce tumor cell death, is an effective modality for cancer treatment. PS-peptide conjugates have recently demonstrated remarkable antitumor potential in preclinical trials. However, the limited cell membrane binding affinity and rapid systemic clearance have hindered their transition to clinical applications. To address these challenges, we investigated whether in vivo covalent chemistry could enhance tumor accumulation and potentiate antitumor efficacy. Specifically, we synthesized a PS-peptide conjugate termed P-DBCO-Ce6, with chlorin e6 (Ce6) and dibenzocyclooctyne (DBCO) conjugated to a negatively charged short peptide. By employing metabolic glycoengineering and bioorthogonal reactions, P-DBCO-Ce6 achieves covalent bonding to the cell membrane, enabling prolonged retention of the PS on the cell surface and the in situ generation of reactive oxygen species (ROS) on cell membranes to kill tumor cells. In vivo studies demonstrated a 3.3-fold increase in tumor accumulation of the PS through bioorthogonal reactions compared to the control group, confirming that click chemistry can effectively enhance PS tumor accumulation. This approach allows for the effective elimination of tumors with a single treatment. The improved efficiency of this strategy provides new insights into the design of PDT systems for potential clinical applications.

Efficient Photosensitizer Delivery by Neutrophils for Targeted Photodynamic Therapy of Glioblastoma

Background/Objectives: Glioblastoma (GBM) is the deadliest type of brain tumor and photodynamic therapy (PDT) is a promising treatment modality of GBM. However, insufficient photosensitizer distribution in the GBM critically limits the success of PDT. To address this obstacle, we propose tumoritropic neutrophils (NE) as active carriers for photosensitizer delivery to achieve GBM-targeted PDT. Methods: Isolated mouse NE were loaded with functionalized hexagonal boron nitride nanoparticles carrying the photosensitizer chlorin e6 (BNPD-Ce6). In vitro experiments were conducted to determine drug release from the loaded NE (BNPD-Ce6@NE) to mouse GBM cells and consequential photo-cytotoxicity. In vivo experiments were performed on mice bearing intracranial graft GBMs to demonstrate GBM-targeted drug delivery and the efficacy of anti-GBM PDT mediated by BNPD-Ce6@NE. Results: BNPD-Ce6@NE displayed good viability and migration ability, and rapidly released BNPD-Ce6 to co-cultured mouse GBM cells, which then exhibited marked reactive oxygen species (ROS) generation and cytotoxicity following 808 nm laser irradiation (LI). In the in vivo study, a single intravenous bolus injection of BNPD-Ce6@NE resulted in pronounced Ce6 distribution in intracranial graft GBMs 4 h post injection, which peaked around 8 h post injection. A PDT regimen consisting of multiple intravenous BNPD-Ce6@NE injections each followed by one extracranial tumor-directed LI 8 h post injection significantly slowed the growth of intracranial graft GBMs and markedly improved the survival of host animals. Histological analysis revealed massive tumor cell damage and NE infiltration in the PDT-treated GBMs. Conclusions: NE are efficient carriers for GBM-targeted photosensitizer delivery to achieve efficacious anti-GBM PDT.

Photosensitizer associated with efflux pump inhibitors as a strategy for photodynamic therapy against bacterial resistance

Antimicrobial resistance is currently one of the biggest challenges in controlling infectious diseases and was listed among the top 10 threats to global health by the World Health Organization (WHO) in 2023. The antibiotics misuse has led to the widespread emergence of antimicrobial resistance, marking the beginning of the alarming increase in antibiotic resistance. In this context, Antimicrobial Photodynamic Therapy (aPDT) has garnered significant attention from the scientific community due to its potential to effectively eliminate multidrug-resistant pathogenic bacteria and its low propensity to induce drug resistance, which bacteria can quickly develop against traditional antibiotic treatments. However, some efflux pumps can expel diverse substrates from inside the cell, including photosensitizers used in aPDT, contributing to multidrug-resistance mechanisms. Efflux Pump Inhibitors are potential solutions to combat resistance mediated by these pumps and can play a crucial role in enhancing aPDT's effectiveness against multidrug-resistant bacteria. Therefore, combining efflux pumps inhibitors with photosensitizers can possible to eliminate the pathogen more efficiently. This review summarizes the mechanisms in which bacteria resist conventional antibiotic treatment, with a particular emphasis on efflux pump-mediated resistance, and present aPDT as a promising strategy to combat antibiotic resistance. Additionally, we highlighted several molecules of photosensitizer associated with efflux pump inhibitors as potential strategies to optimize aPDT, aiming to offer a perspective on future research directions on aPDT for overcoming the limitations of antibiotic resistance.

Mini Review On: The Roles of DNA Nanomaterials in Phototherapy

DNA-based functional nanomaterials are distinguished by their structural designability and functional controllability, making them particularly attractive in the biomedical field. Using DNA nanomaterials for cancer treatment through synergistic approaches combining photodynamic therapy and photothermal therapy has garnered significant attention. This growing interest has driven the active development of various DNA nanomaterials tailored for integrated strategies targeting cancer, including phototherapy, chemotherapy, etc. This review provides an overview of DNA nanoplatforms employed in phototherapy and synergistic therapy for cancer treatment. It highlights recent advances in DNA nanoplatforms that leverage multifaceted synergy to enhance phototherapeutic efficacy. It also offers a new perspectives and clinical application potential of DNA nanomaterials in synergistic phototherapy for malignant tumors, focusing on developments in recent years and potential directions for future research and applications.

Application of photosensitive microalgae in targeted tumor therapy

Microalgae present a novel and multifaceted approach to cancer therapy by modulating the tumor-associated microbiome (TAM) and the tumor microenvironment (TME). Through their ability to restore gut microbiota balance, reduce inflammation, and enhance immune responses, microalgae contribute to improved cancer treatment outcomes. As photosynthetic microorganisms, microalgae exhibit inherent anti-tumor, antioxidant, and immune-regulating properties, making them valuable in photodynamic therapy and tumor imaging due to their capacity to generate reactive oxygen species. Additionally, microalgae serve as effective drug delivery vehicles, leveraging their biocompatibility and unique structural properties to target the TME more precisely. Microalgae-based microrobots further expand their therapeutic potential by autonomously navigating complex biological environments, offering a promising future for precision-targeted cancer treatments. We position microalgae as a multifunctional agent capable of modulating TAM, offering novel strategies to enhance TME and improve the efficacy of cancer therapies.

Red and NIR light-triggered enhancement of anticancer and antibacterial activities of dinuclear Co(II)-catecholate complexes

Photoactive complexes of bioessential 3d metals, activable within the phototherapeutic window (650-900 nm), have gained widespread interest due to their therapeutic potential. Herein, we report the synthesis, characterization, and light-enhanced anticancer and antibacterial properties of four new dinuclear Co(II) complexes: [Co(phen)(cat)]2 (Co-1), [Co(dppz)(cat)]2 (Co-2), [Co(phen)(esc)]2 (Co-3), and [Co(dppz)(esc)]2 (Co-4). In these complexes, phen (1,10-phenanthroline) and dppz (dipyrido[3,2-a:2',3'-c]phenazine) act as neutral N,N-donor ligands, while cat2- and esc2- serve as O,O-donor catecholate ligands derived from catechol (1,2-dihydroxybenzene) and esculetin (6,7-dihydroxy coumarin). Their high-spin paramagnetic nature and dimeric identity in solution were confirmed by magnetic susceptibility, UV-visible, emission, and mass spectral data. Co-1-Co-4 exhibited an absorption band within the 600-850 nm range, originating from a charge transfer transition. The electrically neutral complexes demonstrated sufficient solution stability both in the dark and under irradiated conditions. The dppz complexes Co-2 and Co-4 exhibited notable toxicity towards A549 lung carcinoma cells, with potency increasing significantly under brief (5 min) exposure to 660 nm (red) and 808 nm (NIR) laser light (IC50 ∼ 8.9 to 14.9 μM). Notably, their toxicity towards normal NIH-3T3 fibroblast cells was minimal. Cellular assays highlighted that the induced cell death followed an apoptotic pathway, primarily due to mitochondrial damage. Co-2 and Co-4 also demonstrated significant antibacterial potency against Gram-(+) S. aureus and Gram-(-) P. aeruginosa, with effectiveness significantly enhanced upon 808 nm laser irradiation (MIC ∼ 15-142 μM). The increase in the anticancer and antibacterial efficacies was attributed to the generation of cytotoxic singlet oxygen (1O2) species upon red/NIR light exposure. Notably, 808 nm NIR irradiation produced more pronounced effects compared to 660 nm. This study is the first to report on cobalt complexes exhibiting red and NIR light-triggered enhancement of antibacterial and anticancer activities, illuminating the path for the development of long-wavelength absorbing cobalt complexes with enhanced therapeutic efficacy.

Nanoparticles improved pheophorbide-a mediated photodynamic therapy for cancer

The increased cancer incidence and mortality rates have made researchers continue to explore different types of effective and less toxic cancer therapies. Photodynamic therapy (PDT) is an alternative cancer treatment modality with reduced side effects. It is comprised of three components, a photosensitizer, molecular oxygen and light. Researchers have been exploring third generation photosensitizers that overcome existing photosensitizer limitations such as hydrophobicity, accurate targeting and photosensitivity. Pheophorbide-a is a chlorophyll product currently being explored in a number of in vitro, in vivo and in silico studies as an ideal photosensitizer for breast, prostate, lung, oral squamous cell carcinoma, gastric, osteosarcoma and cervical cancers. These in vitro, in vivo and in silico studies have shown the probable cell death pathways in different cell lines and how advancement in using nanocarriers has improved cancer cell killing effect after pheophorbide-a mediated PDT. The pharmacokinetics have elaborated on the biodistribution and tissue disposition of pheophorbide-a in this review. In summary, we offer our viewpoint on PDT in the context of cancer management, and we believe that this article will shed new light on the role of pheophorbide-a in PDT for cancer.

Construction of Photosensitizer Candidates in Photodynamic Therapy: Computer Aided Design, Calculation, and Screening

Thiophene and pyrrole units are extensively utilized in light-responsive materials and have significantly advanced the field of organic photovoltaics (OPV). This progress has inspired our exploration of photosensitizers (PS) for photodynamic therapy (PDT). Currently, traditional PS face limitations in clinical application, including a restricted variety and narrow applicability. Drawing upon molecular design concepts from OPV, we aim to transcend these limitations in PDT. Given the abundance of candidate molecules, effective screening is crucial. Theoretical calculations and electronic structure analyses serve as precise and practical screening methods. In this study, we adopted strategies successfully employed in OPV molecular design, focusing on donor-acceptor (D-A) and acceptor-donor-acceptor (A-D-A) structures. Using density functional theory (DFT) and time-dependent density functional theory (TDDFT), we systematically designed combinations of promising organic fragments. These fragments include polythiophene and polypyrrole-dominated donor structures, paired with five electron acceptors: indene (Ind), diketopyrrole (DPP), naphthalimide (Ni), benzothiazole (Btd), and dithiazolyl diketopyrrole (Tbo). Through meticulous calculations, we obtained electronic structures and spectral properties for all candidate molecules, facilitating an efficient screening process. Our findings highlight that those combinations of polypyrrole-based frameworks with DPP, Ni, and Btd show significant promise for PS applications. Approximately 13% of candidates were selected through comprehensive comparison, markedly reducing molecular design time and experimental costs. This interdisciplinary approach holds potential to pave the way for more targeted and successful PS designs.

Riboflavin-Mediated Photodynamic Therapy in Periodontology: A Systematic Review of Applications and Outcomes

Background: Riboflavin (vitamin B2) has emerged as a promising photosensitizer in photodynamic therapy (PDT) due to its strong absorption of blue light and favourable safety profile. This systematic review aims to evaluate the efficacy of riboflavin-mediated PDT in periodontology, specifically examining its antimicrobial effects and potential to improve clinical outcomes compared to conventional or other PDT-based treatments. Methods: A systematic review was conducted following PRISMA guidelines. A comprehensive literature search was performed in PubMed/Medline, Embase, Scopus, and the Cochrane Library. Studies published in English within the last 10 years were considered, where riboflavin served as the primary photosensitizer for dental treatments. Data extraction focused on study design, photosensitizer concentration, light source parameters, and clinical or microbiological outcomes. The risk of bias was assessed independently by two reviewers using a predefined scoring system. Results: Ten studies met the inclusion criteria, all demonstrating a low risk of bias. Riboflavin-mediated PDT consistently reduced microbial biofilms and pathogen viability in periodontitis, peri-implantitis, and endodontic models. Although some studies reported slightly lower efficacy compared to chlorhexidine or toluidine blue-based PDT, riboflavin-mediated PDT exhibited advantages such as minimal staining, low cytotoxicity, and enhanced collagen crosslinking. However, most studies were in vitro or small-scale clinical trials, limiting conclusions on long-term effectiveness. Conclusions: Riboflavin-mediated PDT shows promise as a safe adjunctive therapy for periodontal infections. Larger, well-designed clinical trials with standardized parameters and extended follow-up are needed to further evaluate its efficacy and optimize treatment protocols for routine clinical application.

Shift of cell-death mechanisms in primary human neutrophils with a ruthenium photosensitizer

Primary human neutrophils are the most abundant human white blood cells and are central for innate immunity. They act as early responders at inflammation sites, guided by chemotactic gradients to find infection or inflammation sites. Neutrophils can undergo both apoptosis as well as NETosis. NETosis is a form of neutrophil cell death that releases chromatin-based extracellular traps (NETs) to capture and neutralize pathogens. Understanding or controlling the balance between these cell-death mechanisms is crucial. In this study, the chemical synthesis and biologic assessment of a ruthenium complex as a light-activated photosensitizer that creates reactive oxygen species (ROS) in primary human neutrophils is reported. The ruthenium complex remains non-toxic in the dark. However, upon exposure to blue light at 450 nm, it exhibits potent cytotoxic effects in both cancerous and non-cancerous cell lines. Interestingly, the metal complex shifts the cell-death mechanism of primary human neutrophils from NETosis to apoptosis. Cells irradiated directly by the light source immediately undergo apoptosis, whereas those further away from the light source perform NETosis at a slower rate. This indicates that high ROS levels trigger apoptosis and lower ROS levels NETosis. The ability to control the type of cell death undergone in primary human neutrophils could have implications in managing acute and chronic infectious diseases.

Transition metal complexes: next-generation photosensitizers for combating Gram-positive bacteria

The rise of antibiotic-resistant Gram-positive bacterial infections poses a significant threat to public health, necessitating the exploration of alternative therapeutic strategies. A photosensitizer (PS) can convert energy from absorbed photon into reactive oxygen species (ROS) for damaging bacteria. This photoinactivation action bypassing conventional antibiotic mechanism is less prone to resistance development, making antibacterial photodynamic therapy (aPDT) highly efficient in combating Gram-positive bacteria. Photodynamic transition metal complexes leveraging the unique properties of metals to enhance the aPDT activity are the next-generation PS. This review provides an overview of metal-based PS for combating Gram-positive bacteria. Based on the structures, these metal-PS could be mainly classified as metal-tetrapyrrole derivatives, ruthenium complexes, iridium complexes, and zinc complexes. PS based on complexes of other transition metals such as silver, cobalt, and rhenium are also presented. Finally, we summarize the advantages and shortcomings of these metal- PS, conclude some critical aspects impacting their aPDT performances and give a perspective on their future development.