Description
Surface-functional biosensor recognition ligand designed for selective detection of phosphorylated Tau 181 (pTau181), supplied as a carboxyl-modified DNA aptamer for covalent immobilization onto amine-functionalized sensor surfaces using EDC/NHS chemistry. Engineered for stable probe orientation, high binding specificity, and long-term integration into electrochemical and microfluidic biosensor platforms. For Research Use Only (RUO).
Product Description
The ProbeSeq Phosphorylated Tau 181 BiosensorProbe™ is a carboxyl-functionalized single-stranded DNA aptamer engineered for selective recognition and capture of tau protein phosphorylated at threonine 181, a highly specific biomarker of Alzheimer’s disease pathology and neurodegenerative progression. The probe incorporates a terminal carboxyl (–COOH) functional group enabling covalent amide bond formation with primary amine-functionalized sensor surfaces via carbodiimide (EDC/NHS) activation.
pTau181 is a post-translationally modified tau isoform (~45–65 kDa) associated with neurofibrillary tangle formation and synaptic dysfunction. Baseline plasma levels are typically <1 pg/mL and may increase to >10–60 pg/mL in Alzheimer’s disease. The BiosensorProbe™ supports ultrasensitive detection across clinically relevant concentration ranges.
The probe enables stable covalent surface attachment, controlled probe orientation, and high surface density (~10¹² molecules/cm²) for reproducible biosensor performance.
Recognition Mechanism
Target recognition is mediated by a sequence-engineered single-stranded DNA aptamer (~45–85 nucleotides) forming a selective binding structure that recognizes phosphorylation-specific epitopes of tau protein.
Binding affinity (Kd): 0.01–0.5 nM
Detection range: sub-pg/mL to ng/mL
Association kinetics: seconds to minutes
Phosphorylation-site selective recognition
Specificity and Selectivity
The pTau181 BiosensorProbe™ demonstrates strong selectivity for tau phosphorylated at Thr181 with minimal cross-reactivity toward total tau, other tau isoforms, and unrelated neuronal proteins.
Cross-reactivity: <2% vs total tau and other phospho-sites
Non-specific adsorption reduction: >90%
Matrix compatibility: plasma, serum, cerebrospinal fluid
Molecular Format and Functionalization
Synthetic single-stranded DNA aptamer containing terminal carboxyl functional group.
Aptamer length: ~45–85 nucleotides
Functionalization efficiency: ≥95% COOH incorporation
Purity: ≥95% (HPLC verified)
End modification: 5′ C6-carboxyl linker
Buffer formulation: nuclease-free buffered solution
Surface Immobilization Chemistry
Carboxyl group enables covalent amide bond formation with amine-functional surfaces.
Activation chemistry: EDC/NHS coupling
Coupling efficiency: >85%
Bond type: covalent amide linkage
Immobilization time: 20–60 min
Operating pH after immobilization: 6.0–8.0
High stability under flow and repeated measurement
Compatible Sensor Surfaces
Amine-functionalized polymer surfaces
Aminated graphene and carbon electrodes
Silicon oxide and glass surfaces
Microfluidic polymer chips
Hydrogel biosensors
Paper-based analytical devices
Performance Characteristics
Binding affinity: 0.01–0.5 nM
Surface coverage: ~10¹² molecules/cm²
Operating temperature: 4–45°C
Low probe desorption
Stable signal response
Stability
Shelf stability: ≥12 months at −20°C
Working stability after immobilization: ≥21 days
Resistant to shear and washing cycles
Storage
Store at −20°C in supplied buffer. Avoid repeated freeze–thaw cycles. Protect from light.
Applications
Alzheimer’s disease diagnostics research
Neurodegeneration monitoring
Disease progression studies
Drug screening platforms
Electrochemical biosensor development
Microfluidic neurological diagnostics
