Publications by authors named "Mehdi Khodadadian"

9 Publications

  • Page 1 of 1

Multivariate Optimization of the Refolding Process of an Incorrectly Folded Fc-Fusion Protein in a Cell Culture Broth.

Curr Pharm Biotechnol 2020 ;21(3):226-235

Biopharmaceutical Research Center, AryoGen Pharmed Inc., Alborz University of Medical Sciences, Karaj, Iran.

Background: Protein misfolding is a common problem in large-scale production of recombinant proteins, which can significantly reduce the yield of the process.

Objective: In this work, we aimed at treating a cell culture broth containing high levels (>45%) of incorrectly folded Fc-fusion proteins by a simple redox buffer system in order to increase the proportion of the protein with correct conformation.

Methods: Multi-variable process optimization was firstly conducted at a small scale (25 mL), employing an experimental design methodology. After identifying the key variables using a resolution IV Fractional Factorial Design (FFD), the process was then optimized by the Central Composite Design (CCD).

Results: The optimal conditions for the refolding reaction were 340 mM Tris-base, 6.0 mM L-cysteine, 0.5 mM L-cystine, a buffer pH of 9.0, a reaction temperature of 8.5ºC and a reaction time of 24 h. Based on the treatment conditions obtained at a small scale, the process was further scaled up to 4500- L. The misfolded content was always less than 20%. The reaction can proceed well in the absence of chemical additives, such as chaotropic agents, aggregation suppressors, stabilizers and chelators.

Conclusion: The refolding process increases the fraction of active protein in the original broth reducing the burden on downstream purification steps markedly.
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http://dx.doi.org/10.2174/1389201020666191002144424DOI Listing
May 2020

Determination of residual poly diallyldimethylammonium chloride (pDADMAC) in monoclonal antibody formulations by size exclusion chromatography and evaporative light scattering detector.

Biologicals 2019 Jan 14;57:21-28. Epub 2018 Nov 14.

Biopharmaceutical Research Center, AryoGen Pharmed Inc., Alborz University of Medical Sciences, Karaj, Iran.

The cationic polyelectrolyte pDADMAC is widely used in biopharmaceutical industry as a flocculating agent to enhance clarification throughput and downstream filtration operations. Due to the possible toxicity, pDADMAC should be assessed for an acceptable residual level to ascertain the safety of the product to patients. The strong protein-polyelectrolyte interaction, however, can negatively affect sensitivity and accuracy of measurements. This paper reports on the application of size exclusion (SE) chromatography coupled to evaporative light scattering detector (ELSD) to the quantitative determination of pDADMAC in monoclonal antibody formulations and in process intermediates during downstream purification. The SE chromatography was performed under isocratic condition with a mobile phase consisting of 0.1% TFA in water (90%) and acetonitrile (10%) at a flow rate of 0.4 ml/min. A quantification limit (S/N = 10) of 0.85 ppm was achieved in sample matrix, which is sufficiently low for the trace analysis of this compound in protein-containing samples.
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http://dx.doi.org/10.1016/j.biologicals.2018.11.002DOI Listing
January 2019

Adsorptive Behavior and Voltammetric Determination of Hydralazine Hydrochloride at A Glassy Carbon Electrode Modified with Multiwalled Carbon Nanotubes.

Iran J Pharm Res 2017 ;16(4):1312-1319

Medical Biology Research Center, Kermanshah University of Medical Sciences, Kermanshah, Iran.

An electroanalytical method has been introduced for highly sensitive determination of hydralazine hydrochloride (Hy-HCl) based on its oxidation at a glassy carbon electrode modified with multiwalled carbon nanotubes (MWCNT/GCE). Studies showed that the electrochemical oxidation of Hy-HCl was accompanied by adsorption and highly sensitive responses could be achieved by adsorptive stripping voltammetry. The electrooxidation of Hy-HCl at MWCNT/GCE occurred at ~32 mV which was lower than that observed at bare GCE (~52 mV). The optimum working conditions for determination of the drug using differential-pulse adsorptive stripping voltammetry (DPAdSV) were established. The method exhibited linear responses to Hy-HCl in the concentration range 10-220 nM with a detection limit of 2.7 nM. The proposed method was successfully applied to the determination of this compound in pharmaceutical dosage forms.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5843295PMC
January 2017

Amperometric cholesterol biosensor based on the direct electrochemistry of cholesterol oxidase and catalase on a graphene/ionic liquid-modified glassy carbon electrode.

Biosens Bioelectron 2014 Mar 21;53:472-8. Epub 2013 Oct 21.

Department of Analytical Chemistry, Faculty of Chemistry, Razi University, Kermanshah, Iran. Electronic address:

Cholesterol oxidase (ChOx) and catalase (CAT) were co-immobilized on a graphene/ionic liquid-modified glassy carbon electrode (GR-IL/GCE) to develop a highly sensitive amperometric cholesterol biosensor. The H2O2 generated during the enzymatic reaction of ChOx with cholesterol could be reduced electrocatalytically by immobilized CAT to obtain a sensitive amperometric response to cholesterol. The direct electron transfer between enzymes and electrode surface was investigated by cyclic voltammetry. Both enzymes showed well-defined redox peaks with quasi-reversible behaviors. An excellent sensitivity of 4.163 mA mM(-1)cm(-2), a response time less than 6s, and a linear range of 0.25-215 μM (R(2)>0.99) have been observed for cholesterol determination using the proposed biosensor. The apparent Michaelis-Menten constant (KM(app)) was calculated to be 2.32 mM. The bienzymatic cholesterol biosensor showed good reproducibility (RSDs<5%) with minimal interference from the coexisting electroactive compounds such as ascorbic acid and uric acid. The CAT/ChOx/GR-IL/GCE showed excellent analytical performance for the determination of free cholesterol in human serum samples.
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http://dx.doi.org/10.1016/j.bios.2013.09.074DOI Listing
March 2014

Amperometric sensor based on a graphene/copper hexacyanoferrate nano-composite for highly sensitive electrocatalytic determination of captopril.

Mater Sci Eng C Mater Biol Appl 2013 Mar 10;33(2):774-81. Epub 2012 Nov 10.

Department of Analytical Chemistry, Faculty of Chemistry, Razi University, Kermanshah, Iran.

In this work, a bi-layer modified glassy carbon electrode (GCE) was prepared by depositing appropriate amounts of multilayered graphene (GR) on the surface of GCE, followed by electrodepositing copper hexacyanoferrate (CuHCF) nano-particles on the graphene layer. The combination of graphene and CuHCF considerably improved the current response of the GCE towards the oxidation of captopril. Studies showed that the best response of the modified electrode could be achieved within neutral pHs. At a fixed potential under hydrodynamic conditions (stirred solutions), the oxidation current is proportional to the captopril concentration and the calibration plots were linear over the concentration ranges of 0.2 to 5.8 μM and 5.8 to 480 μM. The detection limit of the method was 0.09 μM. The modified electrode was used for electrocatalytic determination of captopril in some real samples.
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http://dx.doi.org/10.1016/j.msec.2012.11.001DOI Listing
March 2013

Rationally designed molecularly imprinted polymers for selective extraction of methocarbamol from human plasma.

Talanta 2011 Sep 2;85(3):1680-8. Epub 2011 Jul 2.

Department of Analytical Chemistry, Faculty of Chemistry, Razi University, Kermanshah, Iran.

Molecularly imprinted polymers (MIPs) with high selectivity toward methocarbamol have been computationally designed and synthesized based on the general non-covalent molecular imprinting approach. A virtual library consisting of 18 functional monomers was built and possible interactions between the template and functional monomers were investigated using a semiempirical approach. The monomers with the highest binding scores were then considered for additional calculations using a more accurate quantum mechanical (QM) calculation exploiting the density functional theory (DFT) at B3LYP/6-31G(d,p) level. The cosmo polarizable continuum model (CPCM) was also used to simulate the polymerization solvent. On the basis of computational results, acrylic acid (AA) and tetrahydrofuran (THF) were found to be the best choices of functional monomer and polymerization solvent, respectively. MIPs were then synthesized by the precipitation polymerization method and used as selective adsorbents to develop a molecularly imprinted solid-phase extraction (MISPE) procedure before quantitative analysis. After MISPE the drug could be determined either by differential pulse voltammetry (DPV), on a glassy carbon electrode modified with multiwalled-carbon nanotubes (GC/MWNT), or high performance chromatography (HPLC) with UV detection. A comparative study between MISPE-DPV and MISPE-HPLC-UV was performed. The MISPE-DPV was more sensitive but both techniques showed similar accuracy and precision.
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http://dx.doi.org/10.1016/j.talanta.2011.06.066DOI Listing
September 2011

Computer-assisted design and synthesis of molecularly imprinted polymers for selective extraction of acetazolamide from human plasma prior to its voltammetric determination.

Talanta 2010 Jun 25;81(4-5):1446-53. Epub 2010 Feb 25.

Department of Chemistry, Faculty of Science, Razi University, Kermanshah, Iran.

Molecularly imprinted polymers (MIPs) were computationally designed and synthesized for the selective extraction of a carbonic anhydrase inhibitor, i.e. acetazolamide (ACZ), from human plasma. Density functional theory (DFT) calculations were performed to study the intermolecular interactions in the pre-polymerization mixture and to find a suitable functional monomer in MIP preparation. The interaction energies were corrected for the basis set superposition error (BSSE) using the counterpoise (CP) correction. The polymerization solvent was simulated by means of polarizable continuum model (PCM). It was found that acrylamide (AAM) is the best candidate to prepare MIPs. To confirm the results of theoretical calculations, three MIPs were synthesized with different functional monomers and evaluated using Langmuir-Freundlich (LF) isotherm. The results indicated that the most homogeneous MIP with the highest number of binding sites is the MIP prepared by AAM. This polymer was then used as a selective adsorbent to develop a molecularly imprinted solid-phase extraction procedure followed by differential pulse voltammetry (MISPE-DPV) for clean-up and determination of ACZ in human plasma.
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http://dx.doi.org/10.1016/j.talanta.2010.02.049DOI Listing
June 2010

Computer aided-molecular design and synthesis of a high selective molecularly imprinted polymer for solid-phase extraction of furosemide from human plasma.

Anal Chim Acta 2010 Jan 16;658(2):225-32. Epub 2009 Nov 16.

Department of Chemistry, Faculty of Science, Razi University, Kermanshah, Iran.

Highly selective molecularly imprinted polymers (MIPs) for solid-phase extraction and determination of furosemide in human plasma have been designed and prepared. In order to study the intermolecular interactions in the pre-polymerization mixture and to find a suitable functional monomer in MIP preparation, a computational approach was developed. It was based on the comparison of the binding energy of the complexes between the template and functional monomers. Having confirmed the results of computational method, three MIPs were synthesized with different functional monomers, i.e. acrylamide (AAM), 4-vinylpiridine (4-VP) and acrylonitrile (ACN), and then evaluated using Langmuir-Freundlich (LF) isotherm. Using the MIP prepared by AAM as functional monomer, a molecularly imprinted solid-phase extraction procedure followed by high performance liquid chromatography with ultraviolet detector (MISPE-HPLC-UV) was developed for selective extraction and determination of furosemide in human plasma. For the proposed MISPE-HPLC-UV method, the linearity between responses (peak area) and concentration was found over the range of 75-3500 ng mL(-1) with a linear regression coefficient (R(2)) of 0.997. The limit of detection (LOD) and quantification (LOQ) in plasma were 12.9 and 43.3 ng mL(-1), respectively.
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http://dx.doi.org/10.1016/j.aca.2009.11.019DOI Listing
January 2010

Novel platinum(II) selective membrane electrode based on 1,3-bis(2-cyanobenzene)triazene.

Talanta 2009 May 22;78(3):922-8. Epub 2009 Jan 22.

Department of Chemistry, Razi University, Kermanshah, Iran.

A plasticized poly (vinyl chloride) membrane electrode based on 1,3-bis(2-cyanobenzene)triazene (CBT) for highly selective determination of platinum(II) (in PtCl(4)(2-) form) is developed. The electrode showed a good Nernstian response (29.8+/-0.3 mV decade(-1)) over a wide concentration range (1.0 x 10(-6) to 1.0 x 10(-2)mol L(-1)). The limit of detection was 5.0 x 10(-7)mol L(-1). The electrode has a response time of about 40s, and it can be used for at least 1 month without observing any considerable deviation from Nernstian response. The proposed electrode revealed an excellent selectivity toward platinum(II) ion over a wide variety of alkali, alkaline earth, transition, and heavy metal ions, and it could be used in the pH range of 3.2-5.1. The practical utility of the electrode has been demonstrated by its use in determination of platinum ion in, alloy, tap, mineral and river water samples.
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http://dx.doi.org/10.1016/j.talanta.2008.12.070DOI Listing
May 2009