Download the Free Unbound MEDLINE PubMed App to your smartphone or tablet.
Available for iPhone, iPad, iPod touch, and Android.
Biosensors bioelectronics [journal]
- Selective room temperature phosphorescence sensing of target protein using Mn-doped ZnS QDs-embedded molecularly imprinted polymer. [JOURNAL ARTICLE]
- Biosens Bioelectron 2013 Apr 25.:216-223.
The direct correlation between disease states and protein levels makes the sensitive, convenient, and precise detection of proteins the focus of scientific research. This paper demonstrates a new strategy for producing phosphorescent molecularly imprinted polymer (MIP) for specific recognition of a target protein. The technique provides surface graft imprinting in aqueous solutions using vinyl modified Mn-doped ZnS QDs as supports, methacrylic acid and acrylamide as functional monomers, and bovine hemoglobin as a template. The QDs act as antennae for recognition signal amplification and optical readout, and the MIP shell provides analyte selectivity and prevents interfering molecules from coming into contact with the QDs. The small particle sizes and the nontoxicity of the MIP-QDs composites allows for good dispersibility and stability in an aqueous solution. Under optimal conditions, good linear correlations were obtained for bovine hemoglobin over the concentration range from 1.0×10(-7) to 5.0×10(-6)molL(-1) and with recoveries of 96.7-103.8% and 92.6-94.2% for urine and serum samples, respectively. The long lifetime of the MIP-QDs composites phosphorescence avoids interference due to autofluorescence and scattering of the biomatrix, facilitating composites' application for detection of bovine hemoglobin in biological fluids.
- Dendrimer-encapsulated copper as a novel oligonucleotides label for sensitive electrochemical stripping detection of DNA hybridization. [JOURNAL ARTICLE]
- Biosens Bioelectron 2013 Apr 28.:210-215.
This paper describes the synthesis and characterization of a novel electrochemical label for sensitive electrochemical stripping detection of DNA hybridization based on dendrimer-encapsulated copper. The generation 4.5 (G 4.5) carboxyl-terminated poly(amidoamine) dendrimer with a trimesyl core was used as a template for synthesis of Cu(2+)/dendrimer nanocomposites (Cu-DNCs). Ratios of Cu(2+)/dendrimer were optimized in order to obtain stable nanocomposites with maximal copper loading in the interior of a polymeric shell. Cu-DNCs labeled DNA probe was employed for determining a target ssDNA immobilized on multi-walled carbon nanotubes-modified glassy carbon electrode (GCE) based on a specific hybridization reaction. The hybridization events were monitored by electrochemical detection of Cu anchored on the hybrids after the release in a diluted nitric acid by anodic stripping differential pulse voltammetry (ASDPV). The results showed that only a complementary sequence could form a dsDNA with the Cu-DNCs DNA probe and give an obvious electrochemical signal. The non-complementary sequence exhibited negligible signal change compared with the blank measurement (means: the electrode containing no target DNA incubating in hybridization buffer solution containing Cu-DNCs DNA probe for a certain time). The use of Cu encapsulated-dendrimer as tags and ASDPV for the detection of the released Cu ions could enhance the hybridization signal, and result in the increase of the sensitivity for the target DNA. Under the conditions employed here, the detection limit for measuring the full complementary sequence is down to pM level.
- Electrochemical magneto immunosensor for the detection of anti-TG2 antibody in celiac disease. [JOURNAL ARTICLE]
- Biosens Bioelectron 2013 Apr 17.:203-209.
An electrochemical magneto immunosensor for the detection of anti-transglutaminase antibodies (ATG2) in celiac disease was developed. The immunological reaction is performed on magnetic beads (MBs) as a solid support in which the transglutaminase enzyme (TG2) is covalently immobilized (TG2-MB) and then ATG2 were revealed by an antibody labeled with peroxidase. The electrochemical response of the enzymatic reaction with o-phenilendiamine and H2O2 as substrates by square wave voltammetry was correlated with the ATG2. Graphite-epoxi composite cylindrical electrodes and screen printed electrodes were used as transducers in the immunosensor. A total number of 29 sera from clinically confirmed cases of celiac disease and 19 negative control sera were tested by the electrochemical magneto immunosensor. The data were submitted to the receiver-operating characteristic plot (ROC) analysis which indicated that 16.95 units was the most effective cut-off value (COV) to discriminate correctly between celiac and non-celiac patients. Using this point for prediction, sensitivity was found to be 100%, while specificity was 84%.
- An electrochemical acetylcholine sensor based on lichen-like nickel oxide nanostructure. [JOURNAL ARTICLE]
- Biosens Bioelectron 2013 Apr 11.:197-202.
Lichen-like nickel oxide nanostructure was synthesized by a simple method and characterized. The nanostructure was then applied to modify a carbon paste electrode and for the fabrication of a sensor, and the electrocatalytic oxidation of acetylcholine (ACh) on the modified electrode was investigated. The electrocatalytic efficiency of the nickel oxide nanostructure was compared with nickel micro- and nanoparticles, and the lichen-like nickel oxide nanostructure showed the highest efficiency. The mechanism and kinetics of the electrooxidation process were investigated by cyclic voltammetry, steady-state polarization curve and chronoamperometry. The catalytic rate constant and the charge transfer coefficient of ACh electrooxidation by the active nickel species, and the diffusion coefficient of ACh were reported. A sensitive and time-saving hydrodynamic amperometry method was developed for the determination of ACh. ACh was determined with a sensitivity of 392.4mAM(-1)cm(-2) and a limit of detection of 26.7μM. The sensor had the advantages of simple fabrication method without using any enzyme or reagent and immobilization step, high electrocatalytic activity, very high sensitivity, long-term stability, and antifouling surface property toward ACh and its oxidation product.
- Toward embedded laboratory automation for smart lab-on-a-chip embryo arrays. [JOURNAL ARTICLE]
- Biosens Bioelectron 2013 Apr 30.:188-196.
Lab-on-a-Chip (LOC) biomicrofluidic technologies are rapidly emerging bioanalytical tools that can miniaturize and revolutionize in situ research on embryos of small vertebrate model organisms such as zebrafish (Danio rerio) and clawed African frog (Xenopus laevis). Despite considerable progress being made in fabrication techniques of chip-based devices, they usually still require excessive and manual actuation and data acquisition that significantly reduce throughput and introduce operator-related analytical bias. This work describes the development of a proof-of-concept embedded platform that integrates an innovative LOC zebrafish embryo array technology with an electronic interface to provide higher levels of laboratory automation for in situ biotests. The integrated platform was designed to perform automatic immobilization, culture and treatment of developing zebrafish embryos during fish embryo toxicity (FET) biotests. The system was equipped with a stepper motor driven stage, solenoid-actuated pinch valves, miniaturized peristaltic pumps as well as Peltier heating module. Furthermore, a Field Programmable Gate Array (FPGA) was used to implement an embedded hardware/software solution and interface to enable real-time control over embryo loading and immobilization; accurate microfluidic flow control; temperature stabilization and also automatic time-resolved image acquisition of developing zebrafish embryos. This work presents evidence that integration of embedded electronic interfaces with microfluidic chip-based technologies can bring the Lab-on-a-Chip a step closer to fully automated analytical systems.
- A novel graphene-DNA biosensor for selective detection of mercury ions. [JOURNAL ARTICLE]
- Biosens Bioelectron 2013 Apr 19.:180-187.
A novel electrochemical biosensor for sensitive and selective detection of mercury (II) ions (Hg(2+)) based on a DNA grafted graphene is proposed. Graphene oxide (GO) was reduced by dopamine, and then the single-strand probe DNA modified at the 5'-end with an alkylamino modifier (NH2-ssDNA) was grafted on the reduced graphene oxide (RGO) surface via Michael addition reaction. In the presence of Hg(2+), the target DNA with four thymine-thymine (T-T) mismatches would hybridize with the probe DNA on the glassy carbon electrode (GCE) through T-Hg(2+)-T coordination chemistry. The hybridization of the two oligonucleotides leads to the increase in the peak currents of [Ru(NH3)6](3+), which could be used for electrochemical sensing of Hg(2+). The difference in the value of the peak currents of [Ru(NH3)6](3+) before and after DNA hybridization was linear with the concentration of Hg(2+) in the range from 8.0×10(-9) to 1.0×10(-7)M with a linear coefficiency of 0.996. The detection limit was 5.0×10(-9)M (S/N=3). The proposed electrochemical biosensor is rapid, convenient and low-cost for effective sensing of Hg(2+). Particularly, the proposed method was applied successfully to the determination of Hg(2+) in real environmental samples.
- A new quantitative experimental approach to investigate single cell adhesion on multifunctional substrates. [JOURNAL ARTICLE]
- Biosens Bioelectron 2013 Apr 21.:172-179.
Cell adhesion is fundamental for the organization of cells in multicellular organisms since it has a key role in several physiological functions that drive tissue formation and development. A better knowledge of the affections that influence the adhesion capability of cells in several pathologies, such as cancer diseases or multiple sclerosis could enable the development of new therapeutical strategies. Whereas the optimal control of cell adhesion and growth on new technological materials is a primary issue in modern tissue engineering, few techniques are able to provide quantitative and reliable results on cell adhesion. We present a method that enables the investigation of cell adhesion at the single cell level and provides the capability to test the adhesion of a single cell on multifunctional substrates. To reach this goal we applied single cell force spectroscopy (SCFS) on custom designed patterns of molecules prepared on a rigid substrate by using a cantilever based molecule deposition tool, and we tested the adhesion of Chinese Hamster Ovary cells and Human Embrionic Kidney cells on two polyelectrolytes that are widely used as adhesive factors for cells growth: Polyethylenimine and Poly-D-Lysine. Our results confirm the common hypothesis on the mechanism of adhesion promotion by protonated molecules. Optimizations of the experimental settings of SFCS experiment are introduced here. The presented technique offers the unique opportunity to be extended to the study of cell adhesion on an unlimited number molecular species.
- A new insight into electrochemical microRNA detection: A molecular caliper, p19 protein. [JOURNAL ARTICLE]
- Biosens Bioelectron 2013 Apr 20.:165-171.
microRNA (miRNA) has drawn a great attention in biomedical research due to its functions on biological processes. Detection of miRNAs is a big challenge since the amount present in real samples is very low and the length of them is short. In this study, for the first time an electrochemical biosensor for detection of mir21 using the oxidation signal of protein 19 (p19) as a molecular caliper was designed. The proposed method enables detection of mir21 in direct, rapid, sensitive, inexpensive and label-free way. Binding specificity of the p19 to 20-23 base pair length double stranded RNA (dsRNA) and direct/water-mediated intermolecular contacts between the fusion protein and miRNA allows detection of miRNA-antimiRNA hybrid structure. The detection of mir21 was achieved in picomole sensitivity through the changes of intrinsic p19 oxidation signals observed at +0.80V with Differential Pulse Voltammetry (DPV) and the specifity of the designed sensor was proved by control studies.
- Enhancing of intensity of fluorescence by DEP manipulations of polyaniline-coated Al2O3 nanoparticles for immunosensing. [JOURNAL ARTICLE]
- Biosens Bioelectron 2013 Apr 10.:158-164.
A novel modification of low-cost Al2O3 nanoparticles (Al2O3 NPs) for antibody-protein immunosensing is proposed. The modified NPs are utilized to enhance the intensity of fluorescence in a dielectrophoretic (DEP) chip with a microelectrode array. The surface of the Al2O3 NPs is modified by ionic polyaniline (PANDB) rather than the conventional silane (3-aminopropyltrimethoxysilane) to conjugate the antibody on the outer shell. After the PANDB-Al2O3 NPs is functionalized to form probes, a DEP chip with a vertical non-uniform electric field that is produced by top and bottom electrodes condenses and immobilizes the nanoprobes on the surface of the electrodes by positive DEP force for immunosensing of the fluorescent protein. Additionally, each microelectrode array can be individually controlled with/without DEP manipulation using a computer program. Experimental results indicate that PANDB-based nanoprobes provide more rapid and sensitive immunosensing than those having undergone conventional silane modification. During immunosensing, fluorescence intensity can be doubled by the application of extra DEP force. The individual control of NPs on the microelectrode array has great potential for applications in multi-antibody arrays in a single chip for immunosensing.
- Improving the Design of a MscL-Based Triggered Nanovalve. [JOURNAL ARTICLE]
- Biosens Bioelectron 2013; 3(1):171-184.
The mechanosensitive channel of large conductance, MscL, has been proposed as a triggered nanovalve to be used in drug release and other nanodevices. It is a small homopentameric bacterial protein that has the largest gated pore known: greater than 30 Å. Large molecules, even small proteins can be released through MscL. Although MscL normally gates in response to membrane tension, early studies found that hydrophilic or charged residue substitutions near the constriction of the channel leads to pore opening. Researchers have successfully changed the modality of MscL to open to stimuli such as light by chemically modifying a single residue, G22, within the MscL pore. Here, by utilizing in vivo, liposome efflux, and patch clamp assays we compared modification of G22 with that of another neighboring residue, G26, and demonstrate that modifying G26 may be a better choice for triggered nanovalves used for triggered vesicular release of compounds.