Covalent, Non-Covalent, Encapsulated Nanodrug Regulate the Fate of Intra- and Extracellular Trafficking: Impact on Cancer and Normal Cells

Anticancer and antibacterial properties of carbon nanotubes are governed by their functional groups

Due to their high strength, low weight, and biologically-inspired dimensions, carbon nanotubes have found wide interest across all of medicine. In this study, four types of highly dispersible multi-walled carbon nanotubes (CNTs) of similar dimensions, but slightly different chemical compositions, were compared with an unmodified material to verify the impact their surface chemistry has on cytocompatibility, anticancer, inflammation, and antibacterial properties. Minute changes in the chemical composition were found to greatly affect the biological performance of the CNTs. Specifically, the CNTs with a large number of carbon atoms with a +2 coordination number induced cytotoxicity in macrophages and melanoma cells, and had a moderate antibacterial effect against Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria strains, all while being cytocompatible towards human dermal fibroblasts. Moreover, substituting some of the OH groups with ammonia diminished their cytotoxicity towards macrophages while still maintaining the aforementioned positive qualities. At the same time, CNTs with a large number of carbon atoms with a +3 coordination number had a high innate cytocompatibility towards normal healthy cells but were toxic towards cancer cells and bacteria. The latter was further boosted by reacting the CNTs' carboxyl groups with ammonia. Although requiring further analyses, the results of this study, thus, introduce new CNTs that without drugs can treat cancer, inflammation, and/or infection while still remaining cytocompatible with mammalian cells.

Molecular dynamics insight of interaction between the functionalized-carbon nanotube and cancerous cell membrane in doxorubicin delivery

BACKGROUND AND OBJECTIVE

Doxorubicin (DOX) is a known anticancer drug which is widely used in cancer therapy. Carbon nanotubes (CNTs) are among the most promising platforms for smart drug delivery applications. However, due to the toxicity and their low sulubility their application is limited and their functionalization with wide range of biomolecules are suggested. Therefore, the functionalized carbon nanotubes (f-CNT) with carboxyl (CNT-COO) and folic acid (CNT-COO-FA) were investigated as drug-carrier.

METHODS

Molecular dynamics (MD) simulation along with the Density Functional Theory (DFT) methods are being used to study the drug loading process on functionalized carbon nanotubes.

RESULTS

The results indicate that doxorubicin molecules interact more with CNT-COO-FA than CNT-COO. The embedded dipalmitoylphosphatidylcholine (DPPC) lipid bilayer with a folate receptor was considered a cancerous cell's representative model. Then the drug release from the f-CNTs near the lipid bilayer was simulated. The results showed that CNT-COO-FA with a pH and ligand-sensitive mechanism strongly interacts with cancerous cells, which led to higher drug release, in agreement with the experimental results. The conformational changes of the lipid bilayer and folate receptor during drug release were evaluated. The analysis showed that drug release from CNT-COO-FA has significantly changed lipid bilayer and receptor conformations. The obtained results were interpreted and justified by considering the molecular mechanisms which control the drug delivery in the studied systems.

CONCLUSIONS

Based on the obtained results, CNT-COO-FA has a better performance during the drug release compared to CNT-COO in delivering doxorubicin. Both pH and ligand sensitive mechanisms are found to be responsible for higher drug delivery efficiency of CNT-COO-FA. In contrast, CNT-COO can only enhance drug delivery efficiently with a pH-sensitive mechanism.

Functionalized Carbon Nanoparticles as Theranostic Agents and Their Future Clinical Utility in Oncology

Over the years, research of nanoparticle applications in pre-clinical and clinical applications has greatly advanced our therapeutic and imaging approaches to many diseases, most notably neoplastic disorders. In particular, the innate properties of inorganic nanomaterials, such as gold and iron oxide, as well as carbon-based nanoparticles, have provided the greatest opportunities in cancer theranostics. Carbon nanoparticles can be used as carriers of biological agents to enhance the therapeutic index at a tumor site. Alternatively, they can also be combined with external stimuli, such as light, to induce irreversible physical damaging effects on cells. In this review, the recent advances in carbon nanoparticles and their use in cancer theranostics will be discussed. In addition, the set of evaluations that will be required during their transition from laboratory investigations toward clinical trials will be addressed.

Synthesis and Characterization of a Novel Peptide Targeting Human Tenon Fibroblast Cells To Modulate Fibrosis: An Integrated Empirical Approach

Fibrosis is the primary factor influencing the prognosis of glaucoma post-trabeculectomy surgery, an eye condition characterized by increased intraocular pressure (IOP). Despite advancements in surgical procedures and aftercare, it continues to be a serious impediment. During the clinical intervention of scarring, fibrosis is managed by using topical application of combined antifibrotic drugs (mitomycin C). But still, scarring remains a key problem due to minimal drug penetration and nonbioavailability. In this study, we synthesized a cell-specific peptide for modulating scarring in human tenon fibroblasts undergoing epithelial-mesenchymal transition (EMT). The peptide was also conjugated with mitomycin C in order to investigate the effect of the drug conjugation on human tenon fibroblasts from the nanofiber composite system and to evaluate the fibrosis process. Peptide VRF2019 was identified using a subtractive proteomics approach, including solubility, cell penetration, and amphipathic properties. The peptide structure was determined using circular dichroism spectroscopy. The peptide and drug was conjugated using N-ethyl-N'-(3-(dimethylamino)propyl) carbodiimide/N-hydroxysuccinimide (EDC-NHS) chemistry, and the conjugation efficiency was evaluated using high-pressure liquid chromatography. The conjugated product and polycaprolactone (PCL) were electrospun to form a composite nanofiber, which was tested for cytotoxicity and drug release on human tenon fibroblast cells. The modeled VRF2019 peptide structure formed an α-helical structure with all residues spanning the allowed regions of the Ramachandran plot. Subsequent molecular dynamics simulations also demonstrated its membrane penetration potential. The peptide uptake was also studied in human tenon fibroblast cells. High-pressure liquid chromatography (HPLC) and mass spectrometry measurements confirmed peptide-drug conjugation and stability. Furthermore, scanning electron microscopy (SEM) investigation revealed the structure and size of the PCL composite nanofiber. We infer from early research that the PCL composite nanofiber matrix can greatly increase drug delivery and bioavailability.

Doxorubicin-Loaded Polymeric Micelles Conjugated with CKR- and EVQ-FLT3 Peptides for Cytotoxicity in Leukemic Stem Cells

Doxorubicin (Dox) is the standard chemotherapeutic agent for acute myeloblastic leukemia (AML) treatment. However, 40% of Dox-treated AML cases relapsed due to the presence of leukemic stem cells (LSCs). Thus, poloxamer 407 and CKR- and EVQ-FLT3 peptides were used to formulate Dox-micelles (DMs) and DM conjugated with peptides (CKR and EVQ) for improving AML-LSC treatment. Results indicated that DMs with a weight ratio of Dox to P407 of 1:200 had a particle size of 23.3 ± 1.3 nm with a high percentage of Dox entrapment. They were able to prolong drug release and maintain physicochemical stability. Following effective DM preparation, P407 was modified and conjugated with FLT3 peptides, CKR and EVQ to formulate DM-CKR, DM-EVQ, and DM-CKR+DM-EVQ. Freshly synthesized DMs displaying FLT3 peptides showed particle sizes smaller than 50 nm and a high drug entrapment level, comparable with DMs. DM-CKR+DM-EVQ was considerably more toxic to KG-1a (AML LSC-like cell model) than Dox-HCl. These FLT3-targeted DMs could increase drug uptake and induce apoptosis induction. Due to an increase in micelle-LSC binding and uptake, DMs displaying both peptides tended to improve the potency of Dox compared to a single peptide-coupled micelle.

Application of Carbon Nanoparticles in Oncology and Regenerative Medicine

Currently, carbon nanoparticles play a large role as carriers of various types of drugs, and also have applications in other fields of medicine, e.g., in tissue engineering, where they are used to reconstruct bone tissue. They also contribute to the early detection of cancer cells, and can act as markers in imaging diagnostics. Their antibacterial and anti-inflammatory properties are also known. This feature is particularly important in dental implantology, where various types of bacterial infections and implant rejection often occur. The search for newer and more effective treatments may lead to future use of nanoparticles on a large scale. In this work, the current state of knowledge on the possible use of nanotubes, nanodiamonds, and fullerenes in therapy is reviewed. Both advantages and disadvantages of the use of carbon nanoparticles in therapy and diagnostics have been indicated.

Structural Deformation of MTX Induced by Nanodrug Conjugation Dictate Intracellular Drug Transport and Drug Efficacy

BACKGROUND

Understanding structural interactions between the active drug and conjugated nanoparticles is critical for optimizing intracellular drug transport and for increasing nano drug efficacy. In this regard, analyzing the conformational deformation of conjugated drugs surrounding nanoparticles is essential to understand the corresponding nanodrug efficacy.

PURPOSE

The objective of this study is to present an optimal synthesis method for efficient drug delivery through a clear structural analysis of nanodrugs according to the type of conjugation.

METHODS AND RESULTS

In this study, the structural variation of methotrexate (MTX) surrounding carbon nanotubes, depending on the type of conjugation style, such as covalent and non-covalent (PEGylation) bonds, was investigated. Specifically, covalent bonds of MTX surrounding CNTs induced greater structural deformation compared to non-covalent bonds (ie, PEGylated CNT).

CONCLUSION

Greater changes in the structural variations of MTX analyzed by nuclear magnetic resonance (NMR) significantly improved the anti-inflammatory drug efficacy of human fibroblast-like synovial cells (FLS) via stable drug release in the extracellular environment and burst drug release under intracellular conditions.

Understanding the Uptake Mechanism and Interaction Potential of the Designed Peptide and Preparation of Composite Fiber Matrix for Fungal Keratitis

The conventional use of antibiotics for the treatment of infectious keratitis currently faces two major challenges: poor drug penetration and the emergence of antibiotic resistance in microbial strains. Cell-penetrating peptides (CPPs) with antimicrobial properties have the potential to address these challenges. However, their mode of action, mechanism of uptake, and interaction potential have not been explored in detail. In this study, we probed the mechanism of uptake and interaction potential of our previously designed peptides (VRF005 and VRF007). Our results showed that VRF005 undergoes direct translocation and induces a rough membrane surface, whereas VRF007 undergoes clathrin-mediated endocytic uptake. The gel shift assay showed that VRF005 is bound to genomic DNA, whereas VRF007 is bound to chitin and β-d-glucan. Gene expression studies revealed the effect of peptide VRF005 on Candida albicans transcription. Molecular docking and simulations showed that VRF005 forms noncovalent interactions (such as H-bonding and water bridges) with natamycin. It exhibited synergistic antifungal activity in the colony-forming assay. VRF005, functionalized in the polycaprolactone fiber matrix, showed sustained delivery and antifungal activity.

Functionalized Carbon Nanostructures Versus Drug Resistance: Promising Scenarios in Cancer Treatment

Carbon nanostructures (CN) are emerging valuable materials for the assembly of highly engineered multifunctional nanovehicles for cancer therapy, in particular for counteracting the insurgence of multi-drug resistance (MDR). In this regard, carbon nanotubes (CNT), graphene oxide (GO), and fullerenes (F) have been proposed as promising materials due to their superior physical, chemical, and biological features. The possibility to easily modify their surface, conferring tailored properties, allows different CN derivatives to be synthesized. Although many studies have explored this topic, a comprehensive review evaluating the beneficial use of functionalized CNT vs G or F is still missing. Within this paper, the most relevant examples of CN-based nanosystems proposed for MDR reversal are reviewed, taking into consideration the functionalization routes, as well as the biological mechanisms involved and the possible toxicity concerns. The main aim is to understand which functional CN represents the most promising strategy to be further investigated for overcoming MDR in cancer.

Apoptotic lysosomal proton sponge effect in tumor tissue by cationic gold nanorods

Despite the lysosomal "proton sponge hypothesis" being considered to be an additional factor for stimulating the cellular toxicity of nanoparticle-based drug delivery systems, a clear relationship between the massive influx of calcium ions and the proton sponge effect, both of which are associated with cancer cell apoptosis, has still not been elucidated. Cetrimonium bromide (CTAB: cationic quaternary amino group based) gold nanorods possessed a more effective electric surface charge for inducing the lysosomal proton sponge effect than anionic gold nanoparticles. In this aspect, identifying released cytoplasmic Cl^-, arising from the ruptured lysosomal compartment, in the cytoplasm is critical for supporting the "proton sponge hypothesis". This study clarified that the burst release of Cl^-, as a result of lysosomal swelling by CTAB gold nanorods, stimulates the transient receptor potential channels melastatin 2 (TRPM2) channels, and subsequently induces a massive Ca²⁺ influx, which independently increases apoptosis of cancer cells. Although the previous concept of elevated cancer apoptosis acting through the proton sponge effect is unclear, this study supports the evidence that a massive Ca²⁺ influx mediated in response to a burst release of Cl^- significantly influenced cytotoxicity of cancer cells in tumor tissues.

Hydrophilic Fluorescent Nanoprodrug of Paclitaxel for Glioblastoma Chemotherapy

Highly water-soluble, nontoxic organic nanoparticles on which paclitaxel (PTX), a hydrophobic anticancer drug, has been covalently bound via an ester linkage (4.5% of total weight) have been prepared for the treatment of glioblastoma. These soft fluorescent organic nanoparticles (FONPs), obtained from citric acid and diethylenetriamine by microwave-assisted condensation, show suitable size (Ø = 17-30 nm), remarkable solubility in water, softness as well as strong blue fluorescence in an aqueous environment that are fully retained in cell culture medium. Moreover, these FONPs were demonstrated to show in vitro safety and preferential internalization in glioblastoma cells through caveolin/lipid raft-mediated endocytosis. The PTX-conjugated FONPs retain excellent solubility in water and remain stable in water (no leaching), while they showed anticancer activity against glioblastoma cells in two-dimensional and three-dimensional culture. PTX-specific effects on microtubules reveal that PTX is intracellularly released from the nanocarriers in its active form, in relation with an intracellular-promoted lysis of the ester linkage. As such, these hydrophilic prodrug formulations hold major promise as biocompatible nanotools for drug delivery.

Destroying Deep Lung Tumor Tissue through Lung-Selective Accumulation and by Activation of Caveolin Uptake Channels Using a Specific Width of Carbon Nanodrug

The main difficulty with current anticancer nanotherapeutics comes from the low efficiency of tumor targeting. Although many strategies have been investigated, including cancer-specific antibody conjugation, lung tumors remain one of the invulnerable types of cancer that must be overcome in the near future. Meanwhile, despite their advantageous physiochemical properties, carbon nanotube structures are not considered safe medical drug delivery agents, but are considered a hazardous source that may cause pulmonary toxicity. However, high-aspect-ratio (width vs. length) nanostructures can be used as very efficient drug delivery agents due to their lung tissue accumulation property. Furthermore, selection of a specific width of the carbon nanostructures can activate additional caveolin uptake channels in cancer cells, thereby maximizing internalization of the nanodrug. The present study aimed to evaluate the therapeutic potential of carbon nanotube-based nanodrugs having various widths (10-30 nm, 60-100 nm, and 125-150 nm) as a delivery agent to treat lung tumors. The results of the present study provided evidence that both lung tissue accumulation (passive targeting) and caveolin-assisted uptake (active targeting) can simultaneously contribute to the destruction of lung tumor tissues of carbon nanotube.

PEGylated anticancer-carbon nanotubes complex targeting mitochondria of lung cancer cells

Although activating apoptosis in cancer cells by targeting the mitochondria is an effective strategy for cancer therapy, insufficient targeting of the mitochondria in cancer cells restricts the availability in clinical treatment. Here, we report on a polyethylene glycol-coated carbon nanotube (CNT)-ABT737 nanodrug that improves the mitochondrial targeting of lung cancer cells. The polyethylene glycol-coated CNT-ABT737 nanodrug internalized into the early endosomes via macropinocytosis and clathrin-mediated endocytosis in advance of early endosomal escape and delivered into the mitochondria. Cytosol release of the nanodrug led to apoptosis of lung cancer cells by abruption of the mitochondrial membrane potential, inducing Bcl-2-mediated apoptosis and generating intracellular reactive oxygen species. As such, this study provides an effective strategy for increasing the anti-lung cancer efficacy by increasing mitochondria accumulation rate of cytosol released anticancer nanodrugs.