Bionanotechnology applied to the problem of heavy metals in plants

Y. Reyes, E. González
Pontificia Universidad Javeriana,

Keywords: bionanotechnology, heavy metals, cadmium, basil


The incorporation of heavy metals in water, air, and soil is configured as one of the most important environmental sustainability problems. This incorporation produces a serious problem of bioaccumulation in the environment and serious health problems due, among other factors, to the increasing exposure caused by contaminated food consumption, inhalation of air with the presence of these pollutants [1]–[3]. In many countries of the world, the presence of heavy metals like arsenic, mercury, lead, and cadmium has been reported in vegetables and other food for human consumption. Studies conducted in China, India, Australia, among others, have reported the accumulation of heavy metals in the leaves of vegetables that have been exposed to fertilizers containing traces of Cd, Pb, Hg among others. In addition, they have identified the toxicity of heavy metals in the consumption of vegetables, cereals, and milk [4], [5]. Due to this delicate problem of contamination, the World Health Organization (WHO) and some environmental authorities have established permitted levels of metal concentration in drinking water, fish and some leafy vegetables. However, the measure is inefficient because not all types of food are taken into account, for example, plants that are consumed in fresh weight [6]. The conventional protocols used for chemical analysis of environmental samples in terms of detection of heavy metals (spectrometry, electroanalytical, and chromatographic methods) present limitations of cost, portability, measurement times and pretreatment of samples [7]–[9]. These operational and cost difficulties have motivated the development of new technologies to facilitate monitoring in situ measurement of different elements in water, soil, air and plants [9]–[13]. Biosensors are an excellent alternative to the problem of heavy metal pollution because they have characteristics of portability, sensitivity, reproducibility, and selectivity. In addition, they implement the use of nanomaterials for transduction signals due to their physicochemical properties, versatility in the design, and architecture of the biosensor [14]. Some authors have reported the optical, electrochemical, and nanomechanical biosensors for monitoring and detecting mercury, arsenic, and lead in water and soils. In this work, we present the design and development of a fluorescence-based bionanosensor for cadmium detection in basil plants. In order to configure the sensor, a careful bioaccumulation study of Cadmium was carried out in the roots, stems and leaves of four different plants (basil (Ocimum basillicum), mint (Mentha spicata), carrot (Daucus carota) and spinach (Spinacea oleracea)). Furthermore, HNCum was used as fluorophore and selective ligand of the Cd2+ cation, since it was at the root where the highest accumulation of cadmium was detected. The sensor bases its mode of operation of a cross-section made of a portion of the basil root under examination. In resume, the use of biosensors will allow us to gather information, develop monitoring strategies, obtain records of the presence of contaminants in plants and establish levels of risk and impact on living beings and the environment over the next years.