New micro-and nano-technologies for biosensor development

Recent advances in micro- and nanotechnology have produced a number of new materials which exhibit exceptional potential for the design of novel sensing strategies and to enhance the analytical performance of biosensing systems. In this thesis three different types of miniaturisation pathways were investigated for electrochemical biosensing applications. Vertically aligned carbon nanotube thin films were designed and tested as platforms for DNA immobilisation and for the development of a model electrochemical genosensor. The sensor format involved the immobilisation of oligoucleotide probes onto the sensor surface, hybridisation with the target sequence and electrochemical detection of the duplex formation. By combining such an electrode platform with an enzyme labeling, a detection limit of oligonucleotide targets in the nanomolar range was achieved. A novel magnetic particle-based microfluidic sensor was also realised by integrating a microfluidic platform with a new analytical procedure based on the use of paramagnetic beads for the detection of real PCR samples. The hybridisation reaction was carried out on probe-modified beads in a flow-through format, thus enhancing the surface area-to-volume ratio and consequently the sensitivity. Moreover, the magnetic properties of the beads greatly facilitated the delivery and removal of reagents through the microfluidic channels. This format allowed the detection of nanomolar levels of double-stranded DNA sequences, with high reproducibility and fast time of analysis. Finally, polyaniline nanotubes arranged in an ordered structure directly on gold electrode surfaces were realised and employed to create a model molecularly imprinted (MIP) polymer -sensor for catechol detection. The advantages of using nanostructures in this particular biosensing application have been evaluated by comparing the analytical performance of the sensor with an analogous non-nanostructured MIP-sensor that we had previously developed. A significantly lower limit of detection (one order of magnitude) was achieved, thus demonstrating that the nanostructures enhanced the analytical performance of the sensor.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Flat jack tests and parameter identification for diagnostic analysis of dams

Full paper III European Conference on Computational Mechanics Solids, Structures and Coupled Problems in Engineering C.A. Mota Soares et.al. (eds.

Electrochemical, electrochemiluminescence, and photoelectrochemical aptamer-based nanostructured sensors for biomarker analysis

Aptamer-based sensors have been intensively investigated as potential analytical tools in clinical analysis providing the desired portability, fast response, sensitivity, and specificity, in addition to lower cost and simplicity versus conventional methods. The aim of this review, without pretending to be exhaustive, is to give the readers an overview of recent important achievements about electrochemical, electrochemiluminescence, and photoelectrochemical aptasensors for the protein biomarker determination, mainly cancer related biomarkers, by selected recent publications. Special emphasis is placed on nanostructured-based aptasensors, which show a substantial improvement of the analytical performances

Investigations of the antioxidant properties of plant extracts using a DNA-electrochemical biosensor

In this work, the results of a method based on an electrochemical biosensor to detect DNA damage in vitro for the evaluation of the antioxidant properties of plant extracts are reported. The biosensor consisted of a dsDNA immobilized on a screen-printed electrode surface (SPE). DNA damage was promoted by the generation of the (OH)-O-center dot radicals via Fenton-type reaction. The interaction of the radical species with immobilised DNA in the absence and presence of antioxidants was evaluated by means of changes in the guanine oxidation peak obtained by square wave voltammetry. The results demonstrated that the DNA-based biosensor is suitable as a rapid screening test for the evaluation of antioxidant properties of samples. (c) 2005 Elsevier B.V. All rights reserved.2171374138

Electrochemical and photoelectrochemical biosensors for biomarker detection

A rapid and accurate medical diagnosis is essential in order to determine the health status of a patient. Nowadays, most of the clinical analyses are performed in specialized laboratory, which required specific instrumentation and trained personal, resulting in an increase of analysis costs and time. In this context, biosensors represent ideal tools capable to provide a specific and fast response together with low cost, easy use and portable size features. This work attempts to provide a review of the research progresses of electrochemical and photoelectrochemical biosensor platforms in clinical applications that have been published in recent years. Special emphasis will be devoted to discuss examples for breast cancer biomarker detection, because breast cancer, is considered the leading cause of cancer-related deaths worldwide in women, representing 15% of all cancer related amongst women, with a 6% mortality rate (based on overall cancer deaths). The manuscript is focused on aptamer-based biosensors, because, due to their stability and their relatively low cost, they have been successfully applied in many biosensor formats for breast cancer biomarker detection