Nucleic-acid reagents and kits
Nucleic-acid reagents cover the chain that runs from the biological sample to the result: extraction and purification of genomic DNA, plasmids, total RNA and microRNA; reverse transcription; amplification by PCR and qPCR; clean-up and size selection for NGS; agarose gel electrophoresis. In the CABRU catalogue the category holds 642 references: 337 from A&A Biotechnology, 122 from the Molecular Biology line of Condalab, 65 from Bioatlas, 57 from MAGBIO and 55 from Rovalab.
How the purification method is chosen
The method follows the sample and the downstream step, not the declared yield. A silica column binds nucleic acids at high salt concentration and releases them in a low-ionic-strength buffer: it is practical on few samples and needs no instrument. Paramagnetic beads in SPRI chemistry carry carboxyl groups and bind DNA in the presence of polyethylene glycol and salt; separation uses a magnet rather than centrifugation, which makes them suited to automation and gentler on high-molecular-weight DNA. Above all, the ratio between bead volume and sample volume governs the minimum fragment length retained: this is what makes size selection possible in NGS libraries.
| Method | Principle | Strength | To keep in mind |
|---|---|---|---|
| Silica column | Binding to silica at high salt, washing, elution | Few samples, no dedicated instrument | Needs a centrifuge; residual ethanol inhibits PCR |
| Magnetic beads (SPRI) | Carboxyl groups with PEG and salt; the bead/sample ratio sets the size cut-off | Automation, high sample numbers, size selection | Requires a magnetic rack; the ratio must be tuned |
| Liquid-phase precipitation | Precipitation with alcohol and salt | Large volumes, low cost per sample | More manual steps and more variability |
What each manufacturer covers
The A&A Biotechnology range is the broadest on sample preparation: 72 references are kits, 51 name DNA, 36 RNA and 15 plasmids, with 35 references to PCR. MAGBIO works on the magnetic side and on sequencing preparation: 11 references are classified NGS, 9 viral and pathogen DNA/RNA extraction, 6 cfDNA, 6 gDNA, 4 sequencing and 4 RNA extraction. Rovalab covers amplification — 31 references are ready mixes, 18 nucleotides, 12 Taq polymerases. Bioatlas adds PCR and electrophoresis reagents, including alternatives to ethidium bromide for gel staining. Of the Condalab molecular-biology line, 75 of the 122 references are agarose.
Before ordering
With RNA the binding constraint is RNase contamination: dedicated consumables, clean surfaces, sample stabilised straight after collection. With enzymes, storage temperature and the number of thaw cycles are what count. References can be browsed in the product catalogue, filtering by company or searching by code. If the reference sought is not there, the enquiry is passed on to the manufacturers represented.