Polymer films with size-selected silver nanoparticles as plasmon resonance-based transducers for protein sensing (original) (raw)
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Colloids and Surfaces B-biointerfaces, 2011
To perform biosensing using nanoparticles in solution, silver particles were coated with bovine serum albumin (BSA) and polyvinyl alcohol (PVA) as control stabilizer. The plasmon resonance (420 nm) of the silver nanoparticles in solution was shifted slightly to longer wavelength (443 nm) when they were coated with BSA. The biointeractions of these engineered nanoparticles were studied using a mouse model. No significant changes in behavior or toxicity were observed. The nanoparticles were detected in all tissues including the brain. Antibody recognition was monitored via the change in light absorption which accompanied binding, indicating that the particles can be used as a biosensor to gain more insight into cellular mechanisms governing the function of organs in general, and the blood brain barrier (BBB) and brain in particular.► To perform biosensing using nanoparticles in solution, the metal particles were coated with protein BSA and PVA as control stabilizer. ► Biocompatability study were carried out in mouse model and found no immunological and toxicity effect. The silver nanoparticles were distributed in all organs including brain. ► Functionalized silver nanoparticles with protein can be used as affinity probes in trapping antiBSA in this study or any molecule from aqueous solutions through SPR.
Triangular silver nanoparticles (∼100 nm wide and 50 nm high) have remarkable optical properties. In particular, the peak extinction wavelength, λmax of their localized surface plasmon resonance (LSPR) spectrum is unexpectedly sensitive to nanoparticle size, shape, and local (∼10-30 nm) external dielectric environment. This sensitivity of the LSPR λmax to the nanoenvironment has allowed us to develop a new class of nanoscale affinity biosensors. The essential characteristics and operational principles of these LSPR nanobiosensors will be illustrated using the well-studied biotin-streptavidin system. Exposure of biotin-functionalized Ag nanotriangles to 100 nM streptavidin (SA) caused a 27.0 nm red-shift in the LSPR λmax. The LSPR λmax shift, ∆R/∆Rmax, versus [SA] response curve was measured over the concentration range 10 -15 M < [SA] < 10 -6 M. Comparison of the data with the theoretical normalized response expected for 1:1 binding of a ligand to a multivalent receptor with different sites but invariant affinities yielded approximate values for the saturation response, ∆Rmax ) 26.5 nm, and the surface-confined thermodynamic binding constant Ka,surf ) 10 11 M -1 . At present, the limit of detection (LOD) for the LSPR nanobiosensor is found to be in the low-picomolar to high-femtomolar region. A strategy to amplify the response of the LSPR nanobiosensor using biotinylated Au colloids and thereby further improve the LOD is demonstrated. Several control experiments were performed to define the LSPR nanobiosensor's response to nonspecific binding as well as to demonstrate its response to the specific binding of another protein. These include the following: (1) electrostatic binding of SA to a nonbiotinylated surface, (2) nonspecific interactions of prebiotinylated SA to a biotinylated surface, (3) nonspecific interactions of bovine serum albumin to a biotinylated surface, and (4) specific binding of anti-biotin to a biotinylated surface. The LSPR nanobiosensor provides a pathway to ultrasensitive biodetection experiments with extremely simple, small, light, robust, low-cost instrumentation that will greatly facilitate field-portable environmental or point-of-service medical diagnostic applications.
Advanced Materials Letters
Silicon is an excellent material for sensing. Sensors for all signal domains can be realised, and in many cases, integrated with read-out electronics. However, in some applications an addition layer may be required for sensing and/or to protect the silicon device. Piezoelectric, polymers or magneto resistive layers can be added to expand the options of silicon. In the case of some implants, the polymer is used to protect the body from the device. In harsh chemical environments, the coating layer can be used to protect the silicon and in some cases also function as the sensor. Layers such as SiC represent a chemically resilient layer to protect the layers below, but this layer can also be used as a sensing layer. Atomic layer deposition (ALD) provides thin uniform, and pinhole free layers which can be used as protection and sensing. Other materials include graphene. In cases such as extreme temperature, it is more difficult to protect the silicon device, and in these cases the electronics must be isolated from the heat. This paper will show examples of how coating layers can enhance the sensing capabilities of silicon devices and also provide protection.
J Nanophotonics, 2013
The nanofabrication and surface modification of a transducer based on localized surface plasmon resonance (LSPR) of gold nanostructure arrays for biosensing was studied. We used electron beam lithography for the nanopatterning technique, which let us choose LSPR sensor properties by providing immense control over nanostructural geometry. A critical step in the utilization of this transducer is to form a selective biolayer over the gold nanostructures. We applied plasma polymerization and wet chemistry techniques for ethylenediamine (EDA) modification and glutaraldehyde immobilization as intermediate layers, respectively. The gold nanostructure arrays were primarily modified using EDA in order to activate the surface with amine groups that are cross-linked with later added avidin molecules by the help of glutaraldhyde layer residing in between. The success of plasma polymerization was validated with x-ray photoelectron spectroscopy measurements. As a last step, we introduced biotin to the surface (biotin has a high affinity for avidin). We were able to detect the LSPR resonance wavelength shift in the transmission spectra at each step of modification, including the avidin-biotin interaction, which acts as a model for specific molecule detection using LSPR.
Biosensors & Bioelectronics, 1998
Surface plasmon resonance (SPR) biosensors were constructed on miniature integrated sensors. Recognition elements were attached to the sensor surface using a gold-binding repeating polypeptide. Biosensors with fluorescyl groups attached to their surfaces were functional for at least 1 month of daily use with little decrease in response to the binding of an anti-fluorescyl monoclonal antibody. The coupling of protein A to the gold-binding polypeptide on the sensor surface enabled the biosensor to detect the binding of antibodies to the protein A and provided a sensor with convertible specificity. The system described herein provides a simple and rapid approach for the fabrication of highly specific, durable, portable and low cost SPR-based biosensors.
Size-selected silver clusters on polymer surfaces as plasmonic transducers for nano-biosensors
2017
, who not only assisted me with some steps of the fabrication and characterization process, but also helped me to overcome all the hardships found during the experiments. To Professor Dr. Ana G. Silva, I would like to express my sincere gratitude. Thank you very much for the opportunity to do this thesis, for all the encouragement and support, for sharing all the knowledge in the long scientific discussions, the advices in all moments and the lovely week passed in Aalborg. I would like to thank my friends for the support and motivation throughout my university years. To Pedro and Sofia who were with me since the beginning, to Flávia and Marta for the funny moments and support throughout these years (Pump the Jam!). To Mafalda and Lola, two stranger girls who shared a house with me in Aalborg, but since then they never left. And to Ricardo, the special guy who opened the door. Without them, these last years surely would not have been as fun as they were. Finally, and most importantly, I would like to thank my family, my grandmothers Zica and Antónia, my uncle Miguel, my sister Carolina and specially my Mom and Dad.
Key Engineering Materials, 2013
ABSTRACT The nanofabrication and surface modification of a transducer based on localized surface plasmon resonance (LSPR) of gold nanostructure arrays for biosensing was studied. We used electron beam lithography for the nanopatterning technique, which let us choose LSPR sensor properties by providing immense control over nanostructural geometry. A critical step in the utilization of this transducer is to form a selective biolayer over the gold nanostructures. We applied plasma polymerization and wet chemistry techniques for ethylenediamine (EDA) modification and glutaraldehyde immobilization as intermediate layers, respectively. The gold nanostructure arrays were primarily modified using EDA in order to activate the surface with amine groups that are cross-linked with later added avidin molecules by the help of glutaraldhyde layer residing in between. The success of plasma polymerization was validated with x-ray photoelectron spectroscopy measurements. As a last step, we introduced biotin to the surface (biotin has a high affinity for avidin). We were able to detect the LSPR resonance wavelength shift in the transmission spectra at each step of modification, including the avidin-biotin interaction, which acts as a model for specific molecule detection using LSPR.
Supported silver clusters as nanoplasmonic transducers for protein sensing
Sensors and Actuators B: Chemical, 2015
Transducers for optical sensing of proteins are prepared using cluster beam deposition on quartz substrates. Surface plasmon resonance phenomenon of the supported silver clusters is used for the detection. It is shown that surface immobilisation procedure providing adhesion of the silver clusters to quartz and functionalisation of cluster surfaces for antibody coupling are the key issues for cluster stability and protein detection. Focus was put on these tasks and the processes have been optimised. In particular, conditions for coupling of the antibodies to the clusters are developed providing an enhancement of the plasmon absorption band used for the detection. Atomic force microscopy study allows to suggest that immobilisation of antibodies on silver clusters has been achieved, thus giving a possibility to incubate and detect an antigen of interest. Hence, by applying the developed preparation stages and protein immobilisation scheme the sensing of protein of interest can be assured using a relatively simple optical spectroscopy method.
Modified Nanoparticle Films for Transmission Plasmon Biosensing
2007
The principle of the Transmission Plasmon Biosensor (TPB) is based on the Localized Surface Plasmon Resonance (LSPR) properties of noble metal nanoparticles attached to a transparent substrate. When the analyte of interest binds to the biological receptor molecules immobilized onto these nanoparticles, the absorption of the nanoparticles will change due to local changes in the refractive index (RI). In this study, we investigated various parameters in order to increase the final sensitivity of the TPB such as the deposition method, the size, the material and the (bio)functionality of the nanoparticles. For biosensing applications, the nanoparticles were further functionalized with the desired biological receptor molecules (e.g. antibodies or ampicillin) using mixed SelfAssembled Monolayers (SAMs) [1]. In this paper, the experimental results on the modification and the characterization of the nanoparticle films will be presented together with the preliminary results on biological sen...