Thiol Modifier Modification Service

Introduction

Thiol modification (thiol modification) introduces thiol groups (-SH) into oligonucleotides, enabling precise conjugation with molecules like fluorescent dyes, nanoparticles, or proteins through reactions such as thiol-gold bonding. This modification is crucial for functional expansion of oligonucleotides, supporting applications in molecular labeling, targeted delivery, and biosensor development. Creative Biolabs offers professional thiol-modified oligonucleotide services, covering custom design, high-precision synthesis, and strict quality validation, to meet diverse research and application needs.

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Thiol Modifiers

Basic

Thiol modifiers are a class of chemical reagents containing thiol groups (-SH), which provide highly reactive sites for oligonucleotides by introducing thiol groups at the 5'-end, 3'-end or internal nucleotides (such as modified dT) of oligonucleotides. Unlike the modification of thiophosphates (P-S bonds), its core function is to achieve precise functionalized conjugate rather than altering the stability of the skeleton, and it is widely used in molecular labeling, targeted delivery and the development of biosensors.

Types of thiol Modifiers

• 5'-thiol modification: Linked to the 5'-end of oligonucleotides through linkers such as C6 and C12, it has high reactivity and is suitable for conjugate fluorescent dyes or nanoparticles.
• 3'-thiol modification: Special synthetic strategies (such as 3'-thiol-CPG carriers) are required to avoid interfering with the 5'-end primer binding region, and it is suitable for PCR-related conjugate experiments.
• Internal Thiol modification: By modifying the side chain of dT, thiol groups (such as thiol-DT) are introduced, located in non-critical sequences, which do not affect hybridization activity and are suitable for multi-label design.
• Cleavable thiol modification: Derivatives containing disulfide bonds (-S-S-) that can release oligonucleotides under the action of reducing agents (such as DTT), used in controlled release scenarios.

Advantages

• Highly specific conjugate: Thiol groups can achieve directional conjugate through sulfur-gold bonds (with gold nanoparticles) and thiol-maleimide reactions (with proteins/dyes), reducing non-specific binding.
• Functionalization flexibility: Compatible with various modifications such as fluorescence labeling, biotinylation, and nanocarrier ligation, it expands the application of oligonucleotides in diagnosis and imaging.
• No interference with core functions: The modification sites avoid the key hybridization regions and do not affect the binding activity with complementary nucleic acids, ensuring the accuracy of targeted recognition.
• Controllable reactivity: The thiol group can be temporarily blocked by a protecting group (such as triphenylmethyl) and activated as needed, facilitating step-by-step experimental design.

Design

• Modification position selection: Prioritize the 5'/3' end modification to avoid interfering with hybridization. Internal modifications should avoid GC-rich regions or key sequences of secondary structures.
• linker length matching: Short-chain Linkers (such as C6) are suitable for steric hindrance sensitive scenarios (such as fluorescence resonance energy transfer experiments); Long-chain linkers (such as C12) are conducive to the conjugate of complex molecules.
• Thiol protection and activation: During synthesis, protective groups (such as S-triphenylmethyl) are needed to prevent oxidation. Before use, thiol groups are activated through deprotective agents (such as TCEP) to ensure reaction efficiency.
• Conjugate environmental control: Avoid conjugate under oxidizing conditions (such as high pH). It is recommended to react in a neutral buffer to reduce disulfide bond crosslinking by-products.

Workflow

1. Step 1: Sequence Design & Modification Strategy

   Our team analyzes target sequences, delivery routes (IV, intrathecal), and goals to optimize thiol placement (5'-end, 3'-end, or internal) via in silico modeling, avoiding disruption of hybridization or function.

2. Step 2: High-Fidelity Synthesis

   Automated solid-phase synthesis under inert conditions incorporates thiol-containing phosphoramidite monomers, with >99% coupling efficiency per step to minimize byproducts and prevent thiol oxidation.

3. Step 3: Purification & Quality Control

   HPLC/IEX removes truncated sequences and impurities;

   Mass spectrometry confirms molecular weight (±0.01% accuracy);

   Nuclease stability assays validate resistance to DNase/RNase.

4. Step 4: Timely Delivery

   Standard projects complete in 8-10 weeks (6-week expedited option), with scalable outputs (20 nmol-10 mmol). Deliverables include lyophilized oligonucleotides, HPLC/MS reports, and stability data.

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Customer Reviews

"Our collaboration with Creative Biolabs on thiol-modified oligonucleotides has been instrumental in advancing our targeted drug delivery platform. Their expertise in thiol placement, optimizing linker length and terminal vs. internal modification, ensured the oligonucleotides maintained robust target hybridization while enabling efficient conjugation with our nanoparticle carriers. This precision directly contributed to a 40% improvement in cell-specific uptake in preclinical models."

"The consistency across synthesis batches was remarkable. From 10 mg research-scale to 500 mg preclinical runs, HPLC and mass spec analyses confirmed ≥99.2% purity, with thiol reactivity (assessed via maleimide coupling assays) showing less than 2% variability. This reliability was critical as we transitioned from in vitro validation to animal studies."

"The team's ability to integrate thiol modification with phosphorothioate backbone adjustments, while adhering to stringent cGMP guidelines, streamlined our regulatory preparation. Most impactfully, their 30% faster turnaround compared to our prior partner shaved 4 weeks off our development timeline. For projects demanding precise thiol functionalization with uncompromised performance, Creative Biolabs has proven to be an indispensable collaborator."

FAQs

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