Miquel Avella-Oliver

Aluminum Nanohole Arrays Fabricated on Polycarbonate for Compact Disc-Based Label-Free Optical Biosensing

Al nanohole array plasmonic biosensors have been fabricated on polycarbonate (PC) substrates from conventional compact discs (CD). Standard micro and nanofabrication processes have been used and optimized to be PC compatible. The viability of this CD-based plasmonic platform for label-free optical biosensing has been demonstrated through a competitive bioassay for biotin analysis using biotin-functionalized dextran-lipase conjugates immobilized on the transducer surface.

Total Analysis Systems with Thermochromic Etching Discs Technology

A new analytical system based on Thermochromic Etching Discs (TED) technology is presented. TED comprises a number of attractive features such as track independency, selective irradiation, a high power laser, and the capability to create useful assay platforms. The analytical versatility of this tool opens up a wide range of possibilities to design new compact disc-based total analysis systems applicable in chemistry and life sciences. In this paper, TED analytical implementation is described and discussed, and their analytical potential is supported by several applications. Microarray immunoassay, immunofiltration assay, solution measurement, and cell culture approaches are herein addressed in order to demonstrate the practical capacity of this system. The analytical usefulness of TED technology is herein demonstrated, describing how to exploit this tool for developing truly integrated analytical systems that provide solutions within the point of care framework.

Aluminum Nanoholes for Optical Biosensing

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.

INSEL: an in silico method for optimizing and exploring biorecognition assays

A practical in silico method for optimizing and exploring biointeraction-based events is developed.

Diffractive Protein Gratings as Optically Active Transducers for High-Throughput Label-free Immunosensing

A novel label-free biosensing approach based on bioreceptor networks patterned as diffractive gratings (biogratings) has been developed. Nanogrooved structures were used as optically active scaffolds for producing arrays of functional BSA biogratings on low energy surfaces by a water-assisted variant of microcontact printing. An analytical scanner, comprising a LightScribe compact disk drive, was developed to measure the diffraction patterns of these biogratings, thus allowing biointeractions to be quantitatively sensed in a multiplex and label-free fashion by means of diffraction efficiency changes. The approach was demonstrated by immunoassaying IgGs, reaching well-correlated responses with quantification and detection limits of 1.3 and 5.2 nM, respectively. These results provide appealing insights into cost-effective, portable, and scalable alternatives for designing new analytical technologies based on diffractive gratings of bioreceptors.

More about sampling and estimation of mercaptans in air samples

Several strategies have been developed for sampling and determination of volatile thiols. The selectivity and sensitivity of the proposed methodologies are achieved by using a specific derivatizing reagent. The different procedures assayed are based on air sampling followed by derivatization of the analytes with OPA and isoleucine in alkaline solution. The derivatization products are separated and determined by liquid chromatography and fluorescence detection. To start, the derivatization conditions and stability of the derivates have been studied in order to establish the storage conditions. In general, the strategies studied consisted on trapping and detivatization the thiol compound on different support; a solution (Impinger) or sorbent (C₁₈ cartridges or glass fiber filter). The analytical properties of the different strategies have been obtained and compared. Procedures are recommended upon specific situations.

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

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.

Indirect Microcontact Printing to Create Functional Patterns of Physisorbed Antibodies

Microcontact printing (µCP) 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 µCP 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 µCP. This study presents the approach, assesses bovine serum albumin as backfilling agent for indirect µCP on different materials, reports the limitations of standard µCP on the functionality of patterned antibodies, and demonstrates the capabilities of indirect µCP 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 µCP in an immunoassay to detect human immunoglobulin E.

Detection of pathogenic bacteria using immunofiltration and lightscribe technology

The detection of pathogenic bacteria is key for the identification and prevention and of problems related to health and safety. Accurate and quick detection and quantification of pathogen microorganisms in food, drinking water and in clinical diagnostics using cost-effective methodologies are greatest challenges currently facing food industry, health and environmental fields. A rapid and sensitive biosensor, based on immunological methods, was developed for bacteria detection using LightScribe disc as platform. We are able to detect between 0 and 106 CFU/mL in only 1.5 hours without the need for sample pre-concentration. The cross-reactivity study and individual ready-to-eat meat samples were inoculated with live bacteria to demonstrate proof-of-concept for real samples.