Biosensors and Bioelectronics - IFM - Linköping University

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introduce a metallic core, giving the particle optical, magnetic, or hyperthermic properties. The goal of this programme is to develop unimolecular micelles with magnetic resonance imaging (MRI) contrast and hyperthermic characteristics for targeted drug delivery. These novel micelles will be composed of three key components: (i) a chemotherapeutic agent doxorubicin that will be released from polymeric micelles through a pH-dependent mechanism; (ii) a biological ligand, i.e., specific aptamer that can target tumor cells and subsequently induce receptormediated endocytosis for cell uptake; and (iii) a metallic core for ultrasensitive MRI or hyperthermic properties. Molecularly Imprinted Nanoparticles The high selectivity and affinity of molecularlyimprinted polymer (MIP) nanoparticles offers a promising approach to develop a new generation of biosensors, therapeutics and imaging agents, incorporating plastic receptors with desirable catalytic, affinity and DNA sequence-specific properties. Compared to other types of biosensors, which use biologically active molecules such as enzyme, antibody and DNA strands immobilised onto the electrode surface as sensing elements, biosensors based on MIPs offer three key advantages: 1) high affinity and selectivity to the imprinted template (i.e., the target molecules); 2) superior stability compared with those using natural biomolecules in the biosensor structure; and 3) ease of fabrication and adaptation for various types of biosensors. Our MIP research relates to the development of biomimetic biosensors, for biomarkers of disease and for the direct detection of genetic and infectious diseases. (A) Electrochemical preparation of ss-ODN imprinted MIP electrode and (B) Re-usable biosensor to recognise sequence-specific ss-ODN. Cardiac troponin immunosensor. LIST (2011-12) 200k SEK. This project aims to design a tunable cardiac troponin immunosensor with a sensitivity in the picograms/mL range or less, and a doubleswitchable cardiac troponin immunosensor using core-shell nanocomposite. The model strategy will aid in the effective diagnosis of acute coronary syndrome. Ideally, it will make significant contributions to advanced bioelectronics and material sciences, leading to construction of ultra sensitive immunosensors. Computational Design of Aptamers Under an ongoing programme of collaboration with the University of Florence, we have elucidated an entirely new approach to the selection of aptamers by using computational approach. Starting from information on the 15-mer thrombin binding aptamer (TBA), a library of mutated DNA sequences was generated and screened using Shapegauss a shape-based scoring function from Openeye Software to generate computationally derived binding scores. The TBA and three other mutated oligonucleotides, selected on the basis of their binding score, were incorporated into surface plasmon resonance (SPR) biosensors. By reducing the ionic strength in order to match the simulated condition, the analytical performances of the four oligonucleotide sequences were compared using signal amplitude, sensitivity, linearity and reproducibility. The experimental results were in agreement with the simulation findings. This work could have a significant impact on the efficiency and effectiveness of aptamer selection for sensors and diagnostics, by facilitating the partial pre-selection of aptamer sequences to be further tested in an experimental screening process. Reagentless Genosensor Dr. Valerio Beni is collaborating with Prof. Ciara O'Sullivan, in the development of novel approaches for performing electrochemical melting curves analysis. This work, carried out at the Universitat Rovira i Virgili, Tarragona, Spain aims at the development of novel electrochemical labels suitable for conjugation with oligonucleotides and subsequent incorporation in PCR products. The presence of the electrochemical labels will allow the hybridisation between a PCR product and surface immobilised oligonucleotides probes to be followed as a function of the solution/surface temperature, using simple and inexpensive hardware.
Loss in hybridisation, melting of the duplex results in a reduction in the electrochemical response. Studies of the melting temperature of probe/PCR product are foreseen as an improved method to allow rapid and effective identification of specific genetic sequences. Salivary Amylase (sAA) as a Stress Marker. NovaMedTech, New Tools for Health and Innovation Bridge (2011-2012), 1m SEK. A pilot study on the associations between sAA, psychosocial factors, self-rated health and inflammation markers has been conducted in cooperation with researchers at the Health University having a saliva bank within a study called Life conditions, Stress and Health. Levels of sAA just after awakening were positively associated with depression scores and level of ongoing inflammation, and negatively associated with selfrated health. Levels of sAA 30 minutes after awakening and just before going to bed point in the same direction, but may be influenced by recent daily activity to a higher extent. The findings support the hypothesis that sAA might be a reliable marker of ANS activity in saliva. Reaction kinetics due to amylase activity can be measured with simple instrumentation using a light source (LED) and a detector (phototransistor) or with a disposable plastic electrochemical strip. Preliminary comparison with an established method for determination of saliva amylase activity is shown below. Pink triangles = measurements on diluted saliva, blue = standard method. 4,00 3,50 3,00 2,50 2,00 1,50 1,00 0,50 Calibration curve 0,00 0 20000 40000 60000 80000 100000 120000 A spin-off has been initiated to develop a commercially viable biosensor system to monitor wellness and therapy effectiveness and about one million SEK in seed funding from several Swedish innovation funding agencies has been secured. A preliminary market study has been completed and initial contacts for clinical studies have been established. With support from LiU Innovations and Uppsala University patent office, the patent strategy is underway. Activities continue to develop a prototype and conduct a clinical benefit study, which are fundamental to demonstrate commercial viability. The success of this endeavor demonstrates how our research can generate applications that improve quality of life and increase the sustainability of healthcare. Reagent paper Instrumentation Skin Emissions studies for Bed Sore Prevention. NovaMedTech Pressure ulcers are a major problem for bed-ridden patients, causing pain and intense suffering for the individual. Furthermore, treatment is very costly and labour intensive. A lot can be gained therefore if early precursors of pressure ulcers can be spotted and measures taken before an ulcer occurs. In collaboration with researchers at the Health University in Linköping and at the University of Rome “Tor Vergata”, we have performed an initial study to find out if there is a difference in the emissions from the skin of compressed tissue compared with uncompressed tissue. The experiments were performed on hospitalised patients in an intensive care unit and on healthy volunteers. This GC-MS study indicates that difference in general emission patterns are seen between hospitalised and healthy people, respectively. Furthermore within each group it was possible to differentiate between compressed and uncompressed tissue. This lays the foundation for the development of smart technology to prevent this costly and damaging trauma. Artificial Olfaction A further collaboration with the University of Rome “Tor Vergata” in the area of artificial olfaction and colour indicators for volatile organic compounds has resulted in improved modeling of the olfactory system based on optical chemical sensing, where each pixel in a response image is regarded as an olfactory receptor neuron. Our results indicate that the average firing rate of the output spike sequences shows the best separation among the experienced vapours, however the latency code is able in a shorter time to correctly discriminate all the tested volatile compounds. This behavior is qualitatively similar to those recently found in natural olfaction, and in particular it provides a practical route to tailor the measurement conditions of artificial olfactory systems, defining for each specific case a proper measurement time Bioelectronics We are currently focusing on electroactive surfaces and scaffolds for regenerative medicine as a part of the LiU Integrative Regenerative Medicine (IGEN)
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