Developments in PDT Sensitizers for Increased Selectivity and Singlet Oxygen Production

Organelle-targeted small molecular photosensitizers for enhanced photodynamic therapy: a minireview for recent advances and potential applications

Photodynamic therapy (PDT) is a promising approach for cancer treatment that involves the use of photosensitizers to generate reactive oxygen species upon light irradiation, resulting in selective cytotoxicity. To enhance the efficiency of PDT, researchers have developed organelle-targeting photosensitizers that specifically accumulate in critical cellular organelles. This review provides a comprehensive overview of recent advancements in the development of organelle-targeting photosensitizers for PDT. Different organelles, including mitochondria, plasma membrane, lysosome, endoplasmic reticulum, lipid droplets, nucleus, and Golgi, have been targeted to improve the selectivity and effectiveness of PDT. Various strategies have been employed to design and synthesize these photosensitizers, optimizing their organelle-specific accumulation and photodynamic efficiency. This review discusses the principles and mechanisms underlying the design of organelle-targeting photosensitizers, along with their exceptional results achieved in preclinical studies. Furthermore, potential applications and challenges in the development of multi-organelles-targeting photosensitizers and the synergistic use of multiple photosensitizers targeting different organelles are highlighted. Overall, organelle-targeting photosensitizers offer a promising avenue for advancing the field of PDT and improving its clinical applicability.

Smart SPIONs for Multimodal Cancer Theranostics: A Review

Despite significant advancements in anticancer research, the performance statistics of current therapeutic regimens yield unsatisfactory outcomes. Issues such as high metastasis rates, drug resistance, limited efficacy, and severe side effects underscore the urgent need for safer and more effective strategies for tumor mitigation. One promising approach lies in the use of superparamagnetic iron oxide nanoparticles (SPIONs) for hybridized cancer therapy, leveraging their unique properties and functional versatility to enhance treatment efficacy and safety. They can serve as platforms for various therapeutic as well as diagnostic applications, enhancing imaging techniques such as magnetic resonance imaging. This paper presents an in-depth compilation of the application of nanoparticulate SPIONs amalgamates for multimodal cancer therapeutics. Physical phenomena such as light, heat, sound, and magnetism can be coupled to nanoparticulate delivery systems for developing targeted, precision medicine against cancer. Integration of noninvasive and effective platforms technologies such as photodynamic therapy, photothermal therapy, magnetic hyperthermia, and sonodynamic therapy hold great promise in counteracting the daunting challenges within cancer therapeutics.

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.

Bismuth doped carbon nanospheres conjugated to boronated porphyrins for photodynamic therapy

Novel 4- (5,10,15)-tris-boronphenyl-20-(4-formylphenoxy) porphyrin (complex 1) and its Zn-metalated derivative (complex 2) were synthesized and conjugated to bismuth doped carbon nanospheres (BiCNS) through non-covalent bonds (π-π). The conjugation of BiCNS to porphyrin complexes enhanced the singlet oxygen production of porphyrin complexes, as it was observed that porphyrin complex 1 gave a singlet oxygen quantum yield (Φ∆) value of 0.17 and complex 2 gave Φ∆ of 0.23, and upon conjugation with BiCNS the Ф∆ values increased to 0.52 and 0.67, respectively. Photodynamic therapy (PDT) studies were performed against MDA-MB-231 breast cancer cell line using these complexes and their conjugates and it was observed that BiCNS conjugates resulted in enhanced PDT activity when compared to CNS conjugates. Conjugates 2-CNS, and 2-BiCNS at the concentration of 100 µg/mL they resulted with cell viabilities of 28.43 and 26.82 %, respectively.

An esophageal stent integrated with wireless battery-free movable photodynamic-therapy unit for targeted tumor treatment

Esophageal cancer is the eighth most common cancer worldwide and the sixth leading cause of cancer-related deaths. In this study, we propose a novel esophageal stent equipped with a wireless, battery-free, and movable photodynamic therapy (PDT) unit designed to treat esophageal tumors with flexibility, precision, and real-time control. This system integrates a PDT unit and an electrochemical pneumatic soft actuator into a conventional esophageal stent. Each module incorporates a piezoelectric transducer capable of receiving external ultrasound to power the respective module. These transducers selectively respond to different external ultrasound frequencies, enabling independent operation without mutual interference. The therapy module provides a light source for PDT, inducing the production of cytotoxic reactive oxygen species (ROS) in tumor cells and promoting apoptosis. The pneumatic actuator based on electrochemical principles plays a critical role in controlling the position of the PDT light source, enabling the movement of the therapy module up to 200 mm within 15 min. This allows real-time control to maintain the light source near the tumor, ensuring precise and targeted treatment. The system can wirelessly and in real-time control the PDT light source's position via external ultrasound, offering a novel approach for treating esophageal cancer patients according to the need of tumor's progression.

Impact of the hydrophilic-lipophilic balance of free-base and Zn(II) tricationic pyridiniumporphyrins and irradiation wavelength in PDT against the melanoma cell lines

The amphiphilic and asymmetric structure of porphyrins, when used as photosensitizers (PSs) for photodynamic therapy (PDT), has been shown through numerous previous studies to be a very important property that facilitates their entry into cells, which improves their efficiency in PDT. In this work, two groups of cationic AB3 pyridiniumporphyrins, free-base and chelated with Zn(II), both substituted with alkyl chains of various lengths, were studied in PDT on melanoma cell lines. The aim was to investigate the impact of hydrophilic-lipophilic balance and Zn(II) chelation, and the importance of matching the irradiation wavelength to the optical properties of the PS on in vitro PDT efficiency. Therefore, spectroscopic studies, singlet oxygen production and lipophilicity as well as cellular uptake, localization and cytotoxicity studies of the two series of porphyrins were performed. In both series of porphyrins, the longest alkyl chain (17 C-atoms long) enables the greatest internalization of the PS. Chelation with Zn(II) resulted in better physicochemical properties, but slower cellular internalization. As expected, free-base porphyrins were more PDT efficient than their Zn(II) complexes after 30-min photoactivation by low-fluence (2 mW/cm2) red light (643 nm). However the use of orange light (606 nm) with the same fluence rate was more suitable for Zn(II) porphyrins and resulted in similar overall toxicity to their free-base analogues with similar lipophilicity. Although the highest phototoxicity was achieved with the PSs carrying the longest alkyl chain, TMPyP3-C13H27 and Zn(II)-TMPyP3-C13H27 proved to be the most promising candidates for use in PDT as they exhibit high phototoxicity, but also greater selectivity towards melanoma cell lines (MeWo and A375) compared to fibroblasts (HDF).

Theranostic dye entrapped in an optimized blended-polymer matrix for effective photodynamic inactivation of diseased cells

Despite the wide range of treatment options available for cancer therapy, including chemotherapy, radiation therapy, and surgical procedures, each of these treatments has a different side-effect profile and leaves the patient with no option but to choose. Due to their insensitivity and nonspecificity, conventional treatments damage normal cells together with cancer cells. In recent years, a significant amount of attention has been focused on photodynamic therapy (PDT) as a treatment for cancer and drug-resistant microbes. An activated photosensitizer is used as a part of the procedure along with oxygen molecules and a specific wavelength of light belonging to the visible or NIR spectral zone. A light-sensitive laser dye, rhodamine 6G (R6G), was used in the present study as a photosensitizer, taking a challenge to improve the aqueous solubility and ROS quantum yield using optimum concentration (160 mg/ml) of chitosan-alginate (Cs-Alg) blended polymeric nanoformulations. As evidenced by steady-state spectrophotometric and fluorometric measurements, ROS quantum yield increases three-fold over aqueous solution along with solubility gaining that was validated by PDT experiment using human epithelial carcinoma (KB) cell line. Phantom optical imaging was taken using the IVIS imaging system to establish the formulations as a fluorescence-based optical contrast agent, and zebrafish embryos were used to establish their safe in vivo use. The release profile of R6G was fitted using kinetic models, which followed the Non-Fickian kinetic profile. In conclusion, we recommend the formulations as a potential theranostic agent that will aid in PDT-based therapy in conjunction with optical imaging-based diagnosis.

Recent Advances in Thermally Activated Delayed Fluorescent Materials in Type II Photodynamic Therapy

Photodynamic therapy (PDT) represents a novel, dual-stage cancer treatment approach that combines light energy and photosensitizers to destroy cancerous and precancerous cells through the generation of radicals (Type I) or singlet oxygen (Type II). Since the early 2010s, PDT has advanced significantly, with the focus shifting toward the exploration of molecules capable of thermally activated delayed fluorescence (TADF) as viable alternatives to traditional metallic complexes and organometallic compounds for producing the necessary active species. TADF molecules exhibit higher energy conversion efficiency, long-lived triplet excitons, tunable photophysical properties, and a small singlet-triplet energy gap, facilitating efficient intersystem crossing and enhanced singlet oxygen generation. As metal-free luminophores, they offer benefits such as reduced health risks, high structural flexibility, and biocompatibility, which can significantly enhance PDT treatment efficacy. Notably, in 2019, a pivotal shift occurred, with researchers concentrating their efforts on identifying and investing in potential molecules specifically for Type II PDT applications. This review presents the innovative use of materials characterized by closely spaced S1 and T1 orbitals, crucial for the efficient generation of singlet oxygen in PDT. Exploring these materials opens new avenues for enhancing the efficacy and specificity of PDT, offering promising for future cancer treatments.

Advances in nanotechnology-assisted photodynamic therapy for neurological disorders: a comprehensive review

Neurological disorders such as neurodegenerative diseases and nervous system tumours affect more than one billion people throughout the globe. The physiological sensitivity of the nervous tissue limits the application of invasive therapies and leads to poor treatment and prognosis. One promising solution that has generated attention is Photodynamic therapy (PDT), which can potentially revolutionise the treatment landscape for neurological disorders. PDT attracted substantial recognition for anticancer efficacy and drug conjugation for targeted drug delivery. This review thoroughly explained the basic principles of PDT, scientific interventions and advances in PDT, and their complicated mechanism in treating brain-related pathologies. Furthermore, the merits and demerits of PDT in the context of neurological disorders offer a well-rounded perspective on its feasibility and challenges. In conclusion, this review encapsulates the significant potential of PDT in transforming the treatment landscape for neurological disorders, emphasising its role as a non-invasive, targeted therapeutic approach with multifaceted applications.

Co-Delivery of VEGF siRNA and THPP via Metal-Organic Framework Reverses Cisplatin-Resistant Non-Small Cell Lung Cancer and Inhibits Metastasis through a MUC4 Regulating Mechanism

Cisplatin resistance significantly impacts the antitumor efficacy of cisplatin chemotherapy and contributes to poor prognosis, including metastasis. In this study, we present the utilization of metal-organic framework (MOF) nanoparticles as the therapeutic component and drug loading scaffold for implementing a ternary combination therapeutic strategy to combat cisplatin-resistant lung cancer and metastasis. Specifically, by engineering MOFs (Cis@MOF-siVEGF) through the self-assembly of THPP as photosensitizer for photodynamic therapy (PDT), along with the incorporation of cisplatin (DDP) and VEGF siRNA (siVEGF), we propose the leverage of photodynamic-induced oxidative damage and gene silencing of the angiogenic factor to reverse cisplatin resistance and sensitize therapeutic potency. Our findings demonstrated that the chemo/photodynamic/antiangiogenic triple combination therapy via Cis@MOF-siVEGF under irradiation effectively inhibits cisplatin-resistant tumor growth and induces abscopal effects. Importantly, molecular mechanistic exploration suggested that MUC4 exerted regulatory effects on governing cancer metastasis, thus representing a potential immunotherapeutic target for cancer intervention. Overall, our study creates a MOFs-based multicomponent delivery platform for complementary therapeutic modules with synergistically enhanced antitumor efficacy and sheds light on potential regulatory mechanisms on cisplatin-resistance cancers.

Photodynamic Therapy: Past, Current, and Future

The Greek roots of the word "photodynamic" are as follows: "phos" (φω~ς) means "light" and "dynamis" (δύναμις) means "force" or "power". Photodynamic therapy (PDT) is an innovative treatment method based on the ability of photosensitizers to produce reactive oxygen species after the exposure to light that corresponds to an absorbance wavelength of the photosensitizer, either in the visible or near-infrared range. This process results in damage to pathological cancer cells, while minimizing the impact on healthy tissues. PDT is a promising direction in the treatment of many diseases, with particular emphasis on the fight against cancer and other diseases associated with excessive cell growth. The power of light contributed to the creation of phototherapy, whose history dates back to ancient times. It was then noticed that some substances exposed to the sun have a negative effect on the body, while others have a therapeutic effect. This work provides a detailed review of photodynamic therapy, from its origins to the present day. It is surprising how a seemingly simple beam of light can have such a powerful healing effect, which is used not only in dermatology, but also in oncology, surgery, microbiology, virology, and even dentistry. However, despite promising results, photodynamic therapy still faces many challenges. Moreover, photodynamic therapy requires further research and improvement.

Two in one: merging photoactivated chemotherapy and photodynamic therapy to fight cancer

The growing number of cancer cases requires the development of new approaches for treatment. A therapy that has attracted the special attention of scientists is photodynamic therapy (PDT) due to its spatial and temporal resolution. However, it is accepted that this treatment methodology has limited application in cases of low cellular oxygenation, which is typical of cancerous tissues. Therefore, a strategy to overcome this drawback has been to combine this therapy with photoactivated chemotherapy (PACT), which works independently of the presence of oxygen. In this perspective, we examine compounds that act as both PDT and PACT agents and summarize their photophysical and biological characteristics.

Singlet Oxygen Photophysics: From Liquid Solvents to Mammalian Cells

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

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

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

Advances in Medicine: Photodynamic Therapy

Over the past decades, medicine has made enormous progress, revolutionized by modern technologies and innovative therapeutic approaches. One of the most exciting branches of these developments is photodynamic therapy (PDT). Using a combination of light of a specific wavelength and specially designed photosensitizing substances, PDT offers new perspectives in the fight against cancer, bacterial infections, and other diseases that are resistant to traditional treatment methods. In today's world, where there is a growing problem of drug resistance, the search for alternative therapies is becoming more and more urgent. Imagine that we could destroy cancer cells or bacteria using light, without the need to use strong chemicals or antibiotics. This is what PDT promises. By activating photosensitizers using appropriately adjusted light, this therapy can induce the death of cancer or bacterial cells while minimizing damage to surrounding healthy tissues. In this work, we will explore this fascinating method, discovering its mechanisms of action, clinical applications, and development prospects. We will also analyze the latest research and patient testimonies to understand the potential of PDT for the future of medicine.

Recent breakthroughs in graphene quantum dot-enhanced sonodynamic and photodynamic therapy

Water-soluble graphene quantum dots (GQDs) have recently exhibited considerable potential for diverse biomedical applications owing to their exceptional optical and chemical properties. However, the pronounced heterogeneity in the composition, size, and morphology of GQDs poses challenges for a comprehensive understanding of the intricate correlation between their structural attributes and functional properties. This variability also introduces complexities in scaling the production processes and addressing safety considerations. Light and sound have firmly established their role in clinical applications as pivotal energy sources for minimally invasive therapeutic interventions. Given the limited penetration depth of light, photodynamic therapy (PDT) predominantly targets superficial conditions such as dermatological disorders, head and neck malignancies, ocular ailments, and early-stage esophageal cancer. Conversely, ultrasound-based sonodynamic therapy (SDT) capitalizes on its superior ability to propagate and focus ultrasound within biological tissues, enabling a diverse range of therapeutic applications, including the management of gliomas, breast cancer, hematological tumors, and modulation of the blood-brain barrier (BBB). Considering the advancements in theranostic and precision therapies, reevaluating these conventional energy sources and their associated sensitizers is imperative. This review introduces three prevalent treatment modalities that harness light and sound stimuli: PDT, SDT, and a synergistic approach that integrates PDT and SDT. This study delineated the therapeutic dynamics and contemporary designs of sensitizers tailored to these modalities. By exploring the historical context of the field and elucidating the latest design strategies, this review underscores the pivotal role of GQDs in propelling the evolution of PDT and SDT. This aspires to stimulate researchers to develop "multimodal" therapies integrating both light and sound stimuli.

Isolation, Identification, and Biological Activities of a New Chlorin e6 Derivative

Chlorin e6 is a well-known photosensitizer used in photodynamic diagnosis and therapy. A method for identifying and purifying a novel process-related impurity during the synthesis of chlorin e6 has been developed. Its structure was elucidated using NMR and HRMS. This new impurity is formed from chlorophyll b rather than chlorophyll a, which is the source of chlorin e6. The intermediates formed during chlorin e6 synthesis were monitored using HPLC-mass spectrometry. This new impurity was identified as rhodin g7 71-ethyl ester, the structure of which remains unknown to date. The cytotoxic effects of this novel compound in both dark and light conditions were studied against five cancer cell lines (HT29, MIA-PaCa-2, PANC-1, AsPC-1, and B16F10) and a normal cell line (RAW264.7) and compared to those of chlorin e6. Upon irradiation using a laser at 0.5 J/cm2, rhodin g7 71-ethyl ester demonstrated higher cytotoxicity (2-fold) compared to chlorin e6 in the majority of the cancer cell lines. Furthermore, this new compound exhibited higher dark cytotoxicity compared to chlorin e6. Studies on singlet oxygen generation, the accumulation in highly vascular liver tissue, and the production of reactive oxygen species in MIA-PaCa-2 cancer cells via rhodin g7 71-ethyl ester correspond to its higher cytotoxicity as a newly developed photosensitizer. Therefore, rhodin g7 71-ethyl ester could be employed as an alternative or complementary agent to chlorin e6 in the photodynamic therapy for treating cancer cells.

Ir(III) Half-Sandwich Photosensitizers with a π-Expansive Ligand for Efficient Anticancer Photodynamic Therapy

One approach to reduce the side effects of chemotherapy in cancer treatment is photodynamic therapy (PDT), which allows spatiotemporal control of the cytotoxicity. We have used the strategy of coordinating π-expansive ligands to increase the excited state lifetimes of Ir(III) half-sandwich complexes in order to facilitate the generation of 1O2. We have obtained derivatives of formulas [Cp*Ir(C∧N)Cl] and [Cp*Ir(C∧N)L]BF4 with different degrees of π-expansion in the C∧N ligands. Complexes with the more π-expansive ligand are very effective photosensitizers with phototoxic indexes PI > 2000. Furthermore, PI values of 63 were achieved with red light. Time-dependent density functional theory (TD-DFT) calculations nicely explain the effect of the π-expansion. The complexes produce reactive oxygen species (ROS) at the cellular level, causing mitochondrial membrane depolarization, cleavage of DNA, nicotinamide adenine dinucleotide (NADH) oxidation, as well as lysosomal damage. Consequently, cell death by apoptosis and secondary necrosis is activated. Thus, we describe the first class of half-sandwich iridium cyclometalated complexes active in PDT.

In vitro evaluation of the efficacy of photodynamic therapy using 5-ALA on homologous feline mammary tumors in 2D and 3D culture conditions and a mouse subcutaneous model with 3D cultured cells

BACKGROUND

Numerous studies have shown that photodynamic therapy (PDT) has a therapeutic effect on mammary tumor cells, with 5-aminolevulinic acid (5-ALA-HCL) being a commonly used photosensitizer for PDT. Feline mammary tumors (FMTs) are relatively common. However, the cytotoxic and antitumor effects of 5-ALA-PDT on FMTs have not been clarified. To this end, we evaluated the therapeutic effect of 5-ALA-PDT on FMTs through in vitro experiments using an FMT FKR cell line established for this study.

METHODS

We performed 5-ALA-PDT in 2D-cultured FKR-A (adherent cells) and 3D-cultured FKR-S (spheroid cells) cells and performed a series of studies to evaluate the cell viability and determine the protoporphyrin IX (PpIX) content in the cells as well as the expression levels of mRNAs associated with PpIX production and release. An in vivo study was performed to assess the effectiveness of 5-ALA-PDT.

RESULTS

There was a significant difference in the concentration of PpIX in FMT cells under different incubation culture modes (2D versus 3D culture). The concentration of PpIX in FMT cells was correlated with the differences in cell culture (2D and 3D) as well as the expression levels of genes such as PEPT1, PEPT2, FECH, and HO-1.

CONCLUSIONS

In the in vitro study, 5-ALA-PDT had a stronger inhibitory effect on 3D-cultured FKR-S cells, which resemble the internal environment of organisms more closely. We also observed a significant inhibitory effect of 5-ALA-PDT on FMT cells in vivo. To our knowledge, this is the first study on 5-ALA-PDT for FMTs under both 2D and 3D conditions.

Nano-phototherapy: Favorable prospects for cancer treatment

Nanotechnology-based phototherapies have drawn interest in the fight against cancer because of its noninvasiveness, high flexibility, and precision in terms of cancer targeting and drug delivery based on its surface properties and size. Phototherapy has made remarkable development in recent decades. Approaches to phototherapy, which utilize nanomaterials or nanotechnology have emerged to contribute to advances around nanotechnologies in medicine, particularly for cancers. A brief overviews of the development of photodynamic therapy as well as its mechanism in cancer treatment is provided. We emphasize the design of novel nanoparticles utilized in photodynamic therapy while summarizing the representative progress during the recent years. Finally, to forecast important future research in this area, we examine the viability and promise of photodynamic therapy systems based on nanoparticles in clinical anticancer treatment applications and briefly make mention of the elimination of all reactive metabolites pertaining to nano formulations inside living organisms providing insight into clinical mechanistic processes. Future developments and therapeutic prospects for photodynamic treatments are anticipated. Our viewpoints might encourage scientists to create more potent phototherapy-based cancer therapeutic modalities. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Kinetic effects in singlet oxygen mediated oxidations by immobilized photosensitizers on silica

Singlet oxygen (1O2) mediated photo-oxidations are important reactions involved in numerous processes in chemical and biological sciences. While most of the current research works have aimed at improving the efficiencies of these transformations either by increasing 1O2 quantum yields or by enhancing its lifetime, we establish herein that immobilization of a molecular photosensitizer onto silica surfaces affords significant, substrate dependant, enhancement in the reactivity of 1O2. Probing a classical model reaction (oxidation of Anthracene-9, 10-dipropionic acid, ADPA or dimethylanthracene, DMA) with various spectrofluorimetric techniques, it is here proposed that an interaction between polar substrates and the silica surface is responsible for the observed phenomenon. This discovery could have a direct impact on the design of future photosensitized 1O2 processes in various applications ranging from organic photochemistry to photobiology.

Photodynamic inactivation by hypericin-P123 on azole-resistant isolates of the Trichophyton rubrum complex as planktonic cells and biofilm

INTRODUCTION

The Trichophyton rubrum complex comprises the majority of dermatophyte fungi (DM) responsible for chronic cases of onychomycosis, which is treated with oral or topical antifungals. However, owing to antifungal resistance, alternative therapies, such as photodynamic therapy (PDT), are needed. This study investigated the frequency of the T. rubrum species complex in onychomycosis cases in the northwestern region of Paraná state, Brazil, and evaluated the efficacy of (PDT) using P123-encapsulated hypericin (Hyp-P123) on clinical isolates of T. rubrum in the planktonic cell and biofilm forms.

MATERIAL AND METHODS

The frequency of the T. rubrum complex in onychomycosis cases from 2017 to 2021 was evaluated through a data survey of records from the Laboratory of Medical Mycology (LEPAC) of the State University of Maringa (UEM). To determine the effect of PDT-Hyp-P123 on planktonic cells of T. rubrum isolates, 1 × 105 conidia/mL were treated with ten different concentrations of Hyp-P123 and then irradiated with 37.8 J/cm2. Antibiofilm activity of PDT-Hyp-P123 was tested against T. rubrum biofilm in the adhesion phase (3 h), evaluated 72 h after irradiation (37.8 J/cm2), and the mature biofilm (72 h), evaluated immediately after irradiation. In this context, three different parameters were evaluated: cell viability, metabolic activity and total biomass.

RESULTS

The T. rubrum species complex was the most frequently isolated DM in onychomycosis cases (approximately 80 %). A significant reduction in fungal growth was observed for 75 % of the clinical isolates tested with a concentration from 0.19 μmol/L Hyp-P123, and 56.25 % had complete inhibition of fungal growth (fungicidal action); while all isolates were azole-resistant. The biofilm of T. rubrum isolates (TR0022 and TR0870) was inactivated in both the adhesion phase and the mature biofilm.

CONCLUSION

PDT-Hyp-P123 had antifungal and antibiofilm activity on T. rubrum, which is an important dermatophyte responsible for onychomycosis cases.

A Uniform Design Method Can Optimize the Combinatorial Parameters of Antimicrobial Photodynamic Therapy, Including the Concentrations of Methylene Blue and Potassium Iodide, Light Dose, and Methylene Blue's Incubation Time, to Improve Fungicidal Effects on Candida Species

The optimal combinatorial parameters of antimicrobial photodynamic therapy (aPDT) mediated by methylene blue (MB) with the addition of potassium iodide (KI) against Candida species have never been defined. This study aimed to optimize the combinatorial parameters of aPDT, including the concentrations of MB (X1, 0.1-1.0 mM) and KI (X2, 100-400 mM), light dose (X3, 10-70 J/cm2), and MB's incubation time (X4, 5-35 min) for three Candida species. The best MB + KI-aPDT fungicidal effects (Y) against Candida albicans ATCC 90028 (YCa), Candida parapsilosis ATCC 22019 (YCp), and Candida glabrata ATCC 2950 (YCg) were investigated using a uniform design method. The regression models deduced using this method were YCa = 7.126 + 1.199X1X3 - 1.742X12 + 0.206X22 - 0.361X32; YCp = 10.724 - 0.867X1 - 1.497X2 + 0.560X3 + 1.298X22; and YCg = 0.892 - 0.956X1 + 2.296X3 + 1.299X42 - 3.316X3X4. The optimal combinatorial parameters inferred from the regression equations were MB 0.1 mM, KI 400 mM, a light dose of 20 J/cm2, and a 5-minute incubation time of MB for Candida albicans; MB 0.1 mM, KI 400 mM, a light dose of 70 J/cm2, and a 5-minute incubation time of MB for Candida parapsilosis; MB 0.1 mM, KI 100 mM, a light dose of 10 J/cm2, and a 35-minute incubation time of MB for Candida glabrata. The uniform design method can optimize the combinatorial parameters of aPDT mediated by MB plus KI to obtain the best aPDT fungicidal effects on Candida species, providing a new method to optimize the combinatorial parameters of aPDT for different pathogens in the future.

TFOS Lifestyle: Impact of cosmetics on the ocular surface

In this report the use of eye cosmetic products and procedures and how this represents a lifestyle challenge that may exacerbate or promote the development of ocular surface and adnexal disease is discussed. Multiple aspects of eye cosmetics are addressed, including their history and market value, psychological and social impacts, possible problems associated with cosmetic ingredients, products, and procedures, and regulations for eye cosmetic use. In addition, a systematic review that critically appraises randomized controlled trial evidence concerning the ocular effects of eyelash growth products is included. The findings of this systematic review highlight the evidence gaps and indicate future directions for research to focus on ocular surface outcomes associated with eyelash growth products.

Spotlight on porphyrins: Classifications, mechanisms and medical applications

Photodynamic therapy (PDT) and sonodynamic therapy (SDT) are non-invasive treatment methods with obvious inhibitory effect on tumors and have few side effects, which have been widely concerned and explored by researchers. Sensitizer is the main factor in determining the therapeutic effect of PDT and SDT. Porphyrins, a group of organic compounds widespread in nature, can be activated by light or ultrasound and produce reactive oxygen species. Therefore, porphyrins as sensitizers in PDT have been widely explored and investigated for many years. Herein, we summarize the classical porphyrin compounds and their applications and mechanisms in PDT and SDT. The application of porphyrin in clinical diagnosis and imaging is also discussed. In conclusion, porphyrins have good application prospects in disease treatment as an important part of PDT or SDT, and in clinical diagnosis and imaging.

"Domino" cascade reactor based on DNA hydrogel for synergistic treatment of malignant tumor

The action pathways of starvation therapy and photodynamic therapy (PDT) do not exist in isolation and are usually related to tumor cell metabolism and immune regulation, which are of great significance in the treatment of malignant tumors. Here, a cancer-targeted "domino" cascade reactor is constructed for synergistic starvation therapy and amplifies photodynamic therapy by assembling hemin and glucose oxidase (GOx) into DNA hydrogel load with hypoxia-inducible factor 1α (HIF-1α) and photosensitizer chlorin e6 (Ce6). The cascade reactor has excellent biocompatibility and tumor targeting, which promotes PDT by reducing HIF-1α. At the same time, the G-quadruplex of AS1411 combined with hemin (AH) catalyzes the generation of oxygen from hydrogen peroxide to further improve the efficiency of PDT. The synergistic therapeutic effect of the cascade reactor is evaluated through in vivo and in vitro experiments, indicating that this cascade reactor has great potential advantages in the synergistic treatment of cancer.

Synthesis and evaluation of radiolabeled porphyrin derivatives for cancer diagnoses and their nonradioactive counterparts for photodynamic therapy

Radioiodinated porphyrin derivatives and the corresponding nonradioactive iodine introduced compounds, [125I]I-TPPOH ([125I]3), [125I]I-l-tyrosine-TPP ([125I]9), I-TPPOH (3), and I-l-tyrosine-TPP (9) were designed, synthesized, and evaluated by in vitro and in vivo experiments. In cytotoxicity assays, 3 and 9 exhibited significant cytotoxicity under light conditions but did not show significant cytotoxicity without light irradiation. Biodistribution experiments with [125I]3 and [125I]9 showed similar distribution patterns with high retention in tumors. In photodynamic therapeutic (PDT) experiments, 3 and 9 at a dose of 13.6 μmol kg-1 weight with 50 W single light irradiation onto the tumor area significantly inhibited tumor growth. These results indicate that the iodinated porphyrin derivatives [123/natI]3 and [123/natI]9 are promising cancer theranostic agents.

Phenethyl Isothiocyanate-Conjugated Chitosan Oligosaccharide Nanophotosensitizers for Photodynamic Treatment of Human Cancer Cells

The aim of this study is to synthesize phenethyl-conjugated chitosan oligosaccharide (COS) (abbreviated as ChitoPEITC) conjugates and then fabricate chlorin E6 (Ce6)-incorporated nanophotosensitizers for photodynamic therapy (PDT) of HCT-116 colon carcinoma cells. PEITC was conjugated with the amine group of COS. Ce6-incorporated nanophotosensitizers using ChitoPEITC (ChitoPEITC nanophotosensitizers) were fabricated by dialysis method. 1H nuclear magnetic resonance (NMR) spectra showed that specific peaks of COS and PEITC were observed at ChitoPEITC conjugates. Transmission electron microscope (TEM) confirmed that ChitoPEITC nanophotosensitizers have spherical shapes with small hydrodynamic diameters less than 200 nm. The higher PEITC contents in the ChitoPEITC copolymer resulted in a slower release rate of Ce6 from nanophotosensitizers. Furthermore, the higher Ce6 contents resulted in a slower release rate of Ce6. In cell culture study, ChitoPEITC nanophotosensitizers showed low toxicity against normal CCD986Sk human skin fibroblast cells and HCT-116 human colon carcinoma cells in the absence of light irradiation. ChitoPEITC nanophotosensitizers showed a significantly higher Ce6 uptake ratio than that of free Ce6. Under light irradiation, cellular reactive oxygen species (ROS) production of nanophotosensitizers was significantly higher than that of free Ce6. Especially, PEITC and/or ChitoPEITC themselves contributed to the production of cellular ROS regardless of light irradiation. ChitoPEITC nanophotosensitizers showed significantly higher PDT efficacy against HCT-116 cells than that of free Ce6. These results indicate that ChitoPEITC nanophotosensitizers have superior potential in Ce6 uptake, ROS production and PDT efficacy. In the HCT-116 cell-bearing mice tumor-xenograft model, ChitoPEITC nanophotosensitizers efficiently inhibited growth of tumor volume rather than free Ce6. In the animal imaging study, ChitoPEITC nanophotosensitizers were concentrated in the tumor tissue, i.e., fluorescence intensity in the tumor tissue was stronger than that of other tissues. We suggest that ChitoPEITC nanophotosensitizers are a promising candidate for the treatment of human colon cancer cells.

Amphiphilic Cationic Phthalocyanines for Photodynamic Therapy of Cancer

Effective interaction with biomembranes is essential for activity of photosensitizers; however, majority of them are highly charged symmetrical species. Amphiphilic cationic phthalocyanines differing in bulkiness of substitution on lipophilic part (-H, -SMe, -StBu) were therefore prepared. Compounds had high singlet oxygen production (ΦΔ =0.38-0.46, DMSO), good fluorescence emission (ΦF =0.21-0.26, DMSO), and log P values ranging -0.07-1.1 (1-octanol/PBS). Study of interaction with liposomes revealed that also bulky -StBu derivatives are able to enter biomembranes. Detail in vitro studies (toxicity, subcellular localization, type of cell death, and morphology) were performed. Compounds were characterized by excellent EC50 values in range of dozens of nM (HeLa, EA.hy926, MCF-7, HCT116), which were dependent on drug-light interval and reached plateau after 4 h on HeLa cells. Well-balanced lipophilicity with ability to interact with biomembranes rank these derivatives among perspective photosensitizers, even for vascular-targeted PDT (VTP) since they kill EA.hy926 without any preincubation time.

Potential Application of Photosensitizers With High-Z Elements for Synergic Cancer Therapy

The presence of heavy elements in photosensitizers (PS) strongly influences their electronic and photophysical properties, and hence, conjugation of PS with a suitable element is regarded as a potential strategy to improve their photodynamic properties. Moreover, PS conjugated to metal ion or metal complex and heavy atoms such as halogen have attracted considerable attention as promising agents for multimodal or synergistic cancer therapy. These tetrapyrrole compounds depending on the type and nature of the inorganic elements have been explored for photodynamic therapy (PDT), chemotherapy, X-ray photon activation therapy (PAT), and radiotherapy. Particularly, the combination of metal-based PS and X-ray irradiation has been investigated as a promising novel approach for treating deep-seated tumors, which in the case of PDT is a major limitation due to low light penetration in tissue. This review will summarize the present status of evidence on the effect of insertion of metal or halogen on the photophysical properties of PS and the effectiveness of various metal and halogenated PS investigated for PDT, chemotherapy, and PAT as mono and/or combination therapy.

The zoonosis sporotrichosis can be successfully treated by photodynamic therapy: A scoping review

Sporotrichosis is a worldwide zoonosis, prevalent in tropical and subtropical regions. In recent years, there has been a substantial increase in human and feline cases reported in Brazil. Despite this, the antifungal treatment for sporotrichosis is still limited, and thus, research into new therapeutic modalities must be encouraged. Recently, photodynamic therapy has been introduced as a treatment for sporotrichosis. This work presents an overview of both in vitro and in vivo studies that have used photodynamic therapy in the context of photoinactivation of Sporothrix species. Until now, as far as the authors are aware, this is the first scope review specifically on photodynamic therapy for the treatment of sporotrichosis. A systematic electronic search was conducted in two databases: Web of Science and PubMed. Seven original articles published from 2010 to July 2021 were selected, six of which met the proposed inclusion and exclusion criteria and were considered in this scoping review. Concerning the photoinactivation of Sporothrix spp. the results have been promising as studies, in both animals and humans, have reported significant clinical and mycological effects. The most used photosensitizers were methylene blue and its derivatives, and aminolevulinic acid and its methyl derivative, methyl aminolevulinic acid. In conclusion, photodynamic therapy has great potential in treatment of sporotrichosis, as its fungicidal effect both in vitro and in vivo has clearly been demonstrated. Photodynamic therapy could be used in conjunction with classic antifungal agents to optimize treatment outcomes.

Smart nanocomposite assemblies for multimodal cancer theranostics

Despite great strides in anticancer research, performance statistics of current treatment modalities remain dismal, highlighting the need for safe, efficacious strategies for tumour mitigation. Non-invasive fusion technology platforms combining photodynamic, photothermal and hyperthermia therapies have emerged as alternate strategies with potential to meet many of the unmet clinical demands in the domain of cancer. These therapies make use of metallic and magnetic nanoparticles with light absorbing properties, which are manipulated to generate either reactive cytotoxic oxygen species or heat for tumour ablation. Combination therapies integrating light, heat and magnetism-mediated nanoplatforms with the conventional approaches of chemotherapy, radiotherapy and surgery are emerging as precision medicine for targeted interventions against cancer. This article aims to compile recent developments of advanced nanocomposite assemblies that integrate multimodal therapeutics for cancer treatment. Amalgamation of various effective, non-invasive technological platforms such as photodynamic therapy (PDT), photothermal therapy (PTT), magnetic hyperthermia (MHT), and chemodynamic therapy (CDT) have tremendous potential in presenting safe and efficacious solutions to the formidable challenges in cancer therapeutics.

QuatCy-I2 and MHI-I2 in Photodynamic Therapy

MHI-I2 (1) and QuatCy-I2 (2) were compared in terms of properties important for early-stage photodynamic therapy preclinical candidates. Thus, experiments were performed to monitor dark cytotoxicities, light/dark cytotoxicity ratios, selectivity of localization in tumors over other organs, and clearance from the plasma.

Curcumin encapsulation in functional PLGA nanoparticles: A promising strategy for cancer therapies

Nanoparticles have emerged as promising drug delivery systems for the treatment of several diseases. Novel cancer therapies have exploited these particles as alternative adjuvant therapies to overcome the traditional limitations of radio and chemotherapy. Curcumin is a natural bioactive compound found in turmeric, that has been reported to show anticancer activity against several types of tumors. Despite some biological limitations regarding its absorption in the human body, curcumin encapsulation in poly(lactic-co-glycolic acid) (PLGA), a non-toxic, biodegradable and biocompatible polymer, represents an effective strategy to deliver a drug to a tumor site. Furthermore, PLGA nanoparticles can be engineered with targeting moieties to reach specific cancer cells, thus enhancing the antitumor effects of curcumin. We herein aim to bring an up-to-date summary of the recently developed strategies for curcumin delivery to different types of cancer cells through encapsulation in PLGA nanoparticles, correlating their effects with those of curcumin on the biological capabilities acquired by cancer cells (cancer hallmarks). We discuss the targeting strategies proposed for advanced curcumin delivery and the respective improvements achieved for each cancer cell analyzed, in addition to exploring the encapsulation techniques employed. The conjugation of correct encapsulation techniques with tumor-oriented targeting design can result in curcumin-loaded PLGA nanoparticles that can successfully integrate the elaborate network of development of alternative cancer treatments along with traditional ones. Finally, the current challenges and future demands to launch these nanoparticles in oncology are comprehensively examined.

A Photosensitized Singlet Oxygen (1O2) Toolbox for Bio-Organic Applications: Tailoring 1O2 Generation for DNA and Protein Labelling, Targeting and Biosensing

Singlet oxygen (1O2) is the excited state of ground, triplet state, molecular oxygen (O2). Photosensitized 1O2 has been extensively studied as one of the reactive oxygen species (ROS), responsible for damage of cellular components (protein, DNA, lipids). On the other hand, its generation has been exploited in organic synthesis, as well as in photodynamic therapy for the treatment of various forms of cancer. The aim of this review is to highlight the versatility of 1O2, discussing the main bioorganic applications reported over the past decades, which rely on its production. After a brief introduction on the photosensitized production of 1O2, we will describe the main aspects involving the biologically relevant damage that can accompany an uncontrolled, aspecific generation of this ROS. We then discuss in more detail a series of biological applications featuring 1O2 generation, including protein and DNA labelling, cross-linking and biosensing. Finally, we will highlight the methodologies available to tailor 1O2 generation, in order to accomplish the proposed bioorganic transformations while avoiding, at the same time, collateral damage related to an untamed production of this reactive species.

Photophysical characterization and in vitro anti-leishmanial effect of 5,10,15,20-tetrakis(4-fluorophenyl) porphyrin and the metal (Zn(II), Sn(IV), Mn(III) and V(IV)) derivatives

In this report 5 compounds were synthesized and structural and their photophysical characterization was performed (Φ_Δ and Φ_f). Furthermore, in this in vitro study, their biological activity against Leishmania panamensis was evaluated. The photophysical behavior of these compounds was measured and high Φ_Δ and low Φ_f was observed. Besides, DFT quantum calculations on the electronic structures were performed. Finally, the biological activity was determined by means of the compounds capacity to inhibit the viability of parasites using the MTT assay. The inclusion of the metal ions substantially modified the photophysical and biological properties in comparison with the free metal porphyrin (1). In fact, Zn²⁺ porphyrin derivative (2) showed a marked decrease of Φ_f and increase of Φ_Δ. In this sense, using TDDFT approaches, a luminescent process for Sn⁴⁺ derivative (3) was described, where emissive states involve the ML-LCT transition. So, this led to a decrease in the singlet oxygen production (0.82-0.67). Biological results showed that all compounds inhibit the viability of L. panamensis with high efficiency; the decrease in the viability was greater as the concentration of exposure increased. Finally, under light irradiation the IC₅₀ of L. panamensis against the Zn(II)-porphyrin (2) and V(IV)-porphyrin (5) was lower than the IC₅₀ of the Glucantime control (IC₅₀ = 2.2 and 6.95 μM Vs IC₅₀ = 12.7 μM, respectively). We showed that the use of porphyrin and metalloporphyrin-type photosensitizers with exceptional photophysical properties can be successful in photodynamic therapy (PDT) against L. panamensis, being the diamagnetic ion Zn²⁺ a candidate for the preparation of metalloporphyrins with high singlet oxygen production.

Photodynamic therapy with mitochondria-targeted biscyclometallated Ir(III) complexes. Multi-action mechanism and strong influence of the cyclometallating ligand

Photodynamic therapy is an alternative to classical chemotherapy due to its potential to reduce side effects by a controlled activation of a photosensitizer through local irradiation with light. The photosensitizer then interacts with oxygen and generates reactive oxygen species. Iridium biscyclometallated complexes are very promising photosensitizers due to their exceptional photophysical properties and their ability to target mitochondria. Four Ir(III) biscyclometallated complexes of formula [Ir(C^N)₂(N^N')]Cl, where N^N' is a ligand containing a benzimidazolyl fragment, have been synthesized and characterized. The C^N ligands were 2-phenylpyridinate (ppy) and 2-(2,4-difluorophenyl)pyridinate (dfppy). The complexes exhibited high photostability. The electrochemical and photophysical properties were modulated by both the cyclometallating and the ancillary ligands. The dfppy derivatives yielded the highest emission energy values, quantum yields of phosphorescence and excited state lifetimes. All complexes generated ¹O₂ in aerated solutions upon irradiation. Biological studies revealed that these complexes have a moderate cytotoxicity in the dark against different human cancer cell lines: prostate (PC-3), colon (CACO-2) and melanoma (SK-MEL-28), and against non-malignant fibroblasts (CCD-18Co). However, derivatives with ppy ligands ([1a]Cl, [2a]Cl) yielded a relevant photodynamic activity upon light irradiation (450 nm, 24.1 J cm^-2), with phototoxicity indexes (EC_50,dark/EC_50,light) of 20.8 and 17.3, respectively, achieved in PC-3 cells. Mechanistic studies showed that these complexes are taken up by the cells through endocytosis and preferentially accumulate in mitochondria. Upon photoactivation, the complexes induced mitochondrial membrane depolarization and DNA damage, thus triggering cell death, mainly by apoptosis. Complex [1a]Cl is also able to oxidize NADH. This mitochondria-targeted photodynamic mechanism greatly inhibited the reproductive capacity of cancer cells and provides a valuable alternative to traditional chemotherapy for the controlled treatment of cancer.

In vitro assessment of synergistic effects in combinations of a temoporfin-based photodynamic therapy with glutathione peroxidase 1 inhibitors

BACKGROUND

Due to an increased elimination of reactive oxygen species (ROS), in particular hydrogen peroxide (H₂O₂), overexpression of glutathione peroxidase 1 (GP_X1) can lead to an attenuation of apoptosis and development of resistance in cancer cells, thereby promoting tumor cell survival. Consequently, GP_X1 inhibitors have the potential to be used in cancer therapy as they support oxidative stress in cancer cells. Similarly, photodynamic therapy (PDT) induces oxidative stress in cancer cells by the formation of ROS upon illumination. Thus, both methods of treatment might act in synergy when used in combination.

METHODS

To investigate this hypothesis, combinations of the known GP_X1 inhibitors 9-chloro-6-ethyl-6H-[1,2,3,4,5]pentathiepino[6,7-b]indole (CEPI) or mercaptosuccinic acid (MSA) with PDT induced by the photosensitizer (PS) temoporfin (5,10,15,20-tetra(m-hydroxyphenyl)chlorin, mTHPC) were studied in vitro. This new combinatory approach was intended to accumulate ROS formed during PDT via blockage of GP_X1-catalyzed H₂O₂ degradation, and thus to enhance PDT-induced phototoxicity. Five human cancer cell lines from tumor origins treatable with PDT were utilized to investigate ROS generation, apoptosis induction, and cell cycle distribution.

RESULTS

Synergy was identified with both GP_X1 inhibitors, but not in all cell lines. ROS levels were increased after combined treatment with mTHPC and CEPI, but not MSA, in some cell lines, indicating that oxidative stress and ROS accumulation were enhanced by CEPI. Surprisingly, enhanced apoptosis induction was also observed with MSA afterwards, suggesting that other pathways contributed to the initiation of apoptosis. Cell cycle analysis confirmed apoptosis induction via the detection of DNA fragmentation.

CONCLUSION

A combination of GP_X1 inhibitors with mTHPC-PDT has the potential to generate synergistic effects and to increase overall phototoxicity, but the success of this combination approach was dependent on cancer type, and even antagonistic effects can occur.

Phototherapy and optical waveguides for the treatment of infection

With rapid emergence of multi-drug resistant microbes, it is imperative to seek alternative means for infection control. Optical waveguides are an auspicious delivery method for precise administration of phototherapy. Studies have shown that phototherapy is promising in fighting against a myriad of infectious pathogens (i.e. viruses, bacteria, fungi, and protozoa) including biofilm-forming species and drug-resistant strains while evading treatment resistance. When administered via optical waveguides, phototherapy can treat both superficial and deep-tissue infections while minimizing off-site effects that afflict conventional phototherapy and pharmacotherapy. Despite great therapeutic potential, exact mechanisms, materials, and fabrication designs to optimize this promising treatment option are underexplored. This review outlines principles and applications of phototherapy and optical waveguides for infection control. Research advances, challenges, and outlook regarding this delivery system are rigorously discussed in a hope to inspire future developments of optical waveguide-mediated phototherapy for the management of infection and beyond.

Targeted Photodynamic Diagnosis and Therapy for Esophageal Cancer: Potential Role of Functionalized Nanomedicine

Esophageal cancer is often diagnosed at the late stage when cancer has already spread and is characterized by a poor prognosis. Therefore, early diagnosis is vital for a better and efficient treatment outcome. Upper endoscopy with biopsy is the standard diagnostic tool for esophageal cancer but is challenging to diagnose at its premalignant stage, while conventional treatments such as surgery, chemotherapy, and irradiation therapy, are challenging to eliminate the tumor. Photodynamic diagnosis (PDD) and therapy (PDT) modalities that employ photosensitizers (PSs) are emerging diagnostic and therapeutic strategies for esophageal cancer. However, some flaws associated with the classic PSs have limited their clinical applications. Functionalized nanomedicine has emerged as a potential drug delivery system to enhance PS drug biodistribution and cellular internalization. The conjugation of PSs with functionalized nanomedicine enables increased localization within esophageal cancer cells due to improved solubility and stability in blood circulation. This review highlights PS drugs used for PDD and PDT for esophageal cancer. In addition, it focuses on the various functionalized nanomedicine explored for esophageal cancer and their role in targeted PDD and PDT for diagnosis and treatment.

Highly Potent Photoinactivation of Bacteria Using a Water-Soluble, Cell-Permeable, DNA-Binding Photosensitizer

Antimicrobial photodynamic therapy (APDT) employs a photosensitizer, light, and molecular oxygen to treat infectious diseases via oxidative damage, with a low likelihood for the development of resistance. For optimal APDT efficacy, photosensitizers with cationic charges that can permeate bacteria cells and bind intracellular targets are desired to not limit oxidative damage to the outer bacterial structure. Here we report the application of brominated DAPI (Br-DAPI), a water-soluble, DNA-binding photosensitizer for the eradication of both Gram-negative and Gram-positive bacteria (as demonstrated on N99 Escherichia coli and Bacillus subtilis, respectively). We observe intracellular uptake of Br-DAPI, ROS-mediated bacterial cell death via one- and two-photon excitation, and selective photocytotoxicity of bacteria over mammalian cells. Photocytotoxicity of both N99 E. coli and B. subtilis occurred at submicromolar concentrations (IC₅₀ = 0.2-0.4 μM) and low light doses (5 min irradiation times, 4.5 J cm^-2 dose), making it superior to commonly employed APDT phenothiazinium photosensitizers such as methylene blue. Given its high potency and two-photon excitability, Br-DAPI is a promising novel photosensitizer for in vivo APDT applications.

Miniatured Fluidics-Mediated Modular Self-Assembly of Anticancer Drug-Amino Acid Composite Microbowls for Combined Chemo-Photodynamic Therapy in Glioma

A particulate carrier with the ability to load a combination of therapeutic molecules acting via diverse modes to initiate cancer cell ablation would help heighten anticancer therapeutic outcomes and mitigate harmful side effects due to high doses of mono drug therapy. Moving a step closer, herein, we have developed doxorubicin-curcumin-amino acid-based composite microbowls (CMBs) following miniaturized fluid flow-based self-assembly. The CMBs were further exploited as dual chemo-photodynamic therapeutic agents in C6 glioma cells cultured in both two-dimensional (2D) monolayer and as three-dimensional (3D) spheroids. These CMBs showed synergistic and visible (blue)-light-sensitive cell-killing effects in both C6 cells and 3D spheroids. Furthermore, these bowl-shaped structures also demonstrated good stability and excellent in vitro cytocompatibility in C6 glioma cells. Our results indicated that CMBs with asymmetric cavities could potentially be used as a combinatorial drug carrier enabling simultaneous chemo- and phototherapy for effective cancer treatment. The use of blue light, from the visible part of the electromagnetic system, to generate the phototherapeutic effect further advocates for the ease and widespread applicability of the systems.

Metal Nanoparticles for Photodynamic Therapy: A Potential Treatment for Breast Cancer

Breast cancer (BC) is the most common malignant tumor in women worldwide, which seriously threatens women’s physical and mental health. In recent years, photodynamic therapy (PDT) has shown significant advantages in cancer treatment. PDT involves activating photosensitizers with appropriate wavelengths of light, producing transient levels of reactive oxygen species (ROS). Compared with free photosensitizers, the use of nanoparticles in PDT shows great advantages in terms of solubility, early degradation, and biodistribution, as well as more effective intercellular penetration and targeted cancer cell uptake. Under the current circumstances, researchers have made promising efforts to develop nanocarrier photosensitizers. Reasonably designed photosensitizer (PS) nanoparticles can be achieved through non-covalent (self-aggregation, interfacial deposition, interfacial polymerization or core-shell embedding and physical adsorption) or covalent (chemical immobilization or coupling) processes and accumulate in certain tumors through passive and/or active targeting. These PS loading methods provide chemical and physical stability to the PS payload. Among nanoparticles, metal nanoparticles have the advantages of high stability, adjustable size, optical properties, and easy surface functionalization, making them more biocompatible in biological applications. In this review, we summarize the current development and application status of photodynamic therapy for breast cancer, especially the latest developments in the application of metal nanocarriers in breast cancer PDT, and highlight some of the recent synergistic therapies, hopefully providing an accessible overview of the current knowledge that may act as a basis for new ideas or systematic evaluations of already promising results.

Synthesis, photophysical properties and photodynamic antimicrobial activity of meso 5,10,15,20-tetra(pyren-1-yl)porphyrin and its indium(III) complex

In this study, free-base meso 5,10,15,20-tetra(pyren-1-yl)porphyrin (H2TPyP) and its corresponding indium(III) complex (InClTPyP) were synthesized and characterized on the basis of mass spectrometry, 1H NMR spectroscopy and elemental analysis. InClTPyP was obtained in good yield by treating the free base H2TPyP with indium(III) chloride. Purification of these compounds was achieved through column chromatography using different solvent systems. Metallation of the free base to form a metallo-porphyrin afforded improved photophysical properties. There was a bathochromic shift in wavelength of absorption from the parent free base H2TPyP ([Formula: see text] = 431 nm) to metallated indium(III) complex ([Formula: see text] = 443 nm). The fluorescence quantum yield in H2TPyP was higher ([Formula: see text] = 0.131) than in InClTPyP ([Formula: see text] = 0.017) due to efficient intersystem crossing to the triplet manifold in the metallated porphyrin. Upon illumination, both H2TPyP and InClTPyP show effective dose dependent antimicrobial activity against Staphylococcus aureus with photoinactivation IC[Formula: see text] values of 27.89 and 16.67 [Formula: see text]M, respectively.

A versatile nanoplatform based on multivariate porphyrinic metal-organic frameworks for catalytic cascade-enhanced photodynamic therapy

In recent years, the antitumor application of photodynamic therapy (PDT) has gained widespread interest in treating solid tumors. Due to the hypoxic environment in tumors, the major limit of PDT seems to be the source of oxygen. In this work, we attempted to relieve hypoxia and enhance photodynamic therapy, and therefore, designed and assembled a catalytic cascade-enhanced PDT multifunctional nanoplatform. The mentioned platform termed UIO@Ca-Pt is based on porphyrinic metal-organic framework (UIO) combination, which is simultaneously loaded by CaO2 NPs with polydopamine (PDA) and then the Pt raw material to further improve biocompatibility and efficiency. In a tumor microenvironment, CaO2 could react with water to generate calcium hydroxide and hydrogen peroxide, which was further decomposed by Pt nanoparticles to form oxygen, thereby facilitating the generation of cytotoxic singlet oxygen by photosensitizer TCPP under laser irradiation. Both in vitro and in vivo experiment results confirmed the excellent oxygen production capacity and enhanced PDT effect of UIO@Ca-Pt. With guaranteed safety in PDT, the oxygen-supplying strategy might stimulate considerable interest in the development of various metal-organic materials with multifunctionality for tumor diagnosis and therapy.

Antimicrobial photodynamic therapy (aPDT) for biofilm treatments. Possible synergy between aPDT and pulsed electric fields

Currently, microbial biofilms have been the cause of a wide variety of infections in the human body, reaching 80% of all bacterial and fungal infections. The biofilms present specific properties that increase the resistance to antimicrobial treatments. Thus, the development of new approaches is urgent, and antimicrobial photodynamic therapy (aPDT) has been shown as a promising candidate. aPDT involves a synergic association of a photosensitizer (PS), molecular oxygen and visible light, producing highly reactive oxygen species (ROS) that cause the oxidation of several cellular components. This therapy attacks many components of the biofilm, including proteins, lipids, and nucleic acids present within the biofilm matrix; causing inhibition even in the cells that are inside the extracellular polymeric substance (EPS). Recent advances in designing new PSs to increase the production of ROS and the combination of aPDT with other therapies, especially pulsed electric fields (PEF), have contributed to enhanced biofilm inhibition. The PEF has proven to have antimicrobial effect once it is known that extensive chemical reactions occur when electric fields are applied. This type of treatment kills microorganisms not only due to membrane rupture but also due to the formation of reactive compounds including free oxygen, hydrogen, hydroxyl and hydroperoxyl radicals. So, this review aims to show the progress of aPDT and PEF against the biofilms, suggesting that the association of both methods can potentiate their effects and overcome biofilm infections.