长期以来，超快速冷冻与适当的辅助处理方法结合使用时，已被认为可提供超微结构的保留、可溶性无机和有机物质的定位以及抗原性的保存，优于通过常规化学固定技术和使用冷冻保护剂获得的抗原性.此外，它是目前唯一可用于捕获时间尺度小于几秒的事件的过程。成功的超快速冷冻需要从未固定的未冷冻保护样品中快速提取热量，以至于在电子显微镜分析水平上看不到冰晶损坏。这不是一项微不足道的工作，直到最近，通过超快速冷冻获得的改进通常以降低生产力为代价。然而，在过去几年中，生物样品超快速冷冻方法学的改进和精密设备的引入显着提高了技术应用的便利性和保存完好的样品的产量。 EMS-002 Cryo 工作站允许对生物样品进行可靠的几乎常规冷冻。

Applications:

• Cryo-fixation of virus partials
• Cryo-fixation of isolated or assembled macromolecules
• Cryo-fixation of emulsions paints and polymers
• Cryo-fixation of suspension and tissues for Cryo-techniques such as freeze fracture/etch, freeze drying, freeze substitution.

Advantages:

• Economical, universal application rapid freezing unit.
• Plunge freezing with temperature controlled cryogen.
• Frozen samples handled under cold dry nitrogen atmosphere.
• Rapid set up and easy use.
• Reproducible results.
• High and low set points for cryogen control.

1. Removable Drop Anvil Assemble
2. Specimen Holder
3. Stainless Steel Liquid Nitrogen Dewar
4. Cryogen Temperature Controller
5. Drop Release
6. Removable Cryogen Holder for safe disposal of Cryogen
7. Frozen Specimen Work Station

This allows the user to set desired holding temperatures of the cryogen being used for the freezing process. Easy to use controller also has settable arms to alert the user that the cryogen is warming up and the unit needs attention before the cryogen reach is evaporation temperature.

The EMS-002 achieves ultra-rapid cooling by quenching the sample in liquid propane or other suitable cryogen, cooled to near liquid nitrogen temperature. The EMS-002 accomplishes this by using a stainless steel vacuum insulated Dewar and copper condensation chamber. Liquid nitrogen is poured into the Dewar to a level determined by the user. The initial cooling of the cryogen condensation chamber takes about 15 to 20 minutes.

Gaseous propane is then admitted to the condensation chamber slowly enough to allow it to condense and fill the chamber with liquid propane. The propane is led to cool to near liquid nitrogen temperature supervised by the digital temperature controller while the sample is being prepared for freezing. The device requires only about 10 minutes to cool to operating temperature after the first filling of propane, and less than five minutes after subsequent fillings.

The operator can increase or decrease the rate of cooling by adjusting the level of liquid nitrogen in the Dewar. Heaters built into the chamber wall, powered by the temperature controller, evenly warms the propane above its melting point. The controllers’ temperature is set for the kind of cryogen being used, for instance, 185°C for commercial grade propane.

Chemically pure propane (map. 190°C) can also be used, but it is significantly more expensive than commercial grade propane and confers no particular advantage. Ethane and a non-flammable cryogen, SUVA-124 produced by Dupont can also be used as a cryogen in this instrument. When using flammable cryogens like Propane & Ethane we recommend using the EMS-002 in a fume hood.

The sample can be prepared using any favorite size EM Grid if the system is being used for Cryo-TEM or Panama hat-shaped specimen carriers for Freeze- Fracture or Freeze Substitution. Once the sample is applied to the EM grid for instance, the excess must be carefully blotted away with a small piece of filter paper. Remember, the goal is to form a thin meniscus of specimen across the holes in the grid. Once achieved, insert the specimen holder in the“Drop Anvil” of the EMS-002.

The technique provides higher rates of cooling than can be achieved by plunging the sample into the cryogen by hand because of the high velocity and accuracy the sample enters the cryogen. The optimal plunging speed is approximately 100m per/sec it provides more efficient heat exchange. The freezing is fast enough to capture rapid events and labile structures that are not seen in chemically fixed material. The technique has been applied to many types of specimens: aqueous suspensions and emulsions, tissue culture cells, suspensions of a cells, and tissues. Specimens frozen with the EMS-002 may be freeze fractured, freeze substituted, frozen thin sectioned, or freeze dried. The samples may also be used for Cryo-SEM or Cryo-TEM.

Specifications, EMS-002 Rapid Immersion Freezer

Recycling and Operating Costs

The recycling time of the device is less than three minutes, just long enough for it to be ready when you finish processing the last sample. The operating cost is about 0.47 per sample, depending on the price of liquid nitrogen. The device will operate for about two hours on 10 L of liquid nitrogen, including the initial cool down.