NIR-Triggered Multifunctional and Degradable Nanoplatform Based on an ROS-Sensitive Block Copolymer for Imaging-Guided Chemo-Phototherapy

Spatiotemporal Control of Biology: Synthetic Photochemistry Toolbox with Far-Red and Near-Infrared Light

The complex network of naturally occurring biological pathways motivates the development of new synthetic molecules to perturb and/or detect these processes for fundamental research and clinical applications. In this context, photochemical tools have emerged as an approach to control the activity of drug or probe molecules at high temporal and spatial resolutions. Traditional photochemical tools, particularly photolabile protecting groups (photocages) and photoswitches, rely on high-energy UV light that is only applicable to cells or transparent model animals. More recently, such designs have evolved into the visible and near-infrared regions with deeper tissue penetration, enabling photocontrol to study biology in tissue and model animal contexts. This Review highlights recent developments in synthetic far-red and near-infrared photocages and photoswitches and their current and potential applications at the interface of chemistry and biology.

A multifunctional platinum(IV) and cyanine dye-based polyprodrug for trimodal imaging-guided chemo-phototherapy

Imaging-guided chemo-phototherapy based on a single nanoplatform has a great significance to improve the efficiency of cancer therapy and diagnosis. However, high drug content, no burst release and real-time tracking of nanodrugs are the three main challenges for this kind of multifunctional nanotheranostics. In this work, we developed an innovative theranostic nanoplatform based on a Pt(IV) prodrug and a near-infrared (NIR) photosensitizer. A Pt(IV) prodrug and a cyanine dye (HOCyOH, Cy) were copolymerized and incorporated into the main chain of a polyprodrug (PCPP), which self-assembled into nanoparticles (NPs) with ∼27.61% Cy loading and ∼9.37% Pt loading, respectively. PCPP NPs enabled reduction-triggered backbone cleavage of polyprodrugs and bioactive Pt(II) release; Cy could be activated under 808 nm laser irradiation to produce local hyperthermia and reactive oxygen species (ROS) for phototherapy. Moreover, PCPP NPs with extremely high Cy and Pt heavy metal contents in the backbone of the polyprodrug could directly track the nanodrugs themselves via near-infrared fluorescence (NIRF) imaging, photothermal imaging, and computed tomography (CT) imaging in vitro and in vivo. As revealed by trimodal imaging, PCPP NPs were found to exhibit excellent tumor accumulation and antitumor efficiency after intravenous injection into H22-tumor-bearing mice. The dual-drug backboned polyprodrug nanoplatform exhibited great potential for bioimaging and combined chemo-phototherapy.

NIR and Reduction Dual-Sensitive Polymeric Prodrug Nanoparticles for Bioimaging and Combined Chemo-Phototherapy

The combination of chemotherapy, photothermal therapy (PTT) and photodynamic therapy (PDT) based on a single nanosystem is highly desirable for cancer treatment. In this study, we developed a versatile Pt(IV) prodrug-based nanodrug, PVPt@Cy NPs, to realize synchronous chemotherapy, PDT and PTT and integrate cancer treatment with bioimaging. To construct PVPt@Cy NPs, the amphiphilic Pt(IV)-based polymeric prodrug PVPt was synthesized by a facile one-pot coupling reaction, and then it was used to encapsulate an optotheranostic agent (HOCyOH, Cy) via hydrophobic interaction-induced self-assembly. These NPs would disaggregate under acidic, reductive conditions and NIR irradiation, which are accompanied by photothermal conversion and reactive oxygen species (ROS) generation. Moreover, the PVPt@Cy NPs exhibited an enhanced in vitro anticancer efficiency with 808-nm light irradiation. Furthermore, the PVPt@Cy NPs showed strong NIR fluorescence and photothermal imaging in H22 tumor-bearing mice, allowing the detection of the tumor site and monitoring of the drug biodistribution. Therefore, PVPt@Cy NPs displayed an enormous potential in combined chemo-phototherapy.

Novel Prodrug Supramolecular Nanoparticles Capable of Rapid Mitochondrial-Targeted and ROS-Responsive for Pancreatic Cancer Therapy

Mitochondrial dysfunction is a feature of cancer cells and targeting cancer mitochondria has emerged as a promising anticancer therapy. In this study, a novel mitochondria-targeted and ROS-responsive drug delivery nanoplatform...

Multi-functional polymeric micelles for chemotherapy-based combined cancer therapy

Currently, the therapeutic performance of traditional mono-chemotherapy on cancers remains unsatisfactory because of the tumor heterogeneity and multidrug resistance. In light of intricate tumor structures and distinct tumor microenvironments (TMEs), combinational therapeutic strategies with multiple anticancer drugs from different mechanisms can synergistically optimize the outcomes and concomitantly minimize the adverse effects during the therapy process. Extensive research on polymeric micelles (PMs) for biomedical applications has revealed the growing importance of nanomedicines for cancer therapy in the recent decade. Starting from traditional simple delivery systems, PMs have been extended to multi-faceted therapeutic strategies. Here we review and summarize the most recent advances in combinational therapy based on multifunctional PMs including a combination of multiple anticancer drugs, chemo-gene therapy, chemo-phototherapy and chemo-immunotherapy. The design approaches, action mechanisms and therapeutic applications of these nanodrugs are summarized. In addition, we highlight the opportunities and potential challenges associated with this promising field, which will provide new guidelines for advanced combinational cancer chemotherapy.

Smart Design of Mitochondria-Targeted and ROS-Responsive CPI-613 Delivery Nanoplatform for Bioenergetic Pancreatic Cancer Therapy

Mitochondria, as the powerhouse of most cells, are not only responsible for the generation of adenosine triphosphate (ATP) but also play a decisive role in the regulation of apoptotic cell death, especially of cancer cells. Safe potential delivery systems which can achieve organelle-targeted therapy are urgently required. In this study, for effective pancreatic cancer therapy, a novel mitochondria-targeted and ROS-triggered drug delivery nanoplatform was developed from the TPP-TK-CPI-613 (TTCI) prodrug, in which the ROS-cleave thioketal functions as a linker connecting mitochondrial targeting ligand TPP and anti-mitochondrial metabolism agent CPI-613. DSPE-PEG2000 was added as an assistant component to increase accumulation in the tumor via the EPR effect. This new nanoplatform showed effective mitochondrial targeting, ROS-cleaving capability, and robust therapeutic performances. With active mitochondrial targeting, the formulated nanoparticles (TTCI NPs) demonstrate much higher accumulation in mitochondria, facilitating the targeted delivery of CPI-613 to its acting site. The results of in vitro antitumor activity and cell apoptosis revealed that the IC₅₀ values of TTCI NPs in three types of pancreatic cancer cells were around 20~30 µM, which was far lower than those of CPI-613 (200 µM); 50 µM TTCI NPs showed an increase in apoptosis of up to 97.3% in BxPC3 cells. Therefore, this mitochondria-targeted prodrug nanoparticle platform provides a potential strategy for developing safe, targeting and efficient drug delivery systems for pancreatic cancer therapy.

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.

IR780-based nanomaterials for cancer imaging and therapy

IR780, a small molecule with a strong optical property and excellent photoconversion efficiency following near infrared (NIR) irradiation, has attracted increasing attention in the field of cancer treatment and imaging. This review is focused on different IR780-based nanoplatforms and the application of IR780-based nanomaterials for cancer bioimaging and therapy. Thus, this review summarizes the overall aspects of IR780-based nanomaterials that positively impact cancer biomedical applications.

Recent Advances in pH- or/and Photo-Responsive Nanovehicles

The combination of nanotechnology and chemotherapy has resulted in more effective drug design via the development of nanomaterial-based drug delivery systems (DDSs) for tumor targeting. Stimulus-responsive DDSs in response to internal or external signals can offer precisely controlled delivery of preloaded therapeutics. Among the various DDSs, the photo-triggered system improves the efficacy and safety of treatment through spatiotemporal manipulation of light. Additionally, pH-induced delivery is one of the most widely studied strategies for targeting the acidic micro-environment of solid tumors. Accordingly, in this review, we discuss representative strategies for designing DDSs using light as an exogenous signal or pH as an endogenous trigger.

Self-assembled multifunctional polymeric micelles for tumor-specific bioimaging and synergistic chemo-phototherapy of cancer

Integration of multiple therapies into one nanoplatform holds great promise to overcome the shortcomings of traditional single-modal therapy and achieve favorable antitumor efficacy. Herein, we constructed a dual receptor-targeting nanomicelle system with GSH-responsive drug release for precise fluorescence imaging and superior chemo-phototherapy of cancer. The synthetic amphiphilic hyaluronic acid derivative (FHSV) could self-assemble into nanomicelles in aqueous media. Then, paclitaxel (PTX) and photosensitizer IR780 iodide (IR780) were co-loaded into the micelles by a simple dialysis method. The resulting IR780/PTX/FHSV micelles with a particle size of 150.2 ± 6.9 nm exhibited excellent stability, GSH-responsive drug release and good photothermal/photodynamic efficacy. Once accumulated at the tumor sites, IR780/PTX/FHSV micelles efficiently entered tumor cells through receptor-mediated endocytosis and then rapidly release PTX and IR780 under GSH-rich tumor microenvironment. Upon NIR laser irradiation, IR780 produced local hyperthermia and sufficient reactive oxygen species to promote tumor cells apoptosis and necrosis. The results of in vitro and in vivo experiments consistently demonstrated that compared with single chemotherapy and phototherapy, the chemo-phototherapy could more efficiently kill tumor cells by synergistic antitumor effect. Therefore, our study provides a novel and efficient approach for multimodal treatment of malignant tumor.

Phthalocyanine-Conjugated Glyconanoparticles for Chemo-photodynamic Combination Therapy

Combination cancer therapy based on multifunctional nanomaterials has attracted great attention. The present work focuses on the preparation of the glycopolymeric nanoparticle, which contains a photosensitizer (zinc(II)phthalocyanine, ZnPc) and an anticancer drug (Doxorubicin, Dox). First, a novel mono azide-functional ZnPc-N₃ with seven hydrophilic ethylene oxide chains was synthesized. Next, ZnPc alone or together with Dox bearing glycopolymers was synthesized via the RAFT polymerization method and then self-assembled into glyconanoparticles (GNPs) with narrow particle size distribution. Then the evaluation of the biological activity of GNPs (GNPs-ZnPc and GNPs-ZnPc/Dox) for dual photodynamic therapy (PDT) and chemotherapy against human breast cancer cells was investigated. The constructed GNPs were identified via general characterization methods, including dynamic light scattering (DLS) and transmission electron microscopy (TEM). The prepared GNPs-ZnPc/Dox demonstrated remarkable photophysical and photochemical properties, involving good colloidal stability in biological conditions, pH-responsive drug release, and the capacity to generate singlet oxygen under light irradiation. The outer layer of nanoparticles covered by fructose sugar moieties achieves a targeted cancer therapy owing to GLUT5 (a well-known fructose transporter) overexpression toward breast cancer cells. In vitro experiments were then performed to evaluate the chemo/phototoxicity, cellular uptake, and anticancer efficacy of GNPs-ZnPc/Dox. In comparison with free Dox, human breast cancer cells treated with GNPs-ZnPc/Dox exhibited a higher cellular internalization via GLUT5 targeting. In particular, the GNPs-ZnPc/Dox nanoplatform revealed an excellent synergistic anticancer activity in comparison with free ZnPc-N₃ and free Dox, representing a novel and promising chemo-photodynamic combination therapeutic methodology to improve therapeutic efficacy.

A review of advanced nanoformulations in phototherapy for cancer therapeutics

Phototherapy has the potential to play a greater role in oncology. Phototherapy converts light energy into either chemical energy or thermal energy, which eventually destroys cancer cells after a series of biological reactions. With nanotechnology applications in cancer therapeutics, it has become possible to prepare smart drug carriers with multifunctional properties at the nanoscale level. These nanocarriers may be able to deliver the drug molecules to the target site more efficiently in the form of nanoparticles. Several intrinsic and extrinsic properties of these nanocarriers help target the tumor cells exclusively, and by utilizing these features, drug molecules can be delivered to the tumor cells specifically, which results in high tumor uptake and better therapeutic effects ultimately. Nanocarriers can also be designed to carry different drugs together to provide a platform for combination therapy like chemo-photodynamic therapy and chemo-photodynamic-photothermal therapy. In combination therapy, co-delivery of all different drugs is crucial to obtain their synergistic effects, and with the help of nanocarriers, it is possible to co-deliver these drugs by loading them together onto the nanocarriers.

Visible-to-NIR-Light Activated Release: From Small Molecules to Nanomaterials

Photoactivatable (alternatively, photoremovable, photoreleasable, or photocleavable) protecting groups (PPGs), also known as caged or photocaged compounds, are used to enable non-invasive spatiotemporal photochemical control over the release of species of interest. Recent years have seen the development of PPGs activatable by biologically and chemically benign visible and near-infrared (NIR) light. These long-wavelength-absorbing moieties expand the applicability of this powerful method and its accessibility to non-specialist users. This review comprehensively covers organic and transition metal-containing photoactivatable compounds (complexes) that absorb in the visible- and NIR-range to release various leaving groups and gasotransmitters (carbon monoxide, nitric oxide, and hydrogen sulfide). The text also covers visible- and NIR-light-induced photosensitized release using molecular sensitizers, quantum dots, and upconversion and second-harmonic nanoparticles, as well as release via photodynamic (photooxygenation by singlet oxygen) and photothermal effects. Release from photoactivatable polymers, micelles, vesicles, and photoswitches, along with the related emerging field of photopharmacology, is discussed at the end of the review.

Photo-Enhanced CRISPR/Cas9 System Enables Robust PD-L1 Gene Disruption in Cancer Cells and Cancer Stem-Like Cells for Efficient Cancer Immunotherapy

Blocking immune checkpoint pathways with an antibody or small interfering RNA (siRNA) has become a promising method to reactivate antitumor responses for cancer treatment. However, both blockade strategies achieve only temporary inhibition of these immune checkpoints. Herein, a photoswitched CRISPR/Cas9 system for genomic disruption of the PD-L1 gene is developed to achieve permanent blockade of the PD-1/PD-L1 pathway; this system is constructed by using a photoactivated self-degradable polyethyleneimine derivative and the plasmid pX330/sgPD-L1 (expression of the Cas9 protein and single-guide RNA targeting PD-L1). Under light irradiation, this photoswitched CRISPR/Cas9 system efficiently genetically disrupts the PD-L1 gene in not only bulk cancer cells but also cancer stem-like cells. As a result, the photoswitched CRISPR/Cas9 system significantly increases the infiltration of CD8+ T cells into tumor tissue, leading to effective activation of a T cell-mediated antitumor response against cancer cells and cancer stem-like cells. This study provides an alternative strategy to block the PD-1/PD-L1 pathway for efficacious immune checkpoint therapy.

Assessing the Combinatorial Chemo-Photothermal Therapy Mediated by Sulfobetaine Methacrylate-Functionalized Nanoparticles in 2D and 3D In Vitro Cancer Models

Combinatorial cancer therapies mediated by nanomaterials can potentially overcome the limitations of conventional treatments. These therapies are generally investigated using 2D in vitro cancer models, leading to an inaccurate screening. Recently, 3D in vitro spheroids have emerged in the preclinical testing stage of nanomedicines due to their ability to mimic key features of the in vivo solid tumors. Investigate the chemo-photothermal therapy mediated by Doxorubicin and IR780 loaded sulfobetaine methacrylate functionalized nanoparticles, for the first time, using monolayers of cancer cells and spheroids. In the 2D cancer models, the nanomaterials' mediated photothermal therapy, chemotherapy, and chemo-photothermal therapy reduced cancer cells' viability to about 58%, 29%, and 1%, respectively. Interestingly, when the nanomaterials' mediated photothermal therapy is tested on 3D spheroids, no cytotoxic effect is noticed. In contrast, the nanostructures' induced chemotherapy decreased spheroids' viability to 42%. On the other hand, nanomaterials' mediated chemo-photothermal therapy diminished spheroids' viability to 16%, being the most promising therapeutic modality. These results demonstrate the importance of using 3D spheroids during the in vitro screening of single/combinatorial therapies mediated by nanomaterials.

A pH reversibly activatable NIR photothermal/photodynamic-in-one agent integrated with renewable nanoimplants for image-guided precision phototherapy

Phototherapy has great potential to revolutionize conventional therapeutic modalities. However, most phototherapeutic strategies based on multicomponent therapeutic agents generally lack tumor-specificity, resulting in asynchronous therapy and superimposed side-effects. Severe heat damage is also inevitable because of the necessity of continuous external irradiation. Here we show the design of an acid-activated and continuous external irradiation-free photothermal and photodynamic (PTT/PDT) synchronous theranostic nanoplatform for precision tumor-targeting near-infrared (NIR) image-guided therapy. pH-reversibly responsive brominated asymmetric cyanine is designed as the tumor-specific NIR PTT/PDT-in-one agent to enhance anticancer efficiency and reduce side-effects. Ultra-small NIR persistent luminescence nanoparticles are prepared as both the imaging unit and renewable nanoimplant. Biotin functionalized polyethylene glycol is introduced to endow active tumor-targeting ability and prolong blood-circulation. The developed smart platform offers merits of reversible activation, PTT/PDT synergetic enhancement, tumor targetability and continuous external irradiation-free properties, allowing autofluorescence-free image-guided phototherapy only in tumor sites. This work paves the way to developing smart theranostic nanoplatforms for precision medicine.

Stimulus-Responsive Nanomedicines for Disease Diagnosis and Treatment

Stimulus-responsive drug delivery systems generally aim to release the active pharmaceutical ingredient (API) in response to specific conditions and have recently been explored for disease treatments. These approaches can also be extended to molecular imaging to report on disease diagnosis and management. The stimuli used for activation are based on differences between the environment of the diseased or targeted sites, and normal tissues. Endogenous stimuli include pH, redox reactions, enzymatic activity, temperature and others. Exogenous site-specific stimuli include the use of magnetic fields, light, ultrasound and others. These endogenous or exogenous stimuli lead to structural changes or cleavage of the cargo carrier, leading to release of the API. A wide variety of stimulus-responsive systems have been developed-responsive to both a single stimulus or multiple stimuli-and represent a theranostic tool for disease treatment. In this review, stimuli commonly used in the development of theranostic nanoplatforms are enumerated. An emphasis on chemical structure and property relationships is provided, aiming to focus on insights for the design of stimulus-responsive delivery systems. Several examples of theranostic applications of these stimulus-responsive nanomedicines are discussed.