In vitro photodynamic activity of lipid vesicles with zinc phthalocyanine derivative against Enterococcus faecalis

The Effect of Photodynamic Therapy on Enterococcus spp. and Its Application in Dentistry: A Scoping Review

Enterococci spp. are Gram-positive bacteria that cause mild to severe infections, many associated with the oral cavity, such as periapical infections and healthcare-associated infections (HAIs). Many of these infections become serious diseases that are difficult to resolve, specifically when multidrug-resistant (MDR) strains cause them. In recent years, the number of MDR strains of Enterococcus spp. has increased significantly. This increased prevalence of MDR strains produces significant pressure to generate more antimicrobial therapies, but there is a decline in the production of new antibiotics, driving the development of complementary therapies, such as photodynamic therapy (PDT). PDT combines a photosensitizer agent (PS), light, and oxygen to cause photooxidative stress in bacterial cells. PDT can eradicate Enterococcus spp. contaminations, improve the classic cleaning processes, and eradicate the bacteria in dental pieces. PDT's effectiveness can be improved with nanoparticles that function as carriers. Our work aims to describe the advances in PDT against Enterococcus spp. as a complement to antibiotic therapy, focusing on infections by Enterococcus faecium and Enterococcus faecalis, dental hygiene, and using nanoparticles to improve the antimicrobial effect. A systematic bibliographic search without a meta-analysis was conducted on various databases, using inclusion and exclusion criteria to identify the most relevant research. Of the 193 non-redundant articles found, 65 were selected for a systematic review, from which a summary table was created and a manual description was made. Photodynamic therapy for treating E. faecium and E. faecalis is a widely studied area, with promising results concerning bactericidal effectiveness and reductions in biofilm formation, particularly in regard to dental hygiene. Because most of the studies were conducted in vitro or ex vivo, the results indicated that there were not sufficient data to initiate clinical trials for safety and efficacy studies on humans.

Polymyxin B-targeted liposomal photosensitizer cures MDR A. baumannii burn infections and accelerates wound healing via M1/M2 macrophage polarization

Multidrug-resistant (MDR) Acinetobacter baumannii infections pose a significant challenge in burn wound management, necessitating the development of innovative therapeutic strategies. In this work, we introduced a novel polymyxin B (PMB)-targeted liposomal photosensitizer, HMME@Lipo-PMB, for precise and potent antimicrobial photodynamic therapy (aPDT) against burn infections induced by MDR A. baumanni. HMME@Lipo-PMB-mediated aPDT exhibited enhanced antibacterial efficacy by specifically targeting and disrupting bacterial cell membranes, and generating increased intracellular ROS. Remarkably, even at low concentrations, this targeted approach significantly reduced bacterial viability in vitro and completely eradicated burn infections induced by MDR A. baumannii in vivo. Additionally, HMME@Lipo-PMB-mediated aPDT facilitated burn infection wound healing by modulating M1/M2 macrophage polarization. It also effectively promoted acute inflammation in the early stage, while attenuated chronic inflammation in the later stage of wound healing. This dynamic modulation promoted the formation of granulation tissue, angiogenesis, and collagen regeneration. These findings demonstrate the tremendous potential of HMME@Lipo-PMB-mediated aPDT as a promising alternative for the treatment of burn infections caused by MDR A. baumannii.

Nanotechnology for Dentistry: Prospects and Applications

In the XXI century, application of nanostructures in oral medicine has become common. In oral medicine, using nanostructures for the treatment of dental caries constitutes a great challenge. There are extensive studies on the implementation of nanomaterials to dental composites in order to improve their properties, e.g., their adhesive strength. Moreover, nanostructures are helpful in dental implant applications as well as in maxillofacial surgery for accelerated healing, promoting osseointegration, and others. Dental personal care products are an important part of oral medicine where nanomaterials are increasingly used, e.g., toothpaste for hypersensitivity. Nowadays, nanoparticles such as macrocycles are used in different formulations for early cancer diagnosis in the oral area. Cancer of the oral cavity-human squamous carcinoma-is the sixth leading cause of death. Detection in the early stage offers the best chance at total cure. Along with diagnosis, macrocycles are used for photodynamic mechanism-based treatments, which possess many advantages, such as protecting healthy tissues and producing good cosmetic results. Application of nanostructures in medicine carries potential risks, like long-term influence of toxicity on body, which need to be studied further. The introduction and development of nanotechnologies and nanomaterials are no longer part of a hypothetical future, but an increasingly important element of today's medicine.

Zinc(II) Sulfanyltribenzoporphyrazines with Bulky Peripheral Substituents—Synthesis, Photophysical Characterization, and Potential Photocytotoxicity

The study’s aim was to synthesize new unsymmetrical sulfanyl zinc(II) porphyrazines and subject them to physicochemical and electrochemical characterization and also an initial acute toxicity assessment. The procedure was initiated from a commercially available dimercaptomaleonitrile disodium salt and o-phthalonitrile using Linstead’s macrocyclization reaction conditions, which led to magnesium(II) tribenzoporphyrazine with 4-(3,5-dibutoxycarbonylphenoxy)butylthio substituents. The obtained macrocycle was demetallated with trifluoroacetic acid and subsequently remetallated with zinc(II) acetate toward the zinc(II) porphyrazine derivative. The zinc(II) tribenzoporphyrazine with 4-(3,5-dibutoxycarbonylphenoxy)butylthio substituents was then subjected to the reduction reaction with LiAlH4, yielding zinc(II) tribenzoporphyrazine with 4-[3,5-di(hydroxymethyl)phenoxy]butylthio substituents. The new zinc(II) tribenzoporphyrazines were characterized by UV-Vis spectroscopy, various NMR techniques (1HNMR, 13CNMR, 1H-1H COSY, 1H-13C HSQC, and 1H-13C HMBC), and mass spectrometry. In the UV-Vis spectra, both macrocycles revealed characteristic Soret and Q-bands, whose positions were dependent on the solvent used for the measurements. Zinc(II) tribenzoporphyrazines were studied using electrochemical and photochemical methods, including the singlet oxygen generation assessment. Both zinc(II) porphyrazines revealed high singlet oxygen generation quantum yield values of up to 0.59 in DMSO, which indicates their potential photosensitizing potential for photodynamic therapy. In addition, new derivatives were subjected to a Microtox® bioluminescence assay.

New Metallophthalocyanines Bearing 2-Methylimidazole Moieties-Potential Photosensitizers against Staphylococcus aureus

Newly developed tetra- and octasubstituted methimazole-phthalocyanine conjugates as potential photosensitizers have been obtained. Synthesized intermediates and final products were characterized by the MALD-TOF technique and various NMR techniques, including 2D methods. Single-crystal X-ray diffraction was used to determine the crystal structures of dinitriles. The studied phthalocyanines revealed two typical absorption bands—the Soret band and the Q band. The most intense fluorescence was observed for octasubstituted magnesium(II) phthalocyanine in DMF (Φ_FL = 0.022). The best singlet oxygen generators were octasubstituted magnesium(II) and zinc(II) phthalocyanines (Φ_∆ 0.56 and 0.81, respectively). The studied compounds presented quantum yields of photodegradation at the level between 10⁻⁵ and 10⁻⁶. Due to their low solubility in a water environment, the liposomal formulations were prepared. Within the studied group, octasubstituted zinc(II) phthalocyanine at the concentration of 100 µM activated with red light showed the highest antibacterial activity against S. aureus equal to a 5.68 log reduction of bacterial growth.

Ultrasound versus Light: Exploring Photophysicochemical and Sonochemical Properties of Phthalocyanine-Based Therapeutics, Theoretical Study, and In Vitro Evaluations

Photodynamic therapy (PDT) applications carried out with the assistance of ultrasound have attracted significant attention in recent years. The use of phthalocyanines, which are an important component as photosensitizers in PDT, is becoming more important day by day. In therapeutic applications, phthalocyanines can promote the production of reactive oxygen species. Motivated by this fact, the syntheses of metal-free (2), gallium (3), and indium (4) phthalocyanines have been achieved by substituting 4-(cinnamyloxy)phthalonitrile for the first time to evaluate their therapeutic applications. Additionally, photophysicochemical, sonophotochemical, and in vitro evaluations of phthalocyanines have been reported. To the best of our knowledge, this is the first study of the use of phthalocyanines with different metal ions as potential photosensitizers for sonophotodynamic therapy (SPDT) applications in gastric cancer cell lines. The results show that the quantum yield of the generation of singlet oxygen increased in sonophotochemical studies (Φ_Δ = 0.55 (2), 0.85 (3), 0.96 (4)), compared to photochemical studies (Φ_Δ = 0.22 (2), 0.61 (3), 0.78 (4)). The density functional theory (DFT) results are in good agreement with the experimental results and suggest increased reactivity of phthalocyanines 3 and 4 in various redox processes, thus implying their applicability and usefulness as potential therapeutic agents. These phthalocyanines are effective sensitizers for PDT, sonodynamic therapy (SDT), and SPDT against MKN-28 gastric cancer cell line in vitro. All three treatments decreased cell viability and induced apoptosis in the gastric cancer cell line. However, indium phthalocyanine (4)-mediated SPDT was a more effective treatment modality compared to indium phthalocyanine (4)-mediated PDT and SDT. Also, indium phthalocyanine (4) was found to be a more effective sensitizer to activate apoptosis compared to the other phthalocyanines. To sum up, phthalocyanine-mediated SPDT enhances the cytotoxic effect on gastric cancer cells more than the effect of SDT or PDT alone.

Assessment of in vitro Cytotoxic, iNOS, Antioxidant and Photodynamic Antimicrobial Activities of Water-soluble Sulfonated Phthalocyanines

In recent years, much effort has been devoted to the development of effective anticancer agents. In this manner, the utilization of water-soluble sulfonated phthalocyanines is crucial for many cancer cell lines. In this study, phthalonitrile and metallophthalocyanine compounds linked by benzenesulfonic acid groups have been prepared. Antimicrobial behaviors of those compounds were investigated by performing disk diffusion and photodynamic assays on gram-positive and negative bacteria. Indium phthalocyanine (InClPc) (3) showed inhibition activity against B. cereus, B. subtilis and S. aureus with disk diffusion assay. Also, gallium and indium phthalocyanines (2 and 3) exhibited inhibitory activity on both gram-positive and -negative microorganisms after light activation. Increasing the inhibitor concentration and light exposure time increased the inhibition activity for both molecules. GaClPc (2) demonstrated the maximum reducing power capacity among studied compounds, and CoPc (4) showed even better DPPH radical scavenging ability than the standard molecule Trolox at 2000 µg mL^-1 concentration. The dose-dependent effect of compounds on cytotoxicity was studied against cancer cells PANC-1, MDA-MB-231, HepG2, A549, HeLa, CaCo-2 and non-tumorigenic cells HEK-293. All compounds showed no significant cytotoxic effect on any cell line up to the highest treated concentration at 50 µg mL^-1 . However, all phthalocyanines had significant nitric oxide inhibition activity, and only in copper phthalocyanine (CuPc) (5), the MTT IC₅₀ value was reached on LPS-activated RAW 264.7 macrophage cells. The lowest inducible nitric oxide synthase (iNOS) IC₅₀ values were defined as 6 ± 1 μg mL^-1 and 7 ± 0.5 μg mL^-1 for CuPc (5) and InClPc (3), respectively.

Multi-Functional Liposome: A Powerful Theranostic Nano-Platform Enhancing Photodynamic Therapy

Although photodynamic therapy (PDT) has promising advantages in almost non-invasion, low drug resistance, and low dark toxicity, it still suffers from limitations in the lipophilic nature of most photosensitizers (PSs), short half-life of PS in plasma, poor tissue penetration, and low tumor specificity. To overcome these limitations and enhance PDT, liposomes, as excellent multi-functional nano-carriers for drug delivery, have been extensively studied in multi-functional theranostics, including liposomal PS, targeted drug delivery, controllable drug release, image-guided therapy, and combined therapy. This review provides researchers with a useful reference in liposome-based drug delivery.

Symmetrically Substituted Zn and Al Phthalocyanines and Polymers for Photodynamic Therapy Application

N4 macrocyclic complexes of Al and Zn phthalocyanines with symmetrical imine and imidazole moiety at the periphery were synthesized. The synthesized ligands, complexes, and polymers were purified and characterized to study the structure of the molecule. These synthesized complexes were used for photodynamic therapy application as the diamagnetic Zn and Al have the ability to produce and stabilize singlet oxygen species. The synthesized N4 molecules of aluminum iminomethoxy phenyl phthalocyanine and aluminum ethyl phenyl benzimidazolephthalocyanine showed better activity against MCF-7 cells. These results suggest that this assay may be used as an early biomarker of clinical response.

Biologically active phthalocyanine metal complexes: Preparation, evaluation of α-glycosidase and anticholinesterase enzyme inhibition activities, and molecular docking studies

In this study, preparation, as well as investigation of α-glycosidase and cholinesterase (ChE) enzyme inhibition activities of furan-2-ylmethoxy-substituted compounds 1-7, are reported. Peripherally, tetra-substituted copper and manganese phthalocyanines (5 and 6) were synthesized for the first time. The substitution of furan-2-ylmethoxy groups provides remarkable solubility to the complex and redshift of the phthalocyanines Q-band. Besides, the inhibitory effects of these compounds on acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and α-glycosidase (α-Gly) enzymes have been investigated. The AChE was inhibited by these compounds (1-7) in low micromolar levels, and K _i values were recorded between 11.17 ± 1.03 and 83.28 ± 11.08 µM. Against the BChE, the compounds demonstrated K _i values from 7.55 ± 0.98 to 81.35 ± 12.80 µM. Also, these compounds (1-7) effectively inhibited α-glycosidase, with K _i values in the range of 744.87 ± 67.33 to 1094.38 ± 88.91 µM. For α-glycosidase, the most effective K _i values of phthalocyanines 3 and 6 were with K _i values of 744.87 ± 67.33 and 880.36 ± 56.77 µM, respectively. Moreover, the studied metal complexes were docked with target proteins PDB ID: 4PQE, 1P0I, and 3WY1. Pharmacokinetic parameters and secondary chemical interactions that play an active role in interaction were predicted with docking simulation results. Overall, furan-2-ylmethoxy-substituted phthalocyanines can be considered as potential agents for the treatment of Alzheimer's diseases and diabetes mellitus.

Photodynamic therapy with nanoparticles to combat microbial infection and resistance

Infections caused by drug-resistant pathogens are rapidly increasing in incidence and pose an urgent global health concern. New treatments are needed to address this critical situation while preventing further resistance acquired by the pathogens. One promising approach is antimicrobial photodynamic therapy (PDT), a technique that selectively damages pathogenic cells through reactive oxygen species (ROS) that have been deliberately produced by light-activated chemical reactions via a photosensitiser. There are currently some limitations to its wider deployment, including aggregation, hydrophobicity, and sub-optimal penetration capabilities of the photosensitiser, all of which decrease the production of ROS and lead to reduced therapeutic performance. In combination with nanoparticles, however, these challenges may be overcome. Their small size, functionalisable structure, and large contact surface allow a high degree of internalization by cellular membranes and tissue barriers. In this review, we first summarise the mechanism of PDT action and the interaction between nanoparticles and the cell membrane. We then introduce the categorisation of nanoparticles in PDT, acting as nanocarriers, photosensitising molecules, and transducers, in which we highlight their use against a range of bacterial and fungal pathogens. We also compare the antimicrobial efficiency of nanoparticles to unbound photosensitisers and examine the relevant safety considerations. Finally, we discuss the use of nanoparticulate drug delivery systems in clinical applications of antimicrobial PDT.

BODIPY-Based Photosensitizers as Potential Anticancer and Antibacterial Agents: Role of the Positive Charge and the Heavy Atom Effect

Boron-dipyrromethene derivatives, including cationic and iodinated analogs, were obtained and subjected to physicochemical and in vitro photodynamic activity studies. Iodinated derivatives revealed a substantial heavy atom effect manifested by a bathochromic shift of the absorption band by about 30 nm and fluorescence intensity reduced by about 30-35 times, compared to that obtained for non-iodinated ones. In consequence, singlet oxygen generation significantly increased with Φ_Δ values in the range 0.69-0.97. The in vitro photodynamic activity was evaluated on Gram-positive Staphylococcus aureus, Gram-negative Escherichia coli, and on human androgen-sensitive prostate adenocarcinoma cells (LNCaP). The novel cationic, iodinated BODIPY, demonstrated the highest activity toward all studied cells. An excellent cytotoxic effect was found against LNCaP cells with an IC₅₀ value of 19.3 nM, whereas the viability of S. aureus was reduced by >5.6 log₁₀ at 0.25 μM concentration and by >5.3 log₁₀ in the case of E. coli at 5 μM. Thus, this analog seems to be a very promising candidate for the application in both anticancer and antimicrobial photodynamic therapy.

Photosensitizing potential of tailored magnetite hybrid nanoparticles functionalized with levan and zinc (II) phthalocyanine

Phototherapies, including photodynamic therapy (PDT), have been widely used in the treatment of various diseases, especially for cancer. However, there is still a lack of effective, safe photosensitizers that would be well tolerated by patients. The combination of several methods (like phototherapy and hyperthermia) constitutes a modern therapeutic approach, which demands new materials based on components that are non-toxic without irradiation. Therefore, this study presents the synthesis and properties of novel, advanced nanomaterials in which the advantage features of the magnetic nanoparticles and photoactive compounds were combined. The primary purpose of this work was the synthesis of magnetic nanoparticles coated with biocompatible and antitumor polysaccharide - levan, previously unknown from scientific literature, and the deposition of potent photosensitizer - zinc(II) phthalocyanine on their surface. In order to better characterize the nature of the coating covering the magnetic core, the atomic force microscope analysis, a contact angle measurement, and the mechanical properties of pure levan and its blend with zinc(II) phthalocyanine films were investigated. This magnetic nanomaterial revealed the ability to generate singlet oxygen upon exposure to light. Finally, preliminary toxicity of obtained nanoparticles was tested using the Microtox® test - with and without irradiation.

Photodynamic Activity of Tribenzoporphyrazines with Bulky Periphery against Wound Bacteria

Magnesium(II) tribenzoporphyrazines with phenoxybutylsulfanyl substituents were evaluated as photosensitizers in terms of their optical properties against wound bacteria. In the UV-vis spectra of analyzed tribenzoporphyrazines, typical absorption ranges were found. However, the emission properties were very weak, with fluorescence quantum yields in the range of only 0.002–0.051. What is important, they revealed moderate abilities to form singlet oxygen with the quantum yields up to 0.27. Under irradiation, the macrocycles decomposed via photobleaching mechanism with the quantum yields up to 8.64 × 10⁻⁵. The photokilling potential of tribenzoporphyrazines was assessed against Streptococcus pyogenes, Staphylococcus epidermidis, as well as various strains of Staphylococcus aureus, including methicillin-sensitive and-resistant bacteria. Both evaluated photosensitizers revealed high photodynamic potential against studied bacteria (>3 logs). S.aureus growth was reduced by over 5.9 log, methicillin-resistant S. aureus by 5.1 log, S.epidermidis by over 5.7 log, and S. pyogenes by over 4.7 log.

Porphyrinoids in photodynamic diagnosis and therapy of oral diseases

Photodynamic methods have found application not only in the treatment process as photodynamic therapy but also for the early detection of neoplastic lesions and tumors as photodynamic diagnosis. Early detection of the disease allows not only to avoid the patient’s lifetime risk but also significantly reduce the costs of anticancer therapy, which are increasing every year. There is a constant search for new and more effective photosensitizers which will provide safety in therapy while maintaining efficiency. This paper summarizes recent reports focused on the photodynamic diagnosis of oral cancers. Moreover, it shows methods of the photodynamic treatment of oral verrucous hyperplasia, erythroleukoplakia, and oral leukoplakia. The treatment of choice for these diseases is a surgical excision, which always leads to scar formation. Photodynamic therapy provides a new scar-less tool for the treatment.