The conventional analytical methodology to detect chemical pollutants in marine ecosystems implies a certain rigidity in the process, since the samples are collected in situ but must be transported to laboratories on land for analysis. This procedure only allows information at fixed times and errors can arise in the stabilization and conservation of samples, in addition to the fact that it works with centralized instrumentation with high acquisition and maintenance costs and highly qualified technical personnel. In contrast to this methodology, what has recently emerged is what has been called the miniaturization of analytical systems with more robust and transportable designs, which allow the monitoring of the different chemical parameters of interest on site and in real time. One of these proposals is being designed by the QA2 group (Environmental Analytical Chemistry and Toxicology), belonging to the Department of Analytical and Food Chemistry, integrated into the Marine Research Center of the University of Vigo, and coordinated by researcher Carlos Bendicho within the framework of the project Innovative analytical systems based on nanostructured receptors on (nano)cellulosic substrates for the detection of substances of environmental interest. The study, selected within the Call for Research Challenges of the Ministry of Science, Innovation, has a four-year duration and is based on the use of cellulose substrates as a material for the design and construction of new sensors (paper-based analytical devices or PADs).
These disposable sensors can be used wherever required, that is, outside centralized laboratories, and in situations where there is a limitation of economic resources, thus allowing the democratization of the detection of substances of interest and making it possible in different socio-economic contexts. “Portability, rapid response and low cost play a preponderant role here. Ultimately, this type of sensor can contribute to a better assessment of exposure risks and facilitate more effective decision-making”, explains Professor Carlos Bendicho. Added to these advantages is the fact that they contribute to reducing the consumption of sample, reagents, and ultimately, energy, in line with current trends in green or sustainable chemistry.
The need for on-site analyses
The team of researchers from the QA2 group, co-financed under the FEDER/ESF Galicia 2014-2020 Operational Programme, explains that most instrumental systems used in laboratories are not suitable, for example, for use in the environment of an oceanographic ship, due to operating conditions (need for gases), energy requirements, fragility, instrumental complexity (space), as well as sensitivity to movements, vibrations, etc. For this reason, the researchers consider it necessary to have adequate tools that allow the concentration of chemical pollutants in the atmosphere, water, soils and sediments, etc. to be monitored quickly and effectively. However, they emphasize that the project does not aim to replace centralized analytical instrumentation but to complement it, “emphasizing advantageous aspects such as the ability to perform on-site analysis, routine control that allows large geographical areas to be monitored in a simple way and the involvement of citizens in more effective protection of the environment and health”.
Advantages over other sensors
The operation of these new PAD sensors is based on the immobilization of receptors (plasmonic nanoparticles, fluorescent carbon quantum dots, organic chromophores, etc.) as a basis for the selective recognition of substances and their integration into a microseparation device is carried out to achieve sensitivity and selectivity. As Bendicho points out, “unlike sensors built with other substrates such as plastic polymers, the interest of PADs lies in their hydrophilic nature, ease of manufacture, low cost, disposable use and biodegradability”. The project is also being developed in collaboration with researchers from other European countries in the context of the European action COST program (European network for the promotion of portable, affordable and simple analytical platforms).
In the environmental field, PADs can facilitate measurements in remote locations and study the temporal and spatial distribution of various pollutants in order to efficiently determine their sources, distribution and environmental impact. The developed PADs can have practical applications in studies of pollution of aquatic ecosystems (rivers, lakes, groundwater), marine environment (rias and estuaries on the Galician coast), studies of pollution sources produced by industry, oceanographic ships, mining operations near riverbeds, mobilization of pollutants due to forest fires, etc.
Multiple platforms
No marco do proxecto xa se deseñaron varias plataformas de celulosa para a detección de arsénico, boro, mercurio, ioduro, nitrito e sulfuro en varios tipos de augas, incluíndo auga de mar. A detección no PAD realízase finalmente a través de medidas colorimétricas ou fluorescentes, levando a cabo primeiro a dixitalización da imaxe mediante dispositivos das tecnoloxías da información e as comunicación (TICs) como escáneres de man, cámaras de móbil ou tablet, e posteriormente procesando o sinal mediante software (por exemplo, o software de dominio público ImageJ).
Source: DUVI
