a s2mall molecule or hapten covalently attached to an oligonucleotide that allows it to be selectively recognized, captured, or pulled down using a high-affinity binding partner

Enhance stability, block exonuclease digestion or enable downstream conjugation at the 5′ or 3′ end. (e.g. dd-dC, spacer, 3' phosphate, Inverted dT)

Linkers are designed either to break under specific (e.g., photocleavable linkers)—or to form permanent covalent bonds that stably connect the oligo to its cargo (e.g., thioether bonds).

Lipids such as cholesterol, fatty acids, or phospholipids are hydrophobic, which helps the oligo to attach to cell membranes, improve cell entry, and enhance delivery.

Attach functional tags for Real-time detection (qPCR), imaging, affinity capture, or redox-based detection. (e.g. Alexa, FAM, HEX, CY3, Cy5, ATTO, Methylene Blue, Biotin/Dig)

A reactive modifier is a chemical handle (often at the 5′, 3′ end or internal base/sugar) that allows the oligo to be conjugated, crosslinked, immobilized, or labeled via specific chemistries.

To improve hybridization, mismatch tolerance, or structural control. (e.g. 5-Methyl-dC, Inosine, Benner bases (Z/P), 2-Aminopurine, Psoralen, Azobenzene, 5-Bromo-dU)

Facilitate metal ion binding for radiolabeling, imaging, or purification. (e.g. DOTA, NOTA, TETA, DTPA, NTA, CB-TE2A)

Enable covalent attachment to other biomolecules, drugs for drug delivery, targeting, protein/antibody conjugation (e.g. PEG, SMCC, Maleimide, GalNAc, Doxorubicin, Antibody)

Redox modified oligos enable electron transfer in response to binding or structural changes. These modifications are used in biosensors, diagnostic, and electrochemical detection platform. (e.g. Ferrocene, Methylene Blue)

Linkers and spacers are essential for optimizing the structure, flexibility, and functionality of modified oligonucleotides. They help reduce steric hindrance, improve hybridization efficiency.

Modify the ribose or deoxyribose sugar to enhance binding affinity, increase stability, alter conformation (e.g. 2'-OMe, LNA, UNA, HNA, TNA, Morpholino, GNA)

For improving nuclease resistance, charge modulation and structural integrity. (e.g. Phosphorothioate (PS), Morpholino (PMO), Phosphoramidate (PN))

Emits visible light during a chemical reaction allowing for sensitive detection without the need for external light excitation. (e.g. Acridine, HRP and AP)

Oligo modified with branched or multivalent structures to increase payload capacity, signal intensity, or functional complexity (e.g. dual-arm brancher, dendrimer core).

Multifunctional molecules that link molecular recognition (via the oligo) with enzymatic activity, enabling powerful applications in diagnostics, molecular biology, and targeted delivery. (e.g. HRP, AP conjugates)

An essential component in dual-labeled oligonucleotide probes used for qPCR, FRET assays, and other real-time detection applications. (e.g. BHQ, Dabcyl, Eclipse)

m⁷GpppG, CleanCap, Cap 1, or NAD caps can be chemically or enzymatically added to the 5′ end of RNA oligonucleotides. These cap analogs are designed to promote efficient ribosome recruitment during translation.