Label-free and sensitive detection of PSA (Prostate Specific Antigen) is still a big challenge in the arena of prostate cancer diagnosis in males. We present a comparative study for label-free PSA ...aptasensor and PSA immunosensor for the PSA-specific monoclonal antibody, based on graphene quantum dots-gold nanorods (GQDs-AuNRs) modified screen-printed electrodes. GQDs-AuNRs composite has been synthesized and used as an electro-active material, which shows fast electron transfer and catalytic property. Aptamer or anti-PSA has immobilized onto the surface of modified screen printed electrodes. Three techniques are used simultaneously, viz. cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedence spectroscopy (EIS) to investigate the analytical performance of both PSA aptasensor and PSA immunosensor with its corresponding PSA antigen. Under optimum conditions, both sensors show comparable results with an almost same limit of detection (LOD) of 0.14 ng mL
. The results developed with aptasensor and anti-PSA is also checked through the detection of PSA in real samples with acceptable results. Our study suggests some advantages of aptasensor in terms of better stability, simplicity and cost effectiveness. Further our present work shows enormous potential of our developed sensors for real application using voltammetric and EIS techniques simultaneous to get reliable detection of the disease.
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•An extremely simple and effective strategy for directional growth of poly (3-hexylthiophene) nanowires.•Macroscopic alignment of P3HT nanowires was obtained using off – center spin ...coating.•GIXD and HR-TEM demonstrated highly crystalline π–π stacked lamellar structure.•H – like aggregation of polymer chains with extended conjugation length in P3HT-DCM.•Highly oriented and crystalline P3HT nanowires film exhibited average mobility of 0.053 cm2V−1s−1.
Controlling the morphology, molecular packing and alignment of conjugated polymer remain a primary challenge that hinders their widespread applications in electronic and optoelectronic devices. Here, we have demonstrated an extremely simple and effective strategy for nucleation and growth of highly crystalline and aligned nanowires of regioregular poly (3-hexylthiophene) (P3HT) in the solvent that exhibits a remarkable enhancement in charge transport properties. We have used the combination of marginal solvent (dichloromethane) and ultrasonication to obtain highly crystalline, aligned and ordered nanowires of P3HT by means of off-center spin coating and compared with their on-center counterparts also. Macroscopically ordered and aligned nanowires of P3HT are confirmed by atomic force microscopy (AFM) and polarized optical microscopy (POM). Grazing incidence X-ray diffraction (GIXD) and high-resolution transmission electron microscopy (HR-TEM) demonstrated highly crystalline π–π stacked lamellar structure. The organic field-effect transistors (OFETs) based on highly oriented and crystalline P3HT nanowires exhibited a 50-fold enhancement in charge carrier mobility (average mobility 0.053 cm2V−1s−1) compared to OFETs based on P3HT film prepared in a good solvent (chloroform), measured under the ambient condition. The results are further supported by UV–vis spectroscopy, cyclic voltammetry, and theoretical calculation. Our study is a promising strategy for achieving large-scale aligned nanostructures of solution processable conjugated polymer film to enable high-performance organic electronic devices.
Layered double hydroxides (LDHs) hinder corrosive elements by forming a double layer and locking them between its layers. Hence, LDHs are interesting materials in corrosion inhibition. In this work, ...Zn-Mg-based LDHs are grown over a copper substrate by using a hydrothermal method. Two types of Zn-Mg-based LDH coating are prepared based on hydrothermal reaction time. Both types are characterized through Fourier transform infrared spectroscopy, Raman spectroscopy, high-resolution scanning electron microscopy, energy dispersive X-ray analysis, atomic force microscopy, and X-ray diffraction. Results show that the two types of LDH coating are successfully grown on copper; however, they differ in thickness and structural configuration. Corrosion testing of the LDH coatings is executed in 0.1 M NaCl and 0.1 M NaOH through alternating current impedance measurements and Tafel polarization curves. Results show that L48 gives more than 90% protection to copper, which is higher than the protection provided by L24. However, both LDH coatings (L24 and L48) are more effective corrosion inhibitors in NaCl than in NaOH, suggesting that the LDH coatings can more efficiently exchange Cl ions than OH ions.
The electrical and ammonia gas sensing properties of poly (3, 3"'-dialkylquaterthiophene) (i.e., PQT-12) and CdSe quantum dots (QDs) composite-based back-gated organic thin film transistors (OTFTs) ...fabricated on SiO 2 coated heavily doped p-Si substrates by solution method have been investigated in this paper. The properties of pristine PQT-12 and PQT-12/CdSe QDs composite films have been investigated by transmission electron microscopy and atomic force microscopy. To investigate the effect of colloidal CdSe QDs on the characteristics of PQT-12-based OTFTs, the performance of pristine PQT-12-based OTFT has been compared with that of the PQT-12/CdSe QDs composite-based OTFT. The field effect mobility, threshold voltage, on/off current ratio, and subthreshold swing of the PQT-12/CdSe QDs composite-based OTFT are 4.2×10 -3 cm 2 /Vs, -14.4 V, 1.9×10 3 , and 5.2 V/dec while the corresponding values for pristine PQT-12-based OTFT are 1.4× 10 -3 cm 2 /Vs, -22.1 V, 3.6× 10 2 , and 7.9 V/dec, respectively. When the devices are exposed to ammonia gas, an estimated gas response of ~51% is obtained for PQT-12/CdSe QDs composite-based OTFT whereas the gas response of ~41% is achieved for the pristine PQT-12 OTFT sensor. The improved gas response in the PQT-12/CdSe QDs composite-based OTFT is attributed to enhanced charge transfer due to the CdSe QDs as compared with the pristine PQT-12-based OTFT.
Fatty acid molecules 9,12,15-octadecatrienoic acid (C18:3), 9,12-octadecadienoic acid (C18:2), and hexadecanoic acid (C16:0) possessing active functional groups with the capability of fast electron ...transfer have been established for effective corrosion inhibition of mild steel. In this regard, a microalga Scenedesmus sp. is isolated and its fatty acids have been studied to corroborate the adsorption behavior, attributing the anticorrosion efficacy on mild steel in 1 M HCl solution by forming metal–inhibitor framework. Electrochemical analysis has been used to ascertain the surpassing corrosion inhibition efficiency at an optimal concentration of 36 ppm with maximum 95.1% inhibitive performance. The results of metallography with or without the inhibitor molecules have indicated significant changes in surface morphology of mild steel specimen for gradual enhancement in immersion time (72 h). Hydrogen evolution reaction has been emphasized to observe the tendency of significant decrease in the bubble formation in the presence of inhibitor compared to 1 M HCl solution only. Surface morphometric studies (scanning electron microscopy and atomic force microscopy) have also revealed the excellent adsorption capacity of Scenedesmus fatty acids on metal surface. Quantum chemical calculations, performed by density functional theory, determined significant adsorption effectiveness, based on the donor–acceptor capability between metallic surface and inhibitor molecules.
The inhibition effect of aqueous
Argemone mexicana
root extract (AMRE) on mild steel corrosion in 1 M HCl has been studied by weight loss, Tafel polarization curves, electrochemical impedance ...spectroscopy, scanning electron microscopy (SEM), and atomic force microscopy techniques. Results indicate that inhibition ability of AMRE increases with the increasing amount of the extract. A maximum corrosion inhibition of 94 % is acknowledged at the extract concentration of 400 mg L
−1
. Polarization curves and impedance spectra reveal that both cathodic and anodic reactions are suppressed due to passive layer formation at the metal–acid interface. It is also confirmed by SEM micrographs and FTIR studies. Furthermore, the effects of acid concentration (1–5 M), immersion time (120 h) and temperature (30–60 °C) on inhibition potential of AMRE have been investigated by the weight loss method and electrochemical techniques. An adsorption mechanism is also proposed on the basis of weight loss results, which shows good agreement with the Langmuir isotherm.
The soluble poly-3-hexylthiophene (P3HT) based organic field effect transistors (OFETs) are fabricated and sensitivity of the device to ammonia vapour at room temperature is subsequently tested. The ...performance parameters of the OFET in air, water vapour and ammonia have been studied in order to explore the potential of this device as an ammonia sensor. The device parameters like drain–source current, mobility and threshold voltage are found to change significantly when the device is exposed to various concentrations of ammonia. The P3HT based OFET shows excellent response to ammonia in the range of 0.1–25ppm at room temperature.
We describe ninety second electrosynthesis of uniform palladium nanocubes on ITO without any surfactants, templates or premodifications of ITO surfaces. The electrodeposition potential and ...concentration of palladium precursor are varied for the formation of Pd nanocubes. Electrosynthesized palladium nanocubes have been characterized by various techniques. Further electrosynthesized palladium nanocubes are employed in electrosensing of cefotaxime drug without using any redox mediator or enzyme. The developed amperometric electrochemical sensor under the optimum conditions is convenient and applicable for the determination of cefotaxime drug with a sensitivity of 2.724 µA/µM and 0.062 µM limit of detection at S/N (signal‐to‐noise ratio):3.
A novel methanol derived graphene (MDG) and gentamicin sulfate nanohybrid was prepared, and the loading and release behaviour of gentamicin on MDG is investigated. An efficient drug loading of 2.57 ...mg mg(-1) was obtained at pH 7. By applying release kinetic models, the mechanism of release of the drug from the MDG matrix was found to be following the Korsmeyer-Peppas model. However, the diffusional release exponent (n) value lies below 0.5 demonstrating that the mechanism controlling the drug release is the Fickian diffusion.
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•The effect of processing parameters on the synthesis of GO were studied.•Freeze drying method is compared to the vacuum heating method for drying GO slurry.•Effect of un-reacted ...graphite on the thermal stability of GO is studied and the as-prepared GO used as adsorbent for lead ions.•A maximum adsorption of 120mg/g took place at initial concentration of 60mg/L Pb2+.•Kinetics data were well fitted to the pseudo-second-order kinetic model suggested that the adsorption is a chemical controlling process.
Lead (Pb) ion is a heavy metal ion contaminant in geochemical systems, and has non-repairable harmful effects due to their high toxicity. They create severe threats to human health and ecological balance. Therefore, it is highly needed to remove Pb ions from contaminated water/aqueous media. In this study, graphene oxides (GOs) were prepared using “Hummers” and “improved” methods for studying the effect of processing parameters on the as-prepared GO. The processing parameters such as purification and drying process; and the effect of un-reacted graphite flakes (UGFs) on the thermal stability of GO were investigated. The as-prepared GOs were characterized through X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and Raman spectroscopy. Further, we applied the as-prepared GO for the removal of Pb ions (Pb2+) from aqueous solution. The adsorption measurements were conducted through atomic absorption spectroscopy (AAS). The batch adsorption experiments were carried out to study the effect of initial concentration, contact time, and temperature on the adsorption of Pb2+ from aqueous solution onto the GO. It was found that the Pb2+ adsorption on GO increased with increase in the initial concentration of Pb2+. A maximum adsorption of 120mg/g took place at initial concentration of 60mg/L Pb2+. The adsorption studies recorded a relatively rapid uptake of Pb2+ by GO and followed pseudo-second-order kinetic model. The results indicated a significant potential of GO as an adsorbent for Pb2+ removal.
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