| 1. |
- Al-Khafaji, Q A M, et al.
(författare)
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An Electrochemical Immunoassay for HER2 Detection
- 2012
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Ingår i: Electroanalysis. - : Wiley-VCH Verlag Berlin. - 1040-0397 .- 1521-4109. ; 24:4, s. 735-742
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a simple and sensitive approach for human epidermal growth factor receptor 2 (HER2) detection is presented, using antibody-functionalised magnetic beads coupled to screen-printed cells. The immunoassay is based on a sandwich format in which a primary monoclonal antibody anti-HER2 is coupled to protein A modified magnetic beads. The modified beads are then used to capture the protein from the sample solution and a sandwich assay is performed by adding a secondary monoclonal antibody anti-HER2 labelled with biotin. The enzyme alkaline phosphatase (AP) conjugated with streptavidin and its substrate (1-naphthyl-phosphate) are then used for the electrochemical detection by differential pulse voltammetry (DPV). The experimental conditions for the immunoassay were optimised. The performance of the assay in terms of sensitivity, reproducibility and selectivity has been studied in buffer and serum samples from hospital patients.
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| 2. |
- Tombelli, S, et al.
(författare)
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A DNA piezoelectric biosensor assay coupled with a polymerase chain reaction for bacterial toxicity determination in environmental samples
- 2000
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Ingår i: Analytica Chimica Acta. - : Elsevier Science B.V., Amsterdam.. - 0003-2670 .- 1873-4324. ; 418:1
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we report the realisation of a DNA piezoelectric biosensor coupled with the polymerase chain reaction (PCR) for the detection of a specific bacterial toxicity factor. Biotinylated 23-mer probes were immobilised on the streptavidin coated gold surface of a quartz crystal; streptavidin was covalently bound to the thiol/dextran modified gold surface. The hybridisation of the immobilised probe with a synthetic oligonucleotide was investigated; the absence of non-specific adsorption was verified using a non-complementary oligonucleotide. Many cycles of measurements can be performed on the same crystal surface by regenerating the single strand with 1 mM HCl. The same hybridisation reaction was then performed using real samples of DNA extracted from bacteria and amplified by PCR. The PCR product was a fragment of a specific gene of Aeromonas hydrophila. The piezoelectric biosensor was able to distinguish samples containing the gene or not; in this way it was possible to determine the pathogenicity of different Aeromonas strains isolated from water, vegetables or human specimens. Experiments with non-specific samples confirmed the absence of adsorption or non-specific effects on the quartz crystal treated with the reported procedure. (C) 2000 Elsevier Science B.V. All rights reserved.
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| 3. |
- Tombelli, S, et al.
(författare)
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Coupling of a DNA piezoelectric biosensor and polymerase chain reaction to detect apolipoprotein E polymorphisms
- 2000
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Ingår i: Biosensors & bioelectronics. - : Elsevier Science B.V., Amsterdam.. - 0956-5663 .- 1873-4235. ; 15:08-jul, s. 363-370
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we report the coupling of the Polymerase Chain Reaction (PCR) with a piezoelectric biosensor to detect a point mutation in a human gene. Biotinylated 23-mer probes were immobilised on the streptavidin coated gold surface of a quartz crystal; streptavidin was covalently bound to the thiol/dextran modified gold surface. The hybridisation of the immobilised probes with a short sequence (23 mer) complementary, non-complementary and mismatched DNA was investigated: the device was able to distinguish the different synthetic oligonucleotides. Many cycles of measurements can be performed on the same crystal surface regenerating the single strand of DNA with 1 mM of HCl. The same hybridisation reaction was then performed using real samples of human DNA extracted from blood and amplified by PCR, following a standard procedure for genetic detection of the polymorphism of the apolipoprotein E (apoE) gene. The procedure was able to distinguish the sequences present in the different samples, which differ only in one base: in this way it was possible distinguish between different groups of genotypes with apoE typing. Experiments with blank samples confirmed the absence of adsorption or non-specific effects on the quartz crystal treated with the reported procedure. (C) 2000 Elsevier Science S.A. All rights reserved.
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| 4. |
- Tombelli, S, et al.
(författare)
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Improved procedures for immobilisation of oligonucleotides on gold-coated piezoelectric quartz crystals
- 2002
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Ingår i: Biosensors & bioelectronics. - : Elsevier Science B.V., Amsterdam.. - 0956-5663 .- 1873-4235. ; 17:12-nov, s. 929-936
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Tidskriftsartikel (refereegranskat)abstract
- The high sensitivity and specificity of DNA hybridisation techniques makes them powerful tools for environmental or clinical analysis. This work describes the development of a DNA piezoelectric biosensor for the detection of the hybridisation reaction. Attention was focused on the choice of the coating chemistry that could be used for the immobilisation of oligonucleotides onto the gold surface of the quartz crystal. Four immobilisation procedures were tested and compared considering the amount of immobilised probe, the extent of the hybridisation reaction, the possibility of regeneration and the absence of non-specific adsorption. All the experiments were performed with oligonucleotides of 25 bases (probe, target and non-complementary oligonucleotide). The four coating methods were all based on the use of self-assembled monolayers (SAM). Three of them employed the interaction between streptavidin and biotin for the immobilisation of a biotinylated probe. Results indicated that immobilisation of a biotinylated probe on streptavidin linked to a layer of carboxylated dextran provides higher sensitivity for the detection of the hybridisation reaction, absence of non-specific adsorption and a higher stability with respect to the regeneration step. (C) 2002 Elsevier Science B.V. All rights reserved.
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