Automation workflow for high-throughput arrayed plasmid DNA preparation and quantification.

Abstract

High-throughput generation of arrayed plasmid DNA library using commercially available miniprep kits remains labor-intensive and costly. The yield and quality of plasmid preparations directly affect downstream applications, including arrayed viral library production and CRISPR library screening. Insufficient plasmid yield or DNA concentration often requires repeated preparations or additional DNA concentration steps to obtain adequate quantities. Similarly, higher variations in yield or quality across wells or plates can render an entire library unsuitable for subsequent experiments. To increase productivity and mitigate human intervention and errors, the present study established an automated workflow for high-throughput plasmid DNA preparation and quantification. The workflow was carried out by the Biomek i7 Hybrid automated workstation, synergizing a robotic liquid handler and multiple peripheral instruments to produce and measure plasmid DNA in a 96-well plate format. Bacterial competent cells were alkaline lysed and plasmid DNA was purified using magnetic beads, followed by quantification with the PicoGreen assay. The PicoGreen assay reported median and average yields of approximately 9.5 and 10 {micro}g per sample, respectively, which are equivalent to 7.6 and 8 {micro}g/mL of bacterial culture. Plasmid DNA concentrations measured by the PicoFluor fluorometer were consistently lower than those obtained using the NanoDrop UV spectrophotometer. The comparison demonstrated robust positive correlation between PicoGreen assay and NanoDrop measurements (R2 > 0.8). Among 480 plasmid DNA samples, average and median yields measured by the NanoDrop reached approximately 24 and 25 {micro}g per sample per well, corresponding to 19 and 20 {micro}g/mL of bacterial culture. Over 98% of samples exceeded the high-yield threshold of 10 {micro}g/mL of culture, with high plasmid quality validated through DNA gel electrophoresis. Collectively, this study demonstrated a robust, scalable, and cost-effective automation platform for high throughput arrayed plasmid library generation and quantification.