Gel Stains

Loading Dye

<h2>What is gel loading dye?</h2>
&nbsp;
Gel loading dye, also called sample loading buffer or tracking dye, is a concentrated solution mixed with a DNA, RNA, or protein sample immediately before it is loaded into a gel well. It serves two essential functions: the density agent, typically glycerol at 30&ndash;60% or Ficoll, makes the sample denser than the running buffer so it sinks to the well bottom rather than diffusing back out; and the tracking dyes, most commonly bromophenol blue and xylene cyanol FF, provide visible colored bands that co-migrate at defined, approximate DNA equivalent sizes to allow the researcher to monitor migration progress and estimate when to stop the run.
&nbsp;
<h2 dir="ltr">What you will find:</h2>
&nbsp;
<ul>
<li dir="ltr" style="font-family: arial, helvetica, sans-serif;" aria-level="1">
Azura SmartStain Loading Dye for the same preparation and loading
</li>
<li dir="ltr" style="font-family: arial, helvetica, sans-serif;" aria-level="1">
Safe-Red loading dye for visualization of nucleic acids in electrophoresis workflows
</li>
<li dir="ltr" style="font-family: arial, helvetica, sans-serif;" aria-level="1">
Safe-Green loading dye for gel analysis and DNA tracking applications
</li>
<li dir="ltr" style="font-family: arial, helvetica, sans-serif;" aria-level="1">
SmartGlow&trade; Loading Dye with Safe Green Stain for visualization and integrated sample loading
</li>
</ul>
&nbsp;
<h2>How to choose and use gel loading dye</h2>
&nbsp;
Use 6X loading dye at 1/6 volume of total sample volume
Most gel loading dyes are formulated as 6X concentrates so that adding one part loading dye to five parts sample brings the total volume to the final working concentration. For a 10 &micro;l final load, add 2 &micro;l of 6X loading dye to 8 &micro;l of DNA or RNA sample and mix well before loading.
Choose tracking dye colors that won't obscure your expected DNA band sizes
Bromophenol blue co-migrates with approximately 300&ndash;370 bp in a 1% TAE agarose gel, while xylene cyanol co-migrates with approximately 3,000&ndash;4,000 bp in the same conditions. If your samples are expected near those sizes, using a loading dye that includes orange G instead, which co-migrates below 50 bp, avoids masking bands with the tracking dye front.
Confirm EDTA is included if nuclease protection matters for your samples
A standard 6X loading dye contains 60 mM EDTA, which chelates divalent metal ions that nucleases require for activity, providing protection against DNA degradation during sample preparation and the gel run. If your protocol requires EDTA-free loading buffer, confirm the dye formulation before use.
For RNA samples, ensure your loading dye is RNase-free
RNase contamination in loading dye can degrade RNA samples during preparation before loading, so RNA gel experiments require either RNase-free certified loading dye or dye preparation from RNase-free reagents. Using the same nuclease-free water and handling precautions for loading dye as for the RNA samples themselves is standard practice.
Be aware that SDS-containing loading buffers for protein SDS-PAGE differ from nucleic acid loading dyes
SDS-PAGE protein loading buffers contain SDS, dithiothreitol or beta-mercaptoethanol as a reducing agent, and glycerol, which are specifically required for protein denaturation and separation under SDS conditions, whereas nucleic acid loading dyes contain no SDS or reducing agents. The two formulations are not interchangeable.
&nbsp;
<h2>Specifications context</h2>
&nbsp;
A standard 6X DNA loading dye formulation typically contains 10 mM Tris-HCl (pH 7.6), 0.03% bromophenol blue, 0.03% xylene cyanol FF, 60% glycerol, and 60 mM EDTA, making it compatible with both TAE and TBE running buffers. As of 2026, ready-to-use loading dyes pre-mixed as part of ready-to-load DNA ladder products remain popular for eliminating the need for a separate mixing step before gel load
<a href="https://mbpinc.net/contact-us">Contact the expert team at MBP</a> to obtain high-quality DNA loading dyes for your research workflows.

Azura SmartStain Loading Dye 1ml

AZ4500-LDZ by Azura Genomics is a 1 mL, 6× agarose gel loading dye with integrated SmartStain™ that detects as little as 0.1 ng DNA, excites at both 290 nm and 490 nm for UV and blue-light imaging, and eliminates the need for separate EtBr gel staining.

Manufacturer

Pre-Stain/Casting

<h2>What is pre-stain/casting in gel electrophoresis?</h2>
&nbsp;
Pre-staining is the practice of incorporating a fluorescent DNA-intercalating dye into molten agarose before it is poured into the gel tray and allowed to solidify, so that when DNA migrates through the gel under the electric field, bands become fluorescent as the DNA molecules bind dye molecules pre-distributed throughout the matrix. This approach allows bands to be monitored by UV or blue-light visualization during the run and eliminates the separate post-run soaking step that post-staining requires.
&nbsp;
<h2 dir="ltr">What you will find:</h2>
&nbsp;
<ul>
<li dir="ltr" style="font-family: arial, helvetica, sans-serif;" aria-level="1">
Azura SmartStain Pre-Stain for visualization of DNA during gel casting
</li>
<li dir="ltr" style="font-family: arial, helvetica, sans-serif;" aria-level="1">
SmartGlow&trade; Safe Green Pre-Stain for DNA/RNA detection in gels
</li>
<li dir="ltr" style="font-family: arial, helvetica, sans-serif;" aria-level="1">
BlinkBlue&reg; SDS-PAGE Staining Buffer for gel analysis of proteins
</li>
<li dir="ltr" style="font-family: arial, helvetica, sans-serif;" aria-level="1">
SafeView Classic gel stain for day-to-day nucleic acids visualization during electrophoresis
</li>
</ul>
&nbsp;
<h2>How to choose and use pre-cast gel stains</h2>
&nbsp;
Add ethidium bromide at the standard concentration when safety constraints allow
Ethidium bromide, the classic pre-cast stain, is typically added to cooled, molten agarose at approximately 0.5 &micro;g/ml before pouring, providing excellent sensitivity with standard UV transilluminator imaging. Its mutagenicity requires standard handling precautions and specific waste disposal practices.
Substitute GelRed or SYBR Safe for a safer pre-cast stain option
GelRed and SYBR Safe can both be incorporated into molten agarose before casting as direct ethidium bromide substitutes at the manufacturer's recommended working concentrations, using standard UV (GelRed) or UV/blue light (SYBR Safe) for visualization on the same equipment.
Be aware that GelRed precast gels can affect DNA migration in some samples
GelRed's larger molecular size means it can cause abnormal band migration in precast gels for some samples, notably restriction digest products, compared with ethidium bromide precast gels, and this is why GelRed is specifically recommended for post-staining rather than pre-casting when migration accuracy matters most.
Cool agarose to approximately 55&ndash;60&deg;C before adding heat-sensitive staining reagents
Some intercalating dyes degrade or lose activity at the temperatures used to keep agarose liquid for pouring, and adding stain only after the agarose has cooled to approximately 55&ndash;60&deg;C, just before pouring, ensures consistent staining without heat-induced dye degradation.
Use blue-light gel imaging for downstream DNA recovery from pre-stained gels
If DNA will be excised from a pre-stained gel for downstream use, UV light should be minimized during excision because UV irradiation can introduce pyrimidine dimers and other photodamage that reduces downstream enzymatic efficiency. GelRed and SYBR Safe pre-cast gels can be imaged with a blue or amber light system to avoid this damage.
&nbsp;
<h2>Specifications context</h2>
&nbsp;
When ethidium bromide is used as a pre-cast stain, the positively charged EtBr molecules migrate toward the negative electrode during electrophoresis, moving out of the gel over time into the running buffer, which means the gel is effectively self-destaining during the run and background is reduced without a separate destaining step. As of 2026, EtBr-free labs most commonly use GelRed in post-staining applications for its superior sensitivity, while SYBR Safe is widely used as a pre-cast stain in labs that prioritize downstream DNA compatibility and blue-light gel excision.
<a href="https://mbpinc.net/contact-us">Contact the expert team at MBP</a> to get the right pre-staining/casting solutions for your lab.

Azura SmartStain Pre-Stain 1ml

AZ4500-PSZ by Azura Genomics: 1 ml EtBr-alternative nucleic acid pre-stain for agarose gels. Excitation at 290 nm (UV) and 490 nm (blue light). Detects 0.1 ng DNA. Green fluorescence for DNA, red for RNA. No post-run destaining required.