Highly sensitive biofunctionalized nickel oxide nanowires for nanobiosensing applications

We report results of the studies relating to the fabrication of nickel oxide nanowires (NwNiOs) with an enhanced aspect ratio of similar to 100 for biosensing applications. Anti Vibrio cholerae monoclonal antibodies were used to functionalize the nickel oxide nanowire (20-80 nm) surfaces fabricated on indium tin oxide coated glass plate for Vibrio cholerae detection. The results of the impedance response studies conducted using this immunoelectrode as a function of the Vibrio cholerae concentration revealed a detection range of 37-350 ng ml(-1) and a low detection limit of 0.553 ng ml(-1) using the 3 sigma(b)/m criteria. The high sensitivity (11.12 Omega (ng ml(-1))(-1) cm(-2)) of this fabricated sensor is attributed to the excellent electronic properties of NiO nanowires which facilitate the efficient transfer of electrons between the electrode and the antibody molecules through electron channeling effects. Besides this, the nanostructured NiO nanowire based immunosensor exhibits interesting supercapacitive behaviour towards the detection of CT. This immunosensor showed values of association constant (K-a) of 4.5 x 10(7) ng ml(-1) and dissociation constant (K-d) of 2.22 x 10(-6) ng ml(-1)

Dielectric behaviour of neutrophil gelatinase associated lipocalin detected by alpha relaxation process

We have investigated alpha () relaxation process and its temperature evolution in electrical double layer (EDL) around neutrophil gelatinase-associated lipocalin (NGAL), anti-lipocalin2 (anti-LCN-2) and their conjugate in phosphate buffer. The dielectric permittivity (20Hz to 1MHz) of -relaxation process for LCN-2 and anti-LCN-2 shows variation with temperature. This happens due to unfolding of various microstates of protein at measured temperature intervals. The DSC thermograms of LCN-2, anti-LCN-2 and their conjugate predict that the multiple unfolding domains are parallel to the shifts in real dielectric permittivity at a particular temperature

Highly Sensitive Biofunctionalized Mesoporous Electrospun TiO2 Nanofiber Based Interface for Biosensing

The surface modified and aligned mesoporous anatase titania nanofiber mats (TiO2-NF) have been fabricated by electrospinning for esterified cholesterol detection by electrochemical technique. The electrospinning and porosity of mesoporous TiO2-NF were controlled by use of polyvinylpyrrolidone (PVP) as a sacrificial carrier polymer in the titanium isopropoxide precursor. The mesoporous TiO2-NF of diameters ranging from 30 to 60 nm were obtained by calcination at 470 degrees C and partially aligned on a rotating drum collector. The functional groups such as -COOH, -CHO etc. were introduced on TiO2-NF surface via oxygen plasma treatment making the surface hydrophilic. Cholesterol esterase (ChEt) and cholesterol oxidase (ChOx) were covalently immobilized on the plasma treated surface of NF (cTiO(2)-NF) via N-ethyl-N0(3-dimethylaminopropyl carbodiimide) and N-hydroxysuccinimide (EDC-NHS) chemistry. The high mesoporosity (similar to 61%) of the fibrous film allowed enhanced loading of the enzyme molecules in the TiO2-NF mat. The ChEt-ChOx/cTiO(2)-NF-based bioelectrode was used to detect esterified cholesterol using electrochemical technique. The high aspect ratio, surface area of aligned TiO2-NF showed excellent voltammetric and catalytic response resulting in improved detection limit (0.49 mM). The results of response studies of this biosensor show excellent sensitivity (181.6 mu A/mg dL(-1)/cm(2)) and rapid detection (20 s). This proposed strategy of biomolecule detection is thus a promising platform for the development of miniaturized device for biosensing applications

Protein-Conjugated Quantum Dots Interface: Binding Kinetics and Label-Free Lipid Detection

We propose a label-free biosensor platform to investigate the binding kinetics using antigen-antibody interaction via electrochemical and surface plasmon resonance (SPR) techniques. The L-cysteine in situ capped cadmium sulfide (CdS; size < 7 nm) quantum dots (QDs) self-assembled on gold (Au) coated glass electrode have been covalently functionalized with apolipoprotein B-100 antibodies (AAB). This protein conjugated QDs-based electrode (AAB/CysCdS/Au) has been used to detect lipid (low density lipoprotein, LDL) biomolecules. The electrochemical impedimetric response of the AAB/CysCdS/Au biosensor shows higher sensitivity (32.8 k Omega mu M-1/cm(2)) in the detection range, 5-120 mg/dL. Besides this, efforts have been made to investigate the kinetics of antigen-antibody interactions at the CysCdS surface. The label-free SPR response of AAB/CysCdS/Au biosensor exhibits highly specific interaction to protein (LDL) with association constant of 33.4 kM(-1) s(-1) indicating higher affinity toward LDL biomolecules and a dissociation constant of 0.896 ms(-1). The results of these studies prove the efficacy of the CysCdS-Au platform as a high throughput compact biosensing device for investigating biomolecular interactions

Chitosan-Modified Carbon Nanotubes-Based Platform for Low-Density Lipoprotein Detection

We have fabricated an immunosensor based on carbon nanotubes and chitosan (CNT-CH) composite for detection of low density lipoprotein (LDL) molecules via electrochemical impedance technique. The CNT-CH composite deposited on indium tin oxide (ITO)-coated glass electrode has been used to covalently interact with anti-apolipoprotein B (antibody: AAB) via a co-entrapment method. The biofunctionalization of AAB on carboxylated CNT-CH surface has been confirmed by Fourier transform infrared spectroscopic and electron microscopic studies. The covalent functionalization of antibody on transducer surface reveals higher stability and reproducibility of the fabricated immunosensor. Electrochemical properties of the AAB/CNT-CH/ITO electrode have been investigated using cyclic voltammetric and impedimetric techniques. The impedimetric response of the AAB/CNT-CH/ITO immunoelectrode shows a high sensitivity of 0.953 a"broken vertical bar/(mg/dL)/cm(2) in a detection range of 0-120 mg/dL and low detection limit of 12.5 mg/dL with a regression coefficient of 0.996. The observed low value of association constant (0.34 M(-1)s(-1)) indicates high affinity of AAB/CNT-CH/ITO immunoelectrode towards LDL molecules. This fabricated immunosensor allows quantitative estimation of LDL concentration with distinguishable variation in the impedance signal

Nanostructured magnesium oxide biosensing platform for cholera detection

We report fabrication of highly crystalline nanostructured magnesium oxide (NanoMgO, size >30 nm) film electrophoretically deposited onto indium-tin-oxide (ITO) glass substrate for Vibrio cholerae detection. The single stranded deoxyribonucleic acid (ssDNA) probe, consisting of 23 bases (O1 gene sequence) immobilized onto NanoMgO/ITO electrode surface, has been characterized using electrochemical, Fourier Transform-Infra Red, and UltraViolet-visible spectroscopic techniques. The hybridization studies of ssDNA/NanoMgO/ITO bioelectrode with fragmented target DNA conducted using differential pulse voltammetry reveal sensitivity as 16.80 nA/ng/cm(2), response time of 3 s, linearity as 100-500 ng/mu L, and stability of about 120 days

Diagnostic and prognostic role of magnetic resonance imaging in cases of moderate to severe traumatic brain injury

Moderate to severe traumatic brain injury (TBI) remains a leading cause of death and disability worldwide. Timely diagnosis and accurate prognostication play a key role in informed clinical decision-making. Though magnetic resonance imaging (MRI) is a superior anatomical scan compared to computerized tomography (CT), the latter remains the current investigation of choice in the clinical setting of TBI due to some of the former’s inherent deficiencies in imaging bone/blood, limited access, cost, etc. Nevertheless, the fact that MRI is a valuable adjunct in evaluating the TBI patients with clinical findings disproportionate to the CT scan substantiates its possible complementary/supplementary diagnostic and prognostic role in TBI. MRI scan is ideally placed on demonstrating the shear/diffuse axonal injury (DAI), non-haemorrhagic intraparenchymal lesions, and brain stem lesions poorly delineated by a CT scan. The currently available literature demonstrates that DAI and caudal brainstem lesions are indicators of poorer outcomes. However, the prognostic value of MRI, in addition to that of CT, remains an area of active investigation. We have tried to present the evidence-based use of MRI in moderate to severe TBI. Advances in newer MRI sequences like susceptibility-weighted imaging (SWI), diffusion tensor imaging (DTI), functional MRI (fMRI), and magnetic encephalography (MEG) have the potential to revolutionize the current role of MRI in TBI. 

Highly Sensitive Biofunctionalized Mesoporous Electrospun TiO₂ Nanofiber Based Interface for Biosensing

The surface modified and aligned mesoporous anatase titania nanofiber mats (TiO₂–NF) have been fabricated by electrospinning for esterified cholesterol detection by electrochemical technique. The electrospinning and porosity of mesoporous TiO₂–NF were controlled by use of polyvinylpyrrolidone (PVP) as a sacrificial carrier polymer in the titanium isopropoxide precursor. The mesoporous TiO₂–NF of diameters ranging from 30 to 60 nm were obtained by calcination at 470 °C and partially aligned on a rotating drum collector. The functional groups such as −COOH, −CHO etc. were introduced on TiO₂–NF surface via oxygen plasma treatment making the surface hydrophilic. Cholesterol esterase (ChEt) and cholesterol oxidase (ChOx) were covalently immobilized on the plasma treated surface of NF (cTiO₂–NF) via <i>N</i>-ethyl-<i>N</i>0-(3-dimethylaminopropyl carbodiimide) and <i>N</i>-hydroxysuccinimide (EDC-NHS) chemistry. The high mesoporosity (∼61%) of the fibrous film allowed enhanced loading of the enzyme molecules in the TiO₂–NF mat. The ChEt-ChOx/cTiO₂–NF-based bioelectrode was used to detect esterified cholesterol using electrochemical technique. The high aspect ratio, surface area of aligned TiO₂–NF showed excellent voltammetric and catalytic response resulting in improved detection limit (0.49 mM). The results of response studies of this biosensor show excellent sensitivity (181.6 μA/mg dL^–1/cm²) and rapid detection (20 s). This proposed strategy of biomolecule detection is thus a promising platform for the development of miniaturized device for biosensing applications

A surface functionalized nanoporous titania. integrated microfluidic biochip

We present a novel and efficient nanoporous microfluidic biochip consisting of a functionalized chitosan/anatase titanium dioxide nanoparticles (antTiO(2)-CH) electrode integrated in a polydimethylsiloxane (PDMS) microchannel assembly. The electrode surface can be enzyme functionalized depending on the application. We studied in detail cholesterol sensing using the cholesterol esterase (ChEt) and cholesterol oxidase (Ch0x) functionalized chitosan supported mesoporous antTiO(2)-CH microfluidic electrode. The available functional groups present in the nanoporous antTiO(2)-CH surface in this microfluidic biochip can play an important rote for enzyme functionalization, which has been quantified by the X-ray photoelectron spectroscopic technique. The Brunauer-Emmett-Teller (BET) studies are used to quantify the specific surface area and nanopore size distribution of titania nanoparticles with and without chitosan. Point defects in antTiO(2) can increase the heterogeneous electron transfer constant between the electrode and enzyme active sites, resulting in improved electrochemical behaviour of the microfluidic biochip. The impedimetric response of the nanoporous microfluidic biochip (ChEt-ChOx/antTiO(2)-CH) shows a high sensitivity of 6.77 k Omega (mg dl(-1))(-1) in the range of 2-500 mg dl(-1), a low detection limit of 0.2 mg dl(-1), a low Michaelis-Menten constant of 1.3 mg dl(-1) and a high selectivity. This impedimetric microsystem has enormous potential for clinical diagnostics application

Protein–Conjugated Quantum Dots Interface: Binding Kinetics and Label-Free Lipid Detection

We propose a label-free biosensor platform to investigate the binding kinetics using antigen–antibody interaction via electrochemical and surface plasmon resonance (SPR) techniques. The l-cysteine in situ capped cadmium sulfide (CdS; size < 7 nm) quantum dots (QDs) self-assembled on gold (Au) coated glass electrode have been covalently functionalized with apolipoprotein B-100 antibodies (AAB). This protein conjugated QDs-based electrode (AAB/CysCdS/Au) has been used to detect lipid (low density lipoprotein, LDL) biomolecules. The electrochemical impedimetric response of the AAB/CysCdS/Au biosensor shows higher sensitivity (32.8 kΩ μM^–1/cm²) in the detection range, 5–120 mg/dL. Besides this, efforts have been made to investigate the kinetics of antigen–antibody interactions at the CysCdS surface. The label-free SPR response of AAB/CysCdS/Au biosensor exhibits highly specific interaction to protein (LDL) with association constant of 33.4 kM^–1 s^–1 indicating higher affinity toward LDL biomolecules and a dissociation constant of 0.896 ms^–1. The results of these studies prove the efficacy of the CysCdS-Au platform as a high throughput compact biosensing device for investigating biomolecular interactions