A laser densitometer for selective spot analysis on dot blots and two-dimensional gel autoradiograms

Area of Science:

• Biotechnology
• Analytical Chemistry
• Instrumentation

Background:

• Accurate quantification of radioactive isotopes on gels and chromatograms is crucial for biological and chemical analysis.
• Commercial densitometers can be expensive and may lack flexibility for diverse sample types.

Purpose of the Study:

• To describe the development and performance of an inexpensive, open-table laser densitometer.
• To demonstrate its capability for accurate measurement of radioactive isotopes on two-dimensional gel autoradiograms and chromatograms.

Main Methods:

• Utilized a HeNe laser and an IBM-compatible personal computer for data acquisition and analysis.
• Employed a commercially available software package (ASYST) for data processing, including background subtraction and peak integration.
• Designed an open-table instrument with minimal moving parts for flexibility and visual monitoring.

Main Results:

• The densitometer achieves accuracy and sensitivity comparable or superior to commercial instruments.
• It measures optical density (OD) in the range of 0.25 to 3.0 OD units.
• Capable of quantifying a 10,000-fold range of 14C or 35S isotope concentrations on autoradiograms.
• Analysis time is rapid, taking 20-30 seconds per spot.

Conclusions:

• An inexpensive, user-friendly laser densitometer can be assembled for less than $3000.
• This instrument provides a cost-effective alternative for accurate radioactive quantification in research settings.
• The open design enhances flexibility for scanning various sample types and sizes.