Glycyrrhetinic Acid Functionalized Graphene Oxide for Mitochondria Targeting and Cancer Treatment In Vivo

Development of Graphene-Based Materials with the Targeted Action for Cancer Theranostics

The review summarises the prospects in the application of graphene and graphene-based nanomaterials (GBNs) in nanomedicine, including drug delivery, photothermal and photodynamic therapy, and theranostics in cancer treatment. The application of GBNs in various areas of science and medicine is due to the unique properties of graphene allowing the development of novel ground-breaking biomedical applications. The review describes current approaches to the production of new targeting graphene-based biomedical agents for the chemotherapy, photothermal therapy, and photodynamic therapy of tumors. Analysis of publications and FDA databases showed that despite numerous clinical studies of graphene-based materials conducted worldwide, there is a lack of information on the clinical trials on the use of graphene-based conjugates for the targeted drug delivery and diagnostics. The review will be helpful for researchers working in development of carbon nanostructures, material science, medicinal chemistry, and nanobiomedicine.

Nanocarriers address intracellular barriers for efficient drug delivery, overcoming drug resistance, subcellular targeting and controlled release

The cellular barriers are major bottlenecks for bioactive compounds entering into cells to accomplish their biological functions, which limits their biomedical applications. Nanocarriers have demonstrated high potential and benefits for encapsulating bioactive compounds and efficiently delivering them into target cells by overcoming a cascade of intracellular barriers to achieve desirable therapeutic and diagnostic effects. In this review, we introduce the cellular barriers ahead of drug delivery and nanocarriers, as well as summarize recent advances and strategies of nanocarriers for increasing internalization with cells, promoting intracellular trafficking, overcoming drug resistance, targeting subcellular locations and controlled drug release. Lastly, the future perspectives of nanocarriers for intracellular drug delivery are discussed, which mainly focus on potential challenges and future directions. Our review presents an overview of intracellular drug delivery by nanocarriers, which may encourage the future development of nanocarriers for efficient and precision drug delivery into a wide range of cells and subcellular targets.

Functional electrospun nanofibers: fabrication, properties, and applications in wound-healing process

Electrostatic spinning as a technique for producing nanoscale fibers has recently attracted increasing attention due to its simplicity, versatility, and loadability. Nanofibers prepared by electrostatic spinning have been widely studied, especially in biomedical applications, because of their high specific surface area, high porosity, easy size control, and easy surface functionalization. Wound healing is a highly complex and dynamic process that is a crucial step in the body's healing process to recover from tissue injury or other forms of damage. Single-component nanofibers are more or less limited in terms of structural properties and do not fully satisfy various needs of the materials. This review aims to provide an in-depth analysis of the literature on the use of electrostatically spun nanofibers to promote wound healing, to overview the infinite possibilities for researchers to tap into their biomedical applications through functional composite modification of nanofibers for advanced and multifunctional materials, and to propose directions and perspectives for future research.

A glycyrrhetinic acid-iridium(III) conjugate as a theranostic NIR probe for hepatocellular carcinoma with mitochondrial-targeting ability

Hepatocellular carcinoma (HCC) is a major contributor to global mortality rates, but current treatment options have limitations. Advanced theranostics are needed to effectively integrate diagnosis and therapeutic of HCC. Glycyrrhetinic acid (GA) has abundant binding sites with glycyrrhetinic acid receptors (GA-Rs) on the surface of HCC cells and has also been reported to possess ligands with mitochondrial-targeting capability but with limited efficacy. Herein, we report a near-infrared (NIR) luminescent theranostic complex 1 through conjugating an iridium(III) complex to GA, which exhibits the desired photophysical properties and promotes mitochondrial-targeting capability. Complex 1 was selectively taken up by HepG2 liver cancer cells and was imaged within mitochondria with NIR emission. Complex 1 targeted mitochondria and opened mitochondrial permeability transition pores (MPTPs), resulting in ROS accumulation, mitochondrial damage, disruption of Bax/Bcl-2 equilibrium, and tumor cell apoptosis, resulting in significantly improved anticancer activity compared to GA. This work offers a methodology for developing multifunctional theranostic probes with amplified specificity and efficacy.

Glycyrrhetinic Acid Receptor-Mediated Zeolitic Imidazolate Framework-8 Loaded Doxorubicin as a Nanotherapeutic System for Liver Cancer Treatment

In this study, we designed and developed a DOX nanodrug delivery system (PEG-GA@ZIF-8@DOX) using ZIF-8 as the carrier and glycyrrhetinic acid (GA) as the targeting ligand. We confirmed that DOX was loaded and PEG-GA was successfully modified on the surface of the nanoparticles. The in vitro release profile of the system was investigated at pH 5.0 and 7.4. The cellular uptake, in vitro cytotoxicity, and lysosomal escape characteristics were examined using HepG2 cells. We established an H22 tumor-bearing mouse model and evaluated the in vivo antitumor activity. The results showed that the system had a uniform nanomorphology. The drug loading capacity was 11.22 ± 0.87%. In acidic conditions (pH 5.0), the final release rate of DOX was 57.73%, while at pH 7.4, it was 25.12%. GA-mediated targeting facilitated the uptake of DOX by the HepG2 cells. PEG-GA@ZIF-8@DOX could escape from the lysosomes and release the drug in the cytoplasm, thus exerting its antitumor effect. When the in vivo efficacy was analyzed, we found that the tumor inhibition rate of PEG-GA@ZIF-8@DOX was 67.64%; it also alleviated the loss of the body weight of the treated mice. This drug delivery system significantly enhanced the antitumor effect of doxorubicin in vitro and in vivo, while mitigating its toxic side effects.

Application of graphene oxide in tumor targeting and tumor therapy

Graphene oxide (GO), as a kind of two-dimensional sp2 carbon nanomaterials, has attracted great attention in many fields in the past decade. Due to its unique physical and chemical properties, GO is showing great promise in the field of biomedicine. For GO, all the atoms on its surface are exposed to the surface with ultra-high specific surface area, and a variety of groups on the surface, such as carboxyl, hydroxyl and epoxy groups, can effectively bind/load various biomolecules. Due to the availability of these groups, GO also possesses excellent hydrophilicity and biocompatibility for the modification of the desired biocompatible molecules or polymers on the surface of GO. The nano-network structure and hydrophobicity of GO enable it to load a large number of hydrophobic drugs containing benzene rings and it has been widely used as a multi-functional nano-carrier for chemotherapeutic drug or gene delivery. This review article will give an in-depth overview of the synthesis methods of GO, the advantages and disadvantages of GO used in nano-drug delivery system, the research progress of GO as a stimulus-responsive nano-drug carrier, and the application of these intelligent systems in cancer treatment.

Single-Atom Nanoenzyme-Based Autoluminescence System for Cancer Cell Imaging and Mitochondrial-Targeted Therapy

The autoluminescence nanoplatform based on a single-atom catalyst has the potential to achieve accurate tumor diagnosis and treatment. Taking advantage of this, glycyrrhetinic acid (GA) and chitosan-modified single Fe-N-C atom catalysts (SAF NPs) loaded with luminol-curcumin (Cur) were fabricated (SAF-LCCG). Once delivered to the tumor, this autoluminescence SAF-LCCG could target the mitochondria to restrain tumor metastasis and promote the production of hydrogen peroxide (H2O2). Then, SAF NPs with Fenton-like properties could actively utilize intracellular H2O2 to produce ·OH for chemodynamic therapy. After that, excess ·OH and H2O2 were transmitted to luminol to emit blue-violet chemiluminescence (CL) for cancer cell imaging. Synchronously, light was transferred to Cur to produce reactive oxygen species (ROS) which realized photodynamic therapy. Besides, Cur could be served as a chemotherapeutic drug to enhance intracellular ROS for penetrating therapy. More importantly, the massive accumulation of ROS in cancer cells can promote the CL intensity of luminol, which realized the cyclic ROS amplification. This autoluminescence nanoplatform was developed for accurate cancer cell imaging, effective inhibition of tumor metastasis, and synergistic and penetrated treatment of tumors.

Graphene oxide nanoarchitectures in cancer therapy: Drug and gene delivery, phototherapy, immunotherapy, and vaccine development

The latest advancements in oncology involves the creation of multifunctional nanostructures. The integration of nanoparticles into the realm of cancer therapy has brought about a transformative shift, revolutionizing the approach to addressing existing challenges and limitations in tumor elimination. This is particularly crucial in combating the emergence of resistance, which has significantly undermined the effectiveness of treatments like chemotherapy and radiotherapy. GO stands as a carbon-derived nanoparticle that is increasingly finding utility across diverse domains, notably in the realm of biomedicine. The utilization of GO nanostructures holds promise in the arena of oncology, enabling precise transportation of drugs and genetic material to targeted sites. GO nanomaterials offer the opportunity to enhance the pharmacokinetic behavior and bioavailability of drugs, with documented instances of these nanocarriers elevating drug accumulation at the tumor location. The GO nanostructures encapsulate genes, shielding them from degradation and facilitating their uptake within cancer cells, thereby promoting efficient gene silencing. The capability of GO to facilitate phototherapy has led to notable advancements in reducing tumor progression. By PDT and PTT combination, GO nanomaterials hold the capacity to diminish tumorigenesis. GO nanomaterials have the potential to trigger both cellular and innate immunity, making them promising contenders for vaccine development. Additionally, types of GO nanoparticles that respond to specific stimuli have been applied in cancer eradication, as well as for the purpose of cancer detection and biomarker diagnosis. Endocytosis serves as the mechanism through which GO nanomaterials are internalized. Given these advantages, the utilization of GO nanomaterials for tumor elimination comes highly recommended.

Metal-organic framework decorated with glycyrrhetinic acid conjugated chitosan as a pH-responsive nanocarrier for targeted drug delivery

Stimulus-responsive nanomaterials have become a hot spot in controllable drug delivery systems researches owing to their spatiotemporal controllable properties based on the differences between tumor microenvironment and normal tissue. Herein, iron (III) carboxylate metal-organic framework nanoparticles coated with glycyrrhetinic acid-chitosan conjugate (MIL-101/GA-CS) were successfully fabricated and acted as the pH-responsive and target-selective system to deliver doxorubicin (DOX) for hepatocellular carcinoma (HCC) therapy. The prepared nanocarrier possess the advantages of uniform size, comparable drug loading efficiency (28.89 %), and superior pH-dependent controlled drug release (DOX release of 2.74 % and 89.18 % within 72 h at pH 7.4 and 5.5, respectively). In vitro cytotoxicity assays showed that the drug-loaded nanocarriers exhibited excellent inhibitory effects on HepG2 cells due to the sustained release of DOX, while the nanocarriers showed no significant toxicity. Furthermore, cell uptake experiments demonstrated that MIL-101-DOX/GA-CS could target HepG2 cells based on receptor-dependent internalization of glycyrrhetinic acid-receptors-mediated (GA-receptors). In vitro 3D hepatoma cell microspheres experiments showed that MIL-101-DOX/GA-CS had excellent penetration and tumor killing ability. Therefore, MIL-101-DOX/GA-CS nanoparticles have a prospective application in cancer therapy as a pH-responsive controlled drug delivery system.

Mitochondrial-targeted nanoparticles: Delivery and therapeutic agents in cancer

Mitochondria are the powerhouses of cells and modulate the essential metabolic functions required for cellular survival. Various mitochondrial pathways, such as oxidative phosphorylation or production of reactive oxygen species (ROS) are dysregulated during cancer growth and development, rendering them attractive targets against cancer. Thus, the delivery of antitumor agents to mitochondria has emerged as a potential approach for treating cancer. Recent advances in nanotechnology have provided innovative solutions for overcoming the physical barriers posed by the structure of mitochondrial organelles, and have enabled the development of efficient mitochondrial nanoplatforms. In this review, we examine the importance of mitochondria during neoplastic development, explore the most recent smart designs of nano-based systems aimed at targeting mitochondria, and highlight key mitochondrial pathways in cancer cells.

Mitochondria-Targeting Polyprodrugs to Overcome the Drug Resistance of Cancer Cells by Self-Amplified Oxidation-Triggered Drug Release

The multi-drug resistance (MDR) of cancers is one of the main barriers for the success of diverse chemotherapeutic methods and is responsible for most cancer deaths. Developing efficient approaches to overcome MDR is still highly desirable for efficient chemotherapy of cancers. The delivery of targeted anticancer drugs that can interact with mitochondrial DNA is recognized as an effective strategy to reverse the MDR of cancers due to the relatively weak DNA-repairing capability in the mitochondria. Herein, we report on a polyprodrug that can sequentially target cancer cells and mitochondria using folic acid (FA) and tetraphenylphosphonium (TPP) targeting moieties, respectively. They were conjugated to the terminal groups of the amphiphilic block copolymer prodrugs composed of poly[oligo(ethylene glycol) methyl ether methacrylate] (POEGMA) and copolymerized monomers containing cinnamaldehyde (CNM) and doxorubicin (DOX). After self-assembly into micelles with the suitable size (∼30 nm), which were termed as TF@CNM + DOX, and upon intravenous administration, the micelles can accumulate in tumor tissues. After FA-mediated endocytosis, the endosomal acidity (∼pH 5) can trigger the release of CNM from TF@CNM + DOX micelles, followed by enhanced accumulation into the mitochondria via the TPP target. This promotes the overproduction of reactive oxygen species (ROS), which can subsequently enhance the intracellular oxidative stress and trigger ROS-responsive release of DOX into the mitochondria. TF@CNM + DOX shows great potential to inhibit the growth of DOX-resistant MCF-7 ADR tumors without observable side effects. Therefore, the tumor and mitochondria dual-targeting polyprodrug design represents an ideal strategy to treat MDR tumors through improvement of the intracellular oxidative level and ROS-responsive drug release.

Mitochondrial dysfunction-targeted nanosystems for precise tumor therapeutics

Mitochondria play critical roles in the regulation of the proliferation and apoptosis of cancerous cells. Targeted induction of mitochondrial dysfunction in cancer cells by multifunctional nanosystems for cancer treatment has attracted increasing attention in the past few years. Numerous therapeutic nanosystems have been designed for precise tumor therapy by inducing mitochondrial dysfunction, including reducing adenosine triphosphate, breaking redox homeostasis, inhibiting glycolysis, regulating proteins, membrane potential depolarization, mtDNA damage, mitophagy dysregulation and so on. Understanding the mechanisms of mitochondrial dysfunction would be helpful for efficient treatment of diseases and accelerating the translation of these therapeutic strategies into the clinic. Then, various strategies to construct mitochondria-targeted nanosystems and induce mitochondrial dysfunction are summarized, and the recent research progress regarding precise tumor therapeutics is highlighted. Finally, the major challenges and an outlook in this rapidly developing field are discussed. This review is expected to inspire further development of novel mitochondrial dysfunction-based strategies for precise treatments of cancer and other human diseases.

A Cationic Amphiphilic AIE Polymer for Mitochondrial Targeting and Imaging

Mitochondria are important organelles that play key roles in generating the energy needed for life and in pathways such as apoptosis. Direct targeting of antitumor drugs, such as doxorubicin (DOX), to mitochondria into cells is an effective approach for cancer therapy and inducing cancer cell death. To achieve targeted and effective delivery of antitumor drugs to tumor cells, to enhance the therapeutic effect, and to reduce the side effects during the treatment, we prepared a cationic amphiphilic polymer with aggregation-induced emission (AIE) characteristic. The polymer could be localized to mitochondria with excellent organelle targeting, and it showed good mitochondrial targeting with low toxicity. The polymer could also self-assemble into doxorubicin-loaded micelles in phosphate buffer, with a particle size of about 4.3 nm, an encapsulation rate of 11.03%, and micelle drug loading that reached 0.49%. The results of in vitro cytotoxicity experiments showed that the optimal dosage was 2.0 μg/mL, which had better inhibitory effect on tumor cells and less biological toxicity on heathy cells. Therefore, the cationic amphiphilic polymer can partially replace expensive commercial mitochondrial targeting reagents, and it can be also used as a drug loading tool to directly target mitochondria in cells for corresponding therapeutic research.

Licorice (Glycyrrhiza glabra L.)-Derived Phytochemicals Target Multiple Signaling Pathways to Confer Oncopreventive and Oncotherapeutic Effects

Cancer is a highly lethal disease, and its incidence has rapidly increased worldwide over the past few decades. Although chemotherapeutics and surgery are widely used in clinical settings, they are often insufficient to provide the cure for cancer patients. Hence, more effective treatment options are highly needed. Although licorice has been used as a medicinal herb since ancient times, the knowledge about molecular mechanisms behind its diverse bioactivities is still rather new. In this review article, different anticancer properties (antiproliferative, antiangiogenic, antimetastatic, antioxidant, and anti-inflammatory effects) of various bioactive constituents of licorice (Glycyrrhiza glabra L.) are thoroughly described. Multiple licorice constituents have been shown to bind to and inhibit the activities of various cellular targets, including B-cell lymphoma 2, cyclin-dependent kinase 2, phosphatidylinositol 3-kinase, c-Jun N-terminal kinases, mammalian target of rapamycin, nuclear factor-κB, signal transducer and activator of transcription 3, vascular endothelial growth factor, and matrix metalloproteinase-3, resulting in reduced carcinogenesis in several in vitro and in vivo models with no evident toxicity. Emerging evidence is bringing forth licorice as an anticancer agent as well as bottlenecks in its potential clinical application. It is expected that overcoming toxicity-related obstacles by using novel nanotechnological methods might importantly facilitate the use of anticancer properties of licorice-derived phytochemicals in the future. Therefore, anticancer studies with licorice components must be continued. Overall, licorice could be a natural alternative to the present medication for eradicating new emergent illnesses while having just minor side effects.

Magnesium Isoglycyrrhizinate Reduces the Target-Binding Amount of Cisplatin to Mitochondrial DNA and Renal Injury through SIRT3

Nephrotoxicity is the dose-limiting factor of cisplatin treatment. Magnesium isoglycyrrhizinate (MgIG) has been reported to ameliorate renal ischemia–reperfusion injury. This study aimed to investigate the protective effect and possible mechanisms of MgIG against cisplatin-induced nephrotoxicity from the perspective of cellular pharmacokinetics. We found that cisplatin predominantly accumulated in mitochondria of renal tubular epithelial cells, and the amount of binding with mitochondrial DNA (mtDNA) was more than twice that with nuclear DNA (nDNA). MgIG significantly lowered the accumulation of cisplatin in mitochondria and, in particular, the degree of target-binding to mtDNA. MgIG notably ameliorated cisplatin-induced changes in mitochondrial membrane potential, morphology, function, and cell viability, while the magnesium donor drugs failed to work. In a mouse model, MgIG significantly alleviated cisplatin-caused renal dysfunction, pathological changes of renal tubules, mitochondrial ultrastructure variations, and disturbed energy metabolism. Both in vitro and in vivo data showed that MgIG recovered the reduction of NAD+-related substances and NAD+-dependent deacetylase sirtuin-3 (SIRT3) level caused by cisplatin. Furthermore, SIRT3 knockdown weakened the protective effect of MgIG on mitochondria, while SIRT3 agonist protected HK-2 cells from cisplatin and specifically reduced platinum-binding activity with mtDNA. In conclusion, MgIG reduces the target-binding amount of platinum to mtDNA and exerts a protective effect on cisplatin-induced renal injury through SIRT3, which may provide a new strategy for the treatment of cisplatin-induced nephrotoxicity.

Cellular and subcellular interactions of graphene-based materials with cancerous and non-cancerous cells

Despite significant advances in early detection and personalized treatment, cancer is still among the leading causes of death globally. One of the possible anticancer approaches that is presently receiving a lot of attention is the development of nanocarriers capable of specific and efficient delivery of anticancer drugs. Graphene-based materials are promising nanocarriers in this respect, due to their high drug loading capacity and biocompatibility. In this review, we present an overview on the interactions of graphene-based materials with normal mammalian cells at the molecular level as well as cellular and subcellular levels, including plasma membrane, cytoskeleton, and membrane-bound organelles such as lysosomes, mitochondria, nucleus, endoplasmic reticulum, and peroxisome. In parallel, we assemble the knowledge about the interactions of graphene-based materials with cancerous cells, that are considered as the potential applications of these materials for cancer therapy including metastasis treatment, targeted drug delivery, and differentiation to non-cancer stem cells. We highlight the influence of key parameters, such as the size and surface chemistry of graphene-based materials that govern the efficiency of internalization and biocompatibility of these particles in vitro and in vivo. Finally, this review aims to correlate the key parameters of graphene-based nanomaterials specially graphene oxide, such as size and surface modifications, to their interactions with the cancerous and non-cancerous cells for designing and engineering them for bio-applications and especially for therapeutic purposes.

A nano-preparation approach to enable the delivery of daphnoretin to potentiate the therapeutical efficacy in hepatocellular cancer

Daphnoretin (DAP), isolated from a traditional Chinese medicine Wikstroemia indica (Linn. C. A. Meyer), could induce apoptosis of hepatocellular cancer (HCC) and inhibit tumor growth. However, the application of DAP in cancer therapies was hampered because to its poor solubility. Herein, this study aimed to design an approach of double-targeted nano-preparation to enable the delivery of DAP to potentiate the therapeutical efficacy in liver cancer via glycyrrhetinic acid-polyethylene glycol-block-poly (D,L-lactic acid)/polyethylene glycol-block-poly (D,L-lactic acid)-DAP (GPP/PP-DAP). In particular, the purity of separated DAP was up to 98.12% for preparation research. GPP/PP-DAP was successfully prepared by the thin-film hydration method. Subsequently, the GPP/PP-DAP was optimized by univariate analysis and the response surface methodology, producing a stable and systemically injectable nano-preparation. Impressively, on the one hand, cytotoxicity studies showed that the IC₅₀ of the GPP/PP-DAP was lower than that of free DAP. On the other hand, the GPP/PP-DAP was more likely to be endocytosed by HepG2 cells and targeted to the liver with orthotopic tumors, potentiating the therapeutical efficacy in HCC. Collectively, both in vitro and in vivo results indicated the excellent tumor inhibition and liver targeting of GPP/PP-DAP, suggesting the nano-preparation could serve as a potential drug delivery system for natural ingredients with anti-hepatoma activity to lay the theoretical foundation for clinical application.

Precision Nanomedicines: Targeting Hot Mitochondria in Cancer Cells

Mitochondrion is a multifunctional organelle in a cell, and it is one of the important targets of antitumor therapy. Conventional mitochondrial targeting strategies can hardly distinguish the mitochondria in cancer cells from those in normal cells, which might raise a concern about the biosafety. Recent studies suggest that a relatively high temperature of mitochondria exists in cancer cells. We named it tumor intrinsic mitochondrial overheating (TIMO). By taking advantage of the difference in mitochondrial temperatures between cancer cells and normal cells, therapeutic agents can be specifically delivered to the mitochondria in cancer cells. Here we will briefly overview the mitochondria-targeted delivery strategies. In addition, the recent discovery of hot mitochondria in cancer cells and the development of mitochondrial temperature-responsive delivery systems for antitumor therapy will be reviewed.

Multifunctional graphene oxide nanoparticles for drug delivery in cancer

Recent advancements in nanotechnology have enabled us to develop sophisticated multifunctional nanoparticles or nanosystems for targeted diagnosis and treatment of several illnesses, including cancers. To effectively treat any solid tumor, the therapy should preferably target just the malignant cells/tissue with minor damage to normal cells/tissues. Graphene oxide (GO) nanoparticles have gained considerable interest owing to their two-dimensional planar structure, chemical/mechanical stability, excellent photosensitivity, superb conductivity, high surface area, and good biocompatibility in cancer therapy. Many compounds have been functionalized on the surface of GO to increase their biological applications and minimize cytotoxicity. The review presents an overview of the physicochemical characteristics, strategies for various modifications, toxicity and biocompatibility of graphene and graphene oxide, current trends in developing GO-based nano constructs as a drug delivery cargo and other biological applications, including chemo-photothermal therapy, chemo-photodynamic therapy, bioimaging, and theragnosis in cancer. Further, the review discusses the challenges and opportunities of GO, GO-based nanomaterials for the said applications. Overall, the review focuses on the therapeutic potential of strategically developed GO nanomedicines and comprehensively discusses their opportunities and challenges in cancer therapy.

Biofunctionalized graphene oxide nanosheet for amplifying antitumor therapy: Multimodal high drug encapsulation, prolonged hyperthermal window, and deep-site burst drug release

Biofunctional surface-modification surpassed critical limitation of graphene oxide (GO) in biocompatibility and drug delivery efficiency, contributing to versatile biomedical applications. Here, a protein corona-bridged GO nanoplatform with high drug loading, longstanding hyperthermia, and controllable drug release, was engineered for amplified tumor therapeutic benefits. Structurally, GO surface was installed with phenylboronic acid (PBA) layer, on which iRGD conjugated apolipoprotein A-I (iRGD-apoA-I) was coordinated via boron electron-deficiency, to form the sandwich-like GO nanosheet (iAPG). The GO camouflaging by iRGD-apoA-I corona provided multimodal high doxorubicin (DOX) loading by π-π stacking and coordination, and generated a higher photothermal transformation efficiency simultaneously. In vitro studies demonstrated that iAPG significantly improved drug penetration and internalization, then achieved tumor-targeted DOX release through near-infrared (NIR) controlled endo/lysosome disruption. Moreover, iAPG mediated site-specific drug shuttling to produce a 3.53-fold enhancement of tumor drug-accumulation compared to the free DOX in vivo, and induced deep tumor penetration dramatically. Primary tumor ablation and spontaneous metastasis inhibition were further demonstrated with negligible side effects under optimal NIR. Taken together, our work provided multifunctional protein corona strategy to inorganic nanomaterials toward advantageous biomedical applications.

Glycyrrhetinic acid restricts mitochondrial energy metabolism by targeting SHMT2

Glycyrrhetinic acid (GA) is a natural product of licorice with mitochondria targeting properties and shows broad anticancer activities, but its targets and underlying mechanisms remain elusive. Here, we identified the mitochondrial enzyme serine hydroxymethyltransferase 2 (SHMT2) as a target of GA by using chemical proteomics. Binding to and inhibiting the activity of SHMT2 by GA were validated in vitro and in vivo. Knockout of SHMT2 or inhibiting SHMT2 with GA restricts mitochondrial energy supplies by downregulating mitochondrial oxidative phosphorylation (OXPHOS) and fatty acid β-oxidation, and consequently suppresses cancer cell proliferation and tumor growth. Crystal structures of GA derivatives indicate that GA occupies SHMT2 folate-binding pocket and regulates SHMT2 activity. Modifications at GA carboxylic group with diamines significantly improved its anticancer potency, demonstrating GA as a decent structural template for SHMT2 inhibitor development.

Emerging trends in nano-bioactive-mediated mitochondria-targeted therapeutic stratagems using polysaccharides, proteins and lipidic carriers

The emergence of new lifestyle disorders and pharmaco-resistant variants of diseases has necessitated the search for effective therapeutic moieties and approaches that could overcome the limitations in the existing treatment modalities. In this context, bioactives such as flavonoids, polyphenols, tannins, terpenoids and alkaloids have demonstrated promise in therapy owing to their ability to scavenge free radicals and modulate the mitochondrial function as well as regulate metabolic pathways. However, their clinical applicability is low owing to their poor bioavailability and aqueous solubility. The encapsulation of bioactives in nanodimensional particles has overcome these limitations to a large extent while simultaneously conferring additional advantages of improved circulation time, enhanced cell uptake and target specific release. A wide range of nanocarriers derived from biopolymers such as polysaccharides, lipids and proteins, have been explored for encapsulation of different bioactives and have reported significant improvement of the bioavailability and therapeutic efficacy of the encapsulated cargo. However, incorporation of cell-specific and mitochondria-specific elements on the nanocarriers has been relatively less explored. This review summarizes some of the recent attempts to treat different disorders using bioactives encapsulated in biopolymer nanostructures and few instances of mitochondria-specific delivery.

Recent Advances in Glycyrrhetinic Acid-Functionalized Biomaterials for Liver Cancer-Targeting Therapy

Liver cancer is one of the most common causes of cancer mortality worldwide. Chemotherapy and radiotherapy are the conventional therapies generally employed in patients with liver tumors. The major issue associated with the administration of chemotherapeutics is their high toxicity and lack of selectivity, leading to systemic toxicity that can be detrimental to the patient's quality of life. An important approach to the development of original liver-targeted therapeutic products takes advantage of the employment of biologically active ligands able to bind specific receptors on the cytoplasmatic membranes of liver cells. In this perspective, glycyrrhetinic acid (GA), a pentacyclic triterpenoid present in roots and rhizomes of licorice, has been used as a ligand for targeting the liver due to the expression of GA receptors on the sinusoidal surface of mammalian hepatocytes, so it may be employed to modify drug delivery systems (DDSs) and obtain better liver or hepatocyte drug uptake and efficacy. In the current review, we focus on the most recent and interesting research advances in the development of GA-based hybrid compounds and DDSs developed for potential employment as efficacious therapeutic options for the treatment of hepatic cancer.

Sequential Drug Delivery in Targeted Cancer Therapy

Cancer is a major public health problem and one of the leading causes of death. However, traditional cancer therapy may damage normal cells and cause side effects. Many targeted drug delivery platforms have been developed to overcome the limitations of the free form of therapeutics and biological barriers. The commonly used cancer cell surface targets are CD44, matrix metalloproteinase-2, folate receptors, etc. Once the drug enters the cell, active delivery of the drug molecule to its final destination is still preferred. The subcellular targeting strategies include using glucocorticoid receptors for nuclear targeting, negative mitochondrial membrane potential and N-acetylgalactosaminyltransferase for Golgi apparatus targeting, etc. Therefore, the most effective way to deliver therapeutic agents is through a sequential drug delivery system that simultaneously achieves cellular- and subcellular-level targeting. The dual-targeting delivery holds great promise for improving therapeutic effects and overcoming drug resistance. This review classifies sequential drug delivery systems based on final targeted organelles. We summarize different targeting strategies and mechanisms and gave examples of each case.

Recent Advancements in Mitochondria-Targeted Nanoparticle Drug Delivery for Cancer Therapy

Mitochondria are critical subcellular organelles that produce most of the adenosine triphosphate (ATP) as the energy source for most eukaryotic cells. Moreover, recent findings show that mitochondria are not only the "powerhouse" inside cells, but also excellent targets for inducing cell death via apoptosis that is mitochondria-centered. For several decades, cancer nanotherapeutics have been designed to specifically target mitochondria with several targeting moieties, and cause mitochondrial dysfunction via photodynamic, photothermal, or/and chemo therapies. These strategies have been shown to augment the killing of cancer cells in a tumor while reducing damage to its surrounding healthy tissues. Furthermore, mitochondria-targeting nanotechnologies have been demonstrated to be highly efficacious compared to non-mitochondria-targeting platforms both in vitro and in vivo for cancer therapies. Moreover, mitochondria-targeting nanotechnologies have been intelligently designed and tailored to the hypoxic and slightly acidic tumor microenvironment for improved cancer therapies. Collectively, mitochondria-targeting may be a promising strategy for the engineering of nanoparticles for drug delivery to combat cancer.

Curcumin and Graphene Oxide Incorporated into Alginate Hydrogels as Versatile Devices for the Local Treatment of Squamous Cell Carcinoma

With the aim of preparing hybrid hydrogels suitable for use as patches for the local treatment of squamous cell carcinoma (SCC)-affected areas, curcumin (CUR) was loaded onto graphene oxide (GO) nanosheets, which were then blended into an alginate hydrogel that was crosslinked by means of calcium ions. The homogeneous incorporation of GO within the polymer network, which was confirmed through morphological investigations, improved the stability of the hybrid system compared to blank hydrogels. The weight loss in the 100-170 °C temperature range was reduced from 30% to 20%, and the degradation of alginate chains shifted to higher temperatures. Moreover, GO enhanced the stability in water media by counteracting the de-crosslinking process of the polymer network. Cell viability assays showed that the loading of CUR (2.5% and 5% by weight) was able to reduce the intrinsic toxicity of GO towards healthy cells, while higher amounts were ineffective due to the antioxidant/prooxidant paradox. Interestingly, the CUR-loaded systems were found to possess a strong cytotoxic effect in SCC cancer cells, and the sustained CUR release (~50% after 96 h) allowed long-term anticancer efficiency to be hypothesized.

Doxorubicin-loaded graphene oxide nanocomposites in cancer medicine: Stimuli-responsive carriers, co-delivery and suppressing resistance

INTRODUCTION

The application of doxorubicin (DOX) in cancer therapy has been limited due to its drug resistance and poor internalization. Graphene oxide (GO) nanostructures have the capacity for DOX delivery while promoting its cytotoxicity in cancer.

AREAS COVERED

The favorable characteristics of GO nanocomposites, preparation method, and application in cancer therapy are described. Then, DOX resistance in cancer is discussed. The GO-mediated photothermal therapy and DOX delivery for cancer suppression are described. Preparation of stimuli-responsive GO nanocomposites, surface functionalization, hybrid nanoparticles, and theranostic applications are emphasized in DOX chemotherapy.

EXPERT OPINION

Graphene oxide nanoparticle-based photothermal therapy maximizes the anti-cancer activity of DOX against cancer cells. Apart from DOX delivery, GO nanomaterials are capable of loading anti-cancer agents and genetic tools to minimize drug resistance and enhance the cytolytic impact of DOX in cancer eradication. To enhance DOX accumulation in cancer cells, stimuli-responsive (redox-, light-, enzyme- and pH-sensitive) GO nanoparticles have been developed for DOX delivery. Further development of targeted delivery of DOX-loaded GO nanomaterials against cancer cells may be achieved by surface modification of polymers such as polyethylene glycol, hyaluronic acid, and chitosan. Doxorubicin-loaded GO nanoparticles have demonstrated theranostic potential for simultaneous diagnosis and therapy. Hybridization of GO with other nanocarriers such as silica and gold nanoparticles further broadens their potential anti-cancer therapy applications.

Engineering of Small Molecular Organic Nanoparticles for Mitochondria-Targeted Mild Photothermal Therapy of Malignant Breast Cancers

Conventional photothermal therapy (PTT) often causes unwanted hyperthermia damage to surrounding healthy tissues, and as well fails in ablation of infiltrating and malignant tumors, which even leads to tumor recurrence....

Mito-Bomb: Targeting Mitochondria for Cancer Therapy

Cancer has been one of the most common life-threatening diseases for a long time. Traditional cancer therapies such as surgery, chemotherapy (CT), and radiotherapy (RT) have limited effects due to drug resistance, unsatisfactory treatment efficiency, and side effects. In recent years, photodynamic therapy (PDT), photothermal therapy (PTT), and chemodynamic therapy (CDT) have been utilized for cancer treatment owing to their high selectivity, minor resistance, and minimal toxicity. Accumulating evidence has demonstrated that selective delivery of drugs to specific subcellular organelles can significantly enhance the efficiency of cancer therapy. Mitochondria-targeting therapeutic strategies are promising for cancer therapy, which is attributed to the essential role of mitochondria in the regulation of cancer cell apoptosis, metabolism, and more vulnerable to hyperthermia and oxidative damage. Herein, the rational design, functionalization, and applications of diverse mitochondria-targeting units, involving organic phosphine/sulfur salts, quaternary ammonium (QA) salts, peptides, transition-metal complexes, guanidinium or bisguanidinium, as well as mitochondria-targeting cancer therapies including PDT, PTT, CDT, and others are summarized. This review aims to furnish researchers with deep insights and hints in the design and applications of novel mitochondria-targeting agents for cancer therapy.

Mitochondria-targeted graphene for advanced cancer therapeutics

There have been numerous efforts to develop targeted therapies for treating cancer. The non-specificity of 'classical' cytotoxic chemotherapy drugs and drug resistance remain major challenges in cancer dormancy. Mitochondria-targeted therapy is an alternative strategy for the treatment of numerous cancer types and is heavily dependent on the ability of the anticancer drugs to reach the tumor mitochondria in a safe and selective manner. Over the past two decades, research efforts have provided mechanistic insights into the roles of mitochondria in cancer progression and therapies that specifically target cancer mitochondria. Given that several nanotechnology-driven strategies aimed at therapeutically targeting mitochondrial dysfunction are still in their infancy, this review considers the cross-disciplinary nature of this area and focuses on the design and development of mitochondria-targeted graphene (mitoGRAPH), its immense potential, and future use for selective targeting of cancer mitochondria. This review also provides novel insights into the strategies for preparing mitoGRAPH to destroy the cell powerhouse in a targeted fashion. Targeting mitochondria with graphene may represent an important therapeutic approach that transforms therapeutic interventions. STATEMENT OF SIGNIFICANCE: Mitochondria-targeted therapy represents a major advance for treating several medical conditions. At this time, no nanoparticles (NPs) or nanocarriers are clinically available, which are capable of spatial targeting and controlled delivery of drugs to mitochondria. NPs-based approaches have revolutionized the field of targeted therapy and have demonstrated efficacy for delivering drugs selectively to mitochondria. These NPs show limited results in pre-clinical animal models due to their adverse side effects and inadequate therapeutic outcomes. Over the past decade, graphene has emerged as a potential anticancer agent and has shown great potential in targeting tumor mitochondria in a safe and targeted fashion. This review considers recent advances in the use of mitochondria-targeted graphene (mitoGRAPH) in chemotherapy, photodynamic therapy, photothermal therapy, and combination therapies.

Endogenous reactive oxygen species burst induced and spatiotemporally controlled multiple drug release by traceable nanoparticles for enhancing antitumor efficacy

Reactive oxygen species (ROS) are not only used as a therapeutic reagent in chemodynamic therapy (CDT), to stimulate the release of antineoplastic drugs, they can also be used to achieve a combined effect of CDT and chemotherapy to enhance anticancer effects. Herein, we synthesized a pH-responsive prodrug (PEG2k-NH-N-DOX), ROS-responsive prodrug (PEG2k-S-S-CPT-ROS), organic CDT agents (TPP-PEG2k-LND, TPP-PEG2k-TOS), and T1-enhanced magnetic resonance imaging contrast agents (Gd-DTPA-N16-16), and used them to encapsulate combrestatinA4 (CA4) to prepare traceable pH/ROS dual-responsive multifunctional nanoparticles (TLDCAG NPs) with endogenous ROS burst and spatiotemporally controlled multiple drug release ability. Firstly, TLDCAG NPs were accumulated in the tumor cell microenvironment via an enhanced permeability and retention (EPR) effect. Secondly, CA4 was released and specifically destroyed angiogenesis to facilitate the interaction between the tumor and the remaining TLDCG NPs. After accumulating in tumor cells, the TLDCG NPs could be destroyed under acidic conditions to quickly release doxorubicin (DOX), TPP-PEG2k-LND, and TPP-PEG2k-TOS. Thirdly, TPP-PEG2k-LND and TPP-PEG2k-TOS quickly targeted mitochondria, induced endogenous ROS bursts, reduced the mitochondrial membrane potential, and induced tumor cell apoptosis. Endogenous ROS can not only be used as a therapeutic reagent for CDT, but also can cut off the thioketal bond in PEG2k-S-S-CPT-ROS and release camptothecin (CPT). Finally, TLDCAG NPs were traced by magnetic resonance imaging (MRI). Furthermore, in vitro and vivo results indicate that the TLDCAG NPs have vigorous antitumor activity and negligible systemic toxicity. Therefore, the TLDCAG NPs provide an efficient strategy for enhancing antitumor efficacy.

Recent progress of graphene oxide-based multifunctional nanomaterials for cancer treatment

Background

In the last decade, graphene oxide-based nanomaterials, such as graphene oxide (GO) and reduced graphene oxide (rGO), have attracted more and more attention in the field of biomedicine. Due to the versatile surface functionalization, ultra-high surface area, and excellent biocompatibility of graphene oxide-based nanomaterials, which hold better promise for potential applications than among other nanomaterials in biomedical fields including drug/gene delivery, biomolecules detection, tissue engineering, especially in cancer treatment.

Results

Here, we review the recent progress of graphene oxide-based multifunctional nanomaterials for cancer treatment. A comprehensive and in-depth depiction of unique property of graphene oxide-based multifunctional nanomaterials is first interpreted, with particular descriptions about the suitability for applying in cancer therapy. Afterward, recently emerging representative applications of graphene oxide-based multifunctional nanomaterials in antitumor therapy, including as an ideal carrier for drugs/genes, phototherapy, and bioimaging, are systematically summarized. Then, the biosafety of the graphene oxide-based multifunctional nanomaterials is reviewed.

Conclusions

Finally, the conclusions and perspectives on further advancing the graphene oxide-based multifunctional nanomaterials toward potential and versatile development for fundamental researches and nanomedicine are proposed.

Graphic abstract

An understanding of mitochondria and its role in targeting nanocarriers for diagnosis and treatment of cancer

Nanotechnology has changed the entire paradigm of drug targeting and has shown tremendous potential in the area of cancer therapy due to its specificity. In cancer, several targets have been explored which could be utilized for the better treatment of disease. Mitochondria, the so-called powerhouse of cell, portrays significant role in the survival and death of cells, and has emerged as potential target for cancer therapy. Direct targeting and nanotechnology based approaches can be tailor-made to target mitochondria and thus improve the survival rate of patients suffering from cancer. With this backdrop, in present review, we have reemphasized the role of mitochondria in cancer progression and inhibition, highlighting the different targets that can be explored for targeting of disease. Moreover, we have also summarized different nanoparticulate systems that have been used for treatment of cancer via mitochondrial targeting.

Nanotherapeutic approaches to target mitochondria in cancer

Treatment of cancer cells exemplifies a difficult test in the light of challenges associated with the nature of cancer cells and the severe side effects too. After making a large number of trials using both traditional and advanced therapies (immunotherapy and hormone therapy), approaches to design new therapies have reached a saturation level. However, nanotechnology-based approaches exhibit higher efficacy and great potential to bypass many of such therapeutic limitations. Because of their higher target specificity, the use of nanoparticles offers incredible potential in cancer therapeutics. Mitochondria, acting as a factory of energy production in cells, reveal an important role in the death as well as the survival of cells. Because of its significant involvement in the proliferation of cancer cells, it is being regarded as an important target for cancer therapeutics. Numerous studies reveal that nanotechnology-based approaches to directly target the mitochondria may help in improving the survival rate of cancer patients. In the current study, we have detailed the significance of mitochondria in the development of cancer phenotype, as well as indicated it as the potential targets for cancer therapy. Our study further highlights the importance of different nanoparticle-based approaches to target mitochondria of cancer cells and the associated outcomes of different studies. Though, nanotechnology-based approaches to target mitochondria of cancer cells demonstrate a potential and efficient way in cancer therapeutics. Yet, further study is needed to overcome the linked limitations.

Novel Strategies for Disrupting Cancer-Cell Functions with Mitochondria-Targeted Antitumor Drug-Loaded Nanoformulations

Any variation in normal cellular function results in mitochondrial dysregulation that occurs in several diseases, including cancer. Such processes as oxidative stress, metabolism, signaling, and biogenesis play significant roles in cancer initiation and progression. Due to their central role in cellular metabolism, mitochondria are favorable therapeutic targets for the prevention and treatment of conditions like neurodegenerative diseases, diabetes, and cancer. Subcellular mitochondria-specific theranostic nanoformulations for simultaneous targeting, drug delivery, and imaging of these organelles are of immense interest in cancer therapy. It is a challenging task to cross multiple barriers to target mitochondria in diseased cells. To overcome these multiple barriers, several mitochondriotropic nanoformulations have been engineered for the transportation of mitochondria-specific drugs. These nanoformulations include liposomes, dendrimers, carbon nanotubes, polymeric nanoparticles (NPs), and inorganic NPs. These nanoformulations are made mitochondriotropic by conjugating them with moieties like dequalinium, Mito-Porter, triphenylphosphonium, and Mitochondria-penetrating peptides. Most of these nanoformulations are meticulously tailored to control their size, charge, shape, mitochondriotropic drug loading, and specific cell-membrane interactions. Recently, some novel mitochondria-selective antitumor compounds known as mitocans have shown high toxicity against cancer cells. These selective compounds form vicious oxidative stress and reactive oxygen species cycles within cancer cells and ultimately push them to cell death. Nanoformulations approved by the FDA and EMA for clinical applications in cancer patients include Doxil, NK105, and Abraxane. The novel use of these NPs still faces tremendous challenges and an immense amount of research is needed to understand the proper mechanisms of cancer progression and control by these NPs. Here in this review, we summarize current advancements and novel strategies of delivering different anticancer therapeutic agents to mitochondria with the help of various nanoformulations.

Mitochondria and Endoplastic Reticulum Targeting Strategy for Enhanced Phototherapy

To ensure improved efficacy and minimized toxicity of therapeutic molecules, it is generally accepted that specifically delivering them to the subcellular site of their action will be attractive. Phototherapy has received considerable attention because of its noninvasiveness, high temporal-spatial resolution, and minimal drug resistance. As important functional organelles in cells, mitochondria and endoplasmic reticulum (ER) participate in fundamental cellular processes, which make them much more sensitive to reactive oxygen species (ROS) and hyperthermia. Thus, mitochondria- or ER-targeted phototherapy will be rational strategies for synergetic cancer therapy. In this review, we focus on the latest advances in molecules and nanomaterials currently used for mitochondria- and ER-targeted phototherapy.

Drug Delivery With Carbon-Based Nanomaterials as Versatile Nanocarriers: Progress and Prospects

With growing interest, a large number of researches have been conducted on carbon-based nanomaterials (CBNs). However, their uses are limited due to comprehensive potential environmental and human health effects. It is often confusing for researchers to make an informed choice regarding the versatile carbon-based nanocarrier system and its potential applications. This review has highlighted emerging applications and cutting-edge progress of CBNs in drug delivery. Some critical factors like enzymatic degradation, surface modification, biological interactions, and bio-corona have been discussed here. These factors will help to fabricate CBNs for effective drug delivery. This review also addresses recent advancements in carbon-based target specific and release controlled drug delivery to improve disease treatment. The scientific community has turned their research efforts into the development of novel production methods of CBNs to make their production more attractive to the industrial sector. Due to the nanosize and diversified physical properties, these CBNs have demonstrated distinct biological interaction. Thus long-term preclinical toxicity study is recommended before finally translating to clinical application.

Near-Infrared Photo-controlled Permeability of a Biomimetic Polymersome with Sustained Drug Release and Efficient Tumor Therapy

Synthetic polymersomes have structure similarity to bio-vesicles and could disassemble in response to stimuli for "on-demand" release of encapsulated cargos. Though widely applied as a drug delivery carrier, the burst release mode with structure complete destruction is usually taken for most responsive polymersomes, which would shorten the effective drug reaction time and impair the therapeutic effect. Inspired by the cell organelles' communication mode via regulating membrane permeability for transportation control, we highlight here a biomimetic polymersome with sustained drug release over a specific period of time via near-infrared (NIR) pre-activation. The polymersome is prepared by the self-assembling amphiphilic diblock copolymer P(OEGMA-co-EoS)-b-PNBOC and encapsulates the hypoxia-activated prodrug AQ4N and upconversion nanoparticle (PEG-UCNP) in its hydrophilic centric cavity. Thirty minutes of NIR pre-activation triggers cross-linking of NBOC and converts the permeability of the polymersome with sustained AQ4N release until 24 h after the NIR pre-activation. The photosensitizer EoS is activated and aggravates environmental hypoxic conditions during a sustained drug release period to boost the AQ4N therapeutic effect. The combination of sustained drug release with concurrent hypoxia intensification results in a highly efficient tumor therapeutic effect both intracellularly and in vivo. This biomimetic polymersome will provide an effective and universal tumor therapeutic approach.

Gelatin reduced Graphene Oxide Nanosheets as Kartogenin Nanocarrier Induces Rat ADSCs Chondrogenic Differentiation Combining with Autophagy Modification

Biocompatible reduced graphene oxide (rGO) could deliver drugs for synergistically stimulating stem cells directed differentiation with influences on specific cellular activities. Here, we prepared a biodegradable gelatin reduced graphene oxide (rGO@Ge) to evaluate its functions in promoting rat adipose derived mesenchymal stem cells (ADSCs) chondrogenic differentiation through delivering kartogenin (KGN) into the stem cell efficiently. The optimum KGN concentration (approximately 1 μM) that promoted the proliferation and chondrogenic differentiation of ADSCs was clarified by a series of experiments, including immunofluorescent (IF) staining (Sox-9, Col II), alcian blue (Ab) staining, toluidine blue (Tb) staining and real-time quantitative PCR analysis of the chondrogenic markers. Meanwhile, the biocompatibility of rGO@Ge was evaluated to clearly define the nonhazardous concentration range, and the drug loading and releasing properties of rGO@Ge were tested with KGN for its further application in inducing ADSCs chondrogenic differentiation. Furthermore, the mechanism of rGO@Ge entering ADSCs was investigated by the different inhibitors that are involved in the endocytosis of the nanocarrier, and the degradation of the rGO@Ge in ADSCs was observed by transmission electron microscopy (TEM). The synergistic promoting effect of rGO@Ge nanocarrier on ADSCs chondrogenesis with KGN was also studied by the IF, Ab, Tb stainings and PCR analysis of the chondrogenic markers. Finally, the intracellular Reactive Oxygen Species (ROS) and autophagy induced by KGN/rGO@Ge complex composites were tested in details for clarification on the correlation between the autophagy and chondrogenesis in ADSCs induced by rGO@Ge. All the results show that rGO@Ge as a biocompatible nanocarrier can deliver KGN into ADSCs for exerting a pro-chondrogenic effect and assist the drug to promote ADSCs chondrogenesis synergistically through modification of the autophagy in vitro, which promised its further application in repairing cartilage defect in vivo.

Targeting the Opening of Mitochondrial Permeability Transition Pores Potentiates Nanoparticle Drug Delivery and Mitigates Cancer Metastasis

Mitochondria are highly involved in the metastasis of cancer cells. However, low permeability of mitochondria impedes the entry of anti-cancer drugs. Here, a self-assembled nanoparticle platform is designed that not only targets the DNA-intercalating agent doxorubicin to mitochondria but also enhances the specific penetration by opening the mitochondrial permeability transition pores (MPTPs). With drastic improvement in mitochondrial uptake, the drug delivery system results in substantial mitochondrial impairment leading to amplified induction of apoptosis, depletion of energy supply, and inhibition of numerous metastasis-associated proteins. As a consequence, the drug delivery system significantly inhibits the orthotopic tumor growth, and suppressed the metastasis of cancer cells detached from primary tumors. Additionally, the nanoparticle exhibits a potent effect on eradicating the metastasis of disseminated tumor cell from blood to lung. The results show that strategies of targeting mitochondria and unlocking MPTP are feasible and beneficial to mitigate both tumorigenesis and metastasis.

A directed co-assembly of herbal small molecules into carrier-free nanodrugs for enhanced synergistic antitumor efficacy

Carrier-free nanomedicines without structural modification are attractive for the development of natural small molecules (NSMs) and biomedical applications. Moreover, the combination of NSMs is expected to obtain nanomedicines with high efficacy and low side effects due to their inherent pharmacological activities and health benefits. However, poor water solubility and low bioavailability of NSMs limit their wider biomedical and clinical applications. In this study, we revealed the co-assembly properties of pentacyclic triterpenoids and constructed a series of carrier-free nanodrugs, which are co-assembled nanoparticles (NPs) formed by the combination of two NSMs via a supramolecular assembly strategy. Experimental work and simulation studies were combined to reveal the co-assembly mechanism of non-covalent interactions between NSMs. Not only do co-assembled NPs have rapid cellular uptake ability and passive targeting tumor ability based on the EPR effect, but also their constituent units could arrest the cell cycle at different stages of tumor cells and induce apoptosis, showing synergistic anti-tumor effects (CI < 0.7). Compared with self-assembled NPs and positive control, co-assembled NPs show the strongest therapeutic effect in vivo. Importantly, the co-assembled NPs highlight the unique advantages of NSMs in terms of biosafety and health benefits, and systemic toxicity and histological examination confirm that co-assembled NPs have reliable biosafety, and no side effects and nano toxicity risks were observed.

Recent advances in graphene-family nanomaterials for effective drug delivery and phototherapy

INTRODUCTION

Owing to the unique properties of graphene, including large specific surface area, excellent thermal conductivity, and optical absorption, graphene-family nanomaterials (GFNs) have attracted extensive attention in biomedical applications, particularly in drug delivery and phototherapy.

AREAS COVERED

In this review, we point out several challenges involved in the clinical application of GFNs. Then, we provide an overview of the most recent publications about GFNs in biomedical applications, including diverse strategies for improving the biocompatibility, specific targeting and stimuli-responsiveness of GFNs for drug delivery, codelivery of drug and gene, photothermal therapy, photodynamic therapy, and multimodal combination therapy.

EXPERT OPINION

Although the application of GFNs is still in the preclinical stage, rational modification of GFNs with functional elements or making full use of GFNs-based multimodal combination therapy might show great potential in biomedicine for clinical application.

Glycyrrhetinic Acid-Modified Silicon Phthalocyanine for Liver Cancer-Targeted Photodynamic Therapy

To supplement shortcomings of existing treatments and enhance the therapeutic effect for liver cancer, a novel photosensitizer is designed using silicon phthalocyanine (SiPC) and a unique targeting moiety, glycyrrhetinic acid (GA). The SiPC is modified with a hydrophilic polymer and finally bound with GA. The solubility, fluorescence, singlet oxygen generation, and UV-vis absorbance are analyzed, and receptor-dependent intracellular influx is estimated in various cell lines. Using flow cytometry and confocal microscopy, intracellular fluorescence was detected in liver cancer because of GA receptor overexpression. To prove in vitro photodynamic therapeutic effects, the sample treated cells are irradiated and viability of liver cancer cells decreases in proportion to laser power. Then, it is confirmed that GA-modified SiPC effectively accumulated in liver cancer of HepG2 tumor-bearing mouse. Additionally, the PDT-combined therapeutic effect of GA-modified SiPC is observed in the tumor model and shown to have a tumor growth inhibition effect (60.36 times higher than the control group) and supported by histological analyses. These results demonstrate that the newly modified SiPC can be applied to liver cancer-specific treatment with high therapeutic efficacy. Consequently, novel SiPC has the potential to alter conventional liver cancer-targeted therapy and chemotherapy in clinical use.

Sublethal exposure of small few-layer graphene promotes metabolic alterations in human skin cells

Small few-layer graphene (sFLG), a novel small-sized graphene-related material (GRM), can be considered as an intermediate degradation product of graphene. GRMs have a promising present and future in the field of biomedicine. However, safety issues must be carefully addressed to facilitate their implementation. In the work described here, the effect of sub-lethal doses of sFLG on the biology of human HaCaT keratinocytes was examined. A one-week treatment of HaCaTs with sub-lethal doses of sFLG resulted in metabolome remodeling, dampening of the mitochondrial function and a shift in the redox state to pro-oxidant conditions. sFLG raises reactive oxygen species and calcium from 24 h to one week after the treatment and this involves the activation of NADPH oxidase 1. Likewise, sFLG seems to induce a shift from oxidative phosphorylation to glycolysis and promotes the use of glutamine as an alternative source of energy. When sub-toxic sFLG exposure was sustained for 30 days, an increase in cell proliferation and mitochondrial damage were observed. Further research is required to unveil the safety of GRMs and degradation-derived products before their use in the workplace and in practical applications.

Mitocans Revisited: Mitochondrial Targeting as Efficient Anti-Cancer Therapy

Mitochondria are essential cellular organelles, controlling multiple signalling pathways critical for cell survival and cell death. Increasing evidence suggests that mitochondrial metabolism and functions are indispensable in tumorigenesis and cancer progression, rendering mitochondria and mitochondrial functions as plausible targets for anti-cancer therapeutics. In this review, we summarised the major strategies of selective targeting of mitochondria and their functions to combat cancer, including targeting mitochondrial metabolism, the electron transport chain and tricarboxylic acid cycle, mitochondrial redox signalling pathways, and ROS homeostasis. We highlight that delivering anti-cancer drugs into mitochondria exhibits enormous potential for future cancer therapeutic strategies, with a great advantage of potentially overcoming drug resistance. Mitocans, exemplified by mitochondrially targeted vitamin E succinate and tamoxifen (MitoTam), selectively target cancer cell mitochondria and efficiently kill multiple types of cancer cells by disrupting mitochondrial function, with MitoTam currently undergoing a clinical trial.

Preparation, evaluation, and in vitro cytotoxicity studies of artesunate-loaded glycyrrhetinic acid decorated PEG-PLGA nanoparticles

OBJECTIVE

The objective of this study was to prepare the liver targeting drug delivery system (TDDS) of artesunate (ART)-loaded polyethylene glycol (PEG)-poly(d,l-lactic-co-glycolic) acid (PLGA) nanoparticles (NPs) modified by glycyrrhetinic acid (GA), and evaluate its in vitro cytotoxicity.

SIGNIFICANCE

The GA-PEG-PLGA-ART NPs enhanced the in vitro cytotoxicity on HCC cell lines. The development of GA-PEG-PLGA NPs will greatly push the clinical applications of ART as a novel anticancer drug.

METHODS

The NPs were prepared using solvent evaporation method, and the formulation was optimized through an orthogonal design. In addition, physical properties were determined, including particle size, polydispersity index (PDI), zeta potential (ZP), morphology, drug loading capacity (LC) and encapsulation efficiency (EE), and in vitro drug release. Moreover, the in vitro cytotoxicity of NPs with three human cancer cell lines viz. HepG2, Hep3B, and SMCC-7721 was conducted using the SRB assay. Additionally, lyophilization was conducted to improve the long-term physical stability.

RESULTS

The GA-PEG-PLGA-ART NPs have spherical shape, small particle size (around 88 nm) with a narrow size distribution (PDI < 0.3), high drug LC (up to 59.3 ± 1.65%), and high EE (up to 73.13 ± 5.17%). In vitro drug release behavior showed that drugs were released from NPs in a sustained and controlled release pattern. Cytotoxicity study indicated the NPs achieved lower cancer cell survival fraction. The GA-PEG-PLGA NPs freeze-dried with 3% (w/v) of mannitol showed better effect on long-term physical stability.

CONCLUSION

The GA-PEG-PLGA-ART NPs appear as a potential liver targeted intracellular delivery platform for ART.

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.