How does Successive Proximity Extension Amplification Reaction (SPEAR) Technology Work?
SPEAR uses a novel two-factor authentication mechanism that employs two target-specific antibodies, each linked to a unique DNA device. One is primarily double-stranded with two toeholds; the other is single-stranded and carries a short sequence complementary to one toehold. Upon target binding, proximity enables hybridization and polymerase extension, adding a first extended sequence on the single-stranded DNA device.
A second hybridization-extension step occurs only when the probes remain co-localized for an extended period, creating an amplifiable DNA sequence.
The intrinsic specificity of this two-factor authentication eliminates the need for solid surface capture, minimizes background and non-specific signal, delivering unparalleled sensitivity and specificity. Target-specific signals are quantified through standard qPCR.
Parallel Plexing
As neurological research advances toward multi-analyte profiling, there is an increasing demand for high-performance, efficient solutions that can quantify multiple biomarkers from limited sample volumes. While this is a challenge for many multipleixing platforms, the SPEAR Platform enables up to four biomarkers to be run concurrently without compromising analytical performance. The SPEAR UltraDetect™ Parallel Plex Solution supports existing SPEAR UltraDetect™ Assay Kits, in combination with the SPEAR Reaction Kit, for concurrent analysis of two to four biomarkers in 96- and 384-well plate formats. Read this app note to learn more about the protocol.
SPEAR UltraDetect Assay Performance
Unparalleled Sensitivity with SPEAR UltraDetect™ pTau 231 Assay
The SPEAR UltraDetect pTau 231 Assay demonstrates unparalleled sensitivity, delivering high quantifiability – important for exploration of pTau 231 as an early marker in longitudinal studies and potential applications in clinical trials.
In a study comparing a cohort of PET-confirmed amyloid positive and amyloid negative patient samples, SPEAR UltraDetect pTau 231 Assay quantified 100% of samples – including amyloid negative samples with average CV of 5%.
SPEAR UltraDetect™ pTau 217
The SPEAR UltraDetect pTau217 testing on CSF-confirmed EDTA Plasma AD and non-AD (Control) including 48 non-AD and 40 AD. Amyloid PET confirmed EDTA plasma including 33 Amyloid negative (Control) and 28 Amyloid positive (AD).
Unparalleled Precision with the SPEAR UltraDetect™ GFAP Assay
The SPEAR UltraDetect GFAP Assay demonstrates unparalleled precision. Combined with 100% quantification of healthy samples, high precision is important for detected small changes in longitudinal and clinical trial studies.
Confirming this performance with clinical samples, including healthy controls and diseased patient samples, the SPEAR UltraDetect GFAP Assay quantified 100% of samples and achieved a mean replicate CV% of 3.0%
SPEAR Assay Workflow
The SPEAR solution is powered by homogeneous, two-factor authenticated assay technology with automated liquid handling, incubation, standard qPCR, and data analysis software.
- Assay & Reagent Kits SPEAR UltraDetect™ Assay Kits and companion Reaction Kit include all required reagents and easy-to-follow instructions for sample preparation and assay execution.
- Semi-Automated Assay Workflow The Formulatrix® F.A.S.T™ automates all critical pipetting steps, including a calibrator dilution series, sample dilution, and reagent additions.
- Readout and Data Analysis SPEAR’s unique two-factor authentication mechanism generates a true binding signal for readout on standard qPCR.
The easy-to-use SPEARview software transforms qPCR data into sample concentration results and provides seamless support across different qPCR formats.
