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

Two-dimensional biomaterials: material science, biological effect and biomedical engineering applications

To date, nanotechnology has increasingly been identified as a promising and efficient means to address a number of challenges associated with public health. In the past decade, two-dimensional (2D) biomaterials, as a unique nanoplatform with planar topology, have attracted explosive interest in various fields such as biomedicine due to their unique morphology, physicochemical properties and biological effect. Motivated by the progress of graphene in biomedicine, dozens of types of ultrathin 2D biomaterials have found versatile bio-applications, including biosensing, biomedical imaging, delivery of therapeutic agents, cancer theranostics, tissue engineering, as well as others. The effective utilization of 2D biomaterials stems from the in-depth knowledge of structure-property-bioactivity-biosafety-application-performance relationships. A comprehensive summary of 2D biomaterials for biomedicine is still lacking. In this comprehensive review, we aim to concentrate on the state-of-the-art 2D biomaterials with a particular focus on their versatile biomedical applications. In particular, we discuss the design, fabrication and functionalization of 2D biomaterials used for diverse biomedical applications based on the up-to-date progress. Furthermore, the interactions between 2D biomaterials and biological systems on the spatial-temporal scale are highlighted, which will deepen the understanding of the underlying action mechanism of 2D biomaterials aiding their design with improved functionalities. Finally, taking the bench-to-bedside as a focus, we conclude this review by proposing the current crucial issues/challenges and presenting the future development directions to advance the clinical translation of these emerging 2D biomaterials.

Magnetic and GRPR-targeted reduced graphene oxide/doxorubicin nanocomposite for dual-targeted chemo-photothermal cancer therapy

Herein, we design a rGO-based magnetic nanocomposite by decorating rGO with citrate-coated magnetic nanoparticles (CMNP). The magnetic rGO (mrGO) was modified by phospholipid-polyethylene glycol to prepare PEGylated mrGO, for conjugating with gastrin-releasing peptide receptor (GRPR)-binding peptide (mrGOG). The anticancer drug doxorubicin (DOX) was bound to mrGO (mrGOG) by π-π stacking for drug delivery triggered by the low pH value in the endosome. The mrGOG showed enhanced photothermal effect under NIR irradiation, endorsing its role for dual targeted DOX delivery. With efficient DOX release in the endosomal environment and heat generation from light absorption in the NIR range, mrGOG/DOX could be used for combination chemo-photothermal therapy after intracellular uptake by cancer cells. We characterized the physico-chemical as well as biological properties of the synthesized nanocomposites. The mrGOG is stable in biological buffer solution, showing high biocompatibility and minimum hemolytic properties. Using U87 glioblastoma cells, we confirmed the magnetic drug targeting effect in vitro for selective cancer cell killing. The peptide ligand-mediated targeted delivery increases the efficiency of intracellular uptake of both nanocomposite and DOX up to ~3 times due to the over-expressed GRPR on U87 surface, leading to higher cytotoxicity. The increased cytotoxicity using mrGOG over mrGO was shown from a decreased IC₅₀ value (0.70 to 0.48 μg/mL) and an increased cell apoptosis rate (19.8% to 47.1%). The IC₅₀ and apoptosis rate changed further to 0.19 μg/mL and 76.8% in combination with NIR laser irradiation, with the photothermal effect supported from upregulation of heat shock protein HSP70 expression. Using U87 tumor xenograft model created in nude mice, we demonstrated that magnetic guidance after intravenous delivery of mrGOG/DOX could significantly reduce tumor size and prolong animal survival over free DOX and non-magnetic guided groups. Augmented with NIR laser treatment for 5 min, the anti-cancer efficacy significantly improves with elevated cell apoptosis and reduced cell proliferation. Together with safety profiles from hematological as well as major organ histological analysis of treated animals, the mrGOG nanocomposite is an effective nanomaterial for combination chemo-photothermal cancer therapy.

Controlled bimatoprost release from graphene oxide laden contact lenses: In vitro and in vivo studies

Ocular drug delivery using contact lenses may be able to substitute for eye drop therapy. However, issues with hydrophobic drugs (like bimatoprost that is used to treat glaucoma) such as low drug uptake using a simple soaking method into preformed contact lenses and alteration in the swelling and transmittance of lenses restricts the application for drug delivery. This research uses graphene oxide (GO) to control the release of bimatoprost from contact lenses along with improvements in the drug uptake, and lens swelling and transmittance. GO was loaded into silicone hydrogel contact lenses by adding the GO at the same time as lenses were polymerized. These lenses were soaked in bimatoprost. Alternatively contact lenses, either with or without GO, were produced by adding bimatoprost during lens polymerization. GO improved contact lens swelling due to its water binding capacity and lens transmittance due to the molecular dispersion of bimatoprost on the surface of the GO which prevented the local precipitation of the drug. The bimatoprost uptake was not improved in the presence of GO. However, its in vitro release profile was improved. Adding bimatoprost and GO at the same time as lenses were polymerized (DL-GO-BMT) significantly decreased the loss of drug during extraction and sterilization in comparison to contact lenses (DL-BMT) without GO. As the amount of GO was increased, the DL-GO-BMT lenses showed a significant decrease in the burst and cumulative release of bimatoprost. Ocular irritation and histopathology reports demonstrated the safety of GO contact lens. The in vivo pharmacokinetic studies in the rabbit tear fluid showed significant improvement in mean residence time (MRT) and area under the curve (AUC) with DL-GO-0.2 μg-BMT-100 contact lens in comparison to eye drop solution. The study demonstrated that the addition of GO to contact lenses can control the release of bimatoprost as well as improved the lens swelling and transmittance. However, further optimization is needed to modulate the release of drug within the therapeutic level to manage glaucoma.

Deeply Infiltrating iRGD-Graphene Oxide for the Intensive Treatment of Metastatic Tumors through PTT-Mediated Chemosensitization and Strengthened Integrin Targeting-Based Antimigration

A limited infiltration and the subsequent low effective drug concentration result in poor chemotherapeutic outcomes against tumors, and even further promote tumor resistance and metastatic. Herein, iRGD-modified graphene oxide (GO) nanosheets (IPHG) are developed for the intensive treatment of metastatic tumors using focus-specific penetrated delivery together with photothermal therapy-mediated chemosensitization and photothermal therapy-strengthened integrin targeting-based antimigration. In vitro and in vivo data verified the mechanism of the tumor-selective infiltration of IPHG is based on a rigid 2D structure-associated advantage regarding hemodynamics and endothelial contact, followed by iRGD-endowed transendothelial and intratumoral transport. Once IPHG-DOX-penetrated 4T1 tumors are exposed to near-infrared irradiation, hyperthermia stress and photothermal therapy-elevated effective drug concentrations result in chemosensitization and prominent tumor suppression. Meanwhile, the specific binding of iRGD to integrins and photothermal therapy leads to the synergistic perturbation of cytoskeleton remodeling and subsequent impairment of cell motility and metastasis. The tailored design of IPHG validates a promising paradigm for drug delivery to combat tumor resistance and metastasis resulting from poor target access for single chemotherapy.

Carbon-Based Composite Phase Change Materials for Thermal Energy Storage, Transfer, and Conversion

Phase change materials (PCMs) can alleviate concerns over energy to some extent by reversibly storing a tremendous amount of renewable and sustainable thermal energy. However, the low thermal conductivity, low electrical conductivity, and weak photoabsorption of pure PCMs hinder their wider applicability and development. To overcome these deficiencies and improve the utilization efficiency of thermal energy, versatile carbon materials have been increasingly considered as supporting materials to construct shape-stabilized composite PCMs. Despite some carbon-based composite PCMs reviews regarding thermal conductivity enhancement, a comprehensive review of carbon-based composite PCMs does not exist. Herein, a systematic overview of recent carbon-based composite PCMs for thermal storage, transfer, conversion (solar-to-thermal, electro-to-thermal and magnetic-to-thermal), and advanced multifunctional applications, including novel metal organic framework (MOF)-derived carbon materials are provided. The current challenges and future opportunities are also highlighted. The authors hope this review can provide in-depth insights and serve as a useful guide for the targeted design of high-performance carbon-based composite PCMs.

Functionalized graphene oxide as a vehicle for targeted drug delivery and bioimaging applications

Graphene oxide (GO) has attracted tremendous attention as a most promising nanomaterial among the carbon family since it emerged as a polynomial functional tool with rational applications in diverse fields such as biomedical engineering, electrocatalysis, biosensing, energy conversion, and storage devices. Despite having certain limitations due to its irreversible aggregation performance owing largely to the strong van der Waals interactions, efforts have been made to smartly engineer its surface chemistry for realistic multimodal applications. The use of such GO-based engineered devices has increased rapidly in the last few years, principally due to its excellent properties, such as huge surface area, honeycomb-like structure allowing vacant interstitial space to accommodate compounds, sp2 hybridized carbon, improved biocompatibility and cell surface penetration due to electronic interactions. Amongst multifaceted GO dynamics, in this review, attempts are made to discuss the advanced applications of GO or graphene-based materials (GBNs) in the biomedical field involving drug or therapeutic gene delivery, dual drug or drug-gene combination targeting, special delivery of drug cocktails to the brain, stimuli-responsive release of molecular payloads, and Janus-structured smart applications for polar-nonpolar combination drug loading followed by targeting together with smart bioimaging approaches. In addition, the advantages of duel-drug delivery systems are discussed in detail. We also discuss various electronic mechanisms, and detailed surface engineering to meet microcosmic criteria for its utilization, various novel implementations of engineered GO as mentioned above, together with discussions of its inevitable toxicity or disadvantages. We hope that the target audience, belonging to biomedical engineering, pharmaceutical or material science fields, may acquire relevant information from this review which may help them design future studies in this field.

Functionalized Reduced Graphene Oxide as a Versatile Tool for Cancer Therapy

Cancer is one of the deadliest diseases in human history with extremely poor prognosis. Although many traditional therapeutic modalities-such as surgery, chemotherapy, and radiation therapy-have proved to be successful in inhibiting the growth of tumor cells, their side effects may vastly limited the actual benefits and patient acceptance. In this context, a nanomedicine approach for cancer therapy using functionalized nanomaterial has been gaining ground recently. Considering the ability to carry various anticancer drugs and to act as a photothermal agent, the use of carbon-based nanomaterials for cancer therapy has advanced rapidly. Within those nanomaterials, reduced graphene oxide (rGO), a graphene family 2D carbon nanomaterial, emerged as a good candidate for cancer photothermal therapy due to its excellent photothermal conversion in the near infrared range, large specific surface area for drug loading, as well as functional groups for functionalization with molecules such as photosensitizers, siRNA, ligands, etc. By unique design, multifunctional nanosystems could be designed based on rGO, which are endowed with promising temperature/pH-dependent drug/gene delivery abilities for multimodal cancer therapy. This could be further augmented by additional advantages offered by functionalized rGO, such as high biocompatibility, targeted delivery, and enhanced photothermal effects. Herewith, we first provide an overview of the most effective reducing agents for rGO synthesis via chemical reduction. This was followed by in-depth review of application of functionalized rGO in different cancer treatment modalities such as chemotherapy, photothermal therapy and/or photodynamic therapy, gene therapy, chemotherapy/phototherapy, and photothermal/immunotherapy.

Multi-Component Hydrogel Beads Incorporated with Reduced Graphene Oxide for pH-Responsive and Controlled Co-Delivery of Multiple Agents

The development of combination therapy has received great attention in recent years because of its potential to achieve higher therapeutic efficacy than that achieved by mono-drug therapy. Carriers for effective and stimuli-responsive co-delivery of multiple agents, however, are highly deficient at the moment. To address this need, this study reports the generation of multi-component hydrogel beads incorporated with reduced graphene oxide (rGO). The beads are prepared by incorporating doxorubicin (DOX)-loaded gelatine (GL) microbeads into hydrogel beads containing rGO and 5-fluorouracil (5-FU). rGO-containing beads are shown to be more effective in inhibiting the growth of MCF-7 cells via the induction of reactive oxygen species (ROS) generation. In addition, the drug release sustainability of the beads is affected by the pH of the release medium, with the release rate increasing in neutral pH but decreasing in the acidic environment. Our beads warrant further development as carriers for pH-responsive and controlled co-delivery of multiple agents.

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

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

Graphene-Based Helical Micromotors Constructed by "Microscale Liquid Rope-Coil Effect" with Microfluidics

Nature provides diverse inspirations for constructing mobile and functionalized micromachines. For example, artificial helical micro-/nanomotors inspired by bacteria flagella that can be precisely steered for various applications have been constructed by utilizing materials with excellent functions. Graphene-based materials show outstanding properties, and, to date, have not been considered to construct helical micromotors and investigate their potential applications. Here, we propose an interesting "microscale liquid rope-coil effect" strategy to stably and simply fabricate graphene oxide-based helical micromotors (GOFHMs) with high throughput by the capillary microfluidics technique. A range of desirable GOFHMs with different pitch, length, and linear diameter are tailored by smart parameter setting in microfluidic system (flow velocity, concentration, and so on). Afterward, graphene-based helical micromotors (GFHMs) are easily acquired by the reduction of GOFHMs and further drying. Actuated by rotating magnetic field, GFHMs show capability to conduct programmed locomotion in a microchannel. As a proof-of-concept demonstration, GFHMs and Ag modified GFHMs have been successfully applied to water remediation, which exhibits excellent removal efficiency of chemical and biological pollutants. Meanwhile, doxorubicin is modified onto GFHMs for the application of drug delivery. Accordingly, we believe that GFHMs have great potential in a variety of fields by modifying graphene with other nanoparticles or functional molecules.

Conducting Polyetheretherketone Nanocomposites with an Electrophoretically Deposited Bioactive Coating for Bone Tissue Regeneration and Multimodal Therapeutic Applications

The use of polyetheretherketone (PEEK) has grown exponentially in the biomedical field in recent decades because of its outstanding biomechanical properties. However, its lack of bioactivity/osteointegration remains an unresolved issue toward its wide use in orthopedic applications. In this work, graphene nanosheets have been incorporated into PEEK to obtain multifunctional nanocomposites. Because of the formation of an electrical percolation network and the π-π* conjugation between graphene and PEEK, the resulting composites have achieved 12 orders of magnitude enhancement in their electrical conductivity and thereby enabled electrophoretic deposition of a bioactive/antibacterial coating consisting of stearyltrimethylammonium chloride-modified hydroxyapatite. The coated composite implant shows significant boosting of bone marrow mesenchymal stem cell proliferation in vitro. In addition, the strong photothermal conversion effect of the graphene nanofillers has enabled laser-induced heating of our nanocomposite implants, where the temperature of the implant can reach 45 °C in 150 s. The unique multifunctionality of the implant has also been demonstrated for photothermal applications such as enhancing bacterial eradication and tumor cell inhibition, as well as bone tissue regeneration in vivo. The results suggest the strong potential of our multifunctional implant in bone repair applications as well as multimodal therapy of challenging bone diseases such as osteosarcoma and osteomyelitis.

Light: A Magical Tool for Controlled Drug Delivery

Light is a particularly appealing tool for on-demand drug delivery due to its noninvasive nature, ease of application and exquisite temporal and spatial control. Great progress has been achieved in the development of novel light-driven drug delivery strategies with both breadth and depth. Light-controlled drug delivery platforms can be generally categorized into three groups: photochemical, photothermal, and photoisomerization-mediated therapies. Various advanced materials, such as metal nanoparticles, metal sulfides and oxides, metal-organic frameworks, carbon nanomaterials, upconversion nanoparticles, semiconductor nanoparticles, stimuli-responsive micelles, polymer- and liposome-based nanoparticles have been applied for light-stimulated drug delivery. In view of the increasing interest in on-demand targeted drug delivery, we review the development of light-responsive systems with a focus on recent advances, key limitations, and future directions.

A multifunctional dual-shell magnetic nanocomposite with near-infrared light response for synergistic chemo-thermal tumor therapy

The synergistic tumor therapy in single nanoplatform has always been the goal for high efficacy tumor treatment while still remains great challenge. This paper reports a versatile nanotheranostic platform enlisting magnetic iron oxide nanoparticles, polydopamine (PDA), gold nanocages (Au nanocage) and metal organic framework (MOF, MIL101-NH₂ ) in order to achieve synergistic chemothermal tumor therapy both in vitro and in vivo. The prepared magnetic photothermal nanoparticles (MPNPs) exhibit high drug loading capacity (31.34 mg/g), superior photo-thermal capacity (11.5°C enhancement in 180 s), low bio-toxicity, good magnetic resonance with a low dosage of 22 μg/g, as well as high antitumor efficacy in vivo. Such a novel and multifunctional nanoplatform is expected to find promising applications in target tumor synergistic therapy.

Exploring High Aspect Ratio Gold Nanotubes as Cytosolic Agents: Structural Engineering and Uptake into Mesothelioma Cells

The generation of effective and safe nanoagents for biological applications requires their physicochemical characteristics to be tunable, and their cellular interactions to be well characterized. Here, the controlled synthesis is developed for preparing high-aspect ratio gold nanotubes (AuNTs) with tailorable wall thickness, microstructure, composition, and optical characteristics. The modulation of optical properties generates AuNTs with strong near infrared absorption. Surface modification enhances dispersibility of AuNTs in aqueous media and results in low cytotoxicity. The uptake and trafficking of these AuNTs by primary mesothelioma cells demonstrate their accumulation in a perinuclear distribution where they are confined initially in membrane-bound vesicles from which they ultimately escape to the cytosol. This represents the first study of the cellular interactions of high-aspect ratio 1D metal nanomaterials and will facilitate the rational design of plasmonic nanoconstructs as cytosolic nanoagents for potential diagnosis and therapeutic applications.

Efficient Lymph Node-Targeted Delivery of Personalized Cancer Vaccines with Reactive Oxygen Species-Inducing Reduced Graphene Oxide Nanosheets

Therapeutic cancer vaccines require robust cellular immunity for the efficient killing of tumor cells, and recent advances in neoantigen discovery may provide safe and promising targets for cancer vaccines. However, elicitation of T cells with strong antitumor efficacy requires intricate multistep processes that have been difficult to attain with traditional vaccination approaches. Here, a multifunctional nanovaccine platform has been developed for direct delivery of neoantigens and adjuvants to lymph nodes (LNs) and highly efficient induction of neoantigen-specific T cell responses. A PEGylated reduced graphene oxide nanosheet (RGO-PEG, 20-30 nm in diameter) is a highly modular and biodegradable platform for facile preparation of neoantigen vaccines within 2 h. RGO-PEG exhibits rapid, efficient (15-20% ID/g), and sustained (up to 72 h) accumulation in LNs, achieving >100-fold improvement in LN-targeted delivery, compared with soluble vaccines. Moreover, RGO-PEG induces intracellular reactive oxygen species in dendritic cells, guiding antigen processing and presentation to T cells. Importantly, a single injection of RGO-PEG vaccine elicits potent neoantigen-specific T cell responses lasting up to 30 days and eradicates established MC-38 colon carcinoma. Further combination with anti-PD-1 therapy achieved great therapeutic improvements against B16F10 melanoma. RGO-PEG may serve a powerful delivery platform for personalized cancer vaccination.

A Comprehensive Insight Towards Pharmaceutical Aspects of Graphene Nanosheets

Graphene Derivatives (GDs) have captured the interest and imagination of pharmaceutical scientists. This review exclusively provides pharmacokinetics and pharmacodynamics information with a particular focus on biopharmaceuticals. GDs can be used as multipurpose pharmaceutical delivery systems due to their ultra-high surface area, flexibility, and fast mobility of charge carriers. Improved effects, targeted delivery to tissues, controlled release profiles, visualization of biodistribution and clearance, and overcoming drug resistance are examples of the benefits of GDs. This review focuses on the application of GDs for the delivery of biopharmaceuticals. Also, the pharmacokinetic properties and the advantage of using GDs in pharmaceutics will be reviewed to achieve a comprehensive understanding about the GDs in pharmaceutical sciences.

In vivo self-degradable graphene nanomedicine operated by DNAzyme and photo-switch for controlled anticancer therapy

Although graphene oxide (GO) possesses many beneficial functionalities for biomedical usage as itself, modification of GO surface with several polymers or protein is inevitable for in vivo applications; however, such modification limits the degradability of GO due to the steric hindrance. In that context, designing of a surface modified GO carrier that is going to be degraded after its biological function (i.e., drug delivery) is highly desired, especially at complex in vivo level. Herein, we design an unprecedented "catalytic GO nanomedicine" by applying the catalytic DNA, achieving self-degradation of GO in systemic level in the body after the therapy following surface modification. Once the catalytic GO nanomedicines are taken up by mucin1 (MUC1) aptamer-facilitated endocytosis, a photo-switch triggers the release of doxorubicin from the DNA. The single stranded G-quadruplex sequence on the surface of GO forms a quartet structure and becomes DNAzyme by binding with hemin on the GO surface, exhibiting peroxidase effect. Due to the high H₂O₂ concentration in cancer cells, the catalytic GO nanomedicine generates sufficient amount of strong oxidant, hypochlorous acid (HOCl), inducing GO degradation into small fragments for potential clearance. We demonstrate the potential of our catalytic GO nanomedicine for both therapy and degradation at cellular and complex in vivo environment.

Tailoring Iron Oxide Nanoparticles for Efficient Cellular Internalization and Endosomal Escape

Iron oxide nanoparticles (IONs) have been widely explored for biomedical applications due to their high biocompatibility, surface-coating versatility, and superparamagnetic properties. Upon exposure to an external magnetic field, IONs can be precisely directed to a region of interest and serve as exceptional delivery vehicles and cellular markers. However, the design of nanocarriers that achieve an efficient endocytic uptake, escape lysosomal degradation, and perform precise intracellular functions is still a challenge for their application in translational medicine. This review highlights several aspects that mediate the activation of the endosomal pathways, as well as the different properties that govern endosomal escape and nuclear transfection of magnetic IONs. In particular, we review a variety of ION surface modification alternatives that have emerged for facilitating their endocytic uptake and their timely escape from endosomes, with special emphasis on how these can be manipulated for the rational design of cell-penetrating vehicles. Moreover, additional modifications for enhancing nuclear transfection are also included in the design of therapeutic vehicles that must overcome this barrier. Understanding these mechanisms opens new perspectives in the strategic development of vehicles for cell tracking, cell imaging and the targeted intracellular delivery of drugs and gene therapy sequences and vectors.

A review on advances in graphene-derivative/polysaccharide bionanocomposites: Therapeutics, pharmacogenomics and toxicity

Graphene-based bionanocomposites are employed in several ailments, such as cancers and infectious diseases, due to their large surface area (to carry drugs), photothermal properties, and ease of their functionalization (owing to their active groups). Modification of graphene-derivatives with polysaccharides is a promising strategy to decrease their toxicity and improve target ability, which consequently enhances their biotherapeutic efficacy. Herein, functionalization of graphene-based materials with carbohydrate polymers (e.g., chitosan, starch, alginate, hyaluronic acid, and cellulose) are presented. Subsequently, recent advances in graphene nanomaterial/polysaccharide-based bionanocomposites in infection treatment and cancer therapy are comprehensively discussed. Pharmacogenomic and toxicity assessments for these bionanocomposites are also highlighted to provide insight for future optimized and smart investigations and researches.

Near-Infrared Radiation-Based Mild Photohyperthermia Therapy of Non-Melanoma Skin Cancer with PEGylated Reduced Nanographene Oxide

Using a one-step thermal reduction and non-covalent chemical functionalization process, PEGylated reduced nanographene oxide (rGOn-PEG) was produced from nanographene oxide (GOn) and characterized in terms of particle size, dispersion stability, chemistry, and photothermal properties, in view of its use for photothermal therapy (PTT) of non-melanoma skin cancer. GOn infrared spectrum presented more intense bands assigned to oxygen containing functional groups than observed for rGOn-PEG. GOn C/O ratio decreased more than 50% comparing with rGOn-PEG and nitrogen was present in the latter (N at % = 20.6) due to introduction of PEG-NH2. Thermogravimetric analysis allowed estimating the amount of PEG in rGOn-PEG to be of about 56.1%. Simultaneous reduction and PEGylation increased the lateral dimensions from 287 ± 139 nm to 521 ± 397 nm, as observed by transmission electron microscopy and dynamic light scattering. rGOn-PEG exhibited ≈13-fold higher absorbance in the near-infrared radiation (NIR) region, as compared to unmodified GOn. Low power (150 mW cm-2) NIR irradiation using LEDs resulted in rGOn-PEG heating up to 47 °C, which is within the mild PTT temperature range. PEGylation strongly enhanced the dispersibility of rGOn in physiological media (phosphate buffered saline, fetal bovine serum, and cell culture medium) and also improved the biocompatibility of rGOn-PEG, in comparison to GOn (25-250 μg mL-1). After a single NIR LED irradiation treatment of 30 min, a decrease of ≈38% in A-431 cells viability was observed for rGOn-PEG (250 μg mL-1). Together, our results demonstrate the potential of irradiating rGOn-PEG using lower energy, cheaper, smaller, and safer LEDs, as alternative to high power lasers, for NIR mild hyperthermia therapy of cancer, namely non-melanoma skin cancer.

Recent progress of graphene oxide as a potential vaccine carrier and adjuvant

Vaccine is one of the most effective strategies for preventing and controlling infectious diseases and some noninfectious diseases, especially cancers. Adjuvants and carriers have been appropriately added to the vaccine formulation to improve the immunogenicity of the antigen and induce long-lasting immunity. However, there is an urgent need to develop new all-purpose adjuvants because some adjuvants approved for human use have limited functionality. Graphene oxide (GO), widely employed for the delivery of biomolecules, excels in loading and delivering antigen and shows the potentiality of activating the immune system. However, GO aggregates in biological liquid and induces cell death, and it also exhibits poor biosolubility and biocompatibility. To address these limitations, various surface modification protocols have been employed to integrate aqueous compatible substances with GO to effectively improve its biocompatibility. More importantly, these modifications render functionalized-GO with superior properties as both carriers and adjuvants. Herein, the recent progress of physicochemical properties and surface modification strategies of GO for its application as both carriers and adjuvants is reviewed. STATEMENT OF SIGNIFICANCE: Due to its unique physicochemical properties, graphene oxide is widely employed in medicine for purposes of photothermal treatment of cancer, drug delivery, antibacterial therapy, and medical imaging. Our work describes the surface modification of graphene oxide and for the first time summarizes that functionalized graphene oxide serves as a vaccine carrier and shows significant adjuvant activity in activating cellular and humoral immunity. In the future, it is expected to be introduced into vaccine research to improve the efficacy of vaccines.

Comprehensive Review on Graphene Oxide for Use in Drug Delivery System

Motivated by the accomplishment of carbon nanotubes (CNTs), graphene and graphene oxide (GO) has been widely investigated in the previous studies as an innovative medication nanocarrier for the loading of a variety of therapeutics as well as anti-cancer medications, poor dissolvable medications, antibiotics, antibodies, peptides, DNA, RNA and genes. Graphene provides the ultra-high drug-loading efficiency due to the wide surface area. Graphene and graphene oxide have been widely investigated for biomedical applications due to their exceptional qualities: twodimensional planar structure, wide surface area, chemical and mechanical constancy, sublime conductivity and excellent biocompatibility. Due to these unique qualities, GO applications provide advanced drug transports frameworks and transports of a broad range of therapeutics. In this review, we discussed the latest advances and improvements in the uses of graphene and GO for drug transport and nanomedicine. Initially, we have described what is graphene and graphene oxide. After that, we discussed the qualities of GO as a drug carrier, utilization of GO in drug transport applications, targeted drug transport, transport of anticancer medications, chemical control medicine releasee, co-transport of different medications, comparison of GO with CNTs, nano-graphene for drug transport and at last, we have discussed the graphene toxicity. Finally, we draw a conclusion of current expansion and the potential outlook for the future.

Two-Dimensional Theranostic Nanomaterials in Cancer Treatment: State of the Art and Perspectives

As the combination of therapies enhances the performance of biocompatible materials in cancer treatment, theranostic therapies are attracting increasing attention rather than individual approaches. In this review, we describe a variety of two-dimensional (2D) theranostic nanomaterials and their efficacy in ablating tumors. Though many literature reports are available to demonstrate the potential application of 2D nanomaterials, we have reviewed here cancer-treating therapies based on such multifunctional nanomaterials abstracting the content from literature works which explain both the in vitro and in vivo level of applications. In addition, we have included a discussion about the future direction of 2D nanomaterials in the field of theranostic cancer treatment.

Tumor microenvironment and NIR laser dual-responsive release of berberine 9-O-pyrazole alkyl derivative loaded in graphene oxide nanosheets for chemo-photothermal synergetic cancer therapy

A berberine 9-O-pyrazole alkyl derivative, a chemical compound (called B3) previously synthesized by our group, shows anti-cancer activity. However, B3 lacks targeting cytotoxicity to cancer cells, leading to obvious toxic side effects on normal cells. To solve this problem, here, we prepared a drug delivery system, namely, AS1411-GO/B3 for tumor targeting, in which nano-graphene oxide (GO) sheets were employed as the drug carrier, and the aptamer AS1411 was conjugated onto GO for tumor targeting. GO also had a photothermal effect, which helped the release of B3 from GO as well as the thermal cytotoxicity to cells. We found that the release of B3 could respond to acid conditions, indicating that the tumor intracellular environment could promote the release of B3, thus allowing it to perform chemotherapy effects. This system could also release B3 in response to photothermal heating, moreover, combined photothermal therapy and chemotherapy to improve the anticancer activity was achieved. This AS1411-GO/B3 platform with chemo-photothermal synergetic therapy provides a very promising treatment for tumors.

Lipid-Functionalized Graphene Loaded with hMnSOD for Selective Inhibition of Cancer Cells

Combination therapies utilize multiple mechanisms to target cancer cells to minimize cancer cell survival. Graphene provides an ideal platform for combination therapy due to its photothermal properties and high loading capacity for cancer-fighting molecules. Lipid functionalization of graphene extends its potential as a therapeutic platform by improving its biocompatibility and functionality. Previous studies involving graphene demonstrated its usage as a therapeutic vehicle; however, the effect of bare and engineered graphene structures on oxidative stress has not been comprehensively investigated. Because oxidative stress has been linked to cancer progression, it is vital to examine the generation of reactive oxygen species (ROS) in response to therapeutic platforms. This study functionalizes reduced graphene oxide (rGO) with lipids and the antioxidant enzyme human manganese superoxide dismutase (hMnSOD) and presents a detailed characterization of cellular responses to bare and functionalized rGO nanostructures in tumorigenic and nontumorigenic breast cell lines. Each cell type displayed distinct responses depending on whether they were normal, nonmetastatic, or metastatic cells. Bare rGO significantly reduced cell growth and substantially increased ROS production in all cell lines and instigated necrosis in metastatic breast cancer cells. Cell proliferation decreased in cancerous breast cells upon introduction of lipid-rGO, which correlated with peroxidation of lipids coating the rGO. In contrast, lipid-rGO nanostructures had minimal impact on proliferation and lipid peroxidation for normal breast cells. Lipid-rGO nanostructures with bound hMnSOD inhibited the proliferation of metastatic cancer cells while preventing necrosis and avoiding the negative side effects on normal cells associated with chemotherapeutic agents. Together, the results confirm the importance of functionalizing rGO for therapeutic applications and present an additional modality for the usage of graphene to selectively target cancer cells.

Simple Universal Strategy for Quantification of Carboxyl Groups on Carbon Nanomaterials: Carbon Dioxide Vapor Generation Coupled to Microplasma for Optical Emission Spectrometric Detection

The physicochemical properties and applications of carbon nanomaterials are remarkably dependent on the amount of carboxyl group on their surfaces. Unfortunately, it is challenging to determine the carboxyl group on carbon nanomaterials at an ultralow density not only due to the low sensitivities of conventional techniques, but also because there are no matrix-matched certified reference materials available. In this work, a novel strategy comprising coupling carbon dioxide vapor generation to a microplasma optical emission spectrometer was developed for the sensitive and accurate quantification of surface carboxyl groups on carbon nanomaterials. The carboxyl group on multiwall carbon nanotubes (MWCNTs), graphene (G), or its oxide (GO) was converted to carboxylic acid using concentrated hydrochloric acid prior to quantification. The generated carboxylic acid was purified and then reacted with sodium bicarbonate to generate CO₂, which was swept into a miniaturized point discharge optical emission spectrometer (μPD-OES) for the detection of carbon atomic emission lines. Potassium hydrogen phthalate (KHP) served as a calibration standard for quantification of the carboxyl group on G/GO/MWCNTs, thus, overcoming the lack of CRMs. Owing to the high sensitivity of μPD-OES for the detection of CO₂, a limit of detection of 0.1 μmol g^-1 (1 nmol) was obtained for the carboxyl group based on a sample mass of 10 mg G/GO/MWCNTs, superior to that obtained using conventional methods. Moreover, the proposed method not only retains several unique advantages of good accuracy and elimination of the use of complicated, expensive, and high power-consumption instruments, but was also applicable to the quantification of the carboxyl group on other nanomaterials such as carboxylated magnetic microspheres.

NIR/Thermoresponsive Injectable Self-Healing Hydrogels Containing Polydopamine Nanoparticles for Efficient Synergistic Cancer Thermochemotherapy

Injectable and self-healing hydrogels with thermoresponsiveness as smart hydrogels displayed injectability, automatic healing, and phase and volume changes as well. Here, the thermoresponsive self-healing hydrogel was prepared via the formation of dynamic covalent enamine bonds between the amino groups in polyetherimide (PEI) and the acetoacetate groups in the four-armed star-shaped poly(2-(dimethylamino)ethyl methacrylate-co-2-hydroxyethyl methacrylate) modified with tert-butyl acetoacetate (t-BAA), SP(DMAEMA-co-HEMA-AA). After adding polydopamine nanoparticles (PDA NPs), the SP(DMAEMA-co-HEMA-AA)/PEI/PDA-NP nanocomposite hydrogel presented phase change and volume shrinkage under near-infrared (NIR) irradiation. The thermoresponsive nanocomposite hydrogel loaded with the anticancer drug doxorubicin (DOX) could be injected into the 4T1 tumor by intratumoral injection. After NIR laser irradiation, the temperature of the hydrogel increased because of the photothermal effect of PDA NPs inducing local hyperthermia. Because the hydrophilicity-hydrophobicity transition of the hydrogel occurred, DOX molecules were squeezed out from the hydrogel at temperatures higher than its lower critical solution temperature (LCST) and the tumor cells suffered from internal stress from the shrunk hydrogel. The injectable nanocomposite hydrogel not only demonstrated the synergism of highly efficient thermochemotherapy but also showed the function of improving drug utilization and precise treatment to reduce the side effects of drugs.

PEGylated nano-graphene oxide as a nanocarrier for delivering mixed anticancer drugs to improve anticancer activity

Due to their high specific surface area, graphene oxide and graphene oxide-base nanoparticles have great potential both in dual-drug delivery and combination chemotherapy. Herein, we developed cisplatin (Pt) and doxorubicin (DOX) dual-drug-loaded PEGylated nano-graphene oxide (pGO) to facilitate combined chemotherapy in one system. In this study, nano-sized pGO-Pt/DOX ranged around 161.50 nm was fabricated and characterized using zeta-potential, AFM, TEM, Raman, UV-Vis, and FTIR analyses. The drug delivery efficacy of Pt was enhanced through the introduction of pGO, and the final weight ratio of DOX: Pt: pGO was optimized to 0.376: 0.376: 1. In vitro studies revealed that pGO-Pt/DOX nanoparticles could be effectively delivered into tumor cells, in which they induced prominent cell apoptosis and necrosis and exhibited higher growth inhibition than the single drug delivery system or free drugs. The pGO-Pt/DOX induced the most prominent cancer cell apoptosis and necrosis rate with 18.6%, which was observed almost 2 times higher than that of pGO-Pt or pGO-DOX groups. in the apoptosis and necrotic quadrants In vivo data confirmed that the pGO-Pt/DOX dual-drug delivery system attenuated the toxicity of Pt and DOX to normal organs compared to free drugs. The tumor inhibition data, histopathology observations, and immunohistochemical staining confirmed that the dual-drug delivery system presented a better anticancer effect than free drugs. These results clearly indicated that the pGO-Pt/DOX dual-drug delivery system provided the means for combination drug delivery in cancer treatment.

Graphene family nanomaterials for application in cancer combination photothermal therapy

Combining hyperthermia with other therapies holds a great potential for improving cancer treatment. In this approach, the increase in the body temperature can exert a therapeutic effect on cells and/or enhance the effectiveness of anticancer agents. However, the conventional methodologies available to induce hyperthermia cannot confine a high temperature increase to the tumor-site while maintaining healthy tissues unexposed and ensuring minimal invasiveness. To overcome these limitations, combination photothermal therapy (PTT) mediated by graphene family nanomaterials (GFN) has been showing promising results. Such is owed to the ability of GFN to accumulate at the tumor site and convert near infrared light into heat, enabling a hyperthermia with a high spatial-temporal resolution. Furthermore, GFN can also incorporate different therapeutic agents on their structure for delivery purposes to cancer cells. In this way, the combination PTT mediated by GFN can result in an improved therapeutic effect. In this review, the combination of GFN mediated PTT with chemo-, photodynamic-, gene-, radio-, and immuno-therapies is examined. Furthermore, the main parameters that influence these types of combination approaches are also analyzed, with emphasis on the photothermal potential of GFN and on the vascular and cellular effects produced by the temperature increase mediated by GFN.

Self-Polymerized Dopamine-Decorated Au NPs and Coordinated with Fe-MOF as a Dual Binding Sites and Dual Signal-Amplifying Electrochemical Aptasensor for the Detection of CEA

Fabrication of functional electrochemical biosensor is a hot topic; however, precise and sensitive cancer detection in early clinical diagnosis is still a great challenge. Continuous efforts have been devoted to explore functional materials for this issue. In this work, we developed a dual binding sites and dual signal-amplifying electrochemical aptasensor of self-polymerized dopamine-decorated Au and coordinated with Fe-MOF (Au@PDA@Fe-MOF) for the detection of carcinoembryonic antigen (CEA). Remarkably, Au@PDA@Fe-MOF features high sensitivity, multiple active sites, good biocompatibility, and excellent selectivity, which is attributed to abundant -COOH in porous Fe-MOF and unsaturated Fe³⁺ sites on the surface of Fe-MOF as the active binding sites grafting more NH₂-functionalized CEA-specific aptamer and redox PDA and Fe-MOF accelerating the movement of electrons for dual signal amplifying. Meanwhile, the electrochemical aptasensor shows favorable repeatability with 1.82% relative standard deviation (RSD) under five independent aptasensors and strong stability with only 3.3% degradation after 12 days of storage. In addition, the aptasensor has wide CEA detection range from 1 fg mL^-1 to 1 μg mL^-1 with a low detection limit of 0.33 fg mL^-1 (S/N = 3). Furthermore, the aptasensor is feasible for accurate and quantitative detection of CEA in serum samples with RSD below 2.32%. The satisfying results demonstrate promising applications of the CEA aptasensor in practical sample analysis and lay an important foundation for other biomarker detection in early clinical diagnosis.

Generation of tumor spheroids using a droplet-based microfluidic device for photothermal therapy

Despite their simplicity, monolayer cell cultures are not able to accurately predict drug behavior in vivo due to their inability to accurately mimic cell-cell and cell-matrix interactions. In contrast, cell spheroids are able to reproduce these interactions and thus would be a viable tool for testing drug behavior. However, the generation of homogenous and reproducible cell spheroids on a large scale is a labor intensive and slow process compared to monolayer cell cultures. Here, we present a droplet-based microfluidic device for the automated, large-scale generation of homogenous cell spheroids in a uniform manner. Using the microfluidic system, the size of the spheroids can be tuned to between 100 and 130 μm with generation frequencies of 70 Hz. We demonstrated the photothermal therapy (PTT) application of brain tumor spheroids generated by the microfluidic device using a reduced graphene oxide-branched polyethyleneimine-polyethylene glycol (rGO-BPEI-PEG) nanocomposite as the PTT agent. Furthermore, we generated uniformly sized neural stem cell (NSC)-derived neurospheres in the droplet-based microfluidic device. We also confirmed that the neurites were regulated by neurotoxins. Therefore, this droplet-based microfluidic device could be a powerful tool for photothermal therapy and drug screening applications.

Nanocarriers Used Most in Drug Delivery and Drug Release: Nanohydrogel, Chitosan, Graphene, and Solid Lipid

Over the past few years, nanocarriers have become an ideal solution for safe and efficient drug delivery and release. This is mainly due to the extraordinary characteristics that nanomaterials exhibit when compared with their larger scaled forms. A variety of these carriers are more popular due to their high biocompatibility, ensuring greater efficacy especially in cancer treatments. Nanocrystal, liposomal, and micelle designs of these materials as nanocarriers for drug delivery and release have been extensively researched throughout the past 50 years. Successful applications have not only ensured a greater focus on therapeutic development but also created a new solution available in the pharmaceutical market. Herein, a brief review of research studies focused on nanocarrier materials and designs to achieve superior benefits of drugs for disease treatments is presented. Nanohydrogels, chitosan, graphene oxide, and solid lipid nanoparticle nanocarrier designs and applications are selectively given due to the great attention they have gained from being highly biocompatible and easy-to-manipulate nanocarrier options from organic and inorganic nanocarrier materials. Each summary exhibits the progress that has been achieved to date. With greater understanding of the current state in the development process of these nanomaterials, there is a rising chance to provide better treatment to patients, which is a desperate need in pharmaceutical technologies.

Effect of pH-Responsive Charge-Conversional Polymer Coating to Cationic Reduced Graphene Oxide Nanostructures for Tumor Microenvironment-Targeted Drug Delivery Systems

Tumor tissue represents a slightly acidic pH condition compared to normal tissue due to the accumulation of lactic acids via anaerobic metabolism. In this work, pH-responsive charge-conversional polymer (poly(ethylene imine)-poly(l-lysine)-poly(l-glutamic acid), PKE polymer) was employed for endowing charge-conversional property and serum stability to poly(ethylene imine) conjugated reduced graphene oxide-based drug delivery system (PEI-rGO). Zeta-potential value of PEI-rGO coated with PK5E7 polymer (PK5E7(PEI-rGO)) was -10.9 mV at pH 7.4 and converted to 29.2 mV at pH 6.0, showing pH-responsive charge-conversional property. Sharp-edged plate morphology of PEI-rGO was transformed to spherical nanostructures with vague edges by PK5E7 coating. Size of PK5E7(PEI-rGO) was found to be smaller than that of PEI-rGO in the serum condition, showing its increased serum stability. Loaded doxorubicin (DOX) in PK5E7(PEI-rGO) could be released rapidly in lysosomal condition (pH 5.0, 5 mM glutathione). Furthermore, DOX-loaded PK5E7(PEI-rGO) showed enhanced anticancer activity in HeLa and A549 cells in the tumor microenvironment-mimicking condition (pH 6.0, serum), which would be mediated by non-specific cellular interaction with decorated serum proteins. These results indicate that the pH-responsive charge-conversional PKE polymer coating strategy of cationic rGO nanostructures possesses a potential for acidic tumor microenvironment-targeted drug delivery systems.

Multifunctional two-dimensional nanocomposites for photothermal-based combined cancer therapy

Two-dimensional (2D) nanocomposites have been widely used in biomedical applications during the past few years due to their extraordinary physicochemical properties, which has proved their importance in the field of nanomedicine. Benefiting from the excellent optical absorption in the near-infrared window and large specific surface area, many efforts have been devoted to fabricating 2D nanomaterial-based multifunctional nanoplatforms to realize photothermal therapy (PTT)-based or chemotherapy-based synergistic treatment, which exhibits obvious anti-tumor effects and significantly enhances the therapeutic efficiency of cancer compared with monotherapy. In particular, 2D nanocomposites are usually fabricated as intelligent nanoplatforms for stimuli-responsive nanocarriers, whose therapeutic effects could be specifically activated by the tumor microenvironment (TME). In addition, different fluorescent probes and functional inorganic nanomaterials could be absorbed on the surface of 2D nanomaterials to fabricate multifunctional hybrid nanomaterials with satisfactory magnetic, optical, or other properties that are widely used for multimodal imaging-guided cancer therapy. In this review, the latest development of multifunctional 2D nanocomposites for combination therapy is systematically summarized, mainly focusing on PTT-based synergistic cancer therapy, and the other forms and potential forms of synergistic cancer therapy are also simply summarized. Furthermore, the design principles of 2D nanocomposites are particularly emphasized, and the current challenges and future prospects of 2D nanocomposites for cancer theranostics are discussed simultaneously.

Graphene oxide as a 2D platform for complexation and intracellular delivery of siRNA

The development of efficient and safe nucleic acid delivery vectors remains an unmet need holding back translation of gene therapy approaches to the bedside. Graphene oxide (GO) could help bypass such bottlenecks, thanks to its large surface area, versatile chemistry and biocompatibility, which could overall enhance transfection efficiency while abolishing some of the limitations linked to the use of viral vectors. Here, we aimed to assess the capacity of bare GO, without any further surface modification, to complex a short double-stranded nucleic acid of biological relevance (siRNA) and mediate its intracellular delivery. GO formed stable complexes with siRNA at 10 : 1, 20 : 1 and 50 : 1 GO : siRNA mass ratios. Complexation was further corroborated by atomistic molecular dynamics simulations. GO : siRNA complexes were promptly internalized in a primary mouse cell culture, as early as 4 h after exposure. At this time point, intracellular siRNA levels were comparable to those provided by a lipid-based transfection reagent that achieved significant gene silencing. The time-lapse tracking of internalized GO and siRNA evidenced a sharp decrease of intracellular siRNA from 4 to 12 h, while GO was sequestered in large vesicles, which may explain the lack of biological effects (i.e. gene silencing) achieved by GO : siRNA complexes. This study underlines the potential of non-surface modified GO flakes to act as 2D siRNA delivery platforms, without the need for cationic functionalization, but warrants further vector optimization to allow the effective release of the nucleic acid and achieve efficient gene silencing.