A label-free diffraction-based sensing displacement immunosensor toquantify low molecular weight organic compounds

[EN] Herein we present a diffractometric immunosensor to quantify low molecular weight organic compounds in a label-free, simple, and sensitive fashion. The approach is based on patterning analyte analogues (haptens) on solid surfaces according to a diffractive structure, and then loading specific antibodies on them to be subsequently displaced by free analytes in solution. This displacement generates a measurable change in the diffractive response that enables to quantify the analyte concentration. In this study we address the fabrication, optimization, and assessment of these diffractive structures of biological probes and their application to the analysis of atrazine, an organic compound extensively used as pesticide. This immunosensor displays well-correlated dose-response curves that reach a detection limit of 1.1¿ng¿mL¿1 of atrazine in label-free conditions. From a general viewpoint, this study also aims to provide insights into exploiting this approach towards prospective in-field analysis and screening strategies to sense multiple low molecular weight compounds in label-free conditions.This work was supported by the Spanish Ministry of Economy and Competitiveness (CTQ2013-45875-R and FIS2011-23175), FEDER, and the Generalitat Valenciana (PROMETEO II/2014/040 and PROMETEO II/2014/072). Special thanks go to Richard A. McAloney and M. Cynthia Goh for hosting M.A.-O. as visiting researcher, sharing their expertise, and offering their valuable support. M.A.-O. also acknowledges the FPI program of the Spanish Ministry of Economy and Competitiveness for a PhD and an EEBB mobility grant.Avella-Oliver, M.; Ferrando Martín, V.; Monsoriu Serra, JA.; Puchades, R.; Maquieira Catala, A. (2018). A label-free diffraction-based sensing displacement immunosensor toquantify low molecular weight organic compounds. Analytica Chimica Acta. 1033:173-179. https://doi.org/10.1016/j.aca.2018.05.060S173179103

Sistemas Analíticos Totales en Superficies termocrómicas

Ministerio de Economía y Competitividad (CTQ2013-45875-R y Programa FPI) y Generalitat Valenciana (PROMETEO II 2014/040).Avella-Oliver, M.; Morais, S.; Puchades, R.; Maquieira Catala, Á. (2015). Sistemas Analíticos Totales en Superficies termocrómicas. Boletín de la Sociedad Española de Química Analítica. 50(6):29-30. http://hdl.handle.net/10251/103297S293050

Enhancing the sensitivity in optical biosensing by striped arrays and frequency-domain analysis

[EN] An approach to enhance the sensitivity of optical biosensors is developed. It is based on patterning strips of biochemical probes and signal processing (frequency-domain analysis, FDA) to the resulting analytical data after a biorecognition assay. This paper introduces FDA, demonstrates for the first time its potential in real bioanalytical systems, describes its critical parameters, and discusses how to optimize them to efficiently exploit this approach for optical biosensing. The results show that FDA enables for the selective identification and removal of the undesired noise contributions from the analytical signal arising from a biorecognition event of interest, thus increasing signal-to-noise ratios and, therefore, enhancing the sensitivity of the analysis. In this study, we proof the concept with a model immunassay system for IgGs detection (BSA/anti-BSA) that achieves a sensitivity enhancement of up to 3 orders of magnitude, and then FDA is also demonstrated in a sandwich immunoassay to quantify casein that reaches a limit of detection of 4 ng/mL (174 pM). Beyond these particular assays, this work also addres to stablish the basis of this approach and to provide keys to stimulate future developments that expand the potential of FDA to other biorecognition assays, transduction systems, and applications.This research was supported by FEDER and the Spanish Ministry of Economy and Competitiveness (CTQ2016-75749-R).Sancho-Fornes, G.; Avella-Oliver, M.; Carrascosa Rubio, J.; Morais, S.; Puchades, R.; Maquieira Catala, A. (2019). Enhancing the sensitivity in optical biosensing by striped arrays and frequency-domain analysis. Sensors and Actuators B Chemical. (281):432-438. https://doi.org/10.1016/j.snb.2018.10.130S43243828

Indirect Microcontact Printing to Create Functional Patterns of Physisorbed Antibodies

[EN] Microcontact printing (mu CP) is a practical and versatile approach to create nanostructured patterns of biomolecular probes, but it involves conformational changes on the patterned bioreceptors that often lead to a loss on the biological activity of the resulting structures. Herein we introduce indirect mu CP to create functional patterns of bioreceptors on solid substrates. This is a simple strategy that relies on physisorbing biomolecular probes of interest in the nanostructured gaps that result after patterning backfilling agents by standard mu CP. This study presents the approach, assesses bovine serum albumin as backfilling agent for indirect mu CP on different materials, reports the limitations of standard mu CP on the functionality of patterned antibodies, and demonstrates the capabilities of indirect mu CP to solve this issue. Bioreceptors were herein structured as diffractive gratings and used to measure biorecognition events in label-free conditions. Besides, as a preliminary approach towards sensing biomarkers, this work also reports the implementation of indirect mu CP in an immunoassay to detect human immunoglobulin E.This research was funded by the Spanish Ministry of Economy and Competitiveness (CTQ2016-75749-R), FEDER, Generalitat Valenciana (PROMETEO II/2014/040), and Universitat Politecnica de Valencia (FPI program).Juste-Dolz, AM.; Avella-Oliver, M.; Puchades, R.; Maquieira Catala, A. (2018). Indirect Microcontact Printing to Create Functional Patterns of Physisorbed Antibodies. Sensors. 18(9). https://doi.org/10.3390/s18093163S316318

Disk-based one-dimensional photonic crystal slabs for label-free immunosensing

[EN] One-dimensional photonic crystal slabs are periodic optical nanostructures that produce guided-mode resonance. They couple part of the incident light into the waveguide generating bandgaps in the transmittance spectrum, whose position is sensitive to refractive index variations on their surface. In this study, we present one-dimensional photonic crystal slab biosensors based on the internal nanogrooved structure of Blu-ray disks for label-free immunosensing. We demonstrated that this polycarbonate structure coated with a critical thickness of TiO2 generates guided-mode resonance. Its optical behavior was established comparing it with other compact disk structures. The results were theoretically calculated and experimentally demonstrated, all them being in agreement. The bioanalytical performance of these photonic crystals was experimentally demonstrated in a model assay to quantify IgGs as well as in two immunoassays to determine the biomarkers C-reactive protein and lactate dehydrogenase (detection limits of 0.1, 87, and 13 nM, respectively). The results are promising towards the development of new low-cost, portable, and label-free optical biosensors that join these photonic crystals with dedicated bioanalytical scanners based on compact disk drives.This research was supported by FEDER grants and the Spanish Ministry of Economy and Competitiveness projects (CTQ2013-45875-R and CTQ2016-75749-R).Sancho-Fornes, G.; Avella-Oliver, M.; Carrascosa Rubio, J.; Fernández-Sánchez, ME.; Brun, EM.; Maquieira Catala, Á. (2019). Disk-based one-dimensional photonic crystal slabs for label-free immunosensing. Biosensors and Bioelectronics. 126:315-323. https://doi.org/10.1016/j.bios.2018.11.005S31532312

Biogratings: nanoestructuras de biomoléculas para análisis químico mediante difracción de luz

[ES] La química analítica es una ciencia dinámica que integra multitud de disciplinas. Desde hace algún tiempo, parte del progreso de la química analítica es fruto de la convergencia entre diferentes campos. Entre otros, el uso de biomacromoléculas con fines analíticos proporciona una selectividad excelente, y la implementación de nanomateriales permite utilizar fenómenos fotónicos de transducción que favorecen el desarrollo de biosensores. 1,2 En los últimos años parte de las actividades de nuestro grupo de investigación se enmarcan en este contexto.3¿6 En particular, esta comunicación se centra en una estrategia especialmente interesante que hemos denominado con el término biogratings. Llamamos biograting a una capa de biomacromoléculas (proteínas, ácidos nucleicos, etc.) inmovilizadas sobre una superficie sólida y estructurada según un patrón periódico diseñado para difractar la luz incidente. En otras palabras, son nanoestructuras difractivas de biomoléculas sobre sustratos sólidos. La Figura 1 muestra una configuración típica de biograting constituido por un patrón de líneas de proteínas inmovilizadas (strips) y líneas vacías (gaps) dispuestas de forma periódica. El interés analítico de estas nanoestructuras reside en que son capaces de aprovechar la difracción de la luz para transformar interacciones biorreceptoranalito en señales ópticas fácilmente medibles. Entre otras capacidades que se discutirán a continuación, cabe destacar el poder realizar ensayos de biorreconocimiento sin marcaje y a tiempo real, para el análisis directo de muestras complejas. Esta comunicación expone las características de los biogratings y los aspectos clave en su desarrollo: fabricación, estrategias de transducción posibles, y su aplicación en biosensado.Esta publicación es parte del proyecto de I+D+i PID2019-110713RB-I00 financiado por MCIN/AEI/10.13039/501100011033 y FEDER Una manera de hacer Europa , y del proyecto PROMETEO/2020/094 financiado por la Generalitat Valenciana. Financiado con Ayuda a Primeros Proyectos de Investigación (PAID-06-22), Vicerrectorado de Investigación de la Universitat Politècnica de València (UPV).Avella-Oliver, M.; Juste-Dolz, AM.; Fernández-Sánchez, ME.; Maquieira Catala, A. (2023). Biogratings: nanoestructuras de biomoléculas para análisis químico mediante difracción de luz. Actualidad Analítica (Online). (81):30-35. http://hdl.handle.net/10251/20521930358

Aluminum Nanoholes for Optical Biosensing

[EN] Sub-wavelength diameter holes in thin metal layers can exhibit remarkable optical features that make them highly suitable for (bio)sensing applications. Either as efficient light scattering centers for surface plasmon excitation or metal-clad optical waveguides, they are able to form strongly localized optical fields that can effectively interact with biomolecules and/or nanoparticles on the nanoscale. As the metal of choice, aluminum exhibits good optical and electrical properties, is easy to manufacture and process and, unlike gold and silver, its low cost makes it very promising for commercial applications. However, aluminum has been scarcely used for biosensing purposes due to corrosion and pitting issues. In this short review, we show our recent achievements on aluminum nanohole platforms for (bio)sensing. These include a method to circumvent aluminum degradation-which has been successfully applied to the demonstration of aluminum nanohole array (NHA) immunosensors based on both, glass and polycarbonate compact discs supports-the use of aluminum nanoholes operating as optical waveguides for synthesizing submicron-sized molecularly imprinted polymers by local photopolymerization, and a technique for fabricating transferable aluminum NHAs onto flexible pressure-sensitive adhesive tapes, which could facilitate the development of a wearable technology based on aluminum NHAs.The authors gratefully acknowledge financial support from MINECO projects, Spain (TEC2012-31145, CTQ2012-37573-C02 and CTQ 2013-45875-R).Angulo Barrios, C.; Canalejas Tejero, V.; Herranz, S.; Urraca, J.; Moreno-Bondi, MC.; Avella-Oliver, M.; Maquieira Catala, Á.... (2015). Aluminum Nanoholes for Optical Biosensing. Biosensors. 5(3):417-431. https://doi.org/10.3390/bios50304174174315

Towards photochromic and thermochromic biosensing

Past , Present and Future challenges of Biosensors and Bioanalytical tools in Analytical Chemistry: a tribute to Prof Marco Mascini[EN] Photochromism and thermochromism are interesting physicochemical phenomena applied in the chemistry, health and biology fields and others. Nonetheless, exploiting these chromo-switchable properties in biosensing remains unexplored, and very few results have been reported in the scientific literature. Along these lines, the rich mature knowledge of these phenomena supports the challenge of facing the development of photo- and thermochromic bioanalytical systems. This work discusses potential approaches to exploit photochromism and thermochromism for biosensing, and it reviews the state-of-the-art of these phenomena in the surrounding areas of biosensing in order to plot a stimulating scenario for innovation.This work has been supported by the Spanish Ministry of Economy and Competitiveness (CTQ2013-45875-R), FEDER, and the Generalitat Valenciana (PROMETEO II/2014/040). M.A.-O. acknowledges the Spanish Ministry of Economy and Competitiveness for an FPI program grant.Avella-Oliver, M.; Morais, S.; Puchades, R.; Maquieira Catala, Á. (2016). Towards photochromic and thermochromic biosensing. Trends in Analytical Chemistry. 79:37-45. https://doi.org/10.1016/j.trac.2015.11.021S37457

Patterned Biolayers of Protein Antigens for Label-Free Biosensing in Cow Milk Allergy

[EN] This paper focuses on creating one-dimensional diffractive grooved structures of antigen proteins on glass substrates for the label-free detection of antibodies to dairy allergens. In particular, the fabrication of protein structures is carried out by combining microcontact printing with physisorption, imines coupling, and thiol-ene click chemistry. The work first sets up these patterning methods and discusses and compares the main aspects involved in them (structure, biolayer thickness, functionality, stability). Homogeneous periodic submicron structures of proteins are created and characterized by diffractive measurements, AFM, FESEM, and fluorescence scanning. Then, this patterning method is applied to proteins involved in cow milk allergy, and the resulting structures are implemented as optical transducers to sense specific immunoglobulins G. In particular, gratings of bovine serum albumin, casein, and ß-lactoglobulin are created and assessed, reaching limits of detection in the range of 30¿45 ng·mL¿1 of unlabeled antibodies by diffractive biosensing.Grant PID2019-110713RB-I00 funded by MCIN/AEI/10.13039/501100011033 and cofunded by "ERDF A way of making Europe", Generalitat Valenciana (PROMETEO/2020/094), and Universitat Politecnica de Valencia (PAID-06-22).Juste-Dolz, AM.; Fernández-Sánchez, ME.; Puchades, R.; Avella-Oliver, M.; Maquieira Catala, A. (2023). Patterned Biolayers of Protein Antigens for Label-Free Biosensing in Cow Milk Allergy. Biosensors. 13(2). https://doi.org/10.3390/bios1302021413

Label-free SERS analysis of proteins and exosomes with large-scale substrates from recordable compact disks

[EN] A central aspect to fully reach the biosensing scope of plasmonics beyond the research environment is its implementation in inexpensive and homogeneous functional nanostructured materials that can be manufactured in a large-scale fashion. Herein, we study the capabilities of consumer-grade compact disk technology for label-free SERS analysis of complex biological targets. Substrates from regular recordable disks (CD-R and DVD-R) coated with silver exhibit significant Raman enhancement. The magnitude of this enhancement depends on the nanostructure on the polycarbonate substrate, the silver thickness, and the excitation wavelength. The Raman fingerprint of hemoglobin and exosome samples were experimentally obtained in label-free conditions, which demonstrates the biosensing potential of this approach and suggests prospective developments towards fully exploiting the bioanalytical capabilities of SERS in point-of-care settings. (C) 2017 Elsevier B.V. All rights reserved.This work was supported by the Spanish Ministry of Economy and Competitiveness (CTQ2013-45875-R), FEDER, and the Generalitat Valenciana (PROMETEO II/2014/040). S.W-H would like to acknowledge financial support from UCDavis Office of Research. M.A-O also acknowledges the FPI program of the Spanish Ministry of Economy and Competitiveness for a PhD and an EEBB grant. We would like to thank Dr. Randy P. Carney for the exosome samples.Avella-Oliver, M.; Puchades, R.; Wachsmann-Hogiu, S.; Maquieira Catala, Á. (2017). Label-free SERS analysis of proteins and exosomes with large-scale substrates from recordable compact disks. Sensors and Actuators B Chemical. 252:657-662. https://doi.org/10.1016/j.snb.2017.06.058S65766225