Nucleic Acid Fragment Assembly via Phosphoramidite Coupling
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Solution Overview
Problem
Conventional phosphoramidite chemistry for nucleic acid synthesis is limited by low stepwise coupling efficiency, resulting in short oligonucleotide lengths, and current methods for producing longer sequences are labor-intensive and time-consuming.
Innovation Solution
A method involving the synthesis of longer nucleic acid fragments in parallel and binding them together using phosphoramidite coupling, with fragments having ends rendered unreactive or less reactive to prevent erroneous growth, allowing for increased yield and length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If conventional phosphoramidite chemistry is used for nucleic acid synthesis, then the synthesis process is simple and well-established, but the oligonucleotide length is limited to roughly 100-mers for DNA and 60-mers for RNA due to finite and compounding stepwise coupling yield
Solution Approach 1:
The patent divides the synthesis process into two distinct phases: (1) parallel synthesis of multiple shorter oligonucleotide fragments with high coupling efficiency, and (2) assembly of these pre-synthesized fragments into longer sequences. This segmentation allows each fragment to be synthesized with reliable coupling yield while the final product achieves much greater length than conventional single-phase synthesis permits.
Solution Approach 2:
The patent performs preliminary synthesis of oligonucleotide fragments to a defined length before assembly. By pre-synthesizing fragments with controlled lengths and purifying them separately, the method ensures high coupling efficiency in each fragment while enabling subsequent assembly into longer sequences that would be impossible to synthesize directly in one continuous process.
2Length of moving object
If all strands bear a 5'-OH thermally cleavable protecting group with selective thermal deprotection, then longer oligonucleotides can be synthesized, but the approach has inherent limitations and shortcomings
Solution Approach 1:
Instead of using a single protecting group strategy applied uniformly to all strands, the patent segments the synthesis into separate fragment synthesis and assembly phases. Each fragment is synthesized independently with standard protecting groups, then assembled through controlled phosphoramidite coupling. This avoids the complexity of selective thermal deprotection while achieving longer sequences.
Solution Approach 2:
The patent introduces an intermediary assembly phase where pre-synthesized fragments are joined through controlled phosphoramidite coupling reactions. This intermediary step acts as a mediator between fragment synthesis and final product formation, allowing length extension without requiring complex protecting group chemistry or thermal deprotection mechanisms.
3Productivity
If conventional stepwise monomer addition is used, then the synthesis process is straightforward, but the synthesis time can easily take up several weeks for longer oligonucleotides
Solution Approach 1:
The patent segments the overall synthesis into parallel fragment synthesis and sequential assembly phases. Multiple fragments can be synthesized simultaneously in parallel, then assembled in a controlled manner. This segmentation dramatically reduces total synthesis time compared to sequential monomer addition while achieving much longer final sequences.
Solution Approach 2:
By performing preliminary synthesis of multiple fragments in parallel before assembly, the patent eliminates the sequential bottleneck of conventional synthesis. The time-consuming assembly step is performed only after all fragments are ready, allowing significant time savings while producing longer oligonucleotides than conventional methods permit.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly increases the practical length and yield of nucleic acids synthesized, reducing synthesis time and eliminating the need for dedicated purification steps.
Implementation Method 1
In the coupling step, a covalent bond is formed between the incoming phosphoramidite and the immobilized nucleic acid strand
Implementation Method 2
a new building block is added to the surface-tethered growing strand in a monomer addition cycle which exists of four essential steps: coupling, capping, oxidation and detritylation
Data Source
AI summary
In a first aspect, the present disclosure relates to a method for synthesizing a nucleic acid or nucleic acid analogue, comprising: a) providing a root fragment of the nucleic acid or nucleic acid analogue, b) providing a further fragment of the nucleic acid or nucleic acid analogue, c) phosphitylating either the root fragment or the further fragment, and d) binding the further fragment to the root fragment by a phosphoramidite coupling; wherein the root fragment and the further fragment each have a length of at least 5 monomers.