Electrophoretically deposited nano-structured polyaniline film for glucose sensing

Electrophoretically deposited nano-structured polyaniline (NS-PANI) film has been utilized for fabrication of glucose biosensor by covalent immobilization of glucose oxidase (GOx) using N-ethyl-N-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide chemistry. This GOx/NS-PANI/ITO bioelectrode has been characterized using scanning electron microscopy, FT-IR, UV–Visible spectroscopy and differential pulse voltammetry (DPV) techniques. The response studies carried out on GOx/NS-PANI/ITO bioelectrode using DPV and photometric studies reveal linearity up to 400 mgdL− 1 with sensitivity as 1.05 × 10− 4 mA mg− 1 dL and 3.887 × 10− 5 Abs mg− 1 dL, respectively. The lower value of Michaelis–Menten constant obtained for immobilized GOx (2.1 mM) compared with that of free GOx (5.85 mM) suggests high affinity of enzyme to this matrix

Functional Nanomaterials for Electronics, Optoelectronics, and Bioelectronics

With the miniaturization of electronic devices and advances in nanomaterial research and production, the application of functional nanomaterials is at the forefront of scientific and industrial attention. The use of nanomaterials on their own, or as part of a hybrid structure, allows new properties to be exploited in the areas of electronics, optoelectronics and photonics, and in bioelectronics. Recent advances in carbon nanomaterials, such as nanotubes and graphene, as well as other 2D layered materials, in nanostructured organic conducting polymers and in metal nanoparticles have broadened the scope of nanomaterials towards innovation in electronic and bioelectronic devices. This innovation has the potential to develop new consumer electronics, energy generation and storage technologies, and information communications and technology and in the areas of medical diagnosis and treatment

Polyaniline/Single-Walled Carbon Nanotubes Composite Based Triglyceride Biosensor

Nanocomposite film comprising of polyaniline (PANI) and single walled carbon nanotubes (SWCNT) has been fabricated onto indium-tin-oxide (ITO) coated glass plate using electrophoretic technique. Co-immobilization of glycerol dehydrogenase (GDH) and lipase (LIP) has been done via N-ethyl-N′-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide chemistry to explore its application for triglyceride (tributyrin) sensing. Response studies have been done using linear sweep voltammetry revealing that LIP-GDH/PANI-SWCNT-TB/ITO bioelectrode can detect tributyrin in the range of 50 to 400 mg dL−1 with low Michaelis–Menten constant of 1.138 mM, improved response time of 12 s, high sensitivity as 4.28×10−4 mA mg−1 dL and storage stability of about 13 weeks

Polyaniline–carbon nanotube composite film for cholesterol biosensor

Nanocomposite film composed of polyaniline (PANI) and multiwalled carbon nanotubes (MWCNT), prepared electrophoretically onto indium tin oxide (ITO)-coated glass plate, was used for covalent immobilization of cholesterol oxidase (ChOx) via N-ethyl-N'-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) chemistry. Results of linear sweep voltammetric measurements reveal that ChOx/PANI-MWCNT/ITO bioelectrode can detect cholesterol in the range of 1.29 to 12.93 mM with high sensitivity of 6800 nA mM(-1) and a fast response time of 10 s. Photometric studies for ChOx/PANI-MWCNT/ITO bioelectrode indicate that it is thermally stable LIP to 45 degrees C and has a shelf life of approximately 12 weeks when stored at 4 degrees C. The results of these studies have implications for the application of this interesting matrix (PANI-MWCNT) toward the development of other biosensors

Zirconia grafted carbon nanotubes based biosensor for M. Tuberculosis detection

Zirconia (ZrO2) grafted multiwalled carbon nanotubes (CNTs) (crystallite size of ZrO2 ∼ 28.63 nm), obtained via isothermal hydrolysis of zirconium oxychloride in presence of CNT, have been electrophoretically deposited onto indium-tin-oxide (ITO) coated glass plate. High resolution electron microscopic investigations reveal assemblage of the ZrO2 nanostructure inside and around CNT cavities. Electrochemical impedance spectroscopic studies indicate ∼3.5 fold enhancement in charge transfer behaviour of NanoZrO2-CNT/ITO electrode compared to that of NanoZrO2/ITO electrode. Considering the synergy between biocompatible ZrO2 and electrochemically superior CNT, this nanobiocomposite has been explored to develop an impedimetric nucleic acid biosensor for M. Tuberculosis detection

Preparation, characterization and application of polyaniline nanospheres to biosensing

Polyaniline nanospheres (PANI-NS) prepared by morphological transformation of micelle polymerized camphorsulfonic acid (CSA) doped polyaniline nanotubes (PANI-NT) in the presence of ethylene glycol (EG) have been characterized by X-ray diffraction, atomic force microscopy, transmission electron microscopy, scanning electron microscopy, Fourier transform infra-red and UV-Visible spectroscopy. A PANI-NS (60–80 nm) film deposited onto an indium-tin-oxide (ITO) coated glass plate by the solution casting method has been utilized for covalent immobilization of biomolecules (cholesterol oxidase (ChOx)) viaN-ethyl-N′-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) chemistry for fabrication of a cholesterol biosensor. The ChOx/PANI-NS/ITO bioelectrode detects cholesterol in the concentration range of 25 to 500 mg dL−1 with sensitivity of 1.3 × 10−3 mA mg−1 dL and regression coefficient of 0.98. Further, this PANI-NS based bioelectrode shows fast response time (10 s), low Michaelis–Menten constant (2.5 mM) and shelf-life of 12 weeks. The spherical nanostructure observed in the final morphology of the PANI-NS film is attributed to hydrogen bonding interactions between PANI-NT and EG

Anomalous electron transport in metal/carbon multijunction devices by engineering of the carbon thickness and selecting metal layer

A longstanding concern in the research of amorphous carbon films is their poor electrical conductivity at room temperature which constitutes a major barrier for the development of cost effective electronic and optoelectronic devices. Here, we propose metal/carbon hybrid multijunction devices as a promising facile way to overcome room temperature electron transport issues in amorphous carbon films. By the tuning of carbon thickness and swapping metal layers, we observe giant (upto similar to 7 orders) reduction of electrical resistance in metal/carbon multijunction devices with respect to monolithic amorphous carbon device. We engineer the maximum current (electrical resistance) from about 10(-7) to 10(-3) A (similar to 10(7) to 10(3) Omega) in metal (Cu or Ti)/carbon hybrid multijunction devices with a total number of 10 junctions. The introduction of thin metal layers breaks the continuity of relatively higher resistance carbon layer as well as promotes the nanostructuring of carbon. These contribute to low electrical resistance of metal/carbon hybrid multijunction devices, with respect to monolithic carbon device, which is further reduced by decreasing the thickness of carbon layers. We also propose and discuss equivalent circuit model to explain electrical resistance in monolithic carbon and metal/carbon multijunction devices. Cu/carbon multijunction devices display relatively better electrical transport than Ti/carbon devices owing to low affinity of Cu with carbon that restricts carbide formation. We also observe that in metal/carbon multijunction devices, the transport mechanism changes from Poole-Frenkel/Schottky model to the hopping model with a decrease in carbon thickness. Our approach opens a new route to develop carbon-based inexpensive electronic and optoelectronic devices

Polyaniline nanotubes for impedimetric triglyceride detection

Polyaniline nanotubes (PANI-NT) based film electrophoretically deposited onto indium–tin–oxide (ITO) coated glass plate has been utilized for covalent immobilization of lipase (LIP), via glutaraldehyde (Glu), for triglyceride detection using impedimetric technique. It is shown that fatty acid molecules produced during triglyceride hydrolysis result in change in charge transfer resistance (RCT) of PANI-NT film with varying triglyceride concentration. LIP/Glu/PANI-NT/ITO bioelectrode has linearity as 25–300 mg dL−1, sensitivity as 2.59 × 10−3 KΩ−1 mg−1 dL, response time as 20 s and regression coefficient as 0.99. A low value of apparent Michaelis–Menten constant (∼0.62 mM) indicates high enzyme affinity to tributyrin. The LIP/Glu/PANI-NT/ITO bioelectrode has been utilized to estimate triglyceride in serum samples