Capillary tips are small, thin tubes made of glass or plastic thatCapillary tips are small, thin tubes made of glass or plastic that are used in various laboratory applications, such as capillary electrophoresis, liquid chromatography, and DNA sequencing. They are designed to have a very small inner diameter, typically ranging from 5 to 100 micrometers, which allows for the precise control of the flow of liquids through them.
The functionality of capillary tips is based on the principle of capillarity, which is the ability of a liquid to flow in narrow spaces without the assistance of external forces, such as gravity or pressure. When a liquid is placed inside a capillary tip, it forms a meniscus at the open end due to surface tension. The height of this meniscus is determined by the balance between the cohesive forces within the liquid and the adhesive forces between the liquid and the walls of the capillary tip.
In capillary electrophoresis, for example, an electrical field is applied across the ends of the capillary tip, causing charged particles within the liquid to move towards one of the ends. The size and shape of the capillary tip, as well as the properties of the liquid being analyzed, can affect the efficiency and accuracy of the separation process.
In liquid chromatography, capillary tips are used to separate complex mixtures of compounds based on their chemical properties and interactions with the stationary phase within the column. The small inner diameter of the capillary tip allows for high resolution and sensitivity, while the narrow bore ensures that only a small amount of sample is required for analysis.
In DNA sequencing, capillary tips are used to carry out single-molecule real-time (SMRT) sequencing, which involves detecting fluorescently labeled nucleotides as they are incorporated into a growing DNA strand by a polymerase enzyme. The small size of the capillary tip allows for high-resolution imaging of individual DNA molecules, while the narrow bore ensures that only a single molecule can be observed at a time.
Overall, the design and functionality of capillary tips are critical for achieving accurate and reliable results in various laboratory applications.