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Quantitative detection of cancer biomarkers with higher accuracy and sensitivity provides an effective platform for screening, monitoring, early diagnosis, and disease surveillance. The present work demonstrates the fabrication and application of fluorescent turn-on biosensor for ultrasensitive detection of small cell lung cancer biomarker utilizing biofunctionalized graphene quantum dots as the energy donor and gold nanoparticles (AuNPs) as the energy acceptor. One-pot and the bottom-up hydrothermal route have been employed for the synthesis of in situ amine-functionalized and nitrogen-doped graphene quantum dots (amine-N-GQDs) and further characterized experimentally by different analytical techniques. The molecular simulation studies were performed using the Material Studio software for optimizing the possible chemical structure of synthesized amine-N-GQDs, a comprehensive analysis of experimental results to validate the presence of potential N-doping and amine functionalization sites. Then monoclonal neuron-specific enolase antibodies (anti-NSE) were covalently immobilized to amine-N-GQDs to provide the biofunctionalized GQDs (anti-NSE/amine-N-GQDs). A label-free and efficient fluorescent biosensor based on nanosurface energy transfer (NSET) between anti-NSE/amine-N-GQDs and AuNPs has been developed for neuron-specific enolase (NSE) detection. The fluorescence response studies of anti-NSE/amine-N-GQDs@AuNPs nanoprobe conducted as a function of NSE antigen exhibited fast response time (16 min), broader linear detection range (0.1 pg mL −1 to 1000 ng mL −1 ), and remarkably low detection limit (0.09 pg mL −1 ). Additionally, the fluorescent biosensor exhibited excellent performance in real samples, with an average recovery value of 94.69%.

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Graphene quantum dots (GQDs) are one of the most promising luminescent carbon derived nanomaterials decorated with multiple useful functional groups and remarkable optoelectronic properties. Heteroatom doping of hexagonal carbon sheet of GQDs is an effective strategy to tailor their properties to meet desired application. In this work, sulfur doped GQDs (S-GQDs) were synthesized by simply pyrolyzing citric acid (CA) as a source of carbon and 3-Mercaptopropionic acid as a source of sulfur dopant. The optimal reaction conditions (ratio of the carbon to dopant source, temperature and time of reaction) were obtained while investigating their effect on the quantum yield and fluorescence properties of GQDs and, are hereby, reported for the first time. The as-synthesized S-GQDs were extensively characterized by different analytical techniques such as transmission electron microscopy (TEM), UV-vis Spectroscopy (UV), Fourier transform infrared spectroscopy, photoluminescence (PL) and x-ray Photoelectron Spectroscopy. S-GQDs were found uniform in size (∼4 nm) and spherical in shape with strong blue fluorescence. Further, for in-depth analysis of experimental results and underlying phenomena, theoretical studies based on density functional theory were performed for chemical structure optimization, possible sites of doping and density of states calculation. The synthesized S-GQDs exhibited excellent solubility in water, a stronger fluorescence and desirably higher quantum yield (57.44%) as compared to that of previously reported undoped GQDs. These successfully demonstrated unique and improved properties of S-GQDs present them as a potential candidate for biomedical, optical, electrical and chemical applications.

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Being a novel and interesting zero-dimensional material of carbon family, graphene quantum dots (GQDs), have been studied extensively in the last few years due to their exceptional and desirable optical,...

In the current work, renewable resourced toughened epoxy blend has been developed using epoxidized linseed oil (ELO) and bio-based crosslinker. Epoxidation of linseed oil was confirmed through FTIR and 1 H NMR spectra. The ELO bio-resin was blended at different compositions (10, 20, and 30 phr) with a petroleum-based epoxy (DGEBA) as reactive diluent to reduce the viscosity for better processibility and cured with cardanol-derived phenalkamine to overcome the brittleness. The flow behavior of the neat epoxy and modified bio-epoxy resin blend systems was analyzed by Cross model at low and high shear rates. The tensile and impact behavior studies revealed that the toughened bio-epoxy blend with 20 to 30 phr of ELO showed moderate stiffness with much higher elongation at break 7% to 13%. Incorporation of higher amount of ELO (20 to 30 phr) increases enthalpy of curing without affecting peak temperature of curing. The thermal degradation behavior of the ELO based blends exhibits similar trend as neat epoxy.The higher intensity or broadened loss tangent curve of bio-epoxy blends revealed higher damping ability. FE-SEM analysis showed a rough and rippled surface of bio-based epoxy blends ensuring effective toughening. Reduced viscosity of resin due to maximum possible incorporation of bio-resin and use of phenalkamine as curing agent leads to an eco-friendly toughened epoxy and can be useful for specific coating and structural application. KEYWORDSbio-based epoxy, epoxidized oil, phenalkamine, thermomechanical properties, toughening Functionalized vegetable oils have been reported as renewable resourced toughening diluents for epoxy to overcome its inherent brittleness. [5][6][7][8][9][10][11][12][13][14][15][16] Particularly, epoxidized oils having multiple epoxy groups are more preferable to be used as reactive diluents being eco-friendly and ease synthesis process. Soybean oil due to ease of availability, higher number of reacting sites (4.6 double bonds per triglyceride chain), and low cost has attracted attention of researchers in employing it to enhance toughness of petro-based epoxies in the last decade. However, the tensile and thermal properties of epoxy drastically reduce with increase in ESO content because of its lower reactivity, low oxirane content, and inferior crosslink density. 5-10Further, the wide use of soybean oil in thermoset and thermoplastic has been reported on ELO-based bio-epoxy blends using bio-renewable PKA as curing agent.In the current work, ELO was synthesized through in-situ method, and bio-epoxy blends were prepared with varying ELO content as reactive diluent. The diluent content can be optimized based on rheological, mechanical, and thermo-mechanical specification needed for specific structural application. | Synthesis of epoxidized linseed oilLinseed was epoxidized through in-situ method in the presence of glacial acetic acid and hydrogen peroxide as reported earlier by Kim et al 6 and Sahoo et al. 13 Epoxidation of oil was performed in a 3-necked flask equipped with a magnetic st...

This study explores the hybridizing effect of mechano-chemical activated y-ash (FA) in sisal ber reinforced polymer composites. Activation and resistance against agglomeration of FA has been achieved by modifying it with 2, 4, and 6 wt.% of the cetyltrimethylammonium bromide (C-tab). FA activation with C-tab and particle size reduction to nano-level (<1µm) have been appropriately achieved with a planetary ball milling and the same has been con rmed from the dynamic light scattering technique. The hybrid composite containing 25 wt.% of sisal ber and 5 wt.% of (6 wt.% C-tab) treated FA shows much improved tensile (40.12 MPa), exural (53.27 MPa), and impact strengths (0.75 kJ/m 2 ) than that of neat PP and composite reinforced with only 30 wt.% of sisal ber. This increase in tensile and exural strength was 30.54% and 48% higher than neat PP. Maximum notched impact strength of 0.80 kJ/m 2 have been reported by hybrid composite containing FA treated with 2 wt.% of the C-tab.Micromechanical modelling using a combination of rule of mixture and inverse rule of mixture separately with Halpin-Tsai predicted a value close to the experimental Young's modulus. DSC studies showed an increment in the composite's crystallinity upon ber addition. Morphological analysis of the hybrid composite revealed good wettability of reinforcing ber and FA within the matrix, whereas TGA showed an improved thermal stability of the composites.