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Electrochemical / Redox-Active Modified Bases

Harnessing Redox Chemistry for Advancing Biosensing and therapeutid Applications

Attach redox tags such as Ferrocene, Methylene Blue, Anthraquinone, and Viologen to DNA/RNA for voltammetry, amperometry, and redox-switchable sensing. Offered as NHS, azide/alkyne, maleimide, or ready-made nucleoside analogs (e.g., Fc-dT).

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Overview Redox-Active Linkers Design & QC Related Services Related Services

Redox-Active Modified Bases — How They Work

Redox-active modifications introduce electrochemically active functional groups to oligonucleotides, enabling highly specific, label-integrated detection of nucleic acids, proteins, and small molecules—including drugs and metabolites. These sensors operate via target-induced folding or unfolding of an electrode-bound oligonucleotide probe, which alters electron-transfer efficiency upon analyte binding.

Common Platforms

  • E-DNA (Electrochemical DNA sensors): Detect hybridization events with complementary DNA/RNA sequences.
  • E-AB (Electrochemical Aptamer-Based sensors): Use aptamers to selectively bind proteins or small-molecule targets.

In both platforms, the oligonucleotide is typically labeled with a redox-active reporter (e.g., ferrocene or methylene blue) at one terminus and immobilized onto a gold electrode via a thiol–gold bond at the other. Target binding induces conformational changes that modulate redox signal intensity, enabling sensitive, real-time detection—even in complex matrices such as serum or soil.

Examples of Redox-Active Linkers in Oligo Modifications

Representative options; additional variants and custom linkers available on request.

Hide Products & Notes
Product Description Function Application Code
Ferrocene (Fc)-C6 Iron-containing metallocene Reversible redox reporter Stable redox tag; sensor calibration [Fc-C6]
Ferrocene-3′ Iron-containing metallocene Redox reporter (3′ placement) Signal-on/off DNA sensors [Fc-3′]
Ferrocene-dT Metallocene-modified dT Internal redox base Base-embedded reporter for probes [Fc-dT]
Ferrocene-NHS Activated ester Amino-conjugatable redox tag Post-synthetic Fc labeling [Fc-NHS]
Methylene Blue (MB2-Azide) Phenothiazine dye Electron-transfer mediator Common in electrochemical DNA sensors [MB2-N3]
Methylene Blue II Phenothiazine dye Redox reporter Electrochemical hybridization assays [MB2-II]
Methylene Blue Mal (MB2-Mal) Phenothiazine dye Maleimide-thiol coupling Thiol-directed MB labeling [MB2-Mal]
Methylene Blue MB2-NHS Phenothiazine dye Amino-coupling reporter 5′-Amine, internal amine labeling [MB2-NHS]
Anthraquinone-C2-dT Quinone Strong redox activity Robust voltammetric detection [AQ-dT]
Nitrobenzene Aromatic nitro group Electron-accepting tag Low-overpotential sensing schemes [NBz]
Thionine Phenothiazine Low-potential mediator Low-bias electrochemical readout [Thio]
Viologen Derivatives Bipyridinium Redox-switchable label Controlled signal generation [Viologen]
Disulfide Linkers –S–S– Reductive cleavage handle Releasable/electro-cleavable constructs [SS]
Technical Notes
  • Operating potential: MB/Thionine work at lower potentials; Ferrocene near +0.4–0.5 V vs Ag/AgCl; Viologens provide reversible multi-electron waves.
  • Placement: 3′/5′ tags give robust signals on flexible linkers; internal Fc-dT/AQ-dT preserve duplex geometry with defined electron distance.
  • Linkers: Use short PEG/spacers (C3–C12) to tune electron transfer without quenching hybridization.
  • Buffers: Avoid excess chelators/redox-active contaminants; oxygen removal may improve S/N for some systems.
  • QC: Identity by ESI-MS; purity by HPLC; optional voltammetric fingerprint or spectroscopic confirmation of tag loading.

Need a specific redox potential or custom handle (alkyne/azide/amine/thiol)? We can source or synthesize to spec.

Custom Redox-Conjugation Options

We offer site-specific conjugation of redox-active groups to DNA, RNA, and LNA oligonucleotides, with compatibility across:

  • Amine-modified oligos
  • Thiol-modified oligos
  • Click chemistry-ready azide or alkyne handles
  • PEG spacers to reduce steric hindrance
  • Bifunctional linkers such as EMCH
  • Redox and fluorescent dye combinations for FRET-based signal enhancement

Key Features and Applications

  • Electrochemical Biosensors: Enable precise, real-time detection via redox signaling.
  • Redox-Responsive Drug Delivery: Trigger oligo-drug release in reducing or oxidizing environments (e.g., tumor microenvironments).
  • Molecular Probes: Support detection of nucleic acid interactions through redox-labeled hybridization events.
  • Surface Immobilization: Facilitate covalent attachment to conductive surfaces like gold or carbon electrodes.

Design & QC

Design Tips

  • Assay first: Pick tag by potential window and desired signal direction (signal-on vs signal-off).
  • Spacer length: Start with C6–C12 or short PEG; adjust to optimize electron transfer vs duplex stability.
  • Site selection: Prefer termini to minimize Tm impact; for internal tags use analogs like Fc-dT/AQ-dT.
  • Multiplex: Combine tags with separable peaks (e.g., MB + Fc) for dual-channel readouts.

QC & Documentation

  • ESI-MS identity (apo and, if applicable, metal-bound states).
  • HPLC purity; optional SEC for larger conjugates.
  • Functional check: differential pulse/ square-wave voltammetry trace (optional).
  • CoA: yield (OD/µmol), purity %, linker and tag details, counter-ions.

Speak to a Scientist

Tell us about your electrochemical probe

Full Name *
Email *
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Oligo Type
Redox Tag & Placement
Linker / Spacer
Assay & Potential Window
Purification
QC Requirements
Scale / Quantity
Timeline
Project Summary *Please avoid confidential details; we can arrange an NDA if needed.

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