Nanosensor Technologies for Monitoring- materials and methods
The Royal Society of Chemistry, AAMG, London, 7th November 2012.
Anna Maria Pisanelli- University of Manchester.
Operating on the scale of atoms and molecules, emerging nanotechnologies promise dramatic changes in sensor designs and capabilities. This meeting offered the chance to meet scientists carrying out research in the field of nanotechnology to produce highly specialized sensors. The meeting allowed a mixture of experts and young researchers to present a range of topics reflecting the variety of nanotechnological interests in the UK and abroad.
Duncan Graham from the University of Strathclyde presented the functionalisation of gold and silver nanoparticles used in different studies including detection of biomolecules at ultra low levels, immunochemistry and as substrates for surface enhanced resonance Raman scattered based imaging approaches. The presentation covered the full range of design and the biological properties of functionalized nanoparticles in relation to specific disease states. Continuing the medical theme, from the Institute of Occupational Medicine, Edinburgh, Lang Tran introduced to the audience potential hazards and benefits of nanomaterials. The challenge for nanotechnology is to determine which physico-chemical characteristics of the nanomaterials drive their toxicity. In nanomedicine nanoparticles are used for targeted detection and drug delivery at the sites of the lesion. Nanoparticles can represent potential hazards to the exposed worker but they have potential benefits in nanomedicine. John Pickup from Kings College, London presented interesting results on the application of nanomedicine in diabetes. Nanosecond fluorescence lifetime photonics have been used for glucose detection. Protoype fibre-opic glucose sensors have been constructed and tested and it was demonstrated that galactose binding microvescicles might have potential to be implanted in humans as a non invasive glucose sensor.
Sergey Piletsky and Alessandro Poma from The University of Cranfield, in two complementary presentations, illustrated the automatic synthesis of Molecular Imprinted Polymers(MIPs). MIPs are generic alternatives to antibodies and natural receptors in diagnostics and separation. An efficient and flexible method for automatic synthesis of MIPs using a solid phase photoreactor was presented. The photoreactor developed is capable of producing 20mg of artificial antibodies per day.The affinity of the synthesised nanoparticles allows detection at nanomolar level which makes the MIPs suitable for application in biochemical assays, sensors and affinity chromatography. The MIPs will be very useful in the development of new sensor devices and assays that utilize stable and inexpensive plastic antibodies with integrated recognition and signalling functionalities.
Maria Daniela Angione from The University of Manchester presented a low-cost Organic Field- effect Transistor realized on a flexible substrate, using Poly(Vinyl Alcohol) (PVA) as the gate dielectric, Poly(3-Hexylthiophene) as organic semiconductor and a nano-emulsion of Polyaniline (PANI) in water as gate material. Advantages of this device are low-cost manufacturing process, compatibility with flexible substrates and relatively high dielectric constant for PVA. The good electrical performance obtained and the high sensitivity of nanodispersed PANI to ammonia indicates that this device can be used to assess food freshness by detecting the ammonia.
Caenorhabditis elegans is a non-parasitic soil nematode which has been used to model biological processes such aging and drug response. Vereen M Chauhan from the University of Nottingham presented the results of a study that he carried out by using C. Elegans intestinal tract as a suitable model to discover new target and therapeutics for acid suppression in mammals to overcome diseases such as gastro-oesophageal reflux or Zollinger-Ellison syndrome. Mapping the pH through the C. Elegans intestinal tract could enhance the understanding disease progression and the role of the therapy in acid suppression.
Elena Tuccori from the University of Manchester explained how Odorant Binding Protein (OBP) can be used as nanoparticles for the detection of food odour in both vapour and liquid phase. OBP’s combined with different kinds of transducer can be employed in several applications. Recombinant OBP nanoparticles from a selection of vertebrate and invertebrate OBP’s have been prepared and their sensing characteristics investigated with different types of transducer platforms. OBPs have been immobilised on quartz microbalances and on screen printed gold electrodes that allowed impedance and capacitance measurements. The results demonstrated that OBPs can be used as the sensitive layer for the detection of odours at ppb levels.
Alejandro Alija from Inginieros Asesores, Spain gave a presentation on detection of pollutants in the air and in water using different methods. The work shows how nanosensor technologes are quite ready for real applications in indoor air monitoring to detect pollutants. The combination of both solid state sensors based on metal oxide semiconductor nanostructured materials and modern electrochemical cells provide many advantages for pollutants monitoring.
Ehsan Danesh from the University of Manchester talked about highly sensitive ammonia sensors on flexible substrates. Fabrication of low-cost and low-power chemical sensors on flexible substrates is aimed at opening new applications in environmental monitoring and smart food packaging. Polyaniline (PANI), known for its excellent gas sensing properties, reversibly interacts with ammonia causing a significant decrease in its conductivity. By utilizing composites of PANI and carbon-based materials enhanced sensitivity toward amines has been observed. Successful fabrication of a low-power sensor with repeatable and reproducible responses with sensitivities up to 5 times higher than MOS sensors, together with response and recovery times in minutes was achieved. The excellent performance parameters make these flexible hybrid nanocomposite materials, attractive candidates for replacing conventional MOS sensors for low-power, real-time ammonia sensing applications.
Shahrzad Mahamadi from The University of Leeds presented work on sensing atomic-scale electric fields by self-organised lipid layers on Hg electrodes. It was shown that these layers allowed selective interactions with many pollutant chemicals and that modified the electrochemical properties of the Hg electrode and that cyclic voltammetry could allow detection and quantification of many pollutant species in trace quantities.
Kelly Whittingham from University of Lincoln exploited the Raman effect using silver colloid nanoparticles. This was used in a practical application to distinguish the dyes used in colouring different grades of diesel. It was shown that this method was sensitive and useful for discrimination of some of the dyes of interest such as Solvent Blue 14.
There was also an industrial presentation from Metrohm and showing extremely small nanostructured electrode arrays for electrochemical analyses.
There were two posters – one from Adam Davis, University of Birmingham and another from Nuria Castell-Balaguer, Norwegian Institute for Air Research. The former illustrated for nanosensors could be used to measure the pH of cloud droplets, while the latter showed results from an EU-funded project – CITSENSE that will seek to deploy mobile personal sensors to monitor urban air pollution.
The meeting, while small, was of high quality and allowed good interaction between the attendees. It reflected the state-of-the art in nanosensor-based technology and a large variety of possible applications of this emerging field.