Home Genetics / Genomics NEBNext Ultra II DNA Library Prep Protocol
Steps
  1. 1 Prepare DNA sample and reagents 00:02
  2. 2 Perform end repair and dA-tailing 01:16
  3. 3 Ligate adaptors to DNA fragments 02:18
  4. 4 Perform size selection with magnetic beads 03:57
  5. 5 Amplify library by PCR 07:17
  6. 6 Purify PCR product using magnetic beads 08:05
  7. 7 Verify and quantitate final library 09:29
Genetics / Genomics New England Biolabs

NEBNext Ultra II DNA Library Prep Protocol

Protocol
Difficulty
intermediate

Steps

1
Prepare DNA sample and reagents

Fragment DNA to the appropriate size range and adjust the sample volume to 50 µl containing 500 pg to 1 µg of fragmented DNA. Ensure all kit reagents are well mixed before use.

▶ 00:02
2
Perform end repair and dA-tailing

Add 3 µl of End Prep Enzyme Mix and 7 µl of End Prep Reaction Buffer to the 50 µl fragmented DNA sample. Incubate at 20°C for 20 minutes, then 65°C for 20 minutes, and hold at 4°C.

▶ 01:16
3
Ligate adaptors to DNA fragments

Add Ultra II Ligation Master Mix, Ligation Enhancer, and Adaptor to the End Prep reaction and mix thoroughly. Incubate at 20°C for 15 minutes with heated lid off, then add USER enzyme and incubate at 37°C for 15 minutes.

▶ 02:18
4
Perform size selection with magnetic beads

Conduct two rounds of magnetic bead-based size selection: the first round removes large DNA fragments and the second removes small DNA fragments. Wash the beads with 80% ethanol, allow to air dry, and elute the library in 17 µl of Tris-HCl or 0.1X TE Buffer.

▶ 03:57
5
Amplify library by PCR

Add universal PCR primer, index primer, and Ultra II Q5 Master Mix to the 15 µl eluted library sample. Run PCR with the appropriate number of cycles based on the original input DNA amount.

▶ 07:17
6
Purify PCR product using magnetic beads

Add 45 µl of vortexed magnetic beads to the PCR reaction and incubate for 5 minutes. Remove supernatant, wash beads with 80% ethanol, allow to air dry, and elute the final library in 33 µl of 0.1X TE Buffer.

▶ 08:05
7
Verify and quantitate final library

Confirm the size distribution of the library by running a diluted sample on a Bioanalyzer using the High-Sensitivity Chip. Quantitate the library using qPCR-based methods or electrophoretic methods.

▶ 09:29

🚨 Failure Case Library (7) + Submit your own case

critical
Complete Library Preparation Failure
No library visible on Bioanalyzer or similar instrument after amplification, or library fragments remain the same size as input DNA instead of showing expected ~120 bp increase in size.
💡 4 · ✓ 4
severe
Low Library Yield with Intact Input DNA
Library yield is significantly lower than expected based on input amount, despite successful completion of all enzymatic steps.
💡 4 · ✓ 4
severe
Sample Loss During SPRI Bead Cleanup
Significantly lower library yield after SPRI bead cleanup steps, with visible reduction in final library concentration disproportionate to expected recovery rate.
💡 5 · ✓ 5
severe
Library Overamplification with Heteroduplex Formation
High molecular weight fragments appear on Bioanalyzer after PCR due to single-stranded library fragments and heteroduplex formation when PCR primers are depleted. Data quality may be compromised upon sequencing.
💡 4 · ✓ 4
moderate
Residual Adaptor or Primers After PCR
Adaptor or primer peaks visible on Bioanalyzer or similar instrument after PCR amplification, indicating inefficient cleanup or excess reagent usage.
💡 3 · ✓ 3
moderate
Excessive Adaptor Dimer Formation
Sharp 127 bp peak visible on Bioanalyzer representing adaptor dimers, reducing the proportion of desired library fragments and overall usable yield.
💡 3 · ✓ 4
moderate
Library Not the Correct Insert Size
Library fragment size distribution is shifted from expected range, with either smaller or larger inserts than intended, or discrepancy between fragment analyzer measurement and sequencer-determined insert size.
💡 5 · ✓ 5
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