Sample Preparation Equipment
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Specialist: |
| Descriptions | |
| Equipment |
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Specialist: |
| Descriptions | |
| Equipment |
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The Reichert UltraCut S is a state-of-the-art ultramicrotome system featuring
user-friendly controls, precise knife and sample movements, excellent and highly
versatile lighting, and a variety of sample holder options for semi-thin and
ultra-thin sectioning of resin-embedded samples.
The Model FC S is a cryo-ultramicrotome system specifically designed for routine ultrathin frozen sectioning when coupled to the UltraCut S ultramicrotome. A cryo-chamber surrounding the sectioning area is cooled continuously by liquid nitrogen pumped from a Dewar flask. The automatic pumping system ensures a stable low temperature environment around the frozen specimen. The temperature of the knife, specimen, and cryo-chamber atmosphere can be individually controlled and then continuously regulated by the cryo control unit, which also regulates the liquid nitrogen pumping system. At any time during sectioning, the operator can monitor these temperatures on the display. The Reichert UltraCut S in the Shepherd Labs Facility is normally configured for cryo-ultramicrotomy (coupled to FC S unit) while the UltraCut S in the BSBE Facility is normally configured for room temperature sectioning. Its FC S unit can be added as needed. Applications:
Ultramicrotomy Services
Ultrathin sectioning (using diamond knife) and subsequent staining of embedded biological specimens, and preparing formvar support films, is available on a fee for service basis. Diamond knives and other specialized tools and equipment ARE NOT provided by the BSBE facility for use by others. |
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The Tousimis Critical Point Drying System is used to complete the dehydration of
biological specimens and other materials from their native hydrated states prior to
observation in the SEM. Water is removed from the samples by passing them
through a series of increasingly concentrated ethanol solutions, and the pure
ethanol-saturated samples are then transferred to the system's high-pressure
chamber where the ethanol is replaced by liquid carbon dioxide. The chamber
temperature is then raised to bring the carbon dioxide saturated samples to the
CO2 critical point; that being the combination of temperature and pressure where
the phase boundary between the liquid and gas phases disappears and the two phases
coexist. The chamber pressure is then vented very slowly, allowing the CO2
to leave the sample in the gas phase, but without surface tension effects that
would otherwise cause damage to sample ultrastructure. This semi-automated
system is reliable and easy to operate.
Applications:
Operating Instructions (pdf) |
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The DV-502A system consists of a conventional diffusion pump and oil-filled rotary
pump vacuum system with a 12" bell jar chamber and a variety of electrode assemblies
and feedthroughs to permit:
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The VCR sputtering system deposits extremely thin (~1-2 nm) and fine-grained ~1-4
nm) coatings of platinum, tungsten, carbon, etc. coatings to samples for SEM
observation. The target material is bombarded by a beam of ionized argon gas
accelerated to approximately 9 kV. The ejected target material then impacts
the sample surface which is rotated through a variety of angles during the coating
process. The coating accumulates at approximately 0.1 to 0.2 nm per minute
and can be carefully controlled and easily reproduced.
Operating Instructions (pdf) |
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The HPM 010 High Pressure Freezer allows specimens up to 0.6 mm thick, with a total
volume of ~ 1 mm3, to be vitrified (producing microcrystalline or amorphous
ice) at the relatively slow rate of freezing, compared to plunge or slam methods,
of 200°C / second. Samples are vitrified in ~ 30-50 milliseconds by exposing
them to jets of liquid nitrogen at 2100 Bar for ~ 500 milliseconds. The method
is based on an entirely physical phenomenon that lowers the freezing point of
water. Cells and tissues may be frozen without requiring the addition of
chemical cryoprotectants which can introduce artifacts. Physical immobilization
of all cell components by ultrarapid freezing may be vastly superior to conventional
chemical fixation at room temperature because diffusion of various chemical fixatives
through cells and tissues may take minutes to hours, and not all cell components
will react with fixatives at equal rates, or to equal degrees. Thus cell
components may be lost or rearranged. The method may be used to prepare
samples for cryoSEM, for subsequent preparation of freeze-fracture replicas for
TEM, and for freeze-substitution, in which fixatives in organic solvents are
introduced into the cryoimmobilized samples while still at low temperature,
combining chemical fixation and removal of water while preventing collapse and
shrinkage of cell ultrastructure. The high pressure freezing method has also
been successfully applied to non-biological materials such as latex emulsions and
inks for cryoSEM examination.
The instrument is relatively easy to use, reliable, and robust. A variety of specimen carriers are available to permit freezing of specimens ranging from ~ 50 to 600 microns in thickness. |
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| The BAF 060 Freeze-Fracture System can be used to produce high resolution metal replicas of cryoimmobilized emulsions, liquids, gels, cell suspensions, and tissues, for either TEM or cryoSEM applications. Samples may be fractured by using double replication specimen tables or cyro-microtomes. Partial freeze drying or complete freeze drying can also be carried out, and the samples then coated with metal (platinum/carbon; tantalum/tungsten/carbon; platinum/iridium /carbon). Metal evaporation / coating can be done at angles from 0 to 90. "DARS" (Double Axis Rotary Shadowing) is also possible. The evaporation processes are controlled by a quartz crystal thin film monitor. The two stage vacuum system consisting of a turbomolecular pump combined with a membrane pump assures oil-free vacuum load-lock and sample chamber environments. All specimen tables, both electron beam guns, and the knife can be exchanged through one rough vacuum load lock to maintain high vacuum in the main chamber. The vacuum system's control system is designed to prevent the operator from making errors during transfer and processing, and the quick-lock manipulator with integrated movement guide allows error-free and quick specimen transfer. |  |
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