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In this review, we describe the importance and possible electrochemical screening methods for the illicit drug – cocaine. It covers the detection at bare and modified solid electrodes, soft electrified junctions and nanopore sensing. Emphasis is given on interfacial modification techniques and electroanalytical parameters for cocaine detection in different environments, covering the detection from both, model and real samples. Image 1 • Electrochemistry can be used for selective cocaine sensing from real samples. • Selective detection of cocaine can be achieved with pristine carbon based electrodes. • Development of cocaine specific aptamer brought major development to the filed. • Soft and polarizable interphases are emerging sensing platforms for cocaine detection. • Little focus is given to electrochemically detect cocaine metabolites. [ABSTRACT FROM AUTHOR]

The behaviour of acid phosphatase at an electrified liquid–liquid interface was studied in this work. It was found that only the protonated form of the protein can undergo interfacial adsorption which is affected by the pH of the aqueous phase. With ion transfer voltammetry we could detect acid phosphatase in concentrations as low as 0.1 μM. We were able to co-deposit the protein and silica at the electrified liquid–liquid interface via controlled proton transfer to the organic phase where it catalyzed tetraethoxysilane hydrolysis, followed by polycondensation to silica. [ABSTRACT FROM AUTHOR]

• The behavior of three polyelectrolytes (PEI, PSS and PHMG) is studied at the ITIES. • Fiber glass membrane is modified with polyelectrolyte multilayer using LbL assembly. • Unmodified fiber glass membrane is used as a support of the ITIES. • Polyelectrolyte modified fiber glass membrane affect the ionic transport. In this work, the electrified liquid–liquid interface (LLI) was supported with the bare and polyelectrolyte modified fiberglass membranes. The permeability of these supports was then investigated with ion transfer voltammetry (ITV). This work descends from three mutually interconnected experimental tasks. (i) The study of an interfacial behavior of three polyelectrolytes, poly(ethyleneimine) (PEI), polystyrene sulfonate (PSS), and polyhexamethylene guanidine (PHMG) at the polarized LLI. (ii) Electrochemical characterization of the LLI supported by the unmodified fiberglass membrane. (iii) Polyelectrolyte multilayer placement, using layer-by-layer processing, at the surface of the fiberglass membrane and its further utilization as the support for the electrified LLI. Bare and modified membranes were characterized using ITV in the presence of a family of quaternary ammonium cations: tetramethylammonium (TMA+), tetraethylammonium (TEA+), tetrapropylammonium (TPrA+) and tetrabutylammonium (TBA+) initially dissolved in the aqueous phase as the chloride salts. The ionic currents related to their transmembrane transfer were affected already after the first polyelectrolyte layer placement. In addition to electrochemistry, the modification process was followed using several complementary techniques, including optical microscopy (OM), atomic force microscopy (AFM), infra-red (IR) spectroscopy, and scanning electron microscopy (SEM). The proposed methodology offers very simple, fast, and versatile (having in mind the available selection of functional polyelectrolytes) protocol for a membrane preparation having size sieving properties. In turn, the electrochemistry at the LLI can be used as an insightful tool to study the ionic transmembrane currents. Image, graphical abstract [ABSTRACT FROM AUTHOR]

• SiO 2 formation at the liquid – liquid interface is controlled electrochemically. • Addition of TEOS to the organic phase shrinks the potential window. • The interfacial behavior of proteins with TEOS in the organic phase is reported. • Proteins and SiO 2 can be simultaneously deposited at the ITIES. In this work, we have simultaneously examined, electrochemically driven deposition of three proteins (haemoglobin, acid phosphatase, and α-amylase) and silica films at a polarized liquid–liquid interface. The interfacial adsorption of the proteins occurs efficiently within the acidic pH range (pH = 2–4). The interfacial charge transfer reactions recorded in the presence of fully positivity charged macromolecules were followed with cyclic voltammetry on the positive side of the potential window. Faradaic currents attributed to the presence of proteins in the aqueous phase appeared for concentrations equal to ca. 0.1 µM for haemoglobin and acid phosphatase and ca. 1 µM for the α-amylase. Concomitant deposition of silica films was achieved via the addition of tetraethoxysilane molecules to the organic phase (1,2-dichloroethane). The hydrolysis and condensation reactions of tetraethoxysilane were controlled via the interfacial transfer of H+ coinciding with the potential for protein adsorption. The effect of tetraethoxysilane concentration – up to 50% by volume – revealed significant shrinkage of the potential window (the region where capacitive currents are recorded). The optimized platform was then used to prepare silica-proteins co-deposits. These could be easily collected from the interface and further analyzed with infrared spectroscopy and transmission electron microscopy. [ABSTRACT FROM AUTHOR]