Subnanogram Detection of Silver Stained Protein Bands with Thermal Lens Spectrometry

Abstract Sodium dodecyl sulfate polyacrylamide gel electrophoresis is a standard biochemical technique to separate, detect and quantify protein amounts of specific molecular weights. Colorimetric detection with Coomassie or silver stain is by far the most common analysis method. Silver stain is the most sensitive one and protein bands down to 1 ng can be detected with laboratory imaging systems. To increase the sensitivity of the detection we developed a sensor based on the principle of the thermal lens effect to scan, record, and quantify protein bands not visible to the eye or to the camera. Our device could detect bands of 0.05 ng in gels soaked in methanol/water and 0.1 ng when soaked in water.