Chemotherapeutic drug-photothermal agent co-self-assembling nanoparticles for near-infrared fluorescence and photoacoustic dual-modal imaging-guided chemo-photothermal synergistic therapy

In Vivo Quantitative Assessment of a Radiation Dose Based on Ratiometric Photoacoustic Imaging of Tumor Apoptosis

Accurately assessing the radiation level of tumors and surrounding tissues is of great significance for the optimization of clinical therapeutic interventions as well as minimizing the radiation-induced side effects. Therefore, the development of noninvasive and sensitive biological dosimeters is vital to achieve quantitative detection of a radiation dose in a living system. Herein, as a proof of concept, we report a tumor-targeted and caspase-3-activatable NIR fluorogenic probe AcDEVD-Cy-RGD consisting of a hemicyanine fluorophore as a signal reporter, a caspase-3 specific Asp-Glu-Val-Asp (DEVD) peptide, and a cyclic Arg-Gly-Asp peptide (cRGD) for tumor targeting. Upon cleavage with activated caspase-3, this probe not only displays the lighted-up NIR fluorescence, but also ratiometric photoacoustic (PA₇₁₀/PA₆₈₀) signals concurrently in a caspase-3 concentration-dependent manner, allowing for sensitive and quantitative detection of caspase-3 activity through both fluorescence and PA imaging, which provides the possibility for real-time monitoring of tumor cell apoptosis in a living system. More notably, we utilized this probe to successfully realize the direct visualization of tumor response to chemo- or radiotherapy and, for the first time, achieve the accurate estimation of radiation doses imparted to the tumors. We thus believe that our current strategy would offer an attractive and valuable means for the precise assessment of locally delivered radiation doses in various clinical settings.

Elaborately Engineering of a Dual-Drug Co-Assembled Nanomedicine for Boosting Immunogenic Cell Death and Enhancing Triple Negative Breast Cancer Treatment

Pure drug-assembled nanosystem provides a facile and promising solution for simple manufacturing of nanodrugs, whereas a lack of understanding of the underlying assembly mechanism and the inefficient and uncontrollable drug release still limits the development and application of this technology. Here, a simple and practical nanoassembly of DOX and DiR is constructed on basis of their co-assembly characteristics. Multiple interaction forces are found to drive the co-assembly process. Moreover, DOX release from the nanoassembly can be well controlled by the acidic tumor microenvironment and laser irradiation, resulting in favorable delivery efficiency of DiR and DOX in vitro and in vivo. As expected, the nanoassembly with high therapeutic safety completely eradicated the mice triple negative breast cancer cells (4T1) on BALB/c mice, owing to synergistic chemo-photothermal therapy. More interestingly, DiR and DOX synergistically induce immunogenic cell death (ICD) of tumor cells after treatment, enabling the mice to acquire immune memory against tumor growth and recurrence. Such a facile nanoassembly technique provides a novel multimodal cancer treatment platform of chemotherapy/phototherapy/immunotherapy.

Carrier-free nanodrugs with efficient drug delivery and release for cancer therapy: From intrinsic physicochemical properties to external modification

The considerable development of carrier-free nanodrugs has been achieved due to their high drug-loading capability, simple preparation method, and offering "all-in-one" functional platform features. However, the native defects of carrier-free nanodrugs limit their delivery and release behavior throughout the in vivo journey, which significantly compromise the therapeutic efficacy and hinder their further development in cancer treatment. In this review, we summarized and discussed the recent strategies to enhance drug delivery and release of carrier-free nanodrugs for improved cancer therapy, including optimizing the intrinsic physicochemical properties and external modification. Finally, the corresponding challenges that carrier-free nanodrugs faced are discussed and the future perspectives for its application are presented. We hope this review will provide constructive information for the rational design of more effective carrier-free nanodrugs to advance therapeutic treatment.

Exogenous Contrast Agents in Photoacoustic Imaging: An In Vivo Review for Tumor Imaging

The field of cancer theranostics has grown rapidly in the past decade and innovative 'biosmart' theranostic materials are being synthesized and studied to combat the fast growth of cancer metastases. While current state-of-the-art oncology imaging techniques have decreased mortality rates, patients still face a diminished quality of life due to treatment. Therefore, improved diagnostics are needed to define in vivo tumor growths on a molecular level to achieve image-guided therapies and tailored dosage needs. This review summarizes in vivo studies that utilize contrast agents within the field of photoacoustic imaging-a relatively new imaging modality-for tumor detection, with a special focus on imaging and transducer parameters. This paper also details the different types of contrast agents used in this novel diagnostic field, i.e., organic-based, metal/inorganic-based, and dye-based contrast agents. We conclude this review by discussing the challenges and future direction of photoacoustic imaging.

Binary dimeric prodrug nanoparticles for self-boosted drug release and synergistic chemo-photodynamic therapy

Chemotherapy is the major strategy for cancer therapy, but its limited therapeutic efficiency and serious toxicity to normal tissues greatly restrict its clinical performance. Herein, we develop carrier-free self-activated prodrug nanoparticles combining chemotherapy and photodynamic therapy to enhance the antitumor efficiency. Reactive oxygen species (ROS)-responsive paclitaxel and porphyrin prodrugs are synthesized and co-assembled into nanoparticles without the addition of any adjuvants, which improves the drug content and reduces carrier-associated toxicity. After entering cancer cells, the obtained co-assembled nanoparticles can generate sufficient ROS upon light irradiation not only for photodynamic therapy, but also triggering on-demand drug release for chemotherapy, thus realizing self-enhanced prodrug activation and synergistic chemo-photodynamic therapy. This simple and effective carrier-free prodrug nanoplatform unifies the distinct traits of on-demand drug release and combination therapy, thus possessing great potential in advancing cancer treatment.

Pure drug nano-assemblies: A facile carrier-free nanoplatform for efficient cancer therapy

Nanoparticulate drug delivery systems (Nano-DDSs) have emerged as possible solution to the obstacles of anticancer drug delivery. However, the clinical outcomes and translation are restricted by several drawbacks, such as low drug loading, premature drug leakage and carrier-related toxicity. Recently, pure drug nano-assemblies (PDNAs), fabricated by the self-assembly or co-assembly of pure drug molecules, have attracted considerable attention. Their facile and reproducible preparation technique helps to remove the bottleneck of nanomedicines including quality control, scale-up production and clinical translation. Acting as both carriers and cargos, the carrier-free PDNAs have an ultra-high or even 100% drug loading. In addition, combination therapies based on PDNAs could possibly address the most intractable problems in cancer treatment, such as tumor metastasis and drug resistance. In the present review, the latest development of PDNAs for cancer treatment is overviewed. First, PDNAs are classified according to the composition of drug molecules, and the assembly mechanisms are discussed. Furthermore, the co-delivery of PDNAs for combination therapies is summarized, with special focus on the improvement of therapeutic outcomes. Finally, future prospects and challenges of PDNAs for efficient cancer therapy are spotlighted.

The synergistic effect of chemo-photothermal therapies in SN-38-loaded gold-nanoshell-based colorectal cancer treatment

Aim: 7-Ethyl-10-hydroxycamptothecin (SN-38)-loaded gold nanoshells nanoparticles (HSP@Au NPs) were developed for combined chemo-photothermal therapy to treat colorectal cancer. Materials & methods: SN-38-loaded nanoparticles (HSP NPs) were prepared by the lyophilization-hydration method, and then developed into gold nanoshells. The nanoparticles were characterized and assessed for photothermal properties, cytotoxicity and hemocompatibility in vitro. In vivo anticancer activity was tested in a tumor mouse model. Results: The HSP@Au NPs (diameter 186.9 nm, zeta potential 33.4 mV) led to significant cytotoxicity in cancer cells exposed to a near-infrared laser. Moreover, the HSP@Au NP-mediated chemo-photothermal therapy displayed significant tumor growth suppression and disappearance (25% of tumor clearance rate) without adverse side effects in vivo. Conclusion: HSP@Au NPs may be promising in the treatment of colorectal cancer in the future.

Efficient Photoacoustic Imaging With Biomimetic Mesoporous Silica-Based Nanoparticles

Indocyanine green (ICG), a near-infrared (NIR) fluorescent dye approved by the Food and Drug Administration (FDA), has been extensively used as a photoacoustic (PA) probe for PA imaging. However, its practical application is limited by poor photostability in water, rapid body clearance, and non-specificity. Herein, we fabricated a novel biomimetic nanoprobe by coating ICG-loaded mesoporous silica nanoparticles with the cancer cell membrane (namely, CMI) for PA imaging. This probe exhibited good dispersion, large loading efficiency, good biocompatibility, and homologous targeting ability to Hela cells in vitro. Furthermore, the in vivo and ex vivo PA imaging on Hela tumor-bearing nude mice demonstrated that CMI could accumulate in tumor tissue and display a superior PA imaging efficacy compared with free ICG. All these results demonstrated that CMI might be a promising contrast agent for PA imaging of cervical carcinoma.

Design and construction of IR780- and EGCG-based and mitochondrial targeting nanoparticles and their application in tumor chemo-phototherapy

An integration combination of phototherapy and chemotherapy to treat carcinoma, solving the inner limitation of individual-modal chemical agent-based therapy or phototherapy, emerges to be a strategy with high prospects for achieving synergistic curative effects. The dye IR780-iodide (IR780) close to infrared radiation is a phototherapy agent with high prospects. However, it is limited in its clinical applications due to poor solubility in water. While epigallocatechin-3-gallate (EGCG), naturally resourced green tea polyphenol, has been extensively proven with intrinsic antitumor activity, but it is largely restricted by its low bioavailability in vivo. Hence, novel multiple-function nanoparticles comprising hyaluronic acid (HA) and IR780 were proposed to deliver EGCG, defined as EGCG@THSI nano-scale particles (EGCG@THSI NPs), thereby rapidly solving limitations of EGCG and IR780. Amphiphilic nano-scale carrier was prepared by triphenylphosphine (TPP), hyaluronic acid (HA), cystamine, and IR780, termed as TPP-HA-SS-IR780, and EGCG was loaded into the amphiphilic copolymer by self-assembly. TPP-HA-SS-IR780 endowed the as-synthesized EGCG@THSI NPs with excellent TPP-mediated mitochondrial-targeted and glutathione-triggered rapid drug release properties. As impacted by the integration of phototherapy and chemotherapy, the EGCG@THSI NPs under NIR laser irradiation showed a prominent anti-tumor effect. Taken together, this study presented a multiple-function nano-scale carrier platform with high prospects in improving the therapeutic efficacy of anti-carcinoma drugs.

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.

Amphiphilic small molecular mates match hydrophobic drugs to form nanoassemblies based on drug-mate strategy

Nanomedicine has made great progress in the targeted therapy of cancer. Here, we established a novel drug-mate strategy by studying the formulation of nanodrugs at the molecular level. In the drug-mate combination, the drug is a hydrophobic drug that is poorly soluble in water, and the mate is an amphiphilic small molecule (SMA) that has both hydrophilic and lipophilic properties. We proposed that the hydrophobic drug could co-assemble with a suitable SMA on a nanoscale without additive agents. The proof-of-concept methodology and results were presented to support our hypothesis. We selected five hydrophobic drugs and more than ten amphiphilic small molecules to construct a library. Through molecular dynamic simulation and quantum chemistry computation, we speculated that the formation of nanoassemblies was related to the binding energy of the drug-mate, and the drug-mate interaction must overcome drug-drug interaction. Furthermore, the obtained SF/VECOONa nanoassemblieswas selected as a model, which had an ultra-high drug loading content (46%), improved pharmacokinetics, increased bioavailability, and enhanced therapeutic efficacy. In summary, the drug-mate strategy is an essential resource to design exact SMA for many hydrophobic drugs and provides a reference for the design of a carrier-free drug delivery system.

Emerging strategies in developing multifunctional nanomaterials for cancer nanotheranostics

Cancer involves a collection of diseases with a common trait - dysregulation in cell proliferation. At present, traditional therapeutic strategies against cancer have limitations in tackling various tumors in clinical settings. These include chemotherapeutic resistance and the inability to overcome intrinsic physiological barriers to drug delivery. Nanomaterials have presented promising strategies for tumor treatment in recent years. Nanotheranostics combine therapeutic and bioimaging functionalities at the single nanoparticle level and have experienced tremendous growth over the past few years. This review highlights recent developments of advanced nanomaterials and nanotheranostics in three main directions: stimulus-responsive nanomaterials, nanocarriers targeting the tumor microenvironment, and emerging nanomaterials that integrate with phototherapies and immunotherapies. We also discuss the cytotoxicity and outlook of next-generation nanomaterials towards clinical implementation.

Constructing nanocomplexes by multicomponent self-assembly for curing orthotopic glioblastoma with synergistic chemo-photothermal therapy

The blood-brain barrier (BBB) is one of the major limitations of glioblastoma therapy in the clinic. Nanodrugs have shown great potential for glioblastoma therapy. Herein, we purposefully developed a multicomponent self-assembly nanocomplex with very high drug loading content for curing orthotopic glioblastoma with synergistic chemo-photothermal therapy. The nanocomplex consisted of self-assembled pH-responsive nanodrugs derived from amino acid-conjugated camptothecin (CPT) and canine dyes (IR783) coated with peptide Angiopep-2-conjugated copolymer of Ang-PEG-g-PLL. Specifically, the carrier-free nanocomplex exhibited a high drug loading content (up to 62%), good biocompatibility, and effective glioma accumulation ability. Moreover, the nanocomplex displayed good stability and pH-responsive behavior ex vivo. Both in vitro and in vivo results revealed that the nanocomplex could effectively cross the BBB and target glioma cells. Furthermore, the combination of chemotherapy and photothermal therapy of the nanocomplex achieved a better therapeutic effect, longer survival time, and minimized toxic side effects in orthotopic glioblastoma tumor-bearing nude mice. Overall, we modified the chemotherapeutic drug CPT so that it could self-assemble with other molecules into nanoparticles, which providing an alternative for the preparation of the carrier-free nanodrugs. The results highlighted the potential of self-assembly nanodrugs as a novel platform for effective glioblastoma therapy.

A NIR-triggered multifunctional nanoplatform mediated by Hsp70 siRNA for chemo-hypothermal photothermal synergistic therapy

Recently, hypothermal photothermal therapy (HPTT) seemed essential for the future clinical transformation of cancer optical therapies. However, at a lower working temperature, heat shock proteins (HSPs) seriously affect the anti-tumor effect of HPTT. This work reports a reasonable design of a dual-responsive nanoplatform for the synergistic treatment of chemotherapy and HPTT. We adopted a one-step method to wrap indocyanine green (ICG) into imidazole skeleton-8 (ZIF-8) and further loaded it with the chemotherapy drug doxorubicin (DOX). Furthermore, we introduced Hsp-70 siRNA to block the affection of HSPs at an upstream node, thereby avoiding the side effects of traditional heat shock protein inhibitors. The prepared ZIF-8@ICG@DOX@siRNA nanoparticles (ZID-Si NPs) could significantly improve the stability of siRNA to effectively down-regulate the expression of HSP70 protein during the photothermal therapy, thus realizing the pH-controlled and NIR-triggered release of the chemotherapeutical drug DOX. Moreover, tumors were also imaged accurately by ICG wrapped in ZID-Si nanoparticles. After the evaluation of the in vitro and in vivo photothermal effect as well as the anti-tumor activity, we found that the added Hsp-70 siRNA enhanced the synergistic anti-cancer activity of HPTT and chemotherapy. In summary, this work holds great potential in cancer treatment, and suggests better efficacy of synergistic chemo/HPTT than the single-agent therapy.

Self-assembly of peptide nanofibers for imaging applications

Pathological stimuli-responsive self-assembly of peptide nanofibers enables selective accumulation of imaging agent cargos in the stimuli-rich regions of interest. It provides enhanced imaging signals, biocompatibility, and tumor/disease accessibility and retention, thereby promoting smart, precise, and sensitive tumor/disease imaging both in vitro and in vivo. Considering the remarkable significance and recent encouraging breakthroughs of self-assembled peptide nanofibers in tumor/disease diagnosis, this reivew is herein proposed. We emphasize the recent advances particularly in the past three years, and provide an outlook in this field.

A carrier-free nanoparticle with dual NIR/acid responsiveness by co-assembly of enediyne and IR820 for combined PTT/chemotherapy

Combined photothermal therapy/chemotherapy by co-delivery of a photosensitizer (PS) and a chemotherapeutic drug has demonstrated great potential for cancer treatment. The intrinsic drawbacks of traditional drug delivery systems (DDSs), such as tedious synthetic procedures, side effects originated from the carrier materials, low loading efficiency, and uncontrolled drug release, however, have impaired their further advancement. On the other hand, enediyne antibiotics are highly cytotoxic toward cancer cells through the generation of lethal carbon radicals via thermal-induced cyclization, endowing them with great potential to achieve enhanced synergistic anticancer performance by incorporation with the photothermal effect of PS. To this end, a carrier-free and NIR/acid dual-responsive DDS was constructed for combined photothermal therapy/chemotherapy. The facile co-assembly of maleimide-based enediyne and PS IR820 was achieved in aqueous solution to give nanoparticles (EICN) with a hydrodynamic diameter of 90 nm and high stability. In vitro study confirmed the acid/NIR dual-responsive degradation and drug release, free radical generation and DNA-cleaving ability of EICN, which was accomplished by the corporation of enediyne and IR820 moieties. Further tests on HeLa cells verified the excellent synergistic anticancer performance of EICN including the improved cellular uptake, NIR-enhanced drug release, DNA damage and histone deacetylase inhibitor capacity. Overall, this carrier-free DDS with dual acid/NIR-responsivity would potentially provide new insights for the development of combined photothermal/chemotherapy.

PEGylated phospholipid micelles containing D-α-tocopheryl succinate as multifunctional nanocarriers for enhancing the antitumor efficacy of doxorubicin

The aim of this investigation is to clarify the effect of D-α-tocopheryl succinate (vitamin E succinate, VES) and distearoylphosphatidyl ethanolamine-poly(ethylene glycol) (DSPE-PEG) on the encapsulation and controlled release of doxorubicin (DOX) in nano-assemblies and their consequences on the anti-tumor efficacy of DOX. DOX molecules were successfully loaded into the hybrid micelles with VES and DSPE-PEG (VDPM) via thin-film hydration method, exhibiting a small hydrodynamic particle size (~30 nm) and a weak negative zeta potential of around -5 mv. The obtained DOX-loaded VDPM2 displayed retarded DOX release at pH of 7.4, while substantially accelerated drug release at acidic pH of 5.0. Furthermore, the DOX-loaded VDPM2 exhibited substantially slower drug release rate at pH 7.4 compared with the drug-loaded VDPM1 or DPM preparation, benefiting for decreasing the premature DOX release during blood circulation. In vitro cell experiment indicated that DOX-loaded micelles (DPM, VDPM1 and VDPM2) improved the cellular uptake of DOX in 4T1 and MDA-MB-231 cells. The existence of VES component in the structure of DOX-loaded micelles had no obvious influence on the subcellular distribution of the encapsulated DOX molecules. Furthermore, the DOX-loaded VDPM2 exhibited more pronounced cytotoxicity to 4T1 and MDA-MB-231 cancerous cells compared with DOX-loaded DPM and free DOX solution. The hybrid nanocarriers including VES and DSPE-PEG selectively induced intracellular ROS accumulation and increased level of cytoplasmic calcium ion in cancerous cells by interacting with mitochondria and endoplasmic reticulum, bringing about the improved cytotoxicity of DOX. In vivo antitumor efficacy investigation of DOX-loaded VDPM2 against 4T1 xenograft-bearing mice displayed satisfied therapeutic activity with negligible systemic toxicity, as evidenced by the histological analysis and change of body weight. The proposed DOX-loaded VDPM preparation, as a mulifunctional chemotherapeutic nanomedicine system, holds great potential and bright prospect for clinical tumor therapy.

Strategies and applications of covalent organic frameworks as promising nanoplatforms in cancer therapy

Cancer nanomedicine is the best option to face the limits of conventional chemotherapy and phototherapy methods, and thus the intensive quest for new nanomaterials to improve therapeutic efficacy and safety is still underway. Owing to their low density, well-defined structures, large surface area, finely tunable pore size, and metal ion free features, covalent organic frameworks (COFs) have been extensively studied in many research fields. The recent great interest in nanoscale COFs to improve the properties of bulk COFs has led to broadening of their applicability in the biomedical field, such as nanocarriers with an outstanding loading capacity and efficient delivery of therapeutic agents, smart theranostic nanoplatforms with excellent stability, high ROS generation, light-to-heat conversion capabilities, and different response and diagnostic characteristics. The COFs and related nanoplatforms with a wide variety of designability and functionalization have opened up a new avenue for exciting opportunities in cancer therapy. Herein we review the state-of-the-art technical and scientific developments in this emerging field, focusing on the overall progress addressed so far in building versatile COF-based nanoplatforms to enhance chemotherapy, photodynamic/photothermal therapy, and combination. Future perspectives for achieving the synergistic effect of cancer elimination and clinical translation are further discussed to motivate future contributions and explore new possibilities.

An iron oxide nanoparticle-based transdermal nanoplatform for dual-modal imaging-guided chemo-photothermal therapy of superficial tumors

Transdermal delivery is an attractive strategy for treating superficial tumors. However, the applications of existing transdermal systems have been limited by low transdermal efficiency and poor therapeutic outcomes. Here, we develop a transdermal nanoplatform (+)T-SiDs, based on superparamagnetic iron oxide core, surface-modified with cationic lipids, transdermal enhanced peptide TD, and 1,1'-dioctadecyl-3,3,3',3'-tetramethylindotricarbocyanine iodide (DiR), and loaded with doxorubicin. The (+)T-SiDs compositions enable MR/NIR dual-modal imaging guided synergistic chemo-photothermal therapy to superficial tumors treatment via transdermal delivery. The (+)T-SiDs exhibit good stability, efficient cellular uptake, pH/photothermal responsive drug release, and high photothermal conversion efficiency (47.45%). Importantly, the transdermal delivery of (+)T-SiDs is significantly enhanced by TD functionalization. In vivo MR/NIR imaging shows that the (+)T-SiDs exhibit high transdermal efficiency and specificity in localization to the tumor site. Moreover, in comparison with individual chemo- or photothermal therapies, the combination of chemo-photothermal therapy exhibits more efficient tumor inhibition effects. This work presents a new transdermal treatment nanoplatform for dual-modal imaging-guided chemo-photothermal therapy of superficial tumors, with efficient tumor eradication and low systemic toxicity thus offering strong potential for clinical adoption. STATEMENT OF SIGNIFICANCE: Transdermal delivery is an attractive strategy for treating superficial tumors. However, a highly efficient transdermal nanoplatform remains to be developed. Herein, we designed a multifunctional transdermal nanoplatform for dual-modal imaging-guided chemo-photothermal therapy of superficial tumors, comprised of a super-paramagnetic iron oxide (SPIO) nanoparticle, which can act as an MRI contrast agent and photothermal agent; a transdermal enhanced peptide (TD) and cationic lipids, which can accelerate skin penetration; and a NIR dye (DiR) and doxorubicin (DOX), which can achieve a synergistic enhanced chemo-photothermal therapy with NIR imaging ability. The transdermal nanoplatform achieved efficient tumor eradication and low systemic toxicity, thus offering strong potential for clinical adoption.

Shuttle-Shape Carrier-Free Platinum-Coordinated Nanoreactors with O2 Self-Supply and ROS Augment for Enhanced Phototherapy of Hypoxic Tumor

The synergistic nanotheranostics of reactive oxygen species (ROS) augment or phototherapy has been a promising method within synergistic oncotherapy. However, it is still hindered by sophisticated design and fabrication, lack of a multimodal synergistic effect, and hypoxia-associated poor photodynamic therapy (PDT) efficacy. Herein, a kind of porous shuttle-shape platinum (IV) methylene blue (Mb) coordination polymer nanotheranostics-loaded 10-hydroxycamptothecin (CPT) is fabricated to address the abovementioned limitations. Our nanoreactors possess spatiotemporally controlled O2 self-supply, self-sufficient singlet oxygen (1O2), and outstanding photothermal effect. Once they are taken up by tumor cells, nanoreactors as a cascade catalyst can efficiently catalyze degradation of the endogenous hydrogen peroxide (H2O2) into O2 to alleviate tumor hypoxia. The production of O2 can ensure enhanced PDT. Subsequently, under both stimuli of external red light irradiation and internal lysosomal acidity, nanoreactors can achieve the on-demand release of CPT to augment in situ mitochondrial ROS and highly efficient tumor ablation via phototherapy. Moreover, under the guidance of near-infrared (NIR) fluorescent imaging, our nanoreactors exhibit strongly synergistic potency for treatment of hypoxic tumors while reducing damages against normal tissues and organs. Collectively, shuttle-shape platinum-coordinated nanoreactors with augmented ROS capacity and enhanced phototherapy efficiency can be regarded as a novel tumor theranostic agent and further promote the research of synergistic oncotherapy.

Recent advances in nanoparticles mediated photothermal therapy induced tumor regression

Photothermal therapy (PTT) is a minimally invasive procedure for treating cancer. The two significant prerequisites of PTT are the photothermal therapeutic agent (PTA) and near-infrared radiation (NIR). The PTA absorbs NIR, causing hyperthermia in the malignant cells. This increased temperature at the tumor microenvironment finally results in tumor cell damage. Nanoparticles play a crucial role in PTT, aiding in the passive and active targeting of the PTA to the tumor microenvironment. Through enhanced permeation and retention effect and surface-engineering, specific targeting could be achieved. This novel delivery tool provides the advantages of changing the shape, size, and surface attributes of the carriers containing PTAs, which might facilitate tumor regression significantly. Further, inclusion of surface engineering of nanoparticles is facilitated through ligating ligands specific to overexpressed receptors on the cancer cell surface. Thus, transforming nanoparticles grants the ability to combine different treatment strategies with PTT to enhance cancer treatment. This review emphasizes properties of PTAs, conjugated biomolecules of PTAs, and the combinatorial techniques for a better therapeutic effect of PTT using the nanoparticle platform.

Indocyanine green dye based bimodal contrast agent tested by photoacoustic/fluorescence tomography setup

Multimodal imaging systems are in high demand for preclinical research, experimental medicine, and clinical practice. Combinations of photoacoustic technology with other modalities including fluorescence, ultrasound, MRI, OCT have been already applied in feasibility studies. Nevertheless, only the combination of photoacoustics with ultrasound in a single setup is commercially available now. A combination of photoacoustics and fluorescence is another compelling approach because those two modalities naturally complement each other. Here, we presented a bimodal contrast agent based on the indocyanine green dye (ICG) as a single signalling compound embedded in the biocompatible and biodegradable polymer shell. We demonstrate its remarkable characteristics by imaging using a commercial photoacoustic/fluorescence tomography system (TriTom, PhotoSound Technologies). It was shown that photoacoustic signal of the particles depends on the amount of dye loaded into the shell, while fluorescence signal depends on the total amount of dye per particle. For the first time to our knowledge, a commercial bimodal photoacoustic/fluorescence setup was used for characterization of ICG doped polymer particles. Additionally, we conducted cell toxicity studies for these particles as well as studied biodistribution over time in vivo and ex vivo using fluorescent imaging. The obtained results suggest a potential for the application of biocompatible and biodegradable bimodal contrast agents as well as the integrated photoacoustic/fluorescence imaging system for preclinical and clinical studies.

Erythrocyte membrane bioengineered nanoprobes via indocyanine green-directed assembly for single NIR laser-induced efficient photodynamic/photothermal theranostics

Traditional combinational photodynamic therapy (PDT) and photothermal therapy (PTT) were limited in clinical therapy of cancer due to exceptionally low drug payload and activation by light with separate wavelengths. We have accidentally discovered that zinc phthalocyanine (ZNPC, a typical hydrophobic photosensitizer) and indocyanine green (ICG, a clinically approved fluorescence probe) could be co-assembled into carrier-free nanodrugs (almost 100 wt%) for single NIR laser-induced efficient PDT/PTT. Interestingly, ICG could act as "transformers" for modulating the geometric shape of ZNPC/ICG co-assembling structures from needle-like/spindle-like structure via cubic structure finally to spherical structure. Unfortunately, the nanodrugs suffered from rapid immune clearance. The ZNPC-ICG nanoprobes were further embedded into the erythrocyte membrane (RBC)-camouflaged framework. The designed ZNPC-ICG@RBC could be efficiently accumulated within the tumor sites (continue for ~60 h) and rapidly internalized into cancer cells upon laser irradiation rather than macrophage RAW264.7 cells. Compared with the free ZnPC or ICG, the biomimetic ZNPC-ICG@RBC nanoprobes exhibited amplified therapeutic effects by simultaneously producing ROS and hyperthermia, thereby synergistically improving antitumor efficiency and eliminating the tumors without any regrowth under the guidance of fluorescence imaging. The co-delivery of ZnPC and ICG via a biomimetic carrier-free system might be a promising strategy for bimodal phototherapy of cancer.

Dual-Stimuli-Responsive Nanotheranostics for Dual-Targeting Photothermal-Enhanced Chemotherapy of Tumor

Stimuli-responsive nanotheranostics have been widely explored for precision medicine. Here, we developed a pH/light dual-stimuli-responsive nanotheranostic agent for biological/physical dual-targeting photothermal-enhanced chemotherapy of U87MG tumor. This nanotheranostic agent was composed of the RGD (Arg-Gly-Asp) peptide, melanin-coated magnetic nanoparticles (MMNs), doxorubicin (DOX), and indocyanine green (ICG), denoted as RMDI. The tumor accumulation of RMDI was simultaneously improved through biological active targeting by RGD and physical magnetic targeting by an external magnetic field at tumor tissues, which was proven by in vivo photoacoustic/magnetic resonance/fluorescence (PA/MR/FL) trimodal imaging. Under dual stimuli of the tumor acidic microenvironment and laser irradiation, both DOX and ICG were released in a controlled fashion, demonstrating impressive therapeutic outcomes against U87MG tumor both in vitro and in vivo, respectively. Owing to the synergistic photothermal/chemotherapy, the dual-stimuli-responsive and dual-targeting nanotheranostic agent completely ablated U87MG tumor in vivo without any tumor recurrence and biotoxicity. This nanotheranostic agent exhibited great potential in multimodal imaging-guided synergistic therapy of cancer.

Self-recognizing and stimulus-responsive carrier-free metal-coordinated nanotheranostics for magnetic resonance/photoacoustic/fluorescence imaging-guided synergistic photo-chemotherapy

Carrier-free nanotheranostics directly assembled by using clinically used photosensitizers and chemotherapeutic drugs are a promising alternative to tumor theranostics. However, the weak interaction-driven assembly still suffers from low structural stability against disintegration, lack of targeting specificity, and poor stimulus-responsive property. Moreover, almost all exogenous ligands possess no therapeutic effect. Enlightened by the concept of metal-organic frameworks, we developed a novel self-recognizing metal-coordinated nanotheranostic agent by the coordination-driven co-assembly of photosensitizer indocyanine green (ICG) and chemo-drug methotrexate (MTX, also served as a specific "targeting ligand" towards folate receptors), in which ferric (FeIII) ions acted as a bridge to tightly associate ICG with MTX. Such carrier-free metal-coordinated nanotheranostics with high dual-drug payload (∼94 wt%) not only possessed excellent structural and physiological stability, but also exhibited prolonged blood circulation. In addition, the nanotheranostics could achieve the targeted on-demand drug release by both stimuli of internal lysosomal acidity and external near-infrared laser. More importantly, the nanotheranostics could self-recognize the cancer cells and selectively target the tumors, and therefore they decreased toxicity to normal tissues and organs. Consequently, the nanotheranostics showed strongly synergistic potency for tumor photo-chemotherapy under the precise guidance of magnetic resonance/photoacoustic/fluorescence imaging, thereby achieving highly effective tumor curing efficiency. Considering that ICG and bi-functional MTX are approved by the Food and Drug Administration, and FeIII ions have high biosafety, the self-recognizing and stimulus-responsive carrier-free metal-coordinated nanotheranostics may hold potential applications in tumor theranostics.

A carrier-free metal-coordinated dual-photosensitizers nanotheranostic with glutathione-depletion for fluorescence/photoacoustic imaging-guided tumor phototherapy

As a promising noninvasive tumor treatment modality, dual phototherapy, including photodynamic therapy (PDT) and photothermal therapy (PTT), has drawn extensive research interest in imaging-guided synergistic antitumor treatment. However, developing a high-efficient phototherapeutic agent is still a huge challenge, since single photosensitizer often suffers from the insufficient photothermal conversion efficiency (PCE) or low reactive oxygen species (ROS) productivity. Moreover, the overexpression of reductive glutathione (GSH) in tumor cells also severely compromises PDT efficiency. Here, inspired by the glutathione oxidase activity of high-valent transition metal ions, we designed a copper-coordinated nanotheranostic (PhA@NanoICG) by the coordination-driven co-assembly of photothermal-agent indocyanine green (ICG) and photodynamic-agent pheophorbide A (PhA), in which Cu²⁺ acted as a bridge to tightly associate ICG with PhA. Such carrier-free metal-coordinated nanotheranostics exhibited ultra-high dual-photosensitizers co-loading (~96.74 wt%) and excellent structural stability. Notably, NanoICG significantly increase the PCE of ICG via J-aggregation induced UV-vis absorption red-shift. Once PhA@NanoICG accumulated in tumor sites, they could be disassembled triggered by the weakly acidic and highly reducible tumor microenvironment. Moreover, the Cu²⁺ can deplete intracellular GSH and impair cellular antioxidant defense system, reducing the unnecessary ROS consumption caused by glutathione. Under fluorescence/photoacoustic imaging-guided laser irradiation, local hyperthermia and ROS were generated to induce tumor cells apoptosis. The in vitro and in vivo experiments consistently confirm that PhA@NanoICG could induce remarkable tumor inhibition through self-enhanced PTT and PDT, which may pave a new way for cancer therapy.

An Activatable Theranostic Nanoprobe for Dual-Modal Imaging-Guided Photodynamic Therapy with Self-Reporting of Sensitizer Activation and Therapeutic Effect

Intelligent systems that offer traceable cancer therapy are highly desirable for precision medicine. Although photodynamic therapy (PDT) has been approved in the clinic for decades, determining where the tumor is, when to irradiate, and how long to expose to light still confuse the clinicians. Patients are always suffering from the phototoxicity of the photosensitizer in nonmalignant tissues. Herein, an activatable theranostic agent, ZnPc@TPCB nanoparticles (NPs), is prepared by doping a photosensitizer, ZnPc, with an aggregation-induced emission probe, TPCB. The assembled or disassembled ZnPc@TPCB NPs in various phases have behaved differently in fluorescence intensity, photoacoustic (PA) signals, and PDT efficiency. The intact nanoparticles are non-emissive in aqueous media while showing strong PA signals and low PDT efficiency, which can eliminate the phototoxicity and self-monitor their distribution and image the tumors' location. Disassembling of the NPs leads to the release of ZnPc and its red fluorescence turn-on to self-report the photosensitizer's activation. Upon light irradiation, the reactive oxygen species (ROS) generated by ZnPc can induce cell apoptosis and activate the ROS sensor, TPCB, which will yield intense orange-red fluorescence and instantly predict the therapeutic effect. Moreover, enhanced PDT efficacy is achieved via the GSH-depleting adjuvant quinone methide produced by the activated TPCB. The well-designed ZnPc@TPCB NPs have shown promising potential for finely controlled PDT with good biosafety and broad application prospects in individual therapy, which may inspire the development of precision medicine.

Advances in Indocyanine Green-Based Codelivery Nanoplatforms for Combinatorial Therapy

Indocyanine green (ICG), a near-infrared (NIR) agent with an excellent imaging performance, has captivated enormous interest from researchers owing to its excellent therapeutic and imaging abilities. Although various nanoplatforms-based drug delivery systems (DDS) with the ability to overcome the clinical limitations of ICG has been reported, ICG-medicated conventional cancer diagnosis and photorelated therapies still lack in exhibiting the therapeutic efficacy, resulting in incomplete or partly tumor elimination. In the view of addressing these concerns, various DDSs have been engineered for the efficient codelivery of combined therapeutic agents with ICG, aiming to achieve promising therapeutic results due to multifunctional imaging-guided synergistic antitumor effects. In this article, we will systematically review currently available nanoplatforms based on polymers, inorganic, proteins, and metal-organic frameworks (MOFs), among others, for codelivery of ICG along with other therapeutic agents, providing a foundation for future clinical development of ICG. In addition, codelivery systems for ICG and different mechanism-based therapeutic agents will be illustrated. In summary, we conclude the review with the challenges and perspectives of ICG-based versatile nanoplatforms in detail.

Using copper sulfide nanoparticles as cross-linkers of tumor microenvironment responsive polymer micelles for cancer synergistic photo-chemotherapy

Photo-chemotherapy presents promising therapeutic effects in cancer treatment. Photo-thermal and chemotherapeutic agents are generally delivered independently or jointly by drug carriers, such as polymer micelles. A polymer micelle is one type of widely researched drug carrier. However, there is a disassembly risk for polymer micelles under excessive dilution in blood circulation, leading to the premature release of payloads from the micelles and finally resulting in undesirable toxic side effects. Herein, amino-PEG decorated copper sulfide nanoparticles (CuS NPs) with photothermal effect were applied as a cross-linker to enhance polymeric micelles' stability and to provide photothermal therapy in the meanwhile. The micelles were prepared using a pH/reductive responsive polymer, poly(ε-caprolactone)-ss-poly(2-(diisopropylamino)ethyl methacrylate/glycidyl methacrylate/2-methylacrylloxyethyl phosphorylcholine (PCL-SS-P(DPA/GMA/MP)), abbreviated as DGM. Cross-linked micelles (DGM-CuS) exhibited high photothermal transformation efficiency and excellent stability against dilution, as well as pH and redox responsive drug release. Under near-infrared laser irradiation, the cell cytotoxicity of doxorubicin-loaded micelles DGM-CuS@DOX and DGM-CuS@DOX-P (DGM-CuS@DOX modified by peptides) increased by 17.1 times and 69.2 times correspondingly compared to that without laser irradiation. All of the solid 4T1 tumors disappeared, and tumor metastases were merely observed in the major organs of the tumor-bearing mice after administration of DGM-CuS@DOX and DGM-CuS@DOX-P with irradiation. In this synergistic therapy system, CuS NPs play double roles of a photothermal agent and a micelle cross-linker. The strategy of utilizing nanoparticles as cross-linkers is newly reported, which offers new insight for combination therapy.

Erythrocyte membrane-camouflaged carrier-free nanoassembly of FRET photosensitizer pairs with high therapeutic efficiency and high security for programmed cancer synergistic phototherapy

Phototherapy has been intensively investigated as a non-invasive cancer treatment option. However, its clinical translation is still impeded by unsatisfactory therapeutic efficacy and severe phototoxicity. To achieve high therapeutic efficiency and high security, a nanoassembly of Forster Resonance Energy Transfer (FRET) photosensitizer pairs is developed on basis of dual-mode photosensitizer co-loading and photocaging strategy. For proof-of-concept, an erythrocyte-camouflaged FRET pair co-assembly of chlorine e6 (Ce6, FRET donor) and 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindotricarbocyanine iodide (DiR, FRET acceptor) is investigated for breast cancer treatment. Notably, Ce6 in the nanoassemby is quenched by DiR and could be unlocked for photodynamic therapy (PDT) only when DiR is photobleached by 808-nm laser. As a result, Ce6-caused phototoxicity could be well controlled. Under cascaded laser irradiation (808–660 nm), tumor-localizing temperature rise following laser irradiation on DiR not only induces tumor cell apoptosis but also facilitates the tumor penetration of NPs, relieves tumor hypoxia, and promotes the PDT efficacy of Ce6. Such FRET pair-based nanoassembly provides a new strategy for developing multimodal phototherapy nanomedicines with high efficiency and good security.

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Biomimetic carrier-free nanoassembly developed by FRET photosensitizer pairs.

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Dual-mode co-loading and photocaging strategy for programmed cancer synergistic phototherapy.

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Avoiding the ROS-induced off-target phototoxicity by the intelligently controlled ROS activation.

Tumor acidity-responsive carrier-free nanodrugs based on targeting activation via ICG-templated assembly for NIR-II imaging-guided photothermal–chemotherapy

Novel tumor microenvironment-driven self-targeting supramolecular nanodrugs via ICG-templated small-molecule self-assembly for NIR-II imaging-guided synergistic photothermal–chemotherapy.

Novel albumin-binding photothermal agent ICG-IBA-RGD for targeted fluorescent imaging and photothermal therapy of cancer

In this work, we present a novel photothermal agent ICG-IBA-RGD based on albumin-binding strategy for enhanced tumor targeting imaging and photothermal therapy. In vitro and in vivo experiments demonstrated that ICG-IBA-RGD exhibits excellent photothermal conversion capability and high tumor ablation efficiency.

In this work, we present a novel photothermal agent ICG-IBA-RGD based on albumin-binding strategy for enhanced tumor targeting imaging and photothermal therapy.

A Simple Aggregation-Induced Emission Nanoprobe with Deep Tumor Penetration for Hypoxia Detection and Imaging-Guided Surgery in Vivo

The pan-cancer detection and precise visualization of tiny tumors in surgery still face great challenges. As tumors grow aggressively, hypoxia is a common feature of solid tumors and has supplied a general way for detecting tumors. Herein, we report a simple aggregation-induced emission nanoprobe-TPE-4NE-O that can specifically switch on their fluorescence in the presence of cytochrome P450 reductase, a reductase which is overexpressed under hypoxia conditions. The probe can selectively light up the hypoxia cells and has shown enhanced deep tumor penetration via charge conversion both in vitro and in vivo. After being modified with FA-DSPE-PEG, higher tumor uptake can be seen and FA-DSPE/TPE-4NE-O showed specific visualization to the hypoxia cancer cells. Excitingly, much brighter fluorescence was accumulated at the tumors in the FA-DSPE/TPE-4NE-O group, even though the tumor was as small as 2.66 mm. The excellent performance of FA-DSPE/TPE-4NE-O in detecting tiny tumors has made it possible for imaging-guided tumor resection. More importantly, the probe exhibited good biocompatibility with negligible organ damage and eliminated a hemolysis risk. The simple but promising probe has supplied a new strategy for pan-cancer detection and tiny tumor visualization, which have shown great potential in clinical translation.

Carrier-Free Platinum Nanomedicine for Targeted Cancer Therapy

Numerous nanomedicines have been developed to improve the efficiency and safety of conventional anticancer drugs; however, the complexities in carrier materials and functional integration make it challenging to promote these candidates for clinical translation. In this study, a facile method to prepare carrier-free anticancer nanodrug with inherent bone targeting and osteoclastogenesis inhibition capabilities is reported. Phytic acid, a naturally occurring and nontoxic product, is reacted with cisplatin to form uniform nanoparticles of different sizes. The prepared nanoparticles possess high drug loading and pH-responsive drug release behaviors. Phytic acid in the nanomedicine ensures high bone targeting and osteoclastogenesis inhibition, and the released platinum drugs triggered by tumor extracellular acidity eradicate tumor cells. The nanomedicine around 100 nm shows high anticancer activity and much reduced side effects in a subcutaneous breast cancer model when compared with cisplatin. In addition, it shows high accumulation at osteolytic lesions, and efficiently inhibits tumor growth and tumor-associated osteolysis in a bone metastatic breast cancer model. Here, a facile and efficient strategy to prepare carrier-free nanomedicines with high anticancer drug loading, inherent bone targeting, and osteoclast inhibitory activities for cancer therapy is provided.

Fabrication of doxorubicin-gated mesoporous polydopamine nanoplatforms for multimode imaging-guided synergistic chemophotothermal therapy of tumors

A versatile theranostic agent that integrated with therapeutic and diagnostic functions is extremely essential for cancer theranostic. Herein, a multifunctional theranostic nanoplatform (PFP@MPDA-DOX) based on perfluoropentane (PFP) encapsulated mesoporous polydopamine (MPDA) is elaborately designed, followed by gating of drug doxorubicin (DOX) for preventing cargo leaking. The MPDA with pH-responsive biodegradation behavior was served as nanocarrier, which also endows the nanoplatform with a large cavity for PFP filling. The nanoparticles were then gated with DOX molecule by Michael addition and/or Schiff base reaction to shield the leaking of PFP during the blood circulation before the tumor tissue is reached. Also, such nanotheranostic exhibits high photothermal conversion efficiency of 45.6%, which can act as an intelligent nanosystem for photothermal therapy (PTT) and photoacoustic (PA) imaging. Moreover, the liquid-gas phase transition of PFP arising upon exposure to an 808 nm laser and thus produced the bubbles for ultrasound (US) imaging. The subsequent PFP@MPDA-DOX-mediated synergetic chemotherapy (contributed by the DOX gatekeeper) and PTT (contributed by the MPDA) shows excellent anticancer activity, which has been systematically evaluated both in vitro and in vivo. All these positive results certify that the facile incorporation of the antitumor drug gatekeeper and MPDA into one theranostic nanoplatform shows general potential for multimode PA/US imaging and combination chemotherapy/PTT of tumors.

Advances and perspectives in carrier-free nanodrugs for cancer chemo-monotherapy and combination therapy

Nanocarrier-based drug delivery systems hold impressive promise for biomedical application because of their excellent water dispersibility, prolonged blood circulation time, increased drug accumulation in tumors, and potential in combination therapeutics. However, most nanocarriers suffer from low drug-loading efficiency, poor therapeutic effectiveness, potential systematic toxicity, and unstable metabolism. As an alternative, carrier-free nanodrugs, completely formulated with one or more drugs, have attracted increasing attention in cancer therapy due to their advantage of improved pharmacodynamics/pharmacokinetics, reduced toxicity, and high drug-loading. In recent years, carrier-free nanodrugs have contributed to progress in a variety of therapeutic modalities. In this review, different common strategies for carrier-free nanodrugs preparation are first summarized, mainly including nanoprecipitation, template-assisted nanoprecipitation, thin-film hydration, spray-drying technique, supercritical fluid (SCF) technique, and wet media milling. Then we describe the recently reported carrier-free nanodrugs for cancer chemo-monotherapy or combination therapy. The advantages of anti-cancer drugs combined with other chemotherapeutic, photosensitizers, photothermal, immunotherapeutic or gene drugs have been demonstrated. Finally, a future perspective is introduced to highlight the existing challenges and possible solutions toward clinical application of currently developed carrier-free nanodrugs, which may be instructive to the design of effective carrier-free regimens in the future.

Self-Distinguishing and Stimulus-Responsive Carrier-Free Theranostic Nanoagents for Imaging-Guided Chemo-Photothermal Therapy in Small-Cell Lung Cancer

Lack of tumor targeting and low drug payload severely impedes various nanoagents further employed in small-cell lung cancer (SCLC). Therefore, how to develop a new targeting ligand and enhance drug payload has been an urgent need for SCLC therapy. Herein, we first sift and verify that capreomycin (Cm) has a high affinity toward CD56 receptors overexpressed on SCLC cells. Motivated by the concept of self-targeted drug delivery, Cm is selected as the specific targeting ligand toward CD56 receptors and chemodrug doxorubicin (Dox) is adopted to be covalently linked via the redox-responsive disulfide linkage. The synthesized self-distinguishing prodrug (Dox-ss-Cm) and FDA-approved photosensitizer indocyanine green (ICG) as structural motifs can be self-assembled into theranostic nanoagents (ICG@Dox-ss-Cm NPs) within an aqueous solution. Such carrier-free nanoagents with high drug payload can exert targeted on-demand drug release under multiple stimuli of intracellular lysosomal acidity, glutathione (GSH), and an external near-infrared (NIR) laser. Besides, our nanoagents can be specifically self-targeted to SCLC sites in vivo and self-distinguishing via SCLC cells in vitro; thus, they decrease the undesirable effects on normal tissues and organs. Further in vitro and in vivo studies uniformly confirm that such nanoagents show highly synergistic effects for SCLC chemo-photothermal therapy (PTT) under the precise guidance of NIR fluorescence (NIRF)/photoacoustic (PA) imaging. Taken together, our work can provide a novel and promising strategy for the targeted treatment of SCLC.

Injectable zwitterionic thermosensitive hydrogels with low-protein adsorption and combined effect of photothermal-chemotherapy

Injectable hydrogels have been developed as biomedical materials in various fields but the biofouling on their surface limits applications in vivo. In this work, a zwitterionic structure was introduced into an injectable hydrogel based on thermosensitive nanogels to overcome the foreign body reaction. The hydrodynamic diameter of the resultant poly(N-isopropylacrylamide-co-sulfobetaine methacrylate) (PNS) nanogels was ca. 105 nm. The aqueous dispersion with a high content of PNS nanogels showed a flowable sol state at room temperature, and turned into a hydrogel in situ at ∼36 °C due to the thermosensitivity of the PNS nanogels. In particular, the resulting hydrogel exhibited lower biofouling both in vitro and in vivo in comparison with similar hydrogels without a zwitterionic structure. Polydopamine nanoparticles (PDA NPs) as a photothermal agent and an anti-tumour drug could be easily co-loaded in the injectable hydrogel. Under near-infrared (NIR) irradiation for 10 min, the temperature of the PNS system containing PDA NPs could reach ca. 38 °C. The drug release from the in situ-forming hydrogel could be accelerated by NIR laser irradiation, and showed a sustainable release behavior and adjustability. The results of intratumoral injection of the as-prepared injectable hydrogel containing PDA NPs and an anti-tumour drug showed significant anticancer effects combining photothermal therapy and local chemotherapy. This constructed injectable zwitterionic thermosensitive hydrogel is easy to use with the advantage of low-fouling and may become a promising platform for various biomedical applications.

Quantitative Study of the Nonlinearly Enhanced Photoacoustic/Photothermal Effect by Strong LSPR-Coupled Nanoassemblies

The extensive exploration of the collective optical and thermal effects for localized surface plasmon resonance (LSPR)-coupled nanoassemblies has propelled much recent research and development in fields of photoacoustic (PA) imaging and photothermal (PT) therapy, while the rational design and proper engineering of these assemblies under quantitative guidance is still a highly challenging task. In this work, by utilizing the finite element analysis (FEA) method and taking gold nanochains as example, the authors quantitatively studied the coupling optical/thermal response of the nanoassemblies and the associated nonlinearly enhanced PA/PT effect. Results show that compared with their individuals, the strong electromagnetic/thermal coupling between the individuals of the nanoassemblies results in a several-time enhancement of the per-particle-weighted optical absorption, consequential thermal field enhancement, and initial PA pressure, resulting in nonlinearly amplified energy conversion from incident light to heat and PA waves. The dependence of the nonlinear PA/PT enhancement on the assembly chain length, the size of the individuals, the interparticle distance, and the size uniformity of the building blocks is quantitatively discussed. PA experiments on gold nanochains and gold nanospheres are performed to validate the proposition, and the experiments well silhouetted the theoretical discussion. This work paves the way for the rational construction and optimization of plasmonic nanoassemblies with improved PA/PT conversion efficiency.

Binary blended co-delivery nanoparticles with the characteristics of precise pH-responsive acting on tumor microenvironment

Although combined chemotherapy had achieved the ideal efficacy in clinical anti-cancer therapeutic, the issues that need to be addressed are non-targeting and toxic-side effects of small molecule chemical drug (SMCD). In this study, we designed and prepared a novel binary blended co-delivered nanoparticles (BBCD NPs) with pH-responsive feature on tumor microenvironment. The BBCD NPs consists of two kind of drug-loaded NPs, in one of which carboxymethyl chitosan (CMC) and Poly (lactic-co-glycolic acid) (PLGA) were chosen as delivery carrier to load anti-cancer drug vincristine (VCR), named CMC-PLGA-VCR NPs (or CPNP_VCR); and in the other of which methoxy poly(ethylene glycol)-poly(β-amino ester) (mPEG-PAE) were chosen as delivery carrier to load anti-fibrotic drug pirfenidone (PFD), named mPEG-PAE-PFD NPs (or PPNP_PFD). Then, the two types of NPs (CPNP_VCR and PPNP_PFD) were physically mixed in mass ratios to form BBCD NPs, which was named CPNP_VCR&PPNP_PFD. CPNP_VCR&PPNP_PFD had good encapsulation efficiency and loading capacity, and the particle size distribution was uniform. In cytotoxicity experiments and non-contact co-culture studies in vitro, the model drugs loaded in CPNPVCR&PPNPPFD could respectively target cancer cell and cancer associated fibroblast (CAF) owing to the precise pH-sensitive drug release in the pharmacological targets and show stronger synergism than that of the combined treatment of two free drugs. As a modularity and assemble ability feature in design, BBCD NPs would have the advantages on the terms of concise on preparation process, controllable on quality standard, stable in natural environment storage. The research results can provide scientific evidence for the further development of a novel drug co-delivery system with multi-type cell targets.

Photo-triggered release of doxorubicin from liposomes formulated by amphiphilic phthalocyanines for combination therapy to enhance antitumor efficacy

Multidrug combination therapy based on drug delivery systems (DDSs) has great potential for cancer treatment. Stimuli-sensitive DDSs further enhance therapeutic efficacy by providing controllable drug delivery. Herein, the phospholipid compound DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine) was used to construct thermosensitive liposomes to load the photosensitizer ZnPc(PEG)₄ (zinc phthalocyanine substituted by tetraethylene glycol) for molecular imaging, and photodynamic and photothermal therapy, together with doxorubicin (DOX) for chemotherapy. Interestingly, ZnPc(PEG)₄ as an amphipathic molecule was found to be important in the construction of the liposomes, and it provided liposomes with improved stability. The thus-obtained liposomes ZnPc(PEG)₄:DOX@LiPOs were demonstrated to have enhanced ROS production capacity, heat generation properties and a photo-triggered doxorubicin release effect, and, in cellular experiments, increased cytotoxicity and apoptotic cell proportions, compared to ZnPc(PEG)₄@LiPOs and DOX@LiPOs. ZnPc(PEG)₄ loaded in lipid bilayers showed stronger intracellular ROS production ability compared to free ZnPc(PEG)₄. In vivo studies indicated that ZnPc(PEG)₄:DOX@LiPOs exhibited enhanced tumor accumulation, increased anti-cancer effects and reduced liver retention. These photo-triggered liposomes constructed by the photosensitizer ZnPc(PEG)₄ can also be used to package other cargo for combined target tumor therapy and molecular imaging.

Ultralong-Circulating and Self-Targeting "Watson-Crick A = T"-Inspired Supramolecular Nanotheranostics for NIR-II Imaging-Guided Photochemotherapy

A carrier-free theranostic nanodrug directly coassembled using a NIR probe and a chemotherapeutic drug is a promising alternative for cancer theranostics. Nevertheless, this nanodrug still faces the limitations of short blood circulation and inefficient tumor accumulation/tumoral cellular uptake in vivo. Meanwhile, most exogenous targeting ligands and poly(ethylene glycol) have no therapeutic effect. Herein, we designed an ultralong-circulating and self-targeting nanodrug by an ordered supramolecular coassembly of indocyanine green (ICG), methotrexate (MTX, chemotherapeutic drug and cancer-cell-specific ligand), and clofarabine (CA). Notably, CA, as a surfactant-like chemotherapeutic drug, was introduced into the initial ICG-MTX coassembly by "Watson-Crick A = T-inspired" hydrogen-bond-driven sequential assembly with MTX. This carrier-free theranostic nanodrug with exceptionally high drug payload (100 wt %) not only showed superior serum stabilities but also displayed ultralong blood circulation (>7 days), enabling efficient accumulation at tumor sites. Moreover, our nanodrugs could be self-recognized by cancer cells and release the drugs on demand through lysosomal acidity and external laser stimulus. Under NIR-II imaging guidance, high-efficiency tumor ablation via synergistic photothermal-chemotherapy could be achieved in one treatment cycle while preventing the tumor recurrence. Our ultralong-circulating and self-recognizing carrier-free theranostic nanodrug based on the "drug-delivering-drug" strategy might have the potential for clinical theranostic application.

Bioactive MOFs Based Theranostic Agent for Highly Effective Combination of Multimodal Imaging and Chemo-Phototherapy

Bioactive metal-organic frameworks (bio-MOFs) built from biofunctional metal ions and linkers show a new strategy to construct multifunctional theranostic platforms. Herein, a bio-MOF is synthetized via the self-assembling of Fe³⁺ ions and doxorubicin hydrochloride (DOX) molecules. Then, through a stepwise assembly strategy, another bio-MOFs structure consisting of Gd³⁺ ions and 1,3,5-benzenetricarboxylic acid (H₃ BTC) is wrapped on the surfaces of Fe-DOX nanoparticles, followed by adsorbing photosensitizer indocyanine green (ICG). Specifically, the Gd-MOF shell structure can not only act as a contrast agent for magnetic resonance imaging (MRI), but also provides protection for Fe-DOX cores, controlling the release of DOX. The photoacoustic and photothermal imaging (PAI and PTI) methods are successfully introduced to the platform by loading ICG, providing potential applications for multimodal biological imaging. The in vitro and in vivo outcomes indicate that the Fe-DOX@Gd-MOF-ICG nanoplatform exhibits outstanding synergistic antitumor performance via MR/PA/PT imaging guided chemotherapy, photothermal and photodynamic combination therapy. The work may encourage further exploration of bio-MOFs based multifunctional theranostic platforms for multimodal imaging guided compound antitumor therapy, which will open an avenue of MOFs toward biological applications.

A computer-aided chem-photodynamic drugs self-delivery system for synergistically enhanced cancer therapy

The therapeutic strategy that gives consideration to the combination of photodynamic therapy and chemotherapy, has emerged as a potential development of effective anti-cancer medicine. Nevertheless, co-delivery of photosensitizers (PSs) and chemotherapeutic drugs in traditional carriers still remains great limitations due to low drug loadings and poor biocompatibility. Herein, we have utilized a computer-aided strategy to achieve a desired carrier-free self-delivery of pyropheophorbide a (PPa, a common PS) and podophyllotoxin (PPT, a classical chemotherapeutic drug) for synergistic cancer therapy. First, the computational simulation method identified the similar molecular sizes and rigid molecular structures between two drugs molecules. Based on the molecular docking, the intermolecular interactions were found to include π-π stackings, hydrophobic interactions and hydrogen bonds. Next, both drugs could co-assemble into nanoparticles (NPs) via one-step nanoprecipitation method. The various spectral experiments (UV, IR and FL) were conducted to evaluate the formation mechanism of spherical NPs. Moreover, in vitro and in vivo experiments systematically demonstrated that PPT/PPa NPs not only showed better cellular uptake efficiency, stronger cytotoxicity and higher accumulation in tumor sites, but also exhibited synergistic antitumor effect in female BALB/C bearing-4T1 tumor mice. Such a computer-aided design strategy of chem-photodynamic drugs self-delivery systems pave the way for efficient synergistic cancer therapy.