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papers from the latest issue:
Synthesis of surface molecularly imprinted nanoparticles for recognition of lysozyme using a metal coordination monomer
03 November 2013,
19:39:14
Publication date: 15 March
2014
Source:Biosensors and Bioelectronics, Volume 53
Author(s): Huachang Chen , Juan Kong , Dongying Yuan , Guoqi Fu
Molecularly imprinted polymers against proteins are regarded as promising substitutes for natural antibodies, but have been frustrated with the problems including reduced interaction between functional monomers and protein template in the aqueous media required during their synthesis and restricted mass transfer across the resulting crosslinked polymer matrixes. For addressing these issues, herein we proposed a strategy for imprinting of a protein on the surface of nanoparticles using a metal chelating monomer. With lysozyme as a model protein template and Cu2+ chelating N-(4-vinyl)-benzyl iminodiacetic acid as the coordination monomer along with other monomers, protein imprinted polymer nanoshells were formed over vinyl-modified silica nanoparticles via surface polymerization in high-dilution monomer solution. The feed concentration of the crosslinking monomer was optimized toward achieving the best imprinting effect. Compared with the related imprinted materials reported previously, the resultant core–shell imprinted particles showed greatly faster binding kinetics, elevated rebinding capacity and selectivity. More importantly, noticeably high binding affinity was achieved with an estimated dissociation constant of 4.1×10−8 M which is comparable to that of conventional antibodies
Source:Biosensors and Bioelectronics, Volume 53
Author(s): Huachang Chen , Juan Kong , Dongying Yuan , Guoqi Fu
Molecularly imprinted polymers against proteins are regarded as promising substitutes for natural antibodies, but have been frustrated with the problems including reduced interaction between functional monomers and protein template in the aqueous media required during their synthesis and restricted mass transfer across the resulting crosslinked polymer matrixes. For addressing these issues, herein we proposed a strategy for imprinting of a protein on the surface of nanoparticles using a metal chelating monomer. With lysozyme as a model protein template and Cu2+ chelating N-(4-vinyl)-benzyl iminodiacetic acid as the coordination monomer along with other monomers, protein imprinted polymer nanoshells were formed over vinyl-modified silica nanoparticles via surface polymerization in high-dilution monomer solution. The feed concentration of the crosslinking monomer was optimized toward achieving the best imprinting effect. Compared with the related imprinted materials reported previously, the resultant core–shell imprinted particles showed greatly faster binding kinetics, elevated rebinding capacity and selectivity. More importantly, noticeably high binding affinity was achieved with an estimated dissociation constant of 4.1×10−8 M which is comparable to that of conventional antibodies
Label-free electrochemical biosensor using home-made 10-methyl-3-nitro-acridone as indicator for picomolar detection of nuclear factor kappa B
03 November 2013,
19:39:14
Publication date: 15 March
2014
Source:Biosensors and Bioelectronics, Volume 53
Author(s): Jing Hua Chen , Xi Zhang , Shuxian Cai , Dongzhi Wu , Jia Lin , Chunyan Li , Jing Zhang
A new acridone derivative 10-methyl-3-nitro-acridone (MNA) with excellent electrochemical activity was synthesized in this paper. Using it as an electrochemical indicator, a signal-on and label-free electrochemical biosensor was developed for picomolar determination of nuclear factor kappa B (NF-κB) in serum. Initially, linear double-stranded DNA (dsDNA) probes, which contain a protein-binding site specific to NF-κB, were self-assembled on the surface of a glass carbon electrode (GCE). If the NF-κB was absent, the dsDNA probes were cut into ss-DNA fragments by the digestion of ExoIII, resulting in a low electrochemical signal of MNA due to the weak binding affinity of MNA to ss-DNA. On the contrary, in the presence of NF-κB, it could bind with the dsDNA probes at the specific site and hinder the digestion of ExoIII, resulting in a significant increase of electrochemical response due to the intercalation of MNA into the dsDNA probes. By employing the above strategy, this sensor could detect as low as 40pM NF-κB with high specificity. To the best of our knowledge, the proposed sensor is the first attempt to use acridone derivative as an electrochemical indicator for NF-κB detection, which may represent a promising path toward clinical diagnosis and drug developments.
Source:Biosensors and Bioelectronics, Volume 53
Author(s): Jing Hua Chen , Xi Zhang , Shuxian Cai , Dongzhi Wu , Jia Lin , Chunyan Li , Jing Zhang
A new acridone derivative 10-methyl-3-nitro-acridone (MNA) with excellent electrochemical activity was synthesized in this paper. Using it as an electrochemical indicator, a signal-on and label-free electrochemical biosensor was developed for picomolar determination of nuclear factor kappa B (NF-κB) in serum. Initially, linear double-stranded DNA (dsDNA) probes, which contain a protein-binding site specific to NF-κB, were self-assembled on the surface of a glass carbon electrode (GCE). If the NF-κB was absent, the dsDNA probes were cut into ss-DNA fragments by the digestion of ExoIII, resulting in a low electrochemical signal of MNA due to the weak binding affinity of MNA to ss-DNA. On the contrary, in the presence of NF-κB, it could bind with the dsDNA probes at the specific site and hinder the digestion of ExoIII, resulting in a significant increase of electrochemical response due to the intercalation of MNA into the dsDNA probes. By employing the above strategy, this sensor could detect as low as 40pM NF-κB with high specificity. To the best of our knowledge, the proposed sensor is the first attempt to use acridone derivative as an electrochemical indicator for NF-κB detection, which may represent a promising path toward clinical diagnosis and drug developments.
Cell-based high-throughput odorant screening system through visualization on a microwell array
03 November 2013,
19:39:14
Publication date: 15 March
2014
Source:Biosensors and Bioelectronics, Volume 53
Author(s): Eun Hae Oh , Seung Hwan Lee , Sang Hun Lee , Hwi Jin Ko , Tai Hyun Park
The development of a cell-based high-throughput screening system has attracted much attention from researchers who study drug screening mechanisms and characterization of G-protein coupled receptors (GPCRs). Although olfactory receptors (ORs) constitute the largest group of GPCRs that play a critical role recognizing and discriminating odorants, only a few ORs have been characterized, and most remain orphan. The conventional cell-based assay system for characterizing GPCRs, including ORs, is very laborious, time consuming, and requires an expensive assay system. In this study, we developed a simple, low-cost miniaturized odorant screening method by combining Micro-Electro-Mechanical system (MEMs) technique and visualization technique for detecting an odorant response. We fabricated PEG microwell from a photocrosslinkable polyethylene glycol diacrylate (PEGDA) solution and applied it to cell culture and a reverse transfection platform for cell-based high-throughput screening. For the first time, the olfactory receptors were expressed on the microwell platform using reverse transfection technique. The various olfactory receptors can be expressed simultaneously using this technique and the microwell spotted with olfactory receptor genes can be used as a high-throughput screening platform. The odorant response was detected via fluorescence analysis on the microwell using a cAMP response element (CRE) reporter assay. We tested this platform using four de-orphaned ORs. This new cell-based screening method not only reduced numerous time-consuming steps but also allowed for simple, efficient, and quantitative screening and patterning of large numbers of GPCRs including ORs, which can help to visualize the OR response to odorants on a microwell.
Source:Biosensors and Bioelectronics, Volume 53
Author(s): Eun Hae Oh , Seung Hwan Lee , Sang Hun Lee , Hwi Jin Ko , Tai Hyun Park
The development of a cell-based high-throughput screening system has attracted much attention from researchers who study drug screening mechanisms and characterization of G-protein coupled receptors (GPCRs). Although olfactory receptors (ORs) constitute the largest group of GPCRs that play a critical role recognizing and discriminating odorants, only a few ORs have been characterized, and most remain orphan. The conventional cell-based assay system for characterizing GPCRs, including ORs, is very laborious, time consuming, and requires an expensive assay system. In this study, we developed a simple, low-cost miniaturized odorant screening method by combining Micro-Electro-Mechanical system (MEMs) technique and visualization technique for detecting an odorant response. We fabricated PEG microwell from a photocrosslinkable polyethylene glycol diacrylate (PEGDA) solution and applied it to cell culture and a reverse transfection platform for cell-based high-throughput screening. For the first time, the olfactory receptors were expressed on the microwell platform using reverse transfection technique. The various olfactory receptors can be expressed simultaneously using this technique and the microwell spotted with olfactory receptor genes can be used as a high-throughput screening platform. The odorant response was detected via fluorescence analysis on the microwell using a cAMP response element (CRE) reporter assay. We tested this platform using four de-orphaned ORs. This new cell-based screening method not only reduced numerous time-consuming steps but also allowed for simple, efficient, and quantitative screening and patterning of large numbers of GPCRs including ORs, which can help to visualize the OR response to odorants on a microwell.
Lipase-nanoporous gold biocomposite modified electrode for reliable detection of triglycerides
03 November 2013,
19:39:14
Publication date: 15 March
2014
Source:Biosensors and Bioelectronics, Volume 53
Author(s): Chao Wu , Xueying Liu , Yufei Li , Xiaoyu Du , Xia Wang , Ping Xu
For triglycerides biosensor design, protein immobilization is necessary to create the interface between the enzyme and the electrode. In this study, a glassy carbon electrode (GCE) was modified with lipase-nanoporous gold (NPG) biocomposite (denoted as lipase/NPG/GCE). Due to highly conductive, porous, and biocompatible three-dimensional structure, NPG is suitable for enzyme immobilization. In cyclic voltammetry experiments, the lipase/NPG/GCE bioelectrode displayed surface-confined reaction in a phosphate buffer solution. Linear responses were obtained for tributyrin concentrations ranging from 50 to 250mgdl−1 and olive oil concentrations ranging from 10 to 200mgdl−1. The value of apparent Michaelis–Menten constant for tributyrin was 10.67mgdl−1 and the detection limit was 2.68mgdl−1. Further, the lipase/NPG/GCE bioelectrode had strong anti-interference ability against urea, glucose, cholesterol, and uric acid as well as a long shelf-life. For the detection of triglycerides in human serum, the values given by the lipase/NPG/GCE bioelectrode were in good agreement with those of an automatic biochemical analyzer. These properties along with a long self-life make the lipase/NPG/GCE bioelectrode an excellent choice for the construction of triglycerides biosensor.
Source:Biosensors and Bioelectronics, Volume 53
Author(s): Chao Wu , Xueying Liu , Yufei Li , Xiaoyu Du , Xia Wang , Ping Xu
For triglycerides biosensor design, protein immobilization is necessary to create the interface between the enzyme and the electrode. In this study, a glassy carbon electrode (GCE) was modified with lipase-nanoporous gold (NPG) biocomposite (denoted as lipase/NPG/GCE). Due to highly conductive, porous, and biocompatible three-dimensional structure, NPG is suitable for enzyme immobilization. In cyclic voltammetry experiments, the lipase/NPG/GCE bioelectrode displayed surface-confined reaction in a phosphate buffer solution. Linear responses were obtained for tributyrin concentrations ranging from 50 to 250mgdl−1 and olive oil concentrations ranging from 10 to 200mgdl−1. The value of apparent Michaelis–Menten constant for tributyrin was 10.67mgdl−1 and the detection limit was 2.68mgdl−1. Further, the lipase/NPG/GCE bioelectrode had strong anti-interference ability against urea, glucose, cholesterol, and uric acid as well as a long shelf-life. For the detection of triglycerides in human serum, the values given by the lipase/NPG/GCE bioelectrode were in good agreement with those of an automatic biochemical analyzer. These properties along with a long self-life make the lipase/NPG/GCE bioelectrode an excellent choice for the construction of triglycerides biosensor.
Black silicon SERS substrate: Effect of surface morphology on SERS detection and application of single algal cell analysis
03 November 2013,
19:39:14
Publication date: 15 March
2014
Source:Biosensors and Bioelectronics, Volume 53
Author(s): Yu-Luen Deng , Yi-Je Juang
In this study, we have investigated the effect of the surface morphology of the black silicon substrate on surface enhanced Raman spectroscopy (SERS) and explored its application of single algal cell detection. By adjusting the O2 and SF6 flow rates in the cryogenic plasma etching process, different surface morphologies of the black silicon substrate was produced without performing the lithographic process. It was found the Raman signals were better enhanced as the tip density of the black silicon substrate increased. In addition, as the thickness of the deposited gold layer increased, the SERS effect increased as well, which could be owing to the generation of more hot spots by bridging individual silicon tips through deposition of gold layer. For the black silicon substrate with tip density of 30tips/μm2 and covered by 400nm deposited gold layer, the detection limit of 10fM R6G solution concentration with uniform SERS effect across the substrate was achieved. Furthermore, detection of individual algal cell (Chlorella vulgaris) was performed at the SERS substrate as fabricated and the Raman signals of carotenoid and lipid were substantially enhanced.
Source:Biosensors and Bioelectronics, Volume 53
Author(s): Yu-Luen Deng , Yi-Je Juang
In this study, we have investigated the effect of the surface morphology of the black silicon substrate on surface enhanced Raman spectroscopy (SERS) and explored its application of single algal cell detection. By adjusting the O2 and SF6 flow rates in the cryogenic plasma etching process, different surface morphologies of the black silicon substrate was produced without performing the lithographic process. It was found the Raman signals were better enhanced as the tip density of the black silicon substrate increased. In addition, as the thickness of the deposited gold layer increased, the SERS effect increased as well, which could be owing to the generation of more hot spots by bridging individual silicon tips through deposition of gold layer. For the black silicon substrate with tip density of 30tips/μm2 and covered by 400nm deposited gold layer, the detection limit of 10fM R6G solution concentration with uniform SERS effect across the substrate was achieved. Furthermore, detection of individual algal cell (Chlorella vulgaris) was performed at the SERS substrate as fabricated and the Raman signals of carotenoid and lipid were substantially enhanced.
Assessment of genotoxicity of catecholics using impedimetric DNA-biosensor
03 November 2013,
19:39:14
Publication date: 15 March
2014
Source:Biosensors and Bioelectronics, Volume 53
Author(s): Ali A. Ensafi , Maryam Amini , B. Rezaei
The potential toxicity of catecholics is a big concern, because the catechol-derived semiquinone radical after the oxidation of catechol (CA) can donate an H-atom to generate quinone, and during this process a superoxide anion radical may be produced. Considering the fact that catecholics are highly consumed in our daily life and some drugs also contain one or more CA moieties, we speculate that CA's toxicity might not be insurmountable. Therefore, finding approaches to investigate catecholics potential toxicity is of great significance. Here in, an electrochemical protocol for direct monitoring of genotoxicity of catecholics is described. CA encapsulated on MWCNTs (CA@MWCNT) through continuous cyclic voltammetric on the surface of pencil graphite electrode (PGE). Subsequently, a DNA functionalized biosensor (DNA/CA@MWCNT/PGE) was prepared and characterized for the detection and the investigation of DNA damage induced by radicals generated from catecholics. The change in the charge transfer resistance (R ct ) after the incubation of the DNA biosensor in the damaging solution for a certain time was used as an indicator for DNA damage. Incubation of DNA-modified electrode with CA solution containing Cu(II), Cr(VI) and Fe(III) has been shown to result in oxidative damage to the DNA and change in the electrochemical properties. It was found that the presence of Cu(II), Cr(VI) and Fe(III) in solution caused damage to DNA. The inhibitory effect of glutathione and plumbagin on the CA-mediated DNA damage has also been investigated using the biosensor. The minimum concentration of the metal ions for CA induced DNA damage was investigated. Recognition of suitable matrixes for CA-mediated DNA damage can be assessed using proposed DNA biosensor. Such direct monitoring of the DNA damage holds great promise for designing new biosensors with modification of the biosensor with different damaging agents.
Source:Biosensors and Bioelectronics, Volume 53
Author(s): Ali A. Ensafi , Maryam Amini , B. Rezaei
The potential toxicity of catecholics is a big concern, because the catechol-derived semiquinone radical after the oxidation of catechol (CA) can donate an H-atom to generate quinone, and during this process a superoxide anion radical may be produced. Considering the fact that catecholics are highly consumed in our daily life and some drugs also contain one or more CA moieties, we speculate that CA's toxicity might not be insurmountable. Therefore, finding approaches to investigate catecholics potential toxicity is of great significance. Here in, an electrochemical protocol for direct monitoring of genotoxicity of catecholics is described. CA encapsulated on MWCNTs (CA@MWCNT) through continuous cyclic voltammetric on the surface of pencil graphite electrode (PGE). Subsequently, a DNA functionalized biosensor (DNA/CA@MWCNT/PGE) was prepared and characterized for the detection and the investigation of DNA damage induced by radicals generated from catecholics. The change in the charge transfer resistance (R ct ) after the incubation of the DNA biosensor in the damaging solution for a certain time was used as an indicator for DNA damage. Incubation of DNA-modified electrode with CA solution containing Cu(II), Cr(VI) and Fe(III) has been shown to result in oxidative damage to the DNA and change in the electrochemical properties. It was found that the presence of Cu(II), Cr(VI) and Fe(III) in solution caused damage to DNA. The inhibitory effect of glutathione and plumbagin on the CA-mediated DNA damage has also been investigated using the biosensor. The minimum concentration of the metal ions for CA induced DNA damage was investigated. Recognition of suitable matrixes for CA-mediated DNA damage can be assessed using proposed DNA biosensor. Such direct monitoring of the DNA damage holds great promise for designing new biosensors with modification of the biosensor with different damaging agents.
Polymers effects on synthesis of AuNPs, and Au/Ag nanoalloys: Indirectly generated AuNPs and versatile sensing applications including anti-leukemic agent
03 November 2013,
19:39:14
Publication date: 15 March
2014
Source:Biosensors and Bioelectronics, Volume 53
Author(s): Shanaz Jahan , Farrukh Mansoor , Shamsa Kanwal
Polymers either serve as shielding or capping agents to restrict the nanoparticle size. This study demonstrates the polymer depositions and their effects in synthesis and sharp stabilization of gold nanoparticles (AuNPs) and to develop gold/silver nanoalloys (Au/Ag nanoalloys). Effects of different polymers are tested to justify their role in synthesis and stability of phloroglucinol (PG) coated AuNPs and Au/Ag nanoalloys. Cationic and anionic i.e. [Polydiallyldimethylammonium]+ (PDDA), [Polyethyleneimine]+ (PEI), [Polystyrene sulfonate]2− (PSS) and neutral polymer Polychlorotriflouroethylene (PCTFE) produce praiseworthy stable AuNPs and Au/Ag nanoalloy. To prove polymer effects characterization protocols including UV–vis, Fluorescence (PL), IR and AFM imaging are performed to fully investigate the mechanism and size characteristics of these nanoparticles/nanoalloys. In this study sharp size controlling/sheilding effects were observed particularly with cationic polymers simply through the favorable electrostatic interactions with the terminal ends of PG Potent/significant detection of doxorubicin (DOX, an antileukemic agent) via fluorescence resonance energy transfer (FRET) between PEI shielded AuNPs (AuNPEI) and DOX was achieved upto 10pM level, while PDDA protected AuNPs facilitated the detection of ascorbic acid based on fluorescence enhancement effects in wide range (10–200nM) and with detection limit of 200pM. Similarly sensing performance of PEI stabilized Au/Ag nanoalloys on addition of halides (Cl−, Br-, I−) is evaluated through red shifted SPR along with continuous increase in absorbance and also through AFM. Moreover the addition of halide ions also helped the regeneration of AuNPs by taking away silver from the Au/Ag nanoalloys enabling their detections upto subnanomolar levels.
Source:Biosensors and Bioelectronics, Volume 53
Author(s): Shanaz Jahan , Farrukh Mansoor , Shamsa Kanwal
Polymers either serve as shielding or capping agents to restrict the nanoparticle size. This study demonstrates the polymer depositions and their effects in synthesis and sharp stabilization of gold nanoparticles (AuNPs) and to develop gold/silver nanoalloys (Au/Ag nanoalloys). Effects of different polymers are tested to justify their role in synthesis and stability of phloroglucinol (PG) coated AuNPs and Au/Ag nanoalloys. Cationic and anionic i.e. [Polydiallyldimethylammonium]+ (PDDA), [Polyethyleneimine]+ (PEI), [Polystyrene sulfonate]2− (PSS) and neutral polymer Polychlorotriflouroethylene (PCTFE) produce praiseworthy stable AuNPs and Au/Ag nanoalloy. To prove polymer effects characterization protocols including UV–vis, Fluorescence (PL), IR and AFM imaging are performed to fully investigate the mechanism and size characteristics of these nanoparticles/nanoalloys. In this study sharp size controlling/sheilding effects were observed particularly with cationic polymers simply through the favorable electrostatic interactions with the terminal ends of PG Potent/significant detection of doxorubicin (DOX, an antileukemic agent) via fluorescence resonance energy transfer (FRET) between PEI shielded AuNPs (AuNPEI) and DOX was achieved upto 10pM level, while PDDA protected AuNPs facilitated the detection of ascorbic acid based on fluorescence enhancement effects in wide range (10–200nM) and with detection limit of 200pM. Similarly sensing performance of PEI stabilized Au/Ag nanoalloys on addition of halides (Cl−, Br-, I−) is evaluated through red shifted SPR along with continuous increase in absorbance and also through AFM. Moreover the addition of halide ions also helped the regeneration of AuNPs by taking away silver from the Au/Ag nanoalloys enabling their detections upto subnanomolar levels.
An aptamer based wall-less LSPR array chip for label-free and high throughput detection of biomolecules
03 November 2013,
19:39:14
Publication date: 15 March
2014
Source:Biosensors and Bioelectronics, Volume 53
Author(s): Liping Xie , Xiaojun Yan , Yanan Du
Despite recent progress in localized surface plasmon resonance (LSPR) based bio-sensing, it remains challenging to achieve sensitive and high throughput LSPR detection with facilities available in common laboratories. Here we developed a wall-less LSPR array chip for facile, label-free and high throughput detection of biomolecules using a normal microplate reader. The wall-less LSPR array chip was fabricated by immobilizing plasmonic nanoparticles (NPs) on a hydrophilic–hydrophobic patterned glass slide, enabling high throughput detection. The wall-less configuration simplifies chip fabrication and sample processing, and enables miniaturization to significantly reduce sample and reagent consumption. A double-gold NPs enhanced system comprising of 13-nm-gold NPs conjugated to aptamer modified 39-nm-gold NPs on glass substrate was adopted to constitute competitive replacement assay for signal amplification in small molecule (i.e. ATP) detection. Upon enhancement, the detection sensitivity of ATP was augmented by 5 orders of magnitude from 0.01µM to 100µM measured by the laboratory microplate reader. The wall-less LSPR sensor chip can be widely applied for miniaturized and high throughput detection of a variety of targets in biomedical applications and environmental monitoring using facilities available in common laboratories.
Source:Biosensors and Bioelectronics, Volume 53
Author(s): Liping Xie , Xiaojun Yan , Yanan Du
Despite recent progress in localized surface plasmon resonance (LSPR) based bio-sensing, it remains challenging to achieve sensitive and high throughput LSPR detection with facilities available in common laboratories. Here we developed a wall-less LSPR array chip for facile, label-free and high throughput detection of biomolecules using a normal microplate reader. The wall-less LSPR array chip was fabricated by immobilizing plasmonic nanoparticles (NPs) on a hydrophilic–hydrophobic patterned glass slide, enabling high throughput detection. The wall-less configuration simplifies chip fabrication and sample processing, and enables miniaturization to significantly reduce sample and reagent consumption. A double-gold NPs enhanced system comprising of 13-nm-gold NPs conjugated to aptamer modified 39-nm-gold NPs on glass substrate was adopted to constitute competitive replacement assay for signal amplification in small molecule (i.e. ATP) detection. Upon enhancement, the detection sensitivity of ATP was augmented by 5 orders of magnitude from 0.01µM to 100µM measured by the laboratory microplate reader. The wall-less LSPR sensor chip can be widely applied for miniaturized and high throughput detection of a variety of targets in biomedical applications and environmental monitoring using facilities available in common laboratories.
Graphical abstract
Hi, My partner and I are doing a project for our high school chemistry class. It is on polymers and we had chosen to do it on bio-sensors. We have been scanning through websites like crazy and can not seem to find what we need. So we thought why not asks the experts directly? We were wondering what the elements are in the material. We tried to find it in prosthetic limbs and their use of biosensors, Then we attempted to find what elements are in biosensor tattoos again with no luck. We also need to know the chemical bonding and structure of the material. Could you help us out? Do you know any web sites that may help us find what we need?
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