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Circular Single-Stranded DNA

Circular single-stranded DNA (cssDNA), also known as single-stranded plasmid DNA, is a DNA molecule characterized by its closed-loop structure. Unlike conventional linear DNA, cssDNA features covalently linked 5′ and 3′ ends, forming a continuous, stable circular structure.

At BiOligo, we leverage years of expertise in oligonucleotide synthesis. We have established a proprietary High-Precision Solid-Phase Synthesis Platform and an Optimized Circularization Technology that together enable the efficient synthesis of high-quality cssDNA.

Features

Patented Circularization Technology

  • We employ a two-step end-modification and ligation strategy to achieve > 95% cyclization efficiency, drastically minimizing linear DNA impurities.

Precise Sequence Control

  • Our proprietary sequence design system optimizes synthesis for challenging sequences (including GC-rich and repetitive regions), ensuring sequence accuracy above 99.9%.

Fully Customizable Options

  • We support over 200 modifications and offer secondary structure prediction analysis, allowing us to meet your diverse and personalized research needs.

Rigorous Quality Control (QC)

  • Utilizing proprietary purification processes, we guarantee a purity of 95%. Mass Spectrometry and HPLC thoroughly validate each batch, and a complete QC report is provided.

Fast Turnaround

  • Our streamlined production and quality assurance processes ensure the rapid delivery of your customized cssDNA products.

Base LengthLead Time
15-50 nt≤ 7 BD
50-105 nt≤ 10 BD
106 ntInquire

Cases

Example: Synthesis of 20 nt, 30 nt, and 50 nt Circular Single-Stranded DNA
In this example, single-stranded DNA fragments of 20 nt, 30 nt, and 50 nt were synthesized and circularized by covalently joining the 5′ phosphate and 3′ hydroxyl termini to form a stable circular structure.
(1) Mass Spectrometry (MS): Confirms the expected molecular weight of the circularized DNA.
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20 nt single-stranded linear DNA
20 nt circular single-stranded DNA
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30 nt single-stranded linear DNA
30 nt circular single-stranded DNA
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50 nt single-stranded linear DNA
50 nt circular single-stranded DNA

The target molecular weight shows a decrease of approximately 18 Da after circularization, consistent with the characteristic change observed when linear ssDNA forms a circular structure. During the cyclization process, one molecule of H2O is released, resulting in an 18 Da reduction in molecular weight.

 

(2) High-Performance Liquid Chromatography (HPLC): Demonstrates high product purity and minimal linear DNA residues.
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20 nt circular single-stranded DNA, purity: 98.95%
30 nt circular single-stranded DNA, purity: 98.99%
50 nt circular single-stranded DNA, purity: 99.00%

 

BiOligo offers customized synthesis of short circular single-stranded DNA, delivering structural stability, precision synthesis, and tailored design. We support research institutions, diagnostic developers, and pharmaceutical companies with reliable, high-performance nucleic acid tools.