Nuestros investigadores

Sergio Arana Alonso

Publicaciones científicas más recientes (desde 2010)

Autores: Hisey, C. L.; Martínez, Miguel; et al.
ISSN 1932-1058  Vol. 13  Nº 044105   2019 
Highly migratory cancer cells often lead to metastasis and recurrence and are responsible for the high mortality rates in many cancers despite aggressive treatment. Recently, the migratory behavior of patient-derived glioblastoma multiforme cells on microtracks has shown potential in predicting the likelihood of recurrence, while at the same time, antimetastasis drugs have been developed which require simple yet relevant high-throughput screening systems. However, robust in vitro platforms which can reliably seed single cells and measure their migration while mimicking the physiological tumor microenvironment have not been demonstrated. In this study, we demonstrate a microfluidic device which hydrodynamically seeds single cancer cells onto stamped or femtosecond laser ablated polystyrene microtracks, promoting 1D migratory behavior due to the cells' tendency to follow topographical cues. Using time-lapse microscopy, we found that single U87 glioblastoma multiforme cells migrated more slowly on laser ablated microtracks compared to stamped microtracks of equal width and spacing (p < 0.05) and exhibited greater directional persistence on both 1D patterns compared to flat polystyrene (p < 0.05). Single-cell morphologies also differed significantly between flat and 1D patterns, with cells on 1D substrates exhibiting higher aspect ratios and less circularity (p < 0.05). This microfluidic platform could lead to automated quantification of single-cell migratory behavior due to the high predictability of hydrodynamic seeding and guided 1D migration, an important step to realizing the potential of microfluidic migration assays for drug screening and individualized medicine. Published under license by AIP Publishing.
Autores: Zabalo, J.; Arana, Sergio; et al.
ISSN 0956-5663  Vol. 123  2019  págs. 237 - 243
Development of new targeted therapies is a challenge in the battle against cancer. Although a variety of treatments is currently available, there is no technique for rapidly evaluating the response of cancer patients to the drug. In this work, a microfluidic platform for the real-time simultaneous analysis of the success rate of different nanoparticle based chemotherapeutic drugs is presented. Based on a previous planar chamber and a reported sensitivity enhancing strategy, linear and cross shape microstructures were integrated into the chamber dome of the microfluidic polydimethylsiloxane and glass platform in order to provide a higher fluid mixing and treatment-cell interaction. Several methotrexate (MTX) based treatments (free MTX, MTX loaded Lecithin-PVA nanoparticles, MTX loaded Lecithin-Tween 80 nanoparticles) as well as their respective controls (cell media and both blank nanoparticles) were recirculated through the microchamber over an osteosarcoma cell monolayer. These nanovehicles reduced cell population to less than 20% (LEC-PVA nanoparticles) and 2.3% (LEC-Tween nanoparticles), demonstrating that nanoparticles are a promising target therapy for cancer treatment. Moreover, microstructured platforms demonstrated a higher efficacy in the drug-screening process: due to the liquid folding a higher amount of nanoparticles was internalized by the cells and, therefore, results were observed faster. In fact, the time required to reduce cell viability to the half was nearly a 75% faster. Furthermore, this microfluidic platform offers the capability to test up to five different drugs simultaneously, making it a powerful tool to evaluate the effect of multiple drugs and determine the most effective and personalized treatment.
Autores: Tubia, Imanol, (Autor de correspondencia); Prasad, K.; Pérez, Eva ; et al.
ISSN 0168-1605  Vol. 283  2018  págs. 65 - 76
Spoilage yeasts detection is the key to improve the quality of alcoholic fermentation beverages such as wine and cider. The metabolic activity of the spoilage yeast causes irreparable damage to many liters of final products every year. Therefore, winemakers and cider-house companies suffer a substantial economic impact. Thus, over the years, many detection techniques have been proposed to control the occurrence of spoilage yeast. Out of the many spoilage yeast genera, Brettanomyces is one of the most commonly encountered in the beverage industry. Leveraging its ability to thrive in wine and cider conditions (low pH, high levels of ethanol, and low oxygenation levels), Brettanomyces can proliferate inside beverage production tanks. Moreover, their resultant by products reduce the quality of the beverage. While the beverage industry has made great strides in detecting harmful organisms, gaps remain. Traditional methods such as microscopy, cell plating, gas chromatography-mass spectrometry, etc. are often imprecise, expensive, and/or complicated. New emerging spoilage yeast detection platforms, such as biosensors and microfluidic devices, aim to alleviate these constraints. Novel platforms have already demonstrated great promise to be a real alternative for in situ and fast detection in the beverage industry. Finally, the review discusses the potential of emerging spoilage yeast detection and treatment methods.
Autores: Tubia, Imanol, (Autor de correspondencia); Paredes, J; Pérez, Eva ; et al.
ISSN 0924-4247  Vol. 269  2018  págs. 175 - 181
Brettanomyces bruxellensis is considered one of the most relevant spoilage yeasts in the production of alcoholic beverages, especially for wine and cider. During fermentation and later storage, these yeasts can cause changes in the characteristics of the product, ruining the aroma and taste. The presence of Brettanomyces causes a decrease in the quality of the final products and important economic losses. The current work presents a detection method based on impedance spectroscopy analysis using label-free interdigitated microelectrode (IDE) based sensors for spoilage yeast detection. Different conditions (static and stirring) were tested in Brettanomyces cultures inside reactors in order to evaluate the growth behavior. Our results indicate a faster response and an 8% increase of the relative variation of the impedance under stirring condition due to biofilm formation onto the surface of the sensors. Equivalent circuit analysis also confirmed that the difference was caused by the larger biofilm formation under dynamic conditions. The results suggest that this technology could be applied for the early detection of spoilage yeast in wine and cider industries, providing more efficient methods to achieve a higher quality of the final products. (C) 2017 Elsevier B.V. All rights reserved.
Autores: Tubia, Imanol; Paredes, J; Pérez, Eva ; et al.
ISSN 0956-5663  Vol. 102  2018  págs. 432 - 438
Brettanomyces is a yeast species responsible for wine and cider spoilage, producing volatile phenols that result in off-odors and loss of fruity sensorial qualities. Current commercial detection methods for these spoilage species are liable to frequent false positives, long culture times and fungal contamination. In this work, an interdigitated (IDE) biosensor was created to detect Brettanomyces using immunological reactions and impedance spectroscopy analysis. To promote efficient antibody immobilization on the electrodes¿ surface and to decrease non-specific adsorption, a Self-Assembled Monolayer (SAM) was developed. An impedance spectroscopy analysis, over four yeast strains, confirmed our device's increased efficacy. Compared to label-free sensors, antibody biosensors showed a higher relative impedance. The results also suggested that these biosensors could be a promising method to monitor some spoilage yeasts, offering an efficient alternative to the laborious and expensive traditional methods.
Autores: Tubia, Imanol, (Autor de correspondencia); Apezteguia, A.; et al.
ISSN 0924-4247  Vol. 277  2018  págs. 1 - 7
Impedance spectroscopy analysis (IS) has awakened a great interest for many industrial applications and sectors for the implementation of novel monitoring capabilities. More specifically, microelectrode-based sensors are increasingly being used to analyze electrical or electrochemical changes in liquid samples, as well as other effects such as biofouling, particle adhesion, etc. However, real environmental conditions are usually subjected physiochemical changes that affect the impedance measurement. In this context, it is difficult to isolate the effect of only one parameter (Le., conductivity of the medium) from the other ones. This work is focused specifically on the analysis of the influence of temperature and pH on the impedance measurements. Different experiments were carried out using interdigitated microelectrodes (IDE) sensors for a geometry range in wine samples to adjust a proposed mathematical model of the impedance behavior. In the case of fermentation processes of alcoholic beverages, this methodology will help to isolate the chemical changes measured by impedance from temperature or pH variation. This model also provides the significance of the effect of each parameter on the impedance values. After the experimental validation, the model was used to correct the impedance values accordingly to the variation of each parameter showing its applicability to the real field. Finally, the proposed methodology can be easily applied and extended to other environments and sensors types. (C) 2018 Elsevier B.V. All rights reserved.
Autores: Anguiano, M.; Castilla, C.; Maška, M.; et al.
Revista: PLOS ONE
ISSN 1932-6203  Vol. 12  Nº 2  2017  págs. e0171417
Microfluidic devices are becoming mainstream tools to recapitulate in vitro the behavior of cells and tissues. In this study, we use microfluidic devices filled with hydrogels of mixed collagen-Matrigel composition to study the migration of lung cancer cells under different cancer invasion microenvironments. We present the design of the microfluidic device, characterize the hydrogels morphologically and mechanically and use quantitative image analysis to measure the migration of H1299 lung adenocarcinoma cancer cells in different experimental conditions. Our results show the plasticity of lung cancer cell migration, which turns from mesenchymal in collagen only matrices, to lobopodial in collagen-Matrigel matrices that approximate the interface between a disrupted basement membrane and the underlying connective tissue. Our quantification of migration speed confirms a biphasic role of Matrigel. At low concentration, Matrigel facilitates migration, most probably by providing a supportive and growth factor retaining environment. At high concentration, Matrigel slows down migration, possibly due excessive attachment. Finally, we show that antibody-based integrin blockade promotes a change in migration phenotype from mesenchymal or lobopodial to amoeboid and analyze the effect of this change in migration dynamics, in regards to the structure of the matrix. In summary, we describe and characterize a robust microfluidic platform and a set of software tools that can be used to study lung cancer cell migration under different microenvironments and experimental conditions. This platform could be used in future studies, thus benefitting from the advantages introduced by microfluidic devices: precise control of the environment, excellent optical properties, parallelization for high throughput studies and efficient use of therapeutic drugs.
Autores: Hisey, C. L.; Errazquin Irigoyen, M. ; et al.
ISSN 1387-2176  Vol. 19   Nº 2  2017  págs. 35
Cancer is a leading cause of mortality in the world, with osteosarcoma being one of the most common types among children between 1 and 14 years old. Current treatments including preoperative chemotherapy, surgery and postoperative chemotherapy produce several side effects with limited effectiveness. The use of lipid nanoparticles as biodegradable shells for controlled drug delivery shows promise as a more effective and targeted tumor treatment. However, in vitro validation of these vehicles is limited due to fluid stagnation in current techniques, in which nanoparticles sediment onto the bottom of the wells killing the cells by asphyxiation. In the current series of experiments, results obtained with methotrexate-lipid nanoparticles under dynamic assay conditions are presented as a promising alternative to current free drug based therapies. Effects on the viability of the U-2 OS osteosarcoma cell line of recirculation of cell media, free methotrexate and blank and methotrexate containing lipid nanoparticles in a 11 mu M concentration were successfully assessed. In addition, several designs for the microfluidic platform used were simulated using COMSOL-Multiphysics, optimized devices were fabricated using soft-lithography and simulated parameters were experimentally validated. Nanoparticles did not sediment to the bottom of the platform, demonstrating the effectiveness of the proposed system. Moreover, encapsulated methotrexate was the most effective treatment, as after 72 h the cell population was reduced nearly 40% while under free methotrexate circulation the cell population doubled. Overall, these results indicate that methotrexate-lipid nanoparticles are a promising targeted therapy for osteosarcoma treatment.
Autores: Becerro, S.; Paredes, J; Mujika, Maite; et al.
ISSN 1530-437X  Vol. 16  Nº 7  2016  págs. 1856 - 1864
Bacterial biofilms led to numerous problems in a wide variety of sectors as the medical environment, the food and water industry, or the naval sector. Completely developed biofilms are nearly impossible to eliminate due to the high antibiotic resistance these complex systems present. The lack of evidential indicators of their presence at the first stages of development makes antimicrobial treatments late and inadequate. Therefore, it is necessary to find new methods for the early detection of biofilm development in order to improve the efficiency of treatments by exposing bacterial cells before encapsulation in the extracellular matrix. For this purpose, this paper presents a real-time analysis of bacterial adhesion and biofilm growth by means of electrochemical measurements. Cyclic voltammetry and differential pulse voltammetry were performed with thin-film interdigitated microelectrode-based sensors. More sensitive and selective measurements were obtained with the second technique. Bacterial adhesion was detected 1 h after the initial inoculum, and three different redox centers were identified on bacterial surfaces. Finally, bacterial biofilm growth phases (lag, exponential, and stationary) were identified through the electrochemical measurements.
Autores: Tubia, Imanol, (Autor de correspondencia); Mujika, Maite; Artieda, Julio; et al.
Vol. 251  2016  págs. 241 - 247
Autores: Gómez, Mikel; Arana, Sergio; Mujika, Maite; et al.
ISSN 1530-437X  Vol. 15  Nº 2  2015  págs. 1216 - 1223
Autores: Zuzuarregui, A.; Souto, D.; Pérez-Lorenzo, E.; et al.
Revista: ANALYST
ISSN 0003-2654  Vol. 140  Nº 2  2015  págs. 654 - 660
This paper describes the design, implementation and validation of a sensitive and integral technology solution for endotoxin detection. The unified and portable platform is based on the electrochemical detection of endotoxins using a synthetic peptide immobilized on a thin-film biosensor. The work covers the fabrication of an optimized sensor, the biofunctionalization protocol and the design and implementation of the measuring and signalling elements (a microfluidic chamber and a portable potentiostat-galvanostat), framed ad hoc for this specific application. The use of thin-film technologies to fabricate the biosensing device and the application of simple immobilization and detection methods enable a rapid, easy and sensitive technique for in situ and real time LPS detection.
Autores: Pérez, Eva ; Zuzuarregui, A.; Arana, Sergio; et al.
ISSN 0273-2289  Vol. 174  Nº 7  2014  págs. 2492 - 2503
In this paper, a biological protocol for endotoxin detection has been developed and optimized by quartz crystal microbalance (QCM). The parameters involved in the formation of the self-assembled monolayer (SAM) have been analyzed, and a study of the pH of the ligand buffer has been performed in order to find the best condition for the ligand immobilization and, in consequence, for the endotoxin detection. The detection limit obtained with the characterized biological protocol corresponds to 1.90 mu g/ml. The effectiveness of the optimized biological protocol has been analyzed by cyclic voltammetry analysis.
Autores: Gallego-Perez, D.; Hansford, D.; et al.
ISSN 0956-5663  Vol. 61  2014  págs. 298 - 305
Lab on a chip (LOC) systems provide interesting and low-cost solutions for key studies and applications in the biomedical field. Along with microfluidics, these microdevices make single-cell manipulation possible with high spatial and temporal resolution. In this work we have designed, fabricated and characterized a versatile and inexpensive microfluidic platform for on-chip selective single-cell trapping and treatment using laminar co-flow. The combination of co-existing laminar flow manipulation and hydrodynamic single-cell trapping for selective treatment offers a cost-effective solution for studying the effect of novel drugs on single-cells. The operation of the whole system is experimentally simple, highly adaptable and requires no specific equipment. As a proof of concept, a cytotoxicity study of ethanol in isolated hepatocytes is presented. The developed microfluidic platform controlled by means of co-flow is an attractive and multipurpose solution for the study of new substances of high interest in cell biology research. In addition, this platform will pave the way for the study of cell behavior under dynamic and controllable fluidic conditions providing information at the individual cell level. Thus, this analysis device could also hold a great potential to easily use the trapped cells as sensing elements expanding its functionalities as a cell-based biosensor with single-cell resolution. (C) 2014 Elsevier B.V. All rights reserved.
Autores: Paredes, J; Becerro, S.; Arana, Sergio;
ISSN 0925-4005  Vol. 195  2014  págs. 667 - 676
Bacterial biofilms are presented in many different environments causing a wide variety of infectious processes. Biofilms at their mature stage are difficult to eradicate because of their inherent resistance to antimicrobial agents. Easy-to-integrate and in situ detection tools would provide early detection of bacterial presence allowing efficient prophylactic actions. Impedance microbiology has been postulated as a suitable technique that allows monitoring of bacterial biofilm growths in real time. In this work four different culturing setups were developed as testing platforms for measuring real time microbiological cultures that could mimic real field environments. Results suggest that the position of the sensors in regard to the dynamic conditions of the culture might affect the sensitivity and the target parameter. Capacitance and resistance are associated to different biological effects, surface coating and conductivity changes respectively. Relative variations of electrical parameters were recorded in the lab obtaining significant changes in few hours post-infection. It has been proven that biological coating cause largest variations in capacitance, up to 60%, while metabolic activity affects more the resistance giving a variation up to 15%. Fitting analysis has confirmed experimental results showing also the effect of the dead/alive ratio. (C) 2014 Elsevier B.V. All rights reserved.
Autores: Mujika, Maite; Zuzuarregui, A; et al.
ISSN 0168-1656  Vol. 186  2014  págs. 162 - 168
The current validated endotoxin detection methods, in spite of being highly sensitive, present several drawbacks in terms of reproducibility, handling and cost. Therefore novel approaches are being carried out in the scientific community to overcome these difficulties. Remarkable efforts are focused on the development of endotoxin-specific biosensors. The key feature of these solutions relies on the proper definition of the capture protocol, especially of the bio-receptor or ligand. The aim of the presented work is the screening and selection of a synthetic peptide specifically designed for LPS detection, as well as the optimization of a procedure for its immobilization onto gold substrates for further application to biosensors.
Autores: Paredes, J; Becerro, S.; Arana, Sergio;
ISSN 0167-7012  Vol. 100  2014  págs. 77 - 83
Impedance microbiology (IM) is a known technique that has been applied during the last decades to detect the presence of microorganisms in real samples in different fields: food industry, healthcare, environment, etc. Bacterial biofilms however have not been so far studied despite the fact that they are the most common microbiological formation and that they present resistance to antimicrobial agents. In situ early detection of bacterial biofilm is still a challenge nowadays that causes huge impact in many different scenarios. The ability to detect biofilm generation early will allow better and more efficient treatments preventing high costs and important problems. In this work a new performance of this technique with interdigitated microelectrode sensors (IDE) is proposed. A specific culturing setup where the sensors have been integrated in Petri Dishes has been developed. From the results it can be highlighted that low frequencies are more sensitive for detection than higher ones. The results achieved record variations of approximately 40% in the equivalent serial resistance after 10 h of culture. Electrical models have been successfully simulated to find the electrical behavior of the development of biofilms. Variations in both the capacitance and resistance were recorded during the growth of the microbes. (C) 2014 Elsevier B.V. All rights reserved.
Autores: Zuzuarregui, A.; Morant-Minana, C.; Pérez, Eva ; et al.
ISSN 1530-437X  Vol. 14  Nº 1  2014  págs. 270 - 277
In this paper, the implementation and characterization of a hand-held and simple biosensor for in-situ endotoxin determination are described. The integrated biosensor developed here is based on the electrochemical detection of endotoxin using polymyxin B as bioreceptor immobilized onto gold electrodes via a self-assembled monolayer. The cyclic voltammetry, electrochemical impedance spectroscopy, and atomic force microscopy were used to characterize the biosensor performance and properties throughout the functionalization process. In addition, a comparative analysis of the behavior and features of two alternative electrochemical techniques for endotoxin detection was carried out. The biosensing device fabricated by thin-film technologies provided a simple and robust method to detect low concentrations of endotoxin.
Autores: Paredes, J; Alonso-Arce, Maykel; Schmidt, C.; et al.
ISSN 1387-2176  Vol. 16  Nº 3  2014  págs. 365 - 374
Central venous catheters (CVC) are commonly used in clinical practice to improve a patient's quality of life. Unfortunately, there is an intrinsic risk of acquiring an infection related to microbial biofilm formation inside the catheter lumen. It has been estimated that 80 % of all human bacterial infections are biofilm-associated. Additionally, 50 % of all nosocomial infections are associated with indwelling devices. Bloodstream infections account for 30-40 % of all cases of severe sepsis and septic shock, and are major causes of morbidity and mortality. Diagnosis of bloodstream infections must be performed promptly so that adequate antimicrobial therapy can be started and patient outcome improved. An ideal diagnostic technology would identify the infecting organism(s) in a timely manner, so that appropriate pathogen-driven therapy could begin promptly. Unfortunately, despite the essential information it provides, blood culture, the gold standard, largely fails in this purpose because time is lost waiting for bacterial or fungal growth. This work presents a new design of a venous access port that allows the monitoring of the inner reservoir surface by means of an impedimetric biosensor. An ad-hoc electronic system was designed to manage the sensor and to allow communication with the external receiver. Historic data recorded and stored in the device was used as the reference value for the detection of bacterial biofilm. The RF communication system sends an alarm signal to the external receiver when a microbial colonization of the port occurs. The successful in vitro analysis of the biosensor, the electronics and the antenna of the new indwelling device prototype are shown. The experimental conditions were selected in each case as the closest to the clinical working conditions for the smart central venous catheter (SCVC) testing. The results of this work allow a new generation of this kind of device that could potentially provide more efficient treatments for catheter-related infections.
Autores: Paredes, J; Becerro, S.; Arizti, Fernando José; et al.
ISSN 0925-4005  Vol. 178  2013  págs. 663 - 670
Bacterial biofilms are a common cause of persistent and chronic infections, mostly related to implantable devices. In this context, Staphylococcus species are the most relevant microorganisms involved in causing high costs for the healthcare system. New diagnostic and/or therapeutic tools should be developed by providing in vivo analysis of the specific physiological parameters directly related to the status of the indwelling device. Monitoring the biofilm's biological evolution will allow an earlier diagnostic. Impedance microbiology is suggested as a proper technique for directly measuring the development of bacterial biofilms generated inside intravascular catheters. In this study we propose interdigitated microelectrode biosensors be integrated within those implantable devices. In vitro assays have been carried out in order to characterize this methodology as a detection and monitoring tool for bacterial biofilm development. Impedance spectroscopy (IS) was implemented in 96-well microtiter plates, leading to positive results in detecting and monitoring bacterial biofilm development. Two Staphylococcus aureus and two Staphylococcus epidermidis strains were successfully monitored during a 20-h culture, and results show that the low range of the frequency is the most suitable setting for measuring the maximum relative changes. (c) 2013 Elsevier B.V. All rights reserved.
Autores: Zuzuarregui, A.; Arana, Sergio; Pérez-Lorenzo, E.; et al.
ISSN 2194-8771  Vol. 2  Nº 2  2013  págs. 157 - 164
In this paper an electrochemical endotoxin biosensor consisting of an immobilized lipopolysaccharide (LPS) ligand, polymyxin B (PmB), is presented. Several parameters involved both in the device fabrication and in the detection process were analyzed to optimize the ligand immobilization and the interaction between PmB and LPS, aiming at increasing the sensitivity of the sensor. Di?erent electrochemical pre-treatment procedures as well as the functionalization methods were studied and evaluated. The use of a SAM (self-assembled monolayer) to immobilize PmB and the quanti?cation of the interactions via cyclic voltammetry allowed the development of a robust and simple device for in situ detection of LPS. Thus, the biosensor proposed in this work intends an approach to the demanding needs of the market for an integrated, portable and simple instrument for endotoxin detection.
Autores: Paredes, J; Becerro, S.; Arizti, Fernando José; et al.
ISSN 0956-5663  Vol. 38  Nº 1  2012  págs. 226 - 232
Detection of device-associated infectious processes is still an important clinical challenge. Bacteria grow adhered to the device surfaces creating biofilms that are resistant to antimicrobial agents, increasing mortality and morbidity. Thus there is need of a surgical procedure to remove the indwelling infected device. The elevated cost of these procedures, besides patients discomfort and increased risks, highlights the need to develop more efficient, accurate and rapid detection methods. Biosensors integrated with implantable devices will provide an effective diagnostic tool. In vivo, rapid and sensitive detection of bacteria attached to the device surfaces will allow efficient treatments. Impedance spectroscopy technique would be an adequate tool to detect the adherence and the growth of the microorganism by monitoring the impedance characteristics. In this work a label-free interdigitated microelectrode (IDAM) biosensor has been developed to be integrated with implantable devices. Impedance characterization of Staphylococcus epidermidis biofilms has been performed achieving electrical monitoring of the bacterial growths in a few hours from the onset of the infection. This pathogen represents the most common microorganism related to intravascular catheters associated infections. The experimental setup presented in this work, a modified CDC biofilm reactor, simulates the natural environment conditions for bacterial biofilm development. The results prove that the low range of frequency is the most suitable setting for monitoring biofilm development. Our findings prove the effectiveness of this technique which shows variations of 59% in the equivalent serial capacitance component of the impedance. (C) 2012 Elsevier B.V. All rights reserved.
Autores: Garcia, T.; Revenga, M.; Añorga, L.; et al.
ISSN 0925-4005  Vol. 161  Nº 1  2012  págs. 1030 - 1037
The development of a disposable electrochemical biosensor for selective Salmonella detection in presence of other pathogens is described. The device is based on thin-film gold electrodes and is fabricated employing standard microsystems technology. The method involves the immobilization of a thiolated capture probe able to hybridize with its complementary sequence (target). The hybridization event is detected using the ruthenium complex [Ru(NH3)(5)L](2+), where L is [3-(2-phenanthren-9-yl-vinyl)-pyridine]as electrochemical indicator. The combination of MEMS technology to fabricate electrodes with a predetermined configuration and the use of a hybridization redox indicator which interacts preferentially with dsDNA gear to the development of an approach that not only quantifies complementary target sequence, but also is selective to Salmonella in presence of other pathogens, which can act as potential interferents. In base of these results, a multianalyte detection platform including Salmonella, Lysteria and Escherichia coli has been developed. (C) 2011 Elsevier B.V. All rights reserved.
Autores: Garcia, T.; Revenga-Parraa, M.; Anorga, L.; et al.
ISSN 0925-4005  Vol. 161  Nº 1  2012  págs. 1030-1037
The development of a disposable electrochemical biosensor for selective Salmonella detection in presence of other pathogens is described. The device is based on thin-film gold electrodes and is fabricated employing standard microsystems technology. The method involves the immobilization of a thiolated capture probe able to hybridize with its complementary sequence (target). The hybridization event is detected using the ruthenium complex [Ru(NH3)(5)L](2+), where L is [3-(2-phenanthren-9-yl-vinyl)-pyridine]as electrochemical indicator. The combination of MEMS technology to fabricate electrodes with a predetermined configuration and the use of a hybridization redox indicator which interacts preferentially with dsDNA gear to the development of an approach that not only quantifies complementary target sequence, but also is selective to Salmonella in presence of other pathogens, which can act as potential interferents. In base of these results, a multianalyte detection platform including Salmonella, Lysteria and Escherichia coli has been developed. (C) 2011 Elsevier B.V. All rights reserved.
Autores: Manteca, A.; Mujika, Maite; Arana, Sergio;
ISSN 0956-5663  Vol. 26  Nº 8  2011  págs. 3705 - 3709
An immunomagnetic method for the selective and quantitative detection of biological species by means of a magnetoresistive biosensor and superparamagnetic particles has been optimized. In order to achieve this, a giant magnetoresistive [Co (5.10 nm)/Cu (2.47 nm)](20) multilayer structure has been chosen as the sensitive material, showing a magnetoresistance of 3.60% at 215 Oe and a sensitivity up to 0.19 Omega/Oe between 145 Oe and 350 Oe. The outward gold surface of the sensor is biofunctionalized with a Self-Assembled Monolayer (SAM). In addition, three different types of magnetic labels have been tested. 2 mu m diameter magnetic carriers (7.68 pg ferrite/particle) have shown the best response and they have induced a shift in the magnetoresistive hysteresis loops up to 9% at 175 Oe. (C) 2011 Elsevier B.V. All rights reserved.
Autores:  Zuzuarregui, A.; Perez-Lorenzo, E.; et al.
ISSN 0925-4005  Vol. 155  Nº 2  2011  págs. 667 - 672
One of the most remarkable procedures to immobilize some biological molecules onto surfaces is the use of self-assembled monolayers (SAMs). The aim of this work is to analyse the influence of formation conditions in the detection capability of two different SAMs. With this purpose two techniques have been implemented: the Quartz Crystal Microbalance with Dissipation (QCM-D) and the Surface Plasmon Resonance (SPR). Thus, several parameters usually involved in the SAM protocols have been characterized, i.e. the nature of the thiolated acid. The influence of its concentration and incubation time has been also taken into account. For the validation of these biological layers, the polymyxin B sulfate salt (Pm B), as ligand, and the lipopolysaccharide (LPS), as analyte, have been used. It is demonstrated that both in the QCM and the SPR, the use of SAM improves significantly the detection and immobilization of the target compound and an optimum SAM formation protocol is provided. (C) 2011 Elsevier B.V. All rights reserved.
Autores: Paredes, J; Tubia, Imanol; Arana, Sergio;
Libro:  Handbook of online and near-real-time methods in microorganism detection
2017  págs. 1 - 1
Autores: Becerro, S.; Paredes, J; Arana, Sergio;
Libro:  XIII Mediterranean Conference on Medical and Biological Engineering and Computing 2013
2014  págs. 880 - 883
Adhesion and growth of bacterial biofilms causes numerous problems in a wide variety of sectors, and more particularly, in those related to the medical environment or the industry. Treatment and disposal of this kind of infections is often hampered by the antibiotic resistance of biofilms as well as by a total lack of symptoms in the early stages. Therefore, it is necessary to find new methods for the early detection of biofilm development so as to improve the efficiency of treatments and to reduce the health complications suffered by patients. For this purpose, this paper focuses on the design and development of interdigitated microelectrode based biosensors that allow the detection of bacterial adhesion since the first steps of biofilm generation through impedance spectroscopy and electrochemistry. Both techniques have been proved as suitable tools for biofilm sensing and the results of the monitorization of bacterial biofilms of S. epidermidis in culture medium are presented. While variations of 40 % within a few hours of incubation have been achieved with impedimetric monitoring, electrochemistry increases both selectivity and sensitivity of the recorded measurements (variations of 60% have been obtained). Moreover, a multiparametric design for electrochemical and temperature measurements that will allow to obtain additional information of bacterial activity is presented.