Description
Surface-functional biosensor recognition ligand designed for selective detection of Human Epidermal Growth Factor Receptor 2 (HER2), supplied as a thiol-modified DNA aptamer for direct immobilization on gold and thiol-reactive sensor surfaces. Engineered for controlled probe orientation, high binding specificity, and stable integration into electrochemical and microfluidic biosensor platforms. For Research Use Only (RUO).
Product Description
The ProbeSeq Human Epidermal Growth Factor Receptor 2 BiosensorProbe™ is a thiol-functionalized single-stranded DNA aptamer engineered for selective recognition and capture of HER2, a transmembrane receptor tyrosine kinase widely used as a biomarker for cancer diagnosis, prognosis, and therapeutic monitoring. The probe incorporates a terminal sulfhydryl (–SH) functional group enabling controlled covalent immobilization on gold and thiol-reactive sensor interfaces while preserving aptamer folding and target-binding activity.
HER2 is a membrane-associated glycoprotein receptor (~185 kDa) belonging to the ErbB receptor family and is overexpressed in multiple cancers including breast, gastric, and ovarian cancers. Circulating extracellular HER2 domain levels typically range from 5–15 ng/mL in healthy individuals and may exceed >30–100 ng/mL in HER2-positive malignancies. The BiosensorProbe™ enables sensitive surface-based detection across clinically relevant concentration ranges.
The probe is optimized for surface-immobilized sensing environments, enabling dense probe packing (~10¹²–10¹³ molecules/cm² on gold surfaces), controlled orientation, and stable signal generation across electrochemical, optical, and impedance-based detection platforms.
Recognition Mechanism
Target recognition is mediated by a sequence-engineered single-stranded DNA aptamer (~40–80 nucleotides) that undergoes conformational folding upon interaction with HER2 extracellular domain epitopes. Binding occurs through electrostatic interactions, hydrogen bonding, and molecular shape complementarity.
Typical equilibrium dissociation constant (Kd): 0.1–3 nM
Association kinetics: rapid binding within seconds to minutes
Detection capability: pg/mL to ng/mL range depending on sensor platform
The aptamer provides reversible binding suitable for quantitative biosensing and real-time monitoring applications.
Specificity and Selectivity
The HER2 BiosensorProbe™ demonstrates high molecular specificity toward HER2 with minimal cross-reactivity toward related receptor proteins including EGFR (HER1), HER3, and HER4.
Cross-reactivity: <3% against related ErbB family receptors
Non-specific adsorption reduction: >90% compared to non-functionalized DNA controls
Matrix compatibility: serum, plasma, cell lysates, and extracellular vesicle samples
Sequence-driven recognition targets HER2-specific structural epitopes enabling selective detection in complex biological samples.
Molecular Format and Functionalization
Synthetic single-stranded DNA aptamer containing terminal thiol (–SH) functional group introduced via controlled chemical modification.
Aptamer length: ~40–80 nucleotides
Functional group incorporation: ≥95% thiol modification
Purity: ≥95% (HPLC verified)
End modification: 5′ or 3′ thiol linker (C6 or equivalent)
The probe is chemically stabilized to preserve structural folding and functional group reactivity.
Surface Immobilization Chemistry
The terminal thiol group supports direct immobilization on gold electrodes through formation of self-assembled monolayers via Au–S bonding.
Surface binding strength: ~40–50 kcal/mol Au–S interaction
Typical immobilization time: 30–120 min
Recommended surface density: 1–10 pmol/cm²
Operating pH range after immobilization: 6.5–8.5
Compatible with nanostructured gold, planar gold electrodes, gold nanoparticles, and maleimide-functionalized surfaces.
Compatible Sensor Surfaces
Gold electrodes and nanostructured gold substrates
Gold nanoparticle-modified interfaces
Thiol-reactive polymer coatings
Maleimide-functionalized surfaces
Electrochemical impedance and amperometric sensors
Microfluidic lab-on-chip platforms
Liquid biopsy sensing systems
Performance Characteristics
Binding affinity (Kd): 0.1–3 nM
Surface coverage: 10¹²–10¹³ molecules/cm²
Operating temperature range: 4–45°C
Low non-specific adsorption on gold surfaces
Stable signal response over repeated measurement cycles
Stability
The HER2 BiosensorProbe™ is chemically stabilized to maintain aptamer conformation and thiol reactivity.
Shelf stability: ≥12 months at −20°C
Working stability after immobilization: ≥7–14 days depending on surface conditions
Thermal stability: stable up to ~60°C for short exposure
Storage
Store at −20°C in supplied buffered formulation (10 mM Tris, 1 mM EDTA, pH 7.4 or equivalent). Avoid repeated freeze–thaw cycles and prolonged exposure to oxidizing conditions. Store protected from light.
Applications
Cancer biomarker detection
HER2-positive tumor monitoring
Liquid biopsy research
Electrochemical biosensor development
Microfluidic diagnostic devices
Oncology biomarker panels
Extracellular vesicle and circulating protein analysis
