Description
Surface-functional biosensor recognition ligand designed for selective detection of Prostate Specific Antigen (PSA), supplied as a thiol-modified DNA aptamer for direct immobilization on gold and thiol-reactive sensor surfaces. Engineered for controlled orientation, high binding specificity, and stable integration into electrochemical and microfluidic biosensor platforms. For Research Use Only (RUO).
Product Description
The ProbeSeq Prostate Specific Antigen BiosensorProbe™ is a thiol-functionalized single-stranded DNA aptamer engineered for selective recognition and capture of Prostate Specific Antigen (PSA), a clinically relevant serine protease biomarker used for prostate cancer screening and disease 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.
Prostate Specific Antigen is a glycoprotein enzyme with molecular weight ~33–34 kDa secreted by prostate epithelial cells. PSA levels in healthy serum typically range from 0–4 ng/mL and may increase above 10–100 ng/mL in disease conditions. The BiosensorProbe™ enables sensitive surface-based detection across clinically relevant PSA 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 (~35–60 nucleotides) that undergoes conformational folding upon interaction with structural domains of PSA. Binding occurs through electrostatic interactions, hydrogen bonding, and molecular shape complementarity.
Typical equilibrium dissociation constant (Kd): 0.1–5 nM
Association kinetics: rapid binding within seconds to minutes depending on surface density
Detection capability: ng/mL to pg/mL range depending on sensor platform
The aptamer maintains structural integrity following immobilization and provides reversible binding suitable for quantitative biosensing.
Specificity and Selectivity
The PSA BiosensorProbe™ demonstrates high molecular specificity toward PSA with minimal cross-reactivity toward related serine proteases including kallikrein family proteins, trypsin-like proteases, and abundant serum proteins.
Cross-reactivity: <5% against related serum proteases under physiological conditions
Non-specific adsorption reduction: >90% compared to non-functionalized DNA controls
Matrix compatibility: serum, plasma, and whole blood extracts
Sequence-driven recognition targets conformational epitopes unique to PSA, enabling selective detection in complex biological samples.
Molecular Format and Functionalization
Synthetic single-stranded DNA aptamer with terminal thiol (–SH) functional group introduced via controlled chemical modification.
Molecular length: ~12–20 kDa equivalent mass
Functional group density: ≥95% thiol incorporation
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
Compatible with nanostructured gold, planar gold electrodes, gold nanoparticles, and maleimide-functionalized surfaces.
Immobilized probes remain stable under repeated assay cycles and physiological buffer conditions (pH 6.5–8.0).
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
Surface plasmon resonance gold chips
Performance Characteristics
Binding affinity (Kd): 0.1–5 nM
Surface coverage: 10¹²–10¹³ molecules/cm²
Operating pH range: 6.5–8.5
Operating temperature range: 4–45°C
Low non-specific adsorption on gold surfaces
Stable signal response over repeated measurement cycles
Stability
The PSA 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
Nuclease resistance: moderate (recommended use in controlled buffers or treated samples)
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 exposure to oxidizing conditions to preserve thiol functionality. Store protected from light and air exposure.
Applications
Cancer biomarker detection
Prostate cancer screening research
Electrochemical biosensor development
Microfluidic diagnostic device engineering
Surface plasmon resonance assays
Wearable sensing systems
Multiplex oncology biomarker panels
