17 results found
Raghavan VS, O'Driscoll B, Bloor JM, et al., 2021, Emerging graphene-based sensors for the detection of food adulterants and toxicants-A review, FOOD CHEMISTRY, Vol: 355, ISSN: 0308-8146
Li B, Zhang G, Tahirbegi IB, et al., 2021, Monitoring amyloid-β 42 conformational change using a spray-printed graphene electrode, Electrochemistry Communications, Vol: 123, ISSN: 1388-2481
Up to now, the reproducibility and stability of graphene-based electrochemical sensors have represented an obstacle to the development of practical biosensing techniques. In this paper we report a cost-effective and highly reproducible graphene-based electrochemical sensing platform to monitor the kinetic conformational change of amyloidogenic proteins. The sensor surface is spray-printed with a graphene oxide layer and then electrochemically reduced to achieve excellent sensitivity to the redox current. The reproducibility of these sensors in terms of redox peak position, intensity and electroactive area has been proved to be high. These sensors are used to monitor the conformational changes of amyloid-β 42 via the change in the oxidation current of tyrosine, which is caused by different electrochemical accessibility during the aggregation process. The aggregation process detected at these graphene electrochemical sensors shows a good correlation with the fluorescence assay. The proposed platform provides a complementary technique to aid understanding of the detailed process of amyloidogenic protein aggregation and the mechanism of neurodegenerative diseases as well as helping to promote the development of disease-prevention strategies.
Li B, Tan H, Jenkins D, et al., 2020, Clinical detection of neurodegenerative blood biomarkers using graphene immunosensor, Carbon, Vol: 168, Pages: 144-162, ISSN: 0008-6223
Accurate detection of blood biomarkers related to neurodegenerative diseases could provide a shortcut to identifying early stage patients before the onset of symptoms. The specificity, selectivity and operational requirements of the current technologies, however, preclude their use in the primary clinical setting for early detection. Graphene, an emerging 2D nanomaterial, is a promising candidate for biosensing which has the potential to meet the performance requirements and enable cost-effective, portable and rapid diagnosis. In this review, we compare graphene-based immunosensing technologies with conventional enzyme-linked immunosorbent assays and cutting-edge single molecule array techniques for the detection of blood-based neurodegenerative biomarkers. We cover the progress in electrical, electrochemical and optical graphene-based immunosensors and outline the barriers that slow or prevent the adoption of this emerging technology in primary clinical settings. We also highlight the possible solutions to overcome these barriers with an outlook on the future of the promising, graphene immunosensor technology.
Gil B, Li B, Gao A, et al., 2020, Miniaturized Piezo Force Sensor for a Medical Catheter and Implantable Device, ACS APPLIED ELECTRONIC MATERIALS, Vol: 2, Pages: 2669-2677, ISSN: 2637-6113
Li B, Gil B, Power M, et al., 2019, Carbon-nanotube-coated 3D microspring force sensor for medical applications, ACS Applied Materials and Interfaces, Vol: 11, Pages: 35577-35586, ISSN: 1944-8244
Flexible electronic materials combined with micro-3D fabrication present new opportunities for wearable biosensors and medical devices. This Research Article introduces a novel carbon-nanotube-coated force sensor, successfully combining the advantages of flexible conductive nanomaterials and the versatility of two photon polymerization technologies for creating functional 3D microstructures. The device employs carbon-nanotube-coated microsprings with varying configurations and geometries for real-time force sensing. To demonstrate its practical value, the device has first been embodied as a patch sensor for transcutaneous monitoring of human arterial pulses, followed by the development of a multiple-point force-sensitive catheter for real-time noninvasive intraluminal intervention. The results illustrate the potential of leveraging advanced nanomaterials and micro-3D-printing for developing new medical devices.
Wu J, Yuan H, Li L-Y, et al., 2019, Mathematical modelling of microtubule-tau protein transients: Insights into the superior mechanical behavior of axon, APPLIED MATHEMATICAL MODELLING, Vol: 71, Pages: 452-466, ISSN: 0307-904X
Li B, Tan H, Anastasova-Ivanova S, et al., 2019, A bioinspired 3D micro-structure for graphene-based bacteria sensing, Biosensors and Bioelectronics, Vol: 123, Pages: 77-84, ISSN: 0956-5663
Nature is a great source of inspiration for the development of solutions for biomedical problems. We present a novel biosensor design utilizing two-photon polymerisation and graphene to fabricate an enhanced biosensing platform for the detection of motile bacteria. A cage comprising venous valve-inspired directional micro-structure is fabricated around graphene-based sensing electronics. The asymmetric 3D micro-structure promotes motile cells to swim from outside the cage towards the inner-most chamber, resulting in concentrated bacteria surrounding the central sensing region, thus enhancing the sensing signal. The concentrating effect is proved across a range of cell cultures - from 101 CFU/ml to 109 CFU/ml. Fluorescence analysis shows a 3.38–3.5 times enhanced signal. pH sensor presents a 2.14–3.08 times enhancement via the detection of cellar metabolite. Electrical measurements demonstrate an 8.8–26.7 times enhanced current. The proposed platform provides a new way of leveraging bio-inspired 3D printing and 2D materials for the development of sensing devices for biomedical applications.
Li B, Famili M, Pensa E, et al., 2018, Cross-plane conductance through a graphene/molecular monolayer/Au sandwich, Nanoscale, Vol: 10, Pages: 19791-19798, ISSN: 2040-3364
The functionalities offered by single-molecule electrical junctions are yet to be translated into monolayer or few-layer molecular films, where making effective and reproducible electrical contact is one of the challenging bottlenecks. Here we take a significant step in this direction by demonstrating that excellent electrical contact can be made with a monolayer biphenyl-4,4′-dithiol (BPDT) molecular film, sandwiched between gold and graphene electrodes. This sandwich device structure is advantageous, because the current flows through the molecules to the gold substrate in a ‘cross-plane’ manner, perpendicular to the plane of graphene, yielding high-conductance devices. We elucidate the nature of the cross-plane graphene/molecule/Au transport using quantum transport calculations and introduce a simple analytical model, which captures generic features of the current–voltage characteristic. Asymmetry in junction properties results from the disparity in electrode electrical properties, the alignment of the BPDT HOMO–LUMO energy levels and the specific characteristics of the graphene electrode. The experimental observation of scalability of junction properties within the junction area, in combination with a theoretical description of the transmission probability of the thiol–graphene contact, demonstrates that between 10% and 100% of the molecules make contact with the electrodes, which is several orders of magnitude greater than that achieved to date in the literature.
Black NCG, Rungger I, Li B, et al., 2018, Adsorption dynamics of CVD graphene investigated by a contactless microwave method, 2D Materials, Vol: 5, ISSN: 2053-1583
We use a contactless microwave dielectric resonator gas sensing platform to study the adsorption dynamics of NO2 gas present in air onto a graphene surface. The use of microwaves removes the need for metal contacts that would otherwise be necessary for traditional conductivity measurements, and therefore allows non-invasive determination of NO2 concentrations to sub parts per million. As a result, gas−metal interactions and localised graphene doping in the vicinity of metal contacts are eliminated, with the advantage that only graphene−gas adsorbate interactions are responsible for the measured signal. We show that the sensor response for all considered concentrations can be described using a surface coverage dependent Langmuir model. We demonstrate that the possible variation of the NO2 binding energy, which is frequently considered as the main parameter, plays only a secondary role compared to the rising adsorption energy barrier with increasing NO2 coverage. The continuous distribution of the properties of the graphene adsorption sites used in the theoretical model is supported by our Kelvin probe and Raman surface analysis. Our results demonstrate that the non-invasive microwave method is a promising alternative platform for gas sensing. Moreover it provides valuable insights towards the understanding of the microscopic processes occurring in graphene based gas sensors, which is a key factor in the realization of reproducible and optimized device properties.
Black NCG, Liu CG, Pearce R, et al., 2017, Graphene gas sensing using a non-contact microwave method, NANOTECHNOLOGY, Vol: 28, ISSN: 0957-4484
We report a non-contact CVD graphene gas sensing method that utilises a high Q microwave dielectric resonator perturbation technique. A graphene sample is coupled to the evanescent field of a dielectric resonator whereupon nitrogen dioxide (NO2), a p-doping gas, is detected by monitoring the change in the linewidth and frequency of the resonant mode. The resonant peak shape is dependent on the number of carriers in the graphene sheet. Therefore, the linewidth perturbation can be converted to a measurement of the graphene sheet resistance. To demonstrate the strength of this technique, sensor response curves for NO2 at different concentrations and temperatures are measured showing sub ppm sensitivity. This technique eliminates interactions between the trace gas and metal contacts that otherwise effect the sensor response of the graphene device.
Li B, Pan G, Suhail A, et al., 2017, Deep UV hardening of photoresist for shaping of graphene and lift-off fabrication of back-gated field effect biosensors by ion-milling and sputter deposition, CARBON, Vol: 118, Pages: 43-49, ISSN: 0008-6223
Suhail A, Islam K, Li B, et al., 2017, Reduction of polymer residue on wet-transferred CVD graphene surface by deep UV exposure, APPLIED PHYSICS LETTERS, Vol: 110, ISSN: 0003-6951
Li B, Pan G, Avent ND, et al., 2016, A Simple Approach to Preparation of Graphene/Reduced Graphene Oxide/Polyallylamine Electrode and Their Electrocatalysis for Hydrogen Peroxide Reduction, JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY, Vol: 16, Pages: 12805-12810, ISSN: 1533-4880
Li B, Pan G, Avent ND, et al., 2015, Graphene electrode modified with electrochemically reduced graphene oxide for label-free DNA detection, BIOSENSORS & BIOELECTRONICS, Vol: 72, Pages: 313-319, ISSN: 0956-5663
Li B, Pan G, Jamil NY, et al., 2015, Shielding technique for deposition of Au electrical contacts on graphene by sputtering, JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A, Vol: 33, ISSN: 0734-2101
Awan SA, Pan G, Al Taan LM, et al., 2015, Radio-frequency transport Electromagnetic Properties of chemical vapour deposition graphene from direct current to 110 MHz, IET CIRCUITS DEVICES & SYSTEMS, Vol: 9, Pages: 46-51, ISSN: 1751-858X
Pan G, Li B, Heath M, et al., 2013, Transfer-free growth of graphene on SiO2 insulator substrate from sputtered carbon and nickel films, CARBON, Vol: 65, Pages: 349-358, ISSN: 0008-6223
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