Prevent Nanoparticle Aggregation Research Articles

Effect of nanofluid cooling on electrical power of solar panel system in existence of TEG implementing magnetic force

This study investigates the efficacy of applying a Lorentz force to improve the efficiency of a photovoltaic-thermal (PVT) system featuring a finned duct, while also addressing challenges associated with dust accumulation. The magnetic field helps to prevent nanoparticle aggregation, enhancing the cooling process. The use of a finned duct combined with a nanofluid as the cooling medium efficiently dissipates excess heat from the silicon layer. Dust accumulation on the glass layer reduces transmissivity, negatively impacting system performance. The magnetic field's interaction with the nanoparticles enhances convective cooling of the upper layer, leading to an overall improvement in performance. Increased pumping power results in higher cooling rates, with improvements of approximately 3.48 % in thermal efficiency (ηth), 75.01 % in thermoelectric generator efficiency (ηTEG), and 39.37 % in photovoltaic efficiency (ηPV). An increase in the Hartmann number (Ha) improves ηth by about 1.87 %, with corresponding enhancements in electrical performance components. A higher concentration of ferrofluid further boosts performance, with the effect being roughly 1.7 times more significant in the absence of MHD compared to when Ha = 97. Dust presence decreases ηth, ηTEG, and ηPV by approximately 9.39 %, 8.55 %, and 25.77 %, respectively. Furthermore, the presence of Ha diminishes the influence of Vin on ηth by around 1.33 %.

Dye-sensitized sepiolite clay as natural scaffolds for visible light driven photocatalytic hydrogen evolution

Natural clay minerals are increasingly used as superior support materials for various photocatalysts due to their excellent adsorption capacity, negative surface charge, suitable thermal/chemical stability, large specific surface area, and strong surface reactivity, resulting in low agglomeration and suppression of charge recombination. However, they are still insufficient for photocatalysis due to their low efficiency. Therefore, sensitization of clay minerals with dyes to improve the efficiency and specificity of catalysts is considered a promising route for photocatalytic applications. In this work, the effect of dye sensitization on visible light-driven photocatalytic water splitting of microfibrous sepiolite scaffolds as natural photocatalyst supports was investigated for the first time by using various xanthene dyes (eosin Y, rhodamine B and eryhtrosine B (ErB)) and triethanolamine as photosensitizers and sacrificial agents, respectively, in the absence and presence of platinum as a co-catalyst. The clay/dye system was characterized using various techniques such as X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electron microscopy and energy dispersive X-rays. Sep/ErB photocatalysts produced the highest amount of hydrogen among the other Sep/dye scaffold systems because they act as an effective matrix by preventing nanoparticle aggregation and promoting electron transfer due to their excellent crystal structures and physicochemical properties.

A recyclable and durable magnetic cobalt nanoparticle-embedded mesoporous graphene nanohybrid for removal of pollutants from aqueous media

Cobalt nanoparticles (Co NPs) embedded in mesoporous graphene (MG) were prepared via a hydrothermal reaction followed by carbothermal reduction in an argon atmosphere. This cobalt nanoparticle-embedded mesoporous graphene (CoMG) was systematically investigated for structural, morphological, and magnetic properties before and after 10 successive cycles of adsorption and regeneration, using methylene blue (MB) dye as a model pollutant. The CoMG nanohybrid has a superior specific surface area of 807 m2 g−1, with a significant mesopore volume of 1.63 cm3 g−1 that allows fast and high pollutant removal efficiency of ∼84 % within 30 min as well as the maximum adsorption capacity of 178.6 mg g−1 with MB solution of 100 mg L−1, which is well described with pseudo-second-order adsorption kinetics. The consecutive adsorption−regeneration experiments revealed that the CoMG nanohybrid retained more than half of the initial dye removal efficiency even after being reused 10 times. After the tenth cycle, the regenerated CoMG maintained a high specific area of 688 m2 g−1 and a large mesopore volume of 1.51 cm3 g−1, indicating the long-lasting porous structure of the CoMG nanohybrid. The metallic cobalt phase and ferromagnetic nature of the Co NPs in the nanohybrid are retained because of the host MG, which prevents nanoparticle aggregation and serves as a protective environment for the embedded Co NPs in aqueous media during the adsorption−regeneration cycle tests of the adsorbent. The experimental results demonstrate that the CoMG nanohybrid has superior pollutant removal capacity and maintains more than half of the initial efficiency even after 10 cycles of use, making it a cost-efficient and energy-saving material for the removal of organic pollutants from aqueous media and in other environmental applications.

CNTs with nano-confined TiO2 and surface loading Co3O4: The analysis of its performance and mechanism of PMS activation for ECs degradation under visible light

The efficient activation of peroxymonosulfate for degrading emerging contaminants has become a focal point in recent decades, emphasizing the development of novel materials and efficient strategies for high-performance degradation. This study explores a spatial confinement strategy, where TiO2 is confined inside carbon nanotubes with Co3O4 loading outside, is performed to prepare the nano-confined composite TiO2-in-CNT/Co3O4. Norfloxacin is chosen as the primary target pollutant, revealing a degradation rate exceeding 97 % within 30 min. The non-radical 1O2 species were confirmed to be generated in nano-confined catalyst, but not observed in the control non-confined catalyst. Additionally, the quantity of original radical active species significantly increases in nano-confined catalyst compared to non-confined catalyst. TiO2-in-CNT/Co3O4 has excellent reusability and application universality. Wonderful stability is observed in real water and anti-ion interference experiments, highlighting its robust stability. Experimental and DFT calculation results also demonstrate that the spatial confinement strategy prevents nanoparticle aggregation, accelerates electron transfer efficiency, and promotes the cycling of Co2+/Co3+ electron pairs. This work provides insights into the regulation of confined effects in activating PMS and offers a feasible strategy for the synergistic activation of PMS for water environment remediation through a radical and non-radical mixed mechanism.

Fluorine-doped porous carbon coating on Sn/SnOx as anode materials for high-performance potassium ion batteries

Potassium-ion batteries (PIBs) are considered alternatives to lithium-ion batteries because of their comparatively cheaper manufacturing costs and lower potential (2.936 V compared to standard hydrogen electrodes). However, their large ionic radii and unstable structures hindered their satisfactory electrochemical performance. In this study, F–Sn/SnOx@C, a novel porous layered composite material, was prepared using NaCl as a template for in situ etching to obtain a promising negative electrode material for PIBs. The significant specific surface area of the composite material and the uniform embedding of tin nanoparticles within the layered porous carbon shell, contributed to its excellent potassium intercalation/deintercalation performance. Fluorine doping enhanced electron transfer, prevented nanoparticle aggregation, and improved electrolyte penetration and potassium ion migration. The PIBs prepared from this electrode showed high potassium storage capacity, outstanding cycle stability (retaining 263 mAh g−1 after 200 cycles at 100 mA g−1), and remarkable rate capability (505.6, 288.4, 193.5, 134.1, and 83.3 mAh g−1 at 0.1, 0.2, 0.3, 0.5, and 1.0 A g−1, respectively). These results provide a straightforward solution for improving the electrochemical performance of PIBs.

A stable and flexible Au@Ag NPs/PVA SERS platform for thiram residue detection on rough surface

Flexible and transparent surface-enhanced Raman scattering (SERS) substrates have gained great attention in analysis field as they offer a fast, non-destructive, and highly sensitive platform for in-situ detection. In this work, we present a facile one-pot strategy for synthesizing gold-cored silver shell nanoparticles (Au@Ag NPs) in the polyvinyl alcohol (PVA) colloid. With no other reducing agents, PVA can serve as both reducing and stabilizing agents for forming Au@Ag NPs. Besides, PVA acts as a scaffold to maintain SERS “hot-spots” by preventing nanoparticle aggregation. By using this flexible Au@Ag NPs/PVA colloid, the analytes can be extracted from rough surfaces for SERS measurements with excellent sensitivity, repeatability and stability. The SERS activity of the Au@Ag NPs/PVA remained at 89.8% even after 120 days of storage at room temperature in sealed air atmosphere. The selective detection of thiram residues on the surface of fruits and vegetables was successfully achieved. The limits of detection for thiram residues on apple and tomato surfaces were measured to be 0.58 and 0.56 ng cm−2, respectively, with recovery rate ranging from 91% to 107%. This work demonstrates the immense application potential of SERS colloid platform in the fields of food safety and environmental analysis.

Highly Fluorescent ZnO Composite of N-doped Carbon Dots From Dregea Volubilis for Fluorometric Determination of Glucose in Biological Samples.

A nano-sensor based on N-doped carbon dots (NCDs)@ZnO (NCZ) composite was fabricated and efficacy for detecting glucose from human blood and urine samples in a straightforward manner was examined. The composite was prepared following a green hydrothermal method under ambient condition using a novel plant material, Dregea volubilis fruit and structural and optical properties were evaluated using standard techniques. The composite exhibited excellent characteristics including good photostability, biocompatibility, low toxicity, and strong fluorescence, with a decent quantum yield of up to 59%. The NCZ composite has been very sensitive and could selectively detect glucose in urine and blood samples. Selective glucose quenching was efficacious at different concentrations of glucose (1-6mM) and in the pH range of 7-8, limit of detection was 0.25mM. The potential uses of carbon-based materials have grown, thanks to the excellent sensing/detection capabilities of the NCZ composite as well as the capacity to prevent nanoparticle aggregation, opening up new possibilities for the development of environmentally benign nano-sensors.

Well-dispersed NiFe nanoalloy embedded on N-doped carbon nanofibers as free-standing air cathode for all-solid-state flexible zinc-air battery

Flexible zinc-air battery (ZAB) is a viable candidate for energy storage in upcoming flexible-wearable technologies. Non-noble transition metal alloys are used to synthesize oxygen evolution reaction (OER) catalysts to facilitate this development. However, inhibiting self-aggregation and promoting high OER activity in alloy nanoparticles is still challenging. Anchoring metal alloys to carbon support materials may produce a strong metal alloy‑carbon support couple, thereby preventing nanoparticle aggregation. Here, the combination of polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), pyrrole, and Ni/Fe salts resulted in homogeneously NiFe nanoparticles embedded in the free-standing nitrogen-doped‑carbon nanofiber (NiFe-N@CNF), produced via electrospinning and followed by carbonization. The NiFe-N@CNF shows a high OER activity with an overpotential of 351 mV. Importantly, good structural stability of NiFe-N@CNF results in superior OER stability with no voltage change after 14 h of chronopotentiometry stability test. The constructed rechargeable aqueous ZAB with NiFe-N@CNF as the air–cathode displays high peak power density (179 mW cm−2) and high stability up to 500 h. With its flexible properties, free-standing NiFe-N@CNF is also used as all-solid-state ZAB cathode, exhibiting stable performance under both flat and bending conditions, proving the promising application of NiFe-N@CNF for flexible-wearable technologies.

Formation of Protein Nanoparticles in Microdroplet Flow Reactors.

Nanoparticles are increasingly being used for biological applications, such as drug delivery and gene transfection. Different biological and bioinspired building blocks have been used for generating such particles, including lipids and synthetic polymers. Proteins are an attractive class of material for such applications due to their excellent biocompatibility, low immunogenicity, and self-assembly characteristics. Stable, controllable, and homogeneous formation of protein nanoparticles, which is key to successfully delivering cargo intracellularly, has been challenging to achieve using conventional methods. In order to address this issue, we employed droplet microfluidics and utilized the characteristic of rapid and continuous mixing within microdroplets in order to produce highly monodisperse protein nanoparticles. We exploit the naturally occurring vortex flows within microdroplets to prevent nanoparticle aggregation following nucleation, resulting in systematic control over the particle size and monodispersity. Through combination of simulation and experiment, we find that the internal vortex velocity within microdroplets determines the uniformity of the protein nanoparticles, and by varying parameters such as protein concentration and flow rates, we are able to finely tune nanoparticle dimensional properties. Finally, we show that our nanoparticles are highly biocompatible with HEK-293 cells, and through confocal microscopy, we determine that the nanoparticles fully enter into the cell with almost all cells containing them. Due to the high throughput of the method of production and the level of control afforded, we believe that the approach described in this study for generating monodisperse protein-based nanoparticles has the potential for intracellular drug delivery or for gene transfection in the future.

Sintering-free catalytic ammonia cracking by vertically standing 2D porous framework supported Ru nanocatalysts

Catalytic ammonia decomposition enables ammonia to be a hydrogen gas carrier for a carbon-free fuel economy. The challenge is to obtain high conversion yields and rates at low temperatures for a prolonged time. A promising approach is to engineer a catalyst support to minimize deleterious effects like sintering. Here, we compared a conventional 2D planar porous framework support with a vertically standing 2D structure to ascertain the effects of support geometry on the catalytic performance. The catalysts were made by loading ruthenium (Ru) nanoparticles onto the structures, and the catalytic activities were monitored by varying the ammonia (NH3) feeding rate and reaction temperature. Unlike the planar version, the vertically standing 2D support prevented nanoparticle aggregation, retained the original nanoparticle size, and showed an excellent hydrogen production rate (95.17 mmol gRu−1 min−1) at a high flow rate of 32,000 mL gcat−1 h−1 at a temperature of 450 °C.

Robust dual-cross-linked networks enable stable silicon anodes.

The simultaneous attainment of long cycle life and high energy in Si anodes remains challenging. Herein, we introduce the concept of primary building units as organizing units to construct durable and conductive electrode architectures, which helps to facilitate the coalescence of Si nanoparticles with conductive pathways and prevent nanoparticle aggregation.

Facile synthesis of biopolymer decorated magnetic coreshells for enhanced removal of xenobiotic azo dyes through experimental modelling.

Since contamination of xenobiotics in water bodies has become a global issue, their removal is gaining ample attention lately. In the present study, nZVI was synthesized using chitosan for removal of two such xenobitic dyes, Bromocresol green and (BCG) and Brilliant blue (BB), which have high prevalence in freshwater and wastewater matrices. nZVI functionalization prevents nanoparticle aggregation and oxidation, enhancing the removal of BCG and BB with an efficiency of 84.96% and 86.21%, respectively. XRD, FESEM, EDS, and FTIR have been employed to investigate the morphology, elemental composition, and functional groups of chitosan-modified nanoscale-zerovalent iron (CS@nZVI). RSM-CCD model was utilized to assess the combined effect of five independent variables and determine the best condition for maximum dye removal. The interactions between adsorbent dose (2-4 mg), pH (4-8), time (20-40 min), temperature (35-65 0C), and initial dye concentration (40-60 mg/L) was modeled to study the response, i.e., dye removal percentage. The reaction fitted well with Langmuir isotherm and pseudo-first-order kinetics, with a maximum qe value of 426.97 and 452.4mg/g for BCG and BB, respectively. Thermodynamic analysis revealed the adsorption was spontaneous, and endothermic in nature. Moreover, CS@nZVI could be used up to five cycles of dye removal with remarkable potential for real water samples.

Synthesis of iron oxide nanoparticles, characterization, uses as nanozyme and future prospects

Iron oxide nanoparticles (IONPs) have recently attracted wider attention because of their unique properties, such as superparamagnetism, larger surface area, surface-to-volume ratio and simple manufacturing process. Several chemical, physical and biological techniques have been employed to synthesize nanoparticles (NPs) with acceptable surface chemistry. This paper summarizes the approaches for producing IONPs, managing their shape and size and tailoring their properties for bioengineering, pharmaceutical and modern applications. Iron oxides have significant potential in biology, climate change mitigation and horticulture, among several fields. Surface coatings with organic or inorganic particles are one of a kind. The surface coatings of IONPs are critical to their performance because they prevent NP aggregation, reduce the risk of immunogenicity and limit non-specific cellular uptake. Chitosan is a biodegradable polymer that is applied on IONPs to coat them. Chitosan derivatives such as O-(2-hydroxyl)propyl-3-trimethyl ammonium chitosan chloride (O-HTCC; an ammonium quaternary chitosan derivative) have a long-lasting positive charge that allows them to work in different pH ranges, allowing them to interact with cell layers at physiological pH. By reacting epoxypropyltrimethylammonium chloride with chitosan, the hydro-solvent HTCC is formed. For hyperthermic treatment of patients, NPs can also be coordinated to an organ, tissue or tumor through an external attractive field. Given the increasing interest in iron NPs, the purpose of this review is to present data on IONPs, particularly chitosan-capped iron NPs, for different biomedical fields.

Surfactant-Assisted Electrodeposition of Stable Porous Platinum Structures for the Oxygen Reduction Reaction

The demands on the alternative energy sector necessitates high quality research and development to produce economical, reliable and environment friendly energy sources. Proton exchange fuel cells (PEFCs) offer a versatile and dependable alternative to conventional energies both in the transportation and stationary power sectors. Their widespread use is, however, still restricted due to their high cost and the limited availability of platinum (Pt) resources. The high cost of PEFCs is attributed in part to the higher loading of Pt based catalyst at the cathode. The reduction of Pt loadings at the cathode is generally accompanied by significant performance losses due to sluggish oxygen reduction reaction (ORR) kinetics. This issue can be resolved by maximizing the Pt utilization without sacrificing the performance. Hence, on-going research and development work is seeking to better utilize Pt with lower loadings along with optimized performance. Compared to their solid or bulk counterparts, porous structures exhibit a high electrochemical active surface area (A ecsa) and, thus, can enhance the Pt utilization. These porous nanostructures can restructure during fuel cell cycling, and structural collapse can lead to an eventual decrease in Pt utilization.1 Stabilizing agents such as surfactants are usually employed during the Pt nanoparticle (NP) synthesis to prevent NP aggregation. These surfactants can also assist in the formation of the mesoporous structure.2 This study describes the electrochemical deposition of a stable porous Pt structure in the presence of surfactants.A site-directed electrodeposition offers advantages to the wet chemical synthesis of Pt nanocatalysts as it ensures that the Pt is deposited onto specific regions of a support that have a sufficient ionic and electrical conductivity. In this study, we demonstrated the use of anionic, cationic, and non-ionic surfactants to produce porous Pt using electrodeposition and the influence of these surfactants in stabilizing the porous structure during the ORR in acidic medium. The conditions for electrodeposition, such as concentration of surfactants and potential for the nucleation and growth stages were each optimized through a series of experiments. These surfactants included cetyl trimethylammonium bromide (CTAB), sodium dodecylsulfate (SDS), and polyethylene glycol octadecyl ether (Brij 78). We utilized scanning electron microscopy techniques to evaluate the porosity of the deposited NPs and their surface coverage. In these experiments, an initial applied pulse was used to induce nucleation of the Pt followed by the growth of these materials with further electrodeposition at a lower potential. These parameters were evaluated for their influence on the final product, such as the porosity, A ecsa, and the surface coverage these materials.The porosity, composition, and crystallinity of these mesoporous particles were confirmed using transmission electron microscopy (TEM) and selected area electron diffraction techniques. These surfactant systems each resulted in the formation of porous Pt. The porous Pt was also subjected to durability testing by cycling the applied potential over a range of oxidizing potentials. Further analysis of these materials by TEM indicated that the mesoporous structure was maintained after the durability tests with a negligible change in their half-wave potential towards the ORR. The durability testing conducted after the removal of surfactants using Soxhlet extractor confirmed the role of the surfactants in helping to stabilize the porous Pt structure.

Antioxidant colloids via heteroaggregation of cerium oxide nanoparticles and latex beads

Antioxidant colloids were developed via controlled heteroaggregation of cerium oxide nanoparticles (CeO2 NPs) and sulfate-functionalized polystyrene latex (SL) beads. Positively charged CeO2 NPs were directly immobilized onto SL particles of opposite surface charge via electrostatic attraction (SL/Ce composite), while negatively charged CeO2 NPs were initially functionalized with poly(diallyldimethylammonium chloride) (PDADMAC) polyelectrolyte and then, aggregated with the SL particles (SPCe composite). The PDADMAC served to induce a charge reversal on CeO2 NPs, while the SL support prevented nanoparticle aggregation under conditions, where the dispersions of bare CeO2 NPs were unstable. Both SL/Ce and SPCe showed enhanced radical scavenging activity compared to bare CeO2 NPs and were found to mimic peroxidase enzymes. The results demonstrate that SL beads are suitable supports to formulate CeO2 particles and to achieve remarkable dispersion storage stability. The PDADMAC functionalization and immobilization of CeO2 NPs neither compromised the peroxidase-like activity nor the radical scavenging potential. The obtained SL/Ce and SPCe artificial enzymes are foreseen to be excellent antioxidant agents in various applications in the biomedical, food, and cosmetic industries.

New Cysteine-Containing PEG-Glycerolipid Increases the Bloodstream Circulation Time of Upconverting Nanoparticles.

Upconverting nanoparticles have unique spectral and photophysical properties that make them suitable for development of theranostics for imaging and treating large and deep-seated tumors. Nanoparticles based on NaYF4 crystals doped with lanthanides Yb3+ and Er3+ were obtained by the high-temperature decomposition of trifluoroacetates in oleic acid and 1-octadecene. Such particles have pronounced hydrophobic properties. Therefore, to obtain stable dispersions in aqueous media for the study of their properties in vivo and in vitro, the polyethylene glycol (PEG)-glycerolipids of various structures were obtained. To increase the circulation time of PEG-lipid coated nanoparticles in the bloodstream, long-chain substituents are needed to be attached to the glycerol backbone using ether bonds. To prevent nanoparticle aggregation, an L-cysteine-derived negatively charged carboxy group should be included in the lipid molecule.

Eco-Friendly Synthesis of Silver Nanoparticles Using Pulsed Plasma in Liquid: Effect of Surfactants

Silver (Ag) nanoparticles were successfully prepared by using the in-liquid pulsed plasma technique. This method is based on a low voltage, pulsed spark discharge in a dielectric liquid. We explore the effect of the protecting ligands, specifically Cetyl Trimethylammonium Bromide (CTAB), Polyvinylpyrrolidone (PVP), and Sodium n-Dodecyl Sulphate (SDS), used as surfactant materials to prevent nanoparticle aggregation. The X-Ray Diffraction (XRD) patterns of the samples confirm the face-centered cubic crystalline structure of Ag nanoparticles with the presence of Ag2O skin. Scanning Transmission Electron Microscopy (STEM) reveals that spherically shaped Ag nanoparticles with a diameter of 2.2 ± 0.8 nm were synthesised in aqueous solution with PVP surfactant. Similarly, silver nanoparticles with a peak diameter of 1.9 ± 0.4 nm were obtained with SDS surfactant. A broad size distribution was found in the case of CTAB surfactant.

Highly ordered nanoarrays catalysts embedded in carbon nanotubes as highly efficient and robust air electrode for flexible solid-state rechargeable zinc-air batteries

The development of multicomponent materials is the most efficient and successful way for creating advanced multifunctional catalysts. Herein, the bimetal FeCo nanoarrays enclosed N-CNTs have a high surface on carbon cloth support, which promotes efficient electron transport and prevents nanoparticle aggregation. Taking advantage of the high-level use of active material and fast charge transfer, the developed electrocatalyst exhibits excellent multifunctional electrocatalyst such as oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER). The N-CNTs@MOF FeCo nanoarrays @CC exhibit higher activity than reference catalysts including MOF FeCo nanoarrays@CC, FeCo nanoarrays@CC, and CC. Interestingly, the synthesized multifunctional catalyst, which serves as the air electrode in zinc-air batteries with liquid electrolytes as well as solid-state gel electrolytes possesses outstanding charging-discharge performance and long service life. This study provides enormous potential for the real implementation of portable, even wearable, and efficient rechargeable batteries in the future.

Opportunities for Electrocatalytic CO2 Reduction Enabled by Surface Ligands.

To achieve high selectivity in enzyme catalysis, nature carefully controls both the catalyst active site and the pocket or environment that mediates access and the geometry of a reactant. Despite the many advantages of heterogeneous catalysis, active sites on a surface are rarely defined with atomic precision, making it difficult to control reaction selectivity with the molecular precision of homogeneous systems. In colloidal nanoparticle synthesis, structural control is accomplished using a surface ligand or capping layer that stabilizes a specific particle morphology and prevents nanoparticle aggregation. Usually, these surface ligands are considered detrimental for catalysis because they occupy otherwise active surface sites. However, a number of examples have shown that surface ligands can play a beneficial role in defining the catalytic environment and enhancing performance by a variety of mechanisms. This perspective summarizes recent advances and opportunities using surface ligands to enhance the performance of nanocatalysts for electrochemical CO2 reduction. Several mechanisms are discussed, including selective permeability, modulating interfacial solvation structure and electric fields, chemical activation, and templating active site selection. These examples inform strategies and point to emerging opportunities to design nanocatalysts toward molecular level control of electrochemical CO2 conversion.

A novel therapeutic vaccine based on graphene oxide nanocomposite for tumor immunotherapy

With an intensive understanding of the mechanism of immune system, developing a therapeutic tumor vaccine is one of the most perspective strategy of cancer immunotherapy. In this study, we report a facile approach to prepare graphene oxide (GO)-based therapeutic cancer-nanovaccine. The model antigen (ovalbumin, OVA) and adjuvant (CpG ODN), are conjugated with GO-PEI nanosheet through electrostatic interaction. The addition of PEG can improve biocompatibility and prevent nanoparticle aggregation. The prepared GO-based nanovaccine, GO-PEI-OVA-PEG-CpG, exhibits good biocompatibility and low toxicity both in vivo and in vitro. More importantly, it can efficiently induce the maturation of dendritic cells (DCs), the enhancement of antigen cross-presentation ability, and the amplification of cytokine production of immune cells. Impressively, this nanovaccine shows a remarkable therapeutic effect against pre-established B16-OVA-melanoma tumors, which can significantly inhibit tumor growth and prolong the survival time of the OVA-expressed tumor-bearing mice. Moreover, combining GO-PEI-OVA-PEG-CpG with NLG919, an IDO-1 (indoleamine-2,3-dioxygenase) inhibitor which can regulate the tumor microenvironment, displays a synergistic therapeutic effect. These findings indicate the GO-PEI-OVA-PEG-CpG nanovaccine actively induces an antigen-specific antitumor immune response and it combined with NLG919 could achieve better therapeutic outcomes.