Tumor-targeting, enzyme-activated nanoparticles for simultaneous cancer diagnosis and photodynamic therapy

Optimized strategies of ROS-based nanodynamic therapies for tumor theranostics

Reactive oxygen species (ROS) play a crucial role in regulating the metabolism of tumor growth, metastasis, death and other biological processes. ROS-based nanodynamic therapies (NDTs) are becoming attractive due to non-invasive, low side effects and tumor-specific advantages. NDTs have rapidly developed into numerous branches, such as photodynamic therapy, chemodynamic therapy, sonodynamic therapy and so on. However, the complexity of the tumor microenvironment and the limitations of existing sensitizers have greatly restricted the therapeutic effects of NDTs, which heavily rely on ROS levels. To address the limitations of NDTs, various strategies have been developed to increase ROS yield, which is an urgent aspect for the positive development of NDTs. In this review, the nanodynamic potentiation strategies in terms of unique properties and universalities of NDTs are comprehensively outlined. We mainly summarize the current dilemmas faced by each NDT and the respective solutions. Meanwhile, the NDTs universalities-based potentiation strategies and NDTs-based combined treatments are elaborated. Finally, we conclude with a discussion of the key issues and challenges faced in the development and clinical transformation of NDTs.

Photodynamic Therapy: From the Basics to the Current Progress of N-Heterocyclic-Bearing Dyes as Effective Photosensitizers

Photodynamic therapy, an alternative that has gained weight and popularity compared to current conventional therapies in the treatment of cancer, is a minimally invasive therapeutic strategy that generally results from the simultaneous action of three factors: a molecule with high sensitivity to light, the photosensitizer, molecular oxygen in the triplet state, and light energy. There is much to be said about each of these three elements; however, the efficacy of the photosensitizer is the most determining factor for the success of this therapeutic modality. Porphyrins, chlorins, phthalocyanines, boron-dipyrromethenes, and cyanines are some of the N-heterocycle-bearing dyes' classes with high biological promise. In this review, a concise approach is taken to these and other families of potential photosensitizers and the molecular modifications that have recently appeared in the literature within the scope of their photodynamic application, as well as how these compounds and their formulations may eventually overcome the deficiencies of the molecules currently clinically used and revolutionize the therapies to eradicate or delay the growth of tumor cells.

BODIPY as a Multifunctional Theranostic Reagent in Biomedicine: Self-Assembly, Properties, and Applications

The use of boron dipyrromethene (BODIPY) in biomedicine is reviewed. To open, its synthesis and regulatory strategies are summarized, and inspiring cutting-edge work in post-functionalization strategies is highlighted. A brief overview of assembly model of BODIPY is then provided: BODIPY is introduced as a promising building block for the formation of single- and multicomponent self-assembled systems, including nanostructures suitable for aqueous environments, thereby showing the great development potential of supramolecular assembly in biomedicine applications. The frontier progress of BODIPY in biomedical application is thereafter described, supported by examples of the frontiers of biomedical applications of BODIPY-containing smart materials: it mainly involves the application of materials based on BODIPY building blocks and their assemblies in fluorescence bioimaging, photoacoustic imaging, disease treatment including photodynamic therapy, photothermal therapy, and immunotherapy. Lastly, not only the current status of the BODIPY family in the biomedical field but also the challenges worth considering are summarized. At the same time, insights into the future development prospects of biomedically applicable BODIPY are provided.

Novel nanoparticles prepared from isothiocyanate derivatives for phototherapy of tumor

Phototherapy is a new method to treat tumor, including photodynamic therapy (PDT) and photothermal therapy (PTT). However, the GSH in tumor cells could deplete ROS produced by photosensitizers, resulting in inadequate PDT. Isothiocyanate not only is a new type of anti-tumor drug, but also may combine with GSH, increasing the content of intracellular ROS and improving PDT effect. Here we synthesized a kind of water-soluble nanoparticles (BN NPs) parceling BODIPY-I-35 up with mPEG-ITC and lecithin. mPEG-ITC can react with GSH in tumor cells to reduce the consumption of ROS. BN NPs can be used as vectors to deliver drugs to tumor sites. Under 808 nm laser irradiation, BN NPs solution increased 13 °C within 10 min, indicating that BN NPs had superb photothermal performance. In vitro experiments, low dose BN NPs showed satisfactory PDT and PTT effects, and the cell viability of MCF-7 cell was only 13%. In vivo, BN NPs with excellent biocompatibility showed favorable phototherapy effect and tumor was effectively inhibited. Fluorescence imaging could present the long retention effect of BN NPs in tumor locations. In conclusion, the BN NPs showed the effect of enhancing phototherapy and provided a remarkable application prospect in the phototherapy of tumor cells.

D-A-D organic small molecules with AIE effect for fluorescence imaging guided photothermal therapy

Near infrared (NIR) fluorescent organic molecules as fluorescent probes accurately guide photothermal therapy as a potential antitumor method. However, the aggregation and quenching of organic fluorescent molecules and poor tissue permeability greatly limit their therapeutic effect and clinical transformation. In this paper, with a D-A-D structure as the molecular skeleton, cyclopentadithiophene (CPDT) as the donor (D), diketopyrrolopyrrole (DPP) as the acceptor (A), and long-chain isooctane as the shielding unit, organic fluorescent small molecules with a strong absorption band and bright NIR-II emission were synthesized. Then, tetraphenylethylene (TPE) molecules with typical AIE structure characteristics were introduced on both sides of the organic fluorescent small molecules, and an organic small molecular fluorophore (TDA) with AIE characteristics and the photothermal effect was designed. Through a series of experimental characterization techniques, it is proved that TDA NPs have good biocompatibility and tissue permeability, and can accurately locate the tumor location through NIR-II fluorescence imaging to achieve local photothermal treatment of tumors.

Insights on the Dynamic Innovative Tumor Targeted-Nanoparticles-Based Drug Delivery Systems Activation Techniques

Anti-cancer conventional chemotherapeutic drugs novel formula progress, nowadays, uses nano technology for targeted drug delivery, specifically tailored to overcome therapeutic agents' delivery challenges. Polymer drug delivery systems (DDS) play a crucial role in minimizing off-target side effects arising when using standard cytotoxic drugs. Using nano-formula for targeted localized action, permits using larger effective cytotoxic doses on a single special spot, that can seriously cause harm if it was administered systemically. Therefore, various nanoparticles (NPs) specifically have attached groups for targeting capabilities, not seen in bulk materials, which then need activation. In this review, we will present a simple innovative, illustrative, in a cartoon-way, enumeration of NP anti-cancer drug targeting delivery system activation-types. Area(s) covered in this review are the mechanisms of various NP activation techniques.

Hyaluronic Acid within Self-Assembling Nanoparticles: Endless Possibilities for Targeted Cancer Therapy

Self-assembling nanoparticles (SANPs) based on hyaluronic acid (HA) represent unique tools in cancer therapy because they combine the HA targeting activity towards cancer cells with the advantageous features of the self-assembling nanosystems, i.e., chemical versatility and ease of preparation and scalability. This review describes the key outcomes arising from the combination of HA and SANPs, focusing on nanomaterials where HA and/or HA-derivatives are inserted within the self-assembling nanostructure. We elucidate the different HA derivatization strategies proposed for this scope, as well as the preparation methods used for the fabrication of the delivery device. After showing the biological results in the employed in vivo and in vitro models, we discussed the pros and cons of each nanosystem, opening a discussion on which approach represents the most promising strategy for further investigation and effective therapeutic protocol development.

An AIPH-decorated semiconducting nanoagonist for NIR-II light-triggered photothermic/thermodynamic combinational therapy

A multifunctional semiconducting nanoagonist with high photothermic conversion efficiency (86.2%) and alkyl radical generation ability was developed. The nanoagonist demonstrated excellent anticancer performance through NIR-II light-triggered photothermic/thermodynamic combinational therapy both in vitro and in vivo.

The photodynamic/photothermal synergistic therapeutic effect of BODIPY-I-35 liposomes with urea

Phototherapy is a new treatment means for cancer which can reduce the side effects of traditional cancer treatments to humans. Urea is a naturally occurring metabolite in the human body. Some studies have shown that it can inhibit the proliferation of tumor cells and cause oxidative stress. In order to explore the application of urea in enhancing the phototherapy effect, we synthesized a new structure photosensitizer (BODIPY-I-35) with good phototherapeutic effect and encapsulated it in liposomes. Compared with free BODIPY-I-35, water-soluble nanoliposomes (LipoBOD) produced a huge redshift (> 122 nm) of fluorescence emission in solution. When LipoBOD was irradiated with 808 nm laser (1 W/cm²) for 10 min, the temperature contrast increased by 20 °C, which was 4 times higher than free BODIPY-I-35. Confocal microscopy showed appreciable accumulation of LipoBOD in HeLa cells. In addition, when LipoBOD was incubated with urea in HeLa cells, we found that urea not only obviously enhanced the production of ROS, but also increased the apoptosis of HeLa cells. The synergistic effect of LipoBOD (20 μg/mL, at BODIPY-I-35-eq) with urea (250 mM) showed significantly higher phototoxicity than LipoBOD alone. Low dose can reduce the cell viability to 10%. Therefore, we have obtained an effective method of using urea to enhance the phototherapy effect.

Tumor Microenvironment-Responsive Nanomaterials as Targeted Delivery Carriers for Photodynamic Anticancer Therapy

Photodynamic therapy (PDT), as an alternative approach to treat tumors through reactive oxygen species (ROS) produced by the activated photosensitizers (PS) upon light irradiation, has attracted wide attention in recent years due to its low invasive and highly efficient features. However, the low hydrophilicity and poor targeting of PS limits the clinical application of PDT. Stimuli-responsive nanomaterials represent a major class of remarkable functional nanocarriers for drug delivery. In particular, tumor microenvironment-responsive nanomaterials (TMRNs) can respond to the special pathological microenvironment in tumor tissues to release the loaded drugs, that allows them to control the release of PS within tumor tissues. Recent studies have demonstrated that TMRNs can achieve the targeted release of PS at tumor sites, increase the concentration of PS in tumor tissues, and reduce side effects of PDT. Hence, in the present paper, we review TMRNs, mainly including pH-, redox-, enzymes-, and hypoxia-responsive smart nanomaterials, and focus on the application of these smart nanomaterials as targeted delivery carriers of PS in photodynamic anticancer therapy, to further boost the development of PDT in tumor therapy.

A targeting black phosphorus nanoparticle based immune cells nano-regulator for photodynamic/photothermal and photo-immunotherapy

Photo-immunotherapy is a novel therapeutic approach against malignant tumors with minimal invasiveness. Herein, a targeting multifunctional black phosphorus (BP) nanoparticle, modified by PEGylated hyaluronic acid (HA), was designed for photothermal/photodynamic/photo-immunotherapy. In vitro and in vivo assays indicated that HA-BP nanoparticles possess excellent biocompatibility, stability, and sufficient therapeutic efficacy in the combined therapy of photothermal therapy (PTT) and photodynamic therapy (PDT) for cancer therapy. Moreover, the results of in vitro showed that HA-BP down-regulated the expression of CD206 (M2 macrophage marker) by 42.3% and up-regulated the ratio of CD86（M1 macrophage marker）by 59.6%, indicating that HA-BP nanoparticles have functions in remodeling tumor associated macrophages (TAMs) phenotype (from pro-tumor M2 TAMs to anti-tumor M1 macrophages). Fluorescence (FL) and photoacoustic (PA) multimodal imaging confirmed the selective accumulation of HA-BP in tumor site via both CD44⁺ mediated active targeting and passive EPR effect. In vitro and in vivo studies suggested that the combined therapy of PDT, PTT and immunotherapy using HA-BP could not only significantly inhibit original tumor but also induce immunogenic cell death (ICD) and release Damage-associated molecular patterns (DAMPs), which could induce maturation of dendritic cells (DCs) and activate effector cells that robustly evoke the antitumor immune responses for cancer treatment. This study expands the biomedical application of BP nanoparticles and displays the potential of modified BP as a multifunctional therapeutic platform for the future cancer therapy.

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Novel HA-BP NPs were synthesized for photothermal/photodynamic/photo-immunotherapy.

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HA-BP NPs with size around 50 nm possess remarkable enhancement of tumor targeting and accumulation ability.

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HA-BP NPs could promote M2 to M1 macrophage polarization and further enhance invasion of activated CD4⁺ and CD8⁺ T cells.

An APN-activated NIR photosensitizer for cancer photodynamic therapy and fluorescence imaging

Photodynamic therapy has been developed as a prospective cancer treatment in recent years. Nevertheless, conventional photosensitizers suffer from lacking recognition and specificity to tumors, which causing severe side effects to normal tissues, while the enzyme-activated photosensitizers are capable of solving these conundrums due to high selectivity towards tumors. APN (Aminopeptidase N, APN/CD13), a tumor marker, has become a crucial targeting substance owing to its highly expressed on the cell membrane surface in various tumors, which has become a key point in the research of anti-tumor drug and fluorescence probe. Based on it, herein an APN-activated near-infrared (NIR) photosensitizer (APN-CyI) for tumor imaging and photodynamic therapy has been firstly developed and successfully applied in vitro and in vivo. Studies showed that APN-CyI could be activated by APN in tumor cells, hydrolyzed to fluorescent CyI-OH, which specifically located in mitochondria in cancer cells and exhibited a high singlet oxygen yield under NIR irradiation, and efficiently induced cancer cell apoptosis. Dramatically, the in vivo assays on Balb/c mice showed that APN-CyI could achieve NIR fluorescence imaging (λ_em = 717 nm) for endogenous APN in tumors and possessed an efficient tumor suppression effect under NIR irradiation.

Activatable Phototheranostic Materials for Imaging-Guided Cancer Therapy

Cancer theranostics, which combines diagnostic and therapeutic effects into one entity, holds promise in precision medicine. Conventional theranostic agents possess always-on imaging signals and cytotoxic effects and thus often encounter poor selectivity or specificity in cancer treatment. To tackle this issue, activatable phototheranostic materials (PMs) have been developed to simultaneously and specifically turn on their diagnostic signals (fluorescence/self-luminescence/photoacoustic signals) and photothermal/photodynamic effects in response to cancer hallmarks. This Review summarizes the recent progress in the design, synthesis and proof-of-concept applications of activatable PMs. The molecular engineering strategy to increase tumor accumulation and enhance treatment efficacy are highlighted. Current challenges and future perspectives in this emerging field are also discussed.

Nanoparticle-based drug delivery systems for controllable photodynamic cancer therapy

Compared with the traditional treatment, photodynamic therapy (PDT) in the treatment of malignant tumors has the advantages of less damage to normal tissues, quick therapeutic effect, and ability to repeat treatments to the same site. However, most of the traditional photosensitizers (PSs) have severe skin photosensitization, poor tumor targeting, and low therapeutic effect in hypoxic tumor environment, which limit the application of PDT. Nanoparticle-based drug delivery systems can improve the targeting of PSs and release drugs with controllable photoactivity at predetermined locations, so as to achieve desired therapeutic effects with minimal side-effects. The present review summarizes the current nanoparticle platforms for PDT, and offers the description of different strategies including tumor-targeted delivery, controlled-release of PSs and the triggered photoactivity to achieve controllable PDT by nanoparticle-based drug delivery systems. The challenges and prospects for further development of intelligent PSs for PDT are also discussed.

GSH-Activatable NIR Nanoplatform with Mitochondria Targeting for Enhancing Tumor-Specific Therapy

Developing smart photosensitizers that are sensitive to tumor-specific signals for minimal side effects and enhanced antitumor efficacy is a tremendous challenge for tumor phototherapies. Herein, we construct a nanoplatform with glutathione (GSH)-activatable and mitochondria-targeted pro-photosensitizer encapsulated by ultrasensitive pH-responsive polymer for achieving imaging-guided tumor-specific photodynamic therapy (PDT). The GSH-activatable pro-photosensitizer, di-cyanine (DCy7), has been synthesized where two cyanine moieties are covalently conjugated by a disulfide bond, and the hydrophobic DCy7 is further encapsulated with an amphiphilic pH-responsive diblock copolymer POEGMA-b-PDPA to form P@DCy7 nanoparticles. Upon endocytosis by cancer cells, P@DCy7 nanoparticles dissociate at endosome first and then DCy7 is released to cytoplasm and subsequently activated by the high concentration of GSH, finally targets mitochondria for organelle-targeted PDT. Moreover, intracellular antioxidant GSH is consumed during the activation procedure that is beneficial to efficient PDT. These P@DCy7 nanoparticles display selective phototoxicity against tumor cells (HepG2 or 4T1 cells) over normal cells (BEAS-2B cells) in vitro, and their GSH-activatable enhanced PDT efficacy is further confirmed in tumor-bearing mice. Thus, P@DCy7 nanoparticles allow for accurate and highly efficient PDT with minimal side effects, providing an attractive nanoplatform for organelle-targeted precise PDT.

Boron Dipyrromethene Nano-Photosensitizers for Anticancer Phototherapies

As traditional phototherapy agents, boron dipyrromethene (BODIPY) photosensitizers have attracted increasing attention due to their high molar extinction coefficients, high phototherapy efficacy, and excellent photostability. After being formed into nanostructures, BODIPY-containing nano-photosensitizers show enhanced water solubility and biocompatibility as well as efficient tumor accumulation compared to BODIPY molecules. Hence, BODIPY nano-photosensitizers demonstrate a promising potential for fighting cancer. This review contains three sections, classifying photodynamic therapy (PDT), photothermal therapy (PTT), and the combination of PDT and PTT based on BODIPY nano-photosensitizers. It summarizes various BODIPY nano-photosensitizers, which are prepared via different approaches including molecular precipitation, supramolecular interactions, and polymer encapsulation. In each section, the design strategies and working principles of these BODIPY nano-photosensitizers are highlighted. In addition, the detailed in vitro and in vivo applications of these recently developed nano-photosensitizers are discussed together with future challenges in this field, highlighting the potential of these promising nanoagents for new tumor phototherapies.

Functional black phosphorus nanosheets for mitochondria-targeting photothermal/photodynamic synergistic cancer therapy

A mitochondria-targeting nanosystem, BP@PDA–Ce6&TPP NSs, has been constructed, and exhibit excellent performance in imaging-guided synergistic photothermal and photodynamic cancer therapy.

Organelle-targeting nanosystems are envisioned as promising tools for phototherapy, which can generate heat or reactive oxygen species (ROS) induced cytotoxicity in the targeted location but leave the surrounding biological tissues undamaged. In this work, an imaging-guided mitochondria-targeting photothermal/photodynamic nanosystem has been developed on the basis of functionalized black phosphorus (BP) nanosheets (NSs). In the nanosystem, BP NSs are coated with polydopamine (PDA) and then covalently linked with both chlorin e6 (Ce6) and triphenyl phosphonium (TPP) through carbodiimide reaction between the amino group and the carboxyl group, forming BP@PDA–Ce6&TPP NSs. Due to the strong absorbance of BP@PDA in the near-infrared region and the highly efficient ROS generation of Ce6, the as-prepared nanosystem with mitochondria-targeting capacity (TPP moiety) shows remarkably enhanced efficiency in cancer cell killing. Combined photothermal and photodynamic therapy is implemented and monitored by in vivo fluorescence imaging, achieving excellent performance in inhibiting tumor growth. This study presents a novel nanotheranostic agent for mitochondria-targeting phototherapy, which may open new horizons for biomedicine.

Nano-black phosphorus for combined cancer phototherapy: recent advances and prospects

Black phosphorus (BP), emerging as a new member of two-dimensional nanomaterials, has attracted growing research interests for its amazing photoelectric properties and promising application in electronic devices. Recently, BP has been confirmed to be a desirable candidate for phototherapy against cancer, including photothermal therapy and photodynamic therapy. By regulating the number of layers, the bandgap of BP nanosheets (NSs) can be finely tuned to present near infrared light triggered phototherapeutic behaviors. Furthermore, the exfoliated nano-sized BP also exhibits excellent tumor-targeting property as a nanomedicine via the enhanced permeability and retention effect. With biodegradable nature and outstanding therapeutic performance, BP is highly expected to be developed as novel anti-cancer agents as well as a potential carrier for advanced cancer theranostics. In this review, on the basis of summarizing the recent advances of BP in biomedical applications, the size and layer effects of BP on its targeting effect and phototherapeutic performance are discussed. Then, the rationally designed multifunctional nanoplatforms based on BP are introduced. And, the remaining challenges and prospects of nano-BP for clinic applications against cancer are discussed and outlooked.

Organic Dye Based Nanoparticles for Cancer Phototheranostics

Phototheranostics, which simultaneously combines photodynamic and/or photothermal therapy with deep-tissue diagnostic imaging, is a promising strategy for the diagnosis and treatment of cancers. Organic dyes with the merits of strong near-infrared absorbance, high photo-to-radical and/or photothermal conversion efficiency, great biocompatibility, ready chemical structure fine-tuning capability, and easy metabolism, have been demonstrated as attractive candidates for clinical phototheranostics. These organic dyes can be further designed and fabricated into nanoparticles (NPs) using various strategies. Compared to free molecules, these NPs can be equipped with multiple synergistic functions and show longer lifetime in blood circulation and passive tumor-targeting property via the enhanced permeability and retention effect. In this article, the recent progress of organic dye-based NPs for cancer phototheranostic applications is summarized, which extends the anticancer arsenal and holds promise for clinical uses in the near future.

Low density lipoprotein modified silica nanoparticles loaded with docetaxel and thalidomide for effective chemotherapy of liver cancer

In the present study, we successfully developed a docetaxel (DTX) and thalidomide (TDD) co-delivery system based on low density lipoprotein (LDL) modified silica nanoparticles (LDL/SLN/DTX/TDD). By employing the tumor homing property of LDL and the drug-loading capability of silica nanoparticles, the prepared LDL/SLN/DTX/TDD was expected to locate and specifically deliver the loaded drugs (DTX and TDD) to achieve effective chemotherapy of liver cancer. In vitro analysis revealed that nano-sized LDL/SLN/DTX/TDD with decent drug loading capabilities was able to increase the delivery efficiency by targeting the low density lipoprotein receptors, which were overexpressed on HepG2 human hepatocellular liver carcinoma cell line, which exerted better cytotoxicity than unmodified silica nanoparticles and free drugs. In vivo imaging and anti-cancer assays also confirmed the preferable tumor-homing and synergetic anti-cancer effects of LDL/SLN/DTX/TDD.

Photosensitizer synergistic effects: D-A-D structured organic molecule with enhanced fluorescence and singlet oxygen quantum yield for photodynamic therapy

Novel photosensitizers have been developed with high ¹O₂ quantum yields and strong fluorescence for cancer diagnosis and PDT.

The development of photosensitizers with high fluorescence intensity and singlet oxygen (¹O₂) quantum yields (QYs) is of great importance for cancer diagnosis and photodynamic therapy (PDT). Diketopyrrolopyrrole (DPP) and boron dipyrromethene (BODIPY) are two kinds of building block with great potential for PDT. Herein, a novel donor–acceptor–donor (D–A–D) structured organic photosensitizer DPPBDPI with a benzene ring as a π bridge linking DPP and BODIPY has been designed and synthesized. The results indicate that the combination of DPP with BODIPY can simultaneously increase the fluorescence QY (5.0%) and the ¹O₂ QY (up to 80%) significantly by the synergistic effect of the two photosensitizers. By nanoprecipitation, DPPBDPI can form uniform nanoparticles (NPs) with a diameter of less than 100 nm. The obtained NPs not only exhibit high photo-toxicity, but also present negligible dark toxicity towards HeLa cells, demonstrating their excellent photodynamic therapeutic efficacy. In vivo fluorescence imaging shows that DPPBDPI NPs can target the tumor site quickly with the enhanced permeability and retention (EPR) effect and can effectively inhibit tumor growth using photodynamic therapy even with low doses (0.5 mg kg^–1). The enhanced imaging and photodynamic performance of DPPBDPI suggest that the synergistic effect of DPP and BODIPY provides a novel theranostic platform for cancer diagnosis and photodynamic therapy.

Zinc(II) Metalated Porphyrins as Photothermogenic Photosensitizers for Cancer Photodynamic/Photothermal Synergistic Therapy

Porphyrin derivatives are the first-generation photosensitizers, and to design a strong near-infrared (NIR)-absorbing porphyrin with good water solubility is highly desired for better therapeutic effect to treat tumors. Herein, three new porphyrin derivatives, 5,10,15,20-tetrakis(3,4-dimethoxyphenyl) porphyrin (P1), 5,10,15,20-tetrakis(3,4-dimethoxyphenyl) zinc porphyrin (ZnP1), and 5,15-bis(3,4-dimethoxyphenyl)-10,20-bis((4-methoxyphenyl)ethynyl) zinc porphyrin (ZnP2) have been synthesized. Among them, ZnP2 shows the longest and most intensive Q-bands in the near-infrared (NIR) region, as it endows the strongest light-harvesting capability and deepest tumor tissue penetration. The three porphyrin derivatives were prepared into nanoparticles (NPs) via nanoprecipitation method, and the NPs exhibit good water dispersibility and passive tumor-targeting property through enhanced permeability and retention effect. Furthermore, these NPs demonstrate both photodynamic and photothermal effects. Through a systematic study of the singlet oxygen quantum yield and cytotoxicity of P1, ZnP1, and ZnP2 NPs in vitro on Hela cells, it is found that ZnP2 shows the highest singlet oxygen quantum yield (79%), and its NPs show the best therapeutic efficacy in vitro. In vivo experiments disclosed that ZnP2 NPs present high phototoxicity, low dark toxicity, and excellent biocompatibility, and could be used as promising photothermogenic photosensitizer for cancer treatment.

A fullerene-rhodamine B photosensitizer with pH-activated visible-light absorbance/fluorescence/photodynamic therapy

A heavy-atom-free photosensitizer (C₆₀-RB) with pH-activable visible-light absorbance enhancement, fluorescence turn-on and triplet excited state generation was designed for tumor bioimaging and photodynamic therapy.

A selenophene substituted diketopyrrolopyrrole nanotheranostic agent for highly efficient photoacoustic/infrared-thermal imaging-guided phototherapy

A selenophene substituted diketopyrrolopyrrole based nanotheranostic agent has been synthesized for highly efficient photoacoustic/infrared-thermal imaging-guided tumor phototherapy.

Surface Modified Ti3C2 MXene Nanosheets for Tumor Targeting Photothermal/Photodynamic/Chemo Synergistic Therapy

Ti₃C₂ MXene is a new two-dimensional material exhibiting a variety of novel properties including good photothermal effect, and the capability of Ti₃C₂ for multimodal tumor therapy is in urgent need of development. Herein, ultrathin Ti₃C₂ MXene nanosheets (∼100 nm) have been synthesized by supplying additive Al³⁺ to avoid Al loss and employed as a photothermal/photodynamic agent for cancer therapy. The as-obtained nanosheets exhibit outstanding mass extinction coefficient (28.6 Lg^-1 cm^-1 at 808 nm), superior photothermal conversion efficiency (∼58.3%), and effective singlet oxygen generation (¹O₂) upon 808 nm laser irradiation. Based on these Ti₃C₂ nanosheets, a multifunctional nanoplatform (Ti₃C₂-DOX) is established via layer-by-layer surface modification with doxorubicin (DOX) and hyaluronic acid (HA). In vitro and in vivo experiments disclose that Ti₃C₂-DOX shows enhanced biocompatibility, tumor specific accumulation, and stimuli-responsive drug release behavior and achieve effective cancer cell killing and tumor tissue destruction through photothermal/photodynamic/chemo synergistic therapy.

BODIPY Derivatives for Photodynamic Therapy: Influence of Configuration versus Heavy Atom Effect

Heavy atom effect and configuration are important for BODIPY derivatives to generate singlet oxygen (¹O₂) for photodynamic therapy. Herein, a series of BODIPY derivatives with different halogens were synthesized. ¹O₂ quantum yields (QYs) and MTT assay confirm that incorporation of more heavy atoms onto dimeric BODIPY cannot effectively enhance the ¹O₂ QYs. Rather, the dark toxicity increases. This phenomenon can be attributed to the competition of heavy atom effect and configuration of dimeric BODIPY. In addition the BODIPY derivative with two iodine atoms (BDPI) owns the highest ¹O₂ QYs (73%) and the lowest phototoxicity IC₅₀ (1 μM). Furthermore, an in vivo study demonstrates that BDPI NPs can effectively inhibit tumor growth and can be used as a promising threanostic agent for photodynamic therapy in clinic.

Cancer-Associated, Stimuli-Driven, Turn on Theranostics for Multimodality Imaging and Therapy

Advances in bioinformatics, genomics, proteomics, and metabolomics have facilitated the development of novel anticancer agents that have decreased side effects and increased safety. Theranostics, systems that have combined therapeutic effects and diagnostic capabilities, have garnered increasing attention recently because of their potential use in personalized medicine, including cancer-targeting treatments for patients. One interesting approach to achieving this potential involves the development of cancer-associated, stimuli-driven, turn on theranostics. Multicomponent constructs of this type would have the capability of selectively delivering therapeutic reagents into cancer cells or tumor tissues while simultaneously generating unique signals that can be readily monitored under both in vitro and in vivo conditions. Specifically, their combined anticancer activities and selective visual signal respond to cancer-associated stimuli, would make these theranostic agents more highly efficient and specific for cancer treatment and diagnosis. This article focuses on the progress of stimuli-responsive turn on theranostics that activate diagnostic signals and release therapeutic reagents in response to the cancer-associated stimuli. The present article not only provides the fundamental backgrounds of diagnostic and therapeutic tools that have been widely utilized for developing theranostic agents, but also discusses the current approaches for developing stimuli-responsive turn on theranostics.

Enzyme-responsive peptide dendrimer-gemcitabine conjugate as a controlled-release drug delivery vehicle with enhanced antitumor efficacy

Stimuli-responsive peptide dendrimer-drug conjugates have presented significant potential for cancer therapy. To develop an effective nanoscale chemotherapeutic prodrug, we developed a novel enzyme-responsive PEGylated lysine peptide dendrimer-gemcitabine conjugate (Dendrimer-GEM) based nanoparticle via the highly efficient click reaction. Owing to the glycyl phenylalanyl leucyl glycine tetra-peptide (GFLG) as an enzyme-cleavable linker to conjugate gemcitabine (GEM), the prepared nanoparticles were able to release drug significantly faster in the tumor cellular environments, which specifically contains secreted Cathepsin B, quantifiably more than 80% GEM was released with Cathepsin B compared to the condition without Cathepsin B at 24h. This nanoparticle demonstrated enhanced antitumor efficacy in a 4T1 murine breast cancer model without obvious systemic toxicity, resulting in significantly suppressed relative tumor volumes (86.17±38.27%) and a 2-fold higher value of tumor growth inhibition (∼90%) than GEM·HCl treatment. These results suggest that the PEGylated peptide dendrimer-gemcitabine conjugate can be an effective antitumor agent for breast cancer therapy. Statement of Significance We found that the functionalized dendrimer based nanoscale drug delivery vehicles exhibited enhanced therapeutic indexes and reduced toxicity as compared to the free drug gemcitabine. Compared with current nanoparticles, such as dendritic anticancer drug delivery systems, the new design was capable of self-assembling into nanoscale particles with sizes of about 80-110nm, which is suitable as antitumor drug delivery vehicle due to the potential longer intravascular half-life and higher accumulation in tumor tissue via EPR effect. Owing to the optimized architecture, the system was given the enzyme-responsive drug release feature, and showed excellent antitumor activity on the 4T1 breast tumor model due to the evidences from tumor growth curves, immunohistochemical analysis and confocal laser scanning microscopy. Meanwhile, no significant side effect was observed by histological analysis. This study demonstrated that PEGylated peptide dendritic architecture may be used as efficient and safe nanoscale drug delivery vehicle for cancer therapy.

FDPP–HA as a theranostic agent for cancer-targeted fluorescence imaging and photodynamic therapy

FDPP–HA was synthesized for tumor targeting photodynamic therapy. All experiments reveal that FDPP–HA presents excellent biocompatibility, high phototoxicity and specific targeted fluorescence imaging properties.

An aza-BODIPY photosensitizer for photoacoustic and photothermal imaging guided dual modal cancer phototherapy

A novel NIR absorbing aza-BODIPY photosensitizer with high ¹O₂ quantum yield and excellent photothermal conversion efficiency was designed for synergistic phototherapy.

Coordination-Induced Assembly of Intelligent Polysaccharide-Based Phototherapeutic Nanoparticles for Cancer Treatment

Smart polysaccharide-based anticancer phototherapeutic nanoparticles are prepared via a coordination-induced assembly process. Upon irradiated with a near infrared laser, the nanoparticles are not only able to simultaneously generate reactive oxygen species and hyperthermia that ablate tumors, but also possess tumor microenvironment-responsive off/on near infrared fluorescence and enhancement in photothermal effect, making them promising theranostic platform of cancer.

Camptothecin-Polysaccharide Co-assembly and Its Controlled Release

β-Cyclodextrin modified camptothecin (CPT-CD) was synthesized through esterification reaction and "click chemistry" to greatly improve the solubility of CPT in aqueous solution, and then, a supramolecular nanoparticle was constructed by strong noncovalent interaction between β-cyclodextrin and adamantane and amphiphilic interaction by simply mixing CPT-CD and adamantane modified hyaluronic acid (HA-ADA) together. The obtained nanoparticle had a hydrophilic HA shell, which could target and recognize HA receptors overexpressed on the surface of cancer cells, and a hydrophobic CPT core, which could protect CPT from hydrolyzation. The results of cytotoxicity experiments showed that the nanoparticle we have designed in this work exhibited similar anticancer activities to, but with much lower side effects than, the commercial chemotherapeutic drug CPT in vitro. We believe that this work might provide a strategy for improving the treatment performance of CPT in laboratory and clinical settings.

A biomimicking and electrostatic self-assembly strategy for the preparation of glycopolymer decorated photoactive nanoparticles

A biomimicking and electrostatic self-assembly strategy for the preparation of glycopolymer decorated photoactive nanoparticles.