How to Clean and Sterilize Beads

Most glass, zirconia, and steel beads can be reused after proper washing, rinsing, drying, and sterilization.

BioSpec does not certify beads as nuclease-free, but most customers use them directly from the bottle. If your workflow requires reused beads, follow the cleaning and sterilization steps below.

Cleaning Glass or Ceramic Beads

1. Promptly rinse used beads with tap water.
2. Soak the beads in a diluted laboratory detergent or automatic dishwasher detergent solution.
3. Periodically agitate the beads by swirling the container.
4. Once sufficient beads have accumulated, thoroughly rinse away detergent residue using several changes of tap water followed by RO or distilled water.
5. Dry the beads overnight in an open stainless steel or glass tray at 40–70°C.

If the dried beads do not pour freely and remain caked together, insufficient cleaning or rinsing has occurred. In this case, repeat the cleaning procedure.

Cleaning Stainless Steel Beads

Stainless steel beads require a modified cleaning protocol:

1. Limit the detergent washing step to only a few minutes.
2. Rinse briefly with water.
3. Immediately remove residual moisture by rinsing the beads with three changes of absolute ethanol, isopropanol, or acetone.
4. Air dry at room temperature.

Decontamination for Nucleic Acid Applications

When isolating nucleic acids from disrupted cells, an effective alternative cleaning method is to immerse the beads in a 1:10 dilution of household bleach for 5 minutes.  This procedure cleans and sterilizes the beads while also destroying contaminating nucleic acids and nucleases (see http://www.ncbi.nlm.nih.gov/pubmed/1571142).

After bleach treatment, thoroughly rinse the beads with sterile, RO, or distilled water before reuse.

Chrome Steel Beads

Chrome steel beads are intended for single use and should generally be discarded after use.  However, they may be autoclaved if necessary.

Autoclaving Recommendations

All cleaned beads may be autoclaved.  Please note that standard autoclave conditions (121°C for 20 minutes) may not completely eliminate contaminating nucleic acids.  For more effective destruction of residual DNA template activity, autoclaving at 121°C for 80 minutes is recommended.  The presence of air during autoclaving has also been shown to enhance nucleic acid degradation (see Biotechniques, Vol.55, Issue 6, p.296-299, Dec 2013).

High-Temperature Sterilization

An effective method for sterilizing and removing residual nucleic acids from clean glass, ceramic, or steel beads is dry heat treatment:

• 550°F (288°C) for 2 hours, or
• 400°F (204°C) for 4 hours

Bead Reuse

Under normal laboratory use, most beads can be recycled approximately ten times before wear reduces them to an unsuitable size.