Separation and isolation of subcellular-sized particles by electrophoresis in polymer solution using the commercial scanning apparatus

Electrophoresis of fluorescently labeled rat liver microsomes and polystyrene carboxylates of 10 and 30 nm radius was conducted in buffered 10-15% polyvinylpyrrolidone (M_r = 10⁶) solutions, using a horizontal gel electrophoresis apparatus with intermittent scanning of fluorescence (HPGE-1000, LabIntelligence). Banding, constant migration rates and Ferguson plots were obtained in these polymer solutions. The major microsome band detected by the automated scan was located visually on the gel by means of its fluorescein label and was isolated by volumetric withdrawal; recovery was monitored by scanning and ascertained to be near quantitative after three consecutive steps, in each of which 30 μL were withdrawn. This preparative method promises to be generally applicable to particles that are too large to enter into gels.