In vitro and in vivo activities of verteporfin-loaded nanoparticles

Self-delivery nanodrug to manipulate tumor microenvironment for boosting photodynamic cancer immunotherapy

Immunotherapy has captured attention for its high clinical efficacy. However, its efficacy is limited by inadequate immune activation. Therefore, a platform to activate the immune system and amplify the host's immune response against tumors is urgently needed. Herein, a self-delivery photodynamic nanodrug (VAC@HSA) is reported as inducing immunogenic cell death (ICD), promoting the recruitment of dendritic cells (DCs), and normalizing tumor blood vessels. Firstly, verteporfin with laser assistance releases tumor-associated antigen to induce ICD, while celecoxib downregulates prostaglandin E2 and releases CCL5 to activate DC recruitment. Moreover, vasculature is normalized through axitinib, which contributes to reducing tumor hypoxia and reversing the immunosuppressive effects of vascular endothelial growth factor. This joint action promotes the infiltration of immune effector cells into the tumor. Therefore, the amplified photodynamic nanodrug with excellent biocompatibility effectively inhibits tumor growth and lung metastasis and produces a cascade of immune responses. Our study demonstrates a practically innovative strategy for activating cancer immunotherapy, which can alter the "cold" properties of tumors.

Age-Related Macular Degeneration - Therapies and Their Delivery

Age-related macular degeneration (ARMD) is a degenerative ocular disease that is the most important cause of irreversible vision loss in old-aged people in developed countries. Around fifty percent of vision impairments in developed countries are due to ARMD. It is a multifaceted disease that is associated with both genetic and environmental risk factors. The most important treatments option for ARMD includes laser photocoagulation, photodynamic therapy (PDT), Anti-VEGF Injections, and combination therapies. In this review, we also propose that topical ocular drug delivery with nanocarriers has more attention for the treatment of ARMD. The nanocarriers were specially designed for enhanced corneal residential time, prolonged drug release and action, and minimizing the frequency of administrations. Different types of nanocarriers were developed for the topical ocular delivery system, such as nanomicelles, nanoemulsions, nanosuspensions, liposomes, and polymeric nanoparticles. These topical ocular nanocarriers were administered topically, and they can fix the hydrophobic substances, increase solubility and improve the bioavailability of an administered drug. Hence the topical ocular delivery systems with nanocarriers provide a safe and effective therapeutic strategy and promising tool for the treatment of posterior segment ocular diseases ARMD.

Photoactive Parietin-loaded nanocarriers as an efficient therapeutic platform against triple-negative breast cancer

The application of photodynamic therapy has become more and more important in combating cancer. However, the high lipophilic nature of most photosensitizers limits their parenteral administration and leads to aggregation in the biological environment. To resolve this problem and deliver a photoactive form, the natural photosensitizer parietin (PTN) was encapsulated in poly(lactic-co-glycolic acid) nanoparticles (PTN NPs) by emulsification diffusion method. PTN NPs displayed a size of 193.70 nm and 157.31 nm, characterized by dynamic light scattering and atomic force microscopy, respectively. As the photoactivity of parietin is essential for therapy, the quantum yield of PTN NPs and the in vitro release were assessed. The antiproliferative activity, the intracellular generation of reactive oxygen species, mitochondrial potential depolarization, and lysosomal membrane permeabilization were evaluated in triple-negative breast cancer cells (MDA-MB-231 cells). At the same time, confocal laser scanning microscopy (CLSM) and flow cytometry were used to investigate the cellular uptake profile. In addition, the chorioallantoic membrane (CAM) was employed to evaluate the antiangiogenic effect microscopically. The spherical monomodal PTN NPs show a quantum yield of 0.4. The biological assessment on MDA-MB-231 cells revealed that free PTN and PTN NPs inhibited cell proliferation with IC50 of 0.95 µM and 1.9 µM at 6 J/cm2, respectively, and this can be attributed to the intracellular uptake profile as proved by flow cytometry. Eventually, the CAM study illustrated that PTN NPs could reduce the number of angiogenic blood vessels and disrupt the vitality of xenografted tumors. In conclusion, PTN NPs are a promising anticancer strategy in vitro and might be a tool for fighting cancer in vivo.

Nanotherapeutic Intervention in Photodynamic Therapy for Cancer

The clinical need for photodynamic therapy (PDT) has been growing for several decades. Notably, PDT is often used in oncology to treat a variety of tumors since it is a low-risk therapy with excellent selectivity, does not conflict with other therapies, and may be repeated as necessary. The mechanism of action of PDT is the photoactivation of a particular photosensitizer (PS) in a tumor microenvironment in the presence of oxygen. During PDT, cancer cells produce singlet oxygen (¹O₂) and reactive oxygen species (ROS) upon activation of PSs by irradiation, which efficiently kills the tumor. However, PDT's effectiveness in curing a deep-seated malignancy is constrained by three key reasons: a tumor's inadequate PS accumulation in tumor tissues, a hypoxic core with low oxygen content in solid tumors, and limited depth of light penetration. PDTs are therefore restricted to the management of thin and superficial cancers. With the development of nanotechnology, PDT's ability to penetrate deep tumor tissues and exert desired therapeutic effects has become a reality. However, further advancement in this field of research is necessary to address the challenges with PDT and ameliorate the therapeutic outcome. This review presents an overview of PSs, the mechanism of loading of PSs, nanomedicine-based solutions for enhancing PDT, and their biological applications including chemodynamic therapy, chemo-photodynamic therapy, PDT-electroporation, photodynamic-photothermal (PDT-PTT) therapy, and PDT-immunotherapy. Furthermore, the review discusses the mechanism of ROS generation in PDT advantages and challenges of PSs in PDT.

Reaction mechanism of nanomedicine based on porphyrin skeleton and its application prospects

Research on porphyrin-based photosensitizing drugs is becoming increasingly popular. They possess unique diagnostic capabilities and therapeutic effects that have gained wide recognition in oncology drug development. In recent years, the rapid growth of nanotechnology has brought great hope for nanopharmaceutical formulations. By combining porphyrins with various nanomaterials, people have improved the properties of porphyrin compounds, making drug delivery easier. Porphyrin-based nanoparticles can enhance the effect of photodynamic therapy for cancer treatment, providing opportunities for achieving complex targeting strategies and versatility with promising applications in drug carriers, tumor imaging, and treatment. This paper reviews recent porphyrin nanodrugs, including inorganic-organic hybrid nanoparticles, nanomicelles, self-assembled nanoparticles, and combination therapeutic nanodrugs, and their actions and effects on cancer cells when performing photodynamic therapy. It also discusses the drawbacks as well as the prospects for development.

Advanced techniques for performing photodynamic therapy in deep-seated tissues

Photodynamic therapy (PDT) is a promising localized cancer treatment modality. It has been used successfully to treat a range of dermatological conditions with comparable efficacy to conventional treatments. However, some drawbacks limit the clinical utility of PDT in treating deep-seated tumors. Notably, the penetration limitation of UV and visible light, commonly applied to activate photosensitizers, makes PDT incompetent in treating deep-seated tumors. Development in light delivery technologies, especially fiber optics, led to improved clinical strategies for accessing deep tissues for irradiation. However, PDT efficacy issues remained partly due to light penetration limitations. In this review, we first summarized the current PDT applications for deep-seated tumor treatment. Then, the most recent progress in advanced techniques to overcome the light penetration limitation in PDT, including using functional nanomaterials that can either self-illuminate or be activated by near-infrared (NIR) light and X-rays as transducers, and implantable light delivery devices were discussed. Finally, current challenges and future opportunities of these technologies were discussed, which we hope may inspire the development of more effective techniques to enhance PDT efficacy against deep-seated tumors.

Sustained Drug Release from Smart Nanoparticles in Cancer Therapy: A Comprehensive Review

Although nanomedicine has been highly investigated for cancer treatment over the past decades, only a few nanomedicines are currently approved and in the market; making this field poorly represented in clinical applications. Key research gaps that require optimization to successfully translate the use of nanomedicines have been identified, but not addressed; among these, the lack of control of the release pattern of therapeutics is the most important. To solve these issues with currently used nanomedicines (e.g., burst release, systemic release), different strategies for the design and manufacturing of nanomedicines allowing for better control over the therapeutic release, are currently being investigated. The inclusion of stimuli-responsive properties and prolonged drug release have been identified as effective approaches to include in nanomedicine, and are discussed in this paper. Recently, smart sustained release nanoparticles have been successfully designed to safely and efficiently deliver therapeutics with different kinetic profiles, making them promising for many drug delivery applications and in specific for cancer treatment. In this review, the state-of-the-art of smart sustained release nanoparticles is discussed, focusing on the design strategies and performances of polymeric nanotechnologies. A complete list of nanomedicines currently tested in clinical trials and approved nanomedicines for cancer treatment is presented, critically discussing advantages and limitations with respect to the newly developed nanotechnologies and manufacturing methods. By the presented discussion and the highlight of nanomedicine design criteria and current limitations, this review paper could be of high interest to identify key features for the design of release-controlled nanomedicine for cancer treatment.

Biological Evaluation of Photodynamic Effect Mediated by Nanoparticles with Embedded Porphyrin Photosensitizer

Clinically approved photodynamic therapy (PDT) is a minimally invasive treatment procedure that uses three key components: photosensitization, a light source, and tissue oxygen. However, the photodynamic effect is limited by both the photophysical properties of photosensitizers as well as their low selectivity, leading to damage to adjacent normal tissue and/or inadequate biodistribution. Nanoparticles (NPs) represent a new option for PDT that can overcome most of the limitations of conventional photosensitizers and can also promote photosensitizer accumulation in target cells through enhanced permeation and retention effects. In this in vitro study, the photodynamic effect of TPP photosensitizers embedded in polystyrene nanoparticles was observed on the non-tumor NIH3T3 cell line and HeLa and G361 tumor cell lines. The efficacy was evaluated by viability assay, while reactive oxygen species production, changes in membrane mitochondrial potential, and morphological changes before and after treatment were imaged by atomic force microscopy. The tested nanoparticles with embedded TPP were found to become cytotoxic only after activation by blue light (414 nm) due to the production of reactive oxygen species. The photodynamic effect observed in this evaluation was significantly higher in both tumor lines than the effect observed in the non-tumor line, and the resulting phototoxicity depended on the concentration of photosensitizer and irradiation time.

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.

Insights on the polypyrrole based nanoformulations for photodynamic therapy

This review is written to endow updated information on polypyrrole based photosensitizers for the treatment of deadly diseases such as cancer and microbial infection. Tetrapyrrolic macromolecules such as porphyrins and phthalocyanines hold unique photophysical properties which make them very useful compounds for various biomedical applications. Besides their properties, they also have some limitations such as low water solubility, bioavailability, biocompatibility and lack of specificity, etc. Researchers are trying to overcome these limitations by incorporating photosensitizers into the different types of nanoparticles and improve the quality of photodynamic therapy. We have contributed to this field by synthesizing and developing polypyrrolic photosensitizer based nanoparticles for potential applications in antimicrobial and anticancer photodynamic activity. Throughout this review, newly synthesized and existing PSs conjugated/encapsulated/doped/incorporated with nanoparticles are emphasized, which are essential for current and future research themes. Also in this review, we briefly summarized the research work carried over the past few years by considering the porphyrin based photosensitizers as alternative therapeutic entities for the treatment of microbial infections, cancers, and many other diseases.

Oxygen-Carrying Polymer Nanoconstructs for Radiodynamic Therapy of Deep Hypoxic Malignant Tumors

Radiodynamic therapy (RDT) is an emerging non-invasive anti-cancer treatment based on the generation of the reactive oxygen species (ROS) at the lesion site following the interaction between X-rays and a photosensitizer drug (PS). The broader application of RDT is impeded by the tumor-associated hypoxia that results in low availability of oxygen for the generation of sufficient amounts of ROS. Herein, a novel nanoparticle drug formulation for RDT, which addresses the problem of low oxygen availability, is reported. It consists of poly (lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) co-loaded with a PS drug verteporfin (VP), and the clinically approved oxygen-carrying molecule, perfluorooctylbromide (PFOB). When triggered by X-rays (4 Gy), under both normoxic and hypoxic conditions, PLGA-VP-PFOB nanoconstructs (NCs) induced a significant increase of the ROS production compared with matching PLGA-VP nanoparticles. The RDT with NCs effectively killed ~60% of human pancreatic cancer cells in monolayer cultures, and almost completely suppressed the outgrowth of tumor cells in 2-weeks clonogenic assay. In a 3D engineered model of pancreatic cancer metastasis to the liver, RDT with NCs destroyed ~35% of tumor cells, demonstrating an exceptional efficiency at a tissue level. These results show that PLGA-VP-PFOB is a promising agent for RDT of deep-seated hypoxic tumors.

Nanocarriers in photodynamic therapy-in vitro and in vivo studies

Photodynamic therapy (PDT) is a minimally invasive technique which has proven to be successful in the treatment of several types of tumors. This relatively simple method exploits three inseparable elements: phototoxic compound (photosensitizer [PS]), light source, and oxygen. Upon irradiation by light with specified wavelength, PS generates reactive oxygen species, which starts the cascade of reactions leading to cell death. The positive therapeutic outcome of PDT may be limited due to several aspects, including low water solubility of PSs, hampering their effective administration and blood circulation, as well as low tumor specificity, inefficient cellular uptake and activation energies requiring prolonged illumination times. One of the promising approaches to overcome these obstacles involves the use of carrier systems modulating pharmacokinetics and pharmacodynamics of the PSs. In the present review, we summarized current in vitro and in vivo studies regarding the use of nanoparticles as potential delivery devices for PSs to enhance their cellular uptake and cytotoxic properties, and thus-the therapeutic outcome of PDT. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Recent advances in photodynamic therapy for cancer and infectious diseases

Photodynamic therapy (PDT) is a treatment by combining light and a photosensitizer to generate reactive oxygen species (ROS) for cellular damage, and is used to treat cancer and infectious diseases. In this review, we focus on recent advances in design of new photosensitizers for increased production of ROS and in genetic engineering of biological photosensitizers to study cellular signaling pathways. A new concept has been proposed that PDT-induced acute inflammation can mediate neutrophil infiltration to deliver therapeutics in deep tumor tissues. Combination of PDT and immunotherapies (neutrophil-mediated therapeutic delivery) has shown the promising translation of PDT for cancer therapies. Furthermore, a new area in PDT is to treat bacterial infections to overcome the antimicrobial resistance. Finally, we have discussed the new directions of PDT for therapies of cancer and infectious diseases. In summary, we believe that rational design and innovations in nanomaterials may have a great impact on translation of PDT in cancer and infectious diseases. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

Recent advances in photodynamic therapy for cancer and infectious diseases

Photodynamic therapy (PDT) is a treatment by combining light and a photosensitizer to generate reactive oxygen species (ROS) for cellular damage, and is used to treat cancer and infectious diseases. In this review, we focus on recent advances in design of new photosensitizers for increased production of ROS and in genetic engineering of biological photosensitizers to study cellular signaling pathways. A new concept has been proposed that PDT-induced acute inflammation can mediate neutrophil infiltration to deliver therapeutics in deep tumor tissues. Combination of PDT and immunotherapies (neutrophil-mediated therapeutic delivery) has shown the promising translation of PDT for cancer therapies. Furthermore, a new area in PDT is to treat bacterial infections to overcome the antimicrobial resistance. Finally, we have discussed the new directions of PDT for therapies of cancer and infectious diseases. In summary, we believe that rational design and innovations in nanomaterials may have a great impact on translation of PDT in cancer and infectious diseases. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

Carbon dot-protoporphyrin IX conjugates for improved drug delivery and bioimaging

Photodynamic therapy (PDT) uses photosensitisers such as protoporphyrin IX (PpIX) to target tumours via the release of toxic singlet oxygen when irradiated. The effectivity of the treatment is limited by the innate properties of the photosensitizers; they typically exhibit inefficient accumulation in target tissue and high dark toxicity. Carbon dots (CDs) are biocompatible fluorescent nanoparticles which can improve PpIX cellular uptake and solubility. In this work, we present conjugates synthesised by host-guest encapsulation (PpIX@CD) and amide cross-linking (PpIX-CD). Characterization demonstrated conjugates have a loading efficiency of 34-48% and similar singlet oxygen production to PpIX. PpIX-containing CDs showed a 2.2 to 3.7-fold decrease in dark toxicity. PpIX-CD and PpIX@CD showed equivalent light-induced toxicity to PpIX in concentrations >1 μg/ml, leading to a 3.2 to 4.1-fold increase in photo-toxicity index (PI). The less soluble fraction of cross-linked conjugates (PpIX-CD)p did not show significant difference from PpIX. Confocal light scanning microscopy demonstrated rapid intracellular uptake and accumulation of conjugates. Our results demonstrate the variations between cross-linking strategies in CD-based conjugates, highlighting their potential as carriers in drug delivery and bioimaging applications.

The Physicochemical Properties of Graphene Nanocomposites Influence the Anticancer Effect

Graphene nanocomposite is an inorganic nanocomposite material, which has been widely used in the treatment of tumor at present due to its ability of drug loading, modifiability, photothermal effect, and photodynamic effect. However, the application of graphene nanocomposite is now limited due to the fact that the functions mentioned above are not well realized. This is mainly because people do not have a systematic understanding of the physical and chemical properties of GO nanomolecules, so that we cannot make full use of GO nanomolecules to make the most suitable materials for the use of medicine. Here, we are the first to discuss the influence of the physicochemical properties of graphene nanocomposite on the various functions related to their antitumor effects. The relationship between some important physicochemical properties of graphene nanocomposite such as diameter, shape, and surface chemistry and their functions related to antitumor effects was obtained through analysis, which provides evidence for the application of related materials in the future.

Core-matched nanoassemblies for targeted co-delivery of chemotherapy and photosensitizer to treat drug-resistant cancer

Emergence of drug resistance in tumors causes therapeutic failure or tumor relapse. Combination of chemotherapy and photodynamic therapy holds significant promise to treat drug-resistant tumors. However, stubborn hydrophobicity of photosensitizer (PS), low encapsulation efficiency and leaking problem of PS in organic carrier, and disparate physicochemical properties of PS and chemotherapeutics make the combination unachievable. Thus how to efficiently co-deliver the two functional agents to enable photo-chemotherapy seems to be one of the key challenges. Here, core-matched technology (CMT) was developed to realize efficient co-delivery of PS and chemotherapeutics, in which PS verteporfin (VP), tumor angiogenesis-targeting iNGR peptide and poly(lactic acid) (PLA) were respectively pre-modified with D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS), and the conjugates self-assembled into iNGR-modified and VP conjugated nanoassemblies (iNGR-VP-NA) with chemotherapeutic agent docetaxel (DTX) loaded in the hydrophobic core. The obtained iNGR-VP-NA-DTX was characterized by mean size of 166.0 ± 9.2 nm and morphology of uniformly spherical shape. In vitro, with the assistance of laser, iNGR-VP-NA-DTX exhibited higher cellular uptake, stronger cytotoxicity in HUVEC cells, drug-resistant HCT-15 tumor cells and more effective inhibition of tube formation than iNGR-VP-NA-DTX without laser or VP-NA-DTX with laser. After intravenously injected into mice, through the near-infrared light emitted by VP, iNGR-VP-NA exhibited improved accumulation compared to VP-NA in drug-resistant HCT-15 tumor. Besides, iNGR-VP-NA-DTX with laser enhanced inhibition of angiogenesis and induced severe apoptosis and necrosis in tumor tissues along with minimal impact to normal areas. These evidences demonstrated that iNGR-VP-NA-DTX was of great potential to treat drug-resistant tumors via efficient angiogenesis-targeted photo-chemotherapy. STATEMENT OF SIGNIFICANCE: Combination of chemotherapy and photodynamic therapy is thought to be a potential approach to treat drug-resistant cancer. However, it is difficult to realize optimized photo-chemotherapy in one nano-system. Here, iNGR-modified nanoassemblies is created based on core-matched nanotechnology to realize targeted photo-chemotherapy. In this study, the improved co-loading of chemotherapy and photosensitizer in the nanoassemblies exerted a synergistic anti-tumor effect and the decoration with iNGR enhanced tumor-targeting efficiency. In the presence of laser irradiation, the nanoassemblies exhibited enhanced and targeted anti-tumor efficacy in drug-resistant HCT-15 tumor both in vitro and in vivo.

Verteporfin-Loaded Poly(ethylene glycol)-Poly(beta-amino ester)-Poly(ethylene glycol) Triblock Micelles for Cancer Therapy

Amphiphilic polymers can be used to form micelles to deliver water-insoluble drugs. A biodegradable poly(ethylene glycol) (PEG)-poly(beta-amino ester) (PBAE)-PEG triblock copolymer was developed that is useful for drug delivery. It was shown to successfully encapsulate and pH-dependently release a water-insoluble, small molecule anticancer drug, verteporfin. PEG-PBAE-PEG micelle morphology was also controlled through variations to the hydrophobicity of the central PBAE block of the copolymer in order to evade macrophage uptake. Spherical micelles were 50 nm in diameter, while filamentous micelles were 31 nm in width with an average aspect ratio of 20. When delivered to RAW 264.7 mouse macrophages, filamentous micelles exhibited a 89% drop in cellular uptake percentage and a 5.6-fold drop in normalized geometric mean cellular uptake compared to spherical micelles. This demonstrates the potential of high-aspect-ratio, anisotropically shaped PEG-PBAE-PEG micelles to evade macrophage-mediated clearance. Both spherical and filamentous micelles also showed therapeutic efficacy in human triple-negative breast cancer and small cell lung cancer cells without requiring photodynamic therapy to achieve an anticancer effect. Both spherical and filamentous micelles were more effective in killing lung cancer cells than breast cancer cells at equivalent verteporfin concentrations, while spherical micelles were shown to be more effective than filamentous micelles against both cancer cells. Spherical and filamentous micelles at 5 and 10 μM respective verteporfin concentration resulted in 100% cell killing of lung cancer cells, but both micelles required a higher verteporfin concentration of 20 μM to kill breast cancer cells at the levels of 80% and 50% respectively. This work demonstrates the potential of PEG-PBAE-PEG as a biodegradable, anisotropic drug delivery system as well as the in vitro use of verteporfin-loaded micelles for cancer therapy.

Synergistic Targeting and Efficient Photodynamic Therapy Based on Graphene Oxide Quantum Dot-Upconversion Nanocrystal Hybrid Nanoparticles

Locating nanotherapeutics at the active sites, especially in the subcellular scale, is of great importance for nanoparticle-based photodynamic therapy (PDT) and other nanotherapies. However, subcellular targeting agents are generally nonspecific, despite the fact that the accumulation of a nanoformulation at active organelles leads to better therapeutic efficacy. A PDT nanoformulation is herein designed by using graphene oxide quantum dots (GOQDs) with rich functional groups as both the supporter for dual targeting modification and the photosensitizer for generating reactive oxygen species, and upconversion nanoparticles (UCNs) as the transducer of excitation light. A tumor-targeting agent, folic acid, and a mitochondrion-targeting moiety, carboxybutyl triphenylphosphonium, are simultaneously attached onto the UCNs-GOQDs hybrid nanoparticles by surface modification, and a synergistic targeting effect is obtained for these nanoparticles according to both in vitro and in vivo experiments. More significant cell death and a higher extent of mitochondrion damage are observed compared to the results of UCNs-GOQDs nanoparticles with no or just one targeting moiety. Furthermore, the PDT efficacy on tumor-bearing mice is also effectively improved. Overall, the current work presents a synergistic strategy to enhance subcellular targeting and the PDT efficacy for cancer therapy, which may also shed light on other kinds of nanotherapies.

Remotely Phototriggered, Transferrin-Targeted Polymeric Nanoparticles for the Treatment of Breast Cancer

Triple-negative breast cancer (TNBC) has the worst prognosis among all subtypes of breast cancer. Currently, no targeted treatment has been approved for TNBC. The goal of this study was to design a remotely triggered, targeted therapy for TNBC using polymeric nanoparticles and light. Active targeting of TNBC was achieved by conjugating the nanoparticles to a peptide (hTf) that binds to the transferrin receptor, which is overexpressed in TNBC. Photodynamic therapy (PDT) was explored for TNBC treatment by remotely triggering benzoporphyrin derivative monoacid (BPD), a photosensitizer, using near-infrared light. In this study, we investigated the use of actively targeting polymeric nanoparticles for PDT against TNBC using in vitro imaging and cytotoxicity studies. Fluorescence imaging confirmed that the BPD-loaded nanoparticles showed greater fluorescence in TNBC cells compared to free BPD, but more importantly, actively targeted nanoparticles displayed stronger fluorescence compared to passively targeted nanoparticles. Moreover, fluorescence imaging following competition with empty targeted nanoparticles validated the specificity of the targeted nanoparticles for TNBC cells. The PDT killing results were in line with the fluorescence imaging results, where actively targeting nanoparticles exhibited the highest phototriggered cytotoxicity in TNBC cells, making them an attractive nanoplatform for TNBC treatment.

Cancer nanomedicine: a review of recent success in drug delivery

Cancer continues to be one of the most difficult global healthcare problems. Although there is a large library of drugs that can be used in cancer treatment, the problem is selectively killing all the cancer cells while reducing collateral toxicity to healthy cells. There are several biological barriers to effective drug delivery in cancer such as renal, hepatic, or immune clearance. Nanoparticles loaded with drugs can be designed to overcome these biological barriers to improve efficacy while reducing morbidity. Nanomedicine has ushered in a new era for drug delivery by improving the therapeutic indices of the active pharmaceutical ingredients engineered within nanoparticles. First generation nanomedicines have received widespread clinical approval over the past two decades, from Doxil® (liposomal doxorubicin) in 1995 to Onivyde® (liposomal irinotecan) in 2015. This review highlights the biological barriers to effective drug delivery in cancer, emphasizing the need for nanoparticles for improving therapeutic outcomes. A summary of different nanoparticles used for drug delivery applications in cancer are presented. The review summarizes recent successes in cancer nanomedicine in the clinic. The clinical trials of Onivyde leading to its approval in 2015 by the Food and Drug Adminstration are highlighted as a case study in the recent clinical success of nanomedicine against cancer. Next generation nanomedicines need to be better targeted to specifically destroy cancerous tissue, but face several obstacles in their clinical development, including identification of appropriate biomarkers to target, scale-up of synthesis, and reproducible characterization. These hurdles need to be overcome through multidisciplinary collaborations across academia, pharmaceutical industry, and regulatory agencies in order to achieve the goal of eradicating cancer. This review discusses the current use of clinically approved nanomedicines, the investigation of nanomedicines in clinical trials, and the challenges that may hinder development of the nanomedicines for cancer treatment.

Porphyrin-loaded nanoparticles for cancer theranostics

Porphyrins have been used as pioneering theranostic agents not only for the photodynamic therapy, sonodynamic therapy and radiotherapy of cancer, but also for diagnostic fluorescence imaging, magnetic resonance imaging and photoacoustic imaging. A variety of porphyrins have been developed but very few of them have actually been employed in clinical trials due to their poor selectivity to tumorous tissue and high accumulation rates in the skin. In addition, most porphyrin molecules are hydrophobic and form aggregates in aqueous media. Nevertheless, the use of nanoparticles as porphyrin carriers shows great promise to overcome these shortcomings. Encapsulating or attaching porphyrins to nanoparticles makes them more suitable for tissue delivery because we can create materials with a conveniently specific tissue lifetime, specific targeting, immune tolerance, and hydrophilicity as well as other characteristics through rational design. In addition, various functional components (e.g. for targeting, imaging or therapeutic functions) can be easily introduced into a single nanoparticle platform for cancer theranostics. This review presents the current state of knowledge on porphyrin-loaded nanoparticles for the interwined imaging and therapy of cancer. The future trends and limitations of prophyrin-loaded nanoparticles are also outlined.

Development and characterization of bio-derived polyhydroxyalkanoate nanoparticles as a delivery system for hydrophobic photodynamic therapy agents

In this study, we developed and investigated nanoparticles of biologically-derived, biodegradable polyhydroxyalkanoates (PHAs) as carriers of a hydrophobic photosensitizer, 5,10,15,20-Tetrakis(4-hydroxy-phenyl)-21H, 23H-porphine (pTHPP) for photodynamic therapy (PDT). Three PHA variants; polyhydroxybutyrate, poly(hydroxybutyrate-co-hydroxyvalerate) or P(HB-HV) with 12 and 50% HV were used to formulate pTHPP-loaded PHA nanoparticles by an emulsification-diffusion method, where we compared two different poly(vinyl alcohol) (PVA) stabilizers. The nanoparticles exhibited nano-scale spherical morphology under TEM and hydrodynamic diameters ranging from 169.0 to 211.2 nm with narrow size distribution. The amount of drug loaded and the drug entrapment efficiency were also investigated. The in vitro photocytotoxicity was evaluated using human colon adenocarcinoma cell line HT-29 and revealed time and concentration dependent cell death, consistent with a gradual release pattern of pTHPP over 24 h. This study is the first demonstration using bacterially derived P(HB-HV) copolymers for nanoparticle delivery of a hydrophobic photosensitizer drug and their potential application in PDT.

Stimuli-responsive cancer therapy based on nanoparticles

Nanoparticles (NPs) have recently been well investigated for cancer therapy. Among them, those that are responsive to internal or external stimuli are promising due to their flexibility. In this feature article, we provide an overview on stimuli-sensitive cancer therapy, using pH- and reduction-sensitive NPs, as well as light- and magnetic field-responsive NPs.

In vivo studies of nanostructure-based photosensitizers for photodynamic cancer therapy

Animal models, particularly rodents, are major translational models for evaluating novel anticancer therapeutics. In this review, different types of nanostructure-based photosensitizers that have advanced into the in vivo evaluation stage for the photodynamic therapy (PDT) of cancer are described. This article focuses on the in vivo efficacies of the nanostructures as delivery agents and as energy transducers for photosensitizers in animal models. These materials are useful in overcoming solubility issues, lack of tumor specificity, and access to tumors deep in healthy tissue. At the end of this article, the opportunities made possible by these multiplexed nanostructure-based systems are summarized, as well as the considerable challenges associated with obtaining regulatory approval for such materials. The following questions are also addressed: (1) Is there a pressing demand for more nanoparticle materials? (2) What is the prognosis for regulatory approval of nanoparticles to be used in the clinic?

Nanooncology: the future of cancer diagnosis and therapy

In recent years, there has been an unprecedented expansion in the field of nanomedicine with the development of new nanoparticles for the diagnosis and treatment of cancer. Nanoparticles have unique biological properties given their small size and large surface area-to-volume ratio, which allows them to bind, absorb, and carry compounds such as small molecule drugs, DNA, RNA, proteins, and probes with high efficiency. Their tunable size, shape, and surface characteristics also enable them to have high stability, high carrier capacity, the ability to incorporate both hydrophilic and hydrophobic substances and compatibility with different administration routes, thereby making them highly attractive in many aspects of oncology. This review article will discuss how nanoparticles are able to function as carriers for chemotherapeutic drugs to increase their therapeutic index; how they can function as therapeutic agents in photodynamic, gene, and thermal therapy; and how nanoparticles can be used as molecular imaging agents to detect and monitor cancer progression.

Photodynamic nanomedicine in the treatment of solid tumors: perspectives and challenges

Photodynamic therapy (PDT) is a promising treatment strategy where activation of photosensitizer drugs with specific wavelengths of light results in energy transfer cascades that ultimately yield cytotoxic reactive oxygen species which can render apoptotic and necrotic cell death. Without light the photosensitizer drugs are minimally toxic and the photoactivating light itself is non-ionizing. Therefore, harnessing this mechanism in tumors provides a safe and novel way to selectively eradicate tumor with reduced systemic toxicity and side effects on healthy tissues. For successful PDT of solid tumors, it is necessary to ensure tumor-selective delivery of the photosensitizers, as well as, the photoactivating light and to establish dosimetric correlation of light and drug parameters to PDT-induced tumor response. To this end, the nanomedicine approach provides a promising way towards enhanced control of photosensitizer biodistribution and tumor-selective delivery. In addition, refinement of nanoparticle designs can also allow incorporation of imaging agents, light delivery components and dosimetric components. This review aims at describing the current state-of-the-art regarding nanomedicine strategies in PDT, with a comprehensive narrative of the research that has been carried out in vitro and in vivo, with a discussion of the nanoformulation design aspects and a perspective on the promise and challenges of PDT regarding successful translation into clinical application.

Photodynamic Therapy for Barrett's Esophagus and Esophageal Carcinoma

This paper reviews the use of photodynamic therapy (PDT) in patients with Barrett's esophagus and esophageal carcinoma. We describe the history of PDT, mechanics, photosensitizers for PDT in patients with esophageal disease. Finally, we discuss its utility and limitations in this setting.

In vitro and in vivo characterization of temoporfin-loaded PEGylated PLGA nanoparticles for use in photodynamic therapy

Aims: In this study we evaluated temoporfin-loaded polyethylene glycol (PEG) Poly-(D,L-lactide-co-glycolide) (PLGA) nanoparticles (NPs) as a new formulation for potential use in cancer treatment. Materials & methods: NPs were characterized for their photophysical properties, temoporfin release, cellular uptake and intracellular localization, and dark and photocytotoxicities of temoporfin by using A549, MCF10A neoT and U937 cell lines. In vivo imaging was performed on athymic nude-Foxn1 mice. Results: Temoporfin was highly aggregated within the NPs and the release of temoporfin monomers was faster from PEGylated PLGA NPs than from non-PEGylated ones. PEGylation significantly reduced the cellular uptake of NPs by the differentiated promonocytic U937 cells, revealing the stealth properties of the delivery system. Dark cytotoxicity of temoporfin delivered by NPs was less than that of free temoporfin in standard solution (Foscan®, Biolitec AG [Jena, Germany]), whereas phototoxicity was not reduced. Temoporfin delivered to mice by PEGylated PLGA NPs exhibits therapeutically favorable tissue distribution. Conclusion: These encouraging results show promise in using PEGylated PLGA NPs for improving the delivery of photosensitizers for photodynamic therapy.

Original submitted 30 March 2011; Revised submitted 9 July 2011

Design of photosensitizer/cyclodextrin nanoassemblies: spectroscopy, intracellular delivery and photodamage

The engineering of multifunctional nanoparticles carrying photosensitizer drugs (PS) and exposing binding groups for cellular receptors is of increasing interest in therapeutics and diagnostics applications. Natural and modified cyclodextrins (CDs) offer useful scaffolds to bind PS guests by supramolecular interactions. In particular, amphiphilic β-CDs, which form nanoaggregates of diverse shape and size according to the polarity of substituent groups on the rims, include in their different compartments as CD cavity, hydrophilic and hydrophobic portion, PS with different physicochemical properties. PS embedded in cationic amphiphilic CD nanoassemblies are effective in inducing photodynamic damage in cancer cells. For a carrier/PS system to be used in photodynamic therapy (PDT) or photodynamic diagnosis (PDD), the appropriate combination of the delivery characteristics with the preservation of the photodynamic activity of the PS is strictly required. Homogeneous multilayer films based on cationic amphiphilic β-CD entrapping anionic porphyrins can be constructed to exploit interfacial electrostatic interactions between the two components. The capability of CDs to generate restricted microenvironments for PS which can facilitate photoinduced energy transfer with suitable donor molecules was investigated for potential application in fluorescence diagnosis. Besides, recent findings suggest that PDT could represent a useful tool for properly addressing an alternative approach for killing pathogens and combating infections at a clinical level. Finally, modified CDs can bind gold nanoparticles, yielding hybrid organic/inorganic nanoparticles which were studied in water solution and after casting on solid substrates. These binary assemblies could further encapsulate PS or other conventional drugs, opening new intriguing routes on multimodal therapy.

Nanostructured delivery system for zinc phthalocyanine: preparation, characterization, and phototoxicity study against human lung adenocarcinoma A549 cells

In this study, zinc phthalocyanine (ZnPc) was loaded onto poly-ɛ-caprolactone (PCL) nanoparticles (NPs) using a solvent emulsification–evaporation method. The process yield and encapsulation efficiency were 74.2% ± 1.2% and 67.1% ± 0.9%, respectively. The NPs had a mean diameter of 187.4 ± 2.1 nm, narrow distribution size with a polydispersity index of 0.096 ± 0.004, zeta potential of −4.85 ± 0.21 mV, and spherical shape. ZnPc has sustained release, following Higuchi’s kinetics. The photobiological activity of the ZnPc-loaded NPs was evaluated on human lung adenocarcinoma A549 cells. Cells were incubated with free ZnPc or ZnPc-loaded NPs for 4 h and then washed with phosphate-buffered saline. Culture medium was added to the wells containing the cells. Finally, the cells were exposed to red light (660 nm) with a light dose of 100 J/cm². The cellular viability was determined after 24 h of incubation. ZnPc-loaded NPs and free photosensitizer eliminated about 95.9% ± 1.8% and 28.7% ± 2.2% of A549 cells, respectively. The phototoxicity was time dependent up to 4 h and concentration dependent at 0–5 μg ZnPc. The cells viability decreased with the increase of the light dose in the range of 10–100 J/cm². Intense lysis was observed in the cells incubated with the ZnPcloaded NPs and irradiated with red light. ZnPc-loaded PCL NPs are the release systems that promise photodynamic therapy use.

Polymeric nanoparticles for photodynamic therapy

Photodynamic therapy is a relatively new clinical therapeutic modality that is based on three key components: photosensitizer, light, and molecular oxygen. Nanoparticles, especially targeted ones, have recently emerged as an efficient carrier of drugs or contrast agents, or multiple kinds of them, with many advantages over molecular drugs or contrast agents, especially for cancer detection and treatment. This paper describes the current status of PDT, including basic mechanisms, applications, and challenging issues in the optimization and adoption of PDT; as well as recent developments of nanoparticle-based PDT agents, their advantages, designs and examples of in vitro and in vivo applications, and demonstrations of their capability of enhancing PDT efficacy over existing molecular drug-based PDT.

Enhanced cellular uptake of chlorine e6 mediated by stearic acid-grafted chitosan oligosaccharide micelles

Chlorines are attractive compounds for photodynamic therapy because of their high absorption in the red wavelength region. The stearic acid-grafted chitosan oligosaccharide (CSO-SA) micelles have been presented as potential candidates for intracellular drug delivery carrier because of their special structure. In this study, CSO-SA micelles were prepared to encapsulate chlorine e6 (Ce6). The physicochemical properties of synthesized CSO-SA micelles were characterized. The critical micelle concentration (CMC) of CSO-SA with 4.96% amino substituted degree (SD %) was about 36.27 +/- 1.51 microg/mL. The Ce6-loaded CSO-SA micelles were then prepared by a dialysis method, and the properties and drug release profiles of Ce6- loaded CSO-SA micelles (CSO-SA/Ce6) were investigated. The loading of Ce6 in the CSO-SA micelles could reach higher drug encapsulation efficiency (%), which was approximately 100%. The size of CSO-SA/Ce6 decreased after the loading of Ce6. The zeta potential of CSO-SA/Ce6 and the drug release rate decreased with the loading content of drug. After the Ce6 molecules were encapsulated into the micelles of CSO-SA, the cellular uptake percentage of Ce6 was much more than that of the free drug. And the cellular uptake percentage of CSO-SA/Ce6 micelles was increased with the incubation time in a short period.

The cellular uptake of meta-tetra(hydroxyphenyl)chlorin entrapped in organically modified silica nanoparticles is mediated by serum proteins

Nanosized objects made of various materials are gaining increasing attention as promising vehicles for the delivery of therapeutic and diagnostic agents for cancer. Photodynamic therapy (PDT) appears to offer a very attractive opportunity to implement drug delivery systems since no release of the sensitizer is needed to obtain the therapeutic effect and the design of the nanovehicle should be much easier. The aim of our study was to investigate the use of organic-modified silica nanoparticles (NPs) for the delivery of the second-generation photosensitizer meta-tetra(hydroxyphenyl)chlorin (mTHPC) to cancer cells in vitro. mTHPC was entrapped in NPs (approximately 33 nm diameter) in a monomeric form which produced singlet oxygen with a high efficiency. In aqueous media with high salt concentrations, the NPs underwent aggregation and precipitation but their stability could be preserved in the presence of foetal bovine serum. The cellular uptake, localization and phototoxic activity of mTHPC was determined comparatively in human oesophageal cancer cells after its delivery by the NPs and the standard solvent ethanol/poly(ethylene glycol) 400/water (20:30:50, by vol). The NP formulation reduced the cellular uptake of mTHPC by about 50% in comparison to standard solvent while it did not affect the concentration-dependent photokilling activity of mTHPC and its intracellular localization. Fluorescence resonance energy transfer measurements, using NPs with mTHPC physically entrapped and a cyanine covalently linked, and ultracentrifugation experiments indicated that mTHPC is transferred from NPs to serum proteins when present in the medium. However, the coating of the NP surface with poly(ethylene glycol) largely prevented the transfer to proteins. In conclusion, mTHPC is rapidly transferred from the uncoated nanoparticles to the serum proteins and then internalized by the cells as a protein complex, irrespective of its modality of delivery.

Toxicity of therapeutic nanoparticles

A total of six nanotherapeutic formulations are already approved for medical use and more are in the approval pipeline currently. Despite the massive research effort in nanotherapeutic materials, there is relatively little information about the toxicity of these materials or the tools needed to assess this toxicity. Recently, the scientific community has begun to respond to the paucity of information by investing in the field of nanoparticle toxicology. This review is intended to provide an overview of the techniques needed to assess toxicity of these therapeutic nanoparticles and to summarize the current state of the field. We begin with background on the toxicological assessment techniques used currently as well as considerations in nanoparticle dosing. The toxicological research overview is divided into the most common applications of therapeutic nanoparticles: drug delivery, photodynamic therapy and bioimaging. We end with a perspective section discussing the current technological gaps and promising research aimed at addressing those gaps.