Adapter ligation bias happens because T4 RNA ligase works with different efficiency for different sequences. The result depends on the terminal nucleotide sequence of the RNA molecule and the adapter. Some miRNAs end up over-represented or under-represented in standard libraries. For comparative studies, this creates reproducible but false differences in abundance. Kits that use randomised adapter ends or modified ligation conditions reduce this bias and improve accuracy.
NGS - Next Generation Sequencing
RNA Library Prep Kit and Small RNA Sequencing
RNA Library Preparation Kits for Small RNA and Total RNA-Seq
Building high-quality sequencing libraries from your RNA starts with the right kit for your workflow. RNA library prep kits support total RNA-seq, and dedicated small RNA and miRNA library prep kits are optimised for the very different demands of profiling short RNA species from your plasma, serum, or cell samples.
Small RNA and miRNA library prep kits use adapter chemistry designed for short RNA species, capturing miRNA, tRNA fragments and piRNA from biofluids and tissue for your profiling work. For standard mRNA-seq, poly-A selection kits enrich the polyadenylated fraction ahead of library prep, a straightforward default for your high-quality RNA. Where sample quality is lower, such as degraded or FFPE material, rRNA depletion kits remove ribosomal RNA reads instead, providing broader transcript coverage than poly-A selection. For biofluid samples where a small number of abundant small RNAs dominate sequencing reads, selective suppression probes suppress highly abundant RNA species during small-RNA library preparation. You can select a standard panel for human plasma or request a custom panel for other organisms or tissue types.
Small RNA and miRNA library prep chemistry designed to reduce ligation bias is also available, suited to work where ligation bias would distort quantification of your rare species.
For methylation-aware RNA sequencing, RNA bisulfite-seq kits detect 5-methylcytosine in your RNA. These kits also apply to your epigenomic profiling workflows and can be found in the subcategory m6A RNA Methylation Kits for Quantification, Enzyme Activity and MeRIP.
- Small RNA vs. standard or total RNA. For small RNA sequencing (miRNA, tRNA fragments, piRNA), a small RNA library prep kit suits your workflow, with selective suppression probes available if a small number of abundant species dominate your biofluid sample. For standard mRNA-seq, a poly-A selection kit is the default choice for high-quality RNA. For total RNA-seq or degraded samples such as FFPE, an rRNA depletion kit captures your full transcriptome instead.
- Poly-A selection vs. rRNA depletion. Poly-A selection is the simpler, more cost-effective route for your intact, high-quality RNA where only the polyadenylated mRNA fraction is needed. rRNA depletion works across a wider range of sample types, including degraded, FFPE or non-polyadenylated RNA, and captures the non-coding transcripts in your sample that poly-A selection would miss.
- Ligation-bias correction. For small RNA species where ligation bias distorts quantification, kits using proprietary chemistry reduce adapter ligation bias for your results. Contact BioCat for current options.
- RNA methylation. For 5-methylcytosine detection in RNA, RNA bisulfite-seq kits suit your workflow. These sit at the intersection of RNA library prep and your epigenomics work.
Applications
Small RNA and miRNA profiling from biofluid samples
Library preparation from plasma, serum and other biofluids supports profiling of circulating miRNAs, tRFs and piRNAs for biomarker-discovery research in oncology, metabolic disease and tissue injury. Add sequence-specific blockers to suppress highly abundant RNA fragments during library preparation, freeing sequencing capacity for lower-abundance targets.
Liquid biopsy biomarker discovery
Library prep optimised for your low-input biofluid RNA, extracted with cell-free RNA purification kits, supports non-invasive disease biomarker discovery.
Epitranscriptomic profiling
RNA bisulfite sequencing sits between library preparation and RNA methylation analysis, detecting 5-methylcytosine and linking marks to your gene regulation research.
Ligation-bias-corrected miRNA quantification
Standard adapter ligation can distort miRNA abundance estimates. Chemistry that reduces ligation bias improves accuracy for your biomarker work.
rRNA depletion library preparation
rRNA depletion kits remove ribosomal RNA reads ahead of sequencing, well suited to degraded or FFPE samples where poly-A selection underperforms.
Poly-A selected mRNA-seq library preparation
Poly-A selection kits enrich the polyadenylated mRNA fraction ahead of library prep, a straightforward default for your standard gene expression studies from high-quality RNA.
Product Catalog
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Total RNA-seq
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Small RNA-seq
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RNA Depletion Kits
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Frequently asked questions
Plasma and serum samples contain a small number of highly abundant small RNA species. These dominate sequencing reads and mask low-abundance signals. Selective suppression probes hybridise to these dominant species and block their ligation to adapters during library preparation. This shifts sequencing capacity toward the wider pool of less-abundant RNAs, without the need for extra sequencing depth. Standard panels cover human plasma. Custom panels for other organisms or tissue types are available, with turnaround and pricing on request.
Plasma small RNA inputs are typically 1 to 10 ng of total RNA per library. Some protocols specify input by volume of plasma instead of by mass. Yield from biofluids is often low and variable. Carrier RNA or spike-in controls are sometimes added to check extraction and library preparation efficiency. We recommend accurate quantification of small RNA-enriched fractions before library prep.
RNA bisulfite sequencing needs a separate aliquot of RNA and dedicated library preparation. This is because bisulfite treatment is chemically harsh: it fragments RNA while converting unmethylated cytosines to uracil. You can split the same RNA stock. Use one portion for standard mRNA-seq and another for bisulfite-seq library prep, as long as you have enough input material from the extraction.
Product catalogs
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