Multi-step surface functionalization of polyimide based evanescent wave photonic biosensors and application for DNA hybridization by Mach-Zehnder interferometer (original) (raw)

Fixation of DNA directly on optical waveguide surfaces for molecular probe biosensor development

Sensors and Actuators B: Chemical, 1995

Covalent attachment of DNA molecules to the surface of silicon nitride without an intermediate polymer layer is described. It is shown that the silicon nitride has a sorption capacity no less than 200 pg/mm 2, hybridization efficiency being close to 100%. The expected value of refractive index changes in the molecular layer under hybridization is estimated as sufficient for the operation of two kinds of waveguide-containing transducers.

Chemical silicon surface modification and bioreceptor attachment to develop competitive integrated photonic biosensors

Analytical and Bioanalytical Chemistry, 2012

Methodology for the functionalization of siliconbased materials employed for the development of photonic label-free nanobiosensors is reported. The studied functionalization based on organosilane chemistry allowed the direct attachment of biomolecules in a single step, maintaining their bioavailability. Using this immobilization approach in probe microarrays, successful specific detection of bacterial DNA is achieved, reaching hybridization sensitivities of 10 pM. The utility of the immobilization approach for the functionalization of label-free nanobiosensors based on photonic crystals and ring resonators was demonstrated using bovine serum albumin (BSA)/anti-BSA as a model system.

Functionalization of silicon dioxide and silicon nitride surfaces with aminosilanes for optical biosensing applications

Medical devices & sensors, 2020

The development of optical biosensors based on silicon dioxide or silicon nitride transducers requires the chemical activation of their surface to achieve stable, repeatable and homogeneous binding of biomolecules. In the present study, the chemical activation of silicon dioxide and silicon nitride surfaces with 3-aminopropyl-triethoxysilane (APTES) was optimized so as to enable the immobilization of biomolecules by adsorption or covalent bonding. Chemical activation was performed with either aqueous or organic solution of APTES and the surfaces were used to immobilize directly protein molecules by physical adsorption or further modified with glutaraldehyde to allow covalent binding of protein molecules. The protein immobilization capacity of the chemically activated silicon dioxide and silicon nitride surfaces was evaluated through incubation with mouse γ-globulins and reaction with a fluorescently labeled goat anti-mouse IgG antibody. By determining the surface fluorescence signal intensity, it was found that modification with 5% (v/v) APTES solution in ethanol followed by modification with glutaraldehyde provided 30% higher fluorescence signals than all the other protocols tested. In addition, this method provided the lower signal variation between different chips. To test the possible advantages of the chemical activation protocols for optical biosensing applications they were also applied to a label-free white light interference spectroscopy sensor and evaluated through a) real-time monitoring of the reaction between immobilized on the sensor surface mouse γ-globulins with an unlabeled goat antimouse IgG antibody and b) a non-competitive immunoassay for the determination of C-reactive protein. The results showed that in case of antibody, physical absorption provided marginally higher higher binding capacity to covalent bonding.

Development of surface chemistry for SPR based sensors for the detection of proteins and DNA molecules’

The immobilisation of biological recognition elements onto a sensor chip surface is a crucial step for the construction of biosensors. While some of the optical biosensors utilise silicon dioxide as the sensor surface, most of the biosensor surfaces are coated with metals for transduction of the signal. Biological recognition elements such as proteins can be adsorbed spontaneously on metal or silicon dioxide substrates but this may denature the molecule and can result in either activity reduction or loss. Self assembled monolayers (SAMs) provide an effective method to protect the biological recognition elements from the sensor surface, thereby providing ligand immobilisation that enables the repeated binding and regeneration cycles to be performed without losing the immobilised ligand, as well as additionally helping to minimise non-specific adsorption. Therefore, in this study different surface chemistries were constructed on SPR sensor chips to investigate protein and DNA immobilisation on Au surfaces. A cysteamine surface and 1%, 10% and 100% mercaptoundecanoic acid (MUDA) coatings with or without dendrimer modification were utilised to construct the various sensor surfaces used in this investigation. A higher response was obtained for NeutrAvidin immobilisation on dendrimer modified surfaces compared to MUDA and cysteamine layers, however, protein or DNA capture responses on the immobilised NeutrAvidin did not show a similar higher response when dendrimer modified surfaces were used.

Investigation into the effect that probe immobilisation method type has on the analytical signal of an EIS DNA biosensor

Biosensors and Bioelectronics, 2007

The analytical performance of an enhanced surface area electrolyte insulator semiconductor (EIS) device was investigated for DNA sensor development. The work endeavored to advance EIS performance by monitoring the effect of DNA probe layers have on the impedimetric signal during target hybridisation detection. Two universally employed covalent chemistries, direct and spacer-mediated attachment of amino modified probe molecules to amino-functionalised surfaces were investigated. Relative areal densities of immobilised probe were measured on planar and enhanced surface area substrates using epi-fluorescence microscopy. The reproducibility of the each immobilisation method was seen to have a direct effect on the reproducibility of the impedimetric signal. The sensitivity and selectivity was seen to be dependent on the type of immobilisation method. Real time, impedimetric detection of target DNA hybridisation concentrations as low as 25 and 1 nM were possible. The impact that probe concentration had on the impedimetric signal for selective and non-selective interactions was also investigated.

Gold and thiol surface functionalized integrated optical Mach–Zehnder interferometer for sensing purposes

Sensors and Actuators B-chemical, 1999

We demonstrate an integrated optical Mach-Zehnder interferometer for sensing purposes with a surface functionalized by thiols via an additional gold layer. Therefore, the oxidic silicon oxynitride waveguide surface was first covered by a thiol terminated silane self-assembled monolayer. An ultrathin gold layer was then deposited onto the ''active'' sulfur surface by OMCVD. This gold layer was finally functionalized by a biotinylated thiol in order to specifically bind streptavidin and a biotinylated antibody. Unspecific binding of streptavidin was tested also. q 1999 Elsevier Science S.A. All rights reserved.

Deposition of functionalized polymer layers in surface plasmon resonance immunosensors by in-situ polymerization in the evanescent wave field

Biosensors and Bioelectronics, 2009

Traditionally, the integration of sensing gel layers in Surface Plasmon Resonance (SPR) is achieved via "bulk" methods, such as precipitation, spin-coating or in-situ polymerization onto the total surface of the sensor chip, combined with covalent attachment of the antibody or receptor to the gel surface. This is wasteful in terms of materials as the sensing only occurs at the point of resonance interrogated by the laser. By isolating the sensing materials (antibodies, enzymes, aptamers, polymers, MIPs etc.) to this exact spot a more efficient use of these recognition elements will be achieved. Here we present a method for the in-situ formation of polymers, using the energy of the evanescent wave field on the surface of an SPR device, specifically localized at the point of interrogation. Using the photo-initiator couple of methylene blue (sensitizing dye) and sodium p-toluenesulfinate (reducing agent) we polymerized a mixture of N,N-methylene-bis-acrylamide and methacrylic acid in water at the focal point of SPR. No polymerization was seen in solution or at any other sites on the sensor surface. Varying parameters such as monomer concentration and exposure time allowed precise control over the polymer thickness (from 20 -200 nm). Standard coupling with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide

Recent Advances in Optical DNA Biosensors Technology

CHIMIA, 2005

Recent advances in nucleic acids-based biosensors have led to the development of DNA biosensors for DNA hybridisation detection and for nucleic acid–ligand binding studies. This review presents a concise description and an evaluation of the optical devices that have been employed in the development of optical DNA biosensors. Such optical devices include optical fibres, planar waveguide, surface plasmon resonance, resonant mirror and surface-enhanced Raman scattering. The specificity and response of each optical DNA biosensor are discussed. Overall, a rapid growth in the development of optical DNA biosensor technology will be seen in the near future, which will lead to the establishment of optical DNA biosensor technology as a major tool of analytical biochemistry.