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Nanopore sensors: From hybrid to abiotic systems
01 August 2012,
10:42:44
Publication year:
2012
Source:Biosensors and Bioelectronics, Volume 38, Issue 1
Armagan Kocer, Lara Tauk, Philippe Déjardin
The use of nanopores of well controlled geometry for sensing molecules in solution is reviewed. Focus is concentrated especially on synthetic track-etch pores in polymer foils and on biological nanopores, i.e. ion channels. After a brief section about multipore sensors, specific attention is provided to works relative to a single nanopore sensor. The different strategies to combine the robustness of supports with the high selectivity of the biological channels are reviewed. The scope ranges from keeping the membrane natural environment of biological channels in supported and suspended bilayer membranes, to considering completely abiotic designed nanopores created through synthetic materials. The α-hemolysine channel and the mechanosensitive channel of large conductance with their modifications are especially considered in the first strategy, the conical functionalized nanopores created in polymer foils in the second one. The different attempts of reading macromolecules are also discussed. A third hybrid strategy, which was not extensively explored, consists in the inclusion of a biological structure into a well-designed nanopore through the support, as recently with gramicidin.
Source:Biosensors and Bioelectronics, Volume 38, Issue 1
Armagan Kocer, Lara Tauk, Philippe Déjardin
The use of nanopores of well controlled geometry for sensing molecules in solution is reviewed. Focus is concentrated especially on synthetic track-etch pores in polymer foils and on biological nanopores, i.e. ion channels. After a brief section about multipore sensors, specific attention is provided to works relative to a single nanopore sensor. The different strategies to combine the robustness of supports with the high selectivity of the biological channels are reviewed. The scope ranges from keeping the membrane natural environment of biological channels in supported and suspended bilayer membranes, to considering completely abiotic designed nanopores created through synthetic materials. The α-hemolysine channel and the mechanosensitive channel of large conductance with their modifications are especially considered in the first strategy, the conical functionalized nanopores created in polymer foils in the second one. The different attempts of reading macromolecules are also discussed. A third hybrid strategy, which was not extensively explored, consists in the inclusion of a biological structure into a well-designed nanopore through the support, as recently with gramicidin.
Highlights
► Different strategies used in producing pores of controlled geometry are described. ► Ways to include biological or bioinspired channels in bilayer membranes are recalled. ► Focus on single pore devices and on robust supports like track-etch polymer foils.CuO thin film based uric acid biosensor with enhanced response characteristics
01 August 2012,
10:42:44
Publication year:
2012
Source:Biosensors and Bioelectronics, Volume 38, Issue 1
Kajal Jindal, Monika Tomar, Vinay Gupta
An efficient reagentless uric acid biosensor has been realized using a copper oxide (CuO) thin film matrix grown onto platinum (Pt) coated corning glass substrates by pulsed laser deposition (PLD) technique. The p-type CuO matrix successfully introduces redox property in the electrode and provides enhanced electron communication features. Sensing response obtained by the bioelectrocatalytic oxidation of uric acid by uricase/CuO/Pt/glass electrode was studied without any external mediator using cyclic voltammetry (CV) and photometric assay. The studies reveal that the uricase/CuO/Pt/glass bio-electrode exhibits good linearity over a wide range of 0.05mM to 1.0mM uric acid concentration with enhanced response of 2.7mA/mM and high shelf life (>14 weeks). A low Michaelis–Menten constant (K m ) of 0.12mM, indicate that the immobilized enzyme (uricase) has enhanced affinity towards its analyte (uric acid). The results confirm promising application of the p-type CuO thin film matrix for the realization of a reagentless integrated implantable biosensor.
Source:Biosensors and Bioelectronics, Volume 38, Issue 1
Kajal Jindal, Monika Tomar, Vinay Gupta
An efficient reagentless uric acid biosensor has been realized using a copper oxide (CuO) thin film matrix grown onto platinum (Pt) coated corning glass substrates by pulsed laser deposition (PLD) technique. The p-type CuO matrix successfully introduces redox property in the electrode and provides enhanced electron communication features. Sensing response obtained by the bioelectrocatalytic oxidation of uric acid by uricase/CuO/Pt/glass electrode was studied without any external mediator using cyclic voltammetry (CV) and photometric assay. The studies reveal that the uricase/CuO/Pt/glass bio-electrode exhibits good linearity over a wide range of 0.05mM to 1.0mM uric acid concentration with enhanced response of 2.7mA/mM and high shelf life (>14 weeks). A low Michaelis–Menten constant (K m ) of 0.12mM, indicate that the immobilized enzyme (uricase) has enhanced affinity towards its analyte (uric acid). The results confirm promising application of the p-type CuO thin film matrix for the realization of a reagentless integrated implantable biosensor.
Highlights
► Article is focused on the development of a reagentless uric acid biosensor. ► Biosensing is based on the bioelectrocatalytic oxidation of uric acid by uricase. ► CuO matrix introduces redox property for charge transfer eliminating need for external mediator. ► Uricase/CuO/Pt/glass bio-electrode shows a fast and good linear response. ► A low K m of 0.12mM is observed with enhanced sensing response (sensitivity-2.7mA/mM).A 3D localized surface plasmon resonance biosensor for the study of trivalent arsenic binding to the ArsA ATPase
01 August 2012,
10:42:44
Publication year:
2012
Source:Biosensors and Bioelectronics, Volume 38, Issue 1
Chang Liu, Vittoria Balsamo, Dali Sun, Melodie Naja, Xuemei Wang, Barry Rosen, Chen-Zhong Li
A self-assembled 3D hydrogel–nanoparticle composite integrated surface plasmon resonance (SPR) sensor is reported here. The novel assembled substrate was developed by means of a surface mediated radical co-polymerization process to obtain a highly sensitive hydrogel-based thin film that possesses specific binding sites for target analytes. Initially, amino group modified gold nanoparticles (AuNPs) were covalently linked to acrylic acid monomer. Following this, N-isopropylacrylamide (NIPAAm) and AuNPs linked acrylic acid (AAc) monomers were randomly co-polymerized by the “grafting from” method in the presence of initiator and crosslinker onto the sensing surface. Surface charecterization techniques were utilized to evaluate the thickness and composition of the hydrogel-nanoparticle film. The sensing platform was employed to study the binding kinetics and conformational changes of the ArsA ATPase as a consequence of binding trivalent arsenicals under a variety of conditions. ArsA, the catalytic subunit of the ArsAB arsenite (As(III)) translocating ATPase, is one of the five proteins encoded by the arsenical resistance (ars) operon of plasmid R773 in cells of Escherichia coli, that confers resistance to trivalent and pentavalent salts of the metalloid arsenic. SPR measurements indicate that the 3D hydrogel-nanoparticle coated sensors exhibited a higher sensitivity than that of the 2D AuNPs decorated sensors. Binding of As(III) to ArsA is greatly facilitated by the presence of magnesium ion and ATP.
Source:Biosensors and Bioelectronics, Volume 38, Issue 1
Chang Liu, Vittoria Balsamo, Dali Sun, Melodie Naja, Xuemei Wang, Barry Rosen, Chen-Zhong Li
A self-assembled 3D hydrogel–nanoparticle composite integrated surface plasmon resonance (SPR) sensor is reported here. The novel assembled substrate was developed by means of a surface mediated radical co-polymerization process to obtain a highly sensitive hydrogel-based thin film that possesses specific binding sites for target analytes. Initially, amino group modified gold nanoparticles (AuNPs) were covalently linked to acrylic acid monomer. Following this, N-isopropylacrylamide (NIPAAm) and AuNPs linked acrylic acid (AAc) monomers were randomly co-polymerized by the “grafting from” method in the presence of initiator and crosslinker onto the sensing surface. Surface charecterization techniques were utilized to evaluate the thickness and composition of the hydrogel-nanoparticle film. The sensing platform was employed to study the binding kinetics and conformational changes of the ArsA ATPase as a consequence of binding trivalent arsenicals under a variety of conditions. ArsA, the catalytic subunit of the ArsAB arsenite (As(III)) translocating ATPase, is one of the five proteins encoded by the arsenical resistance (ars) operon of plasmid R773 in cells of Escherichia coli, that confers resistance to trivalent and pentavalent salts of the metalloid arsenic. SPR measurements indicate that the 3D hydrogel-nanoparticle coated sensors exhibited a higher sensitivity than that of the 2D AuNPs decorated sensors. Binding of As(III) to ArsA is greatly facilitated by the presence of magnesium ion and ATP.
Highlights:
► We developed a 3D hydrogel-nanoparticle sensing platform for Localized Surface Plasmon Resonance. ► We demonstrated the enhanced sensitivity for protein binding study using the 3D structured sensor. ► The binding kinetics of the arsenic detoxifying systems is quantitatively investigated. ► We investigated pathway of As(III) binding to ArsA protein using the LSPR sensing system. ► We demonstrated a direct channeling of As(III) transfer from ArsD to ArsA.A novel sensor based on electrochemical polymerization of diglycolic acid for determination of acetaminophen
01 August 2012,
10:42:44
Publication year:
2012
Source:Biosensors and Bioelectronics, Volume 38, Issue 1
Fen Xu, Hui-Ying Ru, Li-Xian Sun, Yong-Jin Zou, Cheng-Li Jiao, Tao-Yi Wang, Jia-Ming Zhang, Qian Zheng, Huai-Ying Zhou
Diglycolic acid (DA) polymer was coated on glassy carbon (GC) electrode by cyclic voltammetry (CV) technique for the first time. The electrochemical performances of the modified electrode were investigated by CV and electrochemical impedance (EIS). The obtained electrode showed an excellent electrocatalytic activity for the oxidation of acetaminophen (ACOP). A couple of well-defined reversible electrochemical redox peaks were observed on the ploy(DA)/GC electrode in ACOP solution. Compared with bare GC electrode, the oxidation peak potential of ACOP on ploy(DA)/GC electrode moved from 0.289V to 0.220V. Meanwhile, the oxidation peak current was much higher on the modified electrode than that on the bare GC electrode, indicating DA polymer modified electrode possessed excellent performance for the oxidation of ACOP. This kind of capability of the modified electrode can be enlisted for the highly sensitive and selective determination of ACOP. Under the optimized conditions, a wide linear range from 2×10−8 to 5.0×10−4 M with a correlation coefficient 0.9995 was obtained. The detection limit was 6.7×10−9 M (at the ratio of signal to noise, S/N=3:1). The modified electrode also exhibited very good stability and reproducibility for the detection of ACOP. The established method was applied to the determination of ACOP in samples. An average recovery of 100.1% was achieved. These results indicated that this method was reliable for determining ACOP.
Source:Biosensors and Bioelectronics, Volume 38, Issue 1
Fen Xu, Hui-Ying Ru, Li-Xian Sun, Yong-Jin Zou, Cheng-Li Jiao, Tao-Yi Wang, Jia-Ming Zhang, Qian Zheng, Huai-Ying Zhou
Diglycolic acid (DA) polymer was coated on glassy carbon (GC) electrode by cyclic voltammetry (CV) technique for the first time. The electrochemical performances of the modified electrode were investigated by CV and electrochemical impedance (EIS). The obtained electrode showed an excellent electrocatalytic activity for the oxidation of acetaminophen (ACOP). A couple of well-defined reversible electrochemical redox peaks were observed on the ploy(DA)/GC electrode in ACOP solution. Compared with bare GC electrode, the oxidation peak potential of ACOP on ploy(DA)/GC electrode moved from 0.289V to 0.220V. Meanwhile, the oxidation peak current was much higher on the modified electrode than that on the bare GC electrode, indicating DA polymer modified electrode possessed excellent performance for the oxidation of ACOP. This kind of capability of the modified electrode can be enlisted for the highly sensitive and selective determination of ACOP. Under the optimized conditions, a wide linear range from 2×10−8 to 5.0×10−4 M with a correlation coefficient 0.9995 was obtained. The detection limit was 6.7×10−9 M (at the ratio of signal to noise, S/N=3:1). The modified electrode also exhibited very good stability and reproducibility for the detection of ACOP. The established method was applied to the determination of ACOP in samples. An average recovery of 100.1% was achieved. These results indicated that this method was reliable for determining ACOP.
Highlights
► Diglycolic acid polymer coated on glassy carbon electrode by cyclic voltammetry. ► Modified electrode has an excellent electrocatalytic activity for acetaminophen. ► A wide linear range is from 2×10−8 to 5.0×10−4 M. ► The detection limit is 6.7×10−9 M.A graphene oxide based biosensor for microcystins detection by fluorescence resonance energy transfer
01 August 2012,
10:42:44
Publication year:
2012
Source:Biosensors and Bioelectronics, Volume 38, Issue 1
Yan Shi, Jiazhen Wu, Yujing Sun, Yue Zhang, Zhiwei Wen, Haichao Dai, Hongda Wang, Zhuang Li
Water safety is one of the most pervasive problems afflicting people throughout the world. Microcystin, a hepatotoxin produced by cyanobacteria, poses a growing and serious threat of water safety. According to World Health Organization (WHO), the limit of content of microcystin-LR (MC-LR) in drinking water is as low as 1μg/L; it is thus necessary to explore a sensitive method for the trace detection of microcystins (MCs). Based on the observation of gold nanoparticles (Au NPs) induced graphene oxide (GO) fluorescence quenching, a reliable biosensor was developed here for microcystins detection. MCs could be attached on Au NPs through the interaction with single strand-DNA (ss-DNA) modified on Au NPs, which formed Au–DNA–MCs complexes. These MCs in the complexes could be immunologically recognized by the antibodies adsorbed on GO sheets, as a result, Au NPs were close enough to quench the photoluminescence of GO by the fluorescence resonance energy transfer (FRET). The fluorescence intensity decreased with the increase of MCs as more Au NPs linked onto GO surface. The limit of detection was 0.5 and 0.3μg/L for microcystin-LR and microcystin-RR (MC-RR), respectively, which satisfies the strictest standard of WHO. Well defined results were also obtained in natural lake water and the specificity experiment. The antibody used here could recognize Adda group, the conservative part of MCs, which allowed the biosensor to detect both single toxin and the total content of MCs existing in the water sample.
Source:Biosensors and Bioelectronics, Volume 38, Issue 1
Yan Shi, Jiazhen Wu, Yujing Sun, Yue Zhang, Zhiwei Wen, Haichao Dai, Hongda Wang, Zhuang Li
Water safety is one of the most pervasive problems afflicting people throughout the world. Microcystin, a hepatotoxin produced by cyanobacteria, poses a growing and serious threat of water safety. According to World Health Organization (WHO), the limit of content of microcystin-LR (MC-LR) in drinking water is as low as 1μg/L; it is thus necessary to explore a sensitive method for the trace detection of microcystins (MCs). Based on the observation of gold nanoparticles (Au NPs) induced graphene oxide (GO) fluorescence quenching, a reliable biosensor was developed here for microcystins detection. MCs could be attached on Au NPs through the interaction with single strand-DNA (ss-DNA) modified on Au NPs, which formed Au–DNA–MCs complexes. These MCs in the complexes could be immunologically recognized by the antibodies adsorbed on GO sheets, as a result, Au NPs were close enough to quench the photoluminescence of GO by the fluorescence resonance energy transfer (FRET). The fluorescence intensity decreased with the increase of MCs as more Au NPs linked onto GO surface. The limit of detection was 0.5 and 0.3μg/L for microcystin-LR and microcystin-RR (MC-RR), respectively, which satisfies the strictest standard of WHO. Well defined results were also obtained in natural lake water and the specificity experiment. The antibody used here could recognize Adda group, the conservative part of MCs, which allowed the biosensor to detect both single toxin and the total content of MCs existing in the water sample.
Highlights
► Based on the observation of gold nanoparticles (Au NPs) induced graphene oxide (GO) fluorescence quenching, a reliable MCs biosensor was developed here for microcystins detection. ► Limit of detection was 0.5 and 0.3μg/L for MC-LR and MC-RR, respectively, which satisfies the strictest standard of WHO. ► Well defined results were also obtained in natural lake water and the specificity experiment.Signal amplification architecture for electrochemical aptasensor based on network-like thiocyanuric acid/gold nanoparticle/ssDNA
01 August 2012,
10:42:44
Publication year:
2012
Source:Biosensors and Bioelectronics, Volume 38, Issue 1
Zhengbo Chen, Lidong Li, Yu Tian, Xiaojiao Mu, Lin Guo
In this work, we described signal amplification architecture for electronic aptamer-based sensor (E-AB), which is applicable to a wide range of aptamers. Herein, we only take lysozyme as the representative sensing target. The amplification method was based on the network of thiocyanuric acid (TCA)/gold nanoparticles (AuNPs) modified with ssDNA. The binding event can be detected by a decrease in the integrated charge of the surface-bound [Ru(NH3)6]3+ which electrostatically absorbed onto the negatively charged phosphate backbones of DNA. In the presence of target molecules, a large amount of TCA/AuNP/ssDNA network associated with [Ru(NH3)6]3+ would be removed from the electrode surface, leading to a significant decrease of redox current. Cyclic voltammetry (CV) signals of [Ru(NH3)6]3+ provides quantitative measures of the concentrations of lysozyme, with a linear calibration ranging from 5pM to 1nM and a detection limit is 0.1pM. The detection limit of the proposed sensor is one order of magnitude and three orders of magnitude more sensitive than the detection limits in the absence of TCA (5pM) and in the absence of TCA/AuNP/ssDNA network (0.5nM). This amplification method is promising for broad potential application in clinic assay and various protein analysis.
Source:Biosensors and Bioelectronics, Volume 38, Issue 1
Zhengbo Chen, Lidong Li, Yu Tian, Xiaojiao Mu, Lin Guo
In this work, we described signal amplification architecture for electronic aptamer-based sensor (E-AB), which is applicable to a wide range of aptamers. Herein, we only take lysozyme as the representative sensing target. The amplification method was based on the network of thiocyanuric acid (TCA)/gold nanoparticles (AuNPs) modified with ssDNA. The binding event can be detected by a decrease in the integrated charge of the surface-bound [Ru(NH3)6]3+ which electrostatically absorbed onto the negatively charged phosphate backbones of DNA. In the presence of target molecules, a large amount of TCA/AuNP/ssDNA network associated with [Ru(NH3)6]3+ would be removed from the electrode surface, leading to a significant decrease of redox current. Cyclic voltammetry (CV) signals of [Ru(NH3)6]3+ provides quantitative measures of the concentrations of lysozyme, with a linear calibration ranging from 5pM to 1nM and a detection limit is 0.1pM. The detection limit of the proposed sensor is one order of magnitude and three orders of magnitude more sensitive than the detection limits in the absence of TCA (5pM) and in the absence of TCA/AuNP/ssDNA network (0.5nM). This amplification method is promising for broad potential application in clinic assay and various protein analysis.
Highlights
► This paper presents a signal amplification method for any electrochemical aptasensors. ► The amplification approach is based on thiocyanuric acid-gold nanoparticles network. ► Such an aptasensor opens a rapid, selective and sensitive route for clinical assay.Highly sensitive visible light activated photoelectrochemical biosensing of organophosphate pesticide using biofunctional crossed bismuth oxyiodide flake arrays
01 August 2012,
10:42:44
Publication year:
2012
Source:Biosensors and Bioelectronics, Volume 38, Issue 1
Jingming Gong, Xiaoqing Wang, Xue Li, Kewei Wang
A new, highly sensitive and selective biosensor for the photoelectrochemical (PEC) detection of organophosphate pesticides (OPs) has been developed, whereby newly synthesized crossed bismuth oxyiodide (BiOI) nanoflake arrays (BiOINFs) are fabricated as a photoactive electrode via a successive ionic layer adsorption and reaction (SILAR) approach. The smart integration of BiOINFs with biomolecules acetylcholinesterase (AChE) yields a novel AChE–BiOINFs hybrid, constructing a three-dimensional (3D) porous network biosensing platform. The composition and surface structure of the sensor were carefully characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and various electrochemical techniques. Such interlaced network architectures, providing better mass transport and allowing more AChE loading per unit area, as well as the intrinsically strong visible light-harvesting effect from BiOI, greatly facilitate the PEC responses. On the basis of the effect of OPs on the photocurrent of AChE–BiOINFs/ITO, a highly sensitive visible light-activated photoelectrochemical biosensor was developed for biosensing OPs. The conditions for OPs detection were optimized by using methyl parathion (MP) as a model OP compound. Under the optimized experimental conditions, our results show that such a newly designed AChE–BiOINFs/ITO photoactive electrode provides remarkably improved sensitivity and selectivity for the biosensing of OPs. The detection limit was found to be as low as about 0.04ngmL−1 (S/N=3). Toward the goal for practical applications, the resulting sensor was further evaluated by monitoring MP in spiked vegetable samples, showing fine applicability for the detection of MP in real samples.
Source:Biosensors and Bioelectronics, Volume 38, Issue 1
Jingming Gong, Xiaoqing Wang, Xue Li, Kewei Wang
A new, highly sensitive and selective biosensor for the photoelectrochemical (PEC) detection of organophosphate pesticides (OPs) has been developed, whereby newly synthesized crossed bismuth oxyiodide (BiOI) nanoflake arrays (BiOINFs) are fabricated as a photoactive electrode via a successive ionic layer adsorption and reaction (SILAR) approach. The smart integration of BiOINFs with biomolecules acetylcholinesterase (AChE) yields a novel AChE–BiOINFs hybrid, constructing a three-dimensional (3D) porous network biosensing platform. The composition and surface structure of the sensor were carefully characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and various electrochemical techniques. Such interlaced network architectures, providing better mass transport and allowing more AChE loading per unit area, as well as the intrinsically strong visible light-harvesting effect from BiOI, greatly facilitate the PEC responses. On the basis of the effect of OPs on the photocurrent of AChE–BiOINFs/ITO, a highly sensitive visible light-activated photoelectrochemical biosensor was developed for biosensing OPs. The conditions for OPs detection were optimized by using methyl parathion (MP) as a model OP compound. Under the optimized experimental conditions, our results show that such a newly designed AChE–BiOINFs/ITO photoactive electrode provides remarkably improved sensitivity and selectivity for the biosensing of OPs. The detection limit was found to be as low as about 0.04ngmL−1 (S/N=3). Toward the goal for practical applications, the resulting sensor was further evaluated by monitoring MP in spiked vegetable samples, showing fine applicability for the detection of MP in real samples.
Highlights
► Newly synthesized crossed BiOI nanoflake arrays fabricated as a photoactive electrode. ► The first smart integration of BiOINFs with acetylcholinesterase. ► A highly sensitive and selective biosensor for PEC detection of OPs developed.In situ enzymatic silver enhancement based on functionalized graphene oxide and layer-by-layer assembled gold nanoparticles for ultrasensitive detection of thrombin
01 August 2012,
10:42:44
Publication year:
2012
Source:Biosensors and Bioelectronics, Volume 38, Issue 1
Yan Wang, Ruo Yuan, Yaqin Chai, Yali Yuan, Lijuan Bai
A highly specific in situ amplification strategy was designed for ultrasensitive detection of thrombin by combining the layer-by-layer (LBL) assembled amplification with alkaline phosphatase (ALP) and gold nanoparticles (Au) mediated silver deposition. High-density carboxyl functionalized graphene oxide (FGO) was introduced as a nanocarrier for LBL assembling of alkaline phosphatase decorated gold nanoparticles (ALP-Au), which was further adopted to label thrombin aptamer II. After sandwich-type reaction, numerous ALP were captured onto the aptasensor surface and catalyzed the hydrolysis of ascorbic acid 2-phosphate (AAP), which in situ generated ascorbic acid (AA), reducing Ag+ to Ag nanoparticles (AgNPs) for electrochemical readout. Inspiringly, the in situ amplification strategy with ethanolamine as an effective blocking agent showed remarkable amplification efficiency, very little nonspecific adsorption, and low background signal, which was favorable to enhance the sensitivity of aptasensor. Our novel dramatic signal amplification strategy, with a detection limit of 2.7fM, showed about 2–3 orders of magnitude improvement in the sensitivity for thrombin detection compared to other universal enzyme-based electrochemical assay.
Source:Biosensors and Bioelectronics, Volume 38, Issue 1
Yan Wang, Ruo Yuan, Yaqin Chai, Yali Yuan, Lijuan Bai
A highly specific in situ amplification strategy was designed for ultrasensitive detection of thrombin by combining the layer-by-layer (LBL) assembled amplification with alkaline phosphatase (ALP) and gold nanoparticles (Au) mediated silver deposition. High-density carboxyl functionalized graphene oxide (FGO) was introduced as a nanocarrier for LBL assembling of alkaline phosphatase decorated gold nanoparticles (ALP-Au), which was further adopted to label thrombin aptamer II. After sandwich-type reaction, numerous ALP were captured onto the aptasensor surface and catalyzed the hydrolysis of ascorbic acid 2-phosphate (AAP), which in situ generated ascorbic acid (AA), reducing Ag+ to Ag nanoparticles (AgNPs) for electrochemical readout. Inspiringly, the in situ amplification strategy with ethanolamine as an effective blocking agent showed remarkable amplification efficiency, very little nonspecific adsorption, and low background signal, which was favorable to enhance the sensitivity of aptasensor. Our novel dramatic signal amplification strategy, with a detection limit of 2.7fM, showed about 2–3 orders of magnitude improvement in the sensitivity for thrombin detection compared to other universal enzyme-based electrochemical assay.
Highlights
► A highly specific one-step in situ silver signal-transduction label was designed for ultrasensitive electrochemical detection of thrombin by combining the layer-by-layer (LBL) assembled amplification with in situ enzyme-induced silver deposition. ► The selected KCl detection solution provided a well-defined symmetrically sharp silver stripping peak, which potentially paved sensitive way for electrochemical readout. ► With ethanolamine as an effective blocking agent, the aptasensor gave a low background signal, assisting to push down the detection limit.Efficient one-pot synthesis of molecularly imprinted silica nanospheres embedded carbon dots for fluorescent dopamine optosensing
01 August 2012,
10:42:44
Publication year:
2012
Source:Biosensors and Bioelectronics, Volume 38, Issue 1
Yan Mao, Yu Bao, Dongxue Han, Fenghua Li, Li Niu
A new type of eco-friendly molecularly imprinted polymer (MIP) was synthesized through an efficient one-pot room-temperature sol–gel polymerization and applied as a molecular recognition element to construct dopamine (DA) fluorescence (FL) optosensor. Highly luminescent carbon dots (CDs) were firstly synthesized via a one-step reaction in organosilane, and their surface were anchored with MIP matrix (CDs@MIP). The resulting composite of a synergetic combination of CDs with MIP showed high photostability and template selectivity. Moreover, the composite allowed a highly sensitive determination of DA via FL intensity decreasing when removal of the original templates. The new MIP-based DA sensing protocol was applied to detect DA concentration in aqueous solution, the relative FL intensity of CDs@MIP decreased linearly with the increasing DA in the concentration range of 25–500nM with a detection limit (3σ) of 1.7nM. Furthermore, the proposed method was successfully intended for the determination of trace DA in human urine samples without the interference of other molecules and ions.
Source:Biosensors and Bioelectronics, Volume 38, Issue 1
Yan Mao, Yu Bao, Dongxue Han, Fenghua Li, Li Niu
A new type of eco-friendly molecularly imprinted polymer (MIP) was synthesized through an efficient one-pot room-temperature sol–gel polymerization and applied as a molecular recognition element to construct dopamine (DA) fluorescence (FL) optosensor. Highly luminescent carbon dots (CDs) were firstly synthesized via a one-step reaction in organosilane, and their surface were anchored with MIP matrix (CDs@MIP). The resulting composite of a synergetic combination of CDs with MIP showed high photostability and template selectivity. Moreover, the composite allowed a highly sensitive determination of DA via FL intensity decreasing when removal of the original templates. The new MIP-based DA sensing protocol was applied to detect DA concentration in aqueous solution, the relative FL intensity of CDs@MIP decreased linearly with the increasing DA in the concentration range of 25–500nM with a detection limit (3σ) of 1.7nM. Furthermore, the proposed method was successfully intended for the determination of trace DA in human urine samples without the interference of other molecules and ions.
Highlights
► An eco-friendly CDs@MIP composite was synthesized. ► The synthesis process was a one-pot room-temperature sol–gel polymerization. ► CDs@MIP was the molecular recognition element of fluorescence optosensor. ► The optosensor exhibited high sensitive and selective towards dopamine.Electrochemical DNA biosensor for bovine papillomavirus detection using polymeric film on screen-printed electrode
01 August 2012,
10:42:44
Publication year:
2012
Source:Biosensors and Bioelectronics, Volume 38, Issue 1
Gustavo A. Nascimento, Elaine V.M. Souza, Danielly S. Campos-Ferreira, Mariana S. Arruda, Carlos H.M. Castelletti, Marcela S.O. Wanderley, Marek H.F. Ekert, Danyelly Bruneska, José L. Lima-Filho
A new electrochemical DNA biosensor for bovine papillomavirus (BPV) detection that was based on screen-printed electrodes was comprehensively studied by electrochemical methods of cyclic voltammetry (CV) and differential pulse voltammetry (DPV). A BPV probe was immobilised on a working electrode (gold) modified with a polymeric film of poly-L-lysine (PLL) and chitosan. The experimental design was carried out to evaluate the influence of polymers, probe concentration (BPV probe) and immobilisation time on the electrochemical reduction of methylene blue (MB). The polymer poly-L-lysine (PLL), a probe concentration of 1μM and an immobilisation time of 60min showed the best result for the BPV probe immobilisation. With the hybridisation of a complementary target sequence (BPV target), the electrochemical signal decreased compared to a BPV probe immobilised on the modified PLL-gold electrode. Viral DNA that was extracted from cattle with papillomatosis also showed a decrease in the MB electrochemical reduction, which suggested that the decreased electrochemical signal corresponded to a bovine papillomavirus infection. The hybridisation specificity experiments further indicated that the biosensor could discriminate the complementary sequence from the non-complementary sequence. Thus, the results showed that the development of analytical devices, such as a biosensor, could assist in the rapid and efficient detection of bovine papillomavirus DNA and help in the prevention and treatment of papillomatosis in cattle.
Source:Biosensors and Bioelectronics, Volume 38, Issue 1
Gustavo A. Nascimento, Elaine V.M. Souza, Danielly S. Campos-Ferreira, Mariana S. Arruda, Carlos H.M. Castelletti, Marcela S.O. Wanderley, Marek H.F. Ekert, Danyelly Bruneska, José L. Lima-Filho
A new electrochemical DNA biosensor for bovine papillomavirus (BPV) detection that was based on screen-printed electrodes was comprehensively studied by electrochemical methods of cyclic voltammetry (CV) and differential pulse voltammetry (DPV). A BPV probe was immobilised on a working electrode (gold) modified with a polymeric film of poly-L-lysine (PLL) and chitosan. The experimental design was carried out to evaluate the influence of polymers, probe concentration (BPV probe) and immobilisation time on the electrochemical reduction of methylene blue (MB). The polymer poly-L-lysine (PLL), a probe concentration of 1μM and an immobilisation time of 60min showed the best result for the BPV probe immobilisation. With the hybridisation of a complementary target sequence (BPV target), the electrochemical signal decreased compared to a BPV probe immobilised on the modified PLL-gold electrode. Viral DNA that was extracted from cattle with papillomatosis also showed a decrease in the MB electrochemical reduction, which suggested that the decreased electrochemical signal corresponded to a bovine papillomavirus infection. The hybridisation specificity experiments further indicated that the biosensor could discriminate the complementary sequence from the non-complementary sequence. Thus, the results showed that the development of analytical devices, such as a biosensor, could assist in the rapid and efficient detection of bovine papillomavirus DNA and help in the prevention and treatment of papillomatosis in cattle.
Highlights
► Electrochemical DNA sensor used to detect bovine papillomavirus. ► Polymeric film from poly-L-lysine (PLL) and chitosan was formed on gold electrode. ► Methylene blue (MB) electrochemical reduction decreased when the hybridisation occurred. ► The extracted Viral DNA from cattle with papillomatosis also decreased electrochemical signal. ► The detection limit was 4.35nM in the range from 5nM to 100nM.Rapid detection of avian influenza H5N1 virus using impedance measurement of immuno-reaction coupled with RBC amplification
01 August 2012,
10:42:44
Publication year:
2012
Source:Biosensors and Bioelectronics, Volume 38, Issue 1
Jacob Lum, Ronghui Wang, Kentu Lassiter, Balaji Srinivasan, Daad Abi-Ghanem, Luc Berghman, Billy Hargis, Steve Tung, Huaguang Lu, Yanbin Li
Avian influenza virus (AIV) subtype H5N1 was first discovered in the 1990s and since then its emergence has become a likely source of a global pandemic and economic loss. Currently accepted gold standard methods of influenza detection, viral culture and rRT-PCR, are time consuming, expensive and require special training and laboratory facilities. A rapid, sensitive, and specific screening method is needed for in-field or bedside testing of AI virus to effectively implement quarantines and medications. Therefore, the objective of this study was to improve the specificity and sensitivity of an impedance biosensor that has been developed for the screening of AIV H5. Three major components of the developed biosensor are immunomagnetic nanoparticles for the separation of AI virus, a microfluidic chip for sample control and an interdigitated microelectrode for impedance measurement. In this study polyclonal antibody against N1 subtype was immobilized on the surface of the microelectrode to specifically bind AIV H5N1 to generate more specific impedance signal and chicken red blood cells (RBC) were used as biolabels to attach to AIV H5N1 captured on the microelectrode to amplify impedance signal. RBC amplification was shown to increase the impedance signal change by more than 100% compared to the protocol without RBC biolabels, and was necessary for forming a linear calibration curve for the biosensor. The use of a second antibody against N1 offered much greater specificity and reliability than the previous biosensor protocol. The biosensor was able to detect AIV H5N1 at concentrations down to 103 EID50 ml−1 in less than 2h.
Source:Biosensors and Bioelectronics, Volume 38, Issue 1
Jacob Lum, Ronghui Wang, Kentu Lassiter, Balaji Srinivasan, Daad Abi-Ghanem, Luc Berghman, Billy Hargis, Steve Tung, Huaguang Lu, Yanbin Li
Avian influenza virus (AIV) subtype H5N1 was first discovered in the 1990s and since then its emergence has become a likely source of a global pandemic and economic loss. Currently accepted gold standard methods of influenza detection, viral culture and rRT-PCR, are time consuming, expensive and require special training and laboratory facilities. A rapid, sensitive, and specific screening method is needed for in-field or bedside testing of AI virus to effectively implement quarantines and medications. Therefore, the objective of this study was to improve the specificity and sensitivity of an impedance biosensor that has been developed for the screening of AIV H5. Three major components of the developed biosensor are immunomagnetic nanoparticles for the separation of AI virus, a microfluidic chip for sample control and an interdigitated microelectrode for impedance measurement. In this study polyclonal antibody against N1 subtype was immobilized on the surface of the microelectrode to specifically bind AIV H5N1 to generate more specific impedance signal and chicken red blood cells (RBC) were used as biolabels to attach to AIV H5N1 captured on the microelectrode to amplify impedance signal. RBC amplification was shown to increase the impedance signal change by more than 100% compared to the protocol without RBC biolabels, and was necessary for forming a linear calibration curve for the biosensor. The use of a second antibody against N1 offered much greater specificity and reliability than the previous biosensor protocol. The biosensor was able to detect AIV H5N1 at concentrations down to 103 EID50 ml−1 in less than 2h.
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