Mitochondria-Targeting Polydopamine Nanocomposites as Chemophotothermal Therapeutics for Cancer

Polydopamine nanoplatform with near infrared light and pH dual stimuli-responsive for chemo-photothermal cancer therapy

Photothermal agent accompanying with thermally responsive materials, displays well controlled drug release property, which is well-received as an outstanding design strategy for simultaneous photothermal/chemotherapy in cancer. Cyanine dye, as the prestigious photothermal agent has shown great potential due to its preeminent near-infrared absorbance and excellent thermal conversion efficiency. However, their inherent defect such as inferior photothermal stability, high leakage risk and poor therapy efficacy limit their further application in cancer therapy. Hence, a facile and universal strategy to make up these deficiencies is developed. Chemotherapeutic drug DOX and cyanine dye were loaded into polydopamine (PDA) nanoparticles. The PDA encapsulation dramatically improved the photothermal stability of cyanine dye. Attributed by the PDA structure feature, the thermo-sensitive small molecule glyamine (Gla) is introduced into the PDA surface to lessen leakage. The Gla can form a dense encapsulation layer on the dopamine surface through hydrogen bond. This newly fabricated Cyanine/DOX@PDA-Gla nanopaltform is characterized with NIR light/pH dual-responsive property, high NIR photothermal conversion performance and fluorescence guided chemo-photothermal therapy.

A cascade nanoplatform for the regulation of the tumor microenvironment and combined cancer therapy

Recently, disulfiram (DSF), an anti-alcoholism drug, has attracted increasing biomedical interest due to its anticancer effects. However, the anticancer activity of DSF is Cu(II)-dependent and it is extremely unstable, which severely hinders its clinical translation. Herein, we report the fabrication of a multifunctional nanoplatform (MCDGF) that can improve the stability of diethyldithiocarbamate (DTC), a main metabolite of DSF, by modifying the aryl boronic ester group to form a prodrug (DQ), and also realize the in situ generation of Cu(DTC)2, which relies on a cascade reaction. The delivered Cu/DQ induces immunogenic cell death (ICD) and powerfully enhances immune responses of cytotoxic T lymphocytes (CTLs) and the infiltration of dendritic cells as well as T cells. Furthermore, the grafted glucose oxidase (GOx) decomposes glucose, thus "starving" the cancer cells and providing H2O2 for the production of Cu(DTC)2. More importantly, H2O2 significantly promotes the polarization of macrophages to the anti-tumor subtype. The nano-carrier "mesoporous polydopamine (MPDA)" also displays a good photothermal therapeutic effect. The nanoplatform-integrated chemotherapy, starvation therapy, photothermal therapy, and immunotherapy synergistically stimulated CTL activation and M1 macrophage polarization. Taken together, the as-prepared nanoplatform could regulate the tumor immune microenvironment and eliminate cancer with combined cancer therapy, which will offer a promising strategy for cancer treatment and promote the clinical application of DSF in breast cancer.

Rapid Mitochondria Targeting by Arginine-Terminated, Sub-10 nm Nanoprobe via Direct Cell Membrane Penetration

Although mitochondria have been identified as a potential therapeutic target for the treatment of various diseases, inefficient drug targeting to mitochondria is a major limitation for related therapeutic applications. In the current approach, drug loaded nanoscale carriers are used for mitochondria targeting via endocytic uptake. However, these approaches show poor therapeutic performance due to inefficient drug delivery to mitochondria. Here, we report a designed nanoprobe that can enter the cell via a nonendocytic approach and label mitochondria within 1 h. The designed nanoprobe is <10 nm in size and terminated with arginine/guanidinium that offers direct membrane penetration followed by mitochondria targeting. We found five specific criteria that need to be adjusted in a nanoscale material for mitochondria targeting via the nonendocytic approach. They include <10 nm size, functionalization with arginine/guanidinium, cationic surface charge, colloidal stability, and low cytotoxicity. The proposed design can be adapted for mitochondria delivery of drugs for efficient therapeutic performance.

Heterojunction structured BiOCl-Bi2S3 nanosheets as mitochondria-targeted near-infrared photothermal and photodynamic therapy agent

Mitochondria-targeted phototherapy, especially combined photothermal therapy (PTT) and photodynamic therapy (PDT), has been regarded as an attractive strategy for the treatment of tumor. In this study, a facile approach to prepare two-dimensional (2D) BiOCl-Bi₂S₃ nanostructures was developed, where Bi₂S₃ quantum dots were doped in/on the ultrathin BiOCl nanosheets, forming a p-n heterojunction. The BiOCl-Bi₂S₃ shows favorable photothermal conversion efficiency (32%) and synergistically reactive oxygen species (ROS) generating capability under near-infrared (NIR) irradiation. Moreover, the conjugation of synthetic targeting ligand to the surface of BiOCl-Bi₂S₃ endows the heterojunction effective tumor targeting ability and selective mitochondrial accumulation. The combined cancer targeting ability and synergistic PTT/PDT permit enhanced cooperative phototherapeutic efficiency of the 2D heterojunction. This study provides an attractive way for designing new class of heterostructure materials for potential applications in subcellular-targeted phototherapy.

Subcellular delivery of lipid nanoparticles to endoplasmic reticulum and mitochondria

Primarily responsible for the biogenesis and metabolism of biomolecules, endoplasmic reticulum (ER) and mitochondria are gradually becoming the targets of therapeutic modulation, whose physiological activities and pathological manifestations determine the functional capacity and even the survival of cells. Drug delivery systems with specific physicochemical properties (passive targeting), or modified by small molecular compounds, polypeptides, and biomembranes demonstrating tropism for ER and mitochondria (active targeting) are able to reduce the nonselective accumulation of drugs, enhancing efficacy while reducing side effects. Lipid nanoparticles feature high biocompatibility, diverse cargo loading, and flexible structure modification, which are frequently used for subcellular organelle-targeted delivery of therapeutics. However, there is still a lack of systematic understanding of lipid nanoparticle-based ER and mitochondria targeting. Herein, we review the pathological significance of drug selectively delivered to the ER and mitochondria. We also summarize the molecular basis and application prospects of lipid nanoparticle-based ER and mitochondria targeting strategies, which may provide guidance for the prevention and treatment of associated diseases and disorders. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Biology-Inspired Nanomaterials > Lipid-Based Structures Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Diagnostic Tools > In Vivo Nanodiagnostics and Imaging.

PDA-Based Drug Delivery Nanosystems: A Potential Approach for Glioma Treatment

Glioma is characterized by high mortality and low postoperative survival. Despite the availability of various therapeutic approaches and molecular typing, the treatment failure rate and the recurrence rate of glioma remain high. Given the limitations of existing therapeutic tools, nanotechnology has emerged as an alternative treatment option. Nanoparticles, such as polydopamine (PDA)-based nanoparticles, are embodied with reliable biodegradability, efficient drug loading rate, relatively low toxicity, considerable biocompatibility, excellent adhesion properties, precisely targeted delivery, and strong photothermal conversion properties. Therefore, they can further enhance the therapeutic effects in patients with glioma. Moreover, polydopamine contains pyrocatechol, amino and carboxyl groups, active double bonds, catechol, and other reactive groups that can react with biofunctional molecules containing amino, aldehyde, or sulfhydryl groups (main including, self-polymerization, non-covalent self-assembly, π-π stacking, electrostatic attraction interaction, chelation, coating and covalent co-assembly), which form a reversible dynamic covalent Schiff base bond that is extremely sensitive to pH values. Meanwhile, PDA has excellent adhesion capability that can be further functionally modified. Consequently, the aim of this review is to summarize the application of PDA-based NPs in glioma and to acquire insight into the therapeutic effect of the drug-loaded PDA-based nanocarriers (PDA NPs). A wealthy understanding and argument of these sides is anticipated to afford a better approach to develop more reasonable and valid PDA-based cancer nano-drug delivery systems. Finally, we discuss the expectation for the prospective application of PDA in this sphere and some individual viewpoints.

Neuroprotective Effect of Ultrasound Triggered Astaxanthin Release Nanoparticles on Early Brain Injury After Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is a fatal disease. Within 72 h of SAH, the intracranial blood-brain barrier (BBB) is destroyed, and the nerve cells have responses such as autophagy, apoptosis, and oxidative stress. Antioxidation is an essential treatment of SAH. Astaxanthin (ATX) induces cells' antioxidant behaviors by regulating related signal pathways to reduce the damage of brain oxidative stress, inflammation, and apoptosis. Because of its easy degradability and low bioavailability, ATX is mainly encapsulated with stimulus-responsive nanocarriers to improve its stability, making it rapidly release in the brain and efficiently enter the lesion tissue. In this study, the ultrasonic cavitation agent perfluorocarbon (PFH), ATX, and fluorescent dye IR780 were loaded with polydopamine (PDA) to prepare a US triggered release nanoparticles (AUT NPs). The core-shell structure of AUT NPs formed a physical barrier to improve the bioavailability of ATX. AUT NPs have high ATX loading capacity and US responsiveness. The experimental results show that the AUT NPs have high stability in the physiological environment. Both US and pH stimuli can trigger the release. Under US, PFH breaks through the rigid shell. The structure of AUT NPs is destroyed in situ, releasing the loaded drugs into neuronal cells to realize the antioxidant and antiapoptotic effects. The in vivo experiment results show that the AUT NPs have good biosafety. They release the drugs in the brain under stimuli. The in vivo treatment results also show that AUT NPs have an excellent therapeutic effect. This approach presents an experimental basis for the establishment of Innovative SAH treatments.

Dual Blood-Brain Barrier-Glioma Targeting Peptide-Poly(levodopamine) Hybrid Nanoplatforms as Potential Near Infrared Phototheranostic Agents in Glioblastoma

Combined chemo-phototherapy for boosting the efficacy of individual modalities by synergism for antiglioma treatments is in its embryonic stage and far away from effective clinical translation. Herein, moving a step closer, we recommend a facile stratagem to fabricate smart biocompatible and biodegradable multifunctional nanoplatforms comprising inherently fluorescent poly(levodopamine) nanoparticles (FLs) co-loaded with doxorubicin (DOX) and indocyanine green (ICG). The designed near-infrared (NIR) phototheranostic agents upon NIR laser irradiation helped precipitate combined chemo-phototherapy [both photothermal therapy (PTT) and photodynamic therapy (PDT)] and optical imaging under one roof. Excellent glioma-targeting ability was allocated to the nanoplatforms by conjugating them with a novel chimeric therapeutic peptide with glioma homing and antiglioma dual functionality. Further, DOX/ICG/peptide co-loaded nanoplatforms (FLDIPs) exhibited triggered drug release in response to multiple stimuli. Studies performed in 2D C6 glioma cells and 3D spheroids exhibited superior combined chemo-PDT/PTT effects (∼94% killing in cells and ∼87% in spheroids) of the designed FL based nanoplatforms compared to individual therapeutic components. Herein, the FL based multifunctional nanoplatforms with active targeting ability and stimuli responsive drug release behavior will further help in nullifying chemotherapy based adverse effects and mitigate chemo-resistance by adopting a combinatorial approach.

A PDA-DTC/Cu-MnO2 nanoplatform for MR imaging and multi-therapy for triple-negative breast cancer treatment

Herein, a multi-functional nanoplatform (PDA-DTC/Cu-MnO2) was established, which has been employed for MR imaging-guided multi-therapy (CDT, PTT and chemotherapy) for cancer treatment. The in vitro and in vivo results confirmed that the biocompatible nanoplatform could significantly induce tumor cell death and inhibit tumor growth.

Smart Design of Nanomaterials for Mitochondria-Targeted Nanotherapeutics

Mitochondria are the powerhouse of cells. They are vital organelles that maintain cellular function and metabolism. Dysfunction of mitochondria results in various diseases with a great diversity of clinical appearances. In the past, strategies have been developed for fabricating subcellular-targeting drug-delivery nanocarriers, enabling cellular internalization and subsequent organelle localization. Of late, innovative strategies have emerged for the smart design of multifunctional nanocarriers. Hierarchical targeting enables nanocarriers to evade and overcome various barriers encountered upon in vivo administration to reach the organelle with good bioavailability. Stimuli-responsive nanocarriers allow controlled release of therapeutics to occur at the desired target site. Synergistic therapy can be achieved using a combination of approaches such as chemotherapy, gene and phototherapy. In this Review, we survey the field for recent developments and strategies used in the smart design of nanocarriers for mitochondria-targeted therapeutics. Existing challenges and unexplored therapeutic opportunities are also highlighted and discussed to inspire the next generation of mitochondrial-targeting nanotherapeutics.

Amplified Photoacoustic Signal and Enhanced Photothermal Conversion of Polydopamine-Coated Gold Nanobipyramids for Phototheranostics and Synergistic Chemotherapy

Light-responsive nanoprobes were suffering from the threat of high-dose laser irradiation, and it was important for constructing new nanoprobes for safe and efficient phototheranostics. Here, polydopamine (PDA)-coated gold nanobipyramids (AuNBPs@PDA) were synthesized for amplified photoacoustic (PA) signal and enhanced photothermal conversion with low-dose laser irradiation and then doxorubicin (DOX)-loaded AuNBPs@PDA-DOX nanoprobes were constructed for PA imaging-guided synergistic photothermal therapy (PTT) and chemotherapy. The AuNBPs@PDA nanoparticles possessed higher photothermal conversion efficiency (42.07%) and stronger PA signal than those of AuNBP nanoparticles, and the AuNBPs@PDA-DOX nanoprobes showed dual-responsive DOX release of pH and photothermal stimulation. With low-dose laser irradiation (1.0 W/cm²) and low-concentration AuNBPs@PDA-DOX (60 μg/mL), the 4T1 cell viability was reduced to about 5%, owing to the combination of PTT and chemotherapy, compared with 42.3% of single chemotherapy and 25.3% of single PTT. Moreover, by modeling 4T1 tumor-bearing nude mice, in vivo PA imaging was achieved and the tumors were completely inhibited, demonstrating the excellent synergistic effect of PTT/chemotherapy. Therefore, the developed AuNBPs@PDA-DOX nanoprobes can be used for phototheranostics and synergistic chemotherapy, achieving low-dose laser irradiation and high-efficient visualized theranostics.

A polydopamine-based platform for anti-cancer drug delivery

Cancer is the second leading cause of death in the world with around 9.6 million deaths in 2018, approximately 70% of which occurred in the middle- and low-income countries; moreover, the economic impact of cancer is significant and escalating day by day. The total annual economic cost of cancer treatment in 2010 was estimated at approximately US$ 1.16 trillion. Researchers have explored cancer mitigation therapies such as chemo-thermal therapy, chemo-photothermal therapy and photodynamic-photothermal therapy. These combinational therapies facilitate better control on the tunability of the carrier for effectively diminishing cancer cells than individual therapies such as chemotherapy, photothermal therapy and targeted therapy. All these therapies come under novel drug delivery systems in which anti-cancer drugs attack the cancerous cells due to various stimuli (e.g. pH, thermal, UV, IR, acoustic and magnetic)-responsive properties of the anti-cancer drug carriers. Compared to conventional drug delivery systems, the novel drug delivery systems have several advantages such as targeted drug release, sustained and consistent blood levels within the therapeutic window, and decreased dosing frequency. Among the numerous polymeric carriers developed for drug delivery, polydopamine has been found to be more suitable as a carrier for these drug delivery functions due to its easy and cost-effective fabrication, excellent biocompatibility, multi-drug carrier capacity and stimuli sensitivity. Therefore, in this review, we have explored polydopamine-based carriers for anti-cancer drug delivery systems to mitigate cancer and simultaneously discussed basic synthesis routes for polydopamine.

Facile formulation of near-infrared light-triggered hollow mesoporous silica nanoparticles based on mitochondria targeting for on-demand chemo/photothermal/photodynamic therapy

The incorporation of chemo/photothermal/photodynamic therapy in subcellular organelles such as mitochondria has attracted extensive attention recently. Here, we designed mitochondria-targeted hollow mesoporous silica nanoparticles (THMSNs) loaded biocompatible phase-change material L-menthol (LM) via a facile method. Meanwhile, antitumor drug doxorubicin (DOX) and near-infrared (NIR) dye indocyanine green (ICG) approved by FDA were simultaneously encapsulated into THMSNs, denoted as THMSNs@LMDI, which showed NIR radiation triggered capacity for cancer treatment. With the mitochondria-targeted ability of triphenylphosphine, the resulting THMSNs@LMDI showed evidently improved cellular internalization and specific accumulation in mitochondria. Under NIR irradiation, the versatile ICG would be bound to simultaneously produce photodynamic and photothermal therapy. Meanwhile, in view of the solid-liquid phase transition feature of gatekeeper LM, THMSNs@LMDI provided a platform for NIR-mediated temperature-responsive DOX release. As a matter of course, these smart subcellular organelle-THMSNs could serve as an effective drug delivery platform for site-specific on-demand chemo/photothermal/photodynamic therapy of cancer.

Boosting Cancer Therapy with Organelle-Targeted Nanomaterials

The ultimate goal of cancer therapy is to eliminate malignant tumors while causing no damage to normal tissues. In the past decades, numerous nanoagents have been employed for cancer treatment because of their unique properties over traditional molecular drugs. However, lack of selectivity and unwanted therapeutic outcomes have severely limited the therapeutic index of traditional nanodrugs. Recently, a series of nanomaterials that can accumulate in specific organelles (nucleus, mitochondrion, endoplasmic reticulum, lysosome, Golgi apparatus) within cancer cells have received increasing interest. These rationally designed nanoagents can either directly destroy the subcellular structures or effectively deliver drugs into the proper targets, which can further activate certain cell death pathways, enabling them to boost the therapeutic efficiency, lower drug dosage, reduce side effects, avoid multidrug resistance, and prevent recurrence. In this Review, the design principles, targeting strategies, therapeutic mechanisms, current challenges, and potential future directions of organelle-targeted nanomaterials will be introduced.

Mitochondria-Targeted Polydopamine Nanocomposite with AIE Photosensitizer for Image-Guided Photodynamic and Photothermal Tumor Ablation

Photodynamic therapy (PDT) and photothermal therapy (PTT) are two kinds of treatment for tumors. Herein, a new aggregation-induced emission (AIE)gen (MeO-TPE-indo, MTi) is synthesized with a D-π-A conjugated structure. MTi, which has an electron donor and an acceptor on a tetraphenylethene (TPE) conjugated skeleton, can induce the effective generation of reactive oxygen species (ROS) for PDT. With the guide of the indolium group, MTi can target and image mitochondrion selectively. In order to get good dispersion in water and long-time retention in tumors, MTi is modified on the surface of polydopamine nanoparticles (PDA NPs) to form the nanocomposite (PDA-MeO-TPE-indo, PMTi) by π-π and hydrogen interactions. PMTi is a nanoscale composite for imaging-guided PDT and PTT in tumor treatment, which is constructed with AIEgens and PDA for the first time. The organic functional molecules are combined with nanomaterials for building a multifunctional diagnosis and treatment platform by utilizing the advantages of both sides.

Improving the Phototherapeutic Efficiencies of Molecular and Nanoscale Materials by Targeting Mitochondria

Mitochondria-targeted cancer phototherapy (PT), which works by delivering photoresponsive agents specifically to mitochondria, is a powerful strategy to improve the phototherapeutic efficiency of anticancer treatments. Mitochondria play an essential role in cellular apoptosis, and are relevant to the chemoresistance of cancer cells. Furthermore, mitochondria are a major player in many cellular processes and are highly sensitive to hyperthermia and reactive oxygen species. Therefore, mitochondria serve as excellent locations for organelle-targeted phototherapy. In this review, we focus on the recent advances of mitochondria-targeting materials for mitochondria-specific PT. The combination of mitochondria-targeted PT with other anticancer strategies is also summarized. In addition, we discuss both the challenges currently faced by mitochondria-based cancer PT and the promises it holds.