Detection of bioagents using a shear horizontal surface acoustic wave biosensor
Inventors
Larson, Richard S • Hjelle, Brian • Hall, Pam R • Brown, David C • Bisoffi, Marco • Brozik, Susan M • Branch, Darren W • Edwards, Thayne L • Wheeler, David
Assignees
National Technology and Engineering Solutions of Sandia LLC • Sandia National Laboratories • UNM Rainforest Innovations
Publication Number
US-8709791-B2
Publication Date
2014-04-29
Expiration Date
2028-02-08
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Abstract
A biosensor combining the sensitivity of surface acoustic waves (SAW) generated at a frequency of 325 MHz with the specificity provided by antibodies and other ligands for the detection of viral agents. In a preferred embodiment, a lithium tantalate based SAW transducer with silicon dioxide waveguide sensor platform featuring three test and one reference delay lines was used to adsorb antibodies directed against Coxsackie virus B4 or the negative-stranded category A bioagent Sin Nombre virus (SNV). Rapid detection of increasing concentrations of viral particles was linear over a range of order of magnitude for both viruses, and the sensor's selectivity for its target was not compromised by the presence of confounding Herpes Simplex virus type 1 The biosensor was able to delect SNV at doses lower than the load of virus typically found in a human patient suffering from hantavirus cardiopulmonary syndrome (HCPS).
Core Innovation
The invention is a biosensor that combines the sensitivity of shear horizontal surface acoustic waves (SH-SAW) generated on a lithium tantalate (LiTaO3) piezoelectric material with the specificity of biological ligands such as antibodies for the detection of viral and other bioagents. The sensor surface is coated with a thin silicon dioxide layer which acts as a waveguide and supports the tethering of ligands, either covalently or non-covalently. When a bioagent binds to the ligand on the biosensor surface, a detectable change in the shear horizontal surface acoustic wave is produced, enabling qualitative and quantitative detection of the bioagent in a sample.
The biosensor operates at high frequencies, particularly around 325 MHz, and utilizes a sensor architecture featuring multiple delay lines for test and reference measurements. This setup, combined with surface chemistries enabling robust ligand tethering via methods including physisorption and chemisorption, allows rapid, specific detection of bioagents such as Coxsackie virus B4 and the Sin Nombre virus (SNV) with high sensitivity and selectivity, even in complex environmental samples. Detection is based on measuring phase shifts in the surface acoustic wave induced by ligand-bioagent binding.
The problem being addressed is the need for rapid, sensitive, and reliable detection of micro-organisms and bioagents relevant to bioterrorism, food safety, clinical diagnostics, and environmental monitoring. Existing detection methods often require sample preprocessing, are time-consuming, or lack portability. The invention solves these problems by providing a label-free, real-time biosensor capable of detecting a wide range of biological and chemical agents with high specificity and sensitivity, amenable to portable and field applications.
Claims Coverage
The patent contains independent claims describing methods for detecting bioagents using a ligand-based biosensor configured with a lithium tantalate piezoelectric material coated with silicon dioxide and producing high frequency shear-horizontal surface acoustic waves. The inventive features center on the biosensor composition, method of operation, and detection parameters.
Method for detecting bioagents using a ligand-based biosensor with lithium tantalate and silicon dioxide coating
A biosensor comprising biological ligands complexed to the surface of a lithium tantalate piezoelectric material coated with a thin silicon dioxide layer, capable of producing shear-horizontal surface acoustic waves in the range of about 275 to 400 MHz to detect binding of bioagents, specifically viruses, through changes in the acoustic wave.
Utilization of high frequency shear-horizontal surface acoustic waves for detection
Operating the biosensor at input frequencies specifically ranging from about 275 to 400 MHz (including preferred ranges of 315 to 400 MHz and 315 to 330 MHz), enabling sensitive detection of bioagent-ligand binding events via phase changes in the acoustic waves.
Ligand tethering on silicon dioxide layer via covalent or non-covalent bonding
The biological ligands, especially antibodies, are tethered to the silicon dioxide layer on the piezoelectric material surface by covalent or non-covalent methods, including physisorption onto hexamethyldisilazane layers, with the silicon dioxide layer thickness ranging from about 500 to 10,000 angstroms, produced by plasma enhanced chemical vapor deposition.
Method for detecting viral bioagents in environmental or human samples
Detection of viral bioagents such as HSV-1, Coxsackie virus, Sin Nombre virus, HIV 1 or 2, influenza viruses, respiratory syncytial virus, or hepatitis viruses, in samples including environmental or human fluids, by exposing the ligand-functionalized biosensor surface to the sample and detecting changes in high frequency shear-horizontal surface acoustic waves indicative of bioagent binding.
Phase shift detection as indicator of bioagent binding
Determining the presence of analytes by monitoring changes in the phase of the shear-horizontal surface acoustic waves generated on the biosensor surface when the bioagent binds to the tethered ligand.
The claims cover methods employing a lithium tantalate-based biosensor coated with silicon dioxide and functionalized with ligands, particularly antibodies, to detect viral bioagents through high frequency shear-horizontal surface acoustic wave measurements within defined frequency ranges, where analyte presence is indicated by phase changes in the acoustic waves following bioagent-ligand binding.
Stated Advantages
Rapid, real-time detection of viral agents within about 15 seconds and full signal stabilization within approximately 2 minutes.
High sensitivity allowing detection of bioagent concentrations significantly lower than levels found in infected human patients.
High specificity enabling discrimination between target bioagents and confounding agents without compromise of selectivity.
Capability to detect bioagents in complex environmental samples such as sewage effluent and river water without pre-processing.
Portability and suitability for field and real-world applications, including environmental surveillance and medical diagnostics.
Versatility for detection of a wide range of biological and chemical bioagents by selecting appropriate ligands tethered to the sensor surface.
Documented Applications
Detection of viral bioagents such as Coxsackie virus B4 and Sin Nombre virus in environmental water samples (e.g., sewage effluent, river water) and human samples (e.g., blood, serum, plasma, urine, sputum, fecal matter).
Monitoring and detection of bioagents related to bioterrorism, food poisoning, clinical diagnostics, and environmental surveillance applications.
Use in agricultural applications including the detection of plant viruses.
Field operations including portable, hand-held biosensor devices for on-site detection of bioagents.
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