Graphitizing screen printing

A. Ivanov, G. Evtugyn, L.V. Lukachova, E.E. Karyakina, HC. Budnikov, S.G. Kiseleva, A.V. Orlov, G.P. Karpacheva, and A.A. Karyakin, Cholinesterase potentiometric sensor based on graphite screen-printed electrode modified with processed polyaniline. IEEE Sensors J. 3, 333-340 (2003). 

Recently, Mascini s group has also used this method, in combination with disposable graphite screen-printed electrodes, initially for model DNA sequence detection [70] and more recently for the quantitation of human apolipoprotein E genotypes [71] in both cases, daunomycin was used as an indicator species. Daunomycin is a DNA intercalant bearing both quinone and hydroquinone functionalities, and Mascini s group used constant-current oxidation of the hydroquinone moiety for detection. Their detection limit of 1 pg mL target DNA resulted in the need for PCR amplification prior to DNA detection. 

Uses a new and/or re-used graphite screen-printed electrode modified with silver hexacyanoferrate and a Nafion polymer layer... 

Moreover, disposable electrochemical sensors for the detection of a specific sequence of DNA were realised by immobilising synthetic single-stranded oligonucleotides onto a graphite or a gold screen-printed electrode. Tire probes became hybridised with different concentrations of complementary sequences present in the sample. 

FIGURE 6-23 Steps involved in the screen-printing process (a) deposit the graphite suspension onto the screen (b) load the screen mesh with the graphite (c) force the graphite onto the substrate. (Reproduced with permission from reference 83.)... 

The influence of porosity on the electrochemical activity has not been studied much for electrolyte-supported cells because anode pastes for electrolyte-supported cells are made for screen printing, and thus contain significant amounts of organics, which almost guarantees sufficient porosity. In addition, since the anode thickness for electrolyte-supported cells is only on the order of 50 pm, the concentration polarization itself becomes much less of an issue. In fact, Jiang et al. [44] showed that anode overpotential for cermet anodes prepared with extra graphite pore formers... 

Screen printing Metals, carbon/graphite, semiconductors, insulators Apply liquid solution or suspension through fine mesh screen mask to form pattern then convert film to desired form as above... 

Carbon films and graphite films have been prepared by vacuum evaporation [28,42,76,77], pyrolysis [29,36,78-83], screen printing [46,62,63,65,66,84], and laser photoactivation of sites on a graphite or glassy carbon substrate [85]. Various pyrolytic processes have been successful, most based on the deposition of volatile precursor compounds. For example, methane can be pyrolyzed while... 

The possible use of graphite-epoxy material by screen-printing technology opens the possibility of mass production of disposable sensors for heavy-metal analysis using stripping techniques. The utilization of these sensors for an extensive application in real heavy-metal samples is underway in our laboratories. 

Carsol and Mascini [87] if-value Fish Two reactors in series one packed with nucleoside phosphorylase (Np) and the other with xanthine oxidase (XO)/immobilised on aminopropyl glass Screen-printed graphite electrode/450 mV vs. Ag/ AgCl ... 

Fig. 16.3. Cyclic voltammogram of 13.6 U PP2A from Upstate (blank) and 0.3 mM catechol monophosphate+13.6 U PP2A from Upstate (CMP+PP) at lOOrnVs-1 using a single-drop configuration on a horizontally supported screen-printed two-electrode system, with graphite as working and Ag/AgCl as reference/auxiliary electrode. Reprinted from Campas et al. [86], with permission from Elsevier.

A. Avramescu, S. Andreescu, T. Noguer, C. Bala, D. Andreescu and J.-L. Marty, Biosensors designed for environmental and food quality control based on screen-printed graphite electrodes with different configurations, Anal. Bioanal. Chem., 374 (2002) 25-32. 

Stability of Prussian blue modified screen-printed electrodes The operational stability of all the PB-modified sensors is a critical point, especially at neutral and alkaline pH. A possible explanation for reduced stability could be the presence of hydroxyl ions at the electrode surface as a product of the H202 reduction. Hydroxyl ions are known to be able to break the Fe-CN-Fe bond, hence solubilising the PB [21]. An increased stability of PB at alkaline pH was first observed by our group after adopting a chemical deposition method for the modification of graphite particles with PB for the assembling of carbon paste electrodes [48]. 

In the traditional format, screen-printed electrodes are used as solid phase to carry out the immunoassay and as signal transducers. In recent years, different kinds of beads (glass, graphite particles or magnetic particles) have been used as solid phase to perform the immunoassay. For this reason, it is possible to use a new approach in the immunosensor construction coupling beads to screen-printed electrodes. 

Our work deals with only a few examples (i) the immunosensor for the forest-spring encephalitis diagnosis (a metal label is used for signal generation), (ii) the enzyme-free urea sensor and (iii) the platinum sensor for antioxidant activity determination. What they all have in common is a screen-printed transducer consisting of graphite or Pt nanoparticles. Transducer configuration is shown in Fig. 27.1. 

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