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

Recent advances in the development of poly(ester amide)s-based carriers for drug delivery

Biodegradable and biocompatible biomaterials have several important applications in drug delivery. The biomaterial family known as poly(ester amide)s (PEAs) has garnered considerable interest because it exhibits the benefits of both polyester and polyamide, as well as production from readily available raw ingredients and sophisticated synthesis techniques. Specifically, α-amino acid-based PEAs (AA-PEAs) are promising carriers because of their structural flexibility, biocompatibility, and biodegradability. Herein, we summarize the latest applications of PEAs in drug delivery systems, including antitumor, gene therapy, and protein drugs, and discuss the prospects of drug delivery based on PEAs, which provides a reference for designing safe and efficient drug delivery carriers.

Enhancing antitumor efficacy of NIR-I region zinc phthalocyanine@upconversion nanoparticle through lysosomal escape and mitochondria targeting

Accurately visualizing the intracellular trafficking of upconversion nanoparticles (UCNPs) loaded with phthalocyanines and achieving precise photodynamic therapy (PDT) using near-infrared (NIR) laser irradiation still present challenges. In this study, a novel NIR laser-triggered upconversion luminescence (UCL) imaging-guided nanoparticle called FA@TPA-NH-ZnPc@UCNPs (FTU) was developed for PDT. FTU consisted of UCNPs, folic acid (FA), and triphenylamino-phenylaniline zinc phthalocyanine (TPA-NH-ZnPc). Notably, TPA-NH-ZnPc showcases aggregation-induced emission (AIE) characteristic and NIR absorption properties at 741 nm, synthesized initially via molybdenum-catalyzed condensation reaction. The UCL emitted by FTU enable real-time visualization of their subcellular localization and intracellular trafficking within ovarian cancer HO-8910 cells. Fluorescence images revealed that FTU managed to escape from lysosomes due to the "proton sponge" effect of TPA-NH-ZnPc. The FA ligands on the surface of FTU further directed their transport and accumulation within mitochondria. When excited by a 980 nm laser, FTU exhibited UCL and activated TPA-NH-ZnPc, consequently generating cytotoxic singlet oxygen (1O2), disrupted mitochondrial function and induced apoptosis in cancer cells, which demonstrated great potential for tumor ablation.

Fluorinated Organic Polymers for Cancer Drug Delivery

In the realm of cancer therapy, the spotlight is on nanoscale pharmaceutical delivery systems, especially polymer-based nanoparticles, for their enhanced drug dissolution, extended presence in the bloodstream, and precision targeting achieved via surface engineering. Leveraging the amplified permeation and retention phenomenon, these systems concentrate therapeutic agents within tumor tissues. Nonetheless, the hurdles of systemic toxicity, biological barriers, and compatibility with living systems persist. Fluorinated polymers, distinguished by their chemical idiosyncrasies, are poised for extensive biomedical applications, notably in stabilizing drug metabolism, augmenting lipophilicity, and optimizing bioavailability. Material science heralds the advent of fluorinated polymers that, by integrating fluorine atoms, unveil a suite of drug delivery merits: the hydrophobic traits of fluorinated alkyl chains ward off lipid or protein disruption, the carbon-fluorine bond's stability extends the drug's lifecycle in the system, and a lower alkalinity coupled with a diminished ionic charge bolsters the drug's ability to traverse cellular membranes. This comprehensive review delves into the utilization of fluorinated polymers for oncological pharmacotherapy, elucidating their molecular architecture, synthetic pathways, and functional attributes, alongside an exploration of their empirical strengths and the quandaries they encounter in both experimental and clinical settings.

A Journey of Challenges and Victories: A Bibliometric Worldview of Nanomedicine since the 21st Century

Nanotechnology profoundly affects the advancement of medicine. Limitations in diagnosing and treating cancer and chronic diseases promote the growth of nanomedicine. However, there are very few analytical and descriptive studies regarding the trajectory of nanomedicine, key research powers, present research landscape, focal investigative points, and future outlooks. Herein, articles and reviews published in the Science Citation Index Expanded of Web of Science Core Collection from first January 2000 to 18th July 2023 are analyzed. Herein, a bibliometric visualization of publication trends, countries/regions, institutions, journals, research categories, themes, references, and keywords is produced and elaborated. Nanomedicine-related academic output is increasing since the COVID-19 pandemic, solidifying the uneven global distribution of research performance. While China leads in terms of publication quantity and has numerous highly productive institutions, the USA has advantages in academic impact, commercialization, and industrial value. Nanomedicine integrates with other disciplines, establishing interdisciplinary platforms, in which drug delivery and nanoparticles remain focal points. Current research focuses on integrating nanomedicine and cell ferroptosis induction in cancer immunotherapy. The keyword "burst testing" identifies promising research directions, including immunogenic cell death, chemodynamic therapy, tumor microenvironment, immunotherapy, and extracellular vesicles. The prospects, major challenges, and barriers to addressing these directions are discussed.

Porphyrin-based covalent organic frameworks as doxorubicin delivery system for chemo-photodynamic synergistic therapy of tumors

Photodynamic therapy (PDT) is a non-invasive treatment method that has garnered significant attention in recent years. Nanoparticle-based drug delivery systems can achieve targeted drug release, thereby significantly reducing side effects and enhancing therapeutic efficacy. In this study, a covalent organic framework (COF) with an approximately spherical structure connected by azo bonds was synthesized. The synthesized COF was utilized as a hypoxia-responsive carrier for doxorubicin (DOX) drug delivery and was modified with hyaluronic acid (HA). DOX@COF@HA exhibited a reactive release under hypoxic conditions. Under normal oxygen conditions, the release of DOX was 16.9 %, increasing to 60.2 % with the addition of sodium hydrosulfite. In vitro experiments revealed that the group combining photodynamic therapy with chemotherapy exhibited the lowest survival rates for 4T1 and MHCC97-L cells. In vivo experiments further validated the effectiveness of combination therapy, resulting in a tumor volume of only 33 mm3 after treatment, with no significant change in mouse weight during the treatment period. DOX@COF@HA nanoplatforms exhibit substantial potential in tumor treatment.

Combining Multiple Photosensitizer Modules into One Supramolecular System for Synergetic Enhanced Photodynamic Therapy

Photodynamic therapy (PDT), as an emerging cancer treatment, requires the development of highly desirable photosensitizers (PSs) with integrated functional groups to achieve enhanced therapeutic efficacy. Coordination-driven self-assembly (CDSA) would provide an alternative approach for combining multiple PSs synergistically. Here, we demonstrate a simple yet powerful strategy of combining conventional chromophores (tetraphenylethylene, porphyrin, or Zn-porphyrin) with pyridinium salt PSs together through condensation reactions, followed by CDSA to construct a series of novel metallo-supramolecular PSs (S1-S3). The generation of reactive oxygen species (ROS) is dramatically enhanced by the direct combination of two different PSs, and further reinforced in the subsequent ensembles. Among all the ensembles, S2 with two porphyrin cores shows the highest ROS generation efficiency, specific interactions with lysosome, and strong emission for probing cells. Moreover, the cellular and living experiments confirm that S2 has excellent PDT efficacy, biocompatibility, and biosafety. As such, this study will enable the development of more efficient PSs with potential clinical applications.

Biological Interaction and Imaging of Ultrasmall Gold Nanoparticles

The ultrasmall gold nanoparticles (AuNPs), serving as a bridge between small molecules and traditional inorganic nanoparticles, create significant opportunities to address many challenges in the health field. This review discusses the recent advances in the biological interactions and imaging of ultrasmall AuNPs. The challenges and the future development directions of the ultrasmall AuNPs are presented.

Unleashing the power of porphyrin photosensitizers: Illuminating breakthroughs in photodynamic therapy

This comprehensive review provides the current trends and recent developments of porphyrin-based photosensitizers. We discuss their evolution from first-generation to third-generation compounds, including cutting-edge nanoparticle-integrated derivatives, and explores their pivotal role in advancing photodynamic therapy (PDT) for enhanced cancer treatment. Integrating porphyrins with nanoparticles represents a promising avenue, offering improved selectivity, reduced toxicity, and heightened biocompatibility. By elucidating recent breakthroughs, innovative methodologies, and emerging applications, this review provides a panoramic snapshot of the dynamic field, addressing challenges and charting prospects. With a focus on harnessing reactive oxygen species (ROS) through light activation, PDT serves as a minimally invasive therapeutic approach. This article offers a valuable resource for researchers, clinicians, and PDT enthusiasts, highlighting the potential of porphyrin photosensitizers to improve the future of cancer therapy.

Advancement in Biopolymer Assisted Cancer Theranostics

Applications of nanotechnology have increased the importance of research and nanocarriers, which have revolutionized the method of drug delivery to treat several diseases, including cancer, in the past few years. Cancer, one of the world's fatal diseases, has drawn scientists' attention for its multidrug resistance to various chemotherapeutic drugs. To minimize the side effects of chemotherapeutic agents on healthy cells and to develop technological advancement in drug delivery systems, scientists have developed an alternative approach to delivering chemotherapeutic drugs at the targeted site by integrating it inside the nanocarriers like synthetic polymers, nanotubes, micelles, dendrimers, magnetic nanoparticles, quantum dots (QDs), lipid nanoparticles, nano-biopolymeric substances, etc., which has shown promising results in both preclinical and clinical trials of cancer management. Besides that, nanocarriers, especially biopolymeric nanoparticles, have received much attention from researchers due to their cost-effectiveness, biodegradability, treatment efficacy, and ability to target drug delivery by crossing the blood-brain barrier. This review emphasizes the fabrication processes, the therapeutic and theragnostic applications, and the importance of different biopolymeric nanocarriers in targeting cancer both in vitro and in vivo, which conclude with the challenges and opportunities of future exploration using biopolymeric nanocarriers in onco-therapy with improved availability and reduced toxicity.

Targeted therapy of breast tumor by PLGA-based nanostructures: The versatile function in doxorubicin delivery

Breast carcinoma is a molecularly diverse illness, and it is among the most prominent and often reported malignancies in female across the globe. Surgical intervention, chemotherapy, immunotherapy, gene therapy, and endocrine treatment are among the currently viable treatment options for the carcinoma of breast. Chemotherapy is among the most prevalent cancer management strategy. Doxorubicin (DOX) widely employed as a cytostatic medication for the treatment of a variety of malignancies. Despite its widespread acceptance and excellent efficacy against an extensive line up of neoplasia, it has a variety of shortcomings that limit its therapeutic potential in the previously mentioned indications. Employment of nanoparticulate systems has come up as a unique chemo medication delivery strategy and are being considerably explored for the amelioration of breast carcinoma. Polylactic-co-glycolic acid (PLGA)-based nano systems are being utilized in a number of areas within the medical research and medication delivery constitutes one of the primary functions for PLGA given their inherent physiochemical attributes, including their aqueous solubility, biocompatibility, biodegradability, versatility in formulation, and limited toxicity. Herein along with the different application of PLGA-based nano formulations in cancer therapy, the present review intends to describe the various research investigations that have been conducted to enumerate the effectiveness of DOX-encapsulated PLGA nanoparticles (DOX-PLGA NPs) as a feasible treatment option for breast cancer.

Recent Advances in Doxorubicin Formulation to Enhance Pharmacokinetics and Tumor Targeting

Doxorubicin (DOX), a widely used drug in cancer chemotherapy, induces cell death via multiple intracellular interactions, generating reactive oxygen species and DNA-adducted configurations that induce apoptosis, topoisomerase II inhibition, and histone eviction. Despite its wide therapeutic efficacy in solid tumors, DOX often induces drug resistance and cardiotoxicity. It shows limited intestinal absorption because of low paracellular permeability and P-glycoprotein (P-gp)-mediated efflux. We reviewed various parenteral DOX formulations, such as liposomes, polymeric micelles, polymeric nanoparticles, and polymer-drug conjugates, under clinical use or trials to increase its therapeutic efficacy. To improve the bioavailability of DOX in intravenous and oral cancer treatment, studies have proposed a pH- or redox-sensitive and receptor-targeted system for overcoming DOX resistance and increasing therapeutic efficacy without causing DOX-induced toxicity. Multifunctional formulations of DOX with mucoadhesiveness and increased intestinal permeability through tight-junction modulation and P-gp inhibition have also been used as orally bioavailable DOX in the preclinical stage. The increasing trends of developing oral formulations from intravenous formulations, the application of mucoadhesive technology, permeation-enhancing technology, and pharmacokinetic modulation with functional excipients might facilitate the further development of oral DOX.

An X-ray activatable gold nanorod encapsulated liposome delivery system for mitochondria-targeted photodynamic therapy (PDT)

In this work, we developed a mitochondria-targeted nanomaterial for neoadjuvant X-ray-triggered photodynamic therapy of rectal cancer. Herein, we designed a biodegradable liposome incorporating a photosensitizer, verteporfin, to generate X-ray-induced reactive oxygen species, gold nanorods as radiation enhancers, and triphenylphosphonium as the mitochondrial targeting moiety. The average size of the nanocarrier was about 150 nm. Due to the synergetic effect between X-ray and a combination of verteporfin and gold nanorods, as well as precise site-targeted TPP-modified liposomal nanocarriers, our nanoconjugates generated sufficient cytotoxic singlet oxygen within the mitochondria under X-ray irradiation, triggering the loss of membrane potential and mitochondria-related apoptosis of cancer cells.

Cancer cell membrane camouflaging mesoporous nanoplatform interfering with cellular redox homeostasis to amplify photodynamic therapy on oral carcinoma

The efficacy of photodynamic therapy (PDT) is still limited by the inefficient utilisation of generated ROS in tumours due to cellular redox homeostasis. To improve the therapeutic efficacy for oral carcinoma, biomimetic cell membrane-coated mesoporous nanoplatform was tailored to interfere with cellular redox homeostasis for amplified PDT. In this study, CAL-27 cancer cell membrane (CM) was encapsulated onto the mesoporous silica NPs (MSN), which were preloaded with Chlorin e6 (Ce6) and Curcumin (Cur). The biomimetic nanoparticles displayed a size of around 120 nm, which had excellent cytotoxicity under a laser and increased uptake ability to tumour cell. After internalised by cancer cells, the released Cur could effectively disturb ROS-defence system by suppressing TrxR activity, and decreasing TrxR-2 expression (p < 0.05), leading to enhanced cancer cell killing ability of PDT. The biomimetic system was found to selectively accumulate in the tumour due to its homologous targeting capability and inhibit tumour growth significantly. In a word, the biomimetic nanoplatform apparently enhanced the therapeutic effect of PDT on tumours by Cur disturbing the ROS-defence system, which exhibited a new way to enhance PDT.

Recent Biomedical Applications of Coupling Nanocomposite Polymeric Materials Reinforced with Variable Carbon Nanofillers

The hybridization between polymers and carbon materials is one of the most recent and crucial study areas which abstracted more concern from scientists in the past few years. Polymers could be classified into two classes according to the source materials synthetic and natural. Synthetic polymeric materials have been applied over a floppy zone of industrial fields including the field of biomedicine. Carbon nanomaterials including (fullerene, carbon nanotubes, and graphene) classified as one of the most significant sources of hybrid materials. Nanocarbons are improving significantly mechanical properties of polymers in nanocomposites in addition to physical and chemical properties of the new materials. In all varieties of proposed bio-nanocomposites, a considerable improvement in the microbiological performance of the materials has been explored. Various polymeric materials and carbon-course nanofillers were present, along with antibacterial, antifungal, and anticancer products. This review spots the light on the types of synthetic polymers-based carbon materials and presented state-of-art examples on their application in the area of biomedicine.

Photochemical Internalization Using Natural Anticancer Drugs, Antimetabolites, and Nanoformulations: A Systematic Study against Breast and Pancreatic Cancer Cell Lines

Photochemical internalization (PCI) is a novel, minimally invasive drug delivery technology that facilitates the delivery of therapeutic molecules into the cytosol of cells. In this work, PCI was utilized in an effort to enhance the therapeutic index of the existing anticancer drugs as well as novel nanοformulations against breast and pancreatic cancer cells. Frontline anticancer drugs were tested with bleomycin as a benchmark PCI control; namely, three vinca alkaloids (vincristine, vinorelbine, and vinblastine), two taxanes (docetaxel and paclitaxel), two antimetabolites (gemcitabine and capecitabine), a combination of taxanes with antimetabolites, and two nano-sized formulations (squalene- and polymer-bound gemcitabine derivatives) were tested in a 3D PCI in vitro model. Strikingly, we discovered that several drug molecules exhibited remarkably augmented therapeutic activity by several orders of magnitude compared to their respective controls (without PCI technology or directly compared with bleomycin controls). Nearly all drug molecules showed enhanced therapeutic efficiency, but more interestingly, we traced several drug molecules that showed multi-fold enhancement (ranging from 5000- up to 170,000-fold enhancement) in their IC₇₀ indices. Interestingly, PCI delivery of the vinca alkaloids (especially PCI-vincristine), and some of the nanoformulations tested, was seen to perform impressively across all of the treatment outcomes of potency, efficacy, and synergy─as determined by means of a cell viability assay. The study constitutes a systematic guide for the development of future PCI-based therapeutic modalities for precision oncology.

Cu(ii)-BODIPY photosensitizer for CAIX overexpressed cancer stem cell therapy

Chemoresistance originating from cancer stem cells (CSCs) is a major cause of cancer treatment failure and highlights the need to develop CSC-targeting therapies. Although enormous progress in both photodynamic therapy (PDT) and chemodynamic therapy (CDT) has been made in recent decades, the efficacy of these modalities against CSC remains limited. Here, we report a new generation photosensitizer, CA9-BPS-Cu(ii), a system that combines three subunits within a single molecule, namely a copper catalyst for CDT, a boron dipyrromethene photosensitizer for PDT, and acetazolamide for CSC targeting via carbonic anhydrase-9 (CA9) binding. A therapeutic effect in MDA-MB-231 cells was observed that is ascribed to elevated oxidative stress mediated by a combined CDT/PDT effect, as well as through copper-catalysed glutathione oxidation. The CSC targeting ability of CA9-BPS-Cu(ii) was evident from the enhanced affinity of CA9-BPS-Cu(ii) towards CD133-positive MDA-MB-231 cells where CA9 is overexpressed vs. CD133-negative cells. Moreover, the efficacy of CA9-BPS-Cu(ii) was successfully demonstrated in a xenograft mouse tumour model.

A Review on Recent Advances in Mannose-Functionalized Targeted Nanocarrier Delivery Systems in Cancer and Infective Therapeutics

Unmodified nanocarriers used in the chemotherapy of cancers and various infectious diseases exhibit prolonged blood circulation time, prevent enzymatic degradation and increase chemical stability of encapsulated therapeutics. However, off-target effect and lack of specificity associated with unmodified nanoparticles (NPs) limit their applications in the health care system. Mannose (Man) receptors with significant overexpression on antigen-presenting cells and macrophages are among the most admired targets for cancer and anti-infective therapeutics. Therefore, development of Man functionalized nanocarriers targeting Man receptors, for target specific drug delivery in the chemotherapy have been extensively studied. Present review expounds diverse Man-conjugated NPs with their potential for targeted drug delivery, improved biodistribution profiles and localization. Additionally, the review gives detailed account of the interactions of mannosylated NPs with various biological systems and their characterization not discussed in earlier published reports is discussed.

Nanotheranostics-based Management of Head and Neck Cancer

Head and neck cancer is affecting a large sort of population. Many treatments are available on a regular base, but they have their limitations. Diagnosis in the early stage is essential to cope with the disease which is a limitation in the majority of present diagnostic tools. Many of them are invasive methods that lead to patient discomfort. Interventional nanothernostics is an emerging field in the management of Head and Neck cancer. It facilitates both diagnostic and therapeutic approaches. It also helps with the overall management of the disease. This method allows the early and accurate detection of the disease which improvises the chances of recovery. Additionally, it makes sure that the medicine is delivered specifically to increase clinical outcomes and reduce side effects. The use of radiation in addition to the medicine supplied can produce a synergistic effect. It contains several nanoparticles, including silicon and gold nanoparticles. This review paper focuses on the shortcomings of existing therapeutic techniques and how nanotheranostics fills the void.

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.

Biofunctional Layered Double Hydroxide Nanohybrids for Cancer Therapy

Layered double hydroxides (LDHs) with two-dimensional nanostructure are inorganic materials that have attractive advantages such as biocompatibility, facile preparation, and high drug loading capacity for therapeutic bioapplications. Since the intercalation chemistry of DNA molecules into the LDH materials were reported, various LDH nanohybrids have been developed for biomedical drug delivery system. For these reasons, LDHs hybridized with numerous therapeutic agents have a significant role in cancer imaging and therapy with targeting functions. In this review, we summarized the recent advances in the preparation of LDH nanohybrids for cancer therapeutic strategies including gene therapy, chemotherapy, immunotherapy, and combination therapy.

The Potential of Antibody Technology and Silver Nanoparticles for Enhancing Photodynamic Therapy for Melanoma

Melanoma is highly aggressive and is known to be efficient at resisting drug-induced apoptotic signals. Resection is currently the gold standard for melanoma management, but it only offers local control of the early stage of the disease. Metastatic melanoma is prone to recurrence, and has a poor prognosis and treatment response. Thus, the need for advanced theranostic alternatives is evident. Photodynamic therapy has been increasingly studied for melanoma treatment; however, it relies on passive drug accumulation, leading to off-target effects. Nanoparticles enhance drug biodistribution, uptake and intra-tumoural concentration and can be functionalised with monoclonal antibodies that offer selective biorecognition. Antibody–drug conjugates reduce passive drug accumulation and off-target effects. Nonetheless, one limitation of monoclonal antibodies and antibody–drug conjugates is their lack of versatility, given cancer’s heterogeneity. Monoclonal antibodies suffer several additional limitations that make recombinant antibody fragments more desirable. SNAP-tag is a modified version of the human DNA-repair enzyme, O6-alkylguanine-DNA alkyltransferase. It reacts in an autocatalytic and covalent manner with benzylguanine-modified substrates, providing a simple protein labelling system. SNAP-tag can be genetically fused with antibody fragments, creating fusion proteins that can be easily labelled with benzylguanine-modified payloads for site-directed delivery. This review aims to highlight the benefits and limitations of the abovementioned approaches and to outline how their combination could enhance photodynamic therapy for melanoma.

Covalent Organic Framework Nanocarriers of Singlet Oxygen for Oxygen-Independent Concurrent Photothermal/Photodynamic Therapy to Ablate Hypoxic Tumors

Photodynamic therapy (PDT) of cancers is seriously restricted by tumor hypoxia. In addition to the intrinsic hypoxic microenvironment, continuous photoirradiation further aggravates intratumoral hypoxia, thereby reducing the PDT effect significantly. Oxygen-independent PDT is recognized as an efficient approach to overcome this issue. Herein, singlet oxygen (¹ O₂ )-stored covalent organic framework (COF) nanoparticles loading the near-infrared (NIR) dye cypate, which realize oxygen-independent ¹ O₂ production for concurrent photothermal therapy (PTT) and PDT under NIR irradiation, are presented. The cypate-loading COF nanoparticles are prepared by using the photosensitizers and ¹ O₂ -stored molecules via formation of Schiff base bonds, followed by coverage of poly(vinyl pyrrolidone). The COF nanoparticles significantly improve the photostability and photothermal conversion efficiency of cypate by protecting them from photodegradation under NIR irradiation. Upon 660 nm laser irradiation, ¹ O₂ is produced by the photosensitizer motifs and is successfully stored by the ¹ O₂ -stored moieties. After intravenous injection and tumor accumulation, the COF nanoparticles can generate heat quickly upon 808 nm irradiation which induces the efficient release of the stored ¹ O₂ to ablate tumors via O₂ -independent concurrent PTT/PDT. Accordingly, the COF nanocarriers of ¹ O₂ provide a paradigm to develop O₂ -independent concurrent PTT/PDT for precise cancer treatment upon NIR irradiation.

BODIPY-Based Nanomaterials—Sensing and Biomedical Applications

Cancerous diseases are rightfully considered among the most lethal, which have a consistently negative effect when considering official statistics in regular health reports around the globe. Nowadays, metallic nanoparticles can be potentially applied in medicine as active pharmaceuticals, adjustable carriers, or distinctive enhancers of physicochemical properties if combined with other drugs. Boron dipyrromethene (BODIPY) molecules have been considered for future applications in theranostics in the oncology field, thus expanding the potential of conceivable applicability. Hence, taking into account positive practical features of both metal-based nanostructures and BODIPY derivatives, the present study aims to gather recent results connected to BODIPY-conjugated metallic nanoparticles. This is with respect to their expediency in the diagnosis and treatment of tumor ailments as well as in sensing of heavy metals. To fulfill the designated objectives, multiple research documents were analyzed concerning the latest discoveries within the scope of BODIPY-based nanomaterials with particular emphasis on their utilization for diagnostical sensing as well as cancer diagnostics and therapy. In addition, collected examples of mentioned conjugates were presented in order to draw the attention of the scientific community to their practical applications, elucidate the topic in a consistent manner, and inspire fellow researchers for new findings.

Glutathione-depleting polymer delivering chlorin e6 for enhancing photodynamic therapy

The therapeutic effect of photodynamic therapy (PDT) is highly dependent on the intracellular production of reactive oxygen species (ROS). However, the ROS generated by photosensitizers can be consumed by the highly concentrated glutathione (GSH) in tumor cells, severely impairing the therapeutic effect of PDT. Herein, we synthesized a GSH-scavenging copolymer to deliver photosensitizer chlorin e6 (Ce6). The pyridyl disulfide groups, which have faster reactivity with the thiol groups of GSH than other disulfide groups, were grafted onto a hydrophobic block to encapsulate the Ce6. Under NIR irradiation, the Ce6 generated ROS to kill tumor cells, and the pyridyl disulfide groups depleted the GSH to prevent ROS consumption, which synergistically enhanced the therapeutic effect of PDT. In vitro and in vivo experiments confirmed the combinatory antitumor effect of Ce6-induced ROS generation and the pyridyl disulfide group-induced GSH depletion. Therefore, the pyridyl disulfide group-grafted amphiphilic copolymer provides a more efficient strategy for enhancing PDT and has promising potential for clinical application.

Layered double hydroxide-based nanomaterials for biomedical applications

Against the backdrop of increased public health awareness, inorganic nanomaterials have been widely explored as promising nanoagents for various kinds of biomedical applications. Layered double hydroxides (LDHs), with versatile physicochemical advantages including excellent biocompatibility, pH-sensitive biodegradability, highly tunable chemical composition and structure, and ease of composite formation with other materials, have shown great promise in biomedical applications. In this review, we comprehensively summarize the recent advances in LDH-based nanomaterials for biomedical applications. Firstly, the material categories and advantages of LDH-based nanomaterials are discussed. The preparation and surface modification of LDH-based nanomaterials, including pristine LDHs, LDH-based nanocomposites and LDH-derived nanomaterials, are then described. Thereafter, we systematically describe the great potential of LDHs in biomedical applications including drug/gene delivery, bioimaging diagnosis, cancer therapy, biosensing, tissue engineering, and anti-bacteria. Finally, on the basis of the current state of the art, we conclude with insights on the remaining challenges and future prospects in this rapidly emerging field.

Gold Nanoparticle Embedded Stimuli-Responsive Functional Glycopolymer: A Potential Material for Synergistic Chemo-Photodynamic Therapy of Cancer Cells

Photodynamic therapy has emerged as a non-invasive treatment modality for several types of cancers. However, conventional hydrophobic photosensitizers (PS) suffer from low water solubility and poor tumor-targeting ability. Therefore, PS modified with glycopolymers can offer adequate water solubility, biocompatibility and tumor-targeting ability due to the presence of multiple sugar units. In this study, a well-defined block copolymer (BCP) poly(3-O-methacryloyl-D-glucopyranose)-b-poly(2-(4-formylbenzoyloxy)ethylmethacrylate) (PMAG-b-PFBEMA) containing pendant glucose and aldehyde units was synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization method. A water-soluble PS (toluidine blue O; TBO) and a potent anti-cancer drug, Doxorubicin (Dox) were introduced to the polymer backbone via acid-labile Schiff-base reaction (PMAG-b-PFBEMA_TBO_Dox). The PMAG-b-PFBEMA_TBO_Dox was then anchored on the surface of AuNP via electrostatic interaction. This hybrid system exhibited excellent reactive oxygen species (ROS) generating ability under exposure of 630 nm LED along with triggered release of Dox under the acidic pH of tumor cells. The in vitro cytotoxicity study on human breast cancer cell line, MDA MB 231, for this hybrid system showed promising results due to the synergistic effect of ROS and Dox released. Thus, this glycopolymer-based dual (chemo-photodynamic) therapy model can work as potential material for future therapeutics. This article is protected by copyright. All rights reserved.

Microneedles loaded with glutathione-scavenging composites for nitric oxide enhanced photodynamic therapy of melanoma

Photodynamic therapy (PDT) represents an attractive promising route for melanoma treatment. However, its therapeutic efficacy is compromised by inefficient drug delivery and high glutathione (GSH) levels in cancer cells. To overcome these challenges, microneedles (MNs) system loaded with GSH-scavenging nanocomposites was presented for nitric oxide (NO) enhanced PDT. The nanocomposites consisted of S-nitroso-N-acrylate penicillamine (SNAP; a NO donor) grafted fourth-generation polyamide amine dendrimer (G₄) and chlorin e6 (Ce6). Upon local insertion of polyvinylpyrrolidone MNs, G₄-SNAP/Ce6 composites were fast delivered and significantly amplified the therapeutic effects during PDT, via GSH depletion and reactive nitrogen species generation. Even with a single administration and low power light exposure, MNs with G₄-SNAP/Ce6 effectively halt the tumor progression. The system demonstrated better cancer ablation efficacy than Ce6 alone toward melanoma. The strategy may inspire new ideas for future PDT-related therapy for skin tumors.

Heterojunction engineered bioactive chlorella for cascade promoted cancer therapy

The hypoxic tumor microenvironment is one of most major hurdles restraining the anti-tumor efficiency of photodynamic therapy (PDT). Herein, active photosynthetic Chlorophyceae (Chlorella, Chl) functionalized with black phosphorus nanosheets (BPNSs) through polyaspartic acid (PASP) and Fe³⁺ mediating "Lego building method" are utilized for photocatalyzed oxygen-evolving to realize photosynthesis enhanced synergistic photodynamic/chemodynamic/immune therapy. The Chl cells with inherent photosynthesis and distinct metabolites are able to ameliorate tumor hypoxia, enhance immune cells infiltration, and stimulate the proliferation and maturation of immune cells. BPNSs loaded on the surface of Chl cells construct a type-II heterojunction with the chlorophyll in Chl cells, which improves the conversion efficiency of light through thoroughly separating photo-excited electrons and holes for ¹O₂ generation and O₂ evolution, respectively. Additionally, the lock between "Lego bricks", Fe³⁺, can both consume glutathione (GSH) and catalyze Fenton reaction with H₂O₂ to generate ·OH, mediating chemodynamic therapy (CDT). Moreover, Chl@BP-Fe also exhibited high biocompatibility and potential biodegradability, guaranteeing high potential for clinic applications of this synergistic photodynamic/chemodynamic/immune therapy.

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.

A bone-targeting drug delivery vehicle of a metal-organic framework conjugate with zoledronate combined with photothermal therapy for tumor inhibition in cancer bone metastasis

Chemotherapy is a conventional treatment method for metastatic bone cancer, but it has limitations, such as lower drug-targeting of bone tissues and serious side effects. Bone metastasis almost always occurs in advanced cancer, and most patients in this period have strong drug resistance, which further worsens the curative effect. To address the above-mentioned difficulties, a drug delivery platform is proposed in this paper that accomplishes the bone-targeting of drugs to efficiently inhibit tumors. First, the anti-cancer drugs 5-fluorouracil (5-Fu) and indocyanine green (ICG) were loaded into a zeolitic imidazolate framework (ZIF-90) to form 5-Fu/ICG@ZIF-90. Polyethylene glycol with zoledronic acid (ZOL) was encapsulated using 5-Fu/ICG@ZIF-90 to synthesize 5-Fu/ICG@ZIF-90-PEG-ZOL nanoparticles, which showed dimensional stability, good thermal stability, and bone-targeting ability. Second, the in vitro anti-cancer activity of the designed platform was investigated using cytotoxicity, apoptosis, live-dead staining, cell cycle, and cell ultrathin section analysis. The results indicated that the nanoparticles inhibited MCF-7 cell activity when chemotherapy was combined with PTT. Finally, H&E staining and TUNEL detection were performed in mouse organs and tumors. The nanoparticles combined with photothermal therapy (PTT) and triggered by near-infrared irradiation induce apoptosis of tumor cells in vivo, displaying a better efficacy of combined chemotherapy and photothermal therapy. Experiments conducted on the 5-Fu/ICG@ZIF-90-PEG-ZOL nanoparticles demonstrated their promising performance for cancer bone metastasis inhibition.

Applications of the ROS-Responsive Thioketal Linker for the Production of Smart Nanomedicines

Reactive oxygen species (ROS)-sensitive drug delivery systems (DDS) specifically responding to altered levels of ROS in the pathological microenvironment have emerged as an effective means to enhance the pharmaceutical efficacy of conventional nanomedicines, while simultaneously reducing side effects. In particular, the use of the biocompatible, biodegradable, and non-toxic ROS-responsive thioketal (TK) functional group in the design of smart DDS has grown exponentially in recent years. In the design of TK-based DDS, different technological uses of TK have been proposed to overcome the major limitations of conventional DDS counterparts including uncontrolled drug release and off-target effects. This review will focus on the different technological uses of TK-based biomaterials in smart nanomedicines by using it as a linker to connect a drug on the surface of nanoparticles, form prodrugs, as a core component of the DDS to directly control its structure, to control the opening of drug-releasing gates or to change the conformation of the nano-systems. A comprehensive view of the various uses of TK may allow researchers to exploit this reactive linker more consciously while designing nanomedicines to be more effective with improved disease-targeting ability, providing novel therapeutic opportunities in the treatment of many diseases.

In-Vitro Co-delivery of Decarbazine and Photosense using Poly lactic-co-glycolic acid nanocarrier for combinational therapy

PLGA (Poly lactic-co-glycolic acid) nanoparticles are in new trend for drug delivery due to their good biodegradability properties. In this study, we have synthesized the PLGA nanoparticles by solvent evaporation method and loaded the decarbazine (DTIC, 5-3,3-(dimethyl-ltriazeno)imidazole-4-carboxamide) and photosense (AlPc4) drug alone as well as combined with two different concentrations i-e 25 nM and 250 nM. No cytotoxicity (viability ∼ 100 %) was observed for different treatment arms either alone or in co-delivery of nano-formulation for Rhabdomyosarcoma (RD) cell culture which showed the biocompatibility of carrier. On comparison, the Photodynamic therapy (PDT) alone showed more significant cell death then the combinational therapy (PDT + chemotherapy) at 2 joule /cm² and 5 joule /cm². Lower doses co-delivery showed light dose dependent toxicity to culture i.e., 0 % death @ 2 joule /cm², ∼ 40 % death @ 5 joule /cm². Gene expressions of four apoptosis related genes (CASP3, CASP9, PARP1 and P53) were quantified by RT-PCR which shows down regulation for all the treatment arms indicating the absence of apoptosis for the cell death during PDT and combinational therapy. It was concluded that apoptosis related genes were down-regulated and morphological changes i.e., swelling and disruption suggest that the mode of cell death was necrosis.

Liposomal cyanine dyes with enhanced nonradiative transition for synergistic phototherapy of tumor

Organic photosensitizers are of great interest in cancer diagnose and treatment such as fluorescence imaging, photodynamic therapy (PDT), and photothermal therapy (PTT). However, their poor aqueous solubility, inadequate photostability and...

Ultrasmall Luminescent Metal Nanoparticles: Surface Engineering Strategies for Biological Targeting and Imaging

In the past decade, ultrasmall luminescent metal nanoparticles (ULMNPs, d < 3 nm) have achieved rapid progress in addressing many challenges in the healthcare field because of their excellent physicochemical properties and biological behaviors. With the sharp shrinking size of large plasmonic metal nanoparticles (PMNPs), the contributions from the surface characteristics increase significantly, which brings both opportunities and challenges in the application-driven surface engineering of ULMNPs toward advanced biological applications. Here, the systematic advancements in the biological applications of ULMNPs from bioimaging to theranostics are summarized with emphasis on the versatile surface engineering strategies in the regulation of biological targeting and imaging performance. The efforts in the surface functionalization strategies of ULMNPs for enhanced disease targeting abilities are first discussed. Thereafter, self-assembly strategies of ULMNPs for fabricating multifunctional nanostructures for multimodal imaging and nanomedicine are discussed. Further, surface engineering strategies of ratiometric ULMNPs to enhance the imaging stability to address the imaging challenges in complicated bioenvironments are summarized. Finally, the phototoxicity of ULMNPs and future perspectives are also reviewed, which are expected to provide a fundamental understanding of the physicochemical properties and biological behaviors of ULMNPs to accelerate their future clinical applications in healthcare.

PEGylated Liposomes Remotely Loaded with the Combination of Doxorubicin, Quinine, and Indocyanine Green Enable Successful Treatment of Multidrug-Resistant Tumors

Multidrug resistance (MDR) of cancer cells remains a major obstacle to favorable outcomes of treatment with many drugs, including doxorubicin. Most of the clinical trials failed to demonstrate the benefit of the drug efflux transporter P-glycoprotein (P-gp) inhibitors to circumvent P-gp-mediated drug resistance in vivo. The present study explored the therapeutic potential of combined treatment with liposomal doxorubicin, P-gp inhibitor quinine, and the photodynamic therapy (PDT) using indocyanine green (ICG) in the adenocarcinoma drug-resistant tumor model. Liposomes were actively co-remotely loaded with doxorubicin and quinine, and ICG was passively adsorbed. The liposomes were characterized by differential scanning calorimetry (DSC) and cryogenic transmission microscopy (Cryo-TEM). We found that quinine impaired the crystalline structure of doxorubicin. In vitro, treatment with single agents themselves was insufficient to inhibit the growth of HT-29 MDR1 cells. However, pegylated liposomal doxorubicin and quinine (PLDQ) significantly diminished HT-29 MDR1 cell survival. Furthermore, survival inhibition intensified by the addition of ICG to the PLDQ (ICG + PLDQ). In vivo, ICG + PLDQ significantly decreased tumor growth when combined with tumor irradiation with NIR light (** p < 0.01). ICG + PLDQ + irradiation was superior to single treatments or combinational treatments without irradiation. These findings suggest that ICG + PLDQ can overcome P-gp-mediated MDR in cancer cells.

Metal-organic framework combined with CaO2 nanoparticles for enhanced and targeted photodynamic therapy

Photodynamic therapy (PDT) has been rapidly developed as an effective therapeutic approach in clinical settings. However, hypoxia seriously limits the effectiveness of PDT. Here, we report a porphyrin-based metal-organic framework combined with hyaluronate-modified CaO₂ nanoparticles (PCN-224-CaO₂-HA) to target and enhance PDT efficacy. CaO₂ reacts with H₂O or weak acid to produce O₂, overcoming the hypoxia problem. Hyaluronate protects CaO₂ and specifically targets the CD44 receptor, which is highly expressed on tumor cell membranes, performing targeted therapy. After PDT treatment in vitro, the survival rates of 4T1 and MCF-7 tumor cells were 14.58% and 22.45%, respectively. The fluorescence imaging showed that PCN-224-CaO₂-HA effectively aggregated in the tumor after 12 h of its intravenous injection into tumor-bearing mice. PCN-224-CaO₂-HA exhibited efficacious tumor growth inhibition via enhanced PDT. Overall, this nanosystem providing in situ oxygen production was successfully used for targeted PDT with a significantly enhanced therapeutic efficacy in vitro and in vivo.

Noncovalent Interactions with PAMAM and PPI Dendrimers Promote the Cellular Uptake and Photodynamic Activity of Rose Bengal: The Role of the Dendrimer Structure

Rose bengal is an anionic dye considered as a potential photosensitizer for anticancer photodynamic therapy. The clinical utility of rose bengal is hampered by its short half-life, limited transmembrane transport, aggregation, and self-quenching; consequently, efficient drug carriers that overcome these obstacles are urgently required. In this study, we performed multilevel in vitro and in silico characterization of interactions between rose bengal and cationic poly(amidoamine) (PAMAM) and poly(propyleneimine) (PPI) dendrimers of the third and fourth generation and assessed the ability of the resultant complexes to modulate the photosensitizing properties of the drug. We focused on explaining the molecular basis of this phenomenon and proved that the generation- and structure-dependent binding of the dye by the dendrimers increases the cellular uptake and production of singlet oxygen and intracellular reactive oxygen species, leading to an increase in phototoxicity. We conclude that the application of dendrimer carriers could enable the design of efficient photodynamic therapies based on rose bengal.

Improved Photophysical Properties of Ionic Material-Based Combination Chemo/PDT Nanomedicine

Herein, a cost-effective and prompt approach to develop ionic material-based combination nanodrugs for cancer therapy is presented. A chemotherapeutic (phosphonium) cation and photodynamic therapeutic (porphyrin) anion are combined using a single step ion exchange reaction. Afterward, a nanomedicine is prepared from this ionic materials-based combination drug using a simplistic strategy of reprecipitation. Improved photophysical characteristics such as a slower nonradiative rate constant, an enhanced phosphorescence emission, a longer lifetime, and a bathochromic shift in absorbance spectra of porphyrin are observed in the presence of a chemotherapeutic countercation. The photodynamic therapeutic activity of nanomedicines is investigated by measuring the singlet oxygen quantum yield using two probes. As compared to the parent porphyrin compound, the synthesized combination material showed a 2-fold increase in the reactive oxygen species quantum yield, due to inhibition of face-to-face aggregation of porphyrin units in the presence of bulky chemotherapeutic ions. The dark cytotoxicity of combination therapy nanomedicines in the MCF-7 (cancerous breast) cell line is also increased as compared to their corresponding parent compounds in vitro. This is due to the high cellular uptake of the combination nanomedicines as compared to that of the free drug. Further, selective toxicity toward cancer cells was acquired by functionalizing nanomedicine with folic acid followed by incubation with MCF-7 and MCF-10A (noncancerous breast). Light toxicity experiments indicate that the synthesized ionic nanomedicine shows a greater cell death than either parent drug due to the improved photophysical properties and effective combination effect. This facile and economical strategy can easily be utilized in the future to develop many other combination ionic nanomedicines with improved photodynamics.

Advances in the Genetically Engineered KillerRed for Photodynamic Therapy Applications

Photodynamic therapy (PDT) is a clinical treatment for cancer or non-neoplastic diseases, and the photosensitizers (PSs) are crucial for PDT efficiency. The commonly used chemical PSs, generally produce ROS through the type II reaction that highly relies on the local oxygen concentration. However, the hypoxic tumor microenvironment and unavoidable dark toxicity of PSs greatly restrain the wide application of PDT. The genetically encoded PSs, unlike chemical PSs, can be modified using genetic engineering techniques and targeted to unique cellular compartments, even within a single cell. KillerRed, as a dimeric red fluorescent protein, can be activated by visible light or upconversion luminescence to execute the Type I reaction of PDT, which does not need too much oxygen and surely attract the researchers’ focus. In particular, nanotechnology provides new opportunities for various modifications of KillerRed and versatile delivery strategies. This review more comprehensively outlines the applications of KillerRed, highlighting the fascinating features of KillerRed genes and proteins in the photodynamic systems. Furthermore, the advantages and defects of KillerRed are also discussed, either alone or in combination with other therapies. These overviews may facilitate understanding KillerRed progress in PDT and suggest some emerging potentials to circumvent challenges to improve the efficiency and accuracy of PDT.

Hybrid Nanoparticles as an Efficient Porphyrin Delivery System for Cancer Cells to Enhance Photodynamic Therapy

Photodynamic therapy (PDT) is a potential non-invasive approach for application in oncological diseases, based on the activation of a photosensitizer (PS) by light at a specific wavelength in the presence of molecular oxygen to produce reactive oxygen species (ROS) that trigger the death tumor cells. In this context, porphyrins are interesting PS because they are robust, have high chemical, photo, thermal, and oxidative stability, and can generate singlet oxygen (1O2). However, porphyrins exhibit low solubility and a strong tendency to aggregate in a biological environment which limits their clinical application. To overcome these challenges, we developed hybrid nanostructures to immobilize 5,10,15,20-tetrakis[(4-carboxyphenyl) thio-2,3,5,6-tetrafluorophenyl] (P), a new third-generation PS. The biological effect of this system was evaluated against bladder cancer (BC) cells with or without light exposition. The nanostructure composed of lipid carriers coated by porphyrin-chitosan (P-HNP), presented a size of ca. 130 nm and low polydispersity (ca. 0.25). The presence of the porphyrin-chitosan (P-chitosan) on lipid nanoparticle surfaces increased the nanoparticle size, changed the zeta potential to positive, decreased the recrystallization index, and increased the thermal stability of nanoparticles. Furthermore, P-chitosan incorporation on nanoparticles increased the stability and enhanced the self-organization of the system and the formation of spherical structures, as observed by small-angle X-ray scattering (SAXS) analysis. Furthermore, the immobilization process maintained the P photoactivity and improved the photophysical properties of PS, minimizing its aggregation in the cell culture medium. In the photoinduction assays, the P-HNP displayed high phototoxicity with IC50 3.2-folds lower than free porphyrin. This higher cytotoxic effect can be correlated to the high cellular uptake of porphyrin immobilized, as observed by confocal images. Moreover, the coated nanoparticles showed mucoadhesive properties interesting to its application in vivo. Therefore, the physical and chemical properties of nanoparticles may be relevant to improve the porphyrin photodynamic activity in BC cells.

Photodynamic therapy of prostate cancer using porphyrinic formulations

Prostate cancer (PCa) is the second most frequent cancer diagnosed in men worldwide. Among the common treatment options, photodynamic therapy (PDT) is being considered a promising local therapy to treat this cancer. Although PDT is an established treatment modality approved for several types of cancer, the low solubility, the reduced tumor selectivity, the absorption in the therapeutic window and the poor clearance from the body of the currently approved photosensitizers (PS) hampers its wide clinical application. In this regard, herein we synthesized three fluorinated porphyrinoid derivatives and entrapped them into polyvinylpyrrolidone (PVP) to prevent their aggregation and preserve their desirable photophysical properties under the physiological environment. In vitro studies revealed the negligible dark cytotoxicity of all PVP formulations (PS1@PVP, PS2@PVP and PS3@PVP) at the tested concentrations (5.0 to 20 μM), but also confirmed the significant photodynamic effect of PS2@PVP and PS3@PVP towards the PCa cell line PC-3, upon red light irradiation at an irradiance of 17.6 mW.cm^-2. To provide insight into the underlying mechanisms of cell death under PDT treatment induced by PS2@PVP and PS3@PVP, their intracellular localization in PC-3 cells was firstly investigated by confocal microscopy. Since both PS2@PVP and PS3@PVP nanoparticles were mainly localized in mitochondria, the involvement of this organelle in PDT-induced apoptosis mediated by both formulations was further explored. Western blot analysis revealed that PDT treatment of PC-3 cells with either PS2@PVP or PS3@PVP resulted in the reduction of the expression level of the anti-apoptotic protein Bcl-2. As the photodamage to Bcl-2 after PDT with PS2@PVP and PS3@PVP was accompanied by the further activation of pro-caspase-3, we assumed that upon irradiation the photogenerated reactive oxygen species (ROS) were able to activate a caspase-dependent apoptotic response as a consequence of a post-mitochondrial event. Taken together, these findings demonstrate that among the tested fluorinated porphyrinoids, PS2@PVP and, particularly, PS3@PVP, are significantly more effective in overall PC-3 cell killing than PS1@PVP, thus highlighting their great potential as therapeutic agents for PCa.

Pyrrole-based photosensitizers for photodynamic therapy — a Thomas Dougherty award paper

Photodynamic therapy (PDT) is a therapeutic modality that uses light to treat malignant or benign diseases. A photosensitizer, light, and oxygen are the three main components needed to generate a cytotoxic effect. Pyrrole-based photosensitizers have been widely used for PDT. Many of the photosensitizers within this class are macrocyclic. This is particularly true for systems that have received regulatory approval or been the subject of clinical trials. However, in recent years, a number of boron dipyrromethanes (BODIPY) have been studied as photosensitizers. Herein, we review examples of some of the most relevant pyrrole-based photosensitizers.

Mitochondria-targeting and ROS-sensitive smart nanoscale supramolecular organic framework for combinational amplified photodynamic therapy and chemotherapy

Owing to their reversibly dynamic features, and the regularity of their architectures, supramolecular organic frameworks (SOFs) have attracted attention as new porous materials. Herein, we propose a smart SOF platform for enhanced photodynamic therapy, where the SOF with a superior mitochondria-targeting capability could be cleaved by reactive oxygen species (ROS) produced by itself for highly enhancing PDT. Moreover, it can further work as a platform for carrying chemo-therapeutic drug doxorubicin for synergistic chemo-photodynamic therapy. The SOF is constructed by combining a tetra-β-cyclodextrin-conjugated porphyrin photosensitizer and a ROS-sensitive thioketal linked adamantane dimer utilizing a host-guest supramolecular strategy. The unique supramolecular framework not only completely resolves the aggregation caused quenching of porphyrin photosensitizers but also endows them with significantly enhanced water-solubility. The in vitro and in vivo results demonstrate that the SOF could be targeted onto mitochondria by confocal imaging, and dissociated by ROS generated by itself, leading to autonomous release of porphyrin photosensitizers and DOX for high anti-cancer activity. It is believed that the strategy using a SOF has the potential of being used to construct versatile agents for combined therapies. STATEMENT OF SIGNIFICANCE: Photosensitizers are the essential element in photodynamic therapy. However, typical photosensitizers commonly encounter poor water-solubility, non-specific tumor-targeting, aggregation-caused quenching (ACQ), which seriously reduce PDT efficacy. A mitochondria-targeting and ROS-sensitive supramolecular organic framework (SOF) is designed for photodynamic therapy in cancer treatment, which could completely overcome the bottleneck in the applications of photosensitizers (PSs). The SOF is constructed by combining a tetra-β-cyclodextrin-conjugated porphyrin photosensitizer and a ROS-sensitive thioketal linked adamantane dimer unit utilizing a host-guest supramolecular strategy. The unique supramolecular framework not only completely resolves the aggregation caused quenching of porphyrin photosensitizers but also endows them with significantly enhanced water-solubility. Moreover, the SOF can be readily functionalized to incorporate the anti-cancer agent Doxorubicin and mitochondria targeting molecules through respective physical encapsulation and host-guest interactions.

Perfluorocarbon nanomaterials for photodynamic therapy

Photodynamic therapy (PDT) is a treatment modality in which a photosensitizer is irradiated with light, producing reactive oxygen species, often via energy transfer with oxygen. As it is common for tumors to be hypoxic, methods to deliver photosensitizer and oxygen are desirable. One such approach is the use of perfluorocarbons, molecules in which all C-H bonds are replaced with C-F bonds, to co-deliver oxygen because of the high solubility of gases in perfluorocarbons. This review highlights the benefits and limitations of several fluorinated nanomaterial architectures for use in PDT.