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101.
We report a label-free, aptamer-based chemiluminescent biosensor. The biosensor relies upon the catalytic activity of unmodified gold nanoparticles (AuNPs) on the luminol-H(2)O(2) chemiluminescence (CL) reaction, and the interaction of unmodified AuNPs with the aptamer. The unmodified AuNPs can effectively differentiate unstructured and folded aptamer. The binding of the aptamer with the target can induce the AuNP aggregation in the presence of 0.5 M NaCl, and after aggregation the catalytic activity of the AuNPs on the luminol-H(2)O(2) CL reaction is greatly enhanced. During the assay, no covalent functionalization of the AuNPs or aptamer is required. The detection limit of thrombin was estimated to be as low as 26 fM, and the sensitivity was more than 4 orders of magnitude better than that of known AuNP-based colorimetric methods for the detection of thrombin. This aptamer-based biosensor offers the advantages of being simple, cheap, rapid, and sensitive. 相似文献
102.
A novel immunosensing strategy based on surface‐initiated atom‐transfer radical polymerization (SI‐ATRP) in combination with electrochemical detection is proposed. Specifically, 4‐acetoxystyrene (AS) has been chosen as a monomer for ATRP due to its ability to provide acetoxyl groups, which can be converted into phenolic hydroxyl groups for electrochemical detection in the presence of tyrosinase. A controlled radical polymerization reaction of 4‐acetoxystyrene at 60 °C was triggered after immobilization of initiator molecules on an electrode surface. The growth of long‐chain polymeric materials increased the concentration of phenolic hydroxyl groups, which in turn significantly enhanced the electrochemical signal output. Polymerization conditions, such as temperature and duration, monomer concentration, and the catalyst/monomer ratio have been optimized. The in situ surface‐initiated ATRP was confirmed by scanning electron microscope (SEM) images and X‐ray photoelectron spectroscopy (XPS) analysis. Cyclic voltammetric investigation revealed a pair of well‐defined oxidation and reduction peaks at 0.232 and 0.055 V, which corresponded to the redox behavior of catechol/o‐quinone on the electrode surface. The proposed approach has been successfully extended to immune recognition. A detection limit of 0.3 ng mL?1 for rabbit immunoglobulin G (IgG) as a model antigen has been achieved. Despite the limited availability of the IgG antibody, this technology might also be expanded to the detection of other proteins and DNA. 相似文献
103.
A fluorometric sensor for detection and identification of biogenic amines with carboxylic acid modified tetraphenylethenes (TPEs) based on aggregation-induced emission (AIE) is reported. A mixture of the carboxylic acid substituted TPE and biogenic amines displayed a blue emission on aggregation, which serves as a "turn-on" fluorescent sensor for the amines, the degree of fluorescence enhancement being dependent on the amine. The chromic responses were utilized to distinguish the amines. A fluorometric sensor array of three TPEs with carboxylic acid groups was shown to identify accurately 10 different amines, including biogenic amines. The response patterns were systematically classified by using linear discriminant analysis (LDA) with 98% classification accuracy. Additional information on the concentration of histamine in a "tuna fish matrix" as an example was assessed by the further analysis of the fluorescence intensity, demonstrating a test for food freshness and quality. 相似文献
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Arnaldo C. Pereira Alexandre Kisner César R. T. Tarley Lauro T. Kubota 《Electroanalysis》2011,23(6):1470-1477
A reagentless amperometric biosensor sensitive to lactate was developed. The sensor employs a carbon paste electrode modified with lactate oxidase (LOx) and Meldola’s Blue (MB) adsorbed on silica gel coated with niobium oxide. The dependence on the biosensor response was investigated in terms of pH, supporting electrolyte, ionic strength, lactate oxidase (LOx) amounts and applied potential. The biosensor showed an excellent operational stability (96 % of the activity was maintained after 150 determinations) and storage stability (allowing measurements for more than 1.5 months, when stored in a refrigerator). The proposed biosensor also presented good sensitivity allowing lactate quantification at levels down to 6.5×10?7 mol L?1. Moreover, the biosensor showed a good linear response range (from 0.1 to 5.0 mmol L?1 for lactate). Lactate analysis in biological samples such as blood was also performed. The precision of the data obtained by the proposed biosensor showed reliable results for real complex matrices. 相似文献
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Mohammad Saeid Hejazi Mohammad Hossein Pournaghi‐Azar Esmaeel Alipour Elaheh Dalir Abdolahinia Sanam Arami Hosnieh Navvah 《Electroanalysis》2011,23(2):503-511
In spite of the extensive attention paid on the development of various DNA detection strategies, very few studies have been reported regarding direct detection of DNA sequence and mutation in dsDNA. Here, we describe the feasibility of detection and discrimination of target DNA sequences and single base mutations (SBM) directly in double‐stranded oligonucleotides and PCR products without the need for denaturation of the target dsDNA samples. This goal was achieved by employing a peptide nucleic acid (PNA) chain, self‐assembled on the gold electrode as a probe, which binds to dsDNA and forms PNA‐dsDNA hybrid. 相似文献
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