How to Detect Disease Markers Using Colored Proteins

A 1981 method for measuring disease-related proteins in blood by attaching them to naturally colored proteins that can be detected with light.

What it covers

This patent describes a way to find specific substances (antigens) in blood or cells by using a special 'tag.' The process involves creating a reagent by chemically bonding an antibody—which naturally seeks out a specific target—to a 'chromoprotein' like ferritin or cytochrome c. Because these chromoproteins have a natural color, they absorb specific wavelengths of light. When the tagged antibody binds to the target in a sample, the resulting mixture can be measured using a standard light-measuring device (colorimeter) to determine exactly how much of the target substance is present.

What it doesn't cover

• —Does not cover methods using radioactive labels for detection
• —Does not cover fluorescent markers or labels that require excitation light
• —Does not cover detection methods that rely on enzymatic color changes rather than the inherent color of the protein
• —Does not cover the use of synthetic dyes or artificial chromophores

The clever bit

Instead of using an artificial dye, the inventor used naturally occurring proteins (like ferritin) that already possess a distinct color, effectively turning a biological molecule into a built-in sensor.

Why it matters

Before this method, detecting specific proteins often required complex, expensive, or radioactive techniques. By using naturally colored proteins that were already abundant in biological research, this patent provided a path toward simpler, direct colorimetric assays that could be performed with standard lab equipment.

Real-world examples

• 1.Diagnostic blood serum testing
• 2.Protein concentration analysis in clinical labs
• 3.Bacterial antibody detection