An efficient dual-loaded multifunctional nanocarrier for combined photothermal and photodynamic therapy based on copper sulfide and chlorin e6

Macromolecular Nano-Assemblies for Enhancing the Effect of Oxygen-Dependent Photodynamic Therapy Against Hypoxic Tumors

In oxygen (O2)-dependent photodynamic therapy (PDT), photosensitizers absorb light energy, which is then transferred to ambient O2 and subsequently generates cytotoxic singlet oxygen (1O2). Therefore, the availability of O2 and the utilization efficiency of generated 1O2 are two significant factors that influence the effectiveness of PDT. However, tumor microenvironments (TMEs) characterized by hypoxia and limited utilization efficiency of 1O2 resulting from its short half-life and short diffusion distance significantly restrict the applicability of PDT for hypoxic tumors. To address these challenges, numerous macromolecular nano-assemblies (MNAs) have been designed to relieve hypoxia, utilize hypoxia or enhance the utilization efficiency of 1O2. Herein, we provide a comprehensive review on recent advancements achieved with MNAs in enhancing the effectiveness of O2-dependent PDT against hypoxic tumors.

Advances in liposomes loaded with photoresponse materials for cancer therapy

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

Advances in Ferroptosis-Inducing Agents by Targeted Delivery System in Cancer Therapy

Currently, cancer remains one of the most significant threats to human health. Treatment of most cancers remains challenging, despite the implementation of diverse therapies in clinical practice. In recent years, research on the mechanism of ferroptosis has presented novel perspectives for cancer treatment. Ferroptosis is a regulated cell death process caused by lipid peroxidation of membrane unsaturated fatty acids catalyzed by iron ions. The rapid development of bio-nanotechnology has generated considerable interest in exploiting iron-induced cell death as a new therapeutic target against cancer. This article provides a comprehensive overview of recent advancements at the intersection of iron-induced cell death and bionanotechnology. In this respect, the mechanism of iron-induced cell death and its relation to cancer are summarized. Furthermore, the feasibility of a nano-drug delivery system based on iron-induced cell death for cancer treatment is introduced and analyzed. Secondly, strategies for inducing iron-induced cell death using nanodrug delivery technology are discussed, including promoting Fenton reactions, inhibiting glutathione peroxidase 4, reducing low glutathione levels, and inhibiting system Xc-. Additionally, the article explores the potential of combined treatment strategies involving iron-induced cell death and bionanotechnology. Finally, the application prospects and challenges of iron-induced nanoagents for cancer treatment are discussed.

Choline phosphate lipid-hitchhiked near-infrared BODIPY nanoparticles for enhanced phototheranostics

Phototheranostics integrating optical imaging and phototherapy has attracted extensive attention. Achieving nanophototherapeutics with near infrared (NIR)-light synchronously triggered photodynamic therapy (PDT) and photothermal therapy (PTT) is challenging. Herein, we develop a multifunctional theranostic nanoplatform prepared from the co-assembly of NIR boron dipyrromethene (BODIPY) with a cooperative D-π-A structure of a thiophene-BODIPY core and benzene-diethylamino, and a choline phosphate lipid. The as-fabricated nanoparticles (DBNPs) exhibited desirable NIR absorption, uniform spherical morphology and good colloidal stability. The elaborate molecular design and supramolecular assembly endowed DBNPs with desirable PDT and PTT activities. Upon 808 nm laser irradiation, the DBNPs efficiently generated active singlet oxygen and regional hyperpyrexia, with a photothermal conversion efficiency of 37.6%. The excellent PDT and PTT performance of DBNPs boosted the potent in vitro and in vivo anti-tumor effects. In addition, these nanoparticles manifested their good capability of NIR fluorescence imaging of tumors. Overall, the DBNPs provide a paradigm for delivering hydrophobic phototherapy molecules with phospholipids for enhanced tumor treatment and imaging.

BSA-coated β-FeOOH nanoparticles efficiently deliver the photosensitizer chlorin e6 for synergistic anticancer PDT/CDT

Photodynamic therapy (PDT) has many exceptional advantages in cancer treatment, such as minor trauma, low toxicity side effects, and strong adaptability, effectively overcoming some obstacles of traditional therapy and providing more revolutionary opportunities for curing cancer. Chlorin e6 (Ce6) exhibits excellent singlet oxygen generation and conversion efficiency under near-infrared laser irradiation and is a promising PDT photosensitizer. However, its hydrophobicity, short half-life and lack of tumor specificity limit its in vivo anticancer application. Therefore, this work has designed and prepared a multifunctional nanoplatform, Ce6/FeOOH@BSA, to efficiently deliver Ce6. Nanoparticles exhibit excellent dispersion and stability in deionized water, PBS and DMEM, and the blood half-life is 3.98 ± 0.31 h. The nanoplatform demonstrates effective tumor targeting and accumulation, overcoming the obstacles of the biological application of Ce6. Iron ions can exert a chemodynamic therapy (CDT) effect by reacting with overexpressed H₂O₂ in the tumor to generate toxic hydroxyl radicals (·OH). Moreover, FeOOH nanoparticles effectively promote glutathione (GSH) consumption in tumor cells, which is conducive to accumulating reactive oxygen species (ROS). In brief, Ce6/FeOOH@BSA nanoparticles realize the targeted delivery of Ce6 and mediate synergistic PDT/CDT against tumors, broadening the biomedical application of nanomaterials.

Multifunctional Photoactive Nanomaterials for Photodynamic Therapy against Tumor: Recent Advancements and Perspectives

Numerous treatments are available for cancer, including chemotherapy, immunotherapy, radiation therapy, hormone therapy, biomarker testing, surgery, photodynamic therapy, etc. Photodynamic therapy (PDT) is an effective, non-invasive, novel, and clinically approved strategy to treat cancer. In PDT, three main agents are utilized, i.e., photosensitizer (PS) drug, oxygen, and light. At first, the photosensitizer is injected into blood circulation or applied topically, where it quickly becomes absorbed or accumulated at the tumor site passively or actively. Afterward, the tumor is irradiated with light which leads to the activation of the photosensitizing molecule. PS produces the reactive oxygen species (ROS), resulting in the death of the tumor cell. However, the effectiveness of PDT for tumor destruction is mainly dependent on the cellular uptake and water solubility of photosensitizer molecules. Therefore, the delivery of photosensitizer molecules to the tumor cell is essential in PDT against cancer. The non-specific distribution of photosensitizer results in unwanted side effects and unsuccessful therapeutic outcomes. Therefore, to improve PDT clinical outcomes, the current research is mostly focused on developing actively targeted photosensitizer molecules, which provide a high cellular uptake and high absorption capacity to the tumor site by overcoming the problem associated with conventional PDT. Therefore, this review aims to provide current knowledge on various types of actively and passively targeted organic and inorganic nanocarriers for different cancers.

A Smart Nanoreactor Based on an O2-Economized Dual Energy Inhibition Strategy Armed with Dual Multi-stimuli-Responsive "Doorkeepers" for Enhanced CDT/PTT of Rheumatoid Arthritis

Activated fibroblast-like synovial (FLS) cells are regarded as an important target for rheumatoid arthritis (RA) treatment via starvation therapy mediated by glucose oxidase (GOx). However, the hypoxic RA-FLS environment greatly reduces the oxidation process of glucose and leads to a poor therapeutic effect of the GOx-based starvation therapy. In this work, we designed a hollow mesoporous copper sulfide nanoparticles (CuS NPs)-based smart GOx/atovaquone (ATO) codelivery system (named as V-HAGC) targeting RA-FLS cells to realize a O₂-economized dual energy inhibition strategy to solve the limitation of GOx-based starvation therapy. V-HAGC armed with dual multi-stimuli-responsive "doorkeepers" can guard drugs intelligently. Once under the stimulation of photothermal and acidic conditions at the targeted area, the dual intelligent responsive "doors" would orderly open to realize the controllable release of drugs. Besides, the efficacy of V-HAGC would be much improved by the additional chemodynamic therapy (CDT) and photothermal therapy (PTT) stimulated by CuS NPs. Meanwhile, the upregulated H₂O₂ and acid levels by starvation therapy would promote the Fenton-like reaction of CuS NPs under O₂-economized dual energy inhibition, which could enhance the PTT and CDT efficacy as well. In vitro and in vivo evaluations revealed V-HAGC with much improved efficacy of this combination therapy for RA. In general, the smart V-HAGC based on the O₂-economized dual energy inhibition strategy combined with enhanced CDT and PTT has the potential to be an alternative methodology in the treatment of RA.

Reasonable design of NIR AIEgens for fluorescence imaging and effective photothermal/photodynamic cancer therapy

The development of a multifunctional single molecule phototherapeutic agent with excellent fluorescence imaging, photothermal therapy and photodynamic therapy at the same time is still a challenging task, which mainly arises from the low absorbance of the molecule, and the complexity of energy dissipation and molecular design. Herein, four donor-acceptor (D-A) compounds were synthesized by linking triphenylamine (TPA), thiophene/thieno[3,2-b]thiophene and different cyano acceptor structures. In this design, we propose a molecular design strategy to redshift absorption and increase the molar extinction coefficient (ε) by enhancing electron-withdrawing acceptors and enlarging the π-conjugation plane unit. Due to the twisted structure of TPA, these compounds exhibit aggregation-induced emission (AIE) characteristics. Notably, these AIEgens have long emission wavelengths, excellent photostability, biocompatibility, photothermal stability and singlet oxygen (¹O₂) generation performance. Among them, the photothermal conversion efficiency of a compound (named TCF-SS-TPA NPs) can reach 84.5%. Cellular internalization and therapy showed that TCF-SS-TPA NPs have good biocompatibility, excellent cell bioimaging and cancer phototherapy capabilities in vitro. This study will stimulate the molecular design of multifunctional phototherapeutics to realize effective synergistic cancer therapy.

Multi-Functional Liposome: A Powerful Theranostic Nano-Platform Enhancing Photodynamic Therapy

Although photodynamic therapy (PDT) has promising advantages in almost non-invasion, low drug resistance, and low dark toxicity, it still suffers from limitations in the lipophilic nature of most photosensitizers (PSs), short half-life of PS in plasma, poor tissue penetration, and low tumor specificity. To overcome these limitations and enhance PDT, liposomes, as excellent multi-functional nano-carriers for drug delivery, have been extensively studied in multi-functional theranostics, including liposomal PS, targeted drug delivery, controllable drug release, image-guided therapy, and combined therapy. This review provides researchers with a useful reference in liposome-based drug delivery.

Protein-drug conjugate programmed by pH-reversible linker for tumor hypoxia relief and enhanced cancer combination therapy

Combining functional proteins with small molecular drugs into one entity may endow distinct synergistic advantages. However, on account of completely different physicochemical properties of such payloads, co-delivery through systemic administration for therapeutic purpose is challenging. Herein, we designed the protein-drug conjugate HSAP-DC-CAT (human serum albumin/Pt (IV)-dibenzocyclooctyne/chlorin e6-catalase) by modification of CAT and cisplatin pro-drug loaded HSA with pH-sensitive azide linker 3-(azidomethyl)-4-methyl-2,5-furandione (AzMMMan) followed by click chemistry assembly with DC. The dynamic covalent bonds between linker and proteins, on the one hand, can bridge proteins and small molecular drugs in the intermediate state for systemic delivery in the harsh in vivo environment; on the other hand, it can trigger traceless cleavage and release of drugs and proteins with full bioactivity in acidic microenvironment of tumor. The multifunctional HSAP-DC-CAT provides efficient cytosolic transduction in vitro, excellent blood half-lives after systemic administration, and significant antitumor outcome via integrated cisplatin-based chemotherapy and Ce6-based photodynamic therapy enhanced by catalase-induced manipulation of tumor hypoxia microenvironment. This study describes a universal formulation strategy for protein and small molecular drug by a bifunctional linker through amide reaction and click chemistry, with traceless in vivo release of therapeutic units.

Rational design of oxygen deficient TiO2-x nanoparticles conjugated with chlorin e6 (Ce6) for photoacoustic imaging-guided photothermal/photodynamic dual therapy of cancer

Oxygen deficient TiO2-x nanoparticles (NPs) have been recognized as a category of new-fashioned photothermal agents to offer safer PTT. However, the surface of TiO2-x NPs is deficient in free active groups or radicals to conjugate functional therapeutic molecules, which seriously impedes their in-depth development for versatile medical applications. In this study, surface activation of TiO2-x NPs was realized by the facile conjugation of (3-aminopropyl)triethoxysilane (APTES) through the formation of a stable Si-O-Ti bond, and photosensitizer chlorin e6 (Ce6) was successfully modified onto the TiO2-x NP surface and with a considerably high loading content. The resultant TiO2-x@APTES/Ce6 (TAC) NPs displayed decent biosafety, rapid tumor enrichment and outstanding performance in photoacoustic (PA) imaging. Taking advantage of the intense photo-absorption in the near-infrared (NIR) region and high dose of conjugated Ce6, a powerful antitumor effect was realized based on the combination of hyperthermia-induced cell ablation and cytotoxic reactive oxygen species (ROS)-triggered apoptosis both in vitro and in vivo. Moreover, PA imaging guidance was exceptionally useful for locating the tumor position and optimizing the treatment regimens. Apart from Ce6, this elaborate modification strategy for TiO2-x is believed to be universal for steadily binding more versatile therapeutic agents, which would definitely favor the development of multifunctional TiO2-x-based nanocomplexes for enhanced tumor treatment.

Albumin-functionalized CuFeS2/photosensitizer nanohybrid for single-laser-induced folate receptor-targeted photothermal and photodynamic therapy

Multimodal therapy is an emerging medical intervention to overcome the current limitation in cancer therapy combining treatment modalities with different mechanisms of action to eradicate tumors. This study demonstrates a targeted multifunctional bovine serum albumin (BSA)-functionalized CuFeS₂/chlorin e6 (Ce6) for synergistic photothermal therapy (PTT) and photodynamic therapy (PDT) effects. The CuFeS₂ nanocrystals were synthesized through a simple heating-up approach and transferred into an aqueous phase using BSA in an ultrasonic-assisted microemulsion method. The as-prepared CuFeS₂@BSA nanoparticles further conjugated with folic acid (FA) followed by attachment of Ce6 to form the Ce6:CuFeS₂@BSA-FA nanohybrid with improved solubility and strong near-infrared (NIR) absorbance and fluorescence. It is the first report to fabricate the targeted Ce6:CuFeS₂@BSA-FA hybrid and evaluates their synergistic PTT/PDT effect using a single laser. The Ce6:CuFeS₂@BSA-FA hybrid showed lower toxicity in vitro (HeLa and HepG2 cells) and in vivo (zebrafish embryos), while they are selectively recognized and internalized by HeLa cells that over-express folate receptors. Compared to each modality applied separately, the combined single-laser-induced PTT and PDT treatment showed the enhanced generation of heat and reactive oxygen species (ROS) with synergistic cancer killing under 671 nm laser irradiation (10 min, 1 W/cm²). As a biocompatible targeted nanoprobe, the multifunctional nanohybrid holds promise in combined PDT/PTT synergistic therapy to achieve better efficacy.

Copper sulfide: An emerging adaptable nanoplatform in cancer theranostics

Copper sulfide nanoparticles (CuS NPs), emerging nanoplatforms with dual diagnostic and therapeutic applications, are being actively investigated in this era of "war on cancer" owing to their versatility and adaptability. This article discusses the pros and cons of using CuS NPs in diagnostics, therapeutics, and theranostics. The first section introduces CuS NPs and discusses the features that render them more advantageous than other established nanoplatforms in cancer management. Subsequent sections include specific in vitro and in vivo results of different studies showing the potential of CuS NPs as nanoplatforms. Methods used for visualization (photoacoustic imaging and magnetic resonance imaging) of CuS NPs and treatment (phototherapy and combinatorial therapy) have also been discussed. Furthermore, the challenges and opportunities associated with using CuS NPs have been elucidated. Further investigations on CuS NPs are required to translate it for clinical applications.

Biomorphic Engineering of Multifunctional Polylactide Stomatocytes toward Therapeutic Nano-Red Blood Cells

Morphologically discrete nanoarchitectures, which mimic the structural complexity of biological systems, are an increasingly popular design paradigm in the development of new nanomedical technologies. Herein, engineered polymeric stomatocytes are presented as a structural and functional mimic of red blood cells (RBCs) with multifunctional therapeutic features. Stomatocytes, comprising biodegradable poly(ethylene glycol)-block-poly(D,L-lactide), possess an oblate-like morphology reminiscent of RBCs. This unique dual-compartmentalized structure is augmented via encapsulation of multifunctional cargo (oxygen-binding hemoglobin and the photosensitizer chlorin e6). Furthermore, stomatocytes are decorated with a cell membrane isolated from erythrocytes to ensure that the surface characteristics matched those of RBCs. In vivo biodistribution data reveal that both the uncoated and coated nano-RBCs have long circulation times in mice, with the membrane-coated ones outperforming the uncoated stomatoctyes. The capacity of nano-RBCs to transport oxygen and create oxygen radicals upon exposure to light is effectively explored toward photodynamic therapy, using 2D and 3D tumor models; addressing the challenge presented by cancer-induced hypoxia. The morphological and functional control demonstrated by this synthetic nanosystem, coupled with indications of therapeutic efficacy, constitutes a highly promising platform for future clinical application.

Utilisation of Targeted Nanoparticle Photosensitiser Drug Delivery Systems for the Enhancement of Photodynamic Therapy

The cancer incidence world-wide has caused an increase in the demand for effective forms of treatment. One unconventional form of treatment for cancer is photodynamic therapy (PDT). PDT has 3 fundamental factors, namely a photosensitiser (PS) drug, light and oxygen. When a PS drug is administered to a patient, it can either passively or actively accumulate within a tumour site and once exposed to a specific wavelength of light, it is excited to produce reactive oxygen species (ROS), resulting in tumour destruction. However, the efficacy of ROS generation for tumour damage is highly dependent on the uptake of the PS in tumour cells. Thus, PS selective/targeted uptake and delivery in tumour cells is a crucial factor in PDT cancer drug absorption studies. Generally, within non-targeted drug delivery mechanisms, only minor amounts of PS are able to passively accumulate in tumour sites (due to the enhanced permeability and retention (EPR) effect) and the remainder distributes into healthy tissues, causing unwanted side effects and poor treatment prognosis. Thus, to improve the efficacy of PDT cancer treatment, research is currently focused on the development of specific receptor-based PS-nanocarrier platform drugs, which promote the active uptake and absorption of PS drugs in tumour sites only, avoiding unwanted side effects, as well as treatment enhancement. Therefore, the aim of this review paper is to focus on current actively targeted or passively delivered PS nanoparticle drug delivery systems, that have been previously investigated for the PDT treatment of cancer and so to deduce their overall efficacy and recent advancements.

Evaluating Nanoshells and a Potent Biladiene Photosensitizer for Dual Photothermal and Photodynamic Therapy of Triple Negative Breast Cancer Cells

Light-activated therapies are ideal for treating cancer because they are non-invasive and highly specific to the area of light application. Photothermal therapy (PTT) and photodynamic therapy (PDT) are two types of light-activated therapies that show great promise for treating solid tumors. In PTT, nanoparticles embedded within tumors emit heat in response to laser light that induces cancer cell death. In PDT, photosensitizers introduced to the diseased tissue transfer the absorbed light energy to nearby ground state molecular oxygen to produce singlet oxygen, which is a potent reactive oxygen species (ROS) that is toxic to cancer cells. Although PTT and PDT have been extensively evaluated as independent therapeutic strategies, they each face limitations that hinder their overall success. To overcome these limitations, we evaluated a dual PTT/PDT strategy for treatment of triple negative breast cancer (TNBC) cells mediated by a powerful combination of silica core/gold shell nanoshells (NSs) and palladium 10,10-dimethyl-5,15-bis(pentafluorophenyl)biladiene-based (Pd[DMBil1]-PEG₇₅₀) photosensitizers (PSs), which enable PTT and PDT, respectively. We found that dual therapy works synergistically to induce more cell death than either therapy alone. Further, we determined that low doses of light can be applied in this approach to primarily induce apoptotic cell death, which is vastly preferred over necrotic cell death. Together, our results show that dual PTT/PDT using silica core/gold shell NSs and Pd[DMBil1]-PEG₇₅₀ PSs is a comprehensive therapeutic strategy to non-invasively induce apoptotic cancer cell death.

A New Treatment Modality for Rheumatoid Arthritis: Combined Photothermal and Photodynamic Therapy Using Cu7.2 S4 Nanoparticles

Rheumatoid arthritis (RA) is a worldwide inflammatory disease that seriously threatens human health and needs more effective treatment approaches. Near infrared (NIR) light can efficiently penetrate inflamed joints affected by RA, so phototherapy, including photothermal therapy (PTT) and photodynamic therapy (PDT), may provide new opportunities. In this work, the unique Cu_7.2 S₄ nanoparticles (NPs) are prepared for RA treatment enlightened by the fact that copper (Cu)-based nanomaterials can simultaneously serve as PTT agents and photosensitizers (for PDT). Meanwhile, Cu can promote ostogenesis and chondrogenesis. The Cu_7.2 S₄ NPs combined with NIR (808 nm, 1 W cm^-2 ) irradiation not only achieve better bone preservation, including higher bone mineral density (BMD) and bone volume/total volume, but also inhibit inflamed synovial invasion, cartilage erosion, and expression of proinflammatory cytokines in vivo. Moreover, the Cu_7.2 S₄ NPs can effectively kill clinical pathogenic Staphylococcus aureus and Escherichia coli to prevent bacterial infection during intra-articular injection. Therefore, the combined PTT and PDT using the multifunctional Cu_7.2 S₄ NPs could be a novel RA treatment modality with full potential.

Color-tunable AIE-active conjugated polymer nanoparticles as drug carriers for self-indicating cancer therapy via intramolecular FRET mechanism

In this paper, two novel AIE-active conjugated polymers were synthesized by Pd-catalyzed Suzuki coupling polymerization reaction.

Photosensitizer in lipid nanoparticle: a nano-scaled approach to antibacterial function

Photosensitization-based antimicrobial therapy (PAT) is an alternative therapy aimed at achieving bacterial inactivation. Researchers use various photosensitizers to achieve bacterial inactivation. However, the most widely used approach involves the use of photosensitizers dispersed in aqueous solution, which could limit the effectiveness of photodynamic inactivation. Therefore, the approaches to encapsulate the photosensitizer in appropriate vehicles can enhance the delivery of the photosensitizer. Herein, Toluidine Blue O (TBO) was the photosensitizer, and lipid nanoparticles were used for its encapsulation. The lipid nanoparticle-based delivery system has been tailor-made for decreasing the average size and viscosity and increasing the formulation stability as well as the wettability of skin. Usage of an appropriate vehicle will also increase the cellular uptake of the photosensitizer into the bacterial cells, leading to the damage on cell membrane and genomic DNA. Evidence of effectiveness of the developed PAT on planktonic bacteria and biofilms was examined by fluorescence microscopy and scanning electron microscopy. Lipid nanoparticles protected the photosensitizer from aggregation and made the application easy on the skin as indicated in data of size distribution and contact angle. The use of lipid nanoparticles for encapsulating TBO could enhance photosensitization-based antimicrobial therapy as compared to the aqueous media for delivering photosensitizers.

Hollow Au-Cu Nanocomposite for Real-Time Tracing Photothermal/Antiangiogenic Therapy

High absorption in the near-infrared (NIR) region is essential for a photoabsorbing agents to realize efficient photothermal therapy (PTT) for cancer. Here, a novel hollow Au-Cu nanocomposite (HGCNs) is developed, which displays a significantly enhanced NIR surface plasmon resonance absorption and photothermal transduction efficiency. Besides, fluorescent polymer dots poly(9,9-dioctylfluorene-2,7-diyl-co-benzothiadiazole) (PFBT) and chemotherapeutic mammalian target of rapamycin (mTOR) inhibitor agent rapamycin (RAPA) are attached onto the HGCNs (RAPA/PFBT-HGCNs) for real-time NIR fluorescence tracing and combined PTT/antiangiogenesis therapy. In particular, due to the fluorescence resonance energy transfer effect, RAPA/PFBT-HGCNs can act as NIR-activatable on/off probe system for real-time tracing of tumor tissues. A standard in vitro cellular uptake study, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, dual-staining study, and flow cytometry assay reveal that the RAPA/PFBT-HGCNs combined with NIR laser exhibit higher drug accumulation and cytotoxicity in both tumor cells and epithelial cells. Moreover, the margins of tumor and normal tissue can be accurately indicated by NIR-stimulated dequenched PFBT after 24 h intravenous administration. Further, tumor growth can be considerably hampered by the optimal formulation plus laser treatment with relatively lower side effects. Consequently, the work highlights the real-time tracing and enhanced PTT/antiangiogenesis therapy prospects of the established HGCNs with tremendous potential for treatment of cancer.

Controllable Photodynamic Therapy Implemented by Regulating Singlet Oxygen Efficiency

With singlet oxygen (1O2) as the active agent, photodynamic therapy (PDT) is a promising technique for the treatment of various tumors and cancers. But it is hampered by the poor selectivity of most traditional photosensitizers (PS). In this review, we present a summary of controllable PDT implemented by regulating singlet oxygen efficiency. Herein, various controllable PDT strategies based on different initiating conditions (such as pH, light, H2O2 and so on) have been summarized and introduced. More importantly, the action mechanisms of controllable PDT strategies, such as photoinduced electron transfer (PET), fluorescence resonance energy transfer (FRET), intramolecular charge transfer (ICT) and some physical/chemical means (e.g. captivity and release), are described as a key point in the article. This review provide a general overview of designing novel PS or strategies for effective and controllable PDT.

A generic 89Zr labeling method to quantify the in vivo pharmacokinetics of liposomal nanoparticles with positron emission tomography

Liposomal nanoparticles are versatile drug delivery vehicles that show great promise in cancer therapy. In an effort to quantitatively measure their in vivo pharmacokinetics, we developed a highly efficient 89Zr liposome-labeling method based on a rapid ligand exchange reaction between the membrane-permeable 89Zr(8-hydroxyquinolinate)4 complex and the hydrophilic liposomal cavity-encapsulated deferoxamine (DFO). This novel 89Zr-labeling strategy allowed us to prepare radiolabeled forms of a folic acid (FA)-decorated active targeting 89Zr-FA-DFO-liposome, a thermosensitive 89Zr-DFO-liposome, and a renal avid 89Zr-PEG-DFO-liposome at room temperature with near-quantitative isolated radiochemical yields of 98%±1% (n=6), 98%±2% (n=5), and 97%±1% (n=3), respectively. These 89Zr-labeled liposomal nanoparticles showed remarkable stability in phosphate-buffered saline and serum at 37°C without leakage of radioactivity for 48 h. The uptake of 89Zr-FA-DFO-liposome by the folate receptor-overexpressing KB cells was almost 15-fold higher than the 89Zr-DFO-liposome in vitro. Positron emission tomography imaging and ex vivo biodistribution studies enabled us to observe the heterogeneous distribution of the 89Zr-FA-DFO-liposome and 89Zr-DFO-liposome in the KB tumor xenografts, the extensive kidney accumulation of the 89Zr-FA-DFO-liposome and 89Zr-PEG-DFO-liposome, and the different metabolic fate of the free and liposome-encapsulated 89Zr-DFO. It also unveiled the poor resistance of all three liposomes against endothelial uptake resulting in their catabolism and high uptake of free 89Zr in the skeleton. Thus, this technically simple 89Zr-labeling method would find widespread use to guide the development and clinical applications of novel liposomal nanomedicines.

Design of Tumor Acidity-Responsive Sheddable Nanoparticles for Fluorescence/Magnetic Resonance Imaging-Guided Photodynamic Therapy

Imaging-guided cancer therapy, which integrates diagnostic and therapeutic functionalities into a single system, holds great promise to enhance the accuracy of diagnosis and improve the efficacy of therapy. Specifically, for photodynamic therapy (PDT), it is highly desirable to precisely focus laser light onto the tumor areas to generate reactive oxygen species (ROS) that are cytotoxic tumor cells and avoid light-associated side effects. Herein, a distinct three-layer nanostructured particle with tumor acidity-responsiveness (S-NP) that encapsulates the photosensitizer chlorin e6 (Ce6) and chelates Gd³⁺ is successfully developed for fluorescence/magnetic resonance (MR) dual-model imaging-guided precision PDT. We show clear evidence that the outer PEG layer significantly prolongs circulation time, and the inner poly(ε-caprolactone) (PCL) core can physically encapsulate Ce6. More interestingly, the middle layer of the S-NP, acting as a molecular fence to keep Ce6 in the circulation system, was dismantled by the slightly acidic tumor microenvironment. Afterwards, the PEG shell is deshielded from the S-NP at the tumor tissue, resulting in improved cell uptake, enlarged MR signal intensity, rapid release of Ce6 within tumor cells, and elevated PDT efficacy. Our results suggest that tumor-acidity-responsive nanoparticles with fine design could serve as a theranostic platform with great potential in imaging-guided PDT treatment of cancer.

Programmed near-infrared light-responsive drug delivery system for combined magnetic tumor-targeting magnetic resonance imaging and chemo-phototherapy

In this study, an intelligent drug delivery system was developed by capping doxorubicin (DOX)-loaded hollow mesoporous CuS nanoparticles (HMCuS NPs) with superparamagnetic iron oxide nanoparticles (IONPs). Under near infrared (NIR) light irradiation, the versatile HMCuS NPs could exploit the merits of both photothermal therapy (PTT) and photodynamic therapy (PDT) simultaneously. Herein, the multifunctional IONPs as gatekeeper with the enhanced capping efficiency were supposed to realize "zero premature release" and minimize the adverse side effects during the drug delivery in vivo. More importantly, the hybrid metal nanoplatform (HMCuS/DOX@IONP-PEG) allowed several emerging exceptional characteristics. Our studies have substantiated the hybrid nanoparticles possessed an enhanced PTT effect due to coupled plasmonic resonances with an elevated heat-generating capacity. Notably, an effective removal of IONP-caps occurred after NIR-induced photo-hyperthermia via weakening of the coordination interactions between HMCuS-NH₂ and IONPs, which suggested the feasibility of sophisticated controlled on-demand drug release upon exposing to NIR stimulus with spatial/temporal resolution. Benefiting from the favorable magnetic tumor targeting efficacy, the in vitro and in vivo experiments indicated a remarkable anti-tumor therapeutic efficacy under NIR irradiation, resulting from the synergistic combination of chemo-phototherapy. In addition, T₂-weighted magnetic resonance imaging (MRI) contrast performance of IONPs provided the identification of cancerous lesions. Based on these findings, the well-designed drug delivery system via integration of programmed functions will provide knowledge for advancing multimodality theranostic strategy.

STATEMENT OF SIGNIFICANCE

As we all know, a series of shortcomings of conventional chemotherapy such as limited stability, rapid clearing and non-specific tumor targeting ability remain a significant challenge to achieve successful clinical therapeutic efficiency in cancer treatments. Fortunately, developing drug delivery system under the assistance of multifunctional nanocarries might be a great idea. For the first time, we proposed an intelligent drug delivery system by capping DOX-loaded hollow mesoporous CuS nanoparticles (HMCuS NPs) with multifunctional IONPs to integrate programmed functions including enhanced PTT effect, sophisticated controlled drug release, magnetic targeting property and MR imaging. The results showed HMCuS/DOX@IONP-PEG could significantly enhance anti-tumor therapeutic efficacy due to the synergistic combination of chemo-phototherapy. By this delicate design, we believe such smart and extreme versatile all-in-one drug delivery platform could arouse broad interests in the fields of biomaterials, nanotechnology, and drug delivery system.

Functional hollow nanostructures for imaging and phototherapy of tumors

Various types of inorganic and organic phototherapeutic hollow nanostructures for the imaging and treatment of tumors are reviewed.

Indocyanine Green-Loaded Silver Nanoparticle@Polyaniline Core/Shell Theranostic Nanocomposites for Photoacoustic/Near-Infrared Fluorescence Imaging-Guided and Single-Light-Triggered Photothermal and Photodynamic Therapy

Photoacoustic (PA)/near-infrared fluorescence (NIRF) dual-modal imaging-guided phototherapy has been wide explored very recently. However, the development of high-efficiency and simplified-performed theranostic system for amplifying imaging-guided photothermal therapy/photodynamic therapy (PTT/PDT) is still a great challenge. Herein, a single-light-triggered indocyanine green (ICG)-loaded PEGylation silver nanoparticle core/polyaniline shell (Ag@PANI) nanocomposites (ICG-Ag@PANI) for PA/NIRF imaging-guided enhanced PTT/PDT synergistic effect has been successfully constructed. In this study, the synthesized Ag@PANI nanocomposites are utilized not only as the promising photothermal agent but also as potential nanovehicles for loading photosensitizer ICG via π-π stacking and hydrophobic interaction. The as-prepared ICG-Ag@PANI possesses many superior properties such as strong optical absorption in the near-infrared (NIR) region, enhanced photostability of ICG, as well as outstanding NIR laser-induced local hyperthermia and reactive oxygen species (ROS) generation. In the in vivo study, PA/NIRF dual-modal imaging confirms the accumulation and distribution of ICG-Ag@PANI in the tumor region via enhanced permeability and retention (EPR) effect. Moreover, the PTT effect of ICG-Ag@PANI rapidly raised the tumor temperature to 56.8 °C within 5 min. It is also demonstrated that the cytotoxic ROS generation ability of ICG is well maintained after being loaded onto Ag@PANI nanocomposites. Remarkably, in comparison with PTT or PDT alone, the single 808 nm NIR laser-triggered combined PTT/PDT therapy exhibits enhanced HeLa cells lethality in vitro and tumor growth inhibition in vivo.

Recent advances in the preparation and application of multifunctional iron oxide and liposome-based nanosystems for multimodal diagnosis and therapy

Nowadays, thanks to the successful discoveries in the biomedical field achieved in the last two decades, a deeper understanding about the complexity of mechanistic aspects of different pathological processes has been obtained. As a consequence, even the standard therapeutic protocols have undergone a vast redesign. In fact, the awareness about the necessity to progress towards a combined multitherapy in order to potentially increase the final healing chances has become a reality. One of the crucial elements of this novel approach is that large amounts of detailed information are highly needed and in vivo imaging techniques represent one of the most powerful tools to visualize and monitor the pathological state of the patient. To this scope, due to their unique features, nanostructured materials have emerged as attractive elements for the development of multifunctional tools for diagnosis and therapy. Hence, in this review, the most recent and relevant advances achieved by applying multifunctional nanostructures in multimodal theranosis of different diseases will be discussed. In more detail, the preparation and application of single multifunctional nano-radiotracers based on iron oxides and enabling PET/MRI dual imaging will be firstly detailed. After that, especially considering their highly promising clinical potential, the preparation and application of multifunctional liposomes useful for multimodal imaging and therapy will be reviewed. In both cases, a special focus will be set on the application of such a multifunctional nanocarriers in cancer as well as cardiovascular diseases.

CuS–Pt(iv)–PEG–FA nanoparticles for targeted photothermal and chemotherapy

CuS–Pt(iv) nanoparticles exhibited high in vitro and in vivo anti-tumor efficiency, which was caused by the integrated Pt drug-induced chemotherapy and CuS nanoparticle-mediated photothermal therapy (PTT) upon irradiation with near infrared (NIR) light.