Recent advances of multi-dimensional porphyrin-based functional materials in photodynamic therapy

A New Insight into the Singlet Oxygen Mechanism for Photodynamic Therapy

Modern photodynamic therapy has been built on the mechanism of the interaction between the photosensitizer (porphyrin derivatives) and oxygen to produce singlet oxygen, which relies on energy transfer from the triplet excited state (T₁) of porphyrin to the excited state of oxygen. In this process, the energy transfer from the singlet excited state (S₁) of porphyrin to oxygen is believed to be not pronounced as the rapid decay of S₁ and the large energy mismatch. Here, we have evidenced the existence of an energy transfer between S₁ and oxygen, which can contribute to the production of singlet oxygen. For hematoporphyrin monomethyl ether (HMME), the Stern-Volmer constant of S₁ (K_SV') is 0.023 kPa^-1, according to the oxygen concentration-dependent steady fluorescence intensities. In addition, fluorescence dynamic curves of S₁ under various oxygen concentrations have also been measured through ultrafast pump probe experiments to further verify our results.

Research development of porphyrin-based metal-organic frameworks: targeting modalities and cancer therapeutic applications

Porphyrins are naturally occurring organic molecules that have attracted widespread attention for their potential in the field of biomedical research. Porphyrin-based metal-organic frameworks (MOFs) that utilize porphyrin molecules as organic ligands have gained attention from researchers due to their excellent results as photosensitizers in tumor photodynamic therapy (PDT). Additionally, MOFs hold significant promise and potential for other tumor therapeutic approaches due to their tunable size and pore size, excellent porosity, and ultra-high specific surface area. Active delivery of nanomaterials via targeted molecules for tumor therapy has demonstrated greater accumulation, lower drug doses, higher therapeutic efficacy, and reduced side effects relative to passive targeting through the enhanced permeation and retention effect (EPR). This paper presents a comprehensive review of the targeting methods employed by porphyrin-based MOFs in tumor targeting therapy over the past few years. It further discusses the applications of porphyrin-based MOFs for targeted cancer therapy through various therapeutic methods. The objective of this paper is to provide a valuable reference and source of ideas for targeted therapy using porphyrin-based MOF materials and to inspire further exploration of their potential in the field of cancer therapy.

Facile photosynthesis of novel porphyrin-derived nanocomposites containing Ag, Ag/Au, and Ag/Cu for photobactericidal study

In this research, the one-step synthesis of novel porphyrin-based nanocomposites was performed easily using a photochemical under visible light illumination strategy. As a result, the focus of this research is on synthesizing and using decorated ZnTPP (zinc(II)tetrakis(4-phenyl)porphyrin) nanoparticles with Ag, Ag/AgCl/Cu, and Au/Ag/AgCl nanostructures as antibacterial agents. Initially, ZnTPP NPs were synthesized as a result of the self-assembly of ZnTPP. In the next step, in a visible-light irradiation photochemically process, the self-assembled ZnTPP nanoparticles were used to make ZnTPP/Ag NCs, ZnTPP/Ag/AgCl/Cu NCs, and ZnTPP/Au/Ag/AgCl NCs. A study on the antibacterial activity of nanocomposites was carried out for Escherichia coli, and Staphylococcus aureus as pathogen microorganisms by the plate count method, well diffusion tests, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) values determination. Thereafter, the reactive oxygen species (ROS) were determined by the flow cytometry method. All the antibacterial tests and the flow cytometry ROS measurements were carried out under LED light and in dark. The (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was applied to investigate the cytotoxicity of the ZnTPP/Ag/AgCl/Cu NCs, against Human foreskin fibroblast (HFF-1) normal cells. Due to the specific properties such as admissible photosensitizing properties of porphyrin, mild reaction conditions, high antibacterial properties in the presence of LED light, crystal structure, and green synthesis, these nanocomposites were recognized as kinds of antibacterial materials that are activated in visible light, got the potential for use in a broad range of medical applications, photodynamic therapy, and water treatment.

Nanomaterials for photothermal cancer therapy

Cancer has emerged as a pressing global public health issue, and improving the effectiveness of cancer treatment remains one of the foremost challenges of modern medicine. The primary clinical methods of treating cancer, including surgery, chemotherapy and radiotherapy, inevitably result in some adverse effects on the body. However, the advent of photothermal therapy offers an alternative route for cancer treatment. Photothermal therapy relies on photothermal agents with photothermal conversion capability to eliminate tumors at high temperatures, which offers advantages of high precision and low toxicity. As nanomaterials increasingly play a pivotal role in tumor prevention and treatment, nanomaterial-based photothermal therapy has gained significant attention owing to its superior photothermal properties and tumor-killing abilities. In this review, we briefly summarize and introduce the applications of common organic photothermal conversion materials (e.g., cyanine-based nanomaterials, porphyrin-based nanomaterials, polymer-based nanomaterials, etc.) and inorganic photothermal conversion materials (e.g., noble metal nanomaterials, carbon-based nanomaterials, etc.) in tumor photothermal therapy in recent years. Finally, the problems of photothermal nanomaterials in antitumour therapy applications are discussed. It is believed that nanomaterial-based photothermal therapy will have good application prospects in tumor treatment in the future.

Transition-Metal Isocorroles as Singlet Oxygen Sensitizers

Building on a highly efficient synthesis of pyrrole-appended isocorroles, we have worked out conditions for manganese, palladium, and platinum insertion into free-base 5/10-(2-pyrrolyl)-5,10,15-tris(4-methylphenyl)isocorrole, H₂[5/10-(2-py)TpMePiC]. Platinum insertion proved exceedingly challenging but was finally accomplished with cis-Pt(PhCN)₂Cl₂. All the complexes proved weakly phosphorescent in the near-infrared under ambient conditions, with a maximum phosphorescence quantum yield of 0.1% observed for Pd[5-(2-py)TpMePiC]. The emission maximum was found to exhibit a strong metal ion dependence for the 5-regioisomeric complexes but not for the 10-regioisomers. Despite the low phosphorescence quantum yields, all the complexes were found to sensitize singlet oxygen formation with moderate to good efficiency, with singlet oxygen quantum yields ranging over 21-52%. With significant absorption in the near-infrared and good singlet oxygen-sensitizing ability, metalloisocorroles deserve examination as photosensitizers in the photodynamic therapy of cancer and other diseases.

Near-infrared absorbing semiconducting polymer nanomedicines for cancer therapy

As a new type of organic optical nanomaterials, semiconducting polymer nanoparticles (SPNs) have the advantages of good optical characteristics and photostability, low toxicity concerns, and relatively simple preparation processes. Particularly, near-infrared (NIR) absorbing SPNs have shown a great promise in biomedicine. In addition to acting as nanoprobes for molecular imaging, these SPNs can produce local heat and reactive oxygen species with the stimulation of NIR light, allowing photothermal therapy (PTT) and photodynamic therapy (PDT), respectively. Herein, we summarize the recent development of SPN-based nanomedicines for cancer therapy. The rational designs of SPNs for enhanced PTT, PDT, or combinational PTT/PDT to achieve effective ablation of tumor tissues are highlighted. Via loading/conjugating SPNs with other therapeutic elements (such as chemotherapeutic drugs and immunotherapeutic agents), phototherapy-combined chemotherapy or immunotherapy can be realized, which is then discussed. In especial, the constructions of SPN-based nanomedicines for NIR photoactivatable chemotherapy and immunotherapy are introduced with representative examples. Finally, we discuss the current challenges and key concerns of SPNs for their biomedical applications and give an outlook for their future clinical translation. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Porphyrin-Based Covalent Organic Frameworks: Design, Synthesis, Photoelectric Conversion Mechanism, and Applications

Photosynthesis occurs in high plants, and certain organisms show brilliant technology in converting solar light to chemical energy and producing carbohydrates from carbon dioxide (CO₂). Mimicking the mechanism of natural photosynthesis is receiving wide-ranging attention for the development of novel materials capable of photo-to-electric, photo-to-chemical, and photocatalytic transformations. Porphyrin, possessing a similar highly conjugated core ring structure to chlorophyll and flexible physical and chemical properties, has become one of the most investigated photosensitizers. Chemical modification and self-assembly of molecules as well as constructing porphyrin-based metal (covalent) organic frameworks are often used to improve its solar light utilization and electron transfer rate. Especially porphyrin-based covalent organic frameworks (COFs) in which porphyrin molecules are connected by covalent bonds combine the structural advantages of organic frameworks with light-capturing properties of porphyrins and exhibit great potential in light-responsive materials. Porphyrin-based COFs are expected to have high solar light utilization, fast charge separation/transfer performance, excellent structural stability, and novel steric selectivity by special molecular design. In this paper, we reviewed the research progress of porphyrin-based COFs in the design, synthesis, properties, and applications. We focused on the intrinsic relationship between the structure and properties, especially the photoelectric conversion properties and charge transfer mechanism of porphyrin-based COFs, and tried to provide more valuable information for the design of advanced photosensitizers. The applications of porphyrin-based COFs in photocatalysis and phototherapy were emphasized based on their special structure design and light-to-electric (or light-to-heat) conversion control.

Self-assembled porphyrin-based photosensitizer nanomicelles for enhanced photodynamic therapy

Preparation of a supermacromolecular photosensitizer that can stay in the tumor site and exhibits high photoconversion efficiency is useful for improving the efficacy of tumor photodynamic therapy (PDT). In this paper, we prepared tetratroxaminobenzene porphyrin (TAPP) loaded biodegradable silk nanospheres (NSs) and characterized their morphology, optical properties and the singlet oxygen-generating capacity. On this basis, the effect of in vitro photodynamic killing efficacy by as-prepared nanometer micelles was evaluated and the tumor retention ability and tumor killing effect of the nanometer micelles were verified by the co-culture of photosensitizer micelle and tumor cells. The results show that tumor cells were killed well under 660 nm laser irradiation even at a lower concentration of as-prepared TAPP NSs. In addition, due to the excellent safety of as-prepared nanomicelle, they exhibit great potential applications in improved tumor PDT.

A Novel Zinc (II) Porphyrin Is Synergistic with PEV2 Bacteriophage against Pseudomonas aeruginosa Infections

Pseudomonas aeruginosa (PsA) is an opportunistic bacterial pathogen that causes life-threatening infections in individuals with compromised immune systems and exacerbates health concerns for those with cystic fibrosis (CF). PsA rapidly develops antibiotic resistance; thus, novel therapeutics are urgently needed to effectively combat this pathogen. Previously, we have shown that a novel cationic Zinc (II) porphyrin (ZnPor) has potent bactericidal activity against planktonic and biofilm-associated PsA cells, and disassembles the biofilm matrix via interactions with eDNA In the present study, we report that ZnPor caused a significant decrease in PsA populations in mouse lungs within an in vivo model of PsA pulmonary infection. Additionally, when combined with an obligately lytic phage PEV2, ZnPor at its minimum inhibitory concentration (MIC) displayed synergy against PsA in an established in vitro lung model resulting in greater protection of H441 lung cells versus either treatment alone. Concentrations above the minimum bactericidal concentration (MBC) of ZnPor were not toxic to H441 cells; however, no synergy was observed. This dose-dependent response is likely due to ZnPor's antiviral activity, reported herein. Together, these findings show the utility of ZnPor alone, and its synergy with PEV2, which could be a tunable combination used in the treatment of antibiotic-resistant infections.

Macrocyclic Compounds: Metal Oxide Particles Nanocomposite Thin Films Deposited by MAPLE

Nanocomposite films based on macrocyclic compounds (zinc phthalocyanine (ZnPc) and 5,10,15,20-tetra(4-pyridyl) 21H,23H-porphyrin (TPyP)) and metal oxide nanoparticles (ZnO or CuO) were deposited by matrix-assisted pulsed laser evaporation (MAPLE). 1,4-dioxane was used as a solvent in the preparation of MAPLE targets that favor the deposition of films with a low roughness, which is a key feature for their integration in structures for optoelectronic applications. The influence of the addition of ZnO nanoparticles (~20 nm in size) or CuO nanoparticles (~5 nm in size) in the ZnPc:TPyP mixture and the impact of the added metal oxide amount on the properties of the obtained composite films were evaluated in comparison to a reference layer based only on an organic blend. Thus, in the case of nanocomposite films, the vibrational fingerprints of both organic compounds were identified in the infrared spectra, their specific strong absorption bands were observed in the UV-Vis spectra, and a quenching of the TPyP emission band was visible in the photoluminescence spectra. The morphological analysis evidenced agglomerated particles on the composite film surface, but their presence has no significant impact on the roughness of the MAPLE deposited layers. The current density-voltage (J-V) characteristics of the structures based on the nanocomposite films deposited by MAPLE revealed the critical role played by the layer composition and component ratio, an improvement in the electrical parameters values being achieved only for the films with a certain type and optimum amount of metal oxide nanoparticles.

Oxydextran-based photodynamic antibacterial nanoplatform with broad-Spectrum antibacterial activity

The compounding of polysaccharide macromolecules and antibacterial agents always has been the preferred strategy to prepare antibacterial products, attracting increasing interest. Herein, a novel acid-responsive oxidized dextran-based nanoplatform (OTP NP) has been fabricated for photodynamic antibacterial therapy by combing photosensitizer monoaminoporphyrin (TPP-NH₂) with oxidized dextran (ODex) via the Schiff Base reaction. OTP NP of about 100 nm is composed of an inner hydrophobic core of 30 nm and peripheral polysaccharide macromolecules. The OTP NP killed 99.9 % of E. coli and S. aureus within 1.5 light cycles at a concentration of 200 μg/mL. Concurrently, OTP NP exhibited excellent cytocompatibility at a concentration of 1 mg/mL (about 5 folds bactericidal concentration). Particularly, except for the recognized antibacterial mechanism of photodynamic therapy, a novel mechanism of bacterial membrane damage was discovered: the bacterial cell membrane was peeled off and formed spherical particles that aggregated around the bacteria to accelerate bacterial apoptosis under the combined action of ROS and nanomaterials. Moreover, the slightly soluble drug levofloxacin (Lev) as a model drug was loaded into OTP NP to test its carrier function, providing a practicable strategy to design multifunctional polysaccharide-based photodynamic antibacterial materials.

Hallmarks of anticancer and antimicrobial activities of corroles

Corroles provide a remarkable opportunity for the development of cancer theranostic agents among other porphyrinoids. While most transition metal corrole complexes are only therapeutic, post-transition metallocorroles also find their applications in bioimaging. Moreover, corroles exhibit excellent photo-physicochemical properties, which can be harnessed for antitumor and antimicrobial interventions. Nevertheless, these intriguing, yet distinct properties of corroles, have not attained sufficient momentum in cancer research. The current review provides a comprehensive summary of various cancer-relevant features of corroles ranging from their structural and photophysical properties, chelation, protein/corrole interactions, to DNA intercalation. Another aspect of the paper deals with the studies of corroles conducted in vitro and in vivo with an emphasis on medical imaging (optical and magnetic resonance), photo/sonodynamic therapies, and photodynamic inactivation. Special attention is also given to a most recent finding that shows the development of pH-responsive phosphorus corrole as a potent antitumor drug for organelle selective antitumor cytotoxicity in preclinical studies. Another biomedical application of corroles is also highlighted, signifying the application of water-soluble and completely lipophilic corroles in the photodynamic inactivation of microorganisms. We strongly believe that future studies will offer a greater possibility of utilizing advanced corroles for selective tumor targeting and antitumor cytotoxicity. In the line with future developments, an ideal pipeline is envisioned on grounds of cancer targeting nanoparticle systems upon decoration with tumor-specific ligands. Hence, we envision that a bright future lies ahead of corrole anticancer research and therapeutics.

Recent advances in engineered polymeric materials for efficient photodynamic inactivation of bacterial pathogens

Nowadays, infectious diseases persist as a global crisis by causing significant destruction to public health and the economic stability of countries worldwide. Especially bacterial infections remain a most severe concern due to the prevalence and emergence of multi-drug resistance (MDR) and limitations with existing therapeutic options. Antibacterial photodynamic therapy (APDT) is a potential therapeutic modality that involves the systematic administration of photosensitizers (PSs), light, and molecular oxygen (O₂) for coping with bacterial infections. Although the existing porphyrin and non-porphyrin PSs were effective in APDT, the poor solubility, limited efficacy against Gram-negative bacteria, and non-specific distribution hinder their clinical applications. Accordingly, to promote the efficiency of conventional PSs, various polymer-driven modification and functionalization strategies have been adopted to engineer multifunctional hybrid phototherapeutics. This review assesses recent advancements and state-of-the-art research in polymer-PSs hybrid materials developed for APDT applications. Further, the key research findings of the following aspects are considered in-depth with constructive discussions: i) PSs-integrated/functionalized polymeric composites through various molecular interactions; ii) PSs-deposited coatings on different substrates and devices to eliminate healthcare-associated infections; and iii) PSs-embedded films, scaffolds, and hydrogels for regenerative medicine applications.

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Synthetic strategies of engineered polymer-based hybrid materials integrated with photosensitizers for APDT.

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Utilization of photosensitizer-incorporated polymeric materials in health care applications.

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Challenges and opportunities in the future development of polymeric biomaterials with improved photo-bactericidal properties.

Polylactide-Meso-Substituted Arylporphyrin Composites: Structure, Properties and Antibacterial Activity

The structural features and antibacterial properties of polymer-porphyrin composites were investigated. Meso-substituted arylporphyrin 0.2-0.5 wt.% was immobilized in a polylactide matrix. The immobilization of porphyrin causes a bathochromic shift and splitting of the Soret band. This study of the morphology of the obtained composites demonstrated a uniform distribution of the meso-substituted arylporphyrin in the polylactide matrix. It was determined by the X-ray diffraction analysis that porphyrin does not affect the α-form of polylactide crystalline formations. However, its addition into the polymer somewhat reduces the melting point (by 1-2 °C) and the degree of crystallinity of polylactide (by 3-4%). The elastic characteristics of the resulting systems were determined by the ultrasonic method, and a decrease in the density of the samples with an increase of the arylporphyrin content was shown. According to the results of the biological test, the dark toxicity of the obtained composites against the microorganisms Staphylococcus aureus, Salmonella Typhimurium and Escherichia coli was shown. Immobilizates containing 0.4 and 0.5 wt.% porphyrin showed the best antibacterial effect. The antibacterial activity of the studied composites makes it possible to attribute the polylactide-porphyrin systems to promising materials in the field of medicine and bioengineering.

Supercritical CO2 Synthesis of Porous Metalloporphyrin Frameworks: Application in Photodynamic Therapy

A series of porous metalloporphyrin frameworks prepared from the 5,10,15,20-tetra(4-pyridyl)porphyrin (H₂TPyP) linker and four metal complexes, M(hfac)₂ M = Cu(II), Zn(II), Co(II), and Ni(II) (hfac: 1,1,1,5,5,5-hexafluoroacetylacetonate), were obtained using supercritical CO₂ (scCO₂) as a solvent. All the materials, named generically as [M-TPyP] _n , formed porous metal-organic frameworks (MOFs), with surface areas of ∼450 m² g^-1. All MOFs were formed through the coordination of the metal to the exocyclic pyridine moieties in the porphyrin linker. For Cu(II), Zn(II), and Co(II), incomplete metal coordination of the inner pyrrole ring throughout the structure was observed, giving place to MOFs with substitutional defects and leading to a certain level of disorder and limited crystallinity. These samples, prepared using scCO₂, were precipitated as nano- to micrometric powders. Separately, a layering technique from a mixture of organic solvents was used to crystallize high-quality crystals of the Co(II) based MOF, obtained with the formula [{Co(hfac)₂}₂H₂TPyP] _n . The crystal structure of this MOF was elucidated by single-crystal synchrotron X-ray diffraction. The Zn(II)-based MOF was selected as a potential photodynamic therapy drug in the SKBR-3 tumoral cell line showing outstanding performance. This MOF resulted to be nontoxic, but after 15 min of irradiation at 630 nm, using either 1 or 5 μM concentration of the product, almost 70% of tumor cells died after 72 h.

Recent advances in lanthanide-doped up-conversion probes for theranostics

Up-conversion (or anti-Stokes) luminescence refers to the phenomenon whereby materials emit high energy, short-wavelength light upon excitation at longer wavelengths. Lanthanide-doped up-conversion nanoparticles (Ln-UCNPs) are widely used in biomedicine due to their excellent physical and chemical properties such as high penetration depth, low damage threshold and light conversion ability. Here, the latest developments in the synthesis and application of Ln-UCNPs are reviewed. First, methods used to synthesize Ln-UCNPs are introduced, and four strategies for enhancing up-conversion luminescence are analyzed, followed by an overview of the applications in phototherapy, bioimaging and biosensing. Finally, the challenges and future prospects of Ln-UCNPs are summarized.

Mn3 O4 Nanoshell Coated Metal-Organic Frameworks with Microenvironment-Driven O2 Production and GSH Exhaustion Ability for Enhanced Chemodynamic and Photodynamic Cancer Therapies

Nanomedicine exhibits emerging potentials to deliver advanced therapeutic strategies in the fight against triple-negative breast cancer (TNBC). Nevertheless, it is still difficult to develop a precise codelivery system that integrates highly effective photosensitizers, low toxicity, and hydrophobicity. In this study, PCN-224 is selected as the carrier to enable effective cancer therapy through light-activated reactive oxygen species (ROS) formation, and the PCN-224@Mn₃ O₄ @HA is created in a simple one-step process by coating Mn₃ O₄ nanoshells on the PCN-224 template, which can then be used as an "ROS activator" to exert catalase- and glutathione peroxidase-like activities to alleviate tumor hypoxia while reducing tumor reducibility, leading to improved photodynamic therapeutic (PDT) effect of PCN-224. Meanwhile, Mn²⁺ produced cytotoxic hydroxyl radicals (∙OH) via the Fenton-like reaction, thus producing a promising spontaneous chemodynamic therapeutic (CDT) effect. Importantly, by remodeling the tumor microenvironment (TME), Mn₃ O₄ nanoshells downregulated hypoxia-inducible factor 1α expression, inhibiting tumor growth and preventing tumor revival. Thus, the developed nanoshells, via light-controlled ROS formation and multimodality imaging abilities, can effectively inhibit tumor proliferation through synergistic PDT/CDT, and prevent tumor resurgence by remodeling TME.

Inflammation specific environment activated methotrexate-loaded nanomedicine to treat rheumatoid arthritis by immune environment reconstruction

Rheumatoid arthritis (RA), as an autoimmune inflammatory disease, is featured by enhanced vascular permeability, irreversible cartilage destroys and bone erosion. Although the pathogenesis of RA is still unclear, the immune environment, particularly the lymphatic system, which is instrumental to immune cell surveillance and interstitial fluid balance, plays vital roles in the process of RA. Herein, an inflammation specific environment activated methotrexate-encapsulated nanomedicine (MTX@NPs) was constructed for RA treatment, which accumulated in inflamed joints, and released MTX in the specific RA microenvironment. Notably, MTX@NPs could regulate the immune environment including reducing the expressions of inflammatory cytokines of macrophages and the inflammatory level of lymphatic epithelial cells (LECs), and ameliorating the lymphatic vessel contraction and drainage. In vitro and In vivo studies illustrated that MTX@NPs exhibited a high RA therapeutic efficacy and insignificant systemic toxicity owing to the suppression of the inflammation response and the improved lymphatic functions of RA joints. It suggests that the nanomedicine paves a potential way to the clinical practice of autoimmune diseases treatments via the regulation of immune environment and lymphatic functions. STATEMENT OF SIGNIFICANCE: Although 1.0% of the population in the world suffers from rheumatoid arthritis (RA), the pathogenesis of RA is still unclear and the therapeutic effect of the first-line clinical drugs is relatively low. Herein, we propose a specific RA-microenvironment triggered nanomedicine (MTX@NPs), which enhances RA treatment of a first-line antirheumatic drug (methotrexate, MTX) by immune environment reconstruction. The nanomedicine exhibits RA joints accumulation by EPR effect, and releases MTX under the specific RA environment, leading to the dramatical drop of M1-type macrophages and acceleration of lymphatic vessel contraction and drainage. Finally, the inflammatory cytokines in RA immune environment are reduced sharply, indicating the outstanding therapeutic efficacy of MTX@NPs to RA.

Cyanine-Functionalized 2,2'-Bipyridine Compounds for Photocatalytic Cancer Therapy

Recently, interest has been given to developing photocatalytic anticancer drugs. This area of research is dominated by metal complexes. Here, we report the potential of lysosome/mitochondria targeting cyanine appended bipyridine compounds as the organic photocatalytic anticancer agents. The organocatalyst (bpyPCN) not only exhibits light-induced NADH oxidation but also generates intracellular ROS to demonstrate anticancer activity. This is the first example of organic compound induced catalytic NADH photo-oxidation in an aqueous solution and in cancer cells.

The Influence of Photodynamic Antimicrobial Chemotherapy on the Microbiome, Neuroendocrine and Immune System of Crustacean Post Larvae

Photodynamic antimicrobial chemotherapy (PACT), employing a combination of light and natural photosensitizer molecules such as curcumin, has been accepted as a safe modality for removing aquatic pathogens which cause diseases such as cholera in humans and vibriosis in aquatic animals. Curcumin and its photodegradation products are generally considered as safe to animals, but the impact of reactive oxygen species (ROS) generated by these products on the growth and survival of organisms at a cellular level has not been studied in detail. The ROS generated by curcumin on photoexcitation using blue light (λ_max 405 nm, 10 mW cm^-2) disinfects more than 80% of free-living Vibrio spp. in the rearing water of Penaeus monodon. However, it is less effective against Vibrio spp. colonized inside P. monodon because the carapace of the animal prevents the transmission of more than 70% of light at the 400-450 nm range and thus reduces the formation of ROS. The influence of curcumin and photoexcited curcumin on the microbiome of P. monodon were revealed by nanopore sequencing. The photoexcited curcumin induced irregular expression of genes coding the moult-inhibiting hormone (MIH), Crustacean hyperglycaemic hormone (CHH)), prophenoloxidase (ProPO), and crustin, which indicates toxic effects of ROS generated by photoexcited curcumin on the neuroendocrine and immune systems of crustaceans, which could alter their growth and survival in aquaculture settings. The study proposed the cautious use of photodynamic therapy in aquaculture systems, and care must be taken to avoid photoexcitation when animals are experiencing moulting or environmental stress.

Development of Double Hydrophilic Block Copolymer/Porphyrin Polyion Complex Micelles towards Photofunctional Nanoparticles

The electrostatic complexation between double hydrophilic block copolymers (DHBCs) and a model porphyrin was explored as a means for the development of polyion complex micelles (PICs) that can be utilized as photosensitive porphyrin-loaded nanoparticles. Specifically, we employed a poly(2-(dimethylamino) ethyl methacrylate)-b-poly[(oligo ethylene glycol) methyl ether methacrylate] (PDMAEMA-b-POEGMA) diblock copolymer, along with its quaternized polyelectrolyte copolymer counterpart (QPDMAEMA-b-POEGMA) and 5,10,15,20-tetraphenyl-21H,23H-porphine-p,p',p″,p'''-tetrasulfonic acid tetrasodium hydrate (TPPS) porphyrin. The (Q)PDMAEMA blocks enable electrostatic binding with TPPS, thus forming the micellar core, while the POEGMA blocks act as the corona of the micelles and impart solubility, biocompatibility, and stealth properties to the formed nanoparticles. Different mixing charge ratios were examined aiming to produce stable nanocarriers. The mass, size, size distribution and effective charge of the resulting nanoparticles, as well as their response to changes in their environment (i.e., pH and temperature) were investigated by dynamic and electrophoretic light scattering (DLS and ELS). Moreover, the photophysical properties of the complexed porphyrin along with further structural insight were obtained through UV-vis (200-800 nm) and fluorescence spectroscopy measurements.

Porphyrin Polymers Bearing N,N'-Ethylene Crosslinkers as Photosensitizers against Bacteria

The appearance of microbes resistant to antibiotics requires the development of alternative therapies for the treatment of infectious diseases. In this work two polymers, PTPPF₁₆-EDA and PZnTPPF₁₆-EDA, were synthesized by the nucleophilic aromatic substitution of 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin and its Zn(II) complex with ethylenediamine, respectively. In these structures, the tetrapyrrolic macrocycles were N,N'-ethylene crosslinked, which gives them greater mobility. The absorption spectra of the polymers showed a bathochromic shift of the Soret band of ~10 nm with respect to the monomers. This effect was also found in the red fluorescence emission peaks. Furthermore, both polymeric materials produced singlet molecular oxygen with high quantum yields. In addition, they were capable of generating superoxide anion radicals. Photodynamic inactivation sensitized by these polymers was tested in Staphylococcus aureus and Escherichia coli bacteria. A decrease in cell viability greater than 7 log (99.9999%) was observed in S. aureus incubated with 0.5 μM photosensitizer upon 30 min of irradiation. Under these conditions, a low inactivation of E. coli (0.5 log) was found. However, when the cells were treated with KI, the elimination of the Gram-negative bacteria was achieved. Therefore, these polymeric structures are interesting antimicrobial photosensitizing materials for the inactivation of pathogens.

Responsive Peptide Nanofibers with Theranostic and Prognostic Capacity

Photodynamic therapy (PDT) is a highly promising therapeutic modality for cancer treatment. The development of stimuli-responsive photosensitizer nanomaterials overcomes certain limitations in clinical PDT. Herein, we report the rational design of a highly sensitive PEGylated photosensitizer-peptide nanofiber (termed PHHPEG6 NF) that selectively aggregates in the acidic tumor and lysosomal microenvironment. These nanofibers exhibit acid-induced enhanced singlet oxygen generation, cellular uptake, and PDT efficacy in vitro, as well as fast tumor accumulation, long-term tumor imaging capacity and effective PDT in vivo. Moreover, based on the prolonged presence of the fluorescent signal at the tumor site, we demonstrate that PHHPEG6 NFs can also be applied for prognostic monitoring of the efficacy of PDT in vivo, which would potentially guide cancer treatment. Therefore, these multifunctional PHHPEG6 NFs allow control over the entire PDT process, from visualization of photosensitizer accumulation, via actual PDT to the assessment of the efficacy of the treatment.

'Lights, squaraines, action!' - the role of squaraine dyes in photodynamic therapy

Since they were first synthesized in 1965 by Treibs and Jacob, squaraine dyes have revolutionized the polymethine dyes' 'universe' and their potential applications due to their indisputable physical, chemical and biological properties. After 30 years and up to the present, various research teams have dedicated themselves to studying the squaraines' photodynamic therapy application using in vitro and in vivo models. The various structural modifications made to these compounds, as well as the influence they have shown to have in their phototherapeutic activity, are the main focus of the present review. Finally, the most evident limitations of this class of dyes, as well as future perspectives in the sense of hypothetically successfully overcoming them, are suggested by the authors.

Bacterial Toxin-Responsive Biomimetic Nanobubbles for Precision Photodynamic Therapy against Bacterial Infections

With few options available for the effective treatment of multidrug-resistant bacteria, photodynamic therapy (PDT) has emerged as a promising therapeutic strategy that does not promote the development of antibiotic resistance. Unfortunately, the beneficial bactericidal effect of PDT is oftentimes accompanied by the uncontrollable production of reactive oxygen species. To overcome this issue, a pore-forming toxin (PFT)-responsive biomimetic nanobubble is designed, which is constructed by co-encapsulating a perfluorocarbon nanoemulsion and a photosensitizer within the red blood cell membrane. It is shown that PFTs derived from three pathogens, including methicillin-resistant Staphylococcus aureus (MRSA), group A Streptococcus (GAS), and Listeria monocytogenes (LM), can be effectively absorbed by the nanobubble. Upon toxin absorption, the formation of pores on the nanobubble surface allows the accelerated release of oxygen dissolved inside the nanoemulsion along with the photosensitizer, thus resulting in enhanced PDT and bactericidal efficacy. In three skin infection models, treatment with the nanobubbles results in significantly decreased lesion formation and reduced inflammation. In addition to oxygen, the platform can be used to deliver nitric oxide in a bacterial toxin-dependent manner. Overall, biomimetic nanobubbles may work as a broad gas delivery system that is capable of responding to a variety of PFT-based stimuli for precision PDT.

Two cationic meso-thiophenium porphyrins and their zinc-complexes as anti-HIV-1 and antibacterial agents under non-photodynamic therapy (PDT) conditions

The anti-HIV-1 and antimicrobial activities of novel cationic meso-thiophenium porphyrins and their zinc-complex are reported under in vitro non-photodynamic (PDT) conditions. While all the cationic porphyrins led to the inhibition of de novo virus infection, the Zn(II)-complexes of T₂(OH)₂M (A₂B₂-type) and T(OH)₃M (AB₃-type) displayed potent inhibition of HIV-1 entry with T₂(OH)₂MZn displaying maximal anti-HIV activity. The Zinc complex of both the thiophenium porphyrins T₂(OH)₂M and T(OH)₃M also depicted antibacterial activities against Escherichia coli (ATCC 25922) and more prominently against Staphylococcus aureus (ATCC 25923). Again, the antibacterial activity was more potent for T₂(OH)₂MZn. Our study highlighted that the presence of two thiophenium groups at the meso-positions of the A₂B₂-type porphyrins along with zinc strongly enhanced anti-HIV and antimicrobial properties of these novel thiophenium porphyrins under non-PDT conditions.

Self-organization of zinc ions with a photosensitizer in vivo for enhanced antibiofilm and infected wound healing

Antimicrobial materials have been developed to combat bacteria more effectively and promote infected wound healing. However, it is widely recognized that the potential toxic effects and complexity of the synthesis process hinder their practical applications. In this work, we introduced a strategy for fighting bacteria and promoting wound healing caused by Staphylococcus epidermidis (S. epidermidis) infection by the self-combination of Zn²⁺ and clinically applied 5-aminolevulinic acid hydrochloride (ALA) in the microbes. The clinical ALA could target and accumulate in the biofilm as well as contribute to the low-dose Zn²⁺ penetrating the biofilm due to the self-organized formation of Zn protoporphyrin IX in situ. Upon exposing to a 635 nm laser, the self-combination of ALA and Zn²⁺ significantly inhibited and eliminated the S. epidermidis biofilm via a synergistic biofilm eradication mechanism that enhanced photodynamic inactivation and aggravated cell wall/membrane disruption. In addition, the combination of ALA and Zn²⁺ could accelerate wound repair and reduce inflammatory response without causing cytotoxicity. The proposed strategy in this study illustrates the clinical prospects of eradicating biofilms and repairing infected wounds and demonstrates good biocompatibility towards infectious diseases.

Porphyrin NanoMetal-Organic Frameworks as Cancer Theranostic Agents

Metal-Organic Frameworks (MOFs) are hybrid multifunctional platforms that have found remarkable applications in cancer treatment and diagnostics. Independently, these materials can be employed in cancer treatment as intelligent drug carriers in chemotherapy, photothermal therapy, and photodynamic therapy; conversely, MOFs can further be used as diagnostic tools in fluorescence imaging, magnetic resonance imaging, computed tomography imaging, and photoacoustic imaging. One essential property of these materials is their great ability to fine-tune their composition toward a specific application by way of a judicious choice of the starting building materials (metal nodes and organic ligands). Moreover, many advancements were made concerning the preparation of these materials, including the ability to downsize the crystallites yielding nanoporous porphyrin MOFs (NMOFs) which are of great interest for clinical treatment and diagnostic theranostic tools. The usage of porphyrins as ligands allows a high degree of multifunctionality. Historically these molecules are well known for their reactive oxygen species formation and strong fluorescence characteristics, and both have proved helpful in cancer treatment and diagnostic tools. The anticipation that porphyrins in MOFs could prompt the resulting materials to multifunctional theranostic platforms is a reality nowadays with a series of remarkable and ground-breaking reports available in the literature. This is particularly remarkable in the last five years, when the scientific community witnessed rapid development in porphyrin MOFs theranostic agents through the development of imaging technologies and treatment strategies for cancer. This manuscript reviews the most relevant recent results and achievements in this particular area of interest in MOF chemistry and application.

Glucose Oxidase Integrated Porphyrinic Covalent Organic Polymers for Combined Photodynamic/Chemodynamic/Starvation Therapy in Cancer Treatment

The anticancer effect of photodynamic therapy (PDT) is usually impeded by the hypoxia microenvironment in solid tumors; thus, it requires integration with other treatment tactics to achieve an optimal anticancer efficacy. Porphyrin-containing nanotherapeutic agents are broadly used for PDT in tumor treatment. However, chemodynamic therapy (CDT) of porphyrin-based namomaterials has been rarely reported. Here, a novel nanoscale porphyrin-containing covalent organic polymer (PCOP) was designed by the cross-linking of 5,10,15,20-tetrakis(4-aminophenyl)porphyrin with 1,1'-ferrocenedicarboxylic acid at room temperature. After glucose oxidase (GOx) was loaded, the obtained nanotherapeutic agent of PCOPs@GOx presented an augmented synergy of PDT, CDT, and energy starvation to suppress tumor growth upon near-infrared light irradiation. In vitro and in vivo outcomes demonstrated that this multifunctional nanoplatform not only realized excellent tumor inhibition but also provided a new tactic for designing chemodynamic/photodynamic/starvation combined therapy in one material.

A porphyrin-based metallacage for enhanced photodynamic therapy

In this study, we designed an effective nanoplatform to improve the photodynamic therapy (PDT) of porphyrins. Combining a porphyrin-based metallacage (PM), hyaluronidase (HAase) and DSPE-mPEG2000 together, the nanoparticle (PM@HAase-mPEG) showed enhanced PDT efficacy. The PM improved the stability of the porphyrin, avoided its aggregation and provided cavities to concentrate oxygen molecules, which was beneficial for enhancing PDT. HAase degraded HA to increase the intracellular accumulation of nanoparticles, normalized blood vessels and relieved hypoxia in tumors. PM@HAase-mPEG inhibited the growth of tumors in a 4T1 mouse model by the generated singlet oxygen with excellent PDT efficacy. This study resolved the problems of the instability of PSs, less cellular accumulation of drugs, and tumor hypoxia that limited the anti-tumor application of PDT.

Excited state and reactive oxygen species against cancer and pathogens: a review on sonodynamic and sono-photodynamic therapy

Photodynamic and sonodynamic therapy are therapies having great potential in the treatment of bacterial infections and cancer. Their background is associated with photo- and sonosensitizers - substances that can be excited when exposed to light or ultrasound. These sensitizers belong to a variety of compounds groups, including porphyrins, porphyrazines, and phthalocyanines. Releasing the energy when returning to the ground state can occur in the manner of transferring it to oxygen molecules, leading to reactive oxygen species able to disrupt membranes of bacterial and cancer cells, leaving the organism's cells unaffected. In recent years, the number of reports on numerous sensitizers being effective has been constantly growing. Therefore, the development of this field may prove beneficial for dealing with cancer and microbes. This review describes the development of photodynamic and sonodynamic therapy, as well as their combination, with emphasize on sonodynamic therapy and its potential in the treatment of cancer and bacterial infections.

Preparation of Photocatalytic and Antibacterial MOF Nanozyme Used for Infected Diabetic Wound Healing

Bacterial infection has been a considerable obstacle for diabetic wound healing. A multifunctional nanoplatform used as nanozyme for bacterial infected diabetic wound is extremely attractive. Therefore, gold nanoclusters modified zirconium-based porphyrin metal-organic frameworks (Au NCs@PCN) were constructed by an in situ growth method. Through SEM, TEM, and EDS mapping, the surface of ellipsoid-shaped particles around 190 nm was observed to be evenly interspersed with 5-8 nm gold nanoclusters. Notably, Au NCs@PCN exhibits excellent performance in exciting ROS generation and photothermal effects. Under near-infrared (NIR) laser irradiation, Au NCs@PCN can be heated to 56.2 °C and produce ROS, showing an effective killing effect on bacteria. Antibacterial studies showed that Au NCs@PCN inhibited MRSA and Amp^r E. coli by destroying membrane structure and inducing protein leakage up to 95.3% and 90.6%, respectively. Animal experiments showed that Au NCs@PCN treated diabetic rats had reduced wound coverage to 2.7% within 21 days. The immunoblot analysis showed that proangiogenic and proepithelial cell proliferation factors were expressed significantly up-regulated. These results prove that Au NCs@PCN with photocatalytic and nanozyme activity has a broad application prospect for promoting diabetic infected wound healing.

A biocompatible photosensitizer with a high intersystem crossing efficiency for precise two-photon photodynamic therapy

Photodynamic efficiency is strongly dependent on the generation rate of reactive oxygen species (ROS) and the tissue penetration depth. Recent advances in materials science reveal that organic molecules with room-temperature phosphorescence (RTP) can potentially serve as efficient photosensitizers owing to their limited dark cytotoxicity and abundant triplet excitons upon light irradiation. In this study, we combine RTP materials with two-photon excitation to improve the ROS generation, therapeutic precision, and tissue penetration of photodynamic therapy. We successfully prepared a novel RTP-based photosensitizer (BF₂DCz) with a high photoluminescence quantum yield of 47.7 ± 3% and a remarkable intersystem crossing efficiency of ∼90.3%. By encapsulation into the bovine serum albumin (BSA) matrix, BF₂DCz-BSA exhibits excellent biocompatibility, negligible dark toxicity, and superior photostability. Excitation using a femtosecond laser causes BF2DCz-BSA to efficiently generate ROS and precisely exert cell damage at the desired location.

Covalent Coupling of Porphyrins with Monolayer Graphene for Low-Voltage Synaptic Transistors

Synaptic devices emulating biological synapses are a key building component of artificial neural networks. Porphyrins and graphene, as two kinds of emerging electronic materials, have attracted extensive attention in the research of photoelectric devices due to their excellent structural and functional properties. Herein, we present a photonic synaptic transistor based on porphyrin-graphene covalent hybrids utilizing 5,10,15,20-tetrakis (4-aminophenyl)-21H,23H-porphine and monolayer graphene linked through the diazo addition reaction. The photonic synaptic device successfully simulates several essential biological functions, and the synaptic plasticity can be regulated by adjusting the parameters of light spikes and gate voltages of the device. Moreover, learning and memory behaviors under different wavelengths are studied to imitate the learning efficiency of humans in diverse emotional states. It is worth noting that all the synaptic functions can be realized at a low operating voltage of -10 mV, which is much lower than that required by most reported photonic synaptic devices. These results indicate that covalent coupling products of porphyrins with graphene have broad prospects in the construction of synaptic transistors and may arouse new research advances in neuromorphic devices with ultralow operating voltage and low energy consumption.

A carboxylatopillar[5]arene-based pH-triggering supramolecular photosensitizer for enhanced photodynamic antibacterial efficacy

A pH-triggering supramolecular antibacterial photosensitizer was constructed by host-guest interaction between a water-soluble porphyrin photosensitizer and carboxylatopillar[5]arene (P[5]). The formation of the supramolecular complex not only improves the biocompatibility of the photosensitizer, but also enhances antibacterial efficacy by pH-triggering dissociation under the low pH bacterial microenvironment.

Water-Soluble Porphyrin-Based Nanoparticles Derived from Electrostatic Interaction for Enhanced Photodynamic Therapy

Pyrrole and porphyrin-derived nanoparticles have great potential use in bioimaging and therapy because of their unique magnetic, optical, and other photophysical properties, whereas the poor solubility in aqueous solution is one of the drawbacks of current photosensitizers for their photodynamic therapy (PDT) applications. Here, we developed a kind of water-soluble porphyrin-based nanoparticles that are coassembled mainly by the electrostatic interaction of anionic porphyrins and cationic tetraphenylmethane derivative. No aggregation-caused quenching (ACQ) was detected for these nanoparticles. In addition, the simple porphyrin transformation into nanoparticles improved their ability to generate reactive oxygen species singlet oxygen (¹O₂), which is an important factor causing apoptosis. The coassembled water-soluble porphyrin-based nanoparticles exhibited enhanced antitumor efficiency via PDT both in vitro and in vivo.