Entity

Time filter

Source Type


Gholivand M.-B.,Razi University | Jalalvand A.R.,Razi University | Jalalvand A.R.,Laboratorio Of Desarrollo Analitico Y Quimiometria Ladaq | Goicoechea H.C.,Laboratorio Of Desarrollo Analitico Y Quimiometria Ladaq
Electrochimica Acta | Year: 2014

A computationally designed impedimetric pregabalin (PGB) biosensor based on immobilization of bovine serum albumin (BSA) onto graphene/glassy carbon electrode (BSA/Gr/GCE) has been developed using initial characterization by computational methods and complementing them by experimental observations. Computational results showed that the BSA hydrophobically binds to Gr which is energetically favorable and leads to the spontaneous formation of the stable nanobiocomposite (BSA/Gr), and also showed that the interaction of PGB with BSA is mainly driven by hydrogen bonding and hydrophobic interactions. The interactions of BSA with Gr and PGB with BSA were also monitored by fluorescence and UVvis spectroscopic techniques, and their results were consistent with the computational results. The electrochemical properties of the fabricated composite electrodes were examined by cyclic voltammetry (CV) scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS) techniques. Besides complementing the computational studies, experimental results showed that the addition of Gr to the surface of the electrode facilitated the electron transfer reactions, and also showed that the presence of BSA inhibits the interfacial electron transfer in some extent due to the non-conductive properties of BSA. The presence of the PGB may form an electroinactive complex with BSA which decelerates the interfacial electron transfer leading to obvious faradaic impedance changes. The faradaic impedance responses were linearly related to PGB concentration between 10.0 nM and 280.0 nM and the limit of detection (LOD) was calculated to be 3.0 nM (3Sb/b). Finally, the proposed biosensor was successfully applied to determination of PGB in human serum samples. The results were satisfactory and comparable to those obtained by applying the reference method based on high performance liquid chromatography (HPLC). The results confirmed that the proposed biosensor has good sensitivity, selectivity, stability, repeatability, reproducibility, and regeneration ability for PGB determination. © 2014 Published by Elsevier Ltd.


Gholivand M.-B.,Razi University | Jalalvand A.R.,Razi University | Jalalvand A.R.,Laboratorio Of Desarrollo Analitico Y Quimiometria Ladaq | Goicoechea H.C.,Laboratorio Of Desarrollo Analitico Y Quimiometria Ladaq | Skov T.,Copenhagen University
Talanta | Year: 2014

For the first time, an ultrasensitive impedimetric buprenorphine hydrochloride (BN) biosensor based on immobilization of bovine serum albumin (BSA) onto multi-walled carbon nanotubes (MWCNTs)/glassy carbon electrode (BSA/MWCNTs/GCE) has been developed using initial characterization by computational methods and complementing them by experimental observations. Computational results showed that the BSA hydrophobically binds to MWCNTs which is energetically favorable and leads to spontaneous formation of the stable BSA/MWCNTs nanobiocomposite (bioconjugate). Computational results also showed that the interaction of BN with BSA is mainly driven by hydrophobic interactions. The interactions of BSA with MWCNTs and BN with BSA were also monitored by fluorescence and UV-vis spectroscopic techniques, and their results were consistent with the computational results. Morphology and electrochemical properties of the fabricated composite electrodes were examined by scanning electron microscopy (SEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). Besides complementing the computational studies, experimental results showed that the addition of MWCNTs to the surface of the GCE greatly facilitated the electron transfer reactions, and also showed that the presence of BSA inhibits the interfacial electron transfer in some extent due to the non-conductive properties of BSA. On the other hand, the presence of BN may form an electroactive complex with BSA which accelerates the interfacial electron transfer and leads to obvious Faradaic impedance changes. The Faradaic impedance responses were linearly related to BN concentration between 5.0 nM and 72.0 nM and a limit of detection (LOD, 3Sb/b) of 1.5 nM was achieved. Finally, the proposed biosensor was successfully applied to determination of BN in urine samples of both healthy and addict volunteers. The results were satisfactory and comparable to those obtained by applying the reference method based on high performance liquid chromatography-ultraviolet detection (HPLC-UV). It is expected that the distinctive features of BSA/MWCNTs nanobiocomposite would make it potentially advantageous for a broad range of biosensing, and clinical applications. © 2014 Elsevier B.V.


Gholivand M.-B.,Razi University | Jalalvand A.R.,Razi University | Jalalvand A.R.,Laboratorio Of Desarrollo Analitico Y Quimiometria Ladaq | Goicoechea H.C.,Laboratorio Of Desarrollo Analitico Y Quimiometria Ladaq | And 2 more authors.
Talanta | Year: 2015

For the first time, interaction of vitamin B7 (VB7) with bovine serum albumin (BSA) was investigated with the aim of developing a method for the analysis of BSA. The interaction of VB7 with BSA was investigated by cyclic voltammetry (CV), linear sweep voltammetry (LSV), and differential pulse voltammetry (DPV) at a multi-walled carbon nanotubes-modified glassy carbon electrode (MWCNTs/GCE). The recorded electrochemical data was combined with UVvis and fluorescence (F) spectroscopic data into a row- and column-wise augmented matrix and resolved by multivariate curve resolution-alternating least squares (MCR-ALS) as an efficient chemometric tool, and this assisted in the further elucidation of the above interaction. Also, with aid of MCR-BANDS method, the absence of rotational ambiguity was verified in the obtained results and we confirmed that the obtained results were unambiguous and reliable. The binding of VB7 to BSA was also modeled by molecular docking methods. Excellent agreement was found between the experimental and computational results. The differences of DPV responses of VB7 in the absence and presence of BSA (ΔI) were found to be linearly related to BSA concentration between 0.5×10-9 mol L-1 and 35.0×10-9 mol L-1, and a limit of detection (LOD, 3Sb/b) of 0.22×10-9 mol L-1 was calculated. Finally, the DPV method was further applied to the determination of serum albumin (SA) in serum samples obtained from Holstein cows and the results were in good agreement with those obtained by a medical diagnostic laboratory whose method was based on traditional cellulose acetate electrophoresis. The MWCNTs/GCE showed enhanced electron transfer kinetics, large electroactive surface area, and was highly sensitive, selective, and stable towards SA determination. The satisfactory analytical performance of the proposed method would make it potentially advantageous for a broad range of biosensing and clinical applications. © 2014 Elsevier B.V.


Gholivand M.-B.,Razi University | Jalalvand A.R.,Razi University | Jalalvand A.R.,Laboratorio Of Desarrollo Analitico Y Quimiometria Ladaq | Goicoechea H.C.,Laboratorio Of Desarrollo Analitico Y Quimiometria Ladaq | And 3 more authors.
Talanta | Year: 2015

For the first time, an analytical methodology based on differential pulse voltammetry (DPV) at a glassy carbon electrode (GCE) and integration of three efficient strategies including variable selection based on ant colony optimization (ACO), mathematical pre-processing selection by genetic algorithm (GA), and sample selection (SS) through a distance-based procedure to improve partial least squares-1 (PLS-1, ACO-GA-SS-PLS-1) multivariate calibration (MVC) for the simultaneous determination of five opium alkaloids including morphine (MOP), noscapine (NOP), thebaine (TEB), codeine (COD), and papaverine (PAP) was used and validated. The baselines of the DPV signals were modeled as a smooth curve, using P-splines, a combination of B-splines and a discrete roughness penalty. After subtraction of the baseline we got a signal with a two-component probability density. One component was for the peaks and it was approximated by a uniform distribution on the potential axis. The other component was for the observed noise around the baseline. Some sources of bi-linearity deviation for electrochemical data were discussed and analyzed. The lack of bi-linearity was tackled by potential shift correction using correlation optimized warping (COW) algorithm. The MVC model was developed as a quinternary calibration model in a blank human serum sample (drug-free) provided by a healthy volunteer to regard the presence of a strong matrix effect which may be caused by the possible interferents present in the serum, and it was validated and tested with two independent sets of analytes mixtures in the blank and actual human serum samples, respectively. Fortunately, the proposed methodology was successful in simultaneous determination of MOP, NOP, TEB, COD, and PAP in both blank and actual human serum samples and its results were satisfactory comparable to those obtained by applying the reference method based on high performance liquid chromatography-ultraviolet detection (HPLC-UV). © 2014 Published by Elsevier B.V.


Kuligowski J.,University of Valencia | Galera M.M.,University of Almeria | Garcia M.D.G.,University of Almeria | Culzoni M.J.,Laboratorio Of Desarrollo Analitico Y Quimiometria Ladaq | And 4 more authors.
Talanta | Year: 2011

Multivariate science based calibration (SBC) has been applied to the resolution of overlapped peaks in liquid chromatography with diode array detection (LC-DAD). Complex river water samples spiked with 11 pharmaceutical substances resulted in poorly resolved chromatograms containing additional peaks from interfering matrix compounds and a change in the background absorbance due to the mobile phase gradient. Applying the present multivariate approach it was possible to resolve all 11 analytes from overlapping peaks, obtaining linear calibration lines (R2 > 0.96). Recovery percentages on spiked samples ranged between 74.6 and 113.5%, which are quite satisfactory taking into account the low concentration ranges considered to 1-7 μg L-1. © 2010 Elsevier B.V. All rights reserved.

Discover hidden collaborations