Introduction to Chemiluminescent Western Blotting

Chemiluminescent Western blotting is the gold standard for protein detection in molecular biology research. This comprehensive guide covers everything you need to know about chemiluminescent detection systems, including substrate selection, optimization, and troubleshooting.

What is Chemiluminescence?

Chemiluminescence is a light-emitting chemical reaction used to detect proteins on Western blot membranes. The process involves enzyme-conjugated antibodies (typically HRP or alkaline phosphatase) that catalyze the oxidation of luminol-based substrates, producing light that can be captured on film or digital imagers.

Types of Chemiluminescent Substrates

HRP Substrates

Horseradish peroxidase (HRP) substrates are the most common detection reagents for Western blotting:

• Entry-Level: PicoGlow substrates offer basic sensitivity at economical prices
• High-Sensitivity: FemtoGlow substrates detect femtogram quantities of protein
• Extended Signal: Substrates with stabilizers maintain signal for hours

Alkaline Phosphatase (AP) Substrates

AP substrates like AttoGlow offer advantages for certain applications:

• Attogram-level sensitivity with enhancer reagents
• No interference from endogenous peroxidases
• Longer signal stability (2+ hour plateaus)
• Compatible with stripping and reprobing

Optimizing Western Blot Detection

Choosing the Right Substrate

Substrate selection depends on target protein abundance:

• High abundance proteins: Entry-level substrates (PicoGlow)
• Medium abundance: Standard FemtoGlow substrates
• Low abundance: Enhanced sensitivity substrates (FemtoGlow Plus, AttoGlow with enhancer)

Common Issues and Solutions

High Background: Use low-background formulations, optimize blocking buffer, reduce antibody concentrations

Weak Signal: Increase antibody concentration, extend incubation times, use higher sensitivity substrate

Uneven Signal: Ensure even transfer, adequate membrane wetting, proper washing

Best Practices

• Always use fresh substrate (stable 45 days after opening for most formulations)
• Store proteins at -20°C to maintain activity
• Use appropriate membrane type (PVDF for proteins >20 kDa, nitrocellulose for <20 kDa)
• Document exposures at multiple time points
• Include positive and negative controls

Shop Chemiluminescent Substrates

Michigan Diagnostics offers a complete line of chemiluminescent substrates for Western blotting, including our flagship FemtoGlow HRP substrates and AttoGlow AP substrates. All products are manufactured in the USA with FDA-compliant quality systems.

Comparing FemtoGlow and AttoGlow Substrates

Choosing between FemtoGlow HRP substrates and AttoGlow AP substrates depends on your specific Western blotting needs. This comparison guide helps you select the optimal detection system for your research.

FemtoGlow HRP Substrates

Best For:

• Standard Western blotting protocols
• High-throughput screening
• Budget-conscious laboratories
• ELISA and chemiluminescent immunoassays

Advantages:

• Fast signal development (1-5 minutes)
• Compatible with all standard HRP-conjugated antibodies
• Economical for routine applications
• Available in single-bottle or two-bottle formats

Sensitivity Range:

Femtogram to picogram detection depending on formulation

AttoGlow AP Substrates

Best For:

• Ultra-low abundance proteins (attogram detection)
• Multiplexing experiments
• Membrane stripping and reprobing
• Applications requiring extended signal stability

Advantages:

• Attogram-level sensitivity with enhancer
• Extended signal plateau (2+ hours)
• No endogenous peroxidase interference
• Available in 450nm and 540nm emission variants

Sensitivity Range:

Attogram to femtogram detection with enhancer reagents

Side-by-Side Comparison

Feature	FemtoGlow (HRP)	AttoGlow (AP)
Sensitivity	Femtogram	Attogram
Signal Duration	30 min – 2 hours	2+ hours
Development Time	1-5 minutes	25-45 minutes
Price Point	Economy	Premium

Making Your Choice

Choose FemtoGlow if: You need fast, reliable detection for medium-to-high abundance proteins with standard HRP workflows

Choose AttoGlow if: You require maximum sensitivity for rare proteins or plan to strip and reprobe membranes

Order Samples

Not sure which substrate is right for you? Contact us to request trial sizes of both FemtoGlow and AttoGlow substrates.