Photothermally triggered cytosolic drug delivery via endosome disruption using a functionalized reduced graphene oxide

Ultra-facile and rapid colorimetric detection of Cu2+ with branched polyethylenimine in 100% aqueous solution

An ultra-facile and rapid colorimetric method was explored to detect Cu²⁺ in 100% aqueous solution by using only BPEI.

A core/shell stabilized polysaccharide-based nanoparticle with intracellular environment-sensitive drug delivery for breast cancer therapy

In this work, we developed a novel core/shell chitosan (Cs)/hyaluronan (HA)-based hybrid nanoparticle, i.e. SNX@Cs-SNX/cHA, with good stability in the bloodstream and intracellular environment-sensitive drug delivery for breast cancer therapy.

BSA-modified poly(pyrrole-3-carboxylic acid) nanoparticles as carriers for combined chemo-photothermal therapy

Homogenous poly(pyrrole-3-carboxylic acid) nanoparticles with high near-infrared absorption and abundant functional groups were fabricated using a facile reverse microemulsion method.

Combination of Redox Assembly and Biomimetic Mineralization To Prepare Graphene-Based Composite Cellular Foams for Versatile Catalysis

Graphene-based materials with hierarchical structures and multifunctionality have gained much interest in a variety of applications. Herein, we report a facile, yet universal approach to prepare graphene-based composite cellular foams (GCCFs) through combination of redox assembly and biomimetic mineralization enabled by cationic polymers. Specifically, cationic polymers (e.g., polyethyleneimine, lysozyme, etc.) could not only reduce and simultaneously assemble graphene oxide (GO) into cellular foams but also confer the cellular foams with mineralization-inducing capability, enabling the formation of inorganic nanoparticles (e.g., silica, titania, silver, etc.). The GCCFs show highly porous structure and appropriate structural stability, where nanoparticles are well distributed on the surface of the reduced GO. Through altering polymer/inorganic pairs, a series of GCCFs are synthesized, which exhibit much enhanced catalytic performance in enzyme catalysis, heterogeneous chemical catalysis, and photocatalysis compared to nanoparticulate catalysts.

Differential effects of graphene oxide nanosheets on Candida albicans phagocytosis by murine peritoneal macrophages

Macrophages, as effector cells involved in the innate and adaptive immunity, play a key role in the response to nanomaterials as graphene oxide (GO) and in their cellular uptake. The interactions at the interface of GO nanosheets, macrophages and microbial pathogens need to be assessed to determine the possible impairment of the immune system induced by biomedical treatments with this nanomaterial. Here, we have evaluated by flow cytometry and confocal microscopy the ability of murine peritoneal macrophages to phagocytose the fungal pathogen Candida albicans, alive or heat-killed, after treatment with poly(ethylene glycol-amine)-derivatized GO nanosheets (PEG-GO). After GO treatment, differences in fungal phagocytosis were observed between macrophages that had taken up GO nanosheets (GO⁺ population) and those that had not (GO^- population). GO treatment increased the ingested alive yeasts in GO^- macrophages, whereas phagocytosis diminished in the GO⁺ population. Ingestion of heat-killed yeasts was slightly higher in both GO^- and GO⁺ populations when comparing with control macrophages. For the first time, we show that GO uptake by macrophages modulates its phagocytic capability, affecting differentially the subsequent ingestion of either alive or heat-killed yeasts. Enhanced ingestion of heat-killed yeast by GO-treated macrophages suggests a beneficial role of this nanomaterial for the clearance of dead microorganisms during infection.

Considerations for Safe Innovation: The Case of Graphene

The terms "Safe innovation" and "Safe(r)-by-design" are currently popular in the field of nanotechnology. These terms are used to describe approaches that advocate the consideration of safety aspects already at an early stage of the innovation process of (nano)materials and nanoenabled products. Here, we investigate the possibilities of considering safety aspects during various stages of the innovation process of graphene, outlining what information is already available for assessing potential hazard, exposure, and risks. In addition, we recommend further steps to be taken by various stakeholders to promote the safe production and safe use of graphene.

Light-switchable systems for remotely controlled drug delivery

Light-switchable systems have recently received attention as a new mode of remotely controlled drug delivery. In the past, a multitude of nanomedicine studies have sought to enhance the specificity of drug delivery to target sites by focusing on receptors overexpressed on malignant cells or environmental features of diseases sites. Despite these immense efforts, however, there are few clinically available nanomedicines. We need a paradigm shift in drug delivery. One strategy that may overcome the limitations of pathophysiology-based drug delivery is the use of remotely controlled delivery technology. Unlike pathophysiology-based active drug targeting strategies, light-switchable systems are not affected by the heterogeneity of cells, tissue types, and/or microenvironments. Instead, they are triggered by remote light (i.e., near-infrared) stimuli, which are absorbed by photoresponsive molecules or three-dimensional nanostructures. The sequential conversion of light to heat or reactive oxygen species can activate drug release and allow it to be spatio-temporally controlled. Light-switchable systems have been used to activate endosomal drug escape, modulate the release of chemical and biological drugs, and alter nanoparticle structures to control the release rates of drugs. This review will address the limitations of pathophysiology-based drug delivery systems, the current status of light-based remote-switch systems, and future directions in the application of light-switchable systems for remotely controlled drug delivery.

NIR Light-, Temperature-, pH-, and Redox-Responsive Polymer-Modified Reduced Graphene Oxide/Mesoporous Silica Sandwich-Like Nanocomposites for Controlled Release

Here a novel quadruple-responsive nanocarrier based on reduced graphene oxide/mesoporous silica sandwich-like nanocomposites (rGO@MS) modified by pH- and temperature-responsive poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) with a linker of disulfide was constructed via surface-initiated atom transfer radical polymerization. The polymer chains would be used as gatekeepers to control the release of the loaded cargo molecules under pH, temperature, NIR light and redox stimuli. The cargo molecules (rhodamine B) were demonstrated to release from the polymer-modified nanocomposites triggered by the quadruple-stimuli. It is noted that the release of the loaded rhodamine B from the nanocarriers could be enhanced greatly under the synergistic effect of multiple stimuli. The prepared quadruple-responsive polymer-modified nanocomposites show a bright prospect in the field of smart nanocarriers for controlled release.

Mesoporous polydopamine nanoparticles with co-delivery function for overcoming multidrug resistance via synergistic chemo-photothermal therapy

Theranostic agents for combined chemo-photothermal therapy have attracted intensive interest in the treatment of multi-drug resistance (MDR) in cancer therapy. However, the development of simple theranostic agents as dual hosts for both heat and a high payload of chemotherapeutic agents remains a big challenge. Herein, mesoporous polydopamine nanoparticles (MPDA) were successfully developed with properties of a high payload of DOX (up to 2000 μg mg^-1) and the drug efflux inhibitor TPGS (d-α-tocopheryl polyethylene glycol 1000 succinate), as well as strong near-infrared absorption. Particularly, DOX and TPGS were sequentially loaded in the pore space and on the external particle surface of MPDA via π-π stacking and hydrophobic interactions, resulting in a MPDA-DOX@TPGS complex. The DOX release observably relies on the pH value and glutathione (GSH). Furthermore, it is possible to accelerate the rate of drug release by NIR irradiation. Importantly, the MPDA-DOX@TPGS complex was found to escape from endosomes after cellular uptake and release the loaded drugs into the cytosol. By TPGS mediated MDR reversal, the delivered DOX induced significant cytotoxicity to MCF-7/ADR cells. Besides, MPDA can absorb the NIR light and convert it into fatal heat to kill the cancer cells. As a consequence, the combined therapy in our system yields a synergistic effect with high therapeutic efficacy.

Uptake of label-free graphene oxide by Caco-2 cells is dependent on the cell differentiation status

BACKGROUND

Understanding the interaction of graphene-related materials (GRM) with human cells is a key to the assessment of their potential risks for human health. There is a knowledge gap regarding the potential uptake of GRM by human intestinal cells after unintended ingestion. Therefore the aim of our study was to investigate the interaction of label-free graphene oxide (GO) with the intestinal cell line Caco-2 in vitro and to shed light on the influence of the cell phenotype given by the differentiation status on cellular uptake behaviour.

RESULTS

Internalisation of two label-free GOs with different lateral size and thickness by undifferentiated and differentiated Caco-2 cells was analysed by scanning electron microscopy and transmission electron microscopy. Semi-quantification of cells associated with GRM was performed by flow cytometry. Undifferentiated Caco-2 cells showed significant amounts of cell-associated GRM, whereas differentiated Caco-2 cells exhibited low adhesion of GO sheets. Transmission electron microscopy analysis revealed internalisation of both applied GO (small and large) by undifferentiated Caco-2 cells. Even large GO sheets with lateral dimensions up to 10 µm, were found internalised by undifferentiated cells, presumably by macropinocytosis. In contrast, no GO uptake could be found for differentiated Caco-2 cells exhibiting an enterocyte-like morphology with apical brush border.

CONCLUSIONS

Our results show that the internalisation of GO is highly dependent on the cell differentiation status of human intestinal cells. During differentiation Caco-2 cells undergo intense phenotypic changes which lead to a dramatic decrease in GRM internalisation. The results support the hypothesis that the cell surface topography of differentiated Caco-2 cells given by the brush border leads to low adhesion of GO sheets and sterical hindrance for material uptake. In addition, the mechanical properties of GRM, especially flexibility of the sheets, seem to be an important factor for internalisation of large GO sheets by epithelial cells. Our results highlight the importance of the choice of the in vitro model to enable better in vitro-in vivo translation.

Imaging Laser-Triggered Drug Release from Gold Nanocages with Transient Absorption Lifetime Microscopy

Nanoparticles have shown promise in loading and delivering drugs for targeted therapy. Many progresses have been made in the design, synthesis, and modification of nanoparticles to fulfill such goals. However, realizing targeted intracellular delivery and controlled release of drugs remains challenging, partly because of the lack of reliable tools to detect the drug-releasing process. In this paper, we applied femtosecond laser pulses to trigger the explosion of gold nanocages (AuNCs) and control the intracellular release of loaded aluminum phthalocyanine (AlPcS) molecules for photodynamic therapy (PDT). AuNCs were found to enhance the encapsulation efficiency and suppress the PDT effect of AlPcS molecules until they were released. More importantly, we discovered that the excited-state lifetimes of the AlPcS-AuNC conjugate (∼3 ps) and free AlPcS (∼11 ps) differ significantly, which was utilized to image the released drug molecules using transient absorption lifetime microscopy with the same laser source. This technique extracts information similar to fluorescence lifetime imaging microscopy but is superior in imaging the molecules that hardly fluoresce or are prone to photobleaching. We further combined a dual-phase lock-in detection technique to show the potential of real-time imaging based on the change in transient optical behaviors. Our method may provide a new tool for investigating nanoparticle-assisted drug delivery and release.

Self-assembled nanocomplex between polymerized phenylboronic acid and doxorubicin for efficient tumor-targeted chemotherapy

Since the discovery that nano-scaled particulates can easily be incorporated into tumors via the enhanced permeability and retention (EPR) effect, such nanostructures have been exploited as therapeutic small molecule delivery systems. However, the convoluted synthetic process of conventional nanostructures has impeded their feasibility and reproducibility in clinical applications. Herein, we report an easily prepared formulation of self-assembled nanostructures for systemic delivery of the anti-cancer drug doxorubicin (DOX). Phenylboronic acid (PBA) was grafted onto the polymeric backbone of poly(maleic anhydride). pPBA-DOX nanocomplexes were prepared by simple mixing, on the basis of the strong interaction between the 1,3-diol of DOX and the PBA moiety on pPBA. Three nanocomplexes (1, 2, 4) were designed on the basis of [PBA]:[DOX] molar ratios of 1:1, 2:1, and 4:1, respectively, to investigate the function of the residual PBA moiety as a targeting ligand. An acid-labile drug release profile was observed, owing to the intrinsic properties of the phenylboronic ester. Moreover, the tumor-targeting ability of the nanocomplexes was demonstrated, both in vitro by confocal microscopy and in vivo by fluorescence imaging, to be driven by an inherent property of the residual PBA. Ligand competition assays with free PBA pre-treatment demonstrated the targeting effect of the residual PBA from the nanocomplexes 2 and 4. Finally, the nanocomplexes 2 and 4, compared with the free DOX, exhibited significantly greater anti-cancer effects in vitro and even in vivo. Our pPBA-DOX nanocomplex enables a new paradigm for self-assembled nanostructures with potential biomedical applications.

Synthesis and Characterization of Graphene Oxide-Polystyrene Composite Capsules with Aqueous Cargo via a Water-Oil-Water Multiple Emulsion Templating Route

Graphene oxide/polystyrene (GO/PS) nanocomposite capsules containing a two-compartment cargo have been successfully fabricated using a Pickering emulsion strategy. Highly purified GO sheets with typically micrometer-scale lateral dimensions and amphiphilic characteristics were prepared from the oxidation reaction of graphite with concomitant exfoliation of the graphite structure. These GO sheets were employed as a stabilizer for oil-in-water emulsions where the oil phase comprised toluene or olive oil. The stability and morphology of the emulsions were extensively studied as a function of different parameters including GO concentration, aqueous phase pH, ultrasonication time, effects of added electrolytes and stability to dilution. In selected conditions, the olive oil emulsions showed spontaneous formation of multiple w/o/w emulsions with high stability, whereas toluene formed simple o/w emulsions of lower overall stability. Olive oil emulsions were therefore used to prepare capsules templated from emulsion droplets by surrounding the oil phase with a GO/PS shell. The GO sheets, emulsions and composite capsules were characterized using a variety of physical and spectroscopic techniques in order to unravel the interactions responsible for capsule formation. The ability of the capsules to control the release of a model active agent in the form of a hydrophilic dye was explored, and release kinetics were monitored using UV-visible spectroscopy to obtain rate parameters. The composite capsules showed promising sustained release properties, with release rates 11× lower than the precursor GO-stabilized multiple emulsion droplets.

Enhanced Endosomal Escape by Light-Fueled Liquid-Metal Transformer

Effective endosomal escape remains as the "holy grail" for endocytosis-based intracellular drug delivery. To date, most of the endosomal escape strategies rely on small molecules, cationic polymers, or pore-forming proteins, which are often limited by the systemic toxicity and lack of specificity. We describe here a light-fueled liquid-metal transformer for effective endosomal escape-facilitated cargo delivery via a chemical-mechanical process. The nanoscale transformer can be prepared by a simple approach of sonicating a low-toxicity liquid-metal. When coated with graphene quantum dots (GQDs), the resulting nanospheres demonstrate the ability to absorb and convert photoenergy to drive the simultaneous phase separation and morphological transformation of the inner liquid-metal core. The morphological transformation from nanospheres to hollow nanorods with a remarkable change of aspect ratio can physically disrupt the endosomal membrane to promote endosomal escape of payloads. This metal-based nanotransformer equipped with GQDs provides a new strategy for facilitating effective endosomal escape to achieve spatiotemporally controlled drug delivery with enhanced efficacy.

Smart Nanostructures for Cargo Delivery: Uncaging and Activating by Light

Nanotechnology has begun to play a remarkable role in various fields of science and technology. In biomedical applications, nanoparticles have opened new horizons, especially for biosensing, targeted delivery of therapeutics, and so forth. Among drug delivery systems (DDSs), smart nanocarriers that respond to specific stimuli in their environment represent a growing field. Nanoplatforms that can be activated by an external application of light can be used for a wide variety of photoactivated therapies, especially light-triggered DDSs, relying on photoisomerization, photo-cross-linking/un-cross-linking, photoreduction, and so forth. In addition, light activation has potential in photodynamic therapy, photothermal therapy, radiotherapy, protected delivery of bioactive moieties, anticancer drug delivery systems, and theranostics (i.e., real-time monitoring and tracking combined with a therapeutic action to different diseases sites and organs). Combinations of these approaches can lead to enhanced and synergistic therapies, employing light as a trigger or for activation. Nonlinear light absorption mechanisms such as two-photon absorption and photon upconversion have been employed in the design of light-responsive DDSs. The integration of a light stimulus into dual/multiresponsive nanocarriers can provide spatiotemporal controlled delivery and release of therapeutic agents, targeted and controlled nanosystems, combined delivery of two or more agents, their on-demand release under specific conditions, and so forth. Overall, light-activated nanomedicines and DDSs are expected to provide more effective therapies against serious diseases such as cancers, inflammation, infections, and cardiovascular disease with reduced side effects and will open new doors toward the treatment of patients worldwide.

Biological Uptake, Distribution, and Depuration of Radio-Labeled Graphene in Adult Zebrafish: Effects of Graphene Size and Natural Organic Matter

The exciting commercial application potential of graphene materials may inevitably lead to their increasing release into the environment where they may pose ecological risks. This study focused on using carbon-14-labeled few-layer graphene (FLG) to determine whether the size of graphene plays a role in its uptake, depuration, and biodistribution in adult zebrafish. After 48 h exposure to larger FLG (L-FLG) at 250 μg/L, the amount of graphene in the organism was close to 48 mg/kg fish dry mass, which was more than 170-fold greater than the body burden of those exposed to the same concentration of smaller FLG (S-FLG). The amount of uptake for both L-FLG and S-FLG increased by a factor of 2.5 and 16, respectively, when natural organic matter (NOM) was added in the exposure suspension. While the L-FLG mainly accumulated in the gut of adult zebrafish, the S-FLG was found in both the gut and liver after exposure with or without NOM. Strikingly, the S-FLG was able to pass through the intestinal wall and enter the intestinal epithelial cells and blood. The presence of NOM increased the quantity of S-FLG in these cells. Exposure to L-FLG or S-FLG also had a significantly different impact on the intestinal microbial community structure.

Multifunctional Nanographene Oxide for Targeted Gene-Mediated Thermochemotherapy of Drug-resistant Tumour

Drug resistance remains a major challenge for anticancer treatment, and one of the major mechanisms of drug resistance is the overexpression of drug efflux transporters in cancer. A new approach for defeating drug resistance is the use of a co-delivery strategy that utilizes small interfering RNA (siRNA) to silence the expression of efflux transporters together with a suitable anticancer drug for drug-resistant cells. In this work, multifunctional graphene capable of integrating multiple functions in one system was employed as a novel co-delivery system for siRNA and doxorubicin (Dox), as well as for the controlled release of intracellular pH-triggered and heat-triggered Dox. Additionally, it was used as a synergistic therapy based on the photothermal effect of graphene oxide (GO) under near-infrared (NIR) irradiation and the chemotherapeutic effect of Dox. The nanocomplex exhibited high drug and siRNA loading. Furthermore, the dual delivery of siRNA and Dox by folic acid (FA)-conjugated polyethylenimine-modified PEGylated nanographene (PPG-FA/siRNA/Dox) exhibited a satisfactory gene silencing effect as well as efficient intracellular delivery of Dox. Thus, Dox could access the nucleus and induce greater cytotoxicity compared with siRNA-absent delivery systems. Significantly, under irradiation, the combined treatment showed more synergistic effect for overcoming drug resistance compared with chemotherapy effect alone.

pH-Responsive ZnO Nanocluster for Lung Cancer Chemotherapy

Here, we demonstrated a pH-responsive nanocluster based on ZnO quantum dots (QDs) and investigated its potential in drug delivery with tumor-specific accumulation. The nanoclusters were composed of small single ZnO QDs by cross-linking dicarboxyl-terminated poly(ethylene glycol) (PEG), showing high stability and biocompatibility in physiological fluids. The clustered ZnO QDs were capable of loading a large quantity of doxorubicin (DOX) via complexation and covalent interactions. After cellular uptake, the drug was efficiently released because the carrier was completely dissolved; the metal-drug complex was disassembled in response to decreasing pH in the endosomes within tumor cells. Moreover, the viability of cancer cells was significantly decreased because the ZnO QDs exhibited cytotoxicity postdissolution and preferentially killed cancerous cells compared to normal cells. Furthermore, this pH-responsive PEG-cZnO QDs cluster system may be capable of tumor homing while circulating in the blood via the enhanced permeability and retention (EPR) effect.

Enhanced Photothermal Bactericidal Activity of the Reduced Graphene Oxide Modified by Cationic Water-Soluble Conjugated Polymer

Surface modification of graphene is extremely important for applications. Here, we report a grafting-through method for grafting water-soluble polythiophenes onto reduced graphene oxide (RGO) sheets. As a result of tailoring of the side chains of the polythiophenes, the modified RGO sheets, that is, RGO-g-P3TOPA and RGO-g-P3TOPS, are positively and negatively charged, respectively. The grafted water-soluble polythiophenes provide the modified RGO sheets with good dispersibility in water and high photothermal conversion efficiencies (ca. 88%). Notably, the positively charged RGO-g-P3TOPA exhibits unprecedentedly excellent photothermal bactericidal activity, because the electrostatic attractions between RGO-g-P3TOPA and Escherichia coli (E. coli) bind them together, facilitating direct heat conduction through their interfaces: the minimum concentration of RGO-g-P3TOPA that kills 100% of E. coli is 2.5 μg mL^-1, which is only 1/16th of that required for RGO-g-P3TOPS to exhibit a similar bactericidal activity. The direct heat conduction mechanism is supported by zeta-potential measurements and photothermal heating tests, in which the achieved temperature of the RGO-g-P3TOPA suspension (2.5 μg mL^-1, 32 °C) that kills 100% of E. coli is found to be much lower than the thermoablation threshold of bacteria. Therefore, this research demonstrates a novel and superior method that combines photothermal heating effect and electrostatic attractions to efficiently kill bacteria.

Cathepsin B-degradable, NIR-responsive nanoparticulate platform for target-specific cancer therapy

Stimuli-responsive anticancer formulations can promote drug release and activation within the target tumour, facilitate cellular uptake, as well as improve the therapeutic efficacy of drugs and reduce off-target effects. In the present work, indocyanine green (ICG)-containing polyglutamate (PGA) nanoparticles were developed and characterized. Digestion of nanoparticles with cathepsin B, a matrix metalloproteinase overexpressed in the microenvironment of advanced tumours, decreased particle size and increased ICG cellular uptake. Incorporation of ICG in PGA nanoparticles provided the NIR-absorbing agent with time-dependent altered optical properties in the presence of cathepsin B. Having minimal dark toxicity, the formulation exhibited significant cytotoxicity upon NIR exposure. Combined use of the formulation with saporin, a ribosome-inactivating protein, resulted in synergistically enhanced cytotoxicity attributed to the photo-induced release of saporin from endo/lysosomes. The results suggest that this therapeutic approach can offer significant therapeutic benefit in the treatment of superficial malignancies, such as head and neck tumours.

High efficient anti-cancer drug delivery systems using tea polyphenols reduced and functionalized graphene oxide

Targeted drug delivery is urgently needed for cancer therapy, and green synthesis is important for the biomedical use of drug delivery systems in the human body. In this work, we report two targeted delivery systems for anticancer drugs based on tea polyphenol functionalized and reduced graphene oxide (TPGs). The obtained TPGs demonstrated an efficient doxorubicin loading capacity as high as 3.430 × 106 mg g−1 and 3.932 × 104 mg g−1, and exhibited pH-triggered release. Furthermore, the kinetic models, adsorption isotherms, and possible loading mechanisms were investigated in details. Compared to TPG1 and free doxorubicin, TPG2 is biocompatible to normal cells even at high concentrations and promotes tumor cells death by delivering the doxorubicin mainly to the nuclei. These results were confirmed using cell viability tests and confocal laser microscopy. Moreover, apoptosis tests showed that the mechanism of cancer cell death induced by TPG1 and TPG2 might follow the similar mechanisms. Taken together, these results demonstrate that TPGs provide a multifunctional drug delivery system with a greater loading capacity and pH-sensitive drug release for enhanced cancer therapy. The high drug payload capability and enhanced antitumor efficacy demonstrate that we developed systems are promising for various biomedical applications and cancer therapy.

Facile fabrication of a resveratrol loaded phospholipid@reduced graphene oxide nanoassembly for targeted and near-infrared laser-triggered chemo/photothermal synergistic therapy of cancer in vivo

A resveratrol-loaded phospholipid coated reduced graphene oxide was prepared using a sonication method.

Leveraging Physiology for Precision Drug Delivery

Physiological characteristics of diseases bring about both challenges and opportunities for targeted drug delivery. Various drug delivery platforms have been devised ranging from macro- to micro- and further into the nanoscopic scale in the past decades. Recently, the favorable physicochemical properties of nanomaterials, including long circulation, robust tissue and cell penetration attract broad interest, leading to extensive studies for therapeutic benefits. Accumulated knowledge about the physiological barriers that affect the in vivo fate of nanomedicine has led to more rational guidelines for tailoring the nanocarriers, such as size, shape, charge, and surface ligands. Meanwhile, progresses in material chemistry and molecular pharmaceutics generate a panel of physiological stimuli-responsive modules that are equipped into the formulations to prepare “smart” drug delivery systems. The capability of harnessing physiological traits of diseased tissues to control the accumulation of or drug release from nanomedicine has further improved the controlled drug release profiles with a precise manner. Successful clinical translation of a few nano-formulations has excited the collaborative efforts from the research community, pharmaceutical industry, and the public towards a promising future of smart drug delivery.

In vivo visualization of endogenous miR-21 using hyaluronic acid-coated graphene oxide for targeted cancer therapy

Oncogene-targeted nucleic acid therapy has been spotlighted as a new paradigm for cancer therapeutics. However, in vivo delivery issues and uncertainty of therapeutic antisense drug reactions remain critical hurdles for a successful targeted cancer therapy. In this study, we developed a fluorescence-switchable theranostic nanoplatform using hyaluronic acid (HA)-conjugated graphene oxide (GO), which is capable of both sensing oncogenic miR-21 and inhibiting its tumorigenicity simultaneously. Cy3-labeled antisense miR-21 peptide nucleic acid (PNA) probes loaded onto HA-GO (HGP21) specifically targeted CD44-positive MBA-MB231 cells and showed fluorescence recovery by interacting with endogenous miR-21 in the cytoplasm of the MBA-MB231 cells. Knockdown of endogenous miR-21 by HGP21 led to decreased proliferation and reduced migration of cancer cells, as well as the induction of apoptosis, with enhanced PTEN levels. Interestingly, in vivo fluorescence signals markedly recovered 3 h after the intravenous delivery of HGP21 and displayed signals more than 5-fold higher than those observed in the HGPscr-treated group of tumor-bearing mice. These findings demonstrate the possibility of using the HGP nanoplatform as a cancer theranostic tool in miRNA-targeted therapy.

Glucose-Reduced Graphene Oxide with Excellent Biocompatibility and Photothermal Efficiency as well as Drug Loading

In the present work, we report a facile and rapid green strategy to fabricate functionalized reduced nano-graphene oxide (nrGO) as a cooperative nanotemplate for both photothermal therapy and drug loading. Graphite oxide was firstly oxidated by nitronium ions (NO2 (+)) solution at the aid of microwave heating to obtain nano-GO (nGO) with about 50 nm of diameter, and the nGO was then reduced in pure glucose at 135 °C for 30 min to obtain nrGO with about 40 nm of diameter. The nrGO exhibits excellent biocompatibility including stable dispersibility in cell culture medium and rapid cellular uptake as well as non-cytotoxicity up to 100 μg/mL. Absorption of the nrGO at 808 nm wavelength increased more than 10-folds compared with nGO. Moreover, the nrGO has the ability to load about 317 % (w/w) of doxorubicin (DOX), and the loaded DOX could be effectively released by acid condition and/or glutathione (GSH) and/or heating. Finally, a greater cancer cell death efficacy was observed in nrGO/DOX-treated cells with GSH and heating stimulation respectively or their combination. Collectively, the nrGO developed here is an outstanding cooperative nano-platform for high-efficiency photothermal therapy and controllable drug delivery.

Indocyanine Green Loaded Reduced Graphene Oxide for In Vivo Photoacoustic/Fluorescence Dual-Modality Tumor Imaging

Multimodality imaging based on multifunctional nanocomposites holds great promise to fundamentally augment the capability of biomedical imaging. Specifically, photoacoustic and fluorescence dual-modality imaging is gaining much interest because of their non-invasiveness and the complementary nature of the two modalities in terms of imaging resolution, depth, sensitivity, and speed. Herein, using a green and facile method, we synthesize indocyanine green (ICG) loaded, polyethylene glycol (PEG)ylated, reduced nano-graphene oxide nanocomposite (rNGO-PEG/ICG) as a new type of fluorescence and photoacoustic dual-modality imaging contrast. The nanocomposite is shown to have minimal toxicity and excellent photoacoustic/fluorescence signals both in vitro and in vivo. Compared with free ICG, the nanocomposite is demonstrated to possess greater stability, longer blood circulation time, and superior passive tumor targeting capability. In vivo study shows that the circulation time of rNGO-PEG/ICG in the mouse body can sustain up to 6 h upon intravenous injection; while after 1 day, no obvious accumulation of rNGO-PEG/ICG is found in any major organs except the tumor regions. The demonstrated high fluorescence/photoacoustic dual contrasts, together with its low toxicity and excellent circulation life time, suggest that the synthesized rNGO-PEG/ICG can be a promising candidate for further translational studies on both the early diagnosis and image-guided therapy/surgery of cancer.

Neuropeptide Y Y1 receptor-mediated biodegradable photoluminescent nanobubbles as ultrasound contrast agents for targeted breast cancer imaging

Targeted molecular imaging has attracted great attention in cancer diagnosis and treatment. However, most clinically used ultrasound contrast agents (UCAs) are non-targeted microbubbles seldom used for cancer imaging. Here, we fabricated fluorescent nanobubbles (NBs) by encapsulation of liquid tetradecafluorohexane (C₆F₁₄) within biodegradable photoluminescent polymers (BPLPs) through an emulsion-evaporation process and conjugation of PNBL-NPY ligand for specific targeting of Y₁ receptors overexpressed in breast tumors. The developed PNBL-NPY modified NBs were uniform in size with good dispersibility and photostability, presenting good ultrasound enhancement. Further, in vitro and in vivo results indicated that the fabricated NBs exhibit high affinity and specificity to Y₁ receptor-overexpressing breast cancer cells and tumors with minimal toxicity and damage to organs. Our developed PNBL-NPY-modified NBs are novel targeted UCAs for safe, efficient and specific targeted breast cancer imaging, and may provide a new nanoplatform for early cancer diagnosis and treatment in the future.

Hydrothermal Reduction of Polyethylenimine and Polyethylene Glycol Dual-Functionalized Nanographene Oxide for High-Efficiency Gene Delivery

In this study, a physiologically stable dual-polymer-functionalized reduced nanographene oxide (nrGO) conjugate (PEG-nrGO-PEI, RGPP) with high efficiency of gene delivery is successfully synthesized through mixing PEGylated nanographene oxide (PEG-nGO, GP) and polyethylenimine (PEI, 25 kDa) solution under 80 °C for 2 h. This hydrothermal reduction of GP during PEIylation promotes the nucleophilic reaction between the amino moieties of PEI and the epoxy groups (or carboxylic groups) in GP and then forms C-NH- groups (or NH-CO groups) to covalently connect PEI and GP, which makes the RGPP nanocomposite more stable in physiological environments and has superior gene transfection efficiency compared with the nonhydrothermally reduced PEG-nGO/PEI conjugate (GPP) obtained by mixing GP and PEI under 20 °C for 2 h. Moreover, 808 nm laser irradiation (2 W/cm²) for 25 min increases ∼1.5-fold of gene transfection efficiency for RGPP but does not increase the gene transfection efficiency of GPP. Finally, RGPP is also able to efficiently deliver functional plasmid GFP-Bax (pGFP-Bax), exhibiting ∼43% of transfection efficiency in HepG2 cells. Collectively, the RGPP developed here is a highly efficient nanocarrier for gene delivery, and this work encourages further explorations of developing functionalized reduced nano-GO for high-efficiency gene therapy.

Controlled release and long-term antibacterial activity of reduced graphene oxide/quaternary ammonium salt nanocomposites prepared by non-covalent modification

In order to control the long-term antibacterial property of quaternary ammonium salts, dodecyl dimethyl benzyl ammonium chloride (rGO-1227) and rGO-bromohexadecyl pyridine (rGO-CPB) were self-assembled on surfaces of reduced graphene oxide (rGO) via π-π interactions. The obtained rGO-1227 and rGO-CPB nanocompounds were characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM).The antibacterial activities were evaluated on Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. Both rGO-CPB and rGO-1227 reduced the cytotoxicity of the pure antimicrobial agents and presented strong antimicrobial properties. Especially, CPB could be loaded efficiently on the surface of rGO via π-π conjugate effect, which resulted in a nanocomposite presenting a long-term antibacterial capability due to the more important quantity of free π electrons compared to that of 1227. When comparing the advantages of both prepared nanocomposites, rGO-CPB displayed a better specific-targeting capability and a longer-term antibacterial property.

Recent Advances of Light-Mediated Theranostics

Currently, precision theranostics have been extensively demanded for the effective treatment of various human diseases. Currently, efficient therapy at the targeted disease areas still remains challenging since most available drug molecules lack of selectivity to the pathological sites. Among different approaches, light-mediated therapeutic strategy has recently emerged as a promising and powerful tool to precisely control the activation of therapeutic reagents and imaging probes in vitro and in vivo, mostly attributed to its unique properties including minimally invasive capability and highly spatiotemporal resolution. Although it has achieved initial success, the conventional strategies for light-mediated theranostics are mostly based on the light with short wavelength (e.g., UV or visible light), which may usually suffer from several undesired drawbacks, such as limited tissue penetration depth, unavoidable light absorption/scattering and potential phototoxicity to healthy tissues, etc. Therefore, a near-infrared (NIR) light-mediated approach on the basis of long-wavelength light (700-1000 nm) irradiation, which displays deep-tissue penetration, minimized photo-damage and low autofluoresence in living systems, has been proposed as an inspiring alternative for precisely phototherapeutic applications in the last decades. Despite numerous NIR light-responsive molecules have been currently proposed for clinical applications, several inherent drawbacks, such as troublesome synthetic procedures, low water solubility and limited accumulation abilities in targeted areas, heavily restrict their applications in deep-tissue therapeutic and imaging studies. Thanks to the amazing properties of several nanomaterials with large extinction coefficient in the NIR region, the construction of NIR light responsive nanoplatforms with multifunctions have become promising approaches for deep-seated diseases diagnosis and therapy. In this review, we summarized various light-triggered theranostic strategies and introduced their great advances in biomedical applications in recent years. Moreover, some other promising light-assisted techniques, such as photoacoustic and Cerenkov radiation, were also systemically discussed. Finally, the potential challenges and future perspectives for light-mediated deep-tissue diagnosis and therapeutics were proposed.

Phototriggered Drug Delivery Using Inorganic Nanomaterials

Light has many desirable properties as the stimulus for triggerable drug delivery systems. Inorganic nanomaterials are often key components in transducing light into drug delivery events. The nature of the light and the inorganic materials can affect the efficacy and safety of the drug delivery system.

Functionalized graphene nanocomposites for enhancing photothermal therapy in tumor treatment

Graphene and its derivatives have unique physical and chemical properties that make them promising vehicles for photothermal therapy (PTT)-based cancer treatment. With intrinsic near-infrared (NIR) absorption properties, graphene-based nanomaterials can be used for PTT and other therapeutics, particularly in combination therapy, to provide successful thermal ablation of cancer cells. In the recent years, advances in graphene-based PTT have produced efficient and efficacious tumor inhibition via nanomaterial structural design and different functionalizations of graphene-derived nanocomposites. Graphene-based nanosystems exhibit multifunctional properties that are useful for PTT applications including enhancement of multimodalities, guided imaging, enhanced chemotherapy and low-power efficient PTT for optimum therapeutic efficiency. Therefore, in this review, we address critical issues and future aspects of PTT-based combination therapy.

Stimuli responsive drug delivery systems based on nano-graphene for cancer therapy

Nano-graphene as a class of two-dimensional sp² carbon nanomaterial has attracted tremendous attentions in various fields in the past decade. Utilizing its unique physical and chemical properties, nano-graphene has also shown great promises in the area of biomedicine, for application in biosensing, imaging and therapy. In particular, with all atoms exposed on its surface, nano-graphene exhibits ultra-high surface area available for efficient binding/loading of various biomolecules of interests, and has been widely used as multifunctional nano-carriers for drug and gene delivery. In this review article, we will summarize the recent advances in the development of nano-graphene as stimuli-responsive nano-carriers for drug delivery, as well as the applications of these smart systems for cancer therapy.

Folate-Mediated Targeted Delivery of Combination Chemotherapeutics Loaded Reduced Graphene Oxide for Synergistic Chemo-Photothermal Therapy of Cancers

PURPOSE

Larger surface area for drug incorporation and superior optical activity makes reduced graphene oxide (rGO) a suitable drug carrier for combination chemotherapeutics delivery. And folate receptors are potential mediators for cancer targeted delivery. This study mainly aimed to prepare irinotecan (IRI)- and docetaxel (DOC)-loaded, folate (FA)-conjugated rGO (FA-P407-rGO/ID) for synergistic cancer therapy.

METHODS

FA-P407-rGO/ID was prepared as aqueous dispersion. Characterization was performed using high performance liquid chromatography (HPLC), transmission electron microscopy (TEM), atomic force microscopy (AFM), ultraviolet/visible spectroscopy, fourier transform infrared spectroscopy (FTIR) and drug release. In vitro cellular studies were performed using 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS), fluorescence-activated cell sorting (FACS) and western blot analyses.

RESULTS

Our results revealed successful preparation of stable FA-P407-rGO/ID formulation with enhanced drug release profiles in acidic microenvironment. In vitro cytotoxicity of the formulation on folate receptor-expressing human mammary carcinoma (MCF-7) cells was higher than that when free IRI/DOC combination (ID) was used; such increased cytotoxicity was not observed in folate receptor-negative hepatocellular carcinoma (HepG2) cells. Cellular uptake of FA-P407-rGO/ID in MCF-7 cells was higher than in HepG2 cells. Further, FACS and western blot analysis revealed better apoptotic effects of the formulation in MCF-7 cells than in HepG2 cells, suggesting the important role of folate receptors for targeted chemotherapy delivery to cancer cells. Near infrared irradiation further enhanced the apoptotic effect in cancer cells, resulting from the photothermal effects of rGO.

CONCLUSIONS

Hence, FA-P407-rGO/ID can be considered as a potential formulation for folate-targeted chemo-photothermal therapy in cancer cells.

Stimuli-Regulated Enzymatically Degradable Smart Graphene-Oxide-Polymer Nanocarrier Facilitating Photothermal Gene Delivery

Graphene oxide (GO) has attracted huge interest in the area of biomedical application due to its unique physicochemical properties, but the issue of long-term toxicity in the body remains unclear. Here, the rationally designed GO nanocarriers (ssPEG-PEI-GO) modified with polyethylene glycol (PEG) and branched polyethylenimine (BPEI) via disulfide linkage are described to control the biological activity of GO as a delivery carrier and its degradation in biological systems. The ssPEG-PEI-GO efficiently interacts with plasmid DNA (pDNA) to form a stable nanocomplex by electrostatic interaction. After cellular uptake, ssPEG-PEI-GO/pDNA complex can easily escape from endosomes by photothermal conversion of GO upon near-infrared irradiation and subsequent photothermally induced endosome disruption. After endosomal escape, reducing intracellular environment enables polymer dissociation and rapid gene release and therefore shows enhanced gene transfection efficiency with low toxicity in comparison with non-reducible amide-functionalized GO nanocarriers (amPEG-PEI-GO) and control BPEIs. Besides, dePEGylated GO nanocarrier, owing to its disulfide bond, exhibits higher entrapment by macrophages compared with amide-functionalized one and subsequently degrades in macrophage. The degradation process can be monitored by photoluminescence emitted from degraded GO. These results suggest new directions in the design of biodegradable and multifunctional GO-based nanocarrier for biomedical application.

Somatostatin Receptor-Mediated Tumor-Targeting Nanocarriers Based on Octreotide-PEG Conjugated Nanographene Oxide for Combined Chemo and Photothermal Therapy

Nano-sized in vivo active targeting drug delivery systems have been developed to a high anti-tumor efficacy strategy against certain cancer-cells-specific. Graphene based nanocarriers with unique physical and chemical properties have shown significant potentials in this aspect. Here, octreotide (OCT), an efficient biotarget molecule, is conjugated to PEGylated nanographene oxide (NGO) drug carriers for the first time. The obtained NGO-PEG-OCT complex shows low toxicity and excellent stability in vivo and is able to achieve somatostatin receptor-mediated tumor-specific targeting delivery. Owing to the high loading efficiency and accurate targeting delivery of anti-cancer drug doxorubicin (DOX), our DOX loaded NGO-PEG-OCT complex offers a remarkably improved cancer-cell-specific cellular uptake, chemo-cytotoxicity, and decreased systemic toxicity compared to free DOX or NGO-PEG. More importantly, due to its strong near-infrared absorption, the NGO-PEG-OCT complex further enhances efficient photothermal ablation of tumors, delivering combined chemo and photothermal therapeutic effect against cancer cells.

Reduced graphene oxide: nanotoxicological profile in rats

Background

We have previously demonstrated that reduced graphene oxide (rGO) administered intravenously in rats was detected inside the hippocampus after downregulation of the tight and adherens junction proteins of the blood–brain barrier. While down-regulators of junctional proteins could be useful tools for drug delivery through the paracellular pathway, concerns over toxicity must be investigated before clinical application. Herein, our purpose was to trace whether the rGO inside the hippocampus triggered toxic alterations in this brain region and in target organs (blood, liver and kidney) of rats at various time points (15 min, 1, 3 h and 7 days).

Results

The assessed rGO-treated rats (7 mg/kg) were clinically indistinguishable from controls at all the time points. Hematological, histopathological (neurons and astrocytes markers), biochemical (nephrotoxicity and hepatotoxicity assessment) and genotoxicological based tests showed that systemic rGO single injection seemed to produce minimal toxicological effects at the time points assessed. Relative to control, the only change was a decrease in the blood urea nitrogen level 3 h post-treatment and increases in superoxide dismutase activity 1 h and 7 days post-treatment. While no alteration in leukocyte parameters was detected between control and rGO-treated animals, time-dependent leukocytosis (rGO-1 h versus rGO-3 h) and leukopenia (rGO-3 h versus rGO-7 days) was observed intra-treated groups. Nevertheless, no inflammatory response was induced in serum and hippocampus at any time.

Conclusions

The toxic effects seemed to be peripheral and transitory in the short-term analysis after systemic administration of rGO. The effects were self-limited and non-significant even at 7 days post-rGO administration.

Synthesis, toxicity, biocompatibility, and biomedical applications of graphene and graphene-related materials

Graphene is a two-dimensional atomic crystal, and since its development it has been applied in many novel ways in both research and industry. Graphene possesses unique properties, and it has been used in many applications including sensors, batteries, fuel cells, supercapacitors, transistors, components of high-strength machinery, and display screens in mobile devices. In the past decade, the biomedical applications of graphene have attracted much interest. Graphene has been reported to have antibacterial, antiplatelet, and anticancer activities. Several salient features of graphene make it a potential candidate for biological and biomedical applications. The synthesis, toxicity, biocompatibility, and biomedical applications of graphene are fundamental issues that require thorough investigation in any kind of applications related to human welfare. Therefore, this review addresses the various methods available for the synthesis of graphene, with special reference to biological synthesis, and highlights the biological applications of graphene with a focus on cancer therapy, drug delivery, bio-imaging, and tissue engineering, together with a brief discussion of the challenges and future perspectives of graphene. We hope to provide a comprehensive review of the latest progress in research on graphene, from synthesis to applications.

Synergistic chemotherapy by combined moderate hyperthermia and photochemical internalization

Combination therapies of photochemical internalization (PCI) and moderate hyperthermia (MHT) were investigated in an in vitro system consisting of human and rat glioma spheroids. PCI using the amphiphilic photosensitizer, AlPcS2a and two anti cancer agents BLM or 5-FU were used. Spheroids were irradiated with λ = 670 nm laser light in an incubator at temperatures ranging from 37 to 44°C. For each temperature investigated, spheroids were divided into 4 groups: control, drug-only, photodynamic therapy (PDT), and PCI. PDT and PCI spheroids were exposed to radiant exposures ranging from 0.3 to 2.5 J cm(-2) using an irradiance of 5 mW cm(-2). Toxicity was evaluated from spheroid growth kinetics. The combination of PCI and MHT resulted in significant increases in BLM efficacy at 44°C for both cell line derived spheroids compared to controls at 37°C over the range of radiant exposures examined. 5-FU PCI was ineffective for the human cell line at both 37 and 44°C.