María Luz Rodríguez-Méndez

• PhD in Chemistry
• Professor (Full) at University of Valladolid

The electronic tongue (ET) and bioelectronic tongue (bioET) technologies have emerged as innovative and promising tools for the characterization and quality control of complex liquid matrices such as grape musts and wines. These multisensor systems, based on electrochemical detection and chemometric analysis, provide global and rapid information ab...

BACKGROUND Electronic tongues have been widely used to analyze wines. However, owing to the complexity of the matrix, the problem is not completely solved and further improvements are required. RESULTS A high‐performance potentiometric bioelectronic tongue (bio‐ET) specifically devoted to the assessment of wine components is presented. The novelty...

Improving the performance of thin film-based devices is a crucial factor for their successful application, mainly for organic electronic semiconductors. The adjustment of supramolecular structuring of thin films plays a role in the optical and electrical properties. In this sense, we investigated how various pH values, such as 2.5, 6.0, and 9.0, of...

An alternative approach to analyze complex matrixes such as milks lies on multivariate description of the chemical composition of samples where non-specific fingerprints are analyzed using data mining methods. Portable electronic tongues (ET) are of great interest for the dairy industry [1]. However, still several problems related to the fouling of...

In this work, an impedimetric bioelectronic tongue (bioET) formed by an array of interdigitated microelectrodes sensors was developed and applied in the discrimination of chemical components usually found in milk samples. Few studies of impedimetric bioETs applied in the dairy industry can be found in the bibliography due to the complexity of the c...

In the last years electronic tongues (ET) based on electrochemical sensors coupled to a pattern recognition system, have been developed and applied to the analysis of a variety of foods [1]. Nowadays it is evident that improvements in the field involve the development of instruments dedicated to a specific application. This requires the search of s...

This research investigates the impact of heat treatment on the microstructure, hardness, and corrosion resistance of 17-4 PH SS (stainless steel) processed by Selective Laser Manufacturing (SLM) in Phosphate Buffer Solution (PBS) and compared to its commercial wrought counterparts. The SLM process produced a segregated microstructure with significa...

Feeding the world’s increasing inhabitants requires considerable quantities of food, whose quality is essential to personal and economic health. Food quality parameters are mandatory to control throughout the fresh produce supply chain to meet consumer requests. Until now, different analytical techniques have been employed in food safety control. H...

The excellent catalytic properties of copper nano-particles (CuNPs) for the degradation of the highly toxic and recalcitrant chlorpyrifos pesticide are widely known. However, CuNPs generally present low stability caused by their high sensitivity to oxidation, which leads to a change of the catalytic response over time. In the current work, the immo...

Bioelectronic tongues (bioET) made of sensors combining enzymes and nanomaterials have been shown to be advantageous due to the specificity offered by the biosensors and the enhanced sensitivity provided by the nanomaterials. In this work, an innovative bioET for milk analysis is developed using potentiometric biosensors based on lactic dehydrogena...

A lab-made electronic nose (Enose) with vacuum sampling and a sensor array, comprising nine metal oxide semiconductor Figaro gas sensors, was tested for the quantitative analysis of vapor–liquid equilibrium, described by Henry’s law, of aqueous solutions of organic compounds: three alcohols (i.e., methanol, ethanol, and propanol) or three chemical...

The 17–4 Precipitation Hardening Stainless Steel (PH SS) manufactured by Selective Laser Melting (SLM) has wide application perspectives, but they are limited due to defects and anisotropy. The selection of the appropriate process variables plays a fundamental part in the microstructure and in the determination of the final mechanical and corrosion...

Recent advances in the field of electronic tongues (ET) are linked to the development of devices dedicated to a particular application. Following this idea, we have developed a voltammetric bioelectronic tongue (bioET) specifically dedicated to analyze milk. The performance of the multisensor system has been improved by incorporating biosensors com...

A portable potentiometric electronic tongue (PE-tongue) was developed and applied to evaluate the quality of milk with different fat content (skimmed, semi-skimmed, and whole) and with different nutritional content (classic, calcium-enriched, lactose-free, folic acid–enriched, and enriched in sterols of vegetal origin). The system consisted of a si...

The integration of silver nanomaterials as electron mediators in electrochemical biosensors can be crucial to improve the affinity with biomolecules and the electrochemical response. In this work, two voltammetric bioelectronics tongues (bioET) formed by biosensors based on the combination of enzymes with silver nanoparticles (AgNPs) (bioET-1) or s...

The objective of this work was to create an all-solid-state potentiometric bioelectronic tongue with an array of polymeric membrane-based sensors, which could then be used in the dairy sector. Membranes were modified with gold nanoparticles, and enzymes were covalently linked to the sensor’s surface to create an array of sensors with greater sensit...

The search of new biosensing platforms is crucial to improve the performance of electrochemical biosensors. In this work, Layer by Layer films containing combinations of materials with different functionalities were used to design electrochemical biosensor platforms for phenols detection [1-3]. Catechol and hydroquinone biosensors were obtained by...

Medical implants manufactured using biomaterial Ti-6Al-4V exhibit some disadvantages. Its higher elastic modulus than that of natural bone can cause stress shielding problems. This can be avoided using Ti-6Al-4V with pores in the implant structure. However, poor corrosion and tribocorrosion behaviors are yielded because of the large area exposed to...

The integration of nanomaterials as electron mediators in electrochemical biosensors is taking on an essential role. Due to their high surface-to-volume ratio and high conductivity, metallic nanowires are an interesting option. In this paper, silver nanowires (AgNWs) were exploited to design a novel catechol electrochemical biosensor, and the benef...

A strategy for the corrosion protection of porous materials using conductive polymers and nanocomposites of polymers and nanoparticle is presented. Several conductive polymers, various dopants and different electropolymerization conditions are studied to select the films with the highest corrosion resistance on porous and non-porous materials. It i...

Ti-6Al-4V alloy obtained by powder metallurgy (PM) is a good candidate biomaterial in the manufacture of dental implants but its inherent porosity makes it have worse corrosion behavior than conventionally obtained alloys. In order to improve the corrosion and biological properties, surface modification technologies could be used. The plasma electr...

A new and straightforward route to produce polymeric hollow microfibers is proposed. Polycaprolactone (PCL) hollow fibers are obtained for the first time by an environmentally friendly gas dissolution foaming approach, overcoming its limitations to induce porosity on samples on the micrometric range. Different porous morphologies are achieved from...

A bio-electronic tongue has been developed to evaluate the phenolic content of grape residues (seeds and skins) in a fast and easy way with industrial use in mind. A voltammetric electronic tongue has been designed based on carbon resin electrodes modified with tyrosinase combined with electron mediators. The presence of the phenoloxydase promotes...

Phenolic compounds such as catechol are present in a wide variety of foods and beverages; they are of great importance due to their antioxidant properties. Their consumption protects against the development of certain diseases such as cancer and cardiovascular diseases. A MIP chitosan (CS) film has been electrodeposited on a boron doped diamond (BD...

An enzymatic electrochemical biosensor for catechol detection based on silver nanowires (AgNWs), has been developed. The employment of AgNWs was essential to improve the electron transfer in comparison with that offered by an ITO substrate. AgNWs’ electrocatalytic properties and high affinity with biomolecules make them desirable for constructing b...

The search of new biosensing platforms is crucial to improve the performance of electrochemical biosensors. In this work, Layer by Layer films containing combinations of materials with different functionalities were used to design electrochemical biosensor platforms for phenols detection [1-3]. Catechol and hydroquinone biosensors were obtained by...

This research is based on the development of a novel, biocompatible and sensitive electrochemical imprinted sensor based on the detection of a phenolic compound, such as catechol, employing electroactive nanomaterials with the objective of improving the electron transfer between the electrode surface and the solution [1] and a natural biopolymer du...

Biosensor platforms consisting of layer by layer films combining materials with different functionalities have been developed and used to obtain improved catechol biosensors. Tyrosinase (Tyr) or laccase (Lac) were deposited onto LbL films formed by layers of a cationic linker (chitosan, CHI) alternating with layers of anionic electrocatalytic mater...

Microstructural changes that result in relevant improvements in mechanical properties and electrochemical behavior can be induced using different sintering conditions of ASTM F75 cobalt alloys during their processing using powder metallurgy technique. It has been observed that the increase in carbon and nitrogen content improves corrosion resistanc...

Phenolic compounds such as catechol are present in a wide variety of foods and beverages; they are of great importance due to their antioxidant properties. This research presents the development of a sensitive and biocompatible molecular imprinted sensor for the electrochemical detection of catechol, based on natural biopolymer-electroactive nanoco...

The performance of electrochemical laccase-based biosensors can be improved by immobilizing the enzyme on composite Layer-by-Layer (LbL) supports in which materials with complementary functions are combined. LbL films are formed by layers combining an electrocatalytic material which favors electron transfer (sulfonated copper phthalocyanine, CuPcS(...

Voltametric sensors formed by the combination of a sulfur-substituted zinc phthalocyanine (ZnPcRS) and gold nanoparticles capped with tetraoctylammonium bromide (AuNPtOcBr) have been developed. The influence of the nature of the interaction between both components in the response towards catechol has been evaluated. Electrodes modified with a mixtu...

The objective of this work was to develop a methodology based on multiparametric methods (FTIR and a voltammetric e–tongue based on SPE) to evaluate simultaneously fourteen parameters related to the phenolic content of red wines. Eight types of Spanish red wines, elaborated with different grape varieties from different regions and with different ag...

A bioelectronic tongue (bioET) based on combinations of enzymes (tyrosinase and glucose oxidase) and polypyrrole (Ppy) or polypyrrole/AuNP (Ppy/AuNP) composites was build up and applied to the analysis and discrimination of musts and wines. Voltammetric responses of the array of sensors demonstrated the effectiveness of polymers as electron mediato...

In this work, a method to improve the protection against corrosion of porous sintered stainless steel is presented. It is based on the electrodeposition of polypyrrole (PPy) layers doped with a large size counterion such as dodecylbenzenesulphonic acid (DBSA), a conducting polymer with high corrosion resistance and good biocompatibility. The effica...

The food industry requires the development of new sensors with improved performance in terms of sensitivity, detection limit and selectivity. Electrochemical sensors are an excellent choice because they fulfill these requirements with the advantage of their low cost and portability. A variety of voltammetric sensors has been used to analyze compone...

Herein, we report the in-situ synthesis and stabilization of protein modified gold nanoparticles without the use of activators in mild, near ambient conditions. The protein acted not only as a reducing agent of the gold salt precursor, but also as a stabilizing agent of the resulting gold nanoparticles. The protein/nanoparticle conjugates were coat...

This work focuses on studying natural rubber (NR) and epoxidized natural rubber (ENR) foams crosslinked at different absorbed doses and foamed using a chemical blowing agent. The aim is to study if the existence of epoxide groups within the natural rubber molecular structure influences the expansion capacity and the cellular structure morphology of...

An impedimetric electronic tongue to discriminate red wines with similar characteristics (same region, vintage and ageing method) is developed. The excellent performance achieved is due to the remarkable sensing properties of the nanocomposites forming the array and to the methodology developed to extract the input variables used in the statistical...

A nanostructured electrochemical bi-sensor system for the analysis of milks has been developed using the layer-by-layer technique. The non-enzymatic sensor [CHI+IL/CuPcS]2, is a layered material containing a negative film of the anionic sulfonated copper phthalocyanine (CuPcS) acting as electrocatalytic material, and a cationic layer containing a m...

A nanostructured electrochemical bi-sensor system for analysis of milks has been developed using the Layer by Layer technique. The non-enzymatic sensor [CHI+IL/CuPcS]2, is a layered material containing a negative film of the anionic sulfonated copper phthalocyanine (CuPcS) acting as electrocatalytic material, and a cationic layer containing a mixtu...

Porous electrodes based on polymethylmethacrylate and graphite foams (PMMA_G_F) have been developed and characterized. Such devices have been successfully used as voltammetric sensors to analyze catechol, hydroquinone, and their mixtures. The presence of pores induces important changes in the oxidation/reduction mechanism of catechol and hydroquino...

The maturity of grapes is usually monitored by means of the sugar concentration. However, the assessment of other parameters such as the phenolic content is also important because the phenolic maturity has an important impact on the organoleptic characteristics of wines. In this work, voltammetric sensors able to detect phenols in red grapes have b...

Gold nanoparticles (AuNPs) have been obtained using musts (freshly prepared grape juices where solid peels and seeds have been removed) as the reducing and capping agent. Transmission Electron Microscope images show that the formed AuNPs are spherical and their size increases with the amount of must used. The size of the AuNPs increases with the To...

In this work, an alternative method to monitor the phenolic maturity of grapes was developed. In this approach, the skins of grapes were used to cover the surface of carbon paste electrodes and the voltammetric signals obtained with the skin-modified sensors were used to obtain information about the phenolic content of the skins. These sensors coul...

Nickel can cause severe allergic reactions. Therefore, efforts are made to reduce the content of nickel in austenitic stainless steels (SS). Powder metallurgy (PM) techniques can produce this steel in a highly affordable way. A novel low-nickel highnitrogen austenitic powder metallurgy PM stainless steel is investigated in terms of corrosion behavi...

The electron mediator properties of three subphthalocyanines (SubPcs) [hexa-chloro boron subphthalocyanine (ClSubPc), tri-tert-butyl boron subphthalocyanine (t-BuSubPc) and hexa-phenoxy boron subphthalocyanine (PhOSubPc)] in Tyrosinase and Laccase biosensors (deposited on ITO glass) for the detection of catechol and hydroquinone were evidenced. A p...

Voltammetric sensors chemically modified with combinations of two electrocatalytic materials: tetraoctylammonium bromide capped gold nanoparticles (AuNPNBr) and a sulphur containing zinc phthalocyanine derivative (ZnPcRS) are reported. The electrocatalytic effects in the detection of catechol have been analyzed in sensors obtained by direct mixing...

Nickel-free austenitic powder metallurgy stainless steels were prepared and characterized. The main issue was to obtain potential biocompatible materials. Mechanical alloying in a nitrogen atmosphere was used to obtain these powders. The main factor to be controlled was the milling time. Powder metallurgy was the technique to obtain massive samples...

The most popular sensors in multisensor systems (electronic tongues) are voltammetric and potentiometric ones. Practical application of multisensor systems for evaluation of particular target parameters requires calibration step. Even if both types of sensors (voltammetric and potentiometric) can be sensitive towards the same parameter of an analyt...

The quality of wines is usually evaluated by traditional chemical analysis or by a sensory panel composed of trained experts. In recent years, a new class of instruments, the electronic tongues, have been successfully applied to the analysis of wines including quality control, aging control, or detection of fraudulences among others. The use of arr...

The sensing properties of electrodes chemically modified with PEDOT/PSS towards catechol and hydroquinone sensing have been successfully improved by combining layers of PEDOT/PSS with layers of a secondary electrocatalytic material such as gold nanoparticles (PEDOT/PSS/AuNPs), copper phthalocyanine (PEDOT/PSS/CuPc) or lutetium bisphthalocyanine (PE...

Obtaining high-density polyethylene-based microcellular foams is a topic of interest due to the synergistic properties that can be obtained by the fact of achieving a microcellular structure using a polymer with a high number of interesting properties. However, due to the high crystallinity of this polymer, the production of low-density microcellul...

A bioelectronic tongue based on nanostructured biosensors specific for the simultaneous detection of sugars and phenols has been developed. The array combined oxydases and dehydrogenases immobilized on a lipidic layer prepared using the Langmuir-Blodgett technique where Glucose oxidase, D-Fructose dehydrogenase, Tyrosinase or Laccase were imbibed....

The quality of wines is usually evaluated by a sensory panel formed of trained experts or traditional chemical analysis. Over the last few decades, electronic noses (e-noses) and electronic tongues have been developed to determine the quality of foods and beverages. They consist of arrays of sensors with cross-sensitivity, combined with pattern rec...

The capability of a phthalocyanine-based voltammetric electronic tongue to analyze strong alcoholic beverages has been evaluated and compared with the performance of spectroscopic techniques coupled to chemometrics. Nalewka Polish liqueurs prepared from five apple varieties have been used as a model of strong liqueurs. Principal Component Analysis...

Highly selective and sensitive modified electrodes have been the focus of many studies in sensing applications. Gene or enzymatic biosensors are greatly effective in this context, but they are often fragile and expensive. An alternative to these systems is the use of mimetic systems such as artificial enzyme immobilized in a matrix formed by thin f...

Arrays of phthalocyanine-based sensors with complementary activity have been used to develop voltammetric electronic tongues. Such systems have demonstrated to be useful in enology for the evaluation of quality of wines in different production stages, from grapes to bottles. In this paper, the state of the art of multisensor systems based on phthal...

In this study, a portable electronic tongue was developed and successfully used to distinguish and to discriminate quality of saffron samples. The proposed system consisted of an array of voltammetric sensors based on screenprinted electrodes (SPE), where the working electrodes were of different chemical natures (e.g. carbon, gold and modified carb...

Voltammetric sensors based on phthalocyanines have been used to detect a variety of compounds. In this paper, the state of the art of sensors prepared using classical techniques will be revised. Then, new strategies to improve the performance of the sensors will be described using as example sensors chemically modified with lutetium bisphthalocyani...

Electronic Nose and Tongue in Food Science describes the electronic products of advanced chemical and physical sciences combined with intuitive integration of microprocessors, advanced bioinformatics and statistics. These include, for example, voltammetric, bio-electronic, piezoelectric platforms made from a variety of components including, nanopar...

An array of electrochemical quartz crystal electrodes (EQCM) modified with nanostructured films based on phthalocyanines was developed and used to discriminate musts prepared from different varieties of grapes. Nanostructured films of iron, nickel and copper phthalocyanines were deposited on Pt/quartz crystals through the Layer by Layer technique b...

Two different methods were used to obtain polypyrrole/AuNP (Ppy/AuNP) composites. One through the electrooxidation of the pyrrole monomer in the presence of colloidal gold nanoparticles, referred to as trapping method (T), and the second one by electrodeposition of both components from one solution containing the monomer and a gold salt, referred t...

The presence of hydroquinone (HQ), a phenol ubiquitous in nature and widely used in industry, needs to be monitored because of its toxicity to the environment. Here we demonstrate efficient detection of HQ using simple, fast, and noninvasive electrochemical measurements on indium tin oxide (ITO) electrodes modified with nanoparticles comprising bim...

Austenitic, ferritic and duplex stainless steels obtained through powder metallurgy technology were sintered in vacuum. Powders were compacted at 650 or 750 MPa and sintered in vacuum with two sinter-cooling rates (furnace- and water-cooling). Mechanical properties, using tensile testing and hardness measurements were evaluated. A full microstructu...

There is a wide variety of Lager beer styles that differ, among others characteristics, in their alcohol content and color. Beer contains a high concentration of electrochemical active compounds, some of them related to the color of these beverages. In the present work, the applicability of a portable electronic tongue based on an array of electroc...

The use of quick, reliable and cheap sensors for the detection of chemical compounds represents an important need in the wine sector. Among the analytes that must be monitored and measured in order to guarantee the quality of final products and to verify that industrial processes are under control, glucose, phenolic compounds and acidity are the mo...

Electrochemical sensors have been prepared using a range of materials and using a variety of methods. The selection of phthalocyanines or nanoparticles as sensing materials in electrochemical sensors was inspired in their electrocatalytic properties ¹ . In turn, nanostructured sensors prepared using the Langmuir-Blodgett (LB) or the electrostatic L...

Arrays of voltammetric sensors and biosensors based on phthalocyanines have been developed and used to analyze wines and grapes. Nanostructured sensors prepared by the Langmuir-Blodgett (LB), Layer by Layer (LbL) or electrodeposition are superior because the high number of active sites. The LB and the LbL techniques can be used to co-deposit electr...

A synergistic electrocatalytic effect was observed in sensors where two electrocatalytic materials (functionalized gold nanoparticles and lutetium bisphthalocyanine) were co-deposited using the Langmuir-Blodgett technique. Films were prepared using a novel method where water soluble functionalised gold nanoparticles [(11-mercaptoundecyl)tetra(ethyl...

A chemically modified electrode consisting of Langmuir-Blodgett (LB) films of n-dodecanethiol functionalized gold nanoparticles (SDODAuNP-LB), was investigated as a voltammetric sensor of organic and phenolic acids of interest in the wine industry. The nanostructured films demonstrated interfacial properties being able to detect the main organic ac...