Aqueous UV–VIS spectroelectrochemical study of the voltammetric reduction of graphene oxide on screen-printed carbon electrodes

Two graphene oxide (GO) materials with different layer size and proportion of functional groups in the basal planes (hydroxyl and epoxy) and in the edges (carbonyl and carboxyl) were used to modify the surface of commercially available screen-printed electrodes. Cyclic voltammetry in 0.1 M KNO3 was evaluated as an easy to use electrochemical methodology to reduce GO attached to the surface of screen-printed electrodes (SPEs). A cathodic peak related to the reduction of GO was identified, and the peak potential was correlated to the difficulty to reduce GO to electrochemically reduced graphene oxide (ERGO) depending on the functional groups present in the basal plane and in the edges of the original GO monolayers. Time-resolved UV–VIS absorption spectroelectrochemistry in near-normal reflection mode on a screen-printed electrode is used for the very first time as an in situ characterization technique for real-time monitoring unambiguously the electrochemical reduction of graphene oxide.projects CTQ2014-55583-R and CTQ2014-61914-EXP funded by Ministerio de Economía y Competitivida

In-situ testing of innovative marine instrumentation for nutrients, heavy metals and pH in Kongsfjorden, Svalbard Islands

Marine ecosystems are integral part of fundamental environmental functions that support life on Earth like climate control, erosion prevention and absorption of carbon dioxide. Oceans contribute to economical activities too with the following prosperity, social welfare, and increase in life quality. Nevertheless, several marine environments also in the European framework show increasing challenges to tackle like the loss of biodiversity and habitats, pollution and impacts due to climate change. For Italy and for Europe a growing environmental interest and awareness in both the public and private sectors is combined with a common strategic goal to ensure sustainable development and the continuity of economic activities. In order to achieve this goal and to improve the competitiveness of Italy and the EU, new technologies and methods for monitoring the marine environment are required

Quantitative Raman spectroelectrochemistry using silver screen-printed electrodes

Surface enhanced Raman scattering (SERS) is a powerful technique based on the intensification of the Raman signal because of the interaction of a molecule with a nanostructured metal surface. Electrochemically roughened silver has been widely used as SERS substrate in the qualitative detection of analytes at the ultra-trace level. However, its potential for quantitative analysis has not been widely exploited yet. In this work, the combination of time-resolved Raman spectroelectrochemistry with silver screen-printed electrodes (SPE) is proposed as a novel methodology for the preparation of SERS substrates. The in situ activation of a SERS substrate is performed simultaneously with the analytical detection of a probe molecule, controlling the process related to the preparation of the substrate and performing the analytical measurement in real time. The results show the good performance of silver SPE as electrochemically-induced surface-enhanced Raman scattering substrates. Raman spectra were recorded at fairly low integration times (250 ms), obtaining useful spectroelectrochemical information of the processes occurring at the SPE surface with excellent time-resolution. By recording the microscopic surface images at different times during the experiment, we correlated the different data obtained: structural, optical and electrochemical. Finally, the in situ activation process was used to obtain a suitable in situ SERS signal for ferricyanide and tris(bipyridine)ruthenium (II) quantification. The detection of the analytes at concentrations of a few tens of nM was possible with a low integration time (2 s) and good precision, demonstrating the exceptional performance of the Raman spectroelectrochemical method and the possibility to use cost-effective screen-printed electrodes for applications where a high sensitivity is needed.Ministerio de Economía y Competitividad (CTQ2017-83935-R, CTQ2014-55583-R, TEC2014-51940-C2-2R, CTQ2015-71955-REDT) and Junta de Castilla y León (BU033-U16

Bioresponsive, Electroactive, and Inkjet-Printable Graphene-Based Inks

With the advent of flexible electronics, the old fashioned and conventional solid-state technology will be replaced by conductive inks combined with low-cost printing techniques. Graphene is an ideal candidate to produce conductive inks, due to its excellent conductivity and zero bandgap. The possibility to chemically modify graphene with active molecules opens up the field of responsive conductive inks. Herein, a bioresponsive, electroactive, and inkjet-printable graphene ink is presented. The ink is based on graphene chemically modified with selected enzymes and an electrochemical mediator, to transduce the products of the enzymatic reaction into an electron flow, proportional to the analyte concentration. A water-based formulation is engineered to be respectful with the enzymatic activity while matching the stringent requirements of inkjet printing. The efficient electrochemical performance of the ink, as well as a proof-of-concept application in biosensing, is demonstrated. The versatility of the system is demonstrated by modifying graphene with various oxidoreductases, obtaining inks with selectivity toward glucose, lactate, methanol, and ethanol

Mechanical polishing as an improved surface treatment for platinum screen-printed electrodes

The viability of mechanical polishing as a surface pre-treatment method for commercially available platinum screen-printed electrodes (SPEs) was investigated and compared to a range of other pre-treatment methods (UV-Ozone treatment, soaking in N,N-dimethylformamide, soaking and anodizing in aqueous NaOH solution, and ultrasonication in tetrahydrofuran). Conventional electrochemical activation of platinum SPEs in 0.5 M H2SO4 solution was ineffective for the removal of contaminants found to be passivating the screen-printed surfaces. However, mechanical polishing showed a significant improvement in hydrogen adsorption and in electrochemically active surface areas (probed by two different redox couples) due to the effective removal of surface contaminants. Results are also presented that suggest that SPEs are highly susceptible to degradation by strong acidic or caustic solutions, and could potentially lead to instability in long-term applications due to continual etching of the binding materials. The ability of SPEs to be polished effectively extends the reusability of these traditionally "single-use" devices

Reduced Graphene Oxide Electrolyte-Gated Transistor Immunosensor with Highly Selective Multiparametric Detection of Anti-Drug Antibodies

The advent of immunotherapies with biological drugs has revolutionized the treatment of cancers and auto-immune diseases. However, in some patients, the production of anti-drug antibodies (ADAs) hampers the drug efficacy. The concentration of ADAs is typically in the range of 1-10 pm; hence their immunodetection is challenging. ADAs toward Infliximab (IFX), a drug used to treat rheumatoid arthritis and other auto-immune diseases, are focussed. An ambipolar electrolyte-gated transistor (EGT) immunosensor is reported based on a reduced graphene oxide (rGO) channel and IFX bound to the gate electrode as the specific probe. The rGO-EGTs are easy to fabricate and exhibit low voltage operations (& LE; 0.3 V), a robust response within 15 min, and ultra-high sensitivity (10 am limit of detection). A multiparametric analysis of the whole rGO-EGT transfer curves based on the type-I generalized extreme value distribution is proposed. It is demonstrated that it allows to selectively quantify ADAs also in the co-presence of its antagonist tumor necrosis factor alpha (TNF-alpha), the natural circulating target of IFX

Field testing, validation and optimization report

The COMMON SENSE project has been designed and planned in order to meet the general and specific scientific and technical objectives mentioned in its Description of Work (page 77). As the overall strategy, the 11 work packages (WPs) of the work plan were grouped into 3 key phases: (1) RD basis for cost-effective sensor development , (2) Sensor development, sensor web platform and integration, and (3) Field testing. In the first two phases, partners involved in WP1 and WP2 have provided a general understanding and integrated basis for a cost effective sensors development. Within the following WPs 4 to 8 the new sensors were created and integrated into different identified platforms. During the third phase of field testing (WP9), partners have deployed precompetitive prototypes at chosen platforms (e.g. research vessels, oil platforms, buoys and submerged moorings, ocean racing yachts, drifting buoys). Starting from August 2015 (month 22; task 9.2), these platforms have allowed the partnership to test the adaptability and performance of the in-situ sensors and verify if the transmission of data is properly made, correcting deviations. In task 9.1 all stakeholders identified in WP2 have been contacted in order to agree upon a coordinated agenda for the field testing phase for each of the platforms. Field testing procedures (WP2) and deployment specificities, defined during sensor development in WPs 4 to 8, have been closely studied by all stakeholders involved in field testing activities in order for everyone to know their role, how to proceed and to provide themselves with the necessary material and equipment (e.g. transport of instruments). All this information have provided the basis for designing and coordinating field testing activities. Subsequently, the available new sensors have been tested since August 2015 till mid-October of the current year (2016) as part of task 9.2, following the indications defined in D9.1, such as the intercomparison of the new sensors with commercial ones, when possible. The availability of new sensors was quite different in time starting with the first tests in September and October 2015 on noise, nutrient and heavy metals sensors and closing with pCO2 in late September 2016. Sensors are technically fully described in the deliverables of WPs 3 to 8 and are here just mentioned where necessary. For further details, please consider those reports. Objectives and rationale The protocols prepared in D9.1 have been verified during the field testing activities of the innovative sensors on platforms. These can be summarized into 3 categories: (1) Research vessels (regular cruises); (2) Fixed platforms; (3) Ocean racing yachts. An exhaustive analysis of the different data obtained during field testing activities has been carried on in order to set possible optimization actions for prototypes design and performances. The data from each platform have been analyzed to verify limits and optimal installations or possible improvements. Finally a set of possible optimization actions has been defined. Data and observations collected during the course of field testing have been used to iteratively optimize the design and performance of the precompetitive prototypes

Analysis of relevant technical issues and deficiencies of the existing sensors and related initiatives currently set and working in marine environment. New generation technologies for cost-effective sensors

The last decade has seen significant growth in the field of sensor networks, which are currently collecting large amounts of environmental data. This data needs to be collected, processed, stored and made available for analysis and interpretation in a manner which is meaningful and accessible to end users and stakeholders with a range of requirements, including government agencies, environmental agencies, the research community, industry users and the public. The COMMONSENSE project aims to develop and provide cost-effective, multi-functional innovative sensors to perform reliable in-situ measurements in the marine environment. The sensors will be easily usable across several platforms, and will focus on key parameters including eutrophication, heavy metal contaminants, marine litter (microplastics) and underwater noise descriptors of the MSFD. The aims of Tasks 2.1 and 2.2 which comprise the work of this deliverable are: • To obtain a comprehensive understanding and an up-to-date state of the art of existing sensors. • To provide a working basis on “new generation” technologies in order to develop cost-effective sensors suitable for large-scale production. This deliverable will consist of an analysis of state-of-the-art solutions for the different sensors and data platforms related with COMMONSENSE project. An analysis of relevant technical issues and deficiencies of existing sensors and related initiatives currently set and working in marine environment will be performed. Existing solutions will be studied to determine the main limitations to be considered during novel sensor developments in further WP’s. Objectives & Rationale The objectives of deliverable 2.1 are: • To create a solid and robust basis for finding cheaper and innovative ways of gathering data. This is preparatory for the activities in other WPs: for WP4 (Transversal Sensor development and Sensor Integration), for WP(5-8) (Novel Sensors) to develop cost-effective sensors suitable for large-scale production, reducing costs of data collection (compared to commercially available sensors), increasing data access availability for WP9 (Field testing) when the deployment of new sensors will be drawn and then realized