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 is addressed in three ways: 1) Buy commercial preloaded microvials or microplates, 2) Utilize a commercially available vial or microplate bead loader or 3) Try a do-it-yourself bead loader as described below. Compared to the expensive first option, Option 2) lowers bead/vial or beads/microplate costs tenfold. Bead loading is acceptably fast. In addition, it gives you control of the kind, size, and number of beads to load. Option 3) is fun to try, low cost, and compared to the totally manual method, can speed 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 microvials and microplates. Some of these suppliers offer a limited variety of prescribed vials containing "magic" combinations of beads targeted to specific samples (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. Tips on bead selection are available at https://biospec.com/beads-guide-lines. Contact Tech Support and you can tell us what you need. 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 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, these loaders are an obvious choice. Compared to Option 1), the purchase cost of the loader will be recovered after loading less than three or four microplates.
Option 3) For the "Do-It-Yourself" person, below are some low-cost ideas and methods -- some originating from our customers -- to speed up the manual 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 (AKA tuberculin syringe). Discard the syringe plunger and cut the barrel with a scalpel or single-edge razor blade to a length that will hold the amount of beads you want to place in the vial or plate well. Push a disc of fine mesh, stainless steel screen all the way down the barrel using a large, flat head nail or a drill bit. If you need this screen, we will send you the disc - no charge). Hook up the nose-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 beaker of beads and suck up a load of beads. Transfer the loaded beads, still under vacuum, to the receiving vial and 'break' the vacuum. The captured beads fall into your receiving vial.
Practical variations include modifying the tubing by drilling a 1/4" hole into its side. Draw up the beads while your finger is covering the hole and unload the beads simply by moving your finger off the hole. No need to turn off the vacuum. Another variation involves using a 'compressed air blow gun' purchased from a hardware store. Connect it to the vacuum line via thick-walled tubing, and connect the nipple end of your custom "bead sucker upper" device to the air gun's outlet. To use it, squeeze the air gun valve to suck up a bead load into your modified plastic syringe, and after positioning the "bead sucker upper" over the microvial, drop the beads into your microvial by releasing (closing) the air gun's valve.
Coming from one of our customers, Ron Moore: Ron's loader is easy to construct but more 'skill-intensive' to use than the above air gun device. He uses a Keck Clamp (AKA Thumb-clamp) to regulate the gravity flow of 0.1 or 0.5 mm diameter beads from a bottle or large funnel, through about one foot of thin-walled, 3/8 inch OD, PVC (Tygon™) tubing and into the vial. You may have seen similar clamps used on hospital IV infusion setups - 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 using a bench-mounted gunpowder loader. It didn't work reliably. The tiny, hard beads soon abraded its moving parts jambed 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 chrome steel. A simple microplate loader for these large beads can be made with a standard capacity (~0.5 ml) 96 well polystyrene microplate. Each well of this shallow plate holds exactly two 6 mm dia beads per well. Transfer the beads by placing a receiving Porvair reinforced 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.
This "fill a microplate with beads and load the beads into another plate" method has been commercialized. See "Fill and Flip" Microplate Bead Loader.