Loading Beads in Vials or Microplates
Loading beads, one deep-well at a time, into a 96 well microplates or a large number of microvials is tedious and time-consuming. This problem can be addressed in three ways: 1) Buy commercial preloaded vials or microplates, 2) Utilize a commercial vial or microplate bead loader or 3) Try a do-it-yourself bead loader. Compared to the expensive first option, Option 2) lowers bead/vial or beads/microplate costs by tenfold. Bead loading is acceptably fast. In addition, it provides control of the kind, size and number of beads used. Option 3) is fun to try, low cost, and compared to the totally manual method, still speeds up bead loading significantly.
Option 1) Clearly, this is the easiest solution but it is the most costly by far. BioSpec Products and several other commercial sources sell pre-loaded vials and microvials. Most of these suppliers offer a limited variety of prescribed vials containing "magic" combinations of beads targeted to specific sample types (bacteria, tissue, soil, etc). BioSpec believes the choice of bead size, bead type and bead quantity per vial or deep well is best left to the end-user. Some tips on bead selection are available at https://biospec.com/beads-guide-lines or Tech Support. Tell us what you need and we will give you an attractive quote.
Option 2) BioSpec offers three bead dispensers. All are designed to load 0.4 to 1.0 milliliter quantities of various sized beads into 2 ml microvials or 96 deep-well microplates in one or two simple moves. Each loader differs in its mechanics, throughput and cost. For laboratories having high throughput of samples and a desire to keep consumable costs under control, this is an obvious choice. Compared to Option 1), the cost of the loader will be recovered after loading less than three or four microplates.
Option 3) For the "Do-It-Yourself" person, here are some low-cost ideas and methods for speeding up loading of beads.....
Loading Microvials. If you have a vacuum line in the lab, try making a 'bead sucker upper'. Obtain a 1 ml plastic syringe (also called a tuberculin syringe). Discard the syringe plunger and cut the barrel with a scalpel or single edge razor blade to a length that will contain one ml (or some other lesser volume) of beads. Push a small stainless steel mesh disc all the way down the barrel using a nail, a drill bit or thick wire (contact us and we will provide you with the mesh disc - no charge). Hook up the needle-end of the syringe to some thick-walled tubing and the other end of the tubing to the vacuum line. Dip the modified syringe barrel into a container of beads to suck up a load of beads. Transfer the loaded beads, under vacuum, to a receiving vial and 'break' the vacuum. The beads fall out into your receiving vial.
Practical variations include using thick-walled tubing having a 1/4" hole drilled into its side. Draw up the beads while your finger covers the hole and unload the beads by removing you finger off the hole. Another variation involves using a 'compressed air blow gun' available at hardware stores. Connect it to a vacuum line via some thick-walled tubing, squeeze the air gun valve to draw up the beads into the modified syringe and release the air gun valve to drop the beads into your vial.
Coming from one of our users: Ron Moore's loader is very easy to construct but more 'skill-intensive' to use than the device described above. He uses a Keck Clamp (a.k.a. Thumb-clamp) to regulate the gravity flow of 0.1 or 0.5 mm diameter beads from a bead bottle or large funnel, through about one foot of thin-walled, 3/8 inch OD, PVC (Tygon™) tubing and, finally, into the vial. You may have seen this type clamp used on hospital IV infusion sets - but those clamps are too small for the present application. Cole Parmer Instruments sells one that is large enough: Cat No C-06835-07, at about $5 each.
And, from Cindy Lamb: "We use a separatory funnel to dispense 0.1 mm diameter beads. An open-close-open-close turn of the stopcock was perfect to dispense ~1 ml of the beads."
Cindy's idea prompted us to try a commercial bench-mounted gun powder loader. It didn't work reliably. The tiny, hard beads soon abrade its moving parts and jamb the loader.
Loading Deep-well Microplates with one or two large beads. Some tough plant samples are best homogenized in deep-well microplates using one or two 6.35 mm diameter beads made of glass or steel. A simple microplate loader for these large beads can be made with a standard capacity (~0.5 ml) 96 well polystyrene plate. Each well of this shallow plate holds exactly two 6 mm dia beads per well. Transfer the beads by placing a receiving deep-well microplate, up-side-down, over the steel bead-filled standard microplate and inverting the paired plates. If you want to limit the loader to one bead, decrease the capacity of the standard microplate by gluing a single bead to the bottom of each well, thus leaving space for only one bead.