2010 Annual International Conference of the Ieee Engineering in Medicine and Biology Society (Embc), 2010
Point-of-care diagnostic devices typically require six distinct qualities: they must deliver at l... more Point-of-care diagnostic devices typically require six distinct qualities: they must deliver at least the same sensitivity and selectivity, and for a cost per assay no greater than that of today's central lab technologies, deliver results in a short period of time (<15 min at GP; <2h in hospital), be portable or at least small in scale, and require no or extremely little sample preparation. State-of-the-art devices deliver information of several markers in the same measurement.
The negative epoxy-based SU-8 photoresist has a wide variety of applications within the semicondu... more The negative epoxy-based SU-8 photoresist has a wide variety of applications within the semiconductor industry, photonics and lab-on-a-chip devices, and it is emerging as an alternative to silicon-based devices for sensing purposes. In the present work, biotinylation of the SU-8 polymer surface promoted by light is reported. As a result, a novel, effective, and low-cost material, focusing on the immobilization of bioreceptors and consequent biosensing, is developed. This material allows the spatial discrimination depending on the irradiation of desired areas. The most salient feature is that the photobiotin may be directly incorporated into the SU-8 curing process, consequently reducing time and cost. The potential use of this substrate is demonstrated by the immunoanalytical detection of the synthetic steroid gestrinone, showing excellent performances. Moreover, the naked eye biodetection due to the transparent SU-8 substrate, and simple instrumental quantification are additional advantages.
7th IEEE International Conference on Group IV Photonics, 2010
We report an experimental demonstration of single-strand DNA detection at room temperature using ... more We report an experimental demonstration of single-strand DNA detection at room temperature using a photonic crystal waveguide based optical sensor. A detection limit of 19.8nM is obtained.
ABSTRACT We report an experimental demonstration of DNA detection using a photonic crystal wavegu... more ABSTRACT We report an experimental demonstration of DNA detection using a photonic crystal waveguide based optical sensor. A detection limit of 110nM is achieved for hybridized biotinylated DNA oligomers on the streptavidin-coated Silicon biosensor.
Abstract Narrow polarization-mixing resonances in planar photonic crystals are studied as candida... more Abstract Narrow polarization-mixing resonances in planar photonic crystals are studied as candidate components for label-free refractive index sensors for detecting bacteria causing sepsis through the identification of DNA strands
This work addresses the main topics related to the photopolymerization process to develop and to ... more This work addresses the main topics related to the photopolymerization process to develop and to monitor the analytical signal derived from biorecognition assays. We review basic aspects of photopolymerization, together with the nature and the reactivity of the chemicals involved. Focusing on DNA and protein determination and medical applications, we envisage as relevant photopolymers that generate biocompatible hydrogels.
A novel approach that may potentially be used to study biomolecular interactions including the si... more A novel approach that may potentially be used to study biomolecular interactions including the simultaneous determination of structural and kinetic binding parameters is described in this Article for the first time. It allows a rigid distinction between the possible reaction mechanisms of biomolecular recognition, induced fit and conformational selection. The relative importance of the two pathways is determined not by comparing rate constants but the structural aspects of the interaction instead. So the exact location of antigen molecules with respect to the capture antibody is depicted experimentally, avoiding the use of X-ray crystallography. The proposed pattern is applied to study the anti-BSA Immunoglobulin G (IgG)-free Bovine Serum Albumin (BSA) interaction, in which IgG is anchored on a silicon chip sensing surface in an oriented manner. The exact location of the receptor with respect to the ligand was monitored during the binding process, thus drawing the full reaction scheme. IgG forms an asymmetric (FabBSA) 2 complex with BSA molecules, even though it has two identical fragment antigen binding arms. This is thought to be due to steric hindrance caused by the binding of the first BSA molecule. Furthermore, the proposed model allows one to characterize reaction intermediates without the need of isolating them. These intermediates not characterized in situ so far are the keystone to understand how antibodies are able to identify antigens.
a b s t r a c t DNA binding chemistry on silicon surface has been investigated. Aminated oligonuc... more a b s t r a c t DNA binding chemistry on silicon surface has been investigated. Aminated oligonucleotide probes were immobilized on the chip surface by chemical silanization and further covalent attachment. The chemistries employed were the classical 3-aminopropyltriethoxysilane/glutaraldehyde and, for comparison purposes, the novel 3-isocyanatepropyltriethoxysilane, that allows the direct attachment of the aminated probe. Alternatively, a thiolated oligonucleotide was also photochemically immobilized by means of a thioether linkage. The experiments were followed label-free by Dual Polarization Interferometry. All chemical and photochemical methods gave rise to a probe density immobilization in the order of 1.0-2.5 × 10 10 molecules/mm 2 , similar to the values reported for other chemistries. The obtained data suggest that DNA strands are anchored in a different conformation depending on the immobilization method employed. In order to avoid non-specific binding of target molecules, ethanolamine and inert proteins were assayed, and successful results were obtained when using small size proteins such as gelatine. Hybridization efficiency was around 20% for aminosilane-based immobilized probes, and more than 4-fold this value when the other immobilization methods were employed. The ability for recognition complementary DNA strands discriminating non-complementary ones was applied for species identification in mixtures. (J.L. López-Paz), [email protected] (M.Á. González-Martínez), [email protected] (J. Escorihuela), [email protected] (M.-J. Bañuls), [email protected] (R. Puchades), [email protected] (Á. Maquieira). 0925-4005/$ -see front matter
We demonstrate label-free molecule detection by using an integrated biosensor based on a Si 3 N4/... more We demonstrate label-free molecule detection by using an integrated biosensor based on a Si 3 N4/Si0 2 slotwaveguide microring resonator. Bovine serum albumin (BSA) and anti-BSA molecular binding events on the sensor surface are monitored through the measurement of resonant wavelength shifts with varying biomolecule concentrations. The biosensor exhibited sensitivities of 1.8 and 3.2 nm/(ng/mm 2 ) for the detection of anti-BSA and BSA, respectively. The estimated detection limits are 28 and 16 pg/mm 2 for anti-BSA and BSA, respectively, limited by wavelength resolution.
We report an experimental demonstration of single-strand DNA (ssDNA) detection at room temperatur... more We report an experimental demonstration of single-strand DNA (ssDNA) detection at room temperature using a photonic-crystal-waveguide-based optical sensor. The sensor surface was previously biofunctionalized with ssDNA probes to be used as specific target receptors. Our experiments showed that it is possible to detect these hybridization events using planar photonic-crystal structures, reaching an estimated detection limit as low as 19:8 nM for the detection of the complementary DNA strand.
In this letter, we present experimental results of antibody detection using a biosensor based on ... more In this letter, we present experimental results of antibody detection using a biosensor based on photonic bandgap structures, which are interrogated using a power-based readout technique. This interrogation method allows a realtime monitoring of the association process between the antigen probes and the target antibodies, allowing the instantaneous observation of any interaction event between molecules. because etunable lasers and optical spectrum analyzers are avoided for the readout, a drastic reduction of the final cost of the platform is obtained. Furthermore, the performance of the biosensing system is significantly enhanced due to the large number of data values obtained per second.
We report experimental results of label-free anti-bovine serum albumin (anti-BSA) antibody detect... more We report experimental results of label-free anti-bovine serum albumin (anti-BSA) antibody detection using a SOI planar photonic crystal waveguide previously bio-functionalized with complementary BSA antigen probes. Sharp fringes appearing in the slow-light regime near the edge of the guided band are used to perform the sensing. We have modeled the presence of these band edge fringes and demonstrated the possibility of using them for sensing purposes by performing refractive index variations detection, achieving a sensitivity of 174.8 nm/RIU. Then, label-free anti-BSA biosensing experiments have been carried out, estimating a surface mass density detection limit below 2.1 pg/mm 2 and a total mass detection limit below 0.2 fg.
The potential of thiol-ene chemistry as a selective strategy to functionalize silicon materials f... more The potential of thiol-ene chemistry as a selective strategy to functionalize silicon materials for DNA microarraying is demonstrated and applied to discriminate genetic variations.
The selective introduction of functional groups on the surface of silicon nitride/silicon oxide n... more The selective introduction of functional groups on the surface of silicon nitride/silicon oxide nanostructures was studied. Chemical strategies based on organosilane, Si-H and N-H reactivities were assayed. Among these strategies, the use of glutaraldehyde to selectively immobilize biomolecules only on the silicon nitride part of the chip surface was the most effective for the covalent attachment of proteins, maintaining also their bioavailability. The biomolecule surface coverage results up to 80% and the modification is selective versus silicon oxide; the biomolecule attaching only to silicon nitride and leaving the silicon oxide area of the device unmodified. The effectiveness of our novel selective surface modification procedure is also supported by comparing experimental and numerical calculations of the optical performance of a label-free optical ring resonator based on Si 3 N 4 /SiO 2 slot-waveguides.
In a previous work we introduced the term Bio-Photonic Sensing Cells (BICELLs), referred to perio... more In a previous work we introduced the term Bio-Photonic Sensing Cells (BICELLs), referred to periodic networks of nano-pillar suitable for biosensing when are vertically interrogated. In this article, we demonstrate the biosensing capabilities of a type of micrometric size BICELLs made of SU-8 nano-pillars fabricated over transparent substrates. We verify the biochips functionality comparing the theoretical simulations with the experimental results when are optically interrogated in transmission. We also demonstrate a sensitivity enhancement by reducing the pitch among nano-pillars from 800 to 700 nm. Thus, the Limit of Detection achievable in these types of BICELLs is in the order of 64 pg/mL for 700 nm in pitch among nano-pillars in comparison with 292 pg/mL for 800 nm in pitch when are interrogated by Fourier Transform Visible and Infrared Spectrometry. The experiments exhibited a good reproducibility with a relative standard deviation of 0.29% measured within 8 days for a specific concentration.
We developed biophotonic sensing arrays of 60 × 60 m 2 made of periodic lattices of high aspect r... more We developed biophotonic sensing arrays of 60 × 60 m 2 made of periodic lattices of high aspect ratio SU-8 nano-pillars in order to demonstrate their capability for label-free molecule detection, as well as the sensitivity enhancement in comparison with a single layer of SU-8. The biophotonic sensing arrays, that we call BICELLs (Biophotonic sensing cells), are interrogated vertically by using micron spot size Fourier transform visible and IR spectrometry (FT-VIS-IR). We monitored the surface immobilization of bovine serum albumin (BSA) antigen and anti-BSA antibody (aBSA) recognition. The bioassay exhibits a limit of detection (LOD) in the order of 2 ng/ml limited by the wavenumber uncertainty during the interrogation process. We also estimated and compared the theoretical biolayer thickness with previous results.
2010 Annual International Conference of the Ieee Engineering in Medicine and Biology Society (Embc), 2010
Point-of-care diagnostic devices typically require six distinct qualities: they must deliver at l... more Point-of-care diagnostic devices typically require six distinct qualities: they must deliver at least the same sensitivity and selectivity, and for a cost per assay no greater than that of today's central lab technologies, deliver results in a short period of time (<15 min at GP; <2h in hospital), be portable or at least small in scale, and require no or extremely little sample preparation. State-of-the-art devices deliver information of several markers in the same measurement.
The negative epoxy-based SU-8 photoresist has a wide variety of applications within the semicondu... more The negative epoxy-based SU-8 photoresist has a wide variety of applications within the semiconductor industry, photonics and lab-on-a-chip devices, and it is emerging as an alternative to silicon-based devices for sensing purposes. In the present work, biotinylation of the SU-8 polymer surface promoted by light is reported. As a result, a novel, effective, and low-cost material, focusing on the immobilization of bioreceptors and consequent biosensing, is developed. This material allows the spatial discrimination depending on the irradiation of desired areas. The most salient feature is that the photobiotin may be directly incorporated into the SU-8 curing process, consequently reducing time and cost. The potential use of this substrate is demonstrated by the immunoanalytical detection of the synthetic steroid gestrinone, showing excellent performances. Moreover, the naked eye biodetection due to the transparent SU-8 substrate, and simple instrumental quantification are additional advantages.
7th IEEE International Conference on Group IV Photonics, 2010
We report an experimental demonstration of single-strand DNA detection at room temperature using ... more We report an experimental demonstration of single-strand DNA detection at room temperature using a photonic crystal waveguide based optical sensor. A detection limit of 19.8nM is obtained.
ABSTRACT We report an experimental demonstration of DNA detection using a photonic crystal wavegu... more ABSTRACT We report an experimental demonstration of DNA detection using a photonic crystal waveguide based optical sensor. A detection limit of 110nM is achieved for hybridized biotinylated DNA oligomers on the streptavidin-coated Silicon biosensor.
Abstract Narrow polarization-mixing resonances in planar photonic crystals are studied as candida... more Abstract Narrow polarization-mixing resonances in planar photonic crystals are studied as candidate components for label-free refractive index sensors for detecting bacteria causing sepsis through the identification of DNA strands
This work addresses the main topics related to the photopolymerization process to develop and to ... more This work addresses the main topics related to the photopolymerization process to develop and to monitor the analytical signal derived from biorecognition assays. We review basic aspects of photopolymerization, together with the nature and the reactivity of the chemicals involved. Focusing on DNA and protein determination and medical applications, we envisage as relevant photopolymers that generate biocompatible hydrogels.
A novel approach that may potentially be used to study biomolecular interactions including the si... more A novel approach that may potentially be used to study biomolecular interactions including the simultaneous determination of structural and kinetic binding parameters is described in this Article for the first time. It allows a rigid distinction between the possible reaction mechanisms of biomolecular recognition, induced fit and conformational selection. The relative importance of the two pathways is determined not by comparing rate constants but the structural aspects of the interaction instead. So the exact location of antigen molecules with respect to the capture antibody is depicted experimentally, avoiding the use of X-ray crystallography. The proposed pattern is applied to study the anti-BSA Immunoglobulin G (IgG)-free Bovine Serum Albumin (BSA) interaction, in which IgG is anchored on a silicon chip sensing surface in an oriented manner. The exact location of the receptor with respect to the ligand was monitored during the binding process, thus drawing the full reaction scheme. IgG forms an asymmetric (FabBSA) 2 complex with BSA molecules, even though it has two identical fragment antigen binding arms. This is thought to be due to steric hindrance caused by the binding of the first BSA molecule. Furthermore, the proposed model allows one to characterize reaction intermediates without the need of isolating them. These intermediates not characterized in situ so far are the keystone to understand how antibodies are able to identify antigens.
a b s t r a c t DNA binding chemistry on silicon surface has been investigated. Aminated oligonuc... more a b s t r a c t DNA binding chemistry on silicon surface has been investigated. Aminated oligonucleotide probes were immobilized on the chip surface by chemical silanization and further covalent attachment. The chemistries employed were the classical 3-aminopropyltriethoxysilane/glutaraldehyde and, for comparison purposes, the novel 3-isocyanatepropyltriethoxysilane, that allows the direct attachment of the aminated probe. Alternatively, a thiolated oligonucleotide was also photochemically immobilized by means of a thioether linkage. The experiments were followed label-free by Dual Polarization Interferometry. All chemical and photochemical methods gave rise to a probe density immobilization in the order of 1.0-2.5 × 10 10 molecules/mm 2 , similar to the values reported for other chemistries. The obtained data suggest that DNA strands are anchored in a different conformation depending on the immobilization method employed. In order to avoid non-specific binding of target molecules, ethanolamine and inert proteins were assayed, and successful results were obtained when using small size proteins such as gelatine. Hybridization efficiency was around 20% for aminosilane-based immobilized probes, and more than 4-fold this value when the other immobilization methods were employed. The ability for recognition complementary DNA strands discriminating non-complementary ones was applied for species identification in mixtures. (J.L. López-Paz), [email protected] (M.Á. González-Martínez), [email protected] (J. Escorihuela), [email protected] (M.-J. Bañuls), [email protected] (R. Puchades), [email protected] (Á. Maquieira). 0925-4005/$ -see front matter
We demonstrate label-free molecule detection by using an integrated biosensor based on a Si 3 N4/... more We demonstrate label-free molecule detection by using an integrated biosensor based on a Si 3 N4/Si0 2 slotwaveguide microring resonator. Bovine serum albumin (BSA) and anti-BSA molecular binding events on the sensor surface are monitored through the measurement of resonant wavelength shifts with varying biomolecule concentrations. The biosensor exhibited sensitivities of 1.8 and 3.2 nm/(ng/mm 2 ) for the detection of anti-BSA and BSA, respectively. The estimated detection limits are 28 and 16 pg/mm 2 for anti-BSA and BSA, respectively, limited by wavelength resolution.
We report an experimental demonstration of single-strand DNA (ssDNA) detection at room temperatur... more We report an experimental demonstration of single-strand DNA (ssDNA) detection at room temperature using a photonic-crystal-waveguide-based optical sensor. The sensor surface was previously biofunctionalized with ssDNA probes to be used as specific target receptors. Our experiments showed that it is possible to detect these hybridization events using planar photonic-crystal structures, reaching an estimated detection limit as low as 19:8 nM for the detection of the complementary DNA strand.
In this letter, we present experimental results of antibody detection using a biosensor based on ... more In this letter, we present experimental results of antibody detection using a biosensor based on photonic bandgap structures, which are interrogated using a power-based readout technique. This interrogation method allows a realtime monitoring of the association process between the antigen probes and the target antibodies, allowing the instantaneous observation of any interaction event between molecules. because etunable lasers and optical spectrum analyzers are avoided for the readout, a drastic reduction of the final cost of the platform is obtained. Furthermore, the performance of the biosensing system is significantly enhanced due to the large number of data values obtained per second.
We report experimental results of label-free anti-bovine serum albumin (anti-BSA) antibody detect... more We report experimental results of label-free anti-bovine serum albumin (anti-BSA) antibody detection using a SOI planar photonic crystal waveguide previously bio-functionalized with complementary BSA antigen probes. Sharp fringes appearing in the slow-light regime near the edge of the guided band are used to perform the sensing. We have modeled the presence of these band edge fringes and demonstrated the possibility of using them for sensing purposes by performing refractive index variations detection, achieving a sensitivity of 174.8 nm/RIU. Then, label-free anti-BSA biosensing experiments have been carried out, estimating a surface mass density detection limit below 2.1 pg/mm 2 and a total mass detection limit below 0.2 fg.
The potential of thiol-ene chemistry as a selective strategy to functionalize silicon materials f... more The potential of thiol-ene chemistry as a selective strategy to functionalize silicon materials for DNA microarraying is demonstrated and applied to discriminate genetic variations.
The selective introduction of functional groups on the surface of silicon nitride/silicon oxide n... more The selective introduction of functional groups on the surface of silicon nitride/silicon oxide nanostructures was studied. Chemical strategies based on organosilane, Si-H and N-H reactivities were assayed. Among these strategies, the use of glutaraldehyde to selectively immobilize biomolecules only on the silicon nitride part of the chip surface was the most effective for the covalent attachment of proteins, maintaining also their bioavailability. The biomolecule surface coverage results up to 80% and the modification is selective versus silicon oxide; the biomolecule attaching only to silicon nitride and leaving the silicon oxide area of the device unmodified. The effectiveness of our novel selective surface modification procedure is also supported by comparing experimental and numerical calculations of the optical performance of a label-free optical ring resonator based on Si 3 N 4 /SiO 2 slot-waveguides.
In a previous work we introduced the term Bio-Photonic Sensing Cells (BICELLs), referred to perio... more In a previous work we introduced the term Bio-Photonic Sensing Cells (BICELLs), referred to periodic networks of nano-pillar suitable for biosensing when are vertically interrogated. In this article, we demonstrate the biosensing capabilities of a type of micrometric size BICELLs made of SU-8 nano-pillars fabricated over transparent substrates. We verify the biochips functionality comparing the theoretical simulations with the experimental results when are optically interrogated in transmission. We also demonstrate a sensitivity enhancement by reducing the pitch among nano-pillars from 800 to 700 nm. Thus, the Limit of Detection achievable in these types of BICELLs is in the order of 64 pg/mL for 700 nm in pitch among nano-pillars in comparison with 292 pg/mL for 800 nm in pitch when are interrogated by Fourier Transform Visible and Infrared Spectrometry. The experiments exhibited a good reproducibility with a relative standard deviation of 0.29% measured within 8 days for a specific concentration.
We developed biophotonic sensing arrays of 60 × 60 m 2 made of periodic lattices of high aspect r... more We developed biophotonic sensing arrays of 60 × 60 m 2 made of periodic lattices of high aspect ratio SU-8 nano-pillars in order to demonstrate their capability for label-free molecule detection, as well as the sensitivity enhancement in comparison with a single layer of SU-8. The biophotonic sensing arrays, that we call BICELLs (Biophotonic sensing cells), are interrogated vertically by using micron spot size Fourier transform visible and IR spectrometry (FT-VIS-IR). We monitored the surface immobilization of bovine serum albumin (BSA) antigen and anti-BSA antibody (aBSA) recognition. The bioassay exhibits a limit of detection (LOD) in the order of 2 ng/ml limited by the wavenumber uncertainty during the interrogation process. We also estimated and compared the theoretical biolayer thickness with previous results.
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Papers by María Bañuls