Graphene Oxide Membrane Reactor for Electrochemical Deuteration Reactions.

The deuteration of organic molecules is considerably important in organic and medicinal chemistry. An electrochemical membrane reactor using proton-conducting graphene oxide (GO) nanosheets was developed to synthesize valuable deuterium-labeled products via an efficient hydrogen-to-deuterium (H/D) exchange under mild conditions at ambient temperature and atmospheric pressure. Deuterons (D+) formed by the anodic oxidation of heavy water (D2O) at the Pt/C anode permeate through the GO membrane to the Pt/C cathode, where organic molecules with functional groups (C≡C and C═O) are deuterated with adsorbed atomic D species. Deuteration occurs in outstanding yields with high levels of D incorporation. We also achieved the electrodeuteration of a drug molecule, ibuprofen, demonstrating the promising feasibility of the GO membrane reactor in the pharmaceutical industry.

GO-PEG Represses the Progression of Liver Inflammation via Regulating the M1/M2 Polarization of Kupffer Cells.

As a highly promising nanomaterial, exploring the impact of the liver, a vital organ, stands out as a crucial focus in the examination of its biological effects. Kupffer cells (KCs) are one of the first immune cells to contact with exotic-substances in liver. Therefore, this study investigates the immunomodulatory effects and mechanisms of polyethylene glycol-modified graphene oxide (GO-PEG) on KCs. Initial RNA-seq and KEGG pathway analyses reveal the inhibition of the TOLL-like receptor, TNF-α and NOD-like receptor pathways in continually stimulated KCs exposed to GO-PEG. Subsequent biological experiments validate that a 48-hour exposure to GO-PEG alleviates LPS-induced KCs immune activation, characterized by a shift in polarization from M1 to M2. The underlying mechanism involves the absorption of double-stranded RNA/single-stranded RNA, inhibiting the activation of TLR3 and TLR7 in KCs. Employing a Kupffer/AML12 cell co-culture model and animal studies, it is observed that GO-PEG indirectly inhibit oxidative stress, mitochondrial dysfunction, and apoptosis in AML12 cells, partially mitigating systemic inflammation and preserving liver tissue/function. This effect is attributed to the paracrine interaction between KCs and hepatocytes. These findings suggest a meaningful and effective strategy for treating liver inflammation, particularly when combined with anti-inflammatory drugs.

Enhanced electrochemical performance of NiMn layered double hydroxides/graphene oxide composites synthesized by one-step hydrothermal method for supercapacitors.

This study aims to enhance the performance of supercapacitors, focusing particularly on optimizing electrode materials. While pure NiMn layered double hydroxides (LDHs) exhibit excellent electrochemical properties, they have limitations in achieving high specific capacitance. Therefore, this paper successfully synthesized composite materials of NiMn LDHs with varying loadings of graphene oxide (GO) using a hydrothermal method. Systematic physicochemical characterization of the synthesized materials, such as powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FE-SEM), and Raman spectroscopy, revealed the influence of GO doping on the microstructure and electrochemical performance of NiMn LDHs. Electrochemical tests demonstrated that the NiMn LDHs/GO electrode material exhibited optimal electrochemical performance with a specific capacitance of 2096 F g-1 at 1 A g-1 current density and 1471 F g-1 at 10 A g-1, when GO doping level was 0.45 wt%. Furthermore, after 1000 cycles of stability testing, the material retained 53.3% capacitance at 5 A g-1, indicating good cyclic stability. This study not only provides new directions for research on supercapacitor electrode materials but also offers new strategies for developing low-cost and efficient electrode materials.

CRISPR/Cas13a-triggered entropy-driven amplification for colorimetric and fluorescent dual-mode detection of microRNA.

MicroRNAs (miRNAs) are crucial biomarkers for the early detection and monitoring of disease progression of chronic obstructive pulmonary disease (COPD). Herein, we have devised a method for detecting miRNA using a combination of colorimetric and graphene oxide-based fluorescent techniques. The target miRNA in our design could precisely activate the trans-cleavage activity of the CRISPR-Cas13a system. The activated Cas13a enzyme cuts the "rUrU" section in the P1 probe, generating a nicking site to induce entropy-driven amplification (EDA). One of the available EDA products has the capability to unfold the hairpin probe, thereby initiating the catalytic hairpin assembly, exposing the G-quadruplex structure, facilitating the subsequent color response. The fuel strand labeled with Cy3 successfully established a double-stranded DNA structure with DNA3, and consequently the Cy3 would not be quenched by graphene oxide (GO). The implementation of the dual-mode technique in this method yields greater benefits in terms of improving the precision and consistency of the miRNA measurements. The developed method has the capability to fluorescently measure miRNA-21 levels down to a concentration of 5.8 fM. In addition, the analysis of miRNA targets from clinical samples using this method demonstrates its promising utility in the fields of biomedical research of COPD.

Aptamer-based fluorescent sensor for highly sensitive detection of methamphetamine.

The construction of a fluorescence aptamer sensor was achieved by employing the fundamental principle of fluorescence resonance energy transfer. By employing molecular modeling technologies to identify the binding site, the high-affinity aptamer APT-40nt was derived from the whole sequence and utilized on the graphene oxide (GO) fluorescent platform for the purpose of achieving a highly sensitive detection of methamphetamine (METH). The aptamer tagged with fluorescein (FAM) dye undergoes quenching in the presence of GO due to π-stacking interaction. With the addition of the target, the aptamer that has been tagged was detached from the GO surface, forming a stable complex with METH. This process resulted in fluorescence restoration of the system, and the degree of fluorescence restoration was proportional to METH concentration in the linear range of 1-50 and 50-200 nM. Notably, under optimized conditions, the detection limit of this aptasensor was as low as 0.78 nM, which meets the detection limit requirements of METH detection in saliva and urine in some countries and regions. Moreover, other common illicit drugs and metabolites had minimizing interference with the determination. The established aptasensor, therefore, has been successfully applied to detect METH in saliva and urine samples and exhibited satisfactory recoveries (87%-111%). This aptasensor has the advantages of low detection limit, excellent selectivity, ease of operation, and low cost, providing a promising strategy for on-site detection of METH in saliva and urine.

Influence of photothermal nanomaterials localization within the electrospun membrane structure on purification of saline oily wastewater based on photothermal vacuum membrane distillation.

Today, synergistic combination of special nanomaterials (NMs) and electrospinning technique has emerged as a promising strategy to address both water scarcity and energy concerns through the development of photothermal membranes for wastewater purification and desalination. This work was organized to provide a new perspective on membrane design for photothermal vacuum membrane distillation (PVMD) through optimizing membrane performance by varying the localization of photothermal NMs. Poly(vinylidene fluoride) omniphobic photothermal membranes were prepared by localizing graphene oxide nanosheets (GO NSh) (1) on the surface (0.2 wt%), (2) within the nanofibers structure (10 wt%) or (3) in both positions. Considering the case 1, after 7 min exposure to the 1 sun intensity light, the highest temperature (∼93.5 °C) was recorded, which is assigned to the accessibility of GO NSh upon light exposure. The case 3 yielded to a small reduction in surface temperature (∼90.4 °C) compared to the case 1, indicating no need to localize NMs within the nanofibers structure when they are localized on the surface. The other extreme belonged to the case 2 with the lowest temperature of ∼71.3 °C, which is consistent with the less accessibility of GO NSh during irradiation. It was demonstrated that the accessibility of photothermal NMs plays more pronounced role in the membrane surface temperature compared to the light trapping. However, benefiting from higher surface temperature during PVMD due to enhanced accessibility of photothermal NMs is balanced out by decrease in the permeate flux (case 1: 1.51 kg/m2 h and case 2: 1.83 kg/m2 h) due to blocking some membrane surface pores by the binder. A trend similar to that for flux was also followed by the efficiency. Additionally, no change in rejection was observed for different GO NSh localizations.

Glycol 400 assisted preparation of high contact surface TiO2/GO nanocomposites for photocatalytic degradation rhodamine B.

TiO2/graphene oxide (GO) nanocomposites with high contact interface were prepared with glycol 400 (PEG400) served as dispersant. This nanocomposite exhibits improved photocatalytic efficiency in contrast with the nanocomposite prepared without PEG400. In this work, the photocatalytic performance was investigated by observing the degradation rate of Rhodamine B (RhB). And it is found that the mass ratios of GO in nanocomposites plays an important role. When the mass ratio of GO reached 45%, the photocatalytic performance of the nanocomposites reached the highest, which is ∼72%. Moreover, the photocatalytic mechanism was studied through theoretical calculations, which can be summarized as follows: (1) the presence of GO decreases the band gap of TiO2nanoparticles. (2) GO inhibits the the recombination of photogenerated electron-hole pair. (3) GO improves the adsorption capacity of TiO2nanoparticles for RhB. This work promoted the application of TiO2/GO nanocomposites in wastewater treatment.

Exposure of zebrafish (Danio rerio) to graphene oxide for 6 months suppressed NOD-like receptor-regulated anti-virus signaling pathways.

Environmental exposure to graphene oxide (GO) is likely to happen due to the use and disposal of these materials. Although GO-induced ecological toxicity has been evaluated before by using aquatic models such as zebrafish, previous studies typically focused on the short-term toxicity, whereas this study aimed to investigate the long-term toxicity. To this end, we exposed zebrafish to GO for 6 months, and used RNA-sequencing to reveal the changes of signaling pathways. While GO exposure showed no significant effects on locomotor activities, it induced histological changes in livers. RNA-sequencing data showed that GO altered gene expression profiles, resulting in 82 up-regulated and 275 down-regulated genes, respectively. Through the analysis of gene ontology terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, we found that GO suppressed the signaling pathways related with immune systems. We further verified that GO exposure suppressed the expression of genes involved in anti-virus responses possibly through the inhibition of genes involved in NOD-like receptor signaling pathway. Furthermore, NOD-like receptor-regulated lipid genes were also inhibited, which may consequently lead to decreased lipid staining in fish muscles. We concluded that 6 month-exposure to GO suppressed NOD-like receptor-regulated anti-virus signaling pathways in zebrafish.

Efficient Adsorption and Extraction of Glutathione S-Transferases with Glutathione-Functionalized Graphene Oxide-Polyhedral Oligomeric Silsesquioxane Composite.

Glutathione S-transferases (GSTs) are important type-II detoxification enzymes that protect DNA and proteins from damage and are often used as protein tags for the expression of fusion proteins. In the present work, octa-aminopropyl caged polyhedral oligomeric silsesquioxane (OA-POSS) was prepared via acid-catalyzed hydrolysis of 3-aminopropyltriethoxysilane and polymerized on the surface of graphene oxide (GO) through an amidation reaction. Glutathione (GSH) was then modified to GO-POSS through a Michael addition reaction to obtain a GSH-functionalized GO-POSS composite (GPG). The structure and characteristics of the as-prepared GPG composite were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), thermogravity analysis, and surface charge analysis. The specific binding interactions between glutathione and GST gave GPG favorable adsorption selectivity towards GST, and other proteins did not affect GST adsorption. The adsorption behavior of GST on the GPG composite conformed to the Langmuir isotherm model, and the adsorption capacity of GST was high up to 364.94 mg g-1 under optimal conditions. The GPG-based solid-phase adsorption process was applied to the extraction of GST from a crude enzyme solution of pig liver, and high-purity GST was obtained via SDS-PAGE identification.

Microextraction by packed sorbent of selected pesticides in coffee samples employing ionic liquids supported on graphene nanosheets as extraction phase.

This paper describes the synthesis, characterization, and use of ionic liquids supported on silica, functionalized with graphene oxide through covalent bonding (ILz/Si@GO), as sorbents for microextraction by packed sorbent (MEPS). Seven selected pesticides (diazinon, heptachlor, aldrin, endrin, dieldrin, endosulfan, and methoxychlor), used for the prevention of pests in coffee crops, and endosulfan sulfate-an endosulfan metabolite-were selected for this study as model compounds for evaluating the sorbent performance of the synthesized materials in the MEPS device. The cycles of each of the stages were previously optimized through univariate experiments to carry out the extraction. The ILz/Si@GO phase was compared to other sorbents used in MEPS (GO, DVB-MMA, C4/SiO2, C8/SiO2, ILz/SiO2, and bare silica) and also with graphene functionalized through other methodologies, where ILz/Si@GO showed the best results. The material was characterized using a range of techniques. The selectivity of the sorbent material and its adsorption capacity were evaluated by gas chromatography coupled with tandem mass spectrometry. The precision and accuracy of the method showed a relative standard deviation lower than 10% and recoveries from 35 to 97%. Finally, the proposed method was employed for the determination of pesticide residues in coffee samples.

Intratracheal instillation of graphene oxide decreases anti-virus responses and lipid contents via suppressing Toll-like receptor 3 in mouse livers.

Recent studies revealed a causal relationship between Toll-like receptors (TLRs) and lipid droplet biogenesis. Interestingly, it has been reported before that nanomaterials (NMs) were capable to modulate TLRs, but it remains unclear if NMs could affect lipid levels via TLR signaling pathways. In this study, we investigated the influences of airway exposure to graphene oxide (GO) on TLR3 signaling pathways and lipid levels in mouse livers. Intratracheal instillation of GO (0.1, 1, and 5 mg/kg, once a day, totally 5 days) induced inflammatory cell infiltrations as indicated by hematoxylin-eosin (H&E) staining and fibrosis as indicated by Masson staining in lungs, accompanying with decreased TLR3 proteins. Consistently, a TLR3-regulated anti-virus protein, namely interferon induced protein with tetratricopeptide repeats 1 (IFIT1), as well as two TLR3-regulated lipid proteins, namely radical S-adenosyl methionine domain containing 2 (RSAD2) and perilipin 2 (PLIN2), were decreased in lungs. The protein levels of interferon-ß in serum were also decreased. In livers, GO exposure induced disorganization of liver cells but not fibrosis. In agreement with the trends observed in lungs, TLR3, IFIT1, RSAD2, and PLIN2 proteins were decreased in livers. As a possible consequence, GO exposure dose-dependently decreased lipid levels in livers as indicated by oil red O and BODIPY 493/503 staining. We concluded that airway exposure to GO decreased anti-virus responses and lipid levels in mouse livers via the suppression of TLR3.

Sublethal toxicity of graphene oxide in Caenorhabditis elegans under multi-generational exposure.

Nanomaterials have received increasing attentions owing to their potential hazards to the environment and human health; however, the multi-generational toxicity of graphene oxide under consecutive multi-generational exposure scenario still remains unclear. In the present study, Caenorhabditis elegans as an in vivo model organism was employed to explore the multi-generational toxicity effects of graphene oxide and the underlying mechanisms. Endpoints including development and lifespan, locomotion behaviors, defecation cycle, brood sizes, and oxidative response were evaluated in the parental generation and subsequent five filial generations. After continuous exposure for several generations, worms grew smaller and lived shorter. The locomotion behaviors were reduced across the filial generations and these reduced trends were following the impairments of locomotion-related neurons. In addition, the extended defecation cycles from the third filial generation were in consistency with the relative size reduction of the defecation related neuron. Simultaneously, the fertility function of the nematode was impaired under consecutive exposure as reduced brood sizes and oocytes numbers, increased apoptosis of germline, and aberrant expression of reproductive related genes ced-3, ced-4, ced-9, egl-1 and ced-13 were detected in exposed worms. Furthermore, the antioxidant enzyme, SOD-3 was significantly increased in the parent and filial generations. Thus, continuous multi-generational exposure to graphene oxide caused damage to the neuron development and the reproductive system in nematodes. These toxic effects could be reflected by indicators such as growth inhibition, shortened lifespan, and locomotion behavior impairment and induced oxidative response.

Nanoscale Characterization of Graphene Oxide-Based Epoxy Nanocomposite Using Inverted Scanning Microwave Microscopy.

Scanning microwave microscopy (SMM) is a novel metrological tool that advances the quantitative, nanometric, high-frequency, electrical characterization of a broad range of materials of technological importance. In this work, we report an inverted near-field scanning microwave microscopy (iSMM) investigation of a graphene oxide-based epoxy nanocomposite material at a nanoscopic level. The high-resolution spatial mapping of local conductance provides a quantitative analysis of the sample's electrical properties. In particular, the electrical conductivity in the order of ∼10-1 S/m as well as the mapping of the dielectric constant with a value of ∼4.7 ± 0.2 are reported and validated by the full-wave electromagnetic modeling of the tip-sample interaction.

In situcontrol of graphene oxide dispersions with a small impedance sensor.

Carbon-based nanomaterials (CBNs), such as graphene and carbon nanotubes, display advanced physical and chemical properties, which has led to their widespread applications. One of these applications includes the incorporation of CBNs into cementitious materials in the form of aqueous dispersions. The main issue that arises in this context is that currently no established protocol exists as far as characterizing the dispersions. In the present article, an innovative method for quick evaluation and quantification of graphene oxide (GO) dispersions is proposed. The proposed method is electrical impedance spectroscopy (EIS) with an impedance sensor. The novelty lies on the exploitation of a small sensor for on-site (field) direct dielectric measurements with the application of alternating current. Five different concentrations of GO dispersions were studied by applying EIS and for various accumulated ultrasonic energies. The low GO concentration leads to high impedance values due to low formed current network. Two opposing mechanisms were revealed during the accumulation of ultrasonic energy, that are taking place simultaneously: breakage of the agglomerates that facilitates the flow of the electric current due to the formation of a better dispersed network, nevertheless the surface hydrophilic structure of the GO is damaged with the high accumulated ultrasonic energy. The dielectric measurements were exploited to express an appropriate quantitative 'quality index' to facilitate with the dispersion control of the nanostructures. An intermediate concentration of GO is suggested (about 0.15 wt% of the binder materials) to be optimal for the specific engineering application, ultrasonicated at approximately 30 to 65 kJ. The investigated methodology is highly novel and displays a high potential to be applied in-field applications where CBNs must be incorporated in building materials.

Stereolithography (SLA) 3D printing of carbon fiber-graphene oxide (CF-GO) reinforced polymer lattices.

Insufficient mechanical properties of stereolithography (SLA)-printed architected polymer metamaterial limits its wide applications such as in the areas of biomedicine and aerospace. One effective solution is to reinforce the structures with micro- or nano- fibers/particles, but their interfaces are critical for the reinforcement. In this work, a carbon fiber-graphene oxide (CF-GO) polymer composite resin and a mild annealing postprocess have been rationally designed and applied into the manufacturing of oct-truss (OCT) lattices.In situcarbon fiber pulling-out experiment was conducted to exhibit the improve effect of GO on the crosslink of the CF and the polymer matrix interface. We found that the maximum reinforcement was realized when the CF-GO (CF: GO is about 3: 1) content is about 0.8 wt%, followed with annealing. Compared with pure polymer lattices, the compression strength of the CF-GO polymer OCT lattices has been significantly increased from ∼0.22 to ∼2.4 MPa, almost 10 times enhancement. Importantly, the compression strength of the CF-GO polymer OCT lattice (3.08 MPa) further increased by ∼30% after optimized annealing. This work suggests an efficient reinforce strategy for SLA-printed metamaterials, and thus can be valuable for advancing various practical applications of mechanical metamaterials.

A green and facile approach to a graphene-based peroxidase-like nanozyme and its application in sensitive colorimetric detection of L-cysteine.

A facile and green approach to the preparation of peroxidase-like nanozymes by reducing and functionalizing graphene oxide (rGO) with Ganoderma polysaccharide (GP) has been achieved in this work. Our results showed that the as-fabricated nanozyme, namely rGO-GP, possessed the excellent property of simulating peroxidase with higher catalytic activity compared with GO or rGO obtained by using chitosan, which may be due to the better dispersion of rGO-GP in the solution. Steady-state kinetics studies further showed that the catalytic process conformed to Michaelis-Menten equation and ping-pong mechanism. Benefiting from the excellent peroxidase property of rGO-GP, we have also successfully established a highly sensitive and selective colorimetric detection approach to trace detection of L-cysteine (L-Cys). The limit of detection (LOD) of L-cysteine is 0.1 µM and the linear detection range is 2-30 µM. Furthermore, the nanozyme was successfully applied for detecting L-cysteine in serum. This work therefore demonstrates the advantages of rGO-GP as an effective nanozyme in both its green synthesis and detecting application.

Graphene oxide (GO)-based nanosheets with combined chemo/photothermal/photodynamic therapy to overcome gastric cancer (GC) paclitaxel resistance by reducing mitochondria-derived adenosine-triphosphate (ATP).

BACKGROUND: Paclitaxel (PTX) has been suggested to be a promising front-line drug for gastric cancer (GC), while P-glycoprotein (P-gp) could lead to drug resistance by pumping PTX out of GC cells. Consequently, it might be a hopeful way to combat drug resistance by inhibiting the out-pumping function of P-gp. RESULTS: In this study, we developed a drug delivery system incorporating PTX onto polyethylene glycol (PEG)-modified and oxidized sodium alginate (OSA)-functionalized graphene oxide (GO) nanosheets (NSs), called PTX@GO-PEG-OSA. Owing to pH/thermal-sensitive drug release properties, PTX@GO-PEG-OSA could induced more obvious antitumor effects on GC, compared to free PTX. With near infrared (NIR)-irradiation, PTX@GO-PEG-OSA could generate excessive reactive oxygen species (ROS), attack mitochondrial respiratory chain complex enzyme, reduce adenosine-triphosphate (ATP) supplement for P-gp, and effectively inhibit P-gp's efflux pump function. Since that, PTX@GO-PEG-OSA achieved better therapeutic effect on PTX-resistant GC without evident toxicity. CONCLUSIONS: In conclusion, PTX@GO-PEG-OSA could serve as a desirable strategy to reverse PTX's resistance, combined with chemo/photothermal/photodynamic therapy.

A comparative study of toxicity of graphdiyne and graphene oxide to human umbilical vein endothelial cells.

The success of graphene oxide (GO) has attracted extensive research interests in developing novel 2D nanomaterials (NMs). Graphdiyne (GDY) is a new member of carbon-based 2D NMs possessing sp- and sp2 -hybridized carbon atoms. However, the toxicity of GDY is less investigated as GO. In this study, we compared the toxicity of GDY and GO with human umbilical vein endothelial cells (HUVECs). Exposure to up to 100-µg/ml GDY and GO induced cytotoxicity, but there was no statistically significant difference between GDY and GO. At noncytotoxic concentration, 25-µg/ml GDY or GO led to the internalization of NMs, typically in cytoplasm but not in nuclei. Only GO but not GDY significantly increased THP-1 adhesion onto NM-exposed HUVECs. Meanwhile, compared with GDY, GO more effectively promoted the release of soluble intracellular cell adhesion molecule-1 (sICAM-1), indicating the differential effects of GDY and GO on endothelial activation. Neither GDY nor GO induced intracellular superoxide. However, GO significantly promoted the expression of endoplasmic reticulum (ER) stress genes activating transcription factor 4 (ATF4) and X-box binding protein 1 spliced (XBP-1s), as well pyroptosis genes NLR family pyrin domain containing 3 (NLRP3) and gasdermin D (GSDMD), whereas GDY did not show this effect. The results suggested that GDY and GO could be internalized into HUVECs leading to cytotoxic effects. However, GO was more potent to activate endothelial activation probably due to the activation of ER stress and pyroptosis genes.

Tailoring of bismuth vanadate impregnated on molybdenum/graphene oxide sheets for sensitive detection of environmental pollutants 2, 4, 6 trichlorophenol.

In the present work, we reported a one pot simple colloidal-gel synthesis of molybdenum bismuth vanadate (MoBiVO4). The charge transfer property of MoBiVO4 was improved by developing a composite with graphene oxide (GO) through sonochemical technique. The optical and morphological analysis revealed that successful formation of GO-MoBiVO4 composite without any other filth. As prepared composite was used to modify the superficial surface of glassy carbon electrode (GO-MoBiVO4/GCE) and applied for the selective detection of environmental pollutant 2, 4, 6 trichrlorophenol (TCP). The electron channeling capability of GO with molybdenum bismuth vanadate possessed a superior electrochemical response in cyclic voltammetry (CV), whereas bare GCE and other modified electrodes provided an inferior response with lower current response. The differential pulse voltammetry (DPV) response of TCP at GO-MoBiVO4/GCE outcomes with low level detection of 0.4 nM and higher sensitivity of 2.49 µA µM-1 cm-2 with wider linear response 0.199-17.83 µM. Furthermore, the proposed sensor applied in practicability analysis and the results indicates GO-MoBiVO4/GCE prominent towards electrochemical detection of TCP.

Electrochemiluminescent immunoassay for the determination of CA15-3 and CA72-4 using graphene oxide nanocomposite modified with CdSe quantum dots and Ru(bpy)3 complex.

A novel immunoassay is introduced based on co-reactant enhancing strategy for the electrochemiluminescent (ECL) determination of CA15-3 and CA72-4 tumor markers in real samples. For the preparation of the signaling probe, CA15-3 and CA72-4 antibodies first were labeled using Ru(bpy)32+-N-hydroxysuccinimide ester (Ru(bpy)32+-NHS) and conjugated with L-cysteine capped cadmium selenide (CdSe) quantum dots. Finally, it was cross-linked with chitosan-grafted graphene oxide (GO@CS) nanocomposite. The capture probe was constructed by deposition of multi-walled carbon nanotubes (MWCNT) at the surface of dual-working gold screen-printed electrodes (MWCNT-dwSPE) and covalent attachment of capture CA15-3 and CA72-4 antibodies to MWCNT-dwSPE. ECL signals were recorded by applying cyclic potential ranging from 0.3 to 1.1 V (vs. pseudo-reference Ag/AgCl) at the scan rate of 100 mV.s-1. This immunoassay was used for determination of CA15-3 and CA72-4 in real samples the detection limits of 9.2 µU.ml-1 and 89 µU.ml-1 within linear ranges of 10 µU.ml-1-500 U.ml-1 and 100 µU.ml-1-150 U.ml-1, respectively. This immunoassay also showed acceptable accuracy with recoveries in the range 96.5-108 % and high reproducibility with RSD of 3.1 and 4.9.