Triizol Method: A classic one-stop technique for efficiently obtaining high-quality RNA

Among numerous molecular biology experiments, RNA extraction is an essential procedure and also the first challenge for many researchers. The integrity, purity and concentration of RNA directly determine the success of downstream experiments including reverse transcription PCR, real-time quantitative PCR and RNA sequencing. The one-step extraction method based on Triizol, also known as guanidinium thiocyanate-phenol method, remains one of the most classic and widely applied techniques in laboratories to date due to its high efficiency, stability and universal applicability.

I. What is the Triizol Method?

Triizol is a monophasic strong denaturing lysis solution mainly composed of phenol and guanidinium thiocyanate. Its unique formula enables multiple functions simultaneously:

• Efficient Lysis and Denaturation: Guanidinium thiocyanate acts as a potent protein denaturant, which rapidly lyses cells and inactivates intracellular RNases (Ribonucleases), the key to protecting fragile RNA from degradation.
• Preservation of Nucleic Acid Integrity: Nucleases lose activity under denaturing conditions, ensuring RNA integrity throughout the extraction process.
• Separation of Multiple Components: A distinct advantage of this method is that the solution will form separate phases after adding chloroform, realizing the isolation of RNA, DNA and proteins.

Brief Introduction to Basic Principles:

• • Homogenization: Samples are fully homogenized in Triizol reagent to completely lyse cells, separate nucleic acids from proteins and induce denaturation.
• • Phase Separation: After adding chloroform and centrifugation, the mixture is divided into three layers:
  • Upper Aqueous Phase: Contains RNA.
  • Interphase Layer: Mainly consists of DNA and denatured proteins.
  • Lower Organic Phase: Contains proteins, lipids and other substances.
• • RNA Precipitation and Washing: Transfer the upper aqueous phase and add isopropanol to precipitate RNA. Impurities are removed via ethanol washing. Finally, dissolve the RNA pellet in RNase-free water to obtain high-purity total RNA.

II. Main Applications and Advantages of the Triizol Method

Originally designed for total RNA extraction, the Triizol method features powerful lysis and phase separation capacities, supporting a broader range of applications.

Key Advantages:

• High Yield and Good Integrity: It performs well for difficult-to-extract specimens such as lipid-rich tissues, plant tissues and trace samples, yielding intact RNA efficiently.
• Wide Compatibility: Applicable to nearly all biological samples, including animal tissues, cells, plant tissues, bacteria and yeasts.
• Multi-purpose in One Tube: While extracting RNA, DNA from the interphase and proteins from the organic phase can be collected separately for downstream assays like DNA cloning and Western blot, achieving multi-omics analysis from a single sample.
• Cost-effective: Compared with commercial column-based extraction kits, this method is more economical for high-throughput sample processing.

III. Typical Applications of the Triizol Method

Thanks to its superior performance, the Triizol method has become a fundamental technique for various life science researches.

1. Gene Expression Analysis

This is the core application of the Triizol method. High-quality RNA is the prerequisite for accurate gene expression analysis.

• Real-time Quantitative PCR: Isolated RNA is reverse transcribed for qPCR to quantitatively detect gene expression levels. RNA purity is critical, as contaminants may interfere with reverse transcription efficiency and PCR specificity.
• Northern Blot: Intact and undegraded RNA is required to accurately determine the size and abundance of target RNA molecules.
• RNA Sequencing: As a mainstream transcriptome research technology, RNA-Seq demands highly intact RNA. RNA extracted by Triizol with high integrity value guarantees reliable sequencing data.

2. RNA Extraction from Challenging Samples

• RNase-rich Tissues: For tissues with high RNase activity such as pancreas and spleen, strong denaturants in Triizol instantly inactivate RNases.
• Plant Tissues: Plant cells possess rigid cell walls and abundant secondary metabolites like polysaccharides and polyphenols. Triizol effectively disrupts cells, dissolves interfering substances and separates them from RNA via phase separation.
• Adipose Tissues: Column-based methods often fail due to lipid clogging, while the Triizol method works stably for lipid-rich samples.

3. Integrated Multi-omics Analysis

Modern systems biology often requires multi-layer information including transcriptomics and proteomics from the identical sample.

• Simultaneous Extraction of RNA and Protein: After total RNA isolation, total protein can be further precipitated and recovered from the lower organic phase for Western blot, mass spectrometry and other assays. It ensures consistent sample sources for different omics analyses and reduces experimental errors.

4. Viral RNA Detection

In virological research and clinical diagnosis, such as detection of influenza virus and coronavirus, viral RNA needs to be directly extracted from throat swabs, tissue culture fluid and other specimens. Triizol efficiently disrupts viral capsids, releases and protects viral RNA, providing qualified templates for subsequent RT-PCR detection.

Key Notes for Experiments

Although the Triizol method is robust, the following points must be observed to obtain ideal results:

• RNase-free Operation: Perform experiments in a dedicated area with RNase-free consumables and solutions to avoid exogenous RNase contamination.
• Rapid Manipulation: Complete downstream steps immediately after sample lysis to minimize RNA exposure to potential degradation risks.
• Phase Separation and Transfer: Pipette the upper aqueous phase carefully without touching the interphase to prevent DNA and protein contamination.
• Adequate Washing and Drying: Fully remove residual ethanol after ethanol washing. Do not over-dry the RNA pellet, otherwise it will be difficult to dissolve.

Summary

As a time-tested fundamental molecular biology technique, the Triizol method features strong lysis capability, excellent RNA protection effect and the unique advantage of three-component extraction in one tube. It plays an irreplaceable role in gene expression analysis, multi-omics research and processing of various complex samples. Mastering its principles and operational details is an essential skill for researchers engaged in RNA-related studies. Despite the emergence of convenient column-based kits, the Triizol method still maintains an unshakable position for applications requiring high yield, superior RNA integrity and simultaneous isolation of multiple components.

Absin Triizol Recommendations:

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