Bioreducible exosomes encapsulating glycolysis inhibitors potentiate mitochondria-targeted sonodynamic cancer therapy via cancer-targeted drug release and cellular energy depletion.

Nanocarrier-assisted sonodynamic therapy (SDT) has shown great potential for the effective and targeted treatment of deep-seated tumors by overcoming the critical limitations of sonosensitizers. However, in vivo SDT using nanocarriers is still constrained by their intrinsic toxicity and nonspecific cargo release. In this study, we developed bioreducible exosomes for the safe and tumor-specific delivery of mitochondria-targeting sonosensitizers [triphenylphosphonium-conjugated chlorin e6 (T-Ce6)] and glycolysis inhibitors (FX11). Redox-cleavable diselenide linker-bearing lipids were embedded into exosomes to trigger drug release in response to overexpressed glutathione in the tumor microenvironment. Bioreducible exosomes facilitate the cytoplasmic release of their payload in the reducing environment of tumor cells. They significantly enhance drug release and sonodynamic effects when irradiated with ultrasound (US). The mitochondria-targeted accumulation of T-Ce6 efficiently damaged the mitochondria of the cells under US irradiation, accelerating apoptotic cell death. FX11 substantially inhibited cellular energy metabolism, potentiating the antitumor efficacy of mitochondria-targeted SDT. Bioreducible exosomes effectively suppressed tumor growth in mice without significant systemic toxicity, via a combination of mitochondria-targeted SDT and energy metabolism-targeted therapy. This study offers new insights into the use of dual stimuli-responsive exosomes encapsulating sonosensitizers for safe and targeted sonodynamic cancer therapy.

Piezocatalytic 2D WS2 Nanosheets for Ultrasound-Triggered and Mitochondria-Targeted Piezodynamic Cancer Therapy Synergized with Energy Metabolism-Targeted Chemotherapy.

Piezoelectric nanomaterials that can generate reactive oxygen species (ROS) by piezoelectric polarization under an external mechanical force have emerged as an effective platform for cancer therapy. In this study, piezoelectric 2D WS2 nanosheets are functionalized with mitochondria-targeting triphenylphosphonium (TPP) for ultrasound (US)-triggered, mitochondria-targeted piezodynamic cancer therapy. In addition, a glycolysis inhibitor (FX11) that can inhibit cellular energy metabolism is loaded into TPP- and poly(ethylene glycol) (PEG)-conjugated WS2 nanosheet (TPEG-WS2 ) to potentiate its therapeutic efficacy. Upon US irradiation, the sono-excited electrons and holes generated in the WS2 are efficiently separated by piezoelectric polarization, which subsequently promotes the production of ROS. FX11-loaded TPEG-WS2 (FX11@TPEG-WS2 ) selectively accumulates in the mitochondria of human breast cancer cells. In addition, FX11@TPEG-WS2 effectively inhibits the production of adenosine triphosphate . Thus, FX11@TPEG-WS2 exhibits outstanding anticancer effects under US irradiation. An in vivo study using tumor-xenograft mice demonstrates that FX11@TPEG-WS2 effectively accumulated in the tumors. Its tumor accumulation is visualized using in vivo computed tomography . Notably, FX11@TPEG-WS2 with US irradiation remarkably suppresses the tumor growth of mice without systemic toxicity. This study demonstrates that the combination of piezodynamic therapy and energy metabolism-targeted chemotherapy using mitochondria-targeting 2D WS2 is a novel strategy for the selective and effective treatment of tumors.

Mitochondria-targeting sonosensitizer-loaded extracellular vesicles for chemo-sonodynamic therapy.

Sonodynamic therapy (SDT) has emerged as an effective therapeutic modality as it employs ultrasound (US) to eradicate deep-seated tumors noninvasively. However, the therapeutic efficacy of SDT in clinical settings remains limited owing to the low aqueous stability and poor pharmacokinetic properties of sonosensitizers. In this study, extracellular vesicles (EVs), which have low systemic toxicity, were used as clinically available nanocarriers to effectively transfer a sonosensitizer to cancer cells. Chlorin e6 (Ce6), a sonosensitizer, was conjugated to a mitochondria-targeting triphenylphosphonium (TPP) moiety and loaded into EVs to enhance the efficacy of SDT, because mitochondria are critical subcellular organelles that regulate cell survival and death. Additionally, piperlongumine (PL), a pro-oxidant and cancer-specific chemotherapeutic agent, was co-encapsulated into EVs to achieve efficient and selective anticancer activity. The EVs substantially amplified the cellular internalization of TPP-conjugated Ce6 (TPP-Ce6), resulting in the enhanced generation of intracellular reactive oxygen species (ROS) in MCF-7 human breast cancer cells upon US exposure. Importantly, EVs encapsulating TPP-Ce6 effectively destroyed the mitochondria under irradiation with US, leading to efficient anticancer activity. The co-encapsulation of pro-oxidant PL into EVs significantly enhanced the SDT efficacy in MCF-7 cells through the excessive generation of ROS. Moreover, the EV co-encapsulating TPP-Ce6 and PL [EV(TPP-Ce6/PL)] exhibited cancer-specific cell death owing to the cancer-selective apoptosis triggered by PL. In vivo study using MCF-7 tumor-xenograft mice revealed that EV(TPP-Ce6/PL) effectively accumulated in tumors after intravenous injection. Notably, treatment with EV(TPP-Ce6/PL) and US inhibited tumor growth significantly without causing systemic toxicity. This study demonstrated the feasibility of using EV(TPP-Ce6/PL) for biocompatible and cancer-specific chemo-SDT.

Immunomodulatory nanosystems for treating inflammatory diseases.

Inflammatory disease (ID) is an umbrella term encompassing all illnesses involving chronic inflammation as the central manifestation of pathogenesis. These include, inflammatory bowel diseases, hepatitis, pulmonary disorders, atherosclerosis, myocardial infarction, pancreatitis, arthritis, periodontitis, psoriasis. The IDs create a severe burden on healthcare and significantly impact the global socio-economic balance. Unfortunately, the standard therapies that rely on a combination of anti-inflammatory and immunosuppressive agents are palliative and provide only short-term relief. In contrast, the emerging concept of immunomodulatory nanosystems (IMNs) has the potential to address the underlying causes and prevent reoccurrence, thereby, creating new opportunities for treating IDs. The IMNs offer exquisite ability to precisely modulate the immune system for a therapeutic advantage. The nano-sized dimension of IMNs allows them to efficiently infiltrate lymphatic drainage, interact with immune cells, and subsequently to undergo rapid endocytosis by hyperactive immune cells (HICs) at inflamed sites. Thus, IMNs serve to restore dysfunctional or HICs and alleviate the inflammation. We identified that different IMNs exert their immunomodulatory action via either of the seven mechanisms to modulate; cytokine production, cytokine neutralization, cellular infiltration, macrophage polarization, HICs growth inhibition, stimulating T-reg mediated tolerance and modulating oxidative-stress. In this article, we discussed representative examples of IMNs by highlighting their rationalization, design principle, and mechanism of action in context of treating various IDs. Lastly, we highlighted technical challenges in the application of IMNs and explored the future direction of research, which could potentially help to overcome those challenges.

Pro-Oxidant Drug-Loaded Au/ZnO Hybrid Nanoparticles for Cancer-Specific Chemo-Photodynamic Combination Therapy.

Photodynamic therapy (PDT) is a noninvasive therapeutic strategy involving photosensitizers and external light for the selective destruction of target tumors. Chemo-photodynamic combination therapy has attracted widespread attention to improve the outcome of cancer treatment by PDT only. In this study, light-triggered reactive oxygen species (ROS)-generating, polyethylene glycol (PEG)-coated zinc oxide nanorods (PEG-ZnO NRs) were synthesized and complexed with pro-oxidant piperlongumine (PL) to achieve cancer-targeted chemo-photodynamic combination therapy. It was found that PEG-ZnO NRs considerably increased intracellular ROS under UV light irradiation. The loading of PL to PEG-ZnO NRs further increased the intracellular ROS levels in MCF-7 human breast cancer cells due to efficient intracellular delivery of PL. As a result, PL-loaded PEG-ZnO NRs (PL-PEG-ZnO NRs) exhibited a synergistic anticancer activity under UV irradiation compared to free PL and PEG-ZnO NRs. PEG-ZnO NRs were further modified with Au NPs to enhance their capability of generating ROS under light. Au NP-coated PEG-ZnO NRs (Au/PEG-ZnO NRs) with UV irradiation showed higher ROS quantum yields as compared to PEG-ZnO NRs. As a result, PL-loaded Au/PEG-ZnO NRs (PL-Au/PEG-ZnO NRs) exhibited higher cytotoxicity than PL-PEG-ZnO NRs upon UV irradiation. Moreover, PL-Au/PEG-ZnO NRs showed cancer-specific cytotoxicity in MCF-7 cells due to the cancer-specific apoptosis induced by pro-oxidant PL. This study demonstrates that PL-Au/PEG-ZnO NRs have high potential for efficient and cancer-targeted chemo-photodynamic combination therapy.

Polysorbate Surfactants as Drug Carriers: Tween 20-Amphotericin B Conjugates as Anti-Fungal and Anti-Leishmanial Agents.

BACKGROUND: Amphotericin B (AmB), a polyene antibiotic used for the treatment of fungal and leishmanial infections is virtually insoluble in water and exhibits severe toxicity. AmB has been conjugated to various soluble polymers for improving its solubility and reducing its toxicity. Conjugating AmB to a polysorbate surfactant such as polyoxyethylene sorbitan monolaurate (Tween 20), was examined to improve its solubility and reduce its toxicity. METHODS: AmB was coupled to Tween 20 via carbamate linkage at 15 and 30 wt% concentrations in high yield by activating the hydroxyl groups of the surfactant using p- nitrophenyl chloroformate. The conjugates were characterized by using 1H NMR, IR, UV and HPLC analysis and were examined for their toxicity, and anti-fungal and anti-leishmanial activities in vitro. RESULTS: Tween-AmB conjugates were soluble to the extent of 10 mg/mL in water, showed improved critical micelle concentration in comparison with AmB, exhibited negligible hemolytic potential even at a concentration of 1000 µM and were not toxic against human embryonic kidney cell line (HEK293T) at similar concentrations. The conjugates showed potent anti-fungal activity against Candida albicans, Candida parapsilosis and Cryptococcus neoformans and anti-leishmanial activity against intramacrophage amastigotes of Leishmania donovani. CONCLUSIONS: Tween 20 is a surfactant approved by the US FDA as an additive in food and pharmaceutical preparations. Synthesis of drug conjugates with surfactants such as Tween-20 could open up new opportunities to improve the solubility of many drugs, reduce their toxicity and could possibly target the brain as polysorbates known to facilitate nanoparticulate systems to cross the blood-brain barrier.

Synthetic Polysaccharides as Drug Carriers: Synthesis of Polyglucose-Amphotericin B Conjugates and In Vitro Evaluation of Their Anti-Fungal and Anti-Leishmanial Activities.

While many naturally occurring polysaccharides have been widely used as drug carriers, there are two main drawbacks in their use: the first is their physical properties such as molecular weight, branching, type of glycosidic linkages and solubility depend on their source and the method of isolation and purification, the second is many of them are contaminated with proteins and protein removal is essential for preventing immune reactions. Synthetic polysaccharides on the other hand can be tailor made from their respective monomers with consistent physical properties and are, free from protein contamination, both being significant advantages in their use. Although, the synthesis of polysaccharides such as polyglucose, polymannose, polygalactose etc., by the polycondensation of their respective monomers have been reported more than half a century ago, their use as drug carriers have not received any attention so far. In this report, we show that polyglucose (PG) having a weight average molar mass of 37,000 g/mol can be synthesized in a single step by the melt polycondensation of glucose in over 70% yield. Oxidation using sodium periodate generated aldehyde functions on the polymer. Amphotericin B, (AmB) a water-insoluble polyene antibiotic was chosen as a model drug to couple onto periodate oxidized PG via imine linkage at ~20 wt% concentration. The drug loading capacity of the conjugates was above 90%. Further reduction using sodium borohydride gave the more stable amine conjugates with any residual aldehyde on the polymer backbone getting reduced to hydroxyl groups. The conjugates were highly soluble in water and stable on storage. At ten times the concentration of AmB, the conjugates produced negligible hemolysis to human blood. The AmB conjugates were then evaluated for their anti-fungal activity against C. albicans and A. fumigatus and anti-leishmanial activity against different strains of L. donovani in culture. The conjugates showed potent anti-fungal and anti-leishmanial activity. The use of synthetic polysaccharides in drug delivery and in other biomedical applications will have many potential advantages.

Synthesis and evaluation of anti-fungal activities of sodium alginate-amphotericin B conjugates.

Sodium alginate (SA) was oxidized using periodate and amphotericin B (AmB) was conjugated via imine and amine linkages to the oxidized alginate. Oxidization drastically reduced the molecular weight (MW) of the alginate. The conjugates were highly water-soluble to the extent of 1000mg/mL making them useful for therapeutic applications. SA-AmB conjugates derived from 20 and 50% oxidized alginate were non-toxic to HEK 293T and RAW 264.7 cell line at 100µg/mL and was also non-hemolytic to human blood at 100µg/mL. In vitro release of AmB into phosphate buffer from the imine conjugates was negligible with less than 0.2% of the drug released in 48h. Capping of residual aldehyde handles using 2-ethanolamine or glycine resulted in increased release of the drug in vitro. Injectable gels of gelatin crosslinked with oxidized alginate incorporating the SA-AmB conjugates as well as AmB were also fabricated and drug release was examined. In vitro release from the gel discs showed that AmB was released to the extent of 15-20% in 2days. The SA-AmB conjugates showed potent anti-fungal activity against C. albicans, C. neoformans and C. parapsilosis. The injectable gels seem to have potential for prolonged release of AmB when implanted.

Tyrosine-derived novel antimicrobial hydantoin polymers: synthesis and evaluation of anti-bacterial activities.

A new approach for the design and synthesis of cyclic N-halamine polymers having anti-bacterial activity based on a vinyl derivative of tyrosine-derived hydantoin is reported. The synthesis of N-halamine polymers generally involves the chemical modification of 5,5'-disubstituted hydantoin to introduce polymerizable vinyl moieties thereby restricting the halogen capture only on the amide nitrogen. Here we show the possibility of synthesizing vinyl monomers of N-halamine from α-amino acids wherein both the amide and imide nitrogens are available for halogen capture. Thus, a hydantoin monomer was synthesized from L-tyrosine and copolymerized with methyl methacrylate and 2-(hydroxyethyl)methacrylate, to obtain random co-polymers. The monomer and its co-polymers were characterized using NMR, IR, HRMS, GPC, DSC, EDAX and TGA analysis. Films of the co-polymers cast from 10% acetone solutions were exposed to sodium hypochlorite solution to activate the hydantoin moieties. The oxidative chlorine content of the films ranged from 0.6 to 0.9%. The activated films were exposed to both Gram positive (S. aureus) and Gram negative (E. coli) bacteria using standard protocols. Polymers having chlorine content as little as 0.6% exhibited 6 log reduction in the bacterial growth within 30 min of exposure. The method allows the halogenation of both amide and imide nitrogens and could be applied to the preparation of a number of vinyl hydantoins from many amino acids.