Sample Preparation

The equipment is part of the Electron Microscopy of Soft Matter Laboratory.

CEVS – Controlled Environment Vitrification System

CEVS - Controlled Environment Vitrification System

The CEVS permits cryofixation of hydrated biological and colloidal dispersions and aggregates from a temperature- and saturation-controlled environment. Otherwise, specimens prepared in an uncontrolled laboratory atmosphere are subject to evaporation and heat transfer, which may introduce artifacts caused by concentration, pH, ionic strength, and temperature changes.

This system ensures that a liquid or partially liquid specimen is maintained in its original state while it is being prepared before vitrification and, once prepared, is vitrified with little alteration of its microstructure. A controlled environment is provided within a chamber where temperature and chemical activity of volatile components can be controlled while the specimen is being prepared.

Click here for a full description of the improved sample preparation technique.

Leica EM BAF 060 Freeze-Fracture-Replication and cryo-SEM sample preparation System

Leica EM BAF 060 Freeze-Fracture-Replication and cryo-SEM sample preparation System

After vitrification, the specimen, mounted on a liquid nitrogen-cooled stage, is fractured in the 10-5-10-6 mbar vacuum chamber, either by a double-replica device or by a cooled knife. The fracture surface is then shadowed by Pt/C; for freeze-fracture-replication, it is also backed by a carbon layer. Metal and carbon coating is performed by two adjustable electron-sputtering guns.

The coated sample is removed from the chamber. For cryo-HRSEM, the sample is transferred immediately to the HR-SEM via an evacuated liquid nitrogen cooled shuttle. In the case of freeze-fracture-replication the vitrified sample is dissolves, the replica washed, dried, and then examined by TEM at room temperature.