What Is a Microplate?
A microplate, sometimes called a microtiter plate, is a laboratory tool used primarily in biochemical experiments. It consists of multiple transparent wells, functioning similarly to small petri dishes. The design of the wells, including their shape, color, volume, surface material, and coating, varies according to the intended use.
Uses of Microplate
Microplates enable simultaneous experiments across many wells, making them ideal for collecting large amounts of data under consistent conditions. They are used in cell line and microorganism culturing, dilution series measurement, and with microplate readers for absorption and fluorescence detection. Common applications include ELISA (enzyme-linked immunosorbent assay) in biochemistry and clinical testing, and high throughput screening (HTS) in drug discovery. They are also used for direct sample observation under a microscope or for cellular imaging.
Principle of Microplate
Microplates are coated with various materials to facilitate sample adsorption and immobilization. ELISA, involving highly specific antigen-antibody reactions, is a common use. In ELISA, antibodies bind to antigens on the microplate, with the luminescence from an enzyme reaction detectable by a microplate reader. This method allows for the quantitative measurement of trace samples with high sensitivity and without radiation exposure.
Types of Microplate
1. Classification by the Number and Size of Wells
Microplates vary from the standard 96-well plate to versions with 6 to 9,600 wells. The well size inversely correlates with the number of wells.
2. Classification by Well Shape
Wells can be flat-bottomed, round-bottomed, or V-bottomed, each suited for specific applications, such as bottom-reading plate readers, cell culture, or sample collection.
3. Classification by Plate Material
Common materials include polystyrene, polypropylene, and glass, each offering different chemical resistance.
4. Surface Treatment
The non-surface-treated polystyrene surface is hydrophobic and can interact with and immobilize biomolecules with hydrophobic portions, such as antibodies. Some have high-binding surface coatings that enhance binding to hydrophobic molecules, while others have hydrophilic surface (polyethylene oxide-like) coatings to minimize intermolecular interactions.
Others have surface-coated molecular structures (e.g., maleimide or hydroxy groups) that covalently bind to and immobilize specific functional groups of the sample, allowing them to orient and immobilize specific biomolecules.
5. Color
While transparent is standard, black and white plates are used to reduce light scattering in fluorescence and enhance signal-to-noise ratio in luminescence detection, respectively.