Nanocomposite Platform Research Articles

A novel nanocomposite platform of mercaptopropionic acid stabilized CdSe quantum dots-graphene for impedimetric detection of low density lipoprotein

Electrophoretically deposited, 3-mercaptopropionic acid capped CdSe quantum dots (QDs)-grapehene nanpcomposite (rGO-CdSe QDs/ITO) platform have been used for the fabrication of an electrochemical biosensor for detection of low-density lipoprotein (LDL) by immobilizing anti-apolipoprotein B (AAB) via N-ethyl-N’-(3-dimethylaminopropyl carbodiimide N-hydroxysuccinimide) coupling. The modifiedelectrodeswere characterized by various techniques. AAB/rGO-CdSe-QDs/ITO immunoelectrodes studied by EIS revealed detection of LDL in the wide range of 2 mgdL−1–125 mgdL−1.

Treatment of microvascular invasion in hepatocellular carcinoma with drug-loaded nanocomposite platform under synergistic effect of magnetic field/near-infrared light.

Despite progress in clinical treatment, microvascular invasion (MVI) remains a major factor for frequent recurrence and metastasis of hepatocellular carcinoma (HCC) after liver resection and surgery. Thus, this study constructed a target nanoplatform (αCD97-USPIO-Au-DDP) with magnetic field/near-infrared (NIR) light response using ultrasmall superparamagnetic iron oxide-gold nanoporous spheres (USPIO-Au) as multifunctional nanocarrier. Anticancer drug cisplatin (DDP) was loaded, and specifically expressed CD97 protein in MVI was taken as the therapeutic target. The αCD97-USPIO-Au-DDP showed favorable photothermal and stable properties under the NIR light at 808 nm wavelength. As suggested by in vitro and in vivo research, this composite nanopreparation could effectively reduce damage to normal organs and showed good biocompatibility. Excellent magnetic targeting function of nanocarrier and modification of αCD97 strengthened accumulation of composite nanodrug in tumor to inhibit tumor growth. This system may have important ramifications for treatment of MVI in HCC.

Electrophoretically deposited L-cysteine functionalized MoS2@MWCNT nanocomposite platform: a smart approach toward highly sensitive and label-free detection of gentamicin

The exploitation of antibiotics has caused many side effects on the agriculture, environment, and human health. The existing methods have numerous shortcomings in determining gentamicin (GEN), a broad-spectrum antibiotic that causes nephrotoxicity and ototoxicity when found in excess. Here, an immunosensing platform to detect GEN using multiwalled carbon nanotubes (MWCNTs) and molybdenum disulfide (MoS2) nanocomposite, deposited electrophoretically on indium tin oxide (ITO) glass has been developed. A novel 2-D graphene analog MoS2@ MWCNTs nanocomposite was made via a facile and low-cost hydrothermal technique using l-cysteine to achieve remarkable electrochemical properties. Subsequently, a highly sensitive electrochemical immunosensor was fabricated by assembling monoclonal antibodies against gentamicin (anti-GEN) on a MoS2@MWCNTs modified ITO electrode. The hetero-nanostructure formed on the immunosensor surface appeared relatively good conductor for accelerating the electron transfer. GEN was determined on anti-GEN modified electrodes by utilizing the differential pulse voltammetry technique by measuring the difference in current owing to the transfer of electrons directly between the redox species and immunoelectrodes. Under optimal experimental conditions, the fabricated immunosensor had a wide linear detection range of 1 × 10−6–40 μg/mL, a high sensitivity of 13.55 μA (log μg/mL)−1 and a low limit of detection and limit of quantification of 0.039 μg/mL and 0.130 μg/mL, respectively. The developed immunosensor also exhibits high reproducibility, repeatability, and good selectivity against various interferences. This electrochemical immunosensor having MoS2 modified MWCNTs displays the excellent potential for the point-of-care device for GEN testing.

Bimodal Nanocomposite Platform with Antibiofilm and Self-Powering Functionalities for Biomedical Applications.

Advances in microelectronics and nanofabrication have led to the development of various implantable biomaterials. However, biofilm-associated infection on medical devices still remains a major hurdle that substantially undermines the clinical applicability and advancement of biomaterial systems. Given their attractive piezoelectric behavior, barium titanate (BTO)-based materials have also been used in biological applications. Despite its versatility, the feasibility of BTO-embedded biomaterials as anti-infectious implantable medical devices in the human body has not been explored yet. Here, the first demonstration of clinically viable BTO-nanocomposites is presented. It demonstrates potent antibiofilm properties against Streptococcus mutans without bactericidal effect while retaining their piezoelectric and mechanical behaviors. This antiadhesive effect led to ∼10-fold reduction in colony-forming units in vitro. To elucidate the underlying mechanism for this effect, data depicting unfavorable interaction energy profiles between BTO-nanocomposites and S. mutans using the classical and extended Derjaguin, Landau, Verwey, and Overbeek theories is presented. Direct cell-to-surface binding force data using atomic force microscopy also corroborate reduced adhesion between BTO-nanocomposites and S. mutans. Interestingly, the poling process on BTO-nanocomposites resulted in asymmetrical surface charge density on each side, which may help tackle two major issues in prosthetics-bacterial contamination and tissue integration. Finally, BTO-nanocomposites exhibit superior biocompatibility toward human gingival fibroblasts and keratinocytes. Overall, BTO-embedded composites exhibit broad-scale potential to be used in biological settings as energy-harvestable antibiofilm surfaces.

Three dimensional porous Expanded Graphite/Silver Nanoparticles nanocomposite platform as a SERS substrate

Surface enhanced Raman spectroscopy (SERS) is a promising technique for food safety, medical diagnostics and bio-sensing applications, and environmental protection. However, high production costs due to need of sophisticated equipments, relatively poor stability of the present substrates and repeatability problems limit the use of SERS as a routine analysis technique. Hybrid SERS substrates composed of noble metal nanoparticles and graphene-based materials have gained a significant importance since they combine the surface plasmon resonance property of the metal nanoparticles, and the ability of acting as a protective layer for metal nanoparticles against oxidation, SERS enhancement through charge transfer mechanism, flexibility, excellent optical permeability and superior mechanical strength of graphene-based materials. Herein, three dimensional (3D) porous expanded graphite (EG) decorated with silver nanoparticles (AgNPs) was fabricated as a low cost and easy-to-produce SERS platform. 3D and highly porous structure of the EG/AgNPs nanocomposites provided fast penetration of solvent into the substrate, eliminating coffee-ring effect and enabling one to perform fast SERS measurements, as well as allowing to decorate more metal nanoparticles/adsorb more analyte molecules due to high specific surface area. The detection limit of the EG/AgNPs substrates for Rhodamine 6G (R6G) was determined as 10-11 M and the enhancement factor was estimated to be 2.7 × 106. The peaks of 10-11 M R6G was detected even after one month, indicating a high stability and long lifetime of the substrate. This highly stable, sensitive, cost-effective and easy-to-produce EG/AgNPs nanocomposite substrate exhibit a great potential to promote application of SERS for routine analyses.

An Electrochemical Aptamer Biosensor for Bisphenol A on a Carbon Nanofibre‐silver Nanoparticle Immobilisation Platform

AbstractA nanocomposite platform of silver nanoparticles and carbon nanofibres (AgCNFs) was used to immobilise a bisphenol A specific 63‐mer ssDNA aptamer to form a biosensor. The fabrication process of the biosensor was studied with electrochemical impedance spectroscopy and cyclic voltammetry in the presence of [Fe(CN)6]3−/4− as redox probe. The biosensor detected bisphenol A in a linear range of 0.1–10 nM, with a limit of detection of 0.39 nM using square wave voltammetry (SWV). The biosensor exhibited good selectivity in the presence of interfering species at 100‐fold concentrations and was used to detect BPA in real water sample.

Prolonged proliferation and delayed senescence of the adipose-derived stem cells grown on the electrospun composite nanofiber co-encapsulated with TiO2 nanoparticles and metformin-loaded mesoporous silica nanoparticles

This study was aimed to investigate the effects of the Poly-ε-Caprolactone/Gelatin nanofibers (PCL/GEL NFs) co-encapsulated with TiO2 nanoparticles (nTiO2) and metformin-loaded mesoporous silica nanoparticles (MET@MSNs) on prolonging the in vitro expansion of human adipose-derived stem cells (hADSCs) without inducing cellular senescence and aging. FTIR, BET, FE-SEM, and TEM were applied to characterize the fabricated MET@MSNs and electrospun composite NFs. The presence of inorganic particles, nTiO2 and MSNs, in the scaffolds improved their mechanical properties and led to a more sustained release of MET with almost the lack of the initial burst release from nTiO2/MET@MSNs-loaded NFs. The enhanced adhesion, metabolic activity, and proliferation rate of the hADSCs grown on nTiO2/MET@MSNs-loaded NFs were demonstrated via FE-SEM images, MTT test and PicoGreen assay, respectively, over 28 days of culture. Furthermore, the irregular nanofibrillar structures and the impact of sustained release of MET led to a significant upregulation in the mRNA levels of autophagy (Atg-5, Atg-7, Atg-12, and Beclin-1) and stemness (Nanog3, Sox-2, and Oct-4) markers as well as a considerable down-regulation of p16INK4A senescence marker. Further, the upregulation of hTERT, enhanced activity of telomerase, and increased telomere length were more pronounced in the hADSCs cultured on nTiO2/MET@MSNs-loaded NFs as compared to other types of NFs. Overall, our findings demonstrated the potential of the fabricated nanocomposite platform for counteracting cellular senescence and achieving sufficient quantities of fresh hADSCs with preserved stemness for various stem cell-based regenerative medicine purposes.

Hydrothermally synthesized mesoporous CS-g-PA@TSM functional nanocomposite for efficient photocatalytic degradation of Ciprofloxacin and treatment of metal ions

Tin-based ternary inorganic semiconductors enable new opportunities for the development of functional hydrogel nanocomposites to cope with environmental pollution. In this regard, we have synthesized highly functionalize CS-g-PA@TSM nanocomposites by the impregnation of Tin- Si/Mo (TSM) semiconductor in the matrix of chitosan/polyacrylamide (CS-g-PA) using the hydrothermal route. Multifunction platform showed ammonia vapor sensing, fluorescent detection as well as removal and exchange recovery of lead ions from wastewater and its photocatalytic behavior towards antibiotic degradation. The CS-g-PA@TSM nanocomposite achieved almost 96% photodegradation towards Ciprofloxacin (CIP) after 130 min of irradiation which was further monitored and confirmed by 3-D excitation-emission matrix fluorescence and GC–MS techniques, respectively. The photocatalytic mechanism of the CS-g-PA@TSM under visible light irradiation was clarified, which established the generation of O2− / OH species in the form of dominant radicals. The experimental results indicated that the improved photocatalytic performance of CS-g-PA@TSM could be attributed to enhance the optical absorption and efficient separation along with the migration of photoinduced charge carriers. The nanomaterial also exhibits significant Pb2+ recovery (95.6%) from wastewater with a limit of detection (LOD) and limit of quantification (LOQ) as 3.38 μg L−1 and 9.34 μg L−1, respectively. The CS-g-PA@TSM nanocomposite was successfully employed up to five regeneration cycles with 98% regeneration capacity. Thus, the finding of the present study establishes that the multifunctional CS-g-PA@TSM nanocomposite platform could be used for the treatment of antibiotics (CIP), ammonia, and Pb2+ from wastewater.

Hybrid Nanocomposite Platform, Based on Carbon Nanotubes and Poly(Methylene Blue) Redox Polymer Synthesized in Ethaline Deep Eutectic Solvent for Electrochemical Determination of 5-Aminosalicylic Acid.

A novel hybrid composite of conductive poly(methylene blue) (PMB) and carbon nanotubes (CNT) was prepared for the detection of 5-aminosalicylic acid (5-ASA). Electrosynthesis of PMB with glassy carbon electrode (GCE) or with carbon nanotube modified GCE was done in ethaline deep eutectic solvent of choline chloride mixed with ethylene glycol and a 10% v/v aqueous solution. Different sensor architectures were evaluated in a broad range of pH values in a Britton-Robinson (BR) buffer using electrochemical techniques, chronoamperometry (CA), and differential pulse voltammetry (DPV), to determine the optimum sensor configuration for 5-ASA sensing. Under optimal conditions, the best analytical performance was obtained with CNT/PMBDES/GCE in 0.04 M BR buffer pH 7.0 in the range 5–100 µM 5-ASA using the DPV method, with an excellent sensitivity of 9.84 μA cm−2 μM−1 (4.9 % RSD, n = 5) and a detection limit (LOD) (3σ/slope) of 7.7 nM, outclassing most similar sensors found in the literature. The sensitivity of the same sensor obtained in CA (1.33 μA cm−2 μM−1) under optimal conditions (pH 7.0, Eapp = +0.40 V) was lower than that obtained by DPV. Simultaneous detection of 5-ASA and its analogue, acetaminophen (APAP), was successfully realized, showing a catalytic effect towards the electro-oxidation of both analytes, lowering their oxidation overpotential, and enhancing the oxidation peak currents and peak-to-peak separation as compared with the unmodified electrode. The proposed method is simple, sensitive, easy to apply, and economical for routine analysis.

Electro-Stimulated Release of Poorly Water-Soluble Drug from Poly(Lactic Acid)/Carboxymethyl Cellulose/ZnO Nanocomposite Film.

Among various types of external stimuli-responsive DDS, electric-responsive DDS are more promising carriers as they exploit less complex, easily miniaturized electric signal generators and the possibility of fine-tuning the electric signals. This study investigates the use of intrinsically biocompatible biopolymers in electro-simulative drug delivery to enhance the release of poorly-soluble/non-ionic drug. CMC/PLA/ZnO/CUR nanocomposite films were prepared by the dispersion of CMC and ZnO NPs in solubilized PLA/curcumin medium, followed by solvent casting step. Curcumin is poorly water-soluble and used as the model drug in this study. The films with different contents of CMC, PLA and ZnO NPs were characterized using FTIR, impedance spectroscopy, tensile testing and FESEM imaging. The in vitro drug release of the films was carried out in deionized water under DC electric field of 4.5V. The ionic conductivity of the films increased with increasing the CMC concentration of the film. The addition of a small amount of ZnO NPs (2%) successfully restored the tensile properties of the film. In response to the application of the electric field, the composite films released drug with a near-linear profile. There was no noticeable amount of passive diffusion of the drug from the film with the absence of the electric field. The outcome of this study enabled the design of an electric-responsive nanocomposite platform for the delivery of poorly water-soluble/non-ionic drugs. Graphical abstract.

Fabrication of poly(3,4-ethylenedioxythiophene)-iridium oxide nanocomposite based Tyrosinase biosensor for the dual detection of catechol and azinphos methyl

A novel, sensitive and simple amperometric biosensor for the determination of catechol and azinphos methyl based on Tyrosinase enzyme inhibition has been developed. The biosensor was prepared from iridium (IV) oxide, Poly (3,4 ethylenedioxythiophene) nanocomposite, and Tyrosinase immobilized by crosslinking with glutaraldehyde in this nanocomposite platform. Biosensor was successfully used for the dual determination of catechol and azinphos methyl using fixed potential amperometry. Biosensor performance was optimized in terms of iridium (IV) oxide, Poly (3,4 ethylenedioxythiophene) and Tyrosinase. The surface morphology of the enzyme electrode was characterized by scanning electrochemical microscopy, atomic force microscopy, cyclic voltammetry and electrochemical impedance. Under optimized conditions, linear relationships were achieved in the range 0.05−10.65 μM for catechol and 10−200 μM for azinphos methyl. Limit of detection was found as 0.017 μM for catechol and 2.964 μM for azinphos methyl with acceptable repeatability and reproducibility. Finally, developed biosensor was successfully applied to the detection of azinphos methyl tap water, waste water, well water, human urine, serum and saliva.

Micropatterned Biphasic Nanocomposite Platform for Maintaining Chondrocyte Morphology.

One major limitation hindering the translation of in vitro osteoarthritis research into clinical disease-modifying therapies is that chondrocytes rapidly spread and dedifferentiate under standard monolayer conditions. Current strategies to maintain rounded morphologies of chondrocytes in culture either unnaturally restrict adhesion and place chondrocytes in an excessively stiff mechanical environment or are impractical for use in many applications. To address the limitations of current techniques, we have developed a unique composite thin-film cell culture platform, the CellWell, to model articular cartilage that utilizes micropatterned hemispheroidal wells, precisely sized to fit individual cells (12-18 μm diameters), to promote physiologically spheroidal chondrocyte morphologies while maintaining compatibility with standard cell culture and analytical techniques. CellWells were constructed of 15-μm-thick 5% agarose films embedded with electrospun poly(vinyl alcohol) (PVA) nanofibers. Transmission electron microscope (TEM) images of PVA nanofibers revealed a mean diameter of 60.9 ± 24 nm, closely matching the observed 53.8 ± 29 nm mean diameter of human ankle collagen II fibers. Using AFM nanoindentation, CellWells were found to have compressive moduli of 158 ± 0.60 kPa at 15 μm/s indentation, closely matching published stiffness values of the native pericellular matrix. Primary human articular chondrocytes taken from ankle cartilage were seeded in CellWells and assessed at 24 h. Chondrocytes maintained their rounded morphology in CellWells (mean aspect ratio of 0.87 ± 0.1 vs three-dimensional (3D) control [0.86 ± 0.1]) more effectively than those seeded under standard conditions (0.65 ± 0.3), with average viability of >85%. The CellWell's design, with open, hemispheroidal wells in a thin film substrate of physiological stiffness, combines the practical advantages of two-dimensional (2D) culture systems with the physiological advantages of 3D systems. Through its ease of use and ability to maintain the physiological morphology of chondrocytes, we expect that the CellWell will enhance the clinical translatability of future studies conducted using this culture platform.

Direct Cytosolic Delivery of Proteins through Coengineering of Proteins and Polymeric Delivery Vehicles.

Nanocarrier-mediated protein delivery is a promising strategy for fundamental research and therapeutic applications. However, the efficacy of the current platforms for delivery into cells is limited by endosomal entrapment of delivered protein cargo with concomitantly inefficient access to the cytosol and other organelles, including the nucleus. We report here a robust, versatile polymeric-protein nanocomposite (PPNC) platform capable of efficient (≥90%) delivery of proteins to the cytosol. We synthesized a library of guanidinium-functionalized poly(oxanorborneneimide) (PONI) homopolymers with varying molecular weights to stabilize and deliver engineered proteins featuring terminal oligoglutamate "E-tags". The polymers were screened for cytosolic delivery efficiency using imaging flow cytometry with cytosolic delivery validated using confocal microscopy and activity of the delivered proteins demonstrated through functional assays. These studies indicate that the PPNC platform provides highly effective and tunable cytosolic delivery over a wide range of formulations, making them robust agents for therapeutic protein delivery.

CuS@PDA-FA nanocomposites: a dual stimuli-responsive DOX delivery vehicle with ultrahigh loading level for synergistic photothermal-chemotherapies on breast cancer.

In this study, CuS@PDA nanoparticles were synthesized and used to create a novel tumor-targeting nanocomposite platform composed of copper sulfide@polydopamine-folic acid/doxorubicin (CuS@PDA-FA/DOX) for performing both photothermal and chemotherapeutic cancer treatment. The nanocomposite platform has ultrahigh loading levels (4.2 ± 0.2 mg mg-1) and a greater photothermal conversion efficiency (η = 42.7%) than CuS/PDA alone. The uptake of CuS@PDA-FA/DOX nanocomposites is much higher in MCF-7 cells than in A549 cells because MCF-7 cells have much higher folic acid receptors than A549. Under near infrared (NIR) irradiation, the CuS@PDA-FA/DOX system using a synergistic combination of photothermal therapy and chemotherapy yields a better therapeutic effect than either photothermal therapy or chemotherapy alone. The treatment is very effective with the cell viability is only 5.6 ± 1.4%.

Low-potential immunosensor-based detection of the vascular growth factor 165 (VEGF165) using the nanocomposite platform of cobalt metal-organic framework.

The vascular endothelial growth factor 165 (VEGF165) is a quintessential biomarker in cancers. An easy and precise tool for the early detection of malignancies is required for rapid care and metastasis prevention. Cobalt-based metal–organic framework (Co-BTC-GO-MOF) nanoparticles have been used as a signal carrier for the anti-VEGF165 signaling antibody. Cobalt-based MOF was synthesized using cobalt (Co), benzene-1,3,5-tricarboxylate (BTC), and graphene oxide (GO) applying a hydrothermal method. Structure, compositions, size and morphology of the qualified sensor are determined by using distinctive analytical techniques. The Co-MOF nanoparticles are found to be thermostable, as revealed by thermal stability assay. The strategy utilises an impedimetric and differential pulse voltammetry (DPV) techniques in the presence of the [Fe(CN)6]3−/4− redox system. Compared to earlier results, this assay resulted in higher sensitivity with the limit of detection (LOD) found to be 5.23 pM in a 0.01 M buffer solution of pH 7.4 using linear scale voltammetry at room temperature. The resulting Co-BTC-GO-MOF immunosensor shows high responsiveness and selectivity in detecting VEGF165 in real-time serum samples of cancer patients. The electrochemical performance studies confirm that the intended proposed immunosensor could pave the way for the future advancement of high-performance, sensitive, reproducible and robust immunosensors for the cost-effective and initial phase detection of cancer in the future.

Micelle-nanogel platform for ferulic acid ocular delivery.

Corneal wound healing after a trauma or a chemical injury has been shown to correlate with antioxidant levels at the ocular surface. However, ocular bioavailability of efficient antioxidants (e.g. ferulic acid) after topical administration is limited by their poor solubility, low stability and short residence time. The aim of this work was to formulate ferulic acid in a nanocomposite platform composed of nanogels and micelles for efficient delivery to cornea. Solubility enhancement factor of ferulic acid was found to be equal to 1.9±0.3 and 3.4±0.3 for 50 and 100mg/ml Pluronic® F68 micellar solutions. Hyaluronan was added to blank and ferulic acid loaded micelles, and then cross-linked with ε-polylysine. Hyaluronan nanogels showed dimensions of ~300nm with positive zeta potential values. The formulations were characterized in terms of rheological behavior, biocompatibility, wound healing properties, ferulic acid release pattern and penetration into excised bovine corneas. In comparison to Pluronic® micelles that released ferulic acid rapidly, micelle-nanogel composites sustained the release up to 2days. Furthermore, the micelle-nanogel formulation favored in vitro wound closure promoting fibroblasts growth and ex vivo accumulation of ferulic acid into both healthy and damaged corneas (>100µg/cm2).

Sub-micron calcium carbonate as a template for the preparation of dendrite-like PANI/CNT nanocomposites and its corrosion protection properties

The dendrite-like polyaniline/carbon nanotube (PANI/CNT) nanocomposites have been successfully prepared through the oxidative polymerization of aniline on the surface of nanocomposites of sub-micron calcium carbonate composites and CNT, in acid aqueous solution. With calcium carbonated composing, the adherent dendrite-like PANI forms on the CNT surface. The possible mechanism is the turbulence around CNT due to the gas carbon dioxide formed by decomposition of calcium carbonate template, that leads to forming this unique composite morphology. The obtained PANI/CNT nanocomposites exhibit excellent redox capability not only in acidic but also in neutral medium due to the interfacial π-π interactions between CNT and PANI. The PANI/CNT nanocomposites are found to be easily dispersed into the aqueous waterborne acrylate-amino (AA) resin. The AA coating filled with PANI/CNT has 76 days resistance against 3.5 wt% NaCl solution at 65 °C, which is higher than 29 days for the AA coating contained PANI and much higher than 60 h for the unfilled AA coating. The superior corrosion protection mechanisms are revealed to be the “labyrinth effect” of nanocomposites and “anodic protection” of passivation film. Therefore, this strategy and nanocomposite platform may have high potential in corrosion protection area.

In-situ generated Mn3O4-reduced graphene oxide nanocomposite for oxygen reduction reaction and isolated reduced graphene oxide for supercapacitor applications

We have generated in situ nanocomposite of Mn3O4 and reduced graphene oxide (rGO) upon employing wet-chemical reduction of graphene oxide (GO) by Mn(II) salt as mild-reducing agent for the first time and examined the oxygen reduction reaction (ORR) activity in 0.1 M KOH electrolyte. The half-wave potential (E1/2) of the nanocomposite catalyst (20% Mn3O4-rGO/C) was found to be around −0.153 V which is only ∼87 mV negative from the commercially available catalyst (20% Pt/C). Remarkably, after 5000 linear sweep voltammetry cycles the E1/2 shifted marginally by 20 mV; and the number of electrons transferred during ORR was estimated to be close to 4. Such an efficient electrocatalytic performance of the nanocomposite was primarily attributed to the synergistic interaction between Mn3O4 and rGO. The fabricated all-solid-state supercapacitor of rGO (extracted from the nanocomposite) in aqueous polyvinyl alcohol-sulfuric acid (PVA-H2SO4) gel polymer electrolyte (GPE) showed CS value of ∼310 F/g at a current density of 1 A/g along with long durability (10,000 charge-discharge cycles). All-solid-state flexible rGO supercapacitor exhibited high-flexibility and excellent durability (30,000 cycles with 100% retention of CS). Our results provide an enormous opportunity in designing transition metal oxides decorated semiconducting reduced graphene oxide nanocomposite platforms for various electrochemical applications.

Graphene- and Graphene Oxide-Based Nanocomposite Platforms for Electrochemical Biosensing Applications.

Graphene and its derivatives such as graphene oxide (GO) and reduced GO (rGO) offer excellent electrical, mechanical and electrochemical properties. Further, due to the presence of high surface area, and a rich oxygen and defect framework, they are able to form nanocomposites with metal/semiconductor nanoparticles, metal oxides, quantum dots and polymers. Such nanocomposites are becoming increasingly useful as electrochemical biosensing platforms. In this review, we present a brief introduction on the aforementioned graphene derivatives, and discuss their synthetic strategies and structure–property relationships important for biosensing. We then highlight different nanocomposite platforms that have been developed for electrochemical biosensing, introducing enzymatic biosensors, followed by non-enzymatic biosensors and immunosensors. Additionally, we briefly discuss their role in the emerging field of biomedical cell capture. Finally, a brief outlook on these topics is presented.

(Invited) Nano Composite Platforms: Synthesis and Biological Applications Including Cancer Diagnosis

Nanometal-polymer composite films are hybrid materials with inorganic nanoparticles immobilized and uniformly dispersed into a polymer matrix. Nanoparticles such as gold and silver, used to enhance the optical properties of the polymers, are called `optically effective additives` as they lead to new functionalities of the polymer based materials. Au (Ag)-polymer and copolymer composite films are suitable for applications such as waveguides, color filters, thermo-chromic materials etc. The strong plasmon band of Au and Ag nanoparticles (Localized Surface Plasmon Resonance) in the visible spectrum, that originates from the excitation of plasmons by the incident light, makes noble metal-polymer nanocomposites particularly adequate for sensing and biosensing applications. Furthermore, association of Au and Ag nanoparticles of various shapes with poly(dimethylsiloxane) (PDMS), allows the use of nanocomposite materials for microfluidic biosensing as well. In this presentation, we will talk about the in-situ synthesis of Au-PDMS and Ag-PDMS nanocomposites both at the macroscale and inside the channel of a microfluidic chip. The in-situ synthesis of nanoparticles involves the reduction of gold ions in a gold precursor solution by the curing agent of the polymer. The kinetics of the reaction has been investigated and the effect of annealing temperature on the morphology of nanoparticles has been studied by using imaging and spectroscopic methods. The nanocomposite has been successfully used for sensing of antibody-antigen interactions, allowing the detection of various important proteins. Nanocomposies of metals integrated into other polymers such as PMMA, PVA, and PS have been synthesized as well by using UV, microwave and thermal reduction methods. The effect of the particle`s shape on the properties of nanocomposites and their sensing abilities has also been studied by synthesizing nanostar particles and integrating them into microchannels. Because of the biocompatibility and non-toxicity of gold and silver nanoparticles, their nanocomposites can be used for plasmonic detection of biological entities in cancer research.