rA(bz)-lcaa-CPG co-polymer

What is rA(Bz)?

rA(Bz) is a commonly used abbreviation in nucleic acid chemical synthesis.
Its full name is N6-Benzoyl-adenosine.

• r (ribo): Indicates ribose, meaning this is an RNA component rather than DNA (which is typically denoted as dA).
• A (Adenosine): Refers to adenosine, with adenine as the nucleobase.
• Bz (benzoyl): Refers to the benzoyl protecting group attached to the N6 position of adenine.

About the (Bz) Protecting Group

During oligonucleotide synthesis, the amino group (–NH₂) on the adenine base is chemically reactive and can participate in unwanted side reactions, potentially leading to synthesis failure.

To prevent this, the N6 position of adenine is protected with a benzoyl (Bz) group during synthesis.

After completion of the full RNA chain assembly, standard deprotection using aqueous ammonia (NH₃·H₂O) removes the Bz group, restoring the native adenosine structure.

Applications of rA(Bz)-CPG

siRNA

rA(Bz)-CPG is commonly used in siRNA synthesis. Whenever the 3′-terminal starting base of either the sense or antisense strand is adenine (A), rA(Bz)-CPG is typically selected as the solid support.

ASO

In DNA–RNA chimeric oligonucleotides or gapmer designs, RNA residues are often placed at the terminal regions.
rA(Bz)-CPG is used for initiating synthesis at the 3′ end of the RNA segment, or in fully RNA-based ASO projects.

CRISPR gRNA / sgRNA

rA(Bz)-CPG is used as the starting support when the 3′ end of a gRNA or sgRNA begins with adenine, or for chemically synthesized RNA fragments prior to in vitro transcription.

mRNA

rA(Bz) is a classical and highly compatible adenosine protecting strategy, well suited for downstream 2′-modifications and phosphorothioate chemistry.

The 3′ end of mRNA typically contains a long poly(A) tail. rA(Bz)-CPG serves as the first nucleoside for the chemical synthesis of this poly(A) sequence.

In addition, rA(Bz)-CPG can be used in mRNA capping-related synthesis. Overall, rA(Bz)-CPG ensures that the chemically synthesized RNA chain possesses a well-defined riboadenosine at the 3′ end.

Benefits of Co-Polymer Coated rA(Bz)-CPG in GMP-Scale Industrial RNA Oligonucleotide Production

Ultra-high loading capacity

PoresynSolutions‘ co-polymer coated CPG solid support delivers 3–6× higher loading than conventional functionalized CPG solid supports, significantly increasing RNA oligonucleotide output per batch.
For example, our 2000 Å HL-CPG achieves 160–180 μmol/g, clearly outperforming traditional functionalized CPGs used in RNA synthesis.

High crude RNA purity

Achieves >80% crude purity due to the co-polymer coating’s excellent resistance to acidic, basic, and organic solvents commonly used in RNA synthesis and deprotection, thereby reducing downstream purification burden.

Stable physical structure

Maintains a rigid, non-swelling structure throughout coupling, oxidation/sulfurization, and thermal treatments, unlike polystyrene-based resins that may swell or deform under GMP-scale processing conditions.

No silica contamination

The co-polymer coated CPG does not shed silica particles during cleavage and deprotection, preventing column clogging, minimizing backpressure, and ensuring reliable synthesis of long and complex RNA oligonucleotides, including siRNA and gRNA.