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SU-8 based microprobes with integrated planar electrodes for enhanced neural depth recording
11 June 2012,
09:04:54
Publication year:
2012
Source:Biosensors and Bioelectronics, Volume 37, Issue 1
Ane Altuna, Liset Menendez de la Prida, Elisa Bellistri, Gemma Gabriel, Anton Guimerá, Javier Berganzo, Rosa Villa, Luis J. Fernández
Here, we describe new fabrication methods aimed to integrate planar tetrode-like electrodes into a polymer SU-8 based microprobe for neuronal recording applications. New concepts on the fabrication sequences are introduced in order to eliminate the typical electrode–tissue gap associated to the passivation layer. Optimization of the photolithography technique and high step coverage of the sputtering process have been critical steps in this new fabrication process. Impedance characterization confirmed the viability of the electrodes for reliable neuronal recordings with values comparable to commercial probes. Furthermore, a homogeneous sensing behavior was obtained in all the electrodes of each probe. Finally, in vivo action potential and local field potential recordings were successfully obtained from the rat dorsal hippocampus. Peak-to-peak amplitude of action potentials ranged from noise level to up to 400–500μV. Moreover, action potentials of different amplitudes and shapes were recorded from all the four recording sites, suggesting improved capability of the tetrode to distinguish from different neuronal sources.
Source:Biosensors and Bioelectronics, Volume 37, Issue 1
Ane Altuna, Liset Menendez de la Prida, Elisa Bellistri, Gemma Gabriel, Anton Guimerá, Javier Berganzo, Rosa Villa, Luis J. Fernández
Here, we describe new fabrication methods aimed to integrate planar tetrode-like electrodes into a polymer SU-8 based microprobe for neuronal recording applications. New concepts on the fabrication sequences are introduced in order to eliminate the typical electrode–tissue gap associated to the passivation layer. Optimization of the photolithography technique and high step coverage of the sputtering process have been critical steps in this new fabrication process. Impedance characterization confirmed the viability of the electrodes for reliable neuronal recordings with values comparable to commercial probes. Furthermore, a homogeneous sensing behavior was obtained in all the electrodes of each probe. Finally, in vivo action potential and local field potential recordings were successfully obtained from the rat dorsal hippocampus. Peak-to-peak amplitude of action potentials ranged from noise level to up to 400–500μV. Moreover, action potentials of different amplitudes and shapes were recorded from all the four recording sites, suggesting improved capability of the tetrode to distinguish from different neuronal sources.
Highlights
► Electrodes at the SU-8 probe surface level have been fabricated. ► Different amplitude and shape of action potentials were distinguished. ► Peak-to-peak amplitude of action potentials ranged up to 400–500μV.Bi-enzyme synergetic catalysis to in situ generate coreactant of peroxydisulfate solution for ultrasensitive electrochemiluminescence immunoassay
11 June 2012,
09:04:54
Publication year:
2012
Source:Biosensors and Bioelectronics, Volume 37, Issue 1
Haijun Wang, Ruo Yuan, Yaqin Chai, Huan Niu, Yaling Cao, Huijing Liu
A novel electrochemiluminescence (ECL) immunosensor for ultrasensitive detection of α-1-fetoprotein (AFP) was designed based on the in situ bi-enzymatic reaction to generate coreactant of peroxydisulfate for signal amplification. In this work, AuNPs were electrodeposited on the glassy carbon electrode (GCE) surface, which promoted the electron transfer. Then, L-cysteine and another layer of AuNPs were, respectively assembled onto the modified electrode surface, which formed the multilayer films for amplifying the ECL signal of peroxydisulfate and immobilizing antibody. At last, glucose oxidase (GOD) and horseradish peroxidase (HRP) were employed to block the nonspecific binding sites. When proper amounts of glucose were added in the detection solution, GOD catalyzed the oxidation of glucose to generate H2O2, which could be further catalyzed by HRP to generate O2 for the signal amplification. The linear range for AFP detection was 0.001–100ngmL−1, with a low detection limit of 3.3×10−4 ngmL−1. The novel strategy has the advantages of simplicity, sensitivity, good selectivity and reproducibility which might hold a new promise for highly sensitive bioassays applied in clinical detection.
Source:Biosensors and Bioelectronics, Volume 37, Issue 1
Haijun Wang, Ruo Yuan, Yaqin Chai, Huan Niu, Yaling Cao, Huijing Liu
A novel electrochemiluminescence (ECL) immunosensor for ultrasensitive detection of α-1-fetoprotein (AFP) was designed based on the in situ bi-enzymatic reaction to generate coreactant of peroxydisulfate for signal amplification. In this work, AuNPs were electrodeposited on the glassy carbon electrode (GCE) surface, which promoted the electron transfer. Then, L-cysteine and another layer of AuNPs were, respectively assembled onto the modified electrode surface, which formed the multilayer films for amplifying the ECL signal of peroxydisulfate and immobilizing antibody. At last, glucose oxidase (GOD) and horseradish peroxidase (HRP) were employed to block the nonspecific binding sites. When proper amounts of glucose were added in the detection solution, GOD catalyzed the oxidation of glucose to generate H2O2, which could be further catalyzed by HRP to generate O2 for the signal amplification. The linear range for AFP detection was 0.001–100ngmL−1, with a low detection limit of 3.3×10−4 ngmL−1. The novel strategy has the advantages of simplicity, sensitivity, good selectivity and reproducibility which might hold a new promise for highly sensitive bioassays applied in clinical detection.
Highlights
► We developed a novel electrochemiluminescence (ECL) immunosensor for ultrasensitive detection of α-1-fetoprotein (AFP) based on the in situ bi-enzymatic reaction to generate coreactant of peroxydisulfate for signal amplification. ► L-Cysteine and AuNPs were used to improve the ECL signal and the absorption capacity of antibody. ► GOD and HRP were adopted to in situ generate O2 which is the coreactant of peroxydisulfate system. ► The novel strategy has the advantages of simplicity, sensitivity, good selectivity and reproducibility.Electrochemical detection of individual single nucleotide polymorphisms using monobase-modified apoferritin-encapsulated nanoparticles
11 June 2012,
09:04:54
Publication year:
2012
Source:Biosensors and Bioelectronics, Volume 37, Issue 1
Abdolkarim Abbaspour, Abolhassan Noori
An electrochemical approach for detection of individual single nucleotide polymorphisms (SNPs) based on nucleobase-conjugated apoferritin probe loaded with metal phosphate nanoparticles is reported. Coupling of the nucleotide-modified nanoparticle probe to the mutant sites of duplex DNA was induced by DNA polymerase I (Klenow fragment) to preserve Watson–Crick base-pairing rules. After sequential liquid hybridization of biotinylated DNA probes with mutant DNA and complementary DNA, the resulting duplex DNA helixes were captured to the surface of magnetic beads through a well known and specific biotin-streptavidin affinity binding. For signaling each of eight possible Single-nucleotide polymorphisms (SNPs), Pb, Cu, Cd and Zn phosphate-loaded apoferritin nanoparticle probes were linked to adenosine (A), cytidine (C), guanosine (G), and thymidine (T) mononucleotides, respectively. Monobase-conjugated apoferritin probes were coupled to the mutant sites of the formed duplex DNA in the presence of DNA polymerase. Electrochemical stripping analyses of the metals loaded in apoferritin nanoparticle probes provide a means for detection and quantification of mutant DNA. Each mutation captures different nucleotide-conjugated apoferritin probe and provide a distinct four-potential voltammogram, whose peak potentials reflect the identity of the mismatch. The method is sensitive enough to accurately determine AG mutation, as the most thermodynamically stable mismatch to detect, in the range of 50–600pM. The proposed protocol provides a simple, fast, cost-effective, accurate and sensitive method for detection of SNPs.
Source:Biosensors and Bioelectronics, Volume 37, Issue 1
Abdolkarim Abbaspour, Abolhassan Noori
An electrochemical approach for detection of individual single nucleotide polymorphisms (SNPs) based on nucleobase-conjugated apoferritin probe loaded with metal phosphate nanoparticles is reported. Coupling of the nucleotide-modified nanoparticle probe to the mutant sites of duplex DNA was induced by DNA polymerase I (Klenow fragment) to preserve Watson–Crick base-pairing rules. After sequential liquid hybridization of biotinylated DNA probes with mutant DNA and complementary DNA, the resulting duplex DNA helixes were captured to the surface of magnetic beads through a well known and specific biotin-streptavidin affinity binding. For signaling each of eight possible Single-nucleotide polymorphisms (SNPs), Pb, Cu, Cd and Zn phosphate-loaded apoferritin nanoparticle probes were linked to adenosine (A), cytidine (C), guanosine (G), and thymidine (T) mononucleotides, respectively. Monobase-conjugated apoferritin probes were coupled to the mutant sites of the formed duplex DNA in the presence of DNA polymerase. Electrochemical stripping analyses of the metals loaded in apoferritin nanoparticle probes provide a means for detection and quantification of mutant DNA. Each mutation captures different nucleotide-conjugated apoferritin probe and provide a distinct four-potential voltammogram, whose peak potentials reflect the identity of the mismatch. The method is sensitive enough to accurately determine AG mutation, as the most thermodynamically stable mismatch to detect, in the range of 50–600pM. The proposed protocol provides a simple, fast, cost-effective, accurate and sensitive method for detection of SNPs.
Highlights
► Apoferritin-encapsulated metal phosphate nanoparticles as electrochemical marker for detection of SNPs. ► Streptavidin-coated magnetic beads as a substrate for capturing biotinylated DNA probes. ► Voltammetric stripping analysis of metallic phosphate nanoparticles on a mercury coated screen printed electrode. ► Detection of all eight possible SNPs in a single voltammetric run. ► Possession of high sensitivity in detection of low concentrations of SNPs.Highly-sensitive electrochemical immunosensing method based on dual amplification systems
11 June 2012,
09:04:54
Publication year:
2012
Source:Biosensors and Bioelectronics, Volume 37, Issue 1
Tomoyuki Yasukawa, Yoshimi Yoshimoto, Takuya Goto, Fumio Mizutani
In this work, a novel immunosensing method has been developed on the basis of the sensitive determination of a product generated by an enzyme reaction with dual amplification system combining an electrochemical-redox cycling and coulometric signal transduction using a galvanic cell. Analytes were captured on microparticles to form sandwich-type immunocomplexes and then labeled with β-galactosidase (β-gal). 4-Aminophenol (PAP) produced by enzyme reaction of β-gal was introduced into the anode compartment consisting of a comb type of an interdigitated array (IDA) electrode. PAP was oxidized at the IDA electrode by the coupled reduction of silver ions at the glassy carbon (GC) electrode of the cathode, resulting in the deposition of silver metal on the GC electrode. The other comb of the IDA electrode was used to reduce quinoneimine generated by the oxidation of PAP, regenerating PAP. The deposited silver was collectively converted to a signal by anodic stripping voltammetry. The amount of silver deposited corresponded to the degree of PAP oxidation by redox cycling, which leads to an enhancement of the stripping signal due to the conversion of the product (PAP) and accumulation of the insoluble silver metal. Using carcinoembryonic antigen as a model analyte, the present immunosensing method showed linear behavior over two orders of magnitude with detection limits down to 0.01ng/mL. Dual signal amplification with redox cycling and coulometric signal transduction provides a promising, sensitive, and simple method for the determination of marker proteins.
Source:Biosensors and Bioelectronics, Volume 37, Issue 1
Tomoyuki Yasukawa, Yoshimi Yoshimoto, Takuya Goto, Fumio Mizutani
In this work, a novel immunosensing method has been developed on the basis of the sensitive determination of a product generated by an enzyme reaction with dual amplification system combining an electrochemical-redox cycling and coulometric signal transduction using a galvanic cell. Analytes were captured on microparticles to form sandwich-type immunocomplexes and then labeled with β-galactosidase (β-gal). 4-Aminophenol (PAP) produced by enzyme reaction of β-gal was introduced into the anode compartment consisting of a comb type of an interdigitated array (IDA) electrode. PAP was oxidized at the IDA electrode by the coupled reduction of silver ions at the glassy carbon (GC) electrode of the cathode, resulting in the deposition of silver metal on the GC electrode. The other comb of the IDA electrode was used to reduce quinoneimine generated by the oxidation of PAP, regenerating PAP. The deposited silver was collectively converted to a signal by anodic stripping voltammetry. The amount of silver deposited corresponded to the degree of PAP oxidation by redox cycling, which leads to an enhancement of the stripping signal due to the conversion of the product (PAP) and accumulation of the insoluble silver metal. Using carcinoembryonic antigen as a model analyte, the present immunosensing method showed linear behavior over two orders of magnitude with detection limits down to 0.01ng/mL. Dual signal amplification with redox cycling and coulometric signal transduction provides a promising, sensitive, and simple method for the determination of marker proteins.
Highlights
► Analytes captured on particles were labeled with the enzyme. ► 4-Aminophenol generated was oxidized using a galvanic cell. ► Oxidation of PAP led to the deposition of silver metal in cathode. ► Comb type of the electrode is used to re-produce PAP from its oxidized form. ► Accumulation of silver and recycling of PAP produce a highly amplified stripping signal.Surface plasmon resonance detection of E. coli and methicillin-resistant S. aureus using bacteriophages
11 June 2012,
09:04:54
Publication year:
2012
Source:Biosensors and Bioelectronics, Volume 37, Issue 1
Nancy Tawil, Edward Sacher, Rosemonde Mandeville, Michel Meunier
Early diagnosis and appropriate treatment of Escherichia coli (E. coli) O157:H7 and methicillin-resistant Staphylococcus aureus (MRSA) are key elements in preventing resultant life-threatening illnesses, such as hemorrhagic colitis, hemolytic uremic syndrome, and septicemia. In this report, we describe the use of surface plasmon resonance (SPR) for the biodetection of pathogenic bacteria, using bacteriophages as the recognition elements. T4 bacteriophages were used to detect E. coli, while a novel, highly specific phage was used to detect MRSA. We found that the system permits label-free, real-time, specific, rapid and cost-effective detection of pathogens, for concentrations of 103 colony forming units/milliliter, in less than 20min. This system promises to become a diagnostic tool for bacteria that cause major public concern for food safety, bioterrorism, and nosocomial infections.
Source:Biosensors and Bioelectronics, Volume 37, Issue 1
Nancy Tawil, Edward Sacher, Rosemonde Mandeville, Michel Meunier
Early diagnosis and appropriate treatment of Escherichia coli (E. coli) O157:H7 and methicillin-resistant Staphylococcus aureus (MRSA) are key elements in preventing resultant life-threatening illnesses, such as hemorrhagic colitis, hemolytic uremic syndrome, and septicemia. In this report, we describe the use of surface plasmon resonance (SPR) for the biodetection of pathogenic bacteria, using bacteriophages as the recognition elements. T4 bacteriophages were used to detect E. coli, while a novel, highly specific phage was used to detect MRSA. We found that the system permits label-free, real-time, specific, rapid and cost-effective detection of pathogens, for concentrations of 103 colony forming units/milliliter, in less than 20min. This system promises to become a diagnostic tool for bacteria that cause major public concern for food safety, bioterrorism, and nosocomial infections.
Highlights
► MRSA is the leading cause of nosocomial infections and needs to be detected quickly. ► Antibodies are unstable to environmental fluctuations, costly to produce and cannot distinguish live from death cells. ► A cost effective, robust and easy to produce MRSA-specific phage is isolated. ► An SPR system permits label-free, real-time, specific, rapid and cost-effective detection of pathogens. ► Concentrations as low as 103 colony forming units/milliliter of pathogens are detected in less than 20min.Modulating electron transfer properties of gold nanoparticles for efficient biosensing
11 June 2012,
09:04:54
Publication year:
2012
Source:Biosensors and Bioelectronics, Volume 37, Issue 1
Shikha Sharma, Nidhi Gupta, Sudha Srivastava
Present study concerns modulating the electron transfer properties of gold nanoparticles through amino acid induced coupling among them. In addition to conductivity, the amino functionalization of the nanoparticles results in enhanced activity and operational stability of the biosensor fabricated using the same. Nanoparticles synthesized using amino acid as reducing agent (average diameter—20nm), incorporate the natural coupling property of amino acids and are seen to align in a chain-like arrangement. The coupling of the individual nanoparticles to form chain like structure was confirmed by both absorption spectroscopy as well as transmission electron microscopy. The glucose biosensor developed by adsorption of glucose oxidase (GOx) enzyme onto these coupled gold nanoparticles showed enhanced efficiency as compared to the one with glucose oxidase immobilized onto gold nanoparticles synthesized using the conventional method (trisodium citrate as reducing agent). The fabricated biosensor demonstrated a wide linear concentration range from 1μM–5mM and a high sensitivity of 47.2μAmM−1 cm−2. Also, an enhanced selectivity to glucose was observed with negligible interference in the physiological range, from easily oxidizable biospecies, e.g. uric acid and ascorbic acid. Furthermore, the electrochemical biosensor has excellent long term stability- retaining greater than 85% of the biosensor activity up to 60 days.
Source:Biosensors and Bioelectronics, Volume 37, Issue 1
Shikha Sharma, Nidhi Gupta, Sudha Srivastava
Present study concerns modulating the electron transfer properties of gold nanoparticles through amino acid induced coupling among them. In addition to conductivity, the amino functionalization of the nanoparticles results in enhanced activity and operational stability of the biosensor fabricated using the same. Nanoparticles synthesized using amino acid as reducing agent (average diameter—20nm), incorporate the natural coupling property of amino acids and are seen to align in a chain-like arrangement. The coupling of the individual nanoparticles to form chain like structure was confirmed by both absorption spectroscopy as well as transmission electron microscopy. The glucose biosensor developed by adsorption of glucose oxidase (GOx) enzyme onto these coupled gold nanoparticles showed enhanced efficiency as compared to the one with glucose oxidase immobilized onto gold nanoparticles synthesized using the conventional method (trisodium citrate as reducing agent). The fabricated biosensor demonstrated a wide linear concentration range from 1μM–5mM and a high sensitivity of 47.2μAmM−1 cm−2. Also, an enhanced selectivity to glucose was observed with negligible interference in the physiological range, from easily oxidizable biospecies, e.g. uric acid and ascorbic acid. Furthermore, the electrochemical biosensor has excellent long term stability- retaining greater than 85% of the biosensor activity up to 60 days.
Highlights
► Enhanced electron transfer properties of coupled gold nanoparticles in comparison to spherical gold nanoparticles. ► Improved electron shuttling between enzyme catalytic center and electrode surface. ► Amino acids induced covalently coupled gold nanoparticles. ► Operationally stable biosensor with 15% reduction in activity after 60 days.Biofuel cell as a power source for electronic contact lenses
11 June 2012,
09:04:54
Publication year:
2012
Source:Biosensors and Bioelectronics, Volume 37, Issue 1
Magnus Falk, Viktor Andoralov, Zoltan Blum, Javier Sotres, Dmitry B. Suyatin, Tautgirdas Ruzgas, Thomas Arnebrant, Sergey Shleev
Here we present unequivocal experimental proof that microscale cofactor- and membrane-less, direct electron transfer based enzymatic fuel cells do produce significant amounts of electrical energy in human lachrymal liquid (tears). 100μm diameter gold wires, covered with 17nm gold nanoparticles, were used to fashion three-dimensional nanostructured microelectrodes, which were biomodified with Corynascus thermophilus cellobiose dehydrogenase and Myrothecium verrucaria bilirubin oxidase as anodic and cathodic bioelements, respectively. The following characteristics of miniature glucose/oxygen biodevices operating in human tears were registered: 0.57V open-circuit voltage, about 1μWcm−2 maximum power density at a cell voltage of 0.5V, and more than 20h operational half-life. Theoretical calculations regarding the maximum recoverable electrical energy can be extracted from the biofuel and the biooxidant, glucose and molecular oxygen, each readily available in human lachrymal liquid, fully support our belief that biofuel cells can be used as electrical power sources for so called smart contact lenses.
Source:Biosensors and Bioelectronics, Volume 37, Issue 1
Magnus Falk, Viktor Andoralov, Zoltan Blum, Javier Sotres, Dmitry B. Suyatin, Tautgirdas Ruzgas, Thomas Arnebrant, Sergey Shleev
Here we present unequivocal experimental proof that microscale cofactor- and membrane-less, direct electron transfer based enzymatic fuel cells do produce significant amounts of electrical energy in human lachrymal liquid (tears). 100μm diameter gold wires, covered with 17nm gold nanoparticles, were used to fashion three-dimensional nanostructured microelectrodes, which were biomodified with Corynascus thermophilus cellobiose dehydrogenase and Myrothecium verrucaria bilirubin oxidase as anodic and cathodic bioelements, respectively. The following characteristics of miniature glucose/oxygen biodevices operating in human tears were registered: 0.57V open-circuit voltage, about 1μWcm−2 maximum power density at a cell voltage of 0.5V, and more than 20h operational half-life. Theoretical calculations regarding the maximum recoverable electrical energy can be extracted from the biofuel and the biooxidant, glucose and molecular oxygen, each readily available in human lachrymal liquid, fully support our belief that biofuel cells can be used as electrical power sources for so called smart contact lenses.
Highlights
► A three-dimensional microscale biocathodes and bioanodes were fabricated and characterised. ► Miniature direct electron transfer based enzymatic fuel cells were designed. ► Their performance was investigated in human lachrymal liquid (tears). ► Theoretical calculations regarding the recoverable electrical energy in tears were carried out.Bi-enzyme l-arginine-selective amperometric biosensor based on ammonium-sensing polyaniline-modified electrode
11 June 2012,
09:04:54
Publication year:
2012
Source:Biosensors and Bioelectronics, Volume 37, Issue 1
Nataliya Stasyuk, Oleh Smutok, Galina Gayda, Bohdan Vus, Yevgen Koval'chuk, Mykhailo Gonchar
A novel l-arginine-selective amperometric bi-enzyme biosensor based on recombinant human arginase I isolated from the gene-engineered strain of methylotrophic yeast Hansenula polymorpha and commercial urease is described. The biosensing layer was placed onto a polyaniline–Nafion composite platinum electrode and covered with a calcium alginate gel. The developed sensor revealed a good selectivity to l-arginine. The sensitivity of the biosensor was 110±1.3nA/(mMmm2) with the apparent Michaelis–Menten constant (K M app) derived from an l-arginine (l-Arg) calibration curve of 1.27±0.29mM. A linear concentration range was observed from 0.07 to 0.6mM, a limit of detection being 0.038mM and a response time — 10s. The developed biosensor demonstrated good storage stability. A laboratory prototype of the proposed amperometric biosensor was applied to the samples of three commercial pharmaceuticals (“Tivortin”, “Cytrarginine”, “Aminoplazmal 10% E”) for l-Arg testing. The obtained l-Arg-content values correlated well with those declared by producers.
Source:Biosensors and Bioelectronics, Volume 37, Issue 1
Nataliya Stasyuk, Oleh Smutok, Galina Gayda, Bohdan Vus, Yevgen Koval'chuk, Mykhailo Gonchar
A novel l-arginine-selective amperometric bi-enzyme biosensor based on recombinant human arginase I isolated from the gene-engineered strain of methylotrophic yeast Hansenula polymorpha and commercial urease is described. The biosensing layer was placed onto a polyaniline–Nafion composite platinum electrode and covered with a calcium alginate gel. The developed sensor revealed a good selectivity to l-arginine. The sensitivity of the biosensor was 110±1.3nA/(mMmm2) with the apparent Michaelis–Menten constant (K M app) derived from an l-arginine (l-Arg) calibration curve of 1.27±0.29mM. A linear concentration range was observed from 0.07 to 0.6mM, a limit of detection being 0.038mM and a response time — 10s. The developed biosensor demonstrated good storage stability. A laboratory prototype of the proposed amperometric biosensor was applied to the samples of three commercial pharmaceuticals (“Tivortin”, “Cytrarginine”, “Aminoplazmal 10% E”) for l-Arg testing. The obtained l-Arg-content values correlated well with those declared by producers.
Graphical abstract
Graphical Abstract
Calibration curve for amperometric response on l-Arg of the developed bi-enzyme PANi-Nafion/Pt electrode. Inset: chronoamperometric current response upon subsequent additions of L-Arg. Conditions: −200mV vs Ag/AgCl electrode in 30mM Phosphate buffer, pH 7.5 at 22°C.Comparison of sensing strategies in SPR biosensor for rapid and sensitive enumeration of bacteria
11 June 2012,
09:04:54
Publication year:
2012
Source:Biosensors and Bioelectronics, Volume 37, Issue 1
Özlem Torun, İsmail Hakkı Boyacı, Erhan Temür, Uğur Tamer
Rapid and sensitive detections of microorganisms are very important for biodefence, food safety, medical diagnosis and pharmaceutics. The present study aims to find out the most proper bioactive surface preparation method to develop rapid, sensitive and selective bacteria biosensor, based on surface plasmon resonance (SPR) spectroscopy. Escherichia coli (E. coli) was used as a model bacterium and four sensing strategies in SPR were tested. Three of these strategies are antibody immobilization methods that are non-specific adsorption, specific adsorption via the avidin–biotin interaction, and immobilization of antibodies via self-assembled monolayer formation. The fourth strategy is a novel method for bacteria enumeration based on the combination of the SPR spectroscopy and immunomagnetic separation with using gold-coated magnetic nanoparticles. According to results, the most efficient SPR method is the one based on gold-coated magnetic nanoparticles. This method allows to specifically separate E. coli from the environment and to quantify rapidly without any labeling procedure. The developed method has a linear range between 30 and 3.0×104 cfu/ml, and a detection limit of 3cfu/ml. The selectivity of the method was examined with Enterobacter aerogenes and Enterobacter dissolvens, which did not produce any significant response. The usefulness of the method to detect E. coli in real water samples was also investigated, and the results were compared with the results from plate-counting method. There was no significant difference between the methods (p>0.05).
Source:Biosensors and Bioelectronics, Volume 37, Issue 1
Özlem Torun, İsmail Hakkı Boyacı, Erhan Temür, Uğur Tamer
Rapid and sensitive detections of microorganisms are very important for biodefence, food safety, medical diagnosis and pharmaceutics. The present study aims to find out the most proper bioactive surface preparation method to develop rapid, sensitive and selective bacteria biosensor, based on surface plasmon resonance (SPR) spectroscopy. Escherichia coli (E. coli) was used as a model bacterium and four sensing strategies in SPR were tested. Three of these strategies are antibody immobilization methods that are non-specific adsorption, specific adsorption via the avidin–biotin interaction, and immobilization of antibodies via self-assembled monolayer formation. The fourth strategy is a novel method for bacteria enumeration based on the combination of the SPR spectroscopy and immunomagnetic separation with using gold-coated magnetic nanoparticles. According to results, the most efficient SPR method is the one based on gold-coated magnetic nanoparticles. This method allows to specifically separate E. coli from the environment and to quantify rapidly without any labeling procedure. The developed method has a linear range between 30 and 3.0×104 cfu/ml, and a detection limit of 3cfu/ml. The selectivity of the method was examined with Enterobacter aerogenes and Enterobacter dissolvens, which did not produce any significant response. The usefulness of the method to detect E. coli in real water samples was also investigated, and the results were compared with the results from plate-counting method. There was no significant difference between the methods (p>0.05).
Highlights
► Four sensing strategies in SPR biosensor were tested and compared for E. coli enumeration. ► The most sensitive and rapid method was the one based on gold-coated magnetic nanoparticles. ► With this method, the linear range was obtained between 30 and 3.0×104 cfu/ml. ► The limit of detection was found to be as 3cfu/ml. ► E. coli determination was also realized for the real water samples with the developed method.Graphene oxide based fluorescent aptasensor for adenosine deaminase detection using adenosine as the substrate
11 June 2012,
09:04:54
Publication year:
2012
Source:Biosensors and Bioelectronics, Volume 37, Issue 1
Xiao-Jing Xing, Xue-Guo Liu, Yue-He, Qing-Ying Luo, Hong-Wu Tang, Dai-Wen Pang
We present a novel fluorescent aptasensor for simple and accurate detection of adenosine deaminase (ADA) activity and inhibition on the basis of graphene oxide (GO) using adenosine (AD) as the substrate. This aptasensor consists of a dye-labeled single-stranded AD specific aptamer, GO and AD. The fluorescence intensity of the dye-labeled AD specific aptamer is quenched very efficiently by GO as a result of strong π–π stacking interaction and excellent electronic transference of GO. In the presence of AD, the fluorescence of the GO-based probe is recovered since the competitive binding of AD and GO with the dye-labeled aptamer prevents the adsorption of dye-labeled aptamer on GO. When ADA was introduced to this GO-based probe solution, the fluorescence of the probe was quenched owing to ADA can convert AD into inosine which has no affinity to the dye-labeled aptamer, thus allowing quantitative investigation of ADA activity. The as-proposed sensor is highly selective and sensitive for the assay of ADA activity with a detection limit of 0.0129U/mL in clean buffer, which is more than one order of magnitude lower than the previous reports. Meanwhile, a good linear relationship with the correlation coefficient of R=0.9922 was obtained by testing 5% human serum containing a series of concentrations of ADA. Additionally, the inhibition effect of erythro-9-(2-hydroxy-3-nonyl) adenine on ADA activity was investigated in this design. The GO-based fluorescence aptasensor not only provides a simple, cost-effective and sensitive platform for the detection of ADA and its inhibitor but also shows great potential in the diagnosis of ADA-relevant diseases and drug development.
Source:Biosensors and Bioelectronics, Volume 37, Issue 1
Xiao-Jing Xing, Xue-Guo Liu, Yue-He, Qing-Ying Luo, Hong-Wu Tang, Dai-Wen Pang
We present a novel fluorescent aptasensor for simple and accurate detection of adenosine deaminase (ADA) activity and inhibition on the basis of graphene oxide (GO) using adenosine (AD) as the substrate. This aptasensor consists of a dye-labeled single-stranded AD specific aptamer, GO and AD. The fluorescence intensity of the dye-labeled AD specific aptamer is quenched very efficiently by GO as a result of strong π–π stacking interaction and excellent electronic transference of GO. In the presence of AD, the fluorescence of the GO-based probe is recovered since the competitive binding of AD and GO with the dye-labeled aptamer prevents the adsorption of dye-labeled aptamer on GO. When ADA was introduced to this GO-based probe solution, the fluorescence of the probe was quenched owing to ADA can convert AD into inosine which has no affinity to the dye-labeled aptamer, thus allowing quantitative investigation of ADA activity. The as-proposed sensor is highly selective and sensitive for the assay of ADA activity with a detection limit of 0.0129U/mL in clean buffer, which is more than one order of magnitude lower than the previous reports. Meanwhile, a good linear relationship with the correlation coefficient of R=0.9922 was obtained by testing 5% human serum containing a series of concentrations of ADA. Additionally, the inhibition effect of erythro-9-(2-hydroxy-3-nonyl) adenine on ADA activity was investigated in this design. The GO-based fluorescence aptasensor not only provides a simple, cost-effective and sensitive platform for the detection of ADA and its inhibitor but also shows great potential in the diagnosis of ADA-relevant diseases and drug development.
Highlights
► A novel fluorescence method for adenosine deaminase (ADA) and its inhibitor assay was developed. ► This approach was based on graphene oxide and adenosine was used as the substrate. ► This assay only requires one labeled DNA probe, making the assay more cost-effective. ► A low detection limit (0.0129U/mL) was obtained. ► The approach was applied to determine ADA in real human serum sample.Amplified surface plasmon resonance immunosensor for interferon-Gamma based on a streptavidin-incorporated aptamer
11 June 2012,
09:04:54
Publication year:
2012
Source:Biosensors and Bioelectronics, Volume 37, Issue 1
Chia-Chen Chang, Shenhsiung Lin, Chung-Han Lee, Tsung-Liang Chuang, Po-Ren Hsueh, Hsin-Chih Lai, Chii-Wann Lin
Interferon-gamma (IFN-γ) is associated with susceptibility to tuberculosis, which is a major public health problem worldwide. Although significant progress has been made with regard to the design of enzyme immunoassays for IFN-γ, this assay is still labor-intensive and time-consuming. We therefore designed a DNA aptamer hairpin structure for the detection of IFN-γ with high sensitivity and selectivity. A streptavidin DNA aptamer was incorporated into the IFN-γ binding aptamer probe for the amplified detection of the target molecules. Initially, the probe remained in the inactive configuration. The addition of IFN-γ induced the rearrangement of the aptamer structure, allowing the self-assembly of the active streptavidin aptamer conformation for the streptavidin molecular recognition. Under optimized conditions, the detection limit was determined to be 33pM, with a dynamic range from 0.3 to 333nM, both of which were superior to those of corresponding optical sensors. Because combined aptamers are composed of nucleic acids, this optical aptasensor provided the advantages of high sensitivity, simplicity, reusability, and no further labeling or sample pre-treatment.
Source:Biosensors and Bioelectronics, Volume 37, Issue 1
Chia-Chen Chang, Shenhsiung Lin, Chung-Han Lee, Tsung-Liang Chuang, Po-Ren Hsueh, Hsin-Chih Lai, Chii-Wann Lin
Interferon-gamma (IFN-γ) is associated with susceptibility to tuberculosis, which is a major public health problem worldwide. Although significant progress has been made with regard to the design of enzyme immunoassays for IFN-γ, this assay is still labor-intensive and time-consuming. We therefore designed a DNA aptamer hairpin structure for the detection of IFN-γ with high sensitivity and selectivity. A streptavidin DNA aptamer was incorporated into the IFN-γ binding aptamer probe for the amplified detection of the target molecules. Initially, the probe remained in the inactive configuration. The addition of IFN-γ induced the rearrangement of the aptamer structure, allowing the self-assembly of the active streptavidin aptamer conformation for the streptavidin molecular recognition. Under optimized conditions, the detection limit was determined to be 33pM, with a dynamic range from 0.3 to 333nM, both of which were superior to those of corresponding optical sensors. Because combined aptamers are composed of nucleic acids, this optical aptasensor provided the advantages of high sensitivity, simplicity, reusability, and no further labeling or sample pre-treatment.
Highlights
► We developed a hairpin-shaped bi-specific aptamer probe for the sensitive detection of INF-γ. ► The probe was comprised of an INF-γ-binding aptamer and a streptavidin-binding aptamer. ► The binding of streptavidin to this probe resulted in the enhancement of the SPR assay.Covalent conjugation of avidin with dye-doped silica nanopaticles and preparation of high density avidin nanoparticles as photostable bioprobes
11 June 2012,
09:04:54
Publication year:
2012
Source:Biosensors and Bioelectronics, Volume 37, Issue 1
Ze-Zhong Chen, Li Cai, Xiao-Min Dong, Hong-Wu Tang, Dai-Wen Pang
Progress in biomedical imaging depends on the development of bioprobes with a high sensitivity and stability. Fluorescent silica nanoparticles (NPs) covalent conjugation of avidin has been proposed for cancer cells imaging by fluorescence microscopy. Uniform silica NPs were prepared using water-in-oil (W/O) microemulsion methods and primary amine groups were introduced onto the surface of the NPs by condensation of tetraethyl orthosilicate (TEOS). Optically stable organic dyes, tris(2,2'-bipyridyl) dichlororuthenium(II) hexahydrate (Rubpy), were doped inside the silica NPs. The amine functions were transferred to carboxyl groups coupled with a linker elongation. Avidin was immobilized at the surface of the NPs by covalent binding to the carboxyl linkers. The binding capacity of the avidin-covered NPs for ligand biotin was quantified by titration with biotin(5-fluorescein) conjugate to 1.25 biotin binding sites/100nm2. We used biotinylated antibody and cell recognition by fluorescence microscopy imaging technique. The lung carcinoma cells were identified easily with high efficiency using these antibody-coated NPs. By comparison with fluorescein isothiocyanate (FITC), dye-doped silica NPs display dramatically increased stability of fluorescence as well as photostability, as compared to the common organic dye, when under continuous irradiation.
Source:Biosensors and Bioelectronics, Volume 37, Issue 1
Ze-Zhong Chen, Li Cai, Xiao-Min Dong, Hong-Wu Tang, Dai-Wen Pang
Progress in biomedical imaging depends on the development of bioprobes with a high sensitivity and stability. Fluorescent silica nanoparticles (NPs) covalent conjugation of avidin has been proposed for cancer cells imaging by fluorescence microscopy. Uniform silica NPs were prepared using water-in-oil (W/O) microemulsion methods and primary amine groups were introduced onto the surface of the NPs by condensation of tetraethyl orthosilicate (TEOS). Optically stable organic dyes, tris(2,2'-bipyridyl) dichlororuthenium(II) hexahydrate (Rubpy), were doped inside the silica NPs. The amine functions were transferred to carboxyl groups coupled with a linker elongation. Avidin was immobilized at the surface of the NPs by covalent binding to the carboxyl linkers. The binding capacity of the avidin-covered NPs for ligand biotin was quantified by titration with biotin(5-fluorescein) conjugate to 1.25 biotin binding sites/100nm2. We used biotinylated antibody and cell recognition by fluorescence microscopy imaging technique. The lung carcinoma cells were identified easily with high efficiency using these antibody-coated NPs. By comparison with fluorescein isothiocyanate (FITC), dye-doped silica NPs display dramatically increased stability of fluorescence as well as photostability, as compared to the common organic dye, when under continuous irradiation.
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