2'-Fluoro-Arabino Nucleic Acid, FANA
FANA (2′-Fluoro-Arabino Nucleic Acid) is a synthetic sugar-modified xeno nucleic acid (XNA) in which the natural pentose sugar is replaced with 2′-deoxy-2′-fluoro-β-D-arabinose while retaining the natural nucleobases adenine (A), cytosine (C), guanine (G), thymine (T), or uracil (U). Unlike a modified nucleobase, FANA alters the sugar component of the nucleotide, providing enhanced physicochemical and biological properties while preserving standard Watson–Crick base pairing.
The introduction of fluorine at the 2′ position in the arabino configuration can improve oligonucleotide performance by increasing resistance to nuclease degradation and enhancing hybridization affinity toward complementary RNA. Compared with unmodified DNA, FANA-containing oligonucleotides can provide greater duplex stability, although the magnitude of the effect depends on the sequence, neighboring residues, target type, and modification pattern.
FANA is an important chemistry for antisense oligonucleotide (ASO) development because it combines strong RNA affinity with enhanced biological stability. When incorporated into appropriately designed chimeric gapmers, FANA residues can improve target recognition while preserving a central DNA region that supports RNase H-mediated cleavage. RNase H activity depends on the architecture of the construct, including the length and composition of the DNA gap and the placement of FANA residues.
In addition to antisense applications, FANA has demonstrated utility in aptamer engineering, XNA evolution, molecular diagnostics, biosensors, synthetic biology, genome-engineering research, and RNA-targeting technologies. The chemistry maintains predictable Watson–Crick recognition while providing improved resistance to exonucleases and endonucleases, making FANA-modified oligonucleotides useful in demanding biological environments and extended-duration experiments.
Bio-Synthesis offers custom FANA-modified oligonucleotides prepared using automated solid-phase phosphoramidite synthesis. Available monomers may include FANA-A (faA), FANA-C (faC), FANA-G (faG), FANA-T (faT), and FANA-U (faU), depending on project requirements and reagent availability. These monomers can be used to prepare fully modified FANA oligonucleotides, DNA/FANA chimeras, phosphorothioate gapmers, aptamers, molecular probes, and other advanced XNA constructs.
FANA chemistry may also be combined with phosphorothioate linkages, fluorescent dyes, quenchers, affinity labels, conjugation handles, and other compatible oligonucleotide modifications. Sequence design, modification placement, purification, analytical characterization, and final formulation can be customized according to the intended research application.
Typical Applications
- Antisense oligonucleotides and RNase H-active gapmers
- RNA knockdown and target-validation studies
- RNA-targeted therapeutic research
- Aptamer discovery and optimization
- XNA evolution and synthetic biology
- Genome-engineering and CRISPR-related research
- Molecular diagnostics and hybridization probes
- Biosensors and affinity-based assays
- Nuclease-resistant research oligonucleotides
- Custom DNA/FANA and RNA/FANA chimeric constructs
Specifications & Technical Notes
| Property |
Specification / Notes |
| Modification |
FANA (2′-Fluoro-Arabino Nucleic Acid) |
| Chemistry Classification |
Sugar-modified xeno nucleic acid (XNA) |
| Sugar Modification |
2′-Deoxy-2′-fluoro-β-D-arabinose |
| Available Bases |
FANA-A (faA), FANA-C (faC), FANA-G (faG), FANA-T (faT), and FANA-U (faU), subject to project requirements and reagent availability |
| Backbone Compatibility |
Phosphodiester and phosphorothioate backbones; other mixed-backbone designs may be evaluated individually |
| Synthesis Method |
Automated solid-phase phosphoramidite synthesis |
| Hybridization Affinity |
Generally provides stronger binding to complementary RNA than unmodified DNA; the effect is sequence- and design-dependent |
| Duplex Stability |
Can increase duplex melting temperature (Tm) relative to DNA; the magnitude depends on sequence, target type, and FANA placement |
| Nuclease Resistance |
Enhanced resistance to nuclease degradation compared with unmodified DNA |
| RNase H Compatibility |
FANA can be used in appropriately designed chimeric antisense constructs. RNase H activity depends on the length and composition of the central DNA gap and the placement of modified residues |
| Compatible Oligonucleotide Formats |
DNA/FANA chimeras, antisense oligonucleotides, gapmers, aptamers, hybridization probes, biosensors, and other custom XNA constructs |
| Typical Applications |
Antisense research, RNA targeting, aptamer development, XNA evolution, molecular diagnostics, biosensors, synthetic biology, and genome-engineering research |
| Key Advantages |
Enhanced RNA affinity, improved nuclease resistance, predictable Watson–Crick recognition, and flexible incorporation into chimeric oligonucleotide designs |
| Available Formats |
Fully modified FANA oligonucleotides, DNA/FANA chimeras, phosphorothioate gapmers, labeled probes, aptamers, and custom conjugates |
| Compatible Modifications |
Phosphorothioate linkages, fluorescent dyes, quenchers, affinity tags, conjugation handles, and other compatible terminal or internal modifications |
| Purification and Analysis |
Purification and analytical methods are selected according to sequence length, modification pattern, scale, and intended application |
| Storage |
Store lyophilized oligonucleotides at −20°C. Protect fluorescently labeled constructs from prolonged light exposure. Avoid repeated freeze–thaw cycles after reconstitution |
| Research Use |
For research use only (RUO), unless otherwise specified |
Product Information
2'-Fluoro-Arabino Nucleic Acid, FANA
2′-Fluoro-Arabino Nucleic Acid
Advanced Sugar-Modified XNAs
[FANA-A], [FANA-C], [FANA-G][FANA-T], [FANA-U]
-20°C To -70°C
Oligonucleotides are stable in solution at 4°C for up to 2 weeks. Properly reconstituted material stored at -20°C should be stable for at least 6 months. Dried DNA (when kept at 20°C) in a nuclease-free environment should be stable for years.
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