Publications by authors named "Akhtar Hayat"

70 Publications

Tetraphenylethene probe based fluorescent silica nanoparticles for the selective detection of nitroaromatic explosives.

Anal Methods 2021 02 27;13(6):825-831. Epub 2021 Jan 27.

State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, PR China.

A simple and sensitive fluorometric method is developed utilizing aggregation-induced emission probe based silica nanoparticles for the detection of nitroaromatic explosives. A positively charged tetraphenylethene based probe (TPE-C2-2+) is doped into silica nanoparticles exploiting electrostatic interactions to produce TPE-SiO nanoparticles with a uniform particle size. The TPE-SiO nanoparticles exhibit strong fluorescence emission due to the aggregation-induced emission (AIE) effect of the doped TPE probe. The fluorescence emission of TPE-SiO offers quantitative and sensitive response to picric acid (PA), 2,4-dinitrotoluene (DNT) and 2,4,6-trinitrotoluene (TNT) which are used as model examples of nitroaromatic compounds. The fluorescence spectroscopy results show that the fluorescence emission of TPE-SiO was greatly quenched in the presence of the electron-poor nitroaromatic compounds due to the inner filter effect (IFE) and possibly the contact quenching mechanism. TPE-SiO nanoparticles show better sensitivity towards PA and could detect PA down to 0.01 μM with a linear detection range of 0.1-50 μM. The increased chemical stability, efficient high sensitivity and simple synthesis of the TPE-SiO nanoparticles demonstrate that they can be used as an excellent fluorescent probe for a wide range of electron-poor compounds, i.e. nitroaromatic compounds. Interference studies show that common interfering species with nitroexplosives such as acids, bases, volatile organic compounds, and salt solutions have a negligible effect during the sensing process.
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http://dx.doi.org/10.1039/d0ay01945cDOI Listing
February 2021

An insect acetylcholinesterase biosensor utilizing WO/g-CN nanocomposite modified pencil graphite electrode for phosmet detection in stored grains.

Food Chem 2021 Jun 7;346:128894. Epub 2021 Jan 7.

Interdisciplinary Research Center in Biomedical Materials (IRCBM), COMSATS University, Islamabad, Lahore Campus, Lahore 54000, Pakistan. Electronic address:

This study was undertaken to assess the potential of Tribolium castaneum (Red flour beetle) acetylcholinesterase (Tc-AChE) based electrochemical biosensor integrating WO/g-CN nanocomposite modified Pencil graphite electrode to detect an organophosphate insecticide, Phosmet. The WO/g-CN nanocomposite provides a non-toxic, biocompatible surface for binding the enzyme on the electrode surface, attributed to its large surface area, high conductivity, and low ohmic resistance. The proposed biosensor shows a very good analytical performance with LOD 3.6 nM for Phosmet and effectively determined Phosmet in wheat with a 99% recovery rate. Furthermore, molecular docking deciphers the binding interactions of Phosmet with Tc-AChE using a modified AutoDock LGA algorithm and an AMBER03 force field in YASARA. The kinetic parameters strongly suggest the high potency of inhibitor with the enzyme. This study presents an adaptable, rapid, and straightforward approach that opens ways towards real progress in developing commercial biosensors for pesticide detection.
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http://dx.doi.org/10.1016/j.foodchem.2020.128894DOI Listing
June 2021

MIP-Based Impedimetric Sensor for Detecting Dengue Fever Biomarker.

Appl Biochem Biotechnol 2020 Aug 26;191(4):1384-1394. Epub 2020 Feb 26.

Interdisciplinary Research Centre in Biomedical Materials (IRCBM), COMSATS University Islamabad, Lahore Campus, Lahore, 54600, Pakistan.

In this study, molecular imprinted polymer (MIP)-based impedimetric sensor has been developed to detect dengue infection at an early stage. Screen-printed carbon electrode (SPCE) was modified with electrospun nanofibers of polysulfone (PS) and then, coated with dopamine while using NS1 (non-structural protein 1-a specific and sensitive biomarker for dengue virus infection) as template during polymerization. The self-polymerization of dopamine at room temperature helps to retain exact structure of template (NS1) which results in generating geometrically fit imprinted sites for specific detection of target analyte. The electrochemical properties of MIP-modified SPCEs were studied by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) at every step of modification. Under optimal conditions, impedimetric measurements showed linear response in the range from 1 to 200 ng/mL. The developed sensor can selectively detect NS1 concentrations as low as 0.3 ng/mL. Moreover, impedimetric sensor system was also employed for NS1 determination in real human serum samples and satisfying recoveries varying from 95 to 97.14% were obtained with standard deviations of less than 5%.
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http://dx.doi.org/10.1007/s12010-020-03285-yDOI Listing
August 2020

Immobilization of Enzymes on Magnetic Beads Through Affinity Interactions.

Methods Mol Biol 2020 ;2100:189-198

BAE, Universite de Perpignan Via Domitia, Ceret, France.

The development of enzyme immobilization techniques that will not affect catalytic activity and conformation is an important research task. Affinity tags that are present or added at a specific position far from the active site in the structure of the native enzyme could be used to create strong affinity bonds between the protein structure and a surface functionalized with the complementary affinity ligand. These immobilization techniques are based on affinity interactions between biotin and (strept)avidin molecules, lectins and sugars, or metal chelate and histidine tag.Recent developments involve immobilization of tagged enzymes onto magnetic nanoparticles. These supports can improve the performance of immobilized biomolecules in analytical assay because magnetic beads provide a relative large numbers of binding sites for biochemical reactions resulting in faster assay kinetics.This chapter describes immobilization procedures of tagged enzymes onto various magnetic beads.
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http://dx.doi.org/10.1007/978-1-0716-0215-7_12DOI Listing
January 2021

Switchable fluorescence sensor toward PAT via CA-MWCNTs quenched aptamer-tagged carboxyfluorescein.

Food Chem 2020 May 17;312:126048. Epub 2019 Dec 17.

Interdisciplinary Research Centre in Biomedical Materials (IRCBM), COMSATS University Islamabad, Lahore Campus, 54000, Pakistan. Electronic address:

A quenching based apta-sensing platform was developed for the detection of Patulin. Three different aptamer sequences were studied to screen the aptamer with the maximum affinity towards Patulin. Carboxyfluorescein (CFL) was used as a fluorescent dye while -COOH functionalized multiwall carbon nanotubes (MWCNTs) were applied as novel nanoquenchers. Aptamer tagged at the 3' end with 40 nucleotide bases exhibited the maximum affinity towards Patulin and caused substantial fluorescence recovery. Interestingly, the limit of detection (LOD) and limit of quantification (LOQ) were calculated as 0.13 μg Land 0.41 μg L respectively. Commonly occurring mycotoxins in food were also tested to confirm the selectivity of apta-assay. The developed apta-assay was applied to a spiked apple juice sample and toxin recoveries were observed ranging from 96% to 98% (n = 3). These results demonstrated the potential of the developed apta-assay for the selective detection and quantification of Patulin in food samples.
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http://dx.doi.org/10.1016/j.foodchem.2019.126048DOI Listing
May 2020

Nitrogen-doped graphene oxide as a catalyst for the oxidation of Rhodamine B by hydrogen peroxide: application to a sensitive fluorometric assay for hydrogen peroxide.

Mikrochim Acta 2019 12 16;187(1):47. Epub 2019 Dec 16.

Interdisciplinary Research Centre in Biomedical Materials (IRCBM), COMSATS University Islamabad, Lahore Campus, Lahore, Punjab, 54000, Pakistan.

The authors report that nitrogen-doped graphene oxide (NGO) catalyzes the oxidative decomposition of the fluorophore Rhodamine B (RhB) by hydrogen peroxide. The catalytic decomposition of hydrogen peroxide yields free hydroxyl radicals that destroy RhB so that the intensity of the yellow fluorescence is reduced. Nitrogen doping enhances the electronic and optical properties and surface chemical reactivities of GO such as widening of bandgap, increase in conductivity, enhanced quenching and adsorbing capabilities etc. The catalytic properties of NGO are attributed to its large specific surface and high electron affinity of nitrogen atoms. The chemical and structural properties of GO and NGO were characterized by XRD, FTIR, SEM, UV-visible and Raman spectroscopies. The method was optimized by varying the concentration of RhB, nitrogen dopant and hydrogen peroxide. The fluorescent probe, best operated at excitation/emission wavelengths of 554/577 nm, allows hydrogen peroxide to be determined in concentrations as low as 94 pM with a linear range spanning from 1 nM to 1 μM. Graphical abstract Schematic illustration of a fluorescence quenching method for the determination of HO. Upon addition of HO, nitrogen-doped graphene oxide (NGO) catalyzes the oxidation of Rhodamine B dye due to hydroxyl radical generation, which leads to a sensitive quenchometric methd for H O.
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http://dx.doi.org/10.1007/s00604-019-3994-4DOI Listing
December 2019

Polymer scaffold layers of screen-printed electrodes for homogeneous deposition of silver nanoparticles: application to the amperometric detection of hydrogen peroxide.

Mikrochim Acta 2019 11 19;186(12):810. Epub 2019 Nov 19.

BAE Laboratory, Université de Perpignan Via Domitia, 52 Avenue Paul Alduy, 66860, Perpignan, France.

A method is described for electrochemical oxidation of polymers on the surface of screen-printed electrodes (SPCE). These act as scaffold layers for homogeneous deposition of silver nanoparticles (AgNPs). Hexamethylenediamine (HMDA) and poly(ethylene glycol) were immobilized on the SPCE surface via electrochemical oxidation. AgNPs were then electrodeposited on the scaffolds on the SPCE. This type of different carbon chain containing materials like PEG and HMDA act as big tunnels for electron mobility and are useful for the homogenous deposition of AgNPs on the SPCE surface without agglomeration. The resulting sensor was applied to the determination of hydrogen peroxide (HO) as a model analyte. It is found to display favorable catalytic and conductive properties towards the reduction of HO. Cyclic voltammetry and amperometry revealed that the modified electrode performs better than other modified SPCEs. Best operated at a potential of around -0.61 V (vs Ag|AgCl), the amperometric response is linear in the 10-180 μM HO concentration range and the detection limit is 1.5 μM. The sensor is stable and reproducible. The resultant sensor was appplied to toothpaste analysis, and good recovery values were gained. Graphical abstractSchematic representation of electropolymerization of poly(ethylene glycol) and hexamethylenediamine scaffold layers on screen-printed electrodes for homogeneous electrodeposition of silver nanoparticles. This electrode was applied for the amperometric determination of hydrogen peroxide.
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http://dx.doi.org/10.1007/s00604-019-3963-yDOI Listing
November 2019

Construction of sponge-like graphitic carbon nitride and silver oxide nanocomposite probe for highly sensitive and selective turn-off fluorometric detection of hydrogen peroxide.

J Colloid Interface Sci 2020 Jan 28;558:230-241. Epub 2019 Sep 28.

Interdisciplinary Research Centre in Biomedical Materials (IRCBM), COMSATS University Islamabad, Lahore Campus, 1.5 Km Defence Road, Off Raiwind Road, Lahore, Punjab 54000, Pakistan. Electronic address:

In the present work, spongy graphitic carbon nitride (GCN) and silver oxide nanocomposites were prepared through a facile hydrothermal method at 160 °C for 4 h using GCN, silver nitrate, and dipotassium hydrogen phosphate as the starting materials. The prepared samples were characterized by scanning electron microscopy, energy dispersive X-ray spectrometry, Brunauer-Emmett-Teller method, X-ray diffraction, X-ray photoelectron spectroscopy (XPS), UV-Visible diffuse reflectance spectroscopy, Fourier transform infrared spectroscopy, Raman, and photoluminescence techniques. SEM images showed AgO loaded GCN nanocomposite has a sponge-like structure due to the interconnecting of the enormous layer on the planar structure of GCN. XRD of samples showed the diffraction planes due to the hexagonal structure of carbon nitride with a decrease in intensity of peaks with increasing silver oxide (AgO) in the nanocomposite. Further, the addition of silver oxide improved the electrical properties of the nanocomposite by reducing the recombination of electron and hole pairs as shown by photoluminescence spectra. XPS spectra have confirmed the oxidation state of Ag as well as the coexistence of AgO and GCN in the nanocomposite. BET results indicated the increase in surface area for AgO/GCN-4.2% nanocomposite as compared to GCN. FTIR study indicated that the graphitic structure in GCN remained intact with the loading of AgO. A fluorescent quenching based HO sensor was constructed by simultaneous oxidation of Rhodamine B in the presence of hydrogen peroxide and nanocomposite as the catalyst. In phosphate buffer saline at room temperature, Rhodamine B displayed a strong fluorescence emission peak around 577 nm under an excitation wavelength of 554 nm. This fluorescence signal of Rhodamine B was quenched in the presence of HO and nanocomposite. The catalytic fluorescence quenching was increased with the increase in HO concentration in the reaction system. The detection conditions of the prepared sensor were optimized as a reaction temperature of 25 °C, Rhodamine B concentration as 66 ng mL and nanocomposite concentration as 56 µg mL. The catalytic fluorescence quenching response of the biosensor exhibited a linear range and limit of detection for HO as 30-300 nM and 22 nM respectively.
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http://dx.doi.org/10.1016/j.jcis.2019.09.109DOI Listing
January 2020

A nanocomposite prepared from magnetite nanoparticles, polyaniline and carboxy-modified graphene oxide for non-enzymatic sensing of glucose.

Mikrochim Acta 2019 04 2;186(5):267. Epub 2019 Apr 2.

Interdisciplinary Research Centre in Biomedical Materials (IRCBM), COMSATS University Islamabad Lahore Campus, Lahore, 55150, Pakistan.

The authors report on the synthesis of carboxy functionalized graphene oxide (fGO) decorated with magnetite (FeO) nanoparticles. The resulting nanomaterial was used to prepare a composite with polyaniline (PANI) which was characterized by UV-vis, Fourier transform-infrared and Raman spectroscopies. Its surface morphologies were characterized by atomic force and scanning electron microscopies. A screen-printed carbon electrode was then modified with the nanocomposite to obtain an enzyme-free glucose sensor. The large surface of fGO and FeO along with the enhanced charge transfer capability of PANI warrant a pronounced electrochemical response (typically measured at 0.18 V versus Ag/AgCl) which is suppressed in the presence of glucose. This reduction of current by glucose was used to design a sensitive method for quantification of glucose. The response of the modified SPCE is linear in the 0.05 μM - 5 mM glucose concentration range, and the lower detection limit is 0.01 μM. Graphical abstract Schematic illustration of in-situ anchoring of Iron oxide on functionalized graphene oxide and synthesis of its polymeric nanocomposite for non-enzymatic detection of Glucose. The nanocomposite modified screen printed interface enabled monitoring of glucose at lower potential with higher precision. GO (graphene oxide), fGO (functionalized graphene oxide), PANI (polyaniline).
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http://dx.doi.org/10.1007/s00604-019-3364-2DOI Listing
April 2019

A Review of the Construction of Nano-Hybrids for Electrochemical Biosensing of Glucose.

Biosensors (Basel) 2019 Mar 25;9(1). Epub 2019 Mar 25.

BAE: Biocapteurs-Analyses-Environnement, Universite de Perpignan ViaDomitia, 52 Avenue Paul Alduy, 66860 Perpignan CEDEX, France.

Continuous progress in the domain of nano and material science has led to modulation of the properties of nanomaterials in a controlled and desired fashion. In this sense, nanomaterials, including carbon-based materials, metals and metal oxides, and composite/hybrid materials have attracted extensive interest with regard to the construction of electrochemical biosensors. The modification of a working electrode with a combination of two or three nanomaterials in the form of nano-composite/nano-hybrids has revealed good results with very good reproducibility, stability, and improved sensitivity. This review paper is focused on discussing the possible constructs of nano-hybrids and their subsequent use in the construction of electrochemical glucose biosensors.
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http://dx.doi.org/10.3390/bios9010046DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6468850PMC
March 2019

Development of an Impedimetric Aptasensor for Label Free Detection of Patulin in Apple Juice.

Molecules 2019 Mar 13;24(6). Epub 2019 Mar 13.

BAE: Biocapteurs-Analyses-Environnement, Universite de Perpignan Via Domitia, 52 Avenue Paul Alduy, 66860 Perpignan CEDEX, France.

In the present work, an aptasensing platform was developed for the detection of a carcinogenic mycotoxin termed patulin (PAT) using a label-free approach. The detection was mainly based on a specific interaction of an aptamer immobilized on carbon-based electrode. A long linear spacer of carboxy-amine polyethylene glycol chain (PEG) was chemically grafted on screen-printed carbon electrodes (SPCEs) via diazonium salt in the aptasensor design. The NH₂-modified aptamer was then attached covalently to carboxylic acid groups of previously immobilized bifunctional PEG to build a diblock macromolecule. The immobilized diblocked molecules resulted in the formation of long tunnels on a carbon interface, while the aptamer was assumed as the gate of these tunnels. Upon target analyte binding, the gates were assumed to be closed due to conformational changes in the structure of the aptamer, increasing the resistance to the charge transfer. This increase in resistance was measured by electrochemical impedance spectroscopy, the main analytical technique for the quantitative detection of PAT. Encouragingly, a good linear range between 1 and 25 ng was obtained. The limit of detection and limit of quantification was 2.8 ng L and 4.0 ng L, respectively. Selectivity of the aptasensor was confirmed with mycotoxins commonly occurring in food. The developed apta-assay was also applied to a real sample, i.e., fresh apple juice spiked with PAT, and toxin recovery up to 99% was observed. The results obtained validated the suitability and selectivity of the developed apta-assay for the identification and quantification of PAT in real food samples.
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http://dx.doi.org/10.3390/molecules24061017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6471267PMC
March 2019

Development of a disposable electrochemical sensor for detection of cholesterol using differential pulse voltammetry.

J Pharm Biomed Anal 2018 Sep 17;159:398-405. Epub 2018 Jul 17.

Interdisciplinary Research Centre in Biomedical Materials (IRCBM), COMSATS Institute of Information Technology, Lahore, Pakistan. Electronic address:

In this study, a sensitive and selective electrochemical sensor was fabricated by using a screen printed carbon electrode (SPCE), multi-walled carbon nanotubes (MWCNTs) and β-cyclodextrin (β-CD) for detecting cholesterol. MWCNTs were functionalized with benzoic acid moiety by employing diazonium salt chemistry, and, subsequently, a thin film of functionalized CNTs were coated on the surface of SPCE. Afterwards, β-CD was immobilized on functionalized MWCNTs modified SPCE which acts as a host to recognize guest (cholesterol) molecule specifically. Under the optimal experimental conditions and using differential pulse voltammetry (DPV) as transduction technique the sensor was able to detect cholesterol level ranges from 1 nM to 3 μM, with a detection limit of 0.5 nM. Specificity of the developed sensor towards target analyte (cholesterol) was confirmed in the presence of common interfering species including glucose, uric acid and ascorbic acid. The applicability of proposed sensor was also demonstrated for cholesterol determination in human serum samples with good recovery results (94-96%) and maximum RSD (relative standard deviation) of 4.5%.
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http://dx.doi.org/10.1016/j.jpba.2018.07.005DOI Listing
September 2018

Design of a novel filter paper based construct for rapid analysis of acetone.

PLoS One 2018 6;13(7):e0199978. Epub 2018 Jul 6.

Interdisciplinary Research centre in Biomedical Materials (IRCBM), COMSATS Institute of Information technology, Lahore, Pakistan.

The present work was focused to design a cheap, rapid, portable and easy to use filter paper based assay for the qualitative and quantitate analysis of acetone. Sodium alginate gel was loaded with the acetone specific optical signal probe, and subsequently coated onto filter paper surface to design portable colorimetric assays for acetone monitoring. The color of the paper sensor strip was observed to change from dark yellow to light yellowish in the presence of varying concentrations of acetone. Three different color analyzing models including RGB, HSV, and LAB were employed to probe the output optical signal, and their performance was compared in terms of better interpretation of the generated signal. The LAB model was found to provide better analytical figures of merit with a linear response for the acetone concentration ranging from 2.5 to 1500 ppm, and a limit of detection of 0.5 ppm. Furthermore, the specificity of the designed filter paper based sensor was demonstrated against different common interfering compounds. The results demonstrated the potential of our proposed filter paper based sensor as a novel tool for the analysis of acetone.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0199978PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6034825PMC
January 2019

Development of a portable and disposable NS1 based electrochemical immunosensor for early diagnosis of dengue virus.

Anal Chim Acta 2018 Oct 18;1026:1-7. Epub 2018 Apr 18.

BAE: Biocapteurs-Analyses-Environment, Universite de Perpignan Via Domitia, 52 Avenue Paul Alduy, Perpignan Cedex, 66860, France. Electronic address:

The present study represents fabrication of nonstructural antibody (NS1) based immunosensor coupled with bovine serum albumin (BSA) modified screen printed carbon electrodes (SPCE) as transducing substrate for the early diagnosis of dengue virus. The anti-NS1 monoclonal antibody was immobilized on electro grafted BSA surface of working electrode. The electrons transfer resistance before and after NS1 attachment was monitored as a function of its concentration to perform the qualitative and quantitative analysis. The as prepared impedimetric immunosensor successfully detected the dengue virus protein with enhanced limit of detection (0.3 ng/mL) and linear range (1-200 ng/mL). The selectivity of the designed device was further elaborated with several interfering analytes and was finally demonstrated with human serum samples. The extravagant selectivity, sensitivity and easier fabrication protocol corroborate the potential applications of such immunosensor for practical diagnosis of dengue virus.
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http://dx.doi.org/10.1016/j.aca.2018.04.032DOI Listing
October 2018

Ionic liquid coated iron nanoparticles are promising peroxidase mimics for optical determination of HO.

Mikrochim Acta 2018 05 16;185(6):302. Epub 2018 May 16.

Interdisciplinary Research Centre in Biomedical Materials (IRCBM) COMSATS Institute of Information Technology, Lahore, 54000, Pakistan.

Ionic liquid coated nanoparticles (IL-NPs) consisting of zero-valent iron are shown to display intrinsic peroxidase-like activity with enhanced potential to catalyze the oxidation of the chromogenic substrate 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide. This results in the formation of a blue green colored product that can be detected with bare eyes and quantified by photometry at 652 nm. The IL-NPs were further doped with bismuth to enhance its catalytic properties. The Bi-doped IL-NPs were characterized by FTIR, X-ray diffraction and scanning electron microscopy. A colorimetric assay was worked out for hydrogen peroxide that is simple, sensitive and selective. Response is linear in the 30-300 μM HO concentration range, and the detection limit is 0.15 μM. Graphical abstract Schematic of ionic liquid coated iron nanoparticles that display intrinsic peroxidase-like activity. They are capable of oxidizing the chromogenic substrate 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide. This catalytic oxidation generated blue-green color can be measured by colorimetry. Response is linear in the range of 30-300 μM HO concentration, and the detection limit is 0.15 μM.
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http://dx.doi.org/10.1007/s00604-018-2841-3DOI Listing
May 2018

Designed Strategies for Fluorescence-Based Biosensors for the Detection of Mycotoxins.

Toxins (Basel) 2018 05 11;10(5). Epub 2018 May 11.

BAE: Biocapteurs-Analyses-Environnement, Universite de Perpignan Via Domitia, 52 Avenue Paul Alduy, 66860 Perpignan CEDEX, France.

Small molecule toxins such as mycotoxins with low molecular weight are the most widely studied biological toxins. These biological toxins are responsible for food poisoning and have the potential to be used as biological warfare agents at the toxic dose. Due to the poisonous nature of mycotoxins, effective analysis techniques for quantifying their toxicity are indispensable. In this context, biosensors have been emerged as a powerful tool to monitors toxins at extremely low level. Recently, biosensors based on fluorescence detection have attained special interest with the incorporation of nanomaterials. This review paper will focus on the development of fluorescence-based biosensors for mycotoxin detection, with particular emphasis on their design as well as properties such as sensitivity and specificity. A number of these fluorescent biosensors have shown promising results in food samples for the detection of mycotoxins, suggesting their future potential for food applications.
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http://dx.doi.org/10.3390/toxins10050197DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5983253PMC
May 2018

Photoinduced discharge of electrons stored in a TiO2-MWCNT composite to an analyte: application to the fluorometric determination of hydrogen peroxide, glucose and aflatoxin B1.

Mikrochim Acta 2017 12 6;185(1):26. Epub 2017 Dec 6.

Interdisciplinary Research Centre in Biomedical Materials (IRCBM), COMSATS Institute of Information Technology (CIIT), Lahore, 54000, Pakistan.

The authors describe an analytical detection scheme based on the use of multiwalled carbon nanotubes (MWCNTs) that accept and store electrons upon contact with photo-irradiated TiO nanoparticles (TiO-NPs). The Fermi level equilibration with photo-irradiated TiO-NPs has a storage value of 0.35 mM of electrons per 120 mg·L of MWCNTs. The stored electrons can be discharged on demand upon addition of electron acceptors to the TiO-NP/MWCNT composite. These findings are applied to detect the quencher hydrogen peroxide. HO also is produced on enzymatic action of glucose oxidase on glucose, and this enables glucose also to be quantified by using the TiO-NP/MWCNT fluorescent nanoprobe. The wide scope of the method also is demonstrated by an assay for aflatoxin B1 that is making use of an FAM-labeled aptamer where the FAM fluorophore on the aptamer quenches the emission of the nanoprobe. The following analytical linear ranges and limits of detection are found: HO: 0.1-100 μM and 15 nM; glucose: 5-200 μM and 0.5 μM; aflatoxin: 0.1-40 ng·mL and 0.02 ng·mL. The method was applied to the determination of glucose in human serum. Graphical abstract The assays demonstrated in (b) and (c) are based on the fluorescence quenching ability of MWCNTs-TiO. In the presence of the target (analyte), the fluorescence is restored and the target concentration is determined from the percentage of fluorescence recovery.
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http://dx.doi.org/10.1007/s00604-017-2583-7DOI Listing
December 2017

DNA assay based on Nanoceria as Fluorescence Quenchers (NanoCeracQ DNA assay).

Sci Rep 2018 02 5;8(1):2426. Epub 2018 Feb 5.

Department of Chemistry and Biomolecular Science, Clarkson University, Potsdam, New York, 13699, United States.

Functional nanomaterials with fluorescent or quenching abilities are important for the development of molecular probes for detection and studies of nucleic acids. Here, we describe a new class of molecular nanoprobes, the NanoCeracQ that uses nanoceria particles as a nanoquencher of fluorescent oligonucleotides for rapid and sensitive detection of DNA sequences and hybridization events. We show that nanoceria forms stable and reversible bionanoconjugates with oligonucleotides and can specifically recognize and detect DNA sequences in a single step. In absence of the target DNA, the nanoprobe produced minimal background fluorescence due to the high quenching efficiency of nanoceria. Competitive binding of the target induced a concentration dependent increase in the fluorescence signal due to hybridization and release of the fluorescent tag from the nanoparticle surface. The nanoprobe enabled sensitive detection of the complementary strand with a detection limit of 0.12 nM, using a single step procedure. The results show that biofunctionalized nanoceria can be used as a universal nanoquencher and nanosensing platform for fluorescent DNA detection and studies of nucleic acid interactions. This approach can find broad applications in molecular diagnostics, sensor development, gene expression profiling, imaging and forensic analysis.
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http://dx.doi.org/10.1038/s41598-018-20659-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5799284PMC
February 2018

Carboxylic group riched graphene oxide based disposable electrochemical immunosensor for cancer biomarker detection.

Anal Biochem 2018 03 12;545:13-19. Epub 2018 Jan 12.

Interdisciplinary Research Centre in Biomedical Materials (IRCBM), COMSATS Institute of Information Technology (CIIT), Lahore, 54000, Pakistan. Electronic address:

In this work, we have developed for the first time a carboxylic group riched graphene oxide based disposable electrochemical immunosensor for cancer biomarker detection using methylene blue (MB). The developed immunosensor is highly sensitive for detection of biomarker Mucin1 (MUC1) in human serum samples. Development of this disposable electrochemical immunosensor was premeditated by applying specific monoclonal antibodies against MUC1. In this method, we explored highly conductive surface of carboxylic group (-COOH-) rich graphene oxide (GO) on screen-printed carbon electrodes (SPCE). This modified GO-COOH-SPCE was employed for the detection of MUC1 protein based on the reaction with methylene blue (MB) redox probe using differential pulse voltammetry (DPV) technique. Developed immunosensor exhibited good detection range for MUC1 with excellent linearity (0.1 U/mL- 2 U/mL), with a limit of detection of 0.04 U/mL. Upon potential application of developed biosensor, good recoveries were recorded in the range of 96-96.67% with % R.S.D 4.2. Analytical performance of the developed immunosensor assures the applicability in clinical diagnostic applications.
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http://dx.doi.org/10.1016/j.ab.2018.01.007DOI Listing
March 2018

Nano-Aptasensing in Mycotoxin Analysis: Recent Updates and Progress.

Toxins (Basel) 2017 10 28;9(11). Epub 2017 Oct 28.

BAE: Biocapteurs-Analyses-Environnement, Universite de Perpignan Via Domitia, 52 Avenue Paul Alduy, 66860 Perpignan CEDEX, France.

Recent years have witnessed an overwhelming integration of nanomaterials in the fabrication of biosensors. Nanomaterials have been incorporated with the objective to achieve better analytical figures of merit in terms of limit of detection, linear range, assays stability, low production cost, etc. Nanomaterials can act as immobilization support, signal amplifier, mediator and artificial enzyme label in the construction of aptasensors. We aim in this work to review the recent progress in mycotoxin analysis. This review emphasizes on the function of the different nanomaterials in aptasensors architecture. We subsequently relate their features to the analytical performance of the given aptasensor towards mycotoxins monitoring. In the same context, a critically analysis and level of success for each nano-aptasensing design will be discussed. Finally, current challenges in nano-aptasensing design for mycotoxin analysis will be highlighted.
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http://dx.doi.org/10.3390/toxins9110349DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5705964PMC
October 2017

An Overview on Recent Progress in Electrochemical Biosensors for Antimicrobial Drug Residues in Animal-Derived Food.

Sensors (Basel) 2017 Aug 24;17(9). Epub 2017 Aug 24.

BAE: Biocapteurs-Analyses-Environnement, Universite de Perpignan Via Domitia, 52 Avenue Paul Alduy, Perpignan CEDEX 66860, France.

Anti-microbial drugs are widely employed for the treatment and cure of diseases in animals, promotion of animal growth, and feed efficiency. However, the scientific literature has indicated the possible presence of antimicrobial drug residues in animal-derived food, making it one of the key public concerns for food safety. Therefore, it is highly desirable to design fast and accurate methodologies to monitor antimicrobial drug residues in animal-derived food. Legislation is in place in many countries to ensure antimicrobial drug residue quantities are less than the maximum residue limits (MRL) defined on the basis of food safety. In this context, the recent years have witnessed a special interest in the field of electrochemical biosensors for food safety, based on their unique analytical features. This review article is focused on the recent progress in the domain of electrochemical biosensors to monitor antimicrobial drug residues in animal-derived food.
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http://dx.doi.org/10.3390/s17091947DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5621119PMC
August 2017

Biomimetic nitrogen doped titania nanoparticles as a colorimetric platform for hydrogen peroxide detection.

J Colloid Interface Sci 2017 Nov 6;505:1147-1157. Epub 2017 Jul 6.

Interdisciplinary Research Centre in Biomedical Materials (IRCBM), COMSATS Institute of Information Technology, Lahore 54000, Pakistan. Electronic address:

Nanoparticles proved a viable alternative to the already used sensing and diagnostics methods due to their low cost, good stability, easy availability and easy synthesis. In the present approach, nitrogen doped titania nanoparticles are prepared through freeze drying method, and subsequently stabilized through ionic liquid. These nanoparticles were characterized through various techniques such as X-ray diffraction (XRD), Fourier transformation infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), BET pore size and surface area analyzer, X-ray photoelectron spectroscopy (XPS) and UV-Visible diffuse reflectance spectroscopy (UV-Vis. DRS). The synthesized nitrogen doped titania nanoparticles were proved to be a novel peroxidase mimetic with great potential to catalyze oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (HO) to form a blue color product. As a proof of concept, this new enzyme mimic was used as a robust nanoprobe for the detection of hydrogen peroxide with improved analytical characteristics. A linear response for hydrogen peroxide detection was obtained in the range of 10-300μmol/L, with a detection limit of 2.5μmol/L. Taking into account the valuable intrinsic peroxidase activity, the present work may find widespread applications in the field of sensors and biosensors for diverse applications.
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http://dx.doi.org/10.1016/j.jcis.2017.07.014DOI Listing
November 2017

A novel colorimetric competitive aptamer assay for lysozyme detection based on superparamagnetic nanobeads.

Talanta 2017 Apr 30;165:436-441. Epub 2016 Dec 30.

Université de Perpignan via Domitia, Laboratoire BAE, Building S 52 Av. Paul Alduy, 66860 Perpignan Cedex, France. Electronic address:

Lysozyme (Lys) commonly presents in wines and are known to cause toxicological impact on human health. The need of highly sensitive and reliable detection methods are evident in such matrix. In this work, we developed a competitive aptamer based assay for detection of Lys by employing carboxylated magnetic beads as a support to immobilize the target molecule Lys. The used aptamer sequence was biotinylated which further binds with Streptavidin-Alkaline phosphatase (Stp-ALP) in the micro wells. Colorimetric tests were performed in order to optimize different experimental parameters. The Lys assay showed a good linearity in the range of 5-140nM with a limit of detection (LOD) 10nM. The mid-point value (IC) 110nM and the analysis time (60min) validated the developed aptasensor as a promising tool for routine use. The assay displayed good recoveries of Lys in the range 99.00-99.27% and was demonstrated for the detection of Lys in wine samples.
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http://dx.doi.org/10.1016/j.talanta.2016.12.083DOI Listing
April 2017

Label-Free Aptasensors for the Detection of Mycotoxins.

Sensors (Basel) 2016 Dec 18;16(12). Epub 2016 Dec 18.

BAE Laboratory, Université de Perpignan Via Domitia, 52 Avenue Paul Alduy, Perpignan 66860, France.

Various methodologies have been reported in the literature for the qualitative and quantitative monitoring of mycotoxins in food and feed samples. Based on their enhanced specificity, selectivity and versatility, bio-affinity assays have inspired many researchers to develop sensors by exploring bio-recognition phenomena. However, a significant problem in the fabrication of these devices is that most of the biomolecules do not generate an easily measurable signal upon binding to the target analytes, and signal-generating labels are required to perform the measurements. In this context, aptamers have been emerged as a potential and attractive bio-recognition element to design label-free aptasensors for various target analytes. Contrary to other bioreceptor-based approaches, the aptamer-based assays rely on antigen binding-induced conformational changes or oligomerization states rather than binding-assisted changes in adsorbed mass or charge. This review will focus on current designs in label-free conformational switchable design strategies, with a particular focus on applications in the detection of mycotoxins.
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http://dx.doi.org/10.3390/s16122178DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5191157PMC
December 2016

Nano-Engineered Biomimetic Optical Sensors for Glucose Monitoring in Diabetes.

Sensors (Basel) 2016 Nov 17;16(11). Epub 2016 Nov 17.

Interdisciplinary Research Centre in Biomedical Materials (IRCBM), COMSATS Institute of Information Technology, 54000 Lahore, Pakistan.

Diabetes is a rapidly growing disease that can be monitored at an individual level by controlling the blood glucose level, hence minimizing the negative impact of the disease. Significant research efforts have been focused on the design of novel and improved technologies to overcome the limitations of existing glucose analysis methods. In this context, nanotechnology has enabled the diagnosis at the single cell and molecular level with the possibility of incorporation in advanced molecular diagnostic biochips. Recent years have witnessed the exploration and synthesis of various types of nanomaterials with enzyme-like properties, with their subsequent integration into the design of biomimetic optical sensors for glucose monitoring. This review paper will provide insights on the type, nature and synthesis of different biomimetic nanomaterials. Moreover, recent developments in the integration of these nanomaterials for optical glucose biosensing will be highlighted, with a final discussion on the challenges that must be addressed for successful implementation of these nano-devices in the clinical applications is presented.
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http://dx.doi.org/10.3390/s16111931DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5134590PMC
November 2016

Electrochemical Affinity Biosensors Based on Disposable Screen-Printed Electrodes for Detection of Food Allergens.

Sensors (Basel) 2016 Nov 5;16(11). Epub 2016 Nov 5.

BAE Laboratory, Université de Perpignan Via Domitia, 52 Avenue Paul Alduy, 66860 Perpignan, France.

Food allergens are proteins from nuts and tree nuts, fish, shellfish, wheat, soy, eggs or milk which trigger severe adverse reactions in the human body, involving IgE-type antibodies. Sensitive detection of allergens in a large variety of food matrices has become increasingly important considering the emergence of functional foods and new food manufacturing technologies. For example, proteins such as casein from milk or lysozyme and ovalbumin from eggs are sometimes used as fining agents in the wine industry. Nonetheless, allergen detection in processed foods is a challenging endeavor, as allergen proteins are degraded during food processing steps involving heating or fermentation. Detection of food allergens was primarily achieved via Enzyme-Linked Immuno Assay (ELISA) or by chromatographic methods. With the advent of biosensors, electrochemical affinity-based biosensors such as those incorporating antibodies and aptamers as biorecognition elements were also reported in the literature. In this review paper, we highlight the success achieved in the design of electrochemical affinity biosensors based on disposable screen-printed electrodes towards detection of protein allergens. We will discuss the analytical figures of merit for various disposable screen-printed affinity sensors in relation to methodologies employed for immobilization of bioreceptors on transducer surface.
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http://dx.doi.org/10.3390/s16111863DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5134522PMC
November 2016

One Step Assembly of Thin Films of Carbon Nanotubes on Screen Printed Interface for Electrochemical Aptasensing of Breast Cancer Biomarker.

Sensors (Basel) 2016 Oct 6;16(10). Epub 2016 Oct 6.

Interdisciplinary Research Centre in Biomedical Materials (IRCBM), COMSATS Institute of Information Technology, Lahore 54000, Pakistan.

Thin films of organic moiety functionalized carbon nanotubes (CNTs) from a very well-dispersed aqueous solution were designed on a screen printed transducer surface through a single step directed assembly methodology. Very high density of CNTs was obtained on the screen printed electrode surface, with the formation of a thin and uniform layer on transducer substrate. Functionalized CNTs were characterized by X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and Brunauer-Emmett- Teller (BET) surface area analyzer methodologies, while CNT coated screen printed transducer platform was analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The proposed methodology makes use of a minimum amount of CNTs and toxic solvents, and is successfully demonstrated to form thin films over macroscopic areas of screen printed carbon transducer surface. The CNT coated screen printed transducer surface was integrated in the fabrication of electrochemical aptasensors for breast cancer biomarker analysis. This CNT coated platform can be applied to immobilize enzymes, antibodies and DNA in the construction of biosensor for a broad spectrum of applications.
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http://dx.doi.org/10.3390/s16101651DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5087439PMC
October 2016

Biomolecular detection at ssDNA-conjugated nanoparticles by nano-impact electrochemistry.

Biosens Bioelectron 2017 Jan 31;87:501-507. Epub 2016 Aug 31.

Department of Chemistry and Biomolecular Science, Clarkson University, Potsdam, NY, USA. Electronic address:

We describe the use of ssDNA functionalized silver nanoparticle (AgNP) probes for quantitative investigation of biorecognition and real time detection of biomolecular targets using nano-impact electrochemistry. The method is based on measurements of the individual collision events between ssDNA aptamer-functionalized AgNPs and a carbon fiber miroelectrode (CFME). Specific binding events of target analyte induced collision frequency changes enabling ultrasensitive detection of the aptamer target in a single step. These changes are assigned to the surface coverage of the NP by the ssDNA aptamers and subsequent conformational changes of the aptamer probe which affect the electron transfer between the NP and the electrode surface. The method enables sensitive and selective detection of ochratoxin A (OTA), chosen here as a model target, with a limit of detection of 0.05nM and a relative standard deviation of 4.9%. The study provides a means of characterizing bioconjugation of AgNPs with aptamers and assessing biomolecular recognition events with high sensitivity and without the use of exogenous reagents or enzyme amplification steps. This methodology can be broadly applicable to other bioconjugated systems, biosensing and related bioanalytical applications.
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http://dx.doi.org/10.1016/j.bios.2016.08.108DOI Listing
January 2017

New biorecognition molecules in biosensors for the detection of toxins.

Biosens Bioelectron 2017 Jan 29;87:285-298. Epub 2016 Jun 29.

BAE (Biocapteurs-Analyses-Environnement), Universite de Perpignan Via Domitia, 52 Avenue Paul Alduy, Perpignan Cedex 66860, France.

Biological and synthetic recognition elements are at the heart of the majority of modern bioreceptor assays. Traditionally, enzymes and antibodies have been integrated in the biosensor designs as a popular choice for the detection of toxin molecules. But since 1970s, alternative biological and synthetic binders have been emerged as a promising alternative to conventional biorecognition elements in detection systems for laboratory and field-based applications. Recent research has witnessed immense interest in the use of recombinant enzymatic methodologies and nanozymes to circumvent the drawbacks associated with natural enzymes. In the area of antibody production, technologies based on the modification of in vivo synthesized materials and in vitro approaches with development of "display "systems have been introduced in the recent years. Subsequently, molecularly-imprinted polymers and Peptide nucleic acid (PNAs) were developed as an attractive receptor with applications in the area of sample preparation and detection systems. In this article, we discuss all alternatives to conventional biomolecules employed in the detection of various toxin molecules We review recent developments in modified enzymes, nanozymes, nanobodies, aptamers, peptides, protein scaffolds and DNazymes. With the advent of nanostructures and new interface materials, these recognition elements will be major players in future biosensor development.
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http://dx.doi.org/10.1016/j.bios.2016.06.083DOI Listing
January 2017

Portable and low cost fluorescence set-up for in-situ screening of Ochratoxin A.

Talanta 2016 Oct 23;159:395-400. Epub 2016 Jun 23.

Université de Perpignan Via Domitia, Laboratoire BAE, Building S 52 Av. Paul Alduy, 66860 Perpignan Cedex, France. Electronic address:

The present article describes a portable and low cost fluorescence set-up designed and characterized for in-situ screening of Ochratoxin A (OTA) in cocoa samples at field settings. The sensing module (the set up) consists of a LED with the wavelength of 370-380nm and a color complementary metal oxide semiconductor (CMOS) micro-camera inbuilt at upright position of a black box to obtain an image of the sensing molecule. It allows the user to get an image of the sensing analytes under excitation conditions and process the image in order to predict the toxicity of the samples. The image capturing and processing of the system was based on the OTA concentration in the sample and analyzed data can be presented as RGB values. For each concentration of the OTA, the R, G, B co-ordinates were obtained and plotted to quantify actual OTA presents in the sample. Moreover, the system was tested for real sample analysis using cocoa contaminated with OTA. The system could detect OTA as low as 1.25ng/ml with the maximum recovery of 87.5% in cocoa samples. The OTA was extracted in 1% NaHCO3 and cleaned up using molecular imprinted polymer column (MIP). The method demonstrated a good linear range between 1.25 and 10ng/ml. The obtained results were cross validated using chromatographic method HPLC and also compared with commercially available fluorescence instrument. The developed fluorescence setup is simple, economical, and portable with added advantages of digital image processing. The system could be deployable to cocoa fields for monitoring of OTA in quick successions. It is noteworthy to mention that this is the first report of such portable fluorescence setup where, OTA sensing was explored.
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http://dx.doi.org/10.1016/j.talanta.2016.06.039DOI Listing
October 2016