| 摘要 |
Droplets of molten wax or waxy polymer containing a reagent are dropped onto the surface of liquid nitrogen, the droplets remain on the surface until solidified and the droplets are removed from the surface before they sink into the liquid nitrogen to provide beads containing the reagent. The reagent can be any material that can be entrapped in the beads and does not undergo excessive inactivation when the beads are melted by heating to release the reagent. Examples of reagents are heat resistant enzymes, enzyme substrates, metal salts, oligonucleotides, inclusion compounds, surfactants, emulsifiers, antioxidants, stabilizers, drugs, antibiotics, antibodies and antigens. An apparatus for producing the beads contains a plurality of channels through which liquid nitrogen flows from a reservoir. Each channel passes under a dispenser tip from which droplets are formed and released onto the surface of flowing liquid nitrogen. Liquid nitrogen containing the beads flows from each channel into a pipe and then over a separation sieve. The beads can be used in various in vitro chemical, biochemical and immunological reactions including the PCR, where the reagent is released by heating and melting the beads. The beads have all the combined features for commercial use of: (a) spherical shape, (b) uniform, narrow size range (i.e. 5% or less deviation), (c) free of water contamination, (d) contain an aqueous reagent, and (e) can be produced at high speed (i.e. over 1000 per min.).
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