Monitoring water quality has become a goal to prevent issues related to human health and environmental conditions. In this sense, the concentration of metal ions in water sources is screened, as these are considered persistent contaminants. In this work, we describe the implementation of customized graphite electrodes decorated with two types of Hg nanoparticles (Hg-NPs), optimized toward the electrochemical detection of Cd, Pb and Cu. Here, we combine Hg, a well-known property to form alloys with other metals, with the nanoscale features of Hg-NPs, resulting in improved electrochemical sensors towards these analytes with a substantial reduction in the used Hg amount. Hg-NPs were synthesized using poly(diallyldimethylammonium) chloride (PDDA) in a combined role as a reducing and stabilizing agent, and then appropriately characterized by means of Transmission Electron Microscopy (TEM) and Zeta Potential. The surface of composite electrodes with optimized graphite content was modified by the drop-casting of the prepared Hg-NPs. The obtained nanocomposite electrodes were morphologically characterized by Scanning Electron Microscopy (SEM), and electrochemically by Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS). The results show that the Hg-NP-modified electrodes present better responses towards Cd(II), Pb(II) and Cu(II) detection in comparison with the bare graphite electrode. Analytical performance of sensors was evaluated by square-wave anodic stripping voltammetry (SWASV), obtaining a linear range of 0.005–0.5 mg·L−1 for Cd2+, of 0.028–0.37 mg·L−1 for Pb2+ and of 0.057–1.1 mg·L−1 for Cu2+. Real samples were analyzed using SWASV, showing good agreement with the recovery values of inductively coupled plasma–mass spectrometry (ICP-MS) measurements.

The design of compartments capable of carrying out biological reactions in a local space has provoked enormous interest by providing spatiotemporal and long‐term selective control of biological activity. On the other hand, the application of metal‐porphyrins in the field of biomedical science as nanozymes is gaining substantial importance. Porphyrins are the most widely studied tetrapyrrole‐based compounds because of their important roles in vital biological processes and they possess peculiar photochemical, photophysical, and photo/redox properties. Herein, we demonstrate the use of pH‐responsive and photo‐crosslinked polymersomes for loading β‐cyclodextrin‐Hemin complexes as potential peroxidase‐mimicking cavity. The loading of catalytic active centers into polymeric vesicles represents a simple and effective strategy for enzyme mimicry. Physicochemical and enzyme‐like properties are studied using a variety of characterization methods at different simulated microenvironments. This work offers an improvement of the aqueous solubility of the Hemin molecule, crucial for biomedical applications. In addition, these nanocompartments can be used as artificial radical‐producing and hydrogen peroxide‐consuming organelles, being able to replace cell functions in different microenvironments. Therefore, these artificial organelles, entrapping nanozymes, could provide promising synergistic and more personalized therapies on demand in modern nanomedicine.

Many carbon materials are well-known conductive materials, widely used in the fabrication of composite electrodes. In this work, diverse allotropic forms of carbon such as graphite, MWCNTs and rGO were tested. Furthermore, these materials allow the construction of cheaper, smaller, portable, reliable and easy-to-use devices, which can be easily modified. The above-mentioned composite electrodes were developed for metal analysis in water such as Cu, Cd and Pb that, at a high concentration, can have consequences on human health. SWASV is the selected technique. It would be ideal to exploit the potential properties of mercury for metal detection by tuning the electrode’s surface. Due to mercury’s hazardous properties and to reduce the amount of this substance used in polarography, the use of nanoparticles is a good option due to their properties. Mercury nanoparticles were used to modify the surface of the composite electrodes to improve electroanalytical sensor response. For this reason, using these modified composite electrodes can lower detection limits and widen the linear range that can be achieved for Cd (0.05–1 mg·L−1) and Pb (0.045–1 mg·L−1). However, for Cu (0.114–1.14 mg·L−1), meaningful variations were not observed compared to the bare electrode.