Abstract
Over the last decades, the interface between two immiscible electrolyte solutions (ITIES) attracted considerable attention of the scientific community due to their vast applications, such as extraction, catalysis, partition studies and sensing. The aim of this Review is to highlight the potential of electrochemistry at the ITIES for analytical purposes, focusing on ITIES-based sensors for detection and quantification of chemically and biologically relevant (bio)molecules. We start by addressing the evolution of ITIES in terms of number of publications over the years along with an overview of their main applications (Chapter 1). Then, we provide a general historical perspective about pioneer voltammetric studies at water/oil systems (Chapter 2). After that, we discuss the most impacting improvements on ITIES sensing systems from both perspectives, set-up design (interface stabilization and miniaturization, selection of the organic solvent, etc.) and optimization of experimental conditions to improve selectivity and sensitivity (Chapter 3). In Chapter 4, we discuss the analytical applications of ITIES for electrochemical sensing of several types of analytes, including drugs, pesticides, proteins, among others. Finally, we highlight the present achievements of ITIES as analytical tool and provide future challenges and perspectives for this technology (Chapter 5).

Abstract
Molecularly imprinted polymers (MIPs) are biomimetic materials of great interest in the scientific and industrial fields for the development of innovative sensing strategies. Herein, we proposed a new sensing application by developing an electrochemical sensor using molecular imprinting (MI) technology for recognition of atrial natriuretic peptide (ANP) both as a free molecule in solution and attached to nanoparticle-based drug delivery systems (DDSs), aiming to provide fast and reliable information on the cell uptake of nanoparticles (NPs). As proof of concept, poly(lactic-co-glycolic acid) (PLGA) NPs were synthesized and used as nanocarriers for ischemic heart disease therapy were synthesized and then functionalized with ANP (named here as PLGANPs@ANP). The MIP receptor film was prepared by electrochemical polymerization of dopamine over the working area of a gold screen-printed electrode (AuSPE), using cyclic voltammetry (CV) technique. The construction of the ANP sensor was carefully optimized to enhance its performance, including the film thickness and the procedures for effective template extraction from the MIP matrix. The MIP biosensor presented a linear response against polymeric NPs (PLGA-NPs@ANP) concentration logarithm ranging from 4.0 mu g mL(-1) to 100 mu g mL(-1), with a sensitivity of - 0.0129 mA mL mu g(-1) decade(-1) and an LOD < 4.0 g mL(-1). Furthermore, the developed MIP receptor film was able to discriminate ANP-functionalized nanocarriers from non-functionalized NPs.

Abstract
The field of electrochemistry at the interface between two immiscible electrolyte solutions (ITIES) has been continuously expanding over the years due to their vast number of applications, including to investigate the partitioning of ionizable drugs at liquid-liquid systems. The aim of this Review is to highlight the great potential of ITIES as simple model of biological membranes to gather information on drug partition, lipophilicity, and pharmacokinetics that can be very useful for researchers in the field of drug discovery for development of new drugs with enhanced permeability. Relevant contributions and perspectives to improve the applicability of ITIES in partition studies were highlighted and discussed. The second part of this Review pretends to highlight the application of electrochemistry at the ITIES as experimental technique to investigate interactions between small ligands, including drugs, and DNA, a topic of high research interest in pharmaceutical and biological sciences, which remains with lots of opportunities to explore. Voltammetry at Liquid-Liquid Interfaces can be a versatile tool in the field of Drug Discovery as simple model for mimicking drug permeation through biological membranes helping to understand the partition of ionizable drugs between the aqueous and organic phases while providing fundamental information on its lipophilicity that can contribute to the design of new drugs with improved biological activity. image

Abstract
Purpose Pejao Mining Complex locates in Castelo de Paiva municipality and, until its closure in 1994, was one of the most important coal mines in the Douro Coalfield. This work aims to study the presence, quantify, and evaluate the dissemination of mercury (Hg), a potentially toxic element (PTE) of major public health concern by the World Health Organization (WHO), from a waste pile affected by coal fires.Materials and methods Samples from areas affected and unaffected by the combustion and from surrounding soil were collected from Fojo waste pile region. First, the Hg pseudo-total concentration was estimated for all collected samples by soil microwave-assisted digestion with aqua regia (USEPA 3051A). Then, a sequential extraction procedure (SEP), the USEPA 3200, was applied for Hg fractionation and speciation aiming to evaluate Hg mobility and bioavailability to surrounding ecosystems.Results and discussion The results obtained showed a Hg enrichment in soil samples when compared to Portuguese and international reference values for soils. Relatively to the Hg availability and mobility, although it predominates in the semi-mobile fraction, the waste pile materials exposed to combustion showed a concerning increase of Hg levels in the mobile fraction that contains the more labile Hg species, being a major source of environmental contamination by Hg.Conclusions This study allowed to conclude that combustion of mining residues increased Hg mobility, toxicity, and bioavailability, increasing the contamination potential of the coal waste pile. The methodology applied in this work can be replicated in other abandoned mines to monitor, control, and/or mitigate the Hg environmental impact in the surrounding soils and waters.

Abstract
This work reports the development of a simple and rapid electrochemical immunosensor for the determination of breast cancer biomarker Cancer Antigen 15-3 (CA 15-3). Disposable and cost-effective chips, consisting of gold screen-printed electrodes (AuSPEs), were used to develop the portable electrochemical devices for monitoring the biomarker in point-of-care (PoC), under clinical context. The biosensor preparation consisted of two simple steps. First, a self-assembled monolayer (SAM) of mercaptosuccinic acid (MSA) was formed at the AuSPE surface. Then, the CA 15-3 antibody was covalently bound to the carboxylic groups standing at the electrode surface using EDC/NHS chemistry. The performance of the developed immunosensor was evaluated by assessing the sensor sensitivity, linear response interval, selectivity and detection limit (LOD). The developed immunosensor provided a wide linear concentration range (from 1.0 to 1000 U mL(-1)) and low detection levels were achieved (LOD of 0.95 U mL(-1)), enabling the sensitive detection of the cancer biomarker at clinically relevant levels, using square wave voltammetry (SWV) as electroanalytical technique. Moreover, selectivity studies performed against other cancer biomarkers (CA 125 and CA 19-9) revealed that the antibody has high selectivity for CA 15-3 antigen. The immunosensor was applied to the quantification of CA 15-3 in artificial serum samples with satisfactory results.

Abstract
The design and synthesis of artificial receptors based on molecular imprinting (MI) technology for the development of a new MIP-based biosensor for detection of the stress biomarker a-amylase in human saliva in point-of-care (PoC) applications is described in this work. The portable electrochemical devices for monitoring a-amylase consists of cost-effective and disposable gold screen-printed electrodes (AuSPEs). To build the electrochemical device, the template biomolecule was firstly immobilized directly over the working area of the gold chip previously activated with a self-assembled monolayer (SAM) of cysteamine (CA). Then, pyrrole (Py) monomer was selected as building block of a polymeric network prepared by CV electropolymerization. After the electropolymerization process, the enzyme was removed from the polymer film in order to build the specific recognition sites for the target enzyme. The MIP biosensor showed a very wide linear concentration range (between 3.0 × 10-4 to 0.60 mg mL-1 in buffer solution and between 3.0 × 10-4 to 3.0 × 10-2 mg mL-1 in human saliva) and low detection levels were achieved (LOD < 3.0 × 10-4 mg mL-1) using square wave voltammetry (SWV) as the electroanalytical technique.