Spatial Strand Capping for Sequence-Controlled Polynucleotide Arrays
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Solution Overview
Problem
Enzymatic polynucleotide synthesis lacks precise control over the base-by-base sequence due to template-independent polymerases adding nucleotides in an unregulated manner, leading to challenges in creating polynucleotides with specific sequences, especially in high-throughput and parallel synthesis applications.
Innovation Solution
Spatially addressable control of polynucleotide extension on an array by selectively removing 3′ blocking groups from polynucleotide strands using techniques such as electrochemistry, localized basic environments, or photocleavable groups, allowing for the synthesis of multiple polynucleotides with different sequences on the same array.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If template-independent polymerase is used for enzymatic polynucleotide synthesis, then the synthesis can be performed in aqueous environment without toxic chemicals and can create longer polynucleotides, but the base-by-base sequence control is lost and random sequences are created
Solution Approach 1:
The patent applies local quality by creating spatially distinct regions on the array where blocking groups are selectively removed. Different locations on the array have different fates: some locations have blocking groups removed allowing nucleotide addition, while others retain blocking groups preventing addition. This spatial differentiation enables precise control over which polynucleotide strands are extended at each synthesis cycle.
Solution Approach 2:
The patent segments the polynucleotide synthesis process into discrete spatial locations on an array, where each location can be independently controlled. By dividing the synthesis array into multiple addressable locations and selectively removing blocking groups at specific locations, the system achieves parallel synthesis of multiple polynucleotides with different sequences while maintaining precise base-by-base control.
2Adaptability or versatility
If multiple types of nucleotides are provided to template-independent polymerase, then sequence diversity is increased, but random sequences are created instead of controlled sequences
Solution Approach 1:
The patent applies preliminary action by pre-attaching blocking groups to the 3' ends of polynucleotide strands before synthesis begins. These blocking groups prevent nucleotide addition until selectively removed. By controlling which blocking groups are removed and when, the system ensures that only specific nucleotides are added at specific locations, achieving both sequence diversity and precision.
Solution Approach 2:
The blocking group acts as an intermediary element that mediates between the template-independent polymerase and the nucleotide addition process. The blocking group temporarily prevents nucleotide addition, and its selective removal controls when and where addition occurs. This intermediary mechanism enables precise sequence control even when multiple nucleotide types are available.
3Manufacturing precision
If blocking groups are added to control nucleotide addition, then sequence precision is improved, but the synthesis process becomes more complex
Solution Approach 1:
The patent replaces complex mechanical control systems with a simpler chemical blocking mechanism. Instead of using complex physical or enzymatic control systems to regulate nucleotide addition, the system uses chemical blocking groups that can be selectively removed by controlled chemical or physical means (such as UV irradiation or chemical treatment). This substitution simplifies the overall system while maintaining precise control.
4Productivity
If selective removal of blocking groups is performed at multiple locations, then parallel synthesis of multiple polynucleotides is enabled, but control and coordination becomes more difficult
Solution Approach 1:
The patent adds a spatial dimension to the synthesis control by using an array-based system where different locations can be independently controlled. Instead of controlling synthesis in a single dimension (time), the system uses two dimensions (space and time) by selectively removing blocking groups at different locations at different times. This enables parallel synthesis while maintaining simple control through spatial addressing.
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
Enables the efficient, parallel synthesis of polynucleotides with arbitrary sequences, improving scalability and throughput by controlling nucleotide incorporation at specific locations, overcoming the limitations of unregulated enzymatic synthesis.
Implementation Method 1
Enzymatic polynucleotide synthesis is performed with a template-independent polymerase such as terminal deoxynucleotide transferase (TdT) rather than a series of chemical reactions
Implementation Method 2
The localized basic environment may be created by electrochemistry. An electrode, such as a microelectrode integrated into the array, may cause deacylation in proximity to the electrode by generating a negative voltage that removes the acyl groups and produces free 3'-OH groups
Data Source
AI summary
Enzymatic polynucleotide synthesis with a template-independent polymerase is used to create multiple polynucleotides having different, arbitrary sequences on the surface of an array. The array provides a spatially-addressable substrate for solid-phase synthesis. Blocking groups are attached to the 3′ ends of polynucleotides on the array. Prior to polynucleotide extension, the blocking groups are removed at a selected location on the array. In an implementation, the blocking groups are acyl groups removed with a negative voltage created at an electrode. The array is then incubated with the polymerase and a single species of nucleotide. Nucleotides are incorporated onto the 3′ ends of the polynucleotides without blocking groups. Washing removes the polymerase and free nucleotides. To create polynucleotides with different sequences at different locations on the array, the location where the blocking groups are removed and the species of nucleotide may be changed during repeated cycles of synthesis.