Reza Saber

A novel antibody–antigen based impedimetric immunosensor for low level detection of HER2 in serum samples of breast cancer patients via modification of a gold nanoparticles decorated multiwall carbon nanotube-ionic liquid electrode

A highly sensitive impedimetric immunosensor based on a gold nanoparticles/multiwall carbon nanotube-ionic liquid electrode (AuNPs/MW-CILE) was developed for the determination of human epidermal growth factor receptor 2 (HER2). Gold nanoparticles were used to enhance the extent of immobilization and to retain the immunoactivity of the antibody Herceptin on the electrode. Cyclic voltammetry and electrochemical impedance spectroscopy were employed for characterization of various layers coated onto the AuNPs/MW-CILE. The impedance measurements at different steps were based on the charge transfer kinetics of the [Fe(CN)6](3-/4-) redox pair. The immobilization of antibody and the corresponding antigen-antibody interaction at the electrode surface altered the interfacial electron transfer. The interactions of antibody with various concentrations of antigen were also monitored via the change of impedance response. The results showed that the charge transfer resistance increases linearly with increasing concentrations of HER2 antigen. The linear range and limit of detection were found as 10-110 ng mL(-1) and 7.4 ng mL(-1), respectively. The sensitivity and specificity of the immunosensor were validated. The results showed that the prepared immunosensor is a useful tool for screening of trace amounts of HER2 in serum samples of breast cancer patients.

Performance of electrodes synthesized with polyacrylonitrile-based carbon nanofibers for application in electrochemical sensors and biosensors

The purpose of this work was to investigate the performance of electrodes synthesized with Polyacrylonitrile-based carbon nanofibers (PAN-based CNFs). The homogenous PAN solutions with different concentrations were prepared and electrospun to acquire PAN nanofibers and then CNFs were fabricated by heat treatment. The effective parameters for the production of electrospun CNF electrode were investigated. Scanning electron microscopy (SEM) was used to characterize electrospun nanofibers. Cyclic voltammetry was applied to investigate the changes of behavior of electrospun CNF electrodes with different diameters. The structure of CNFs was also evaluated via X-ray diffraction (XRD) and Raman spectroscopy. The results exhibited that diameter of nanofibers reduced with decreasing polymer concentration and applied voltage and increasing tip-to-collector distance, while feeding rate did not have significant effect on nanofiber diameter. The investigations of electrochemical behavior also demonstrated that cyclic voltammetric response improved as diameter of CNFs electrode decreased.

Multiwall carbon nanotube-ionic liquid electrode modified with gold nanoparticles as a base for preparation of a novel impedimetric immunosensor for low level detection of human serum albumin in biological fluids.

A highly sensitive ionic liquid-multiwall carbon nanotube based impedimetric immunosensor modified with gold nanoparticles (GNPs) was developed for the determination of human serum albumin (HSA). The antigen and antibody models used were HSA and activated anti-HSA, respectively. GNPs were electrodeposited on the multiwall based carbon ionic liquid electrode (MW-CILE) surface and then colloidal GNPs were coated through the thiol groups of 1,6-hexanedithiol (HDT) monolayer as a cross linker. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were employed for characterization of the various layers coated onto the electrode. The electron transfer resistance (Ret) of the antibody-modified electrode changed linearly with the concentration of HSA. The linear range and limit of detection were 0.1-100μgmL(-1) and 15.4ngmL(-1), respectively. The sensitivity and specificity of the immunosensor were validated using human urine and human serum samples. The results showed that the prepared immunosensor is a useful tool for screening trace amounts of HSA in the biological fluids of proteinuria and diabetics patients, in clinical laboratories.

Parameters affecting carbon nanofiber electrodes for measurement of cathodic current in electrochemical sensors: an investigation using artificial neural network

The aim of this work was to investigate the effective parameters for predicting the cathodic current in a polyacrylonitrile-based carbon nanofiber (CNF) electrode using an artificial neural network (ANN) method. The various factors including CNF diameter, CNF layer thickness, electrodeposition time of Pt on the CNF electrode, and pH of a phosphate buffer solution (PBS) containing K3Fe (CN)6 were designed to investigate the cathodic current of the CNF electrode. The different samples of the electrodes were fabricated as training and testing data-sets for ANN modeling. The best network had one hidden layer with 10 nodes in the layer. The mean squared error (MSE) and linear regression (R) between the observed and predicted cathodic current were 0.0763 and 0.9563, respectively, confirming the performance of the ANN. The obtained results using cyclic voltammetry (CV) exhibited that the cathodic current improves with decreasing CNF diameter, CNF layer thickness, electrodeposition time of Pt on the CNF electrode and solution pH.

A high sensitive visible light-driven photoelectrochemical aptasensor for shrimp allergen tropomyosin detection using graphitic carbon nitride-TiO2 nanocomposite

Herein, for the first time a visible-light-driven photoelectrochemical (PEC) aptasensor for shrimp tropomyosin determination was fabricated by using graphitic carbon nitride (g-C3N4) and titanium dioxide (TiO2) as photoactive nanomaterials, ascorbic acid (AA) as electron donor and ruthenium (III) hexaammine (Ru(NH3)63+) as signal enhancer. The surface of an ITO electrode was first modified with g-C3N4, TiO2, and polyethyleneimine (PEI) and then the amine terminal aptamerTROP probe was attached to PEI by the use of glutaraldehyde (GA) as cross-linker. After that, Ru(NH3)63+ was adsorbed on aptamer to enhance the photocurrent signal. The principle of proposed PEC aptasensor is based on the formation of a selective complex between tropomyosin and immobilized aptamerTROP probe on the surface of ITO/g-C3N4-TiO2/PEI/aptamerTROP-Ru(NH3)6+3. After the incubation of tropomyosin with TROP aptamer probe, the photocurrent signal decreased due to releasing adsorbed Ru(NH3)63+ on aptamer and preventing AA from scavenging photogenerated holes to the photoactive modified electrode. Under the optimized conditions, the fabricated PEC aptasensor was used for the determination of shrimp tropomyosin in the concentration range of 1-400ngmL-1 with a limit of detection of 0.23ngmL-1. The proposed PEC aptasensor exhibited high selectivity, sensitivity, and good stability.

Optimizing parameters on alignment of PCL/PGA nanofibrous scaffold: An artificial neural networks approach

This paper proposes an artificial neural networks approach to finding the effects of electrospinning parameters on alignment of poly(ɛ-caprolactone)/poly(glycolic acid) blend nanofibers. Four electrospinning parameters, namely total polymer concentration, working distance, drum speed and applied voltage were considered as input and the standard deviation of the angles of nanofibers, introducing fibers alignments, as the output of the model. The results demonstrated that drum speed and applied voltage are two critical factors influencing nanofibers alignment, however their effect are entirely interdependent. Their effects also are not independent of other electrospinning parameters. In obtaining aligned electrospun nanofibers, the concentration and working distance can also be effective. In vitro cell culture study on random and aligned nanofibers showed directional growth of cells on aligned fibers.

A highly sensitive electrochemical sensor based on gold nanoparticles/multiwall carbon nanotubes-modified glassy carbon electrode for selective determination of traces of atenolol

In the present study, the electrochemical oxidation of atenolol (ATN) at gold nanoparticles (GNPs)/multiwall carbon nanotubes (MWCNTs)-modified glassy carbon electrode (GCE) was studied using cyclic voltammetry, differential pulse voltammetry and chronoamperometry. The synergetic effects of GNPs and MWCNTs highly improved electrochemical response and sensitivity of the sensor. The effect of experimental parameters, including amount of MWCNTs, GNPs, electrodeposition time, solution pH and scan rate on the sensor response, was evaluated. Under optimum experimental conditions, the respective linear calibration range, detection limit and sensitivity of the sensor were obtained as 1–60 μM, 0.5 μM and 350 nA μM−1 for differential pulse voltammetry and 0.1–1 μM, 59 nM and 4.405 μA μM−1 for chronoamperometry. The proposed sensor was successfully applied to the determination of atenolol in pharmaceutical samples, human urine and blood serum as real samples. The method was also applied to monitor ATN in urine samples of a dosage-received volunteer. Satisfactory recoveries of analyte from samples clearly revealed that the proposed sensor is well applicable to clinical analysis, quality control and a routine determination of drugs in pharmaceutical formulations.

Graphene/cobalt nanocarrier for hyperthermia therapy and MRI diagnosis

Graphene/cobalt nanocomposites are promising materials for theranostic nanomedicine applications, which are defined as the ability to diagnose, provide targeted therapy and monitor the response to the therapy. In this study, the composites were synthesized via chemical method, using graphene oxide as the source material and assembling cobalt nanoparticles of 15nm over the surface of graphene sheets. Various characterization techniques were then employed to reveal the morphology, size and structure of the nanocomposites, such as X-ray diffraction analysis, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, high resolution transmission electron microscopy and ultraviolet visible spectroscopy. Using ion-coupled plasma optical emission spectroscopy, cobalt concentration in the nanocomposites was found to be 80%. In addition, cytotoxicity of graphene/cobalt nanocomposites were evaluated using 3-[4,5-dimethylthiazol-2yl]-2,5-diphenyltetrazolium bromide or MTT assay. MTT viability assay exhibited biocompatibility to L929 mouse fibroblasts cells, under a high dose of 100μg/mL over 24h. Hyperthermia results showed the superior conversion of electromagnetic energy into heat at 350kHz frequency for 0.01 and 0.005g/L of the nanocomposites solution. The measured heat generation and energy transfer results were anticipated by the finite element analysis, conducted for the 3D structure. Magnetic resonance imaging characteristics also showed that negatively charge graphene/cobalt nanocomposites are suitable for T1-weighted imaging.

Chimeric Self-assembling Nanofiber Containing Bone Marrow Homing Peptide’s Motif Induces Motor Neuron Recovery in Animal Model of Chronic Spinal Cord Injury; an In Vitro and In Vivo Investigation

To date, spinal cord injury (SCI) has remained an incurable disaster. The use of self-assembling peptide nanofiber containing bioactive motifs such as bone marrow homing peptide (BMHP1) as an injectable scaffold in spinal cord regeneration has been suggested. Human endometrial-derived stromal cells (hEnSCs) have been approved by the FDA for clinical application. In this regard, we were interested in investigating the role of BMHP1 in hEnSCs’ neural differentiation in vitro and evaluating the supportive effects of this scaffold in rat model of chronic SCI. 1,1-Diphenyl-2-picryl-hydrazyl (DPPH), lactate dehydrogenase (LDH) release, 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) assay, real-time PCR, and immunocyotochemistry (ICC) were performed as a biocompatibility and neural differentiation evaluations on neuron-like hEnSC-derived cells encapsulated into nanofiber. Nanofiber was implanted into rats and followed by behavioral test, Nissl, luxol fast blue (LFB) staining and immunohistostaining (IHC). Results indicated that cell membrane of neuroblastoma cells were more sensitive than hEnSCs to concentration of proton and cell proliferation decreased with increase of concentration. This effect might be related to oxygen tension and elastic modules of scaffold. -BMHP1 nanofiber induced neural differentiation in hEnSC and decreased GFAP gene and protein as a marker of reactive astrocytes in vitro and in vivo. A reason for this finding might be related to the role of spacer number in induction of mechano-transduction signals. The presented study revealed the chimeric BMHP1 nanofiber induced higher axon regeneration and myelniation around the cavity and motor neuron function was encouraged to improve with less inflammatory response following SCI in rats. These effects were possibly due to nanostructured topography and mechano-transduction signals derived from hydrogel at low concentration.

Effect of gold nanoparticles on photodynamic efficiency of 5-aminolevolenic acid photosensitiser in epidermal carcinoma cell line: an in vitro study

In the recent years, enhanced functionality of treatment systems based on nanostructures has attracted a lot of interest. Photodynamic therapy (PDT) is one such treatment method. Here, the authors report the results of the investigations on synthesis and characterisation of gold nanoparticles (GNPs) and their application in PDT along with 5-aminolevolenic acid (5-ALA) (as photosensitiser) with no conjugation. Three sizes of GNPs were synthesised and their cytotoxicity was investigated by using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay on epidermal carcinoma cell line. The results showed that the PDT efficiency of ALA increased in presence of GNPs. This effect was more considerable for 4 nm particles.