Cancer-Related Intracellular Signalling Pathways Activated by DOXorubicin/Cyclodextrin-Graphene-Based Nanomaterials.

In the last decade, nanotechnological progress has generated new opportunities to improve the safety and efficacy of conventional anticancer therapies. Compared with other carriers, graphene nanoplatforms possess numerous tunable functionalities for the loading of multiple bioactive compounds, although their biocompatibility is still a debated concern. Recently, we have investigated the modulation of genes involved in cancer-associated canonical pathways induced by graphene engineered with cyclodextrins (GCD). Here, we investigated the GCD impact on cells safety, the HEp-2 responsiveness to Doxorubicin (DOX) and the cancer-related intracellular signalling pathways modulated by over time exposure to DOX loaded on GCD (GCD@DOX). Our studies evidenced that both DOX and GCD@DOX induced p53 and p21 signalling resulting in G0/G1 cell cycle arrest. A genotoxic behaviour of DOX was reported via detection of CDK (T14/Y15) activation and reduction of Wee-1 expression. Similarly, we found a cleavage of PARP by DOX within 72 h of exposure. Conversely, GCD@DOX induced a late cleavage of PARP, which could be indicative of less toxic effect due to controlled release of the drug from the GCD nanocarrier. Finally, the induction of the autophagy process supports the potential recycling of DOX with the consequent limitation of its toxic effects. Together, these findings demonstrate that GCD@DOX is a biocompatible drug delivery system able to evade chemoresistance and doxorubicin toxicity.

Simulation and computational study of graphene oxide nano-carriers, absorption, and release of the anticancer drug of camptothecin.

The structure of nano-graphene oxide has attracted special attention in drug release due to its special properties such as hydrophilicity, special surface, biocompatibility, and the possibility of high loading of hydrophilic and hydrophobic drugs. In this study, after simulating and optimizing the structure of nano-graphene and then nano-graphene oxide (NGO), it was used to load the anti-cancer drug of camptothecin (CA) in an aqueous medium, and the optimal conditions for achieving maximum loading efficiency of the drug were investigated. Due to the structure of the drug, there are two forms, one form of lactone ring and the other carboxylate. If the lactone ring form is predominant, the effectiveness of the drug is increased. This depends on pH of the environment. The calculated thermodynamic and structural results show that the solubility of the drug about nano-graphene and its lactone ring state is maintained by using nano-graphene oxide. To increase the effectiveness of the drug, the lactone ring form must be maintained in the drug structure. The use of folic acid as an intermediate in the aqueous medium preserves the lactone form in the drug structure and increases its effectiveness. The results show that the presence of the ring in the drug structure and its binding to the mediator of folic acid to nano-graphene oxide is a stabilizing factor of keto tautomer. The calculation of vibrational frequencies shows that the presence of folic acid intermediate reduces the vibrational frequency of the hydroxyl group (OH) so that its absorption energy (Ead) is equal to the lowest value 65.24 a.u.

Graphene Oxide Loaded with Protocatechuic Acid and Chlorogenic Acid Dual Drug Nanodelivery System for Human Hepatocellular Carcinoma Therapeutic Application.

Hepatocellular carcinoma or hepatoma is a primary malignant neoplasm that responsible for 75-90% of all liver cancer in humans. Nanotechnology introduced the dual drug nanodelivery method as one of the initiatives in nanomedicine for cancer therapy. Graphene oxide (GO) loaded with protocatechuic acid (PCA) and chlorogenic acid (CA) have shown some anticancer activities in both passive and active targeting. The physicochemical characterizations for nanocomposites were conducted. Cell cytotoxicity assay and lactate dehydrogenase were conducted to estimate cell cytotoxicity and the severity of cell damage. Next, nanocomposite intracellular drug uptake was analyzed using a transmission electron microscope. The accumulation and localization of fluorescent-labelled nanocomposite in the human hepatocellular carcinoma (HepG2) cells were analyzed using a fluorescent microscope. Subsequently, Annexin V- fluorescein isothiocyanate (FITC)/propidium iodide analysis showed that nanocomposites induced late apoptosis in HepG2 cells. Cell cycle arrest was ascertained at the G2/M phase. There was the depolarization of mitochondrial membrane potential and an upregulation of reactive oxygen species when HepG2 cells were induced by nanocomposites. In conclusion, HepG2 cells treated with a graphene oxide-polyethylene glycol (GOP)-PCA/CA-FA dual drug nanocomposite exhibited significant anticancer activities with less toxicity compared to pristine protocatechuic acid, chlorogenic acid and GOP-PCA/CA nanocomposite, may be due to the utilization of a folic acid-targeting nanodrug delivery system.

One-stop radiotherapeutic targeting of primary and distant osteosarcoma to inhibit cancer progression and metastasis using 2DG-grafted graphene quantum dots.

The application of radiotherapy (RT) to treat osteosarcoma (OS) has been limited, but this is starting to change as the ability to target radiation energy to niches improves. Furthermore, lung cancer from highly metastatic OS is a major cause of death, so it is critical to explore new strategies to tackle metastasis. In this study, we designed a nanoscale radiosensitizer by grafting 2-deoxy-d-glucose (2DG) onto graphene quantum dots (GQD) to achieve OS targeting and boost RT efficacy. Combining the use of 2DG-grafted GQDs (2DG-g-GQD) with RT produced a significant increase in oxidative stress response and DNA damage in the 143B OS cell line compared with RT alone. Moreover, 2DG-g-GQDs selectively associated with 143B cells, and demonstrated the inhibition of migration in a scratch assay. We also demonstrated remarkable improvement in their ability to inhibit tumour progression and lung metastasis in an OS xenograft mouse model. Our results show that the use of 2DG-g-GQDs as OS-targeting radiosensitizers improves their therapeutic outcome and exhibits potential for use in low-dose precision RT for OS.

Enhancement radiation-induced apoptosis in C6 glioma tumor-bearing rats via pH-responsive magnetic graphene oxide nanocarrier.

5-iodo-2-deoxyuridine (IUdR) has been demonstrated to induce an appreciable radiosensitizing effect on glioblastoma patients, but due to the short circulation half-life times and failure to pass through the blood-brain barrier (BBB), its clinical use is limited. Accordingly, in this study, we used magnetic graphene oxide (NGO/SPIONs) nanoparticles coated with PLGA polymer as a dynamic nanocarrier for IUdR and, evaluated its sensitizing enhancement ratio in combination with a single dose X-ray at clinically megavoltage energies for treatment of C6 glioma rats. Nanoparticles were characterized using Zetasizer and TEM microscopy, and in vitro biocompatibility of nanoparticles was assessed with MTT assay. IUdR/MNPs were intravenously administered under a magnetic field (1.3 T) on day 13 after the implantation of C6 cells. After a day following the injection, rats exposed with radiation (8 Gy). ICP-OES analysis data indicated an effective magnetic targeting, leading to remarkably improved penetration through the BBB. In vivo release analysis with HPLC indicated sustained release of IUdR and, prolonged the lifespan in plasma (P < .01). In addition, our findings revealed a synergistic effect for IUdR/MNPs coupled with radiation, which significantly inhibited the tumor expansion (>100%), prolonged the survival time (>100%) and suppressed the anti-apoptotic response of glioma rats by increasing Bax/Bcl-2 ratio (2.13-fold) in compared with the radiation-only. In conclusion, besides high accumulation in targeted tumor sites, the newly developed IUdR/MNPs, also exhibited the ability of IUdR/MNPs to significantly enhance radiosensitizing effect, improve therapeutic efficacy and increase toxicity for glioma-bearing rats.

Chelating ZnO-dopamine on the surface of graphene oxide and its application as pH-responsive and antibacterial nanohybrid delivery agent for doxorubicin.

In this work, a new pH-responsive nanohybrid carrier was prepared with chelating ZnO-dopamine (Zn-d) on the surface of graphene oxide. Doxorubicin (DOX) as a model drug was loaded on the resulted nanohybrid. The characteristics of Zn-d-rGO nanohybrid (NH) determined using Fourier transformed infrared spectroscopy (FT-IR), X-ray Diffraction spectroscopy (XRD), UV-Visible spectroscopy, Scanning Electron Microscope (SEM), EDX and AFM. The BET analysis showed a specific surface area of 37.16 m2/g and the obtained nanohybrid indicated a high loading capacity of DOX up to 99.7%, and the release profile displayed a pH-dependent discharge in the acidic environment for14 days. The cytotoxicity of the prepared nanohybrid was measured against T47D and MCF10A cells and it confirmed that as-prepared nanohybrid has high toxicity against cancer cells and lower effect against human breast cell. Meanwhile, the prepared nanohybrids showed well antimicrobial activity against gram-positive and negative bacteria. The obtained results showed that the prepared nanohybrid (Zn-d-rGO) could potentially be used as a safe carrier for drug delivery systems.

Graphene quantum dot cross-linked carboxymethyl cellulose nanocomposite hydrogel for pH-sensitive oral anticancer drug delivery with potential bioimaging properties.

Herein, graphene quantum dots (GQDs) were introduced as a novel and safe crosslinker for carboxymethyl cellulose to make biodegradable and biocompatible hydrogels. The casting was used as a simple method for the preparation of the CMC/GQDs films. Effects of the GQDs percentage on the physicochemical properties of the films were studied, and several characterizations were performed including Fourier transform infrared spectroscopy, UV-vis spectroscopy, scanning electron microscopy, gas permeability, and mechanical testing analysis. The CMC/GQDs showed a pH-sensitive swelling and degradation with improved tensile strength. Fluorescent properties were also studied to evaluate the potential of the prepared CMC/GQDs nanocomposite for fluorescent bioimaging applications. Drug delivery property of the CMC-GQDs were studied using doxorubicin (DOX) as a model anticancer drug. Cytotoxicity studies were carried out using human colon adenocarcinoma HT29 cells. The prepared CMC/GQDs exhibited biocompatibility and pH-sensitive drug delivery behavior which proposed the prepared nanocomposite hydrogel has the potential to be used as a pH-triggered site-specific drug delivery system.

Poly(N,N-diethyl acrylamide)/functionalized graphene quantum dots hydrogels loaded with doxorubicin as a nano-drug carrier for metastatic lung cancer in mice.

Cancer has emanated as a daunting menace to human-kind even though medicine, science, and technology has reached its zenith. Subsequent scarcity in the revelation of new drugs, the exigency of salvaging formerly discovered toxic drugs such as doxorubicin has emerged. The invention of drug carrier has made drug delivery imminent which is ascribable to its characteristic traits of specific targeting, effective response to stimuli and biocompatibility. In this paper, the nanoscale polymeric drug carrier poly(N,N-diethyl acrylamide) nanohydrogel has been synthesized by inverse emulsion polymerization. Lower critical solution temperature of the polymeric carrier has been modified using graphene quantum. The particle size of pure nanohydrogel was in the range of 47 to 59.5 nm, and graphene quantum dots incorporated nanohydrogels was in the range of 68.1 to 87.5 nm. Doxorubicin (hydroxyl derivative of anthracycline) release behavior as a function of time and temperature was analyzed, and the Lower critical solution temperature of the synthesized nanohydrogels has been found to be in the range of 28-42 °C. Doxorubicin release characteristics have improved significantly as the surrounding temperature of the release media was increased near to physiological temperature. Further, the cumulative release profile was fitted in the different kinetic model and found to follow a Fickian diffusion release mechanism. The hydrogel was assessed for its cytotoxicity in B16F10 cells by MTT assay. In-vivo studies were done to study the lung metastasis by melanoma cancer and the results showed a rational favorable prognosis which was confirmed by evaluating hematological parameters and the non-immunogenic nature of nanohydrogel by cytokine assay. Comprehensively, the results suggested that poly(N,N-diethyl acrylamide) nanohydrogels have potential application as an intelligent drug carrier for melanoma cancer.

Mannosylated graphene oxide as macrophage-targeted delivery system for enhanced intracellular M.tuberculosis killing efficiency.

Tuberculosis (TB), caused by M.tuberculosis (Mtb), has become a top killer among infectious diseases. Enhancing the ability of anti-TB drugs to kill intracellular Mtb in host cells remains a big challenge. Here, an innovative nano-system was developed to increase drug delivery and Mtb-killing efficacy in Mtb-infected macrophages. We employed mannose surface decoration to develop mannosylated and PEGylated graphene oxide (GO-PEG-MAN). Such nano-platform exhibited increased uptake by macrophages via mannose receptor-mediated endocytosis in vitro. Interestingly, drug-loaded GO-PEG-MAN was preferentially up-taken by mannose receptor-expressing mucosal CD14+ macrophages isolated from Mtb-infected rhesus macaques than drug-loaded GO-PEG. Consistently, the drug concentration was also significantly higher in macrophages than that in T and B cells expressing no or low mannose receptor, implicating a useful macrophage/mannose receptor-targeted drug-delivery system relevant to the in vivo settings. Concurrently, rifampicin-loaded GO-PEG-MAN (Rif@GO-PEG-MAN) significantly increased rifampicin uptake, inducing long-lasting higher concentration of rifampicin in macrophages. Such innovative Rif@GO-PEG-MAN could readily get into the lysosomes of the Mtb host cells, where rifampicin underwent an accelerated release in acidic lysosomic condition, leading to explosive rifampicin release after cell entry for more effective killing of intracellular Mtb. Most importantly, Rif@GO-PEG-MAN-enhanced intracellular rifampicin delivery and pharmacokinetics significantly increased the efficacy of rifampicin-driven killing of intracellular BCG and Mtb bacilli in infected macrophages both in vitro and ex vivo. Such innovative nanocarrier approach may potentially enhance anti-TB drug efficacy and reduce drug side effects.

Dual-Sensitive Graphene Oxide Loaded with Proapoptotic Peptides and Anticancer Drugs for Cancer Synergetic Therapy.

A dual-sensitive drug delivery system (DDS) based on graphene oxide (GO) which is simultaneously loaded with proapoptotic peptides and anticancer drugs was rationally designed and fabricated for cancer synergetic therapy. Specifically, a kind of cell apoptosis peptide (KLAKLAK)2 (KLA) was anchored on the surface of GO via a disulfide bond to obtain GO-SS-KLA. Then, the aromatic anticancer drug doxorubicin (DOX) was loaded on GO through π-π conjugation and hydrogen bonding interactions. Finally, bovine serum albumin (BSA) was used to coat the GO carrier to obtain a biological medium-stable GO-based DDS, DOX@GO-SS-KLA/BSA. The results show that KLA and DOX can be released responding to the reductive and pH stimulus inside the cells, respectively, and achieve a synergetic therapy for cancer. Moreover, the results of stability studies show that DOX@GO-SS-KLA/BSA could be stably dispersed in water for more than 8 days and in 10% fetal bovine serum for at least 6 days. The constructed DOX@GO-SS-KLA/BSA exhibits great potential as a drug carrier for co-delivery of various therapeutic agents.

Graphene quantum dot assisted translocation of drugs into a cell membrane.

Graphene quantum dots (GQDs) are increasingly being recognized as anti-cancer drug carriers, e.g., doxorubicin delivery, in many experiments. In this work, the structure, thermodynamics and dynamic properties of model drugs (doxorubicin and deoxyadenosine) translocating into a POPC lipid membrane with the assistance of GQDs were investigated via MD simulation and free energy calculation. The simulation results imply that GQD19 can facilitate the permeation of model drugs into the lipid membrane on the nanosecond timescale with less deformation of the cell membrane structure. More importantly, free energy calculations further revealed that the translocation free energy of doxorubicin or deoxyadenosine permeating into the lipid bilayer could be significantly reduced with the assistance of GQD19. Our results suggest that GQDs with appropriate size may assist in the drug delivery process by reducing the translocation free energy permeating into the biomembrane. These results may promote the molecular design and application of GQD-based drug delivery systems.

Polydopamine doped reduced graphene oxide/mesoporous silica nanosheets for chemo-photothermal and enhanced photothermal therapy.

The nanoplatform of synergistic chemo-photothermal therapy has superior advantages on antitumor. It is urgently needed to explore novel nanocarrier for improving photothermal performance in drug delivery process. Herein, we synthesized polydopamine doped mesoporous silica-coated reduced graphene oxide (rGO/MSN/PDA) by simply adding dopamine hydrochloride into the oil-water biphasic reaction system as a multifunctional drug carrier for anticancer treatment, which combines chemotherapy and photothermal therapy. The rGO/MSN/PDA showed nearly twice the photothermal conversion efficiency of mesoporous silica-coated graphene oxide (GO/MSN) due to the reduction of GO and doping with PDA. In addition, the rGO/MSN/PDA showed pH-response DOX release abilities, which means higher release of DOX in tumor cells. The cell experiments in vitro proved that rGO/MSN/PDA with better biocompatibility compare to GO/MSN might offer a promising tool for improving the therapeutic effects of hepatocellular carcinoma cells through synergistic chemo-photothermal therapy.

Encapsulation of graphene quantum dot-crosslinked chitosan by carboxymethylcellulose hydrogel beads as a pH-responsive bio-nanocomposite for the oral delivery agent.

Oral delivery most commonly used due to the non-invasive nature and the fact that avoids patient pain and discomfort in compression with the intravenous administration. Herein, the obtained graphene quantum dots (GQDs) from citric acid were employed as a cross-linker for chitosan (CS). Sodium salicylate (SS) as a model drug was loaded in the prepared graphene quantum dots-crosslinked chitosan hybrid bio-nanocomposite beads (CS-GQD). SS-loaded CS-GQD (CS-GQD/SS) was protected with pH-sensitive biopolymeric carboxymethylcellulose (CMC) hydrogel beads. The CMC encapsulated CS-GQD/SS bio-nanocomposite hydrogel beads (CS-GQD/SS@CMC) were characterized using FT-IR, PL and SEM analysis. For determination of surficial charge of the carrier, pH point of zero charges (pHpzc) was measured. In-vitro drug delivery tests were carried out in simulating the gastrointestinal tract conditions for proving the efficiency of the prepared beads as a controlled oral drug delivery. The synergistic effects of CMC and CS enhanced the stability of drug dosing for a long time with controlling the drug releases in the gastrointestinal tract conditions. The MTT test confirmed that the bio-nanocomposite beads have low toxicity against human colon adenocarcinoma HT29 cells. The obtained results showed that the prepared novel CS-GQD/SS@CMC could potentially be used as a safe carrier for oral drug delivery.

Graphene oxide touches blood: in vivo interactions of bio-coronated 2D materials.

Graphene oxide is the hot topic in biomedical and pharmaceutical research of the current decade. However, its complex interactions with human blood components complicate the transition from the promising in vitro results to clinical settings. Even though graphene oxide is made with the same atoms as our organs, tissues and cells, its bi-dimensional nature causes unique interactions with blood proteins and biological membranes and can lead to severe effects like thrombogenicity and immune cell activation. In this review, we will describe the journey of graphene oxide after injection into the bloodstream, from the initial interactions with plasma proteins to the formation of the "biomolecular corona", and biodistribution. We will consider the link between the chemical properties of graphene oxide (and its functionalized/reduced derivatives), protein binding and in vivo response. We will also summarize data on biodistribution and toxicity in view of the current knowledge of the influence of the biomolecular corona on these processes. Our aim is to shed light on the unsolved problems regarding the graphene oxide corona to build the groundwork for the future development of drug delivery technology.

Usefulness of fish cell lines for the initial characterization of toxicity and cellular fate of graphene-related materials (carbon nanofibers and graphene oxide).

Graphene-related materials (GRMs) are one of the most attractive materials from an application perspective, consequently their release into aquatic environments is highly likely. In the present work, the potential of fish hepatocytes (topminnow fish hepatoma cell line, PLHC-1) and macrophages (carp leukocyte cell line, CLC) to study the toxicity and intracellular fate of helical-ribbon carbon nanofibers (CNFs) and graphene oxide (GO) used in a variety of intermediate industrial products was evaluated, allowing a first ranking of GRMs according to their cytotoxicity. Cells were exposed to a concentration range of 0-200 µg ml-1 of GRMs for 24 and 72 h and cell viability was assessed by measuring mitochondrial activity (AlamarBlue assay), plasma membrane integrity (5-carboxyfluorescein diacetate-acetoxymethyl ester assay) and lysosomal function (neutral red uptake assay). Results showed that both the cell type and the choice of endpoint determined the toxicity of GRMs. In both cell lines, CNFs appeared to have higher toxicity than GO and the highest degree of graphitization in fibers was associated with lower toxicity. Transmission electron microscopy revealed that CNFs were taken up into membrane-bound compartments of PLHC-1 cells in a size-independent manner, whereas in CLC, longer CNFs were encountered free in the cytoplasm and only the shorter CNFs were localized in membrane-surrounded vesicles. GO sheets were present within vesicles as well as free in the cytoplasm of both cell types. These findings contribute to the understanding of the toxicity and behaviour of these GRMs in living systems, therefore aiding in designing safer materials for the environment.

Oxidized graphene nanoparticles as a delivery system for the pro-apoptotic sphingolipid C6 ceramide.

Sphingolipids such as ceramide have attracted much attention as possible anticancer agents due to their potent pro-apoptotic effects. However, due to their extreme hydrophobicity, there is currently no clinically approved delivery method for in vivo use as a therapeutic agent. To this end, we have developed a novel method for loading the short-chain C6 ceramide onto oxidized graphene nanoribbons (O-GNRs) and graphene nanoplatelets (GNPs). Mass spectrometry revealed loading efficiencies of 57% and 51.5% for C6 ceramide onto O-GNRs and GNPs, respectively. The PrestoBlue viability assay revealed that 100 µg/mL of C6 ceramide-loaded O-GNRs and C6 ceramide-loaded GNPs reduced HeLa cell viability by approximately 93% and approximately 76%, respectively, compared to untreated HeLa cells, while equal concentrations of these nanoparticles without C6 ceramide did not significantly reduce HeLa cell viability. We confirmed that this cytotoxicity was apoptotic in nature via capase-3 activity and Hoechst staining. Using live-cell confocal imaging with the fluorescent NBD-ceramide loaded on O-GNRs, we observed robust uptake into HeLa cells within 30 min while NBD-ceramide on its own was uptaken much more rapidly. Transmission electron microscopy confirmed that C6 ceramide-loaded O-GNRs were actually entering cells. Taken together, these data show that O-GNRs are a promising delivery agent for ceramide. To our knowledge, this study is the first to use such a loading method. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 25-37, 2019.

Graphene Oxide Finely Tunes the Bioactivity and Drug Delivery of Mesoporous ZnO Scaffolds.

Mesoporous zinc oxide (ZnO) scaffolds coated with drop-cast graphene oxide (GO) flakes are proposed to be a novel bilayer system featuring bioactivity, biocompatibility, and promising loading/release properties for controlled drug-delivery systems. The high-surface-area ZnO scaffolds show clear apatite deposition, but their particular surface chemistry and topography prevent the formation of a continuous coating, resulting in micrometric crystalline apatite aggregates after 28 days in simulated body fluid (SBF). When gentamicin sulfate (GS) is considered as a model molecule, pure ZnO scaffolds also show functional GS loading efficiency, with fast in vitro release kinetics driven by a simple diffusion mechanism. Strikingly, the bioactivity and GS delivery properties of mesoporous ZnO are efficiently triggered by drop-casting GO flakes atop the mesoporous scaffold surface. The resulting ZnO@GO bilayer scaffolds show the formation of a uniform apatite coating after 28 days in SBF and demonstrate a biocompatible behavior, supporting the culture of SaOS-2 osteoblast-like cells. Moreover, the GO coating also leads to a barrier-layer effect, preventing fast GS release, particularly in the short time range. This barrier effect, coupled with the existence of nanopores within the GO structure, sieves drug molecules from the mesoporous ZnO matrix and allows for a delayed release of the GS molecule. We, thus, demonstrated a new-generation ZnO@GO bilayer system as effective multifunctional and biocompatible scaffold for bone tissue engineering.

Topographical Features of Graphene-Oxide-Functionalized Substrates Modulate Cancer and Healthy Cell Adhesion Based on the Cell Tissue of Origin.

Graphene-derived materials, such as graphene oxide (GO), have been widely explored for biomedical and biological applications, including cancer research. Despite some recent works proving that GO inhibits the migration and invasion of different cancer cells, so far most of these in vitro studies have been conducted using GO sheets dispersed in solution or as a planar film. On the contrary, little is known about cellular activities, such as cell viability, adhesion, and spreading, when cancer cells interface with GO functionalized hydrogel-based surfaces, biomechanically and structurally more similar to the tumor environment. Here, we evaluate the interactions of human breast cancer cells (MDA-MB-231) with alginate (Alg)/GO hydrogel-based substrates, and compare them with a cancer cell line from human osteosarcoma (HOS) and healthy murine fibroblasts (3T3). We observed that GO addition selectively inhibits malignant breast cancer cell adhesion efficiency and spreading area, while promotes HOS and 3T3 adhesive processes. Furthermore, we did not observe the same results over Alg substrates with GO nanosheets dispersed in the medium, without embedment into the Alg. This suggests that cancer (MDA-MB-231 and HOS) and healthy (3T3) cell adhesion efficacy does not depend on the cellular tumoral nature and it is driven by the topographical cues provided by the GO-based substrates, whose physical-mechanical characteristics better mimic those of the cell native tissue. We envision that this study can provide a rational for future design and use of graphene-based nanomaterials for cancer research by deepening the knowledge of graphene-cancer cell specific interactions.

Targeted Graphene Oxide Networks: Cytotoxicity and Synergy with Anticancer Agents.

An effective strategy to inhibit endocytosis in cancer cells is presented where modified net-type graphene oxide (GO) sheets, bound with multiple cell surface receptors, are introduced and synthesized as novel anticancer agents. The results suggest that the binding connects GO sheets with neighboring lipid rafts, neutralizes endocytosis, and causes metabolic deprivation. As a result, tumor cell survival and proliferation are reduced. Live cell confocal microscopy imaging reveals that GO-PEGFA (folate-PEGylated GO) (PEG, polyethylene glycol) is internalized by tumor cells, while GO-PEGRGD (tripeptide Arg-Gly-Asp PEGylated GO) associates with the external cell membrane (not internalized). In vitro exposure of tumor cells to GO-PEGFA or GO-PEGRGD reduces the cell viability by 35%, compared to 50% reduction using methotrexate (100 µM). The combination of modified GO sheets with methotrexate or doxorubicin shows a greater toxicity (80% reduction in cell viability) than the individual agents. The proposed setup demonstrates a significant synergy in limiting tumor cell growth.

Multifunctional graphene-based magnetic nanocarriers for combined hyperthermia and dual stimuli-responsive drug delivery.

The synthesis of hydrophilic graphene-based yolk-shell magnetic nanoparticles functionalized with copolymer pluronic F-127 (GYSMNP@PF127) is herein reported to achieve an efficient multifunctional biomedical system for mild hyperthermia and stimuli-responsive drug delivery. In vitro tests revealed the extraordinary ability of GYSMNP@PF127 to act as smart stimuli-responsive multifunctional nanomedicine platform for cancer therapy, exhibiting (i) an outstanding loading capacity of 91% (w/w, representing 910 µg mg-1) of the chemotherapeutic drug doxorubicin, (ii) a high heating efficiency under an alternating (AC) magnetic field (intrinsic power loss ranging from 2.1-2.7 nHm2 kg-1), and (iii) a dual pH and thermal stimuli-responsive drug controlled release (46% at acidic tumour pH vs 7% at physiological pH) under AC magnetic field, in just 30 min. Additionally, GYSMNP@PF127 presents optimal hydrodynamic diameter (DH = 180 nm) with negative surface charge, high haemocompatibility for blood stream applications and tumour cellular uptake of drug nanocarriers. Due to its physicochemical, magnetic and biocompatibility properties, the developed graphene-based magnetic nanocarrier shows high promise as dual exogenous (AC field)/endogenous (pH) stimuli-responsive actuators for targeted thermo-chemotherapy, combining magnetic hyperthermia and controlled drug release triggered by the abnormal tumour environment. The presented strategy and findings can represent a new way to design and develop highly stable added-value graphene-based nanostructures for the combined treatment of cancer.