Liposomal formulations of photosensitizers

Twisted Intramolecular Charge Transfer-Based Viscosity-Responsive Probe Reveals Lysosomal Degradation Process of Endocytosed Foreign Bodies

The optimization of nanomedicines requires a thorough understanding of nanocarrier attrition during lysosome-mediated biological processes. Real-time monitoring of endocytosis provides valuable insights into the lysosomal effects on nanocarriers and the release of nanodrugs. We report the development of a coresponsive probe that detects changes in the spatial viscosity of the intracellular domain caused by lysosomal degradation of foreign bodies. The probe, based on a benzofuro[2,3-d]pyrimidine structure, exhibits torsional intramolecular charge transfer (TICT) and responds to ambient viscosity changes with a sensitive fluorescence intensity. The antidiffused fluorescence transition of the probe in the spatially restricted domain serves as a key indicator for real-time monitoring. When encapsulated with diverse foreign bodies and emitted into macrophages by endocytosis, the probe forms nanoparticles. Lysosomes uptake these materials for intracellular digestion, causing alterations in the aggregation or depolymerization state of the nanoparticles, leading to viscosity changes manifested by the probe's fluorescence. By studying the spatial viscosity changes caused by lysosomal degradation of foreign bodies, our monitoring strategy contributes to understanding the digestion or escape capabilities of potential pharmaceutical-carrying nanocarriers, providing guidelines to design more effective nanocarriers that navigate lysosomal degradation to achieve precise drug payloads and release.

A Physiochemical, In Vitro, and In Vivo Comparative Analysis of Verteporfin-Lipid Conjugate Formulations: Solid Lipid Nanoparticles and Liposomes

VisudyneⓇ, a liposomal formulation of verteporfin (benzoporphyrin derivative; BPD), is the only nanomedicine approved to date for photodynamic therapy (PDT). We have previously demonstrated that BPD conjugated to the lysophospholipid 1-arachidoyl-2-hydroxy-sn-glycero-3-phosphocholine (BPD-PC) exhibits the greatest physical stability in liposomes, while maintaining cancer cell phototoxicity, from a panel of BPD lipid conjugates evaluated. In this study, we prepared 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC)-based solid lipid nanoparticles (LNPs) that stably entrap BPD-PC, which resemble the composition of the SpikevaxⓇ Moderna COVID-19 vaccine, and compared them to a DPPC based liposomal formulation (Lipo BPD-PC). We evaluated the photochemical, optical, and phototherapeutic properties of both formulations. We also investigated the in vivo distribution and tumor microdistribution of both formulations. Our results demonstrated that Lipo BPD-PC is able to generate 17% more singlet oxygen than LNP BPD-PC, while interestingly, LNP BPD-PC is able to produce 76% more hydroxyl radicals and/or peroxynitrite anion. Importantly, only 28% of BPD-PC leaches out of the LNP BPD-PC formulation during 7 days of incubation in serum at 37 °C, while 100% of BPD-PC leaches out of the Lipo BPD-PC formulation under the same conditions. Despite these differences, there was no significant difference in cellular uptake of BPD-PC or phototoxicity in CT1BA5 murine pancreatic cancer cells (derived from a genetically engineered mouse model). Interestingly, PDT using LNP BPD-PC was more efficient at inducing immunogenic cell death (calreticulin membrane translocation) than Lipo BPD-PC when using IC25 and IC50 PDT doses. In vivo studies revealed that CT1BA5 tumor fluorescence signals from BPD-PC were 2.41-fold higher with Lipo BPD-PC than with LNP BPD-PC; however, no significant difference was observed in tumor tissue selectivity or tumor penetration. As such, we present LNP BPD-PC as a unique and more stable nanoplatform to carry BPD lipid conjugates, such as BPD-PC, with a potential for future photodynamic immune priming studies and multiagent drug delivery.

Supramolecular dye nanoassemblies for advanced diagnostics and therapies

Dyes have conventionally been used in medicine for staining cells, tissues, and organelles. Since these compounds are also known as photosensitizers (PSs) which exhibit photoresponsivity upon photon illumination, there is a high desire towards formulating these molecules into nanoparticles (NPs) to achieve improved delivery efficiency and enhanced stability for novel imaging and therapeutic applications. Furthermore, it has been shown that some of the photophysical properties of these molecules can be altered upon NP formation thereby playing a major role in the outcome of their application. In this review, we primarily focus on introducing dye categories, their formulation strategies and how these strategies affect their photophysical properties in the context of photothermal and non-photothermal applications. More specifically, the most recent progress showing the potential of dye supramolecular assemblies in modalities such as photoacoustic and fluorescence imaging, photothermal and photodynamic therapies as well as their employment in photoablation as a novel modality will be outlined. Aside from their photophysical activity, we delve shortly into the emerging application of dyes as drug stabilizing agents where these molecules are used together with aggregator molecules to form stable nanoparticles.

Construction Strategy of Functionalized Liposomes and Multidimensional Application

Liposomes are widely used in the biological field due to their good biocompatibility and surface modification properties. With the development of biochemistry and material science, many liposome structures and their surface functional components have been modified and optimized one by one, pushing the liposome platform from traditional to functionalized and intelligent, which will better satisfy and expand the needs of scientific research. However, a main limiting factor effecting the efficiency of liposomes is the complicated environmental conditions in the living body. Currently, in order to overcome the above problem, functionalized liposomes have become a very promising strategy. In this paper, binding strategies of liposomes with four main functional elements, namely nucleic acids, antibodies, peptides, and stimuli-responsive motif have been summarized for the first time. In addition, based on the construction characteristics of functionalized liposomes, such as drug-carrying, targeting, long-circulating, and stimulus-responsive properties, a comprehensive overview of their features and respective research progress are presented. Finally, the paper critically presents the limitations of these functionalized liposomes in the current applications and also prospectively suggests the future development directions, aiming to accelerate realization of their industrialization.

Carrier-Free, Amorphous Verteporfin Nanodrug for Enhanced Photodynamic Cancer Therapy and Brain Drug Delivery

Glioblastoma (GBM) is hard to treat due to cellular invasion into functioning brain tissues, limited drug delivery, and evolved treatment resistance. Recurrence is nearly universal even after surgery, chemotherapy, and radiation. Photodynamic therapy (PDT) involves photosensitizer administration followed by light activation to generate reactive oxygen species at tumor sites, thereby killing cells or inducing biological changes. PDT can ablate unresectable GBM and sensitize tumors to chemotherapy. Verteporfin (VP) is a promising photosensitizer that relies on liposomal carriers for clinical use. While lipids increase VP's solubility, they also reduce intracellular photosensitizer accumulation. Here, a pure-drug nanoformulation of VP, termed "NanoVP", eliminating the need for lipids, excipients, or stabilizers is reported. NanoVP has a tunable size (65-150 nm) and 1500-fold higher photosensitizer loading capacity than liposomal VP. NanoVP shows a 2-fold increase in photosensitizer uptake and superior PDT efficacy in GBM cells compared to liposomal VP. In mouse models, NanoVP-PDT improved tumor control and extended animal survival, outperforming liposomal VP and 5-aminolevulinic acid (5-ALA). Moreover, low-dose NanoVP-PDT can safely open the blood-brain barrier, increasing drug accumulation in rat brains by 5.5-fold compared to 5-ALA. NanoVP is a new photosensitizer formulation that has the potential to facilitate PDT for the treatment of GBM.

Advances in liposomes loaded with photoresponse materials for cancer therapy

Cancer treatment is presently a significant challenge in the medical domain, wherein the primary modalities of intervention include chemotherapy, radiation therapy and surgery. However, these therapeutic modalities carry side effects. Photothermal therapy (PTT) and photodynamic therapy (PDT) have emerged as promising modalities for the treatment of tumors in recent years. Phototherapy is a therapeutic approach that involves the exposure of materials to specific wavelengths of light, which can subsequently be converted into either heat or Reactive Oxygen Species (ROS) to effectively eradicate cancer cells. Due to the hydrophobicity and lack of targeting of many photoresponsive materials, the use of nano-carriers for their transportation has been extensively explored. Among these nanocarriers, liposomes have been identified as an effective drug delivery system due to their controllability and availability in the biomedical field. By binding photoresponsive materials to liposomes, it is possible to reduce the cytotoxicity of the material and regulate drug release and accumulation at the tumor site. This article provides a comprehensive review of the progress made in cancer therapy using photoresponsive materials loaded onto liposomes. Additionally, the article discusses the potential synergistic treatment through the combination of phototherapy with chemo/immuno/gene therapy using liposomes.

In Vitro Antimicrobial Photodynamic Therapy for Pseudomonas aeruginosa (P. aeruginosa) and methicillin-resistant Staphylococcus aureus (MRSA) Inhibition Using a Green Light Source

Photodynamic therapy (PDT) has been based on using photosensitizers (PS) and applying light of a specific wavelength. When this technique is used for treating infections, it is known as antimicrobial photodynamic therapy (aPDT). Currently, the use of lighting sources for in vitro studies using aPDT is generally applied in multiwell cell culture plates; however, depending on the lighting arrangement, there are usually errors in the application of the technique because the light from a well can affect the neighboring wells or it may be that not all the wells are used in the same experiment. In addition, one must be awarded high irradiance values, which can cause unwanted photothermal problems in the studies. Thus, this manuscript presents an in vitro antimicrobial photodynamic therapy for a Pseudomonas aeruginosa (P. aeruginosa) and methicillin-resistant Staphylococcus aureus (MRSA) inhibition study using an arrangement of thermally isolated and independently illuminated green light source systems for eight tubes in vitro aPDT, determining the effect of the following factors: (i) irradiance level, (ii) exposure time, and (iii) Rose Bengal (RB) concentration (used as a PS), registering the Pseudomonas aeruginosa (P. aeruginosa) and methicillin-resistant Staphylococcus aureus (MRSA) inhibition rates. The results show that in the dark, RB had a poor antimicrobial rate for P. aeruginosa, finding the maximum inhibition (2.7%) at 30 min with an RB concentration of 3 µg/mL. However, by applying light in a correct dosage (time × irradiance) and the adequate RB concentration, the inhibition rate increased by over 37%. In the case of MRSA, there was no significant inhibition with RB in complete darkness and, in contrast, the rate was 100% for those experiments that were irradiated.

Salvianolic acid B as a potent nano-agent for enhanced ALA-PDT of oral cancer and leukoplakia cells

BACKGROUND

Photodynamic therapy (PDT) relies on the light activation of a photosensitizers to generate reactive oxygen species such as singlet oxygen, but its effect on cancer therapy is limited dramatically by hypoxia in the tumor microenvironment.

OBJECTIVES

To determine the potential of a nano-photosensitizer loaded salvianolic acid B (SalB) and 5-aminolevulinic acid (ALA) for enhancing the efficacy of PDT in oral squamous cell carcinoma Cal27 cells and leukoplakia Leuk1 cells.

RESULTS

Singlet oxygen sensor green (SOSG) assay showed that nano-SalB-ALA generated higher levels of singlet oxygen, compared to nano-SalB and nano-ALA. Cellular uptake assay showed that nano-SalB-ALA effectively absorbed by Leuk1 cells. Importantly, cell counting kit-8 and flow cytometry revealed that PDT with nano-SalB-ALA effectively inhibited the viability and induced the apoptosis of Cal27 and Leuk1 cells, respectively. Moreover, the tumor xenograft study revealed that PDT with nano-SalB-ALA had a stronger inhibitory effect on tumor growth of nude mice, compared to control groups.

CONCLUSIONS

The novel photosensitizer nano-SalB-ALA remarkably enhanced the efficacy of PDT by improving singlet oxygen production, inhibiting cell proliferation, promoting cell apoptosis, and suppressing tumor growth. These suggest PDT with nano-SalB-ALA could be a clinically significant and potent treatment for oral cancer and leukoplakia.

Shedding Light on Chemoresistance: The Perspective of Photodynamic Therapy in Cancer Management

The persistent failure of standard chemotherapy underscores the urgent need for innovative and targeted approaches in cancer treatment. Photodynamic therapy (PDT) has emerged as a promising photochemistry-based approach to address chemoresistance in cancer regimens. PDT not only induces cell death but also primes surviving cells, enhancing their susceptibility to subsequent therapies. This review explores the principles of PDT and discusses the concept of photodynamic priming (PDP), which augments the effectiveness of treatments like chemotherapy. Furthermore, the integration of nanotechnology for precise drug delivery at the right time and location and PDT optimization are examined. Ultimately, this study highlights the potential and limitations of PDT and PDP in cancer treatment paradigms, offering insights into future clinical applications.

Light-Induced Liposomal Drug Delivery with an Amphiphilic Porphyrin and Its Chlorin and Bacteriochlorin Analogues

The development of targeted drug delivery mechanisms in the human body is a matter of growing interest in medical science. The selective release of therapeutic agents at a specific target site can increase the therapeutical efficiency and at the same time reduce the side effects. Light-sensitive liposomes can release a drug by an externally controlled light trigger. Liposomes containing photosensitizers that can be activated in the longer wavelength range (650-800 nm) are particularly intriguing for medical purposes. This is because light penetration into a tissue is more efficient within this wavelength range, increasing their potential applications. For this study, liposomes with an encapsulated amphiphilic photosensitizer, the porphyrin 5,10-DiOH (5,10-di(4-hydroxyphenyl)-15,20-diphenyl-21,23H-porphyrin), its chlorin (5,10-DiOH-chlorin) and its bacteriochlorin (5,10-DiOH-bacteriochlorin) were synthesized. The porphyrin 5,10-DiOH showed previously effective cargo release after liposomal encapsulation when irradiated at a wavelength of 420 nm. The new synthesized chlorin and bacteriochlorin photosensitizers show additional absorption bands in the longer wavelength range, which would enable excitation in deeper layers of tissue. Effective cargo release with chlorin at a longer wavelength of 650 nm and bacteriochlorin at 740 nm was possible. Irradiation of chlorin allowed more than 75% of the cargo to be released and more than 60% for bacteriochlorin. The new liposomes would enable selective drug release in deeper tissue layers and expand the range of possible applications.

Nanocarriers in topical photodynamic therapy

INTRODUCTION

Photodynamic therapy (PDT) has gained significant attention due to its superiority over conventional treatments. In the context of skin cancers and nonmalignant skin diseases, topical application of photosensitizer formulations onto affected skin, followed by illumination, offers distinct advantages. Topical PDT simplifies therapy by providing easy access to the skin, increasing drug concentration within the target area, and confining residual photosensitivity to the treated skin. However, the effectiveness of topical PDT is often hindered by challenges such as limited skin penetration or photosensitizer instability. Additionally, the hypoxic tumor environment poses further limitations. Nanocarriers present a promising solution to address these challenges.

AREAS COVERED

The objective of this review is to comprehensively explore and highlight the role of various nanocarriers in advancing topical PDT for the treatment of skin diseases. The primary focus is to address the challenges associated with conventional topical PDT approaches and demonstrate how nanotechnology-based strategies can overcome these challenges, thereby improving the overall efficiency and efficacy of PDT.

EXPERT OPINION

Nanotechnology has revolutionized the field of PDT, offering innovative tools to combat the unfavorable features of photosensitizers and hurdles in PDT. Nanocarriers enhance skin penetration and stability of photosensitizers, provide controlled drug release, reduce needed dose, increase production of reactive oxygen species, while reducing side effects, thereby improving PDT effectiveness.

Nanoscale Covalent Organic Framework with Staggered Stacking of Phthalocyanines for Mitochondria-Targeted Photodynamic Therapy

Phthalocyanine photosensitizers (PSs) have shown promise in fluorescence imaging and photodynamic therapy (PDT) of malignant tumors, but their practical application is limited by the aggregation-induced quenching (AIQ) and inherent photobleaching of PSs. Herein, we report the synthesis of a two-dimensional nanoscale covalent organic framework (nCOF) with staggered (AB) stacking of zinc-phthalocyanines (ZnPc), ZnPc-PI, for fluorescence imaging and mitochondria-targeted PDT. ZnPc-PI isolates and confines ZnPc PSs in the rigid nCOF to reduce AIQ, improve photostability, enhance cellular uptake, and increase the level of reactive oxygen species (ROS) generation via mitochondrial targeting. ZnPc-PI shows efficient tumor accumulation, which allowed precise tumor imaging and nanoparticle tracking. With high cellular uptake and tumor accumulation, intrinsic mitochondrial targeting, and enhanced ROS generation, ZnPc-PI exhibits potent PDT efficacy with >95% tumor growth inhibition on two murine colon cancer models without causing side effects.

Overview of Recent Advances in Nano-Based Ocular Drug Delivery

Ocular diseases profoundly impact patients' vision and overall quality of life globally. However, effective ocular drug delivery presents formidable challenges within clinical pharmacology and biomaterial science, primarily due to the intricate anatomical and physiological barriers unique to the eye. In this comprehensive review, we aim to shed light on the anatomical and physiological features of the eye, emphasizing the natural barriers it presents to drug administration. Our goal is to provide a thorough overview of various characteristics inherent to each nano-based drug delivery system. These encompass nanomicelles, nanoparticles, nanosuspensions, nanoemulsions, microemulsions, nanofibers, dendrimers, liposomes, niosomes, nanowafers, contact lenses, hydrogels, microneedles, and innovative gene therapy approaches employing nano-based ocular delivery techniques. We delve into the biology and methodology of these systems, introducing their clinical applications over the past decade. Furthermore, we discuss the advantages and challenges illuminated by recent studies. While nano-based drug delivery systems for ophthalmic formulations are gaining increasing attention, further research is imperative to address potential safety and toxicity concerns.

Pediatric Drug Development: Reviewing Challenges and Opportunities by Tracking Innovative Therapies

The paradigm of pediatric drug development has been evolving in a "carrot-and-stick"-based tactic to address population-specific issues. However, the off-label prescription of adult medicines to pediatric patients remains a feature of clinical practice, which may compromise the age-appropriate evaluation of treatments. Therefore, the United States and the European Pediatric Formulation Initiative have recommended applying nanotechnology-based delivery systems to tackle some of these challenges, particularly applying inorganic, polymeric, and lipid-based nanoparticles. Connected with these, advanced therapy medicinal products (ATMPs) have also been highlighted, with optimistic perspectives for the pediatric population. Despite the results achieved using these innovative therapies, a workforce that congregates pediatric patients and/or caregivers, healthcare stakeholders, drug developers, and physicians continues to be of utmost relevance to promote standardized guidelines for pediatric drug development, enabling a fast lab-to-clinical translation. Therefore, taking into consideration the significance of this topic, this work aims to compile the current landscape of pediatric drug development by (1) outlining the historic regulatory panorama, (2) summarizing the challenges in the development of pediatric drug formulation, and (3) delineating the advantages/disadvantages of using innovative approaches, such as nanomedicines and ATMPs in pediatrics. Moreover, some attention will be given to the role of pharmaceutical technologists and developers in conceiving pediatric medicines.

Revolutionizing cancer treatment: nanotechnology-enabled photodynamic therapy and immunotherapy with advanced photosensitizers

Nanotechnology-enhanced photodynamic therapy (PDT) and immunotherapy are emerging as exciting cancer therapeutic methods with significant potential for improving patient outcomes. By combining these approaches, synergistic effects have been observed in preclinical studies, resulting in enhanced immune responses to cancer and the capacity to conquer the immunosuppressive tumor microenvironment (TME). Despite challenges such as addressing treatment limitations and developing personalized cancer treatment strategies, the integration of nanotechnology-enabled PDT and immunotherapy, along with advanced photosensitizers (PSs), represents an exciting new avenue in cancer treatment. Continued research, development, and collaboration among researchers, clinicians, and regulatory agencies are crucial for further advancements and the successful implementation of these promising therapies, ultimately benefiting cancer patients worldwide.

Folate-Targeted Nanoliposomal Chemophototherapy

Light-responsive liposomes have been developed for the on-demand release of drugs. However, efficient delivery of chemotherapeutic drugs to tumor for cancer theranostics remains a challenge. Herein, folic acid (FA), an established ligand for targeted drug delivery, was used to decorate light-sensitive porphyrin-phospholipid (PoP) liposomes, which were assessed for FA-targeted chemophototherapy (CPT). PoP liposomes and FA-conjugated PoP liposomes were loaded with Doxorubicin (Dox), and physical properties were characterized. In vitro, FA-PoP liposomes that were incubated with FA receptor-overexpressing human KB cancer cells showed increased uptake compared to non-targeted PoP liposomes. Dox and PoP contributed towards chemophototherapy (CPT) in vitro, and PoP and FA-PoP liposomes induced cell killing. In vivo, mice bearing subcutaneous KB tumors treated with PoP or FA-PoP liposomes loaded with Dox, followed by 665 nm laser treatment, had delayed tumor growth and improved survival. Dox delivery to tumors increased following laser irradiation for both PoP and FA-PoP liposomes. Thus, while Dox-FA-PoP liposomes were effective following systemic administration and local light irradiation in this tumor model, the FA targeting moiety did not appear essential for anti-tumor responses.

Innovative Design Strategies Advance Biomedical Applications of Phthalocyanines

Owing to their long absorption wavelengths, high molar absorptivity, and tunable photosensitivity, phthalocyanines have been widely used in photodynamic therapy (PDT). However, phthalocyanines still face the drawbacks of poor targeting, "always-on" photosensitizing properties, and unsatisfactory therapeutic efficiency, which limit their wide applications in biomedical fields. Thus, new design strategies such as modification of targeting molecules, formation of nanoparticles, and activating photosensitizers are developed to improve the above defects. Notably, recent studies have shown that novel phthalocyanines are not only used in fluorescence imaging and PDT, but also in photoacoustic imaging, photothermal imaging, sonodynamic therapy, and photothermal therapy. This review focuses on recent design strategies, applications in biomedicine, and clinical development of phthalocyanines, providing ideas and references for the design and application of phthalocyanine, so as to promote their future transformation into clinical applications.

Current Strategies in Photodynamic Therapy (PDT) and Photodynamic Diagnostics (PDD) and the Future Potential of Nanotechnology in Cancer Treatment

Photodynamic diagnostics (PDD) and photodynamic therapy (PDT) are well-established medical technologies used for the diagnosis and treatment of malignant neoplasms. They rely on the use of photosensitizers, light and oxygen to visualize or eliminate cancer cells. This review demonstrates the recent advancements in these modalities with the use of nanotechnology, including quantum dots as innovative photosensitizers or energy donors, liposomes and micelles. Additionally, this literature review explores the combination of PDT with radiotherapy, chemotherapy, immunotherapy, and surgery for treating various neoplasms. The article also focuses on the latest achievements in PDD and PDT enhancements, which seem to be very promising in the field of oncology.

Supramolecular Chemotherapy with Cucurbit[n]urils as Encapsulating Hosts

The cucurbit[n]urils (CB[n]) belong to the field of relatively young supramolecules which act as containers for a large variety of guests and are being explored extensively for their numerous biomedical applications. This includes drug formulation and delivery, controlled drug release, photodynamic therapy, sensing for bioanalytical purposes, etc. These supramolecular host-guest systems have distinctive recognition properties and have successfully been shown to enhance the in vitro and in vivo utility of various chemotherapeutic agents. The CB[n]s are tailored to optimize their application in payload delivery and diagnostics and in lowering the toxicity of existing drugs. This review has listed the recent studies on working mechanisms and host-guest complexation of the biologically vital molecules with CB[n] and highlighted their implementation in anticancer therapeutics. Various modifications in CB-drug inclusion compounds like CB supramolecular nanoarchitectures along with application in photodynamic therapy, which has shown potential as targeted drug delivery vehicles in cancer chemotherapy, have also been discussed.

Metal-Organic Layer Delivers 5-Aminolevulinic Acid and Porphyrin for Dual-Organelle-Targeted Photodynamic Therapy

The efficacy of photodynamic therapy (PDT) depends on the subcellular localization of photosensitizers. Herein, we report a dual-organelle-targeted nanoparticle platform for enhanced PDT of cancer. By grafting 5-aminolevulinic acid (ALA) to a Hf12 -based nanoscale metal-organic layer (Hf-MOL) via carboxylate coordination, ALA/Hf-MOL enhanced ALA delivery and protoporphyrin IX (PpIX) synthesis in mitochondria, and trapped the Hf-MOL comprising 5,15-di-p-benzoatoporphyrin (DBP) photosensitizers in lysosomes. Light irradiation at 630 nm simultaneously excited PpIX and DBP to generate singlet oxygen and rapidly damage both mitochondria and lysosomes, leading to synergistic enhancement of the PDT efficacy. The dual-organelle-targeted ALA/Hf-MOL outperformed Hf-MOL in preclinical PDT studies, with a 2.7-fold lower half maximal inhibitory concentration in cytotoxicity assays in vitro and a 3-fold higher cure rate in a colon cancer model in vivo.

2D Nano-Sonosensitizers Facilitate Energy Transfer to Enhance Sonodynamic Therapy

Although sonodynamic therapy (SDT) has shown promise for cancer treatment, the lack of efficient sonosensitizers (SSs) has limited the clinical application of SDT. Here, a new strategy is reported for designing efficient nano-sonosensitizers based on 2D nanoscale metal-organic layers (MOLs). Composed of Hf-oxo secondary building units (SBUs) and iridium-based linkers, the MOL is anchored with 5,10,15,20-tetra(p-benzoato)porphyrin (TBP) sensitizers on the SBUs to afford TBP@MOL. TBP@MOL shows 14.1- and 7.4-fold higher singlet oxygen (1 O2 ) generation than free TBP ligands and Hf-TBP, a 3D nanoscale metal-organic framework, respectively. The 1 O2 generation of TBP@MOL is enhanced by isolating TBP SSs on the SBUs of the MOL, which prevents aggregation-induced quenching of the excited sensitizers, and by triplet-triplet Dexter energy transfer between excited iridium-based linkers and TBP SSs, which more efficiently harnesses broad-spectrum sonoluminescence. Anchoring TBP on the MOL surface also enhances the energy transfer between the excited sensitizer and ground-state triplet oxygen to increase 1 O2 generation efficacy. In mouse models of colorectal and breast cancer, TBP@MOL demonstrates significantly higher SDT efficacy than Hf-TBP and TBP. This work uncovers a new strategy to design effective nano-sonosensitizers by facilitating energy transfer to efficiently capture broad-spectrum sonoluminescence and enhance 1 O2 generation.

Chemophototherapeutic Ablation of Doxorubicin-Resistant Human Ovarian Tumor Cells

Porphyrin-phospholipid (PoP) liposomes loaded with Doxorubicin (Dox) have been demonstrated to be an efficient vehicle for chemophototherapy (CPT). Multidrug resistance (MDR) of cancer cells is a problematic phenomenon in which tumor cells develop resistance to chemotherapy. Herein, we report that Dox-resistant tumor cells can be ablated using our previously described formulation termed long-circulating Dox loaded in PoP liposomes (LC-Dox-PoP), which is a PEGylated formulation containing 2 mol. % of the PoP photosensitizer. In vitro studies using free Dox and LC-Dox-PoP showed that human ovarian carcinoma A2780 cells were more susceptible to Dox compared to the corresponding Dox-resistant A2780-R cells. When CPT was applied with LC-Dox-PoP liposomes, effective killing of both nonresistant and resistant A2780 cell lines was observed. An in vivo study to assess the efficiency of LC-Dox-PoP showed effective tumor shrinkage and prolonged survival of athymic nude mice bearing subcutaneous Dox-resistant A2780-R tumor xenografts when they were irradiated with a red laser. Biodistribution analysis demonstrated enhanced tumoral drug uptake in Dox-resistant tumors with CPT, suggesting that increased drug delivery was sufficient to induce ablation of resistant tumor cells.

A Sulfur-Bridging Sulfonate-Modified Zinc(II) Phthalocyanine Nanoliposome Possessing Hybrid Type I and Type II Photoreactions with Efficient Photodynamic Anticancer Effects

Phthalocyanines are potentially promising photosensitizers (PSs) for photodynamic therapy (PDT), but the inherent defects such as aggregation-caused quenching effects and non-specific toxicity severely hinder their further application in PDT. Herein, we synthesized two zinc(II) phthalocyanines (PcSA and PcOA) monosubstituted with a sulphonate group in the alpha position with "O bridge" and "S bridge" as bonds and prepared a liposomal nanophotosensitizer (PcSA@Lip) by thin-film hydration method to regulate the aggregation of PcSA in the aqueous solution and enhance its tumor targeting ability. PcSA@Lip exhibited highly efficient production of superoxide radical (O₂^∙-) and singlet oxygen (¹O₂) in water under light irradiation, which were 2.6-fold and 15.4-fold higher than those of free PcSA, respectively. Furthermore, PcSA@Lip was able to accumulate selectively in tumors after intravenous injection with the fluorescence intensity ratio of tumors to livers was 4.1:1. The significant tumor inhibition effects resulted in a 98% tumor inhibition rate after PcSA@Lip was injected intravenously at an ultra-low PcSA@Lip dose (0.8 nmol g^-1 PcSA) and light dose (30 J cm^-2). Therefore, the liposomal PcSA@Lip is a prospective nanophotosensitizer possessing hybrid type I and type II photoreactions with efficient photodynamic anticancer effects.

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.

Liposome-based diagnostic and therapeutic applications for pancreatic cancer

Pancreatic cancer is one of the harshest and most challenging cancers to treat, often labeled as incurable. Chemotherapy continues to be the most popular treatment yet yields a very poor prognosis. The main barriers such as inefficient drug penetration and drug resistance, have led to the development of drug carrier systems. The benefits, ease of fabrication and modification of liposomes render them as ideal future drug delivery systems. This review delves into the versatility of liposomes to achieve various mechanisms of treatment for pancreatic cancer. Not only are there benefits of loading chemotherapy drugs and targeting agents onto liposomes, as well as mRNA combined therapy, but liposomes have also been exploited for immunotherapy and can be programmed to respond to photothermal therapy. Multifunctional liposomal formulations have demonstrated significant pre-clinical success. Functionalising drug-encapsulated liposomes has resulted in triggered drug release, specific targeting, and remodeling of the tumor environment. Suppressing tumor progression has been achieved, due to their ability to more efficiently and precisely deliver chemotherapy. Currently, no multifunctional surface-modified liposomes are clinically approved for pancreatic cancer thus we aim to shed light on the trials and tribulations and progress so far, with the hope for liposomal therapy in the future and improved patient outcomes. STATEMENT OF SIGNIFICANCE: Considering that conventional treatments for pancreatic cancer are highly associated with sub-optimal performance and systemic toxicity, the development of novel therapeutic strategies holds outmost relevance for pancreatic cancer management. Liposomes are being increasingly considered as promising nanocarriers for providing not only an early diagnosis but also effective, highly specific, and safer treatment, improving overall patient outcome. This manuscript is the first in the last 10 years that revises the advances in the application of liposome-based formulations in bioimaging, chemotherapy, phototherapy, immunotherapy, combination therapies, and emergent therapies for pancreatic cancer management. Prospective insights are provided regarding several advantages resulting from the use of liposome technology in precision strategies, fostering new ideas for next-generation diagnosis and targeted therapies of pancreatic cancer.

Recent Progress in Carrier-Free Nanomedicine for Tumor Phototherapy

Safe and effective strategies are urgently needed to fight against the life-threatening diseases of various cancers. However, traditional therapeutic modalities, such as radiotherapy, chemotherapy and surgery, exhibit suboptimal efficacy for malignant tumors owing to the serious side effects, drug resistance and even relapse. Phototherapies, including photodynamic therapy (PDT) and photothermal therapy (PTT), are emerging therapeutic strategies for localized tumor inhibition, which can produce a large amount of reactive oxygen species (ROS) or elevate the temperature to initiate cell death by non-invasive irradiation. In consideration of the poor bioavailability of phototherapy agents (PTAs), lots of drug delivery systems have been developed to enhance the tumor targeted delivery. Nevertheless, the carriers of drug delivery systems inevitably bring biosafety concerns on account of their metabolism, degradation, and accumulation. Of note, carrier-free nanomedicine attracts great attention for clinical translation with synergistic antitumor effect, which is characterized by high drug loading, simplified synthetic method and good biocompatibility. In this review, the latest advances of phototherapy with various carrier-free nanomedicines are summarized, which may provide a new paradigm for the future development of nanomedicine and tumor precision therapy.

Targeted implementation strategies of precise photodynamic therapy based on clinical and technical demands

With the development of materials science, photodynamic-based treatments have gradually entered clinics. Photodynamic therapy is ideal for cancer treatment due to its non-invasive and spatiotemporal properties and is the first to be widely promoted in clinical practice. However, the shortcomings resulting from the gap between technical and clinical demands, such as phototoxicity, low tissue permeability, and tissue hypoxia, limit its wide applications. This article reviews the available data regarding the pharmacological and clinical factors affecting the efficacy of photodynamic therapy, such as photosensitizers and oxygen supply, disease diagnosis, and other aspects of photodynamic therapy. In addition, the synergistic treatment of photodynamic therapy with surgery and nanotechnology is also discussed, which is expected to provide inspiration for the design of photodynamic therapy strategies.

Neuro-nanotechnology: diagnostic and therapeutic nano-based strategies in applied neuroscience

Artificial, de-novo manufactured materials (with controlled nano-sized characteristics) have been progressively used by neuroscientists during the last several decades. The introduction of novel implantable bioelectronics interfaces that are better suited to their biological targets is one example of an innovation that has emerged as a result of advanced nanostructures and implantable bioelectronics interfaces, which has increased the potential of prostheses and neural interfaces. The unique physical-chemical properties of nanoparticles have also facilitated the development of novel imaging instruments for advanced laboratory systems, as well as intelligently manufactured scaffolds and microelectrodes and other technologies designed to increase our understanding of neural tissue processes. The incorporation of nanotechnology into physiology and cell biology enables the tailoring of molecular interactions. This involves unique interactions with neurons and glial cells in neuroscience. Technology solutions intended to effectively interact with neuronal cells, improved molecular-based diagnostic techniques, biomaterials and hybridized compounds utilized for neural regeneration, neuroprotection, and targeted delivery of medicines as well as small chemicals across the blood-brain barrier are all purposes of the present article.

Photosensitizers incorporation in SOPC films at different hydration levels

In the present work, two photosensitizing drugs, Temoporfin and Verteporfin have been studied. Both have regular approval in Europe, Temoporfin for the treatment of head and neck cancers and Verteporfin for the treatment of age-related macular degeneration (AMD). The treatment modality, known as "Photodynamic Therapy" (PDT), involves drug activation with visible light in the presence of oxygen and production of reactive oxygen species (ROS) to destroy the pathological tissues. Both drugs are inactive in the absence of light, presenting only few side effects. The incorporation of the two drugs into a SOPC bilayer -used as a model membrane- was studied by ATR-FTIR. An original approach was applied, involving lyotropic transitions and a very slow dehydration rate of the sample. In low water content and dry film, Temoporfin highly affects stretching vibrations of SOPC chains and polar groups, showing that Temoporfin is inserted into the bilayer in both apolar and polar regions. In fully hydrated layers, Temoporfin - SOPC interactions still take place but only impact Temoporfin vibration bands. Verteporfin shows smaller effect on both chain and polar groups' vibrations of SOPC, with the exception of choline group, suggesting that Verteporfin is inserted into the bilayer to a lesser extent and remains at the bilayer polar interface. These results can be used to better understand drugs behavior in biological media.

Pegylation – in search of balance and enhanced bioavailability

In the process of finding better therapeutics, thousands of new molecules are synthesised every day. Many of these can be poorly soluble in water, leading to a potentially promising drug being rejected during testing due to its poor solubility. Polyethylene glycol (PEG) has become known as an excellent modification to remedy this and was initially used to increase circulation time and reduce the immunogenicity of therapeutic proteins. Thus significantly increasing their safety and range of use. Another group of compounds in which significant benefits of pegylation have been seen are photosensitisers. Used in photodynamic therapy, they are often characterised by very high hydrophobicity. Pegylation of their structure significantly increases their affinity for cancer cells and facilitates their penetration through cell membranes. Classical small-molecule drugs can benefit from temporary combinations hydrolysed in the body or very short PEG chains. This approach allows a significant increase in the bioavailability of the drug while avoiding the disadvantages of small molecule pegylation. However, the most common motive for pegylation recently is the creation of drug carriers. Liposomes and nanoparticles make it possible to exploit the advantages of PEG to stabilise their structure and increase circulation time while not modifying the structure of the active compound. Unfortunately, PEGs also have their drawbacks. The first is their high molecular weight range, especially for longer chains, which poses difficulties in purification. Another is the emergence of antibodies directed against PEG. Nevertheless, pegylation is still an up-and-coming method for modifying pharmaceutically active molecules.

A mitochondria-anchored supramolecular photosensitizer as a pyroptosis inducer for potent photodynamic therapy and enhanced antitumor immunity

BACKGROUND

The discovery of a potent photosensitizer with desirable immunogenic cell death (ICD) ability can prominently enhance antitumor immunity in photodynamic therapy (PDT). However, majority of commercially-available photosensitizers suffer from serious aggregation and fail to elicit sufficient ICD. Pyroptosis as a newly identified pattern for potent ICD generation is rarely disclosed in reported photosensitizers. In addition, the photosensitizer with excellent mitochondria-anchored ability evokes prominent mitochondria oxidative stress, and consequently induces ICD.

RESULTS

Herein, a novel supramolecular photosensitizer LDH@ZnPc is reported, without complicated preparation, but reveals desirable pyroptosis-triggered ability with mitochondria anchoring feature. LDH@ZnPc is obtained through isolation of ZnPc using positive charged layered double hydroxides (LDH), and excellent mitochondria-anchored ability is achieved. More importantly, LDH@ZnPc-mediated PDT can effectively initiate gasdermin D (GSDMD)-dependent pyroptosis of tumor cells. In vitro and in vivo results verify robust ICD ability and potent tumor inhibition efficacy, and antitumor immunity towards distant tumor inhibition.

CONCLUSIONS

This study reveals that LDH@ZnPc can act as an excellent pyroptosis inducer with simultaneous mitochondria anchoring ability for enhancing photodynamic therapy and boosting antitumor immunity.

Spotlight on Photoactivatable Liposomes beyond Drug Delivery: An Enabler of Multitargeting of Molecular Pathways

The potential of photoactivating certain molecules, photosensitizers (PS), resulting in photochemical processes, has long been realized in the form of photodynamic therapy (PDT) for the management of several cancerous and noncancerous pathologies. With an improved understanding of the photoactivation process and its broader implications, efforts are being made to exploit the various facets of photoactivation, PDT, and the associated phenomenon of photodynamic priming in enhancing treatment outcomes, specifically in cancer therapeutics. The parallel emergence of nanomedicine, specifically liposome-based nanoformulations, and the convergence of the two fields of liposome-based drug delivery and PDT have led to the development of unique hybrid systems, which combine the exciting features of liposomes with adequate complementation through the photoactivation process. While initially liposomes carrying photosensitizers (PSs) were developed for enhancing the pharmacokinetics and the general applicability of PSs, more recently, PS-loaded liposomes, apart from their utility in PDT, have found several applications including enhanced targeting of drugs, coloading multiple therapeutic agents to enhance synergistic effects, imaging, priming, triggering drug release, and facilitating the escape of therapeutic agents from the endolysosomal complex. This review discusses the design strategies, potential, and unique attributes of these hybrid systems, with not only photoactivation as an attribute but also the ability to encapsulate multiple agents for imaging, biomodulation, priming, and therapy referred to as photoactivatable multiagent/inhibitor liposomes (PMILS) and their targeted versions─targeted PMILS (TPMILS). While liposomes have formed their own niche in nanotechnology and nanomedicine with several clinically approved formulations, we try to highlight how using PS-loaded liposomes could address some of the limitations and concerns usually associated with liposomes to overcome them and enhance their preclinical and clinical utility in the future.

Nanoemulsion applications in photodynamic therapy

Nanoemulsion, or nanoscaled-size emulsions, is a thermodynamically stable system formed by blending two immiscible liquids, blended with an emulsifying agent to produce a single phase. Nanoemulsion science has advanced rapidly in recent years, and it has opened up new opportunities in a variety of fields, including pharmaceuticals, biotechnology, food, and cosmetics. Nanoemulsion has been recognized as a potential drug delivery technology for various drugs, such as photosensitizing agents (PS). In photodynamic therapy (PDT), PSs produce cytotoxic reactive oxygen species under specific light irradiation, which oxidize the surrounding tissues. Over the past decades, the idea of PS-loaded nanoemulsions has received researchers' attention due to their ability to overcome several limitations of common PSs, such as limited permeability, non-specific phototoxicity, hydrophobicity, low bioavailability, and self-aggregation tendency. This review aims to provide fundamental knowledge of nanoemulsion formulations and the principles of PDT. It also discusses nanoemulsion-based PDT strategies and examines nanoemulsion advantages for PDT, highlighting future possibilities for nanoemulsion use.

MMP-2 Inhibitor-Mediated Tumor Microenvironment Regulation Using a Sequentially Released Bio-Nanosystem for Enhanced Cancer Photo-Immunotherapy

Combining photodynamic therapy (PDT) with natural killer (NK) cell-based immunotherapy has shown great potential against cancers, but the shedding of NK group 2, member D ligands (NKG2DLs) on tumor cells inhibited NK cell activation in the tumor microenvironment. Herein, we assembled microenvironment-/light-responsive bio-nanosystems (MLRNs) consisting of SB-3CT-containing β-cyclodextrins (β-CDs) and photosensitizer-loaded liposomes, in which SB-3CT was considered to remodel the tumor microenvironment. β-CDs and liposomes were linked by metalloproteinase 2 (MMP-2) responsive peptides, enabling sequential release of SB-3CT and chlorin e6 triggered by the MMP-2-abundant tumor microenvironment and 660 nm laser irradiation, respectively. Released SB-3CT blocked tumor immune escape by antagonizing MMP-2 and promoting the NKG2D/NKG2DL pathway, while liposomes were taken up by tumor cells for PDT. MLRN-mediated photo-immunotherapy significantly induced melanoma cell cytotoxicity (83.31%), inhibited tumor growth (relative tumor proliferation rate: 1.13% of that of normal saline) in the xenografted tumor model, and enhanced tumor-infiltrating NK cell (148 times) and NKG2DL expression (9.55 and 16.52 times for MICA and ULBP-1, respectively), achieving a synergistic effect. This study not only provided a simple insight into the development of new nanomedicine for programed release of antitumor drugs and better integration of PDT and immunotherapy but also a novel modality for clinical NK cell-mediated immunotherapy against melanoma.

Advances in nanomaterials for the diagnosis and treatment of head and neck cancers: A review

Nanomaterials (NMs) have increasingly been used for the diagnosis and treatment of head and neck cancers (HNCs) over the past decade. HNCs can easily infiltrate surrounding tissues and form distant metastases, meaning that most patients with HNC are diagnosed at an advanced stage and often have a poor prognosis. Since NMs can be used to deliver various agents, including imaging agents, drugs, genes, vaccines, radiosensitisers, and photosensitisers, they play a crucial role in the development of novel technologies for the diagnosis and treatment of HNCs. Indeed, NMs have been reported to enhance delivery efficiency and improve the prognosis of patients with HNC by allowing targeted delivery, controlled release, responses to stimuli, and the delivery of multiple agents. In this review, we consider recent advances in NMs that could be used to improve the diagnosis, treatment, and prognosis of patients with HNC and the potential for future research.

Zinc(II), Palladium(II), and Metal-Free Phthalocyanines Bearing Nipagin-Functionalized Substituents against Candida auris and Selected Multidrug-Resistant Microbes

Due to the rapidly increasing problem of antibiotic resistance in recent years, the use of phthalocyanines as photosensitizers with their superior properties in photodynamic antimicrobial therapy (PACT) applications has become important. In this study, magnesium(II) 1,4,8,11,15,18,22,25-octakis(4-[4-butoxycarbonylphenoxy]butyloxy)phthalocyanine was used in the demetalation reaction in trifluoroacetic acid, and subsequently subjected to metalation reaction in dimethylformamide with zinc(II) acetate and bis(benzonitrile)palladium(II) chloride towards zinc(II) and palladium(II) derivatives. Three phthalocyanines, including a demetalated one as well as two metalated, in the core with zinc(II) and palladium(II) were characterized using 1D and 2D NMR spectroscopy and mass spectrometry. In addition, all macrocycles were subjected to absorption and emission studies as well as photostability tests. In a photochemical study, zinc(II) and palladium(II) phthalocyanine complexes appeared to be efficient singlet oxygen generators. There were noted quantum yields of singlet oxygen generation for zinc(II) phthalocyanine derivative in DMF and DMSO at 0.55 and 0.72, whereas for palladium(II) complex at 0.73 and 0.77, respectively. Liposomal formulations of phthalocyanine derivatives were prepared, and their activity was evaluated against a broad spectrum of antibiotic-resistant microorganisms, such as methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli (ESBL+), Candida albicans resistant to fluconazole, C. auris, and against dermatophytes. Phthalocyanine palladium(II) complex showed the highest bactericidal activity against all antibiotic-resistant microorganisms, including reducing C. auris growth at 3.54 log.

Multifunctional Nanoplatforms as a Novel Effective Approach in Photodynamic Therapy and Chemotherapy, to Overcome Multidrug Resistance in Cancer

It is more than sixty years since the era of modern photodynamic therapy (PDT) for cancer began. Enhanced selectivity for malignant cells with a reduced selectivity for non-malignant cells and good biocompatibility along with the limited occurrence of side effects are considered to be the most significant advantages of PDT in comparison with conventional therapeutic approaches, e.g., chemotherapy. The phenomenon of multidrug resistance, which is associated with drug efflux transporters, was originally identified in relation to the application of chemotherapy. Unfortunately, over the last thirty years, numerous papers have shown that many photosensitizers are the substrates of efflux transporters, significantly restricting the effectiveness of PDT. The concept of a dynamic nanoplatform offers a possible solution to minimize the multidrug resistance effect in cells affected by PDT. Indeed, recent findings have shown that the utilization of nanoparticles could significantly enhance the therapeutic efficacy of PDT. Additionally, multifunctional nanoplatforms could induce the synergistic effect of combined treatment regimens, such as PDT with chemotherapy. Moreover, the surface modifications that are associated with nanoparticle functionalization significantly improve the target potential of PDT or chemo-PDT in multidrug resistant and cancer stem cells.

Single-treatment tumor ablation with photodynamic liposomal irinotecan sucrosulfate

Irinotecan (IRI) loaded actively into PEGylated liposomes via a sucrosulfate gradient has been approved recently to treat advanced pancreatic cancer. In this study, a similar liposomal composition was developed that includes a low mole fraction (1 mol.%) of porphyrin-phospholipid (PoP), a photosensitizer that stably incorporates into liposomes, to confer light-triggered IRI release. IRI-loaded PoP liposomes containing ammonium sucrosulfate (ASOS) as a complexing agent were more stable in serum compared to liposomes employing the more conventional ammonium sulfate. Without irradiation, PoP IRI liposomes released less than 5% IRI during 8 h of incubation in bovine serum at 37 °C, but released over 90% of the drug within minutes of exposure to red light (665 nm) irradiation. A single treatment with IRI-PoP liposomes and light exposure (15 mg/kg IRI with 250 J/cm2) resulted in tumor eradication in mice bearing either MIA PaCa-2 tumors or low-passage patient-derived tumor xenografts that recapitulate characteristics of the clinical disease. Analogous monotherapies of IRI or photodynamic therapy were ineffective in controlling tumor growth. Enhanced drug uptake could be visualized within laser-treated tumors by direct in situ imaging of irinotecan. Biodistribution analysis of IRI, its active metabolite (SN-38), and major metabolite (SN-38 G) showed that laser treatment significantly increased tumor accumulation of all IRI-derived molecular species. A pharmacokinetic model that hypothesized tumor vasculature permeabilization as the primary reason underlying the increased drug deposition accounted for the enhanced drug influx into tumors.

Nanomaterials enabling clinical translation of antimicrobial photodynamic therapy

Antimicrobial photodynamic therapy (aPDT) has emerged as a promising approach to aid the fight against looming antibiotic resistance. aPDT harnesses the energy of light through photosenstizers to generate highly reactive oxygen species that can inactivate bacteria and fungi with no resistance. To date aPDT has shown great efficacy against microbes causing localized infections in the skin and the oral cavity. However, its wide application in clinical settings has been limited due to both physicochemical and biological challenges. Over the past decade nanomaterials have contributed to promoting photosensitizer performance and aPDT efficiency, yet further developments are required to establish accredited treatment options. In this review we discuss the challenges facing the clinical application of aPDT and the opportunities that nanotechnology may offer to promote the safety and efficiency of aPDT.

New Cysteine-Containing PEG-Glycerolipid Increases the Bloodstream Circulation Time of Upconverting Nanoparticles

Upconverting nanoparticles have unique spectral and photophysical properties that make them suitable for development of theranostics for imaging and treating large and deep-seated tumors. Nanoparticles based on NaYF₄ crystals doped with lanthanides Yb³⁺ and Er³⁺ were obtained by the high-temperature decomposition of trifluoroacetates in oleic acid and 1-octadecene. Such particles have pronounced hydrophobic properties. Therefore, to obtain stable dispersions in aqueous media for the study of their properties in vivo and in vitro, the polyethylene glycol (PEG)-glycerolipids of various structures were obtained. To increase the circulation time of PEG-lipid coated nanoparticles in the bloodstream, long-chain substituents are needed to be attached to the glycerol backbone using ether bonds. To prevent nanoparticle aggregation, an L-cysteine-derived negatively charged carboxy group should be included in the lipid molecule.

Recent Advances in Near Infrared Upconverting Nanomaterials for Targeted Photodynamic Therapy of Cancer

Photodynamic therapy (PDT) is a well-established treatment of cancer that uses the toxic reactive oxygen species, including singlet oxygen (1O2), generated by photosensitiser drugs following irradiation of a specific wavelength to destroy the cancerous cells and tumours. Visible light is commonly used as the excitation source in PDT, which is not ideal for cancer treatment due to its reduced tissue penetration, and thus inefficiency to treat deep-lying tumours. Additionally, these wavelengths exhibit elevated autofluorescence background from the biological tissues which hinders optical biomedical imaging. An alternative to UV-Vis irradiation is the use of near infrared (NIR) excitation for PDT. This can be achieved using upconverting nanoparticles (UCNPs) functionalised with photosensitiser (PS) drugs where UCNPs can be used as an indirect excitation source for the activation of PS drugs yielding to the production of singlet 1O2 following NIR excitation. The use of nanoparticles for PDT is also beneficial due to their tumour targeting capability, either passively via the enhanced permeability and retention (EPR) effect or actively via stimuli-responsive targeting and ligand-mediated targeting (ie. using recognition units that can bind specific receptors only present or overexpressed on tumour cells). Here, we review recent advances in NIR upconverting nanomaterials for PDT of cancer with a clear distinction between those reported nanoparticles that could potentially target the tumour due to accumulation via the EPR effect (passive targeting) and nanoparticle-based systems that contain targeting agents with the aim of actively target the tumour via a molecular recognition process.

Antibody-conjugated liposomes loaded with indocyanine green for oral targeted photoacoustic imaging-guided sonodynamic therapy of Helicobacter pylori infection

Helicobacter pylori is a causative factor of various gastrointestinal tract diseases. As clinical antibiotic-based therapy for H. pylori infection might induce bacterial drug resistance, the in vivo eradication of H. pylori remains a huge challenge. In the present study, monoclonal antibody-conjugated liposomes loaded with indocyanine green (ICG) (HpAb-LiP-ICG) were successfully developed for targeted photoacoustic (PA) imaging-guided sonodynamic therapy (SDT) of H. pylori infection in vivo. HpAb-LiP-ICG showed high stability and favorable biocompatibility in acidic environment (pH 1.5) and was used for treating H. pylori-infected mice through oral administration. PA imaging showed that HpAb-LiP-ICG could precisely recognize and target H. pylori in the stomach. Following the targeting of HpAb-LiP-ICG to H. pylori, ICG was activated to generate singlet oxygen (¹O₂) for eliminating H. pylori under ultrasound (US) irradiation. Pathological analysis revealed that the HpAb-LiP-ICG-mediated SDT eradicated H. pylori without unintended toxicity to normal tissues. In conclusion, the HpAb-LiP-ICG-mediated SDT might shed new light on treating H. pylori infection, indicating the clinical translational prospects of this therapy in near future. STATEMENT OF SIGNIFICANCE: Traditional antibiotic-based therapy for Helicobacter pylori infections suffers from the risk of drug resistance. To meet this challenge, a monoclonal antibody-conjugated nanoliposome loaded with indocyanine green (ICG) (HpAb-LiP-ICG) was successfully developed, and efficient eradication of H. pylori was achieved in vivo by visual sonodynamic therapy (SDT). HpAb-LiP-ICG exhibited biocompatibility, targeting, and stability in the acidic microenvironment. Under ultrasound (US) irradiation in vitro, the HpAb-LiP-ICG nanoliposomes accumulated on the surface of H. pylori were activated to produce adequate singlet oxygen (¹O₂) to eliminate H. pylori. Gastric mucous tissues infected with H. pylori recovered to the normal state after HpAb-LiP-ICG-mediated SDT without side effects, thus highlighting the clinical translational prospects of the prepared HpAb-LiP-ICG nanoliposome in near future.

Nanomaterials-based photosensitizers and delivery systems for photodynamic cancer therapy

The increasing cancer morbidity and mortality requires the development of high-efficiency and low-toxicity anticancer approaches. In recent years, photodynamic therapy (PDT) has attracted much attention in cancer therapy due to its non-invasive features and low side effects. Photosensitizer (PS) is one of the key factors of PDT, and its successful delivery largely determines the outcome of PDT. Although a few PS molecules have been approved for clinical use, PDT is still limited by the low stability and poor tumor targeting capacity of PSs. Various nanomaterial systems have shown great potentials in improving PDT, such as metal nanoparticles, graphene-based nanomaterials, liposomes, ROS-sensitive nanocarriers and supramolecular nanomaterials. The small molecular PSs can be loaded in functional nanomaterials to enhance the PS stability and tumor targeted delivery, and some functionalized nanomaterials themselves can be directly used as PSs. Herein, we aim to provide a comprehensive understanding of PDT, and summarize the recent progress of nanomaterials-based PSs and delivery systems in anticancer PDT. In addition, the concerns of nanomaterials-based PDT including low tumor targeting capacity, limited light penetration, hypoxia and nonspecific protein corona formation are discussed. The possible solutions to these concerns are also discussed.

Dimensional Reduction Enhances Photodynamic Therapy of Metal-Organic Nanophotosensitizers

Herein we report that dimensional reduction from three-dimensional nanoscale metal-organic frameworks (nMOFs) to two-dimensional nanoscale metal-organic layers (nMOLs) increases the frequency of encounters between photosensitizers and oxygen and facilitates the diffusion of singlet oxygen from the nMOL to significantly enhance photodynamic therapy. The nMOFs and nMOLs share the same M12-oxo (M = Zr, Hf) secondary building units and 5,15-di-p-benzoatoporphyrin (DBP) ligands but exhibit three-dimensional and two-dimensional topologies, respectively. Molecular dynamics simulations and experimental studies revealed that the nMOLs with a monolayer morphology enhanced the generation of reactive oxygen species and exhibited over an order of magnitude higher cytotoxicity over the nMOFs. In a mouse model of triple-negative breast cancer, Hf-DBP nMOL showed 49.1% more tumor inhibition, an 80% higher cure rate, and 16.3-fold lower metastasis potential than Hf-DBP nMOF.

Advances in Photodynamic Therapy Based on Nanotechnology and Its Application in Skin Cancer

Comprehensive cancer treatments have been widely studied. Traditional treatment methods (e.g., radiotherapy, chemotherapy), despite ablating tumors, inevitably damage normal cells and cause serious complications. Photodynamic therapy (PDT), with its low rate of trauma, accurate targeting, synergism, repeatability, has displayed great advantages in the treatment of tumors. In recent years, nanotech-based PDT has provided a new modality for cancer treatment. Direct modification of PSs by nanotechnology or the delivery of PSs by nanocarriers can improve their targeting, specificity, and PDT efficacy for tumors. In this review, we strive to provide the reader with a comprehensive overview, on various aspects of the types, characteristics, and research progress of photosensitizers and nanomaterials used in PDT. And the application progress and relative limitations of nanotech-PDT in non-melanoma skin cancer and melanoma are also summarized.

Photophysics of tetracarboxy-zinc phthalocyanine photosensitizers

A ZnPc(COOH)4/Fe3O4/Ch photosensitizer was synthesized by immobilization of ZnPc(COOH)4 onto Fe3O4/chitosan nanoparticles by a simple immersion method.

Biocompatible Nanocarriers for Enhanced Cancer Photodynamic Therapy Applications

In recent years, the role of nanotechnology in drug delivery has become increasingly important, and this field of research holds many potential benefits for cancer treatment, particularly, in achieving cancer cell targeting and reducing the side effects of anticancer drugs. Biocompatible and biodegradable properties have been essential for using a novel material as a carrier molecule in drug delivery applications. Biocompatible nanocarriers are easy to synthesize, and their surface chemistry often enables them to load different types of photosensitizers (PS) to use targeted photodynamic therapy (PDT) for cancer treatment. This review article explores recent studies on the use of different biocompatible nanocarriers, their potential applications in PDT, including PS-loaded biocompatible nanocarriers, and the effective targeting therapy of PS-loaded biocompatible nanocarriers in PDT for cancer treatment. Furthermore, the review briefly recaps the global clinical trials of PDT and its applications in cancer treatment.

Self-Remedied Nanomedicine for Surmounting the Achilles' Heel of Photodynamic Tumor Therapy

Oxygen-dependent photodynamic therapy (PDT) could exacerbate tumor hypoxia to induce the upregulation of hypoxia-inducible factor-1α (HIF-1α), which would promote tumor growth and metastasis. In this paper, a self-remedied nanomedicine is developed based on a photosensitizer and a HIF-1α inhibitor to surmount the Achilles' heel of PDT for enhanced antitumor efficacy. Specifically, the nanomedicine (designated as CYC-1) is prepared by the self-assembly of chlorine e6 (Ce6) and 3-(5'-hydroxy-methyl-2'-furyl)-1-benzylindazole (YC-1) through π-π stacking and hydrophobic interactions. Of special note, carrier-free CYC-1 holds an extremely high drug loading rate and avoids excipient-triggered adverse reactions. Intravenously administered CYC-1 prefers to accumulate in the tumor tissue for effective cellular uptake. More importantly, it is verified that CYC-1 is capable of inhibiting the HIF-1α activity, thereby improving its PDT efficacy on tumor suppression. Besides, CYC-1 has the overwhelming superiority in restraining tumor proliferation over the combined administration of Ce6 and YC-1, which highlights the advantage of this self-remedied strategy in drug delivery and tumor therapy. This study sheds light on the development of self-delivery nanomedicine for efficient PDT against malignancies.