Bioreactor and bioprocessing are the equipment and the steps with which a medicine is made by living cells and then purified. A bioreactor is the tank in which the cells are grown. Bioprocessing is the whole process: growing the cells, and then separating and cleaning the medicine they make. Medicines made in this way, by living cells rather than by chemistry, are called biologics. Examples are antibodies for cancer and arthritis, insulin and many vaccines.
Why use cells? A biologic is a very large and complex molecule, such as an antibody. Chemists cannot build it step by step in a flask. But a living cell can make it, if the cell is given the gene for it. The cells most used for antibodies come from hamsters and are called CHO cells. Each cell makes a little of the antibody and releases it into the liquid around it.
The cells need exactly the right conditions to grow. The bioreactor keeps the temperature at 37°C. It keeps the acidity, measured as pH, close to 7.0. It bubbles in oxygen, stirs the liquid gently and adds food for the cells. Sensors in the tank measure all of these every few seconds. A control system adjusts them when a reading drifts.
Many bioreactors today are single-use. Instead of a steel tank that must be cleaned and sterilised after every batch, the cells grow inside a large sterile plastic bag held in a steel frame. After the batch, the bag is thrown away. This saves days of cleaning and lowers the risk of one batch contaminating the next.
Take, for example, a company near Bengaluru that makes a biosimilar, a close copy of a biologic whose patent has expired. India is one of the world's largest makers of biosimilars. The company grows CHO cells in a 2,000-litre single-use bioreactor for 14 days. The recipe for each step comes from the plant's manufacturing execution system (MES), which also records every reading. At the end, the liquid is harvested. Filters remove the cells. Then chromatography columns, which separate substances as described in chromatography and mass spectrometry, pull out the antibody and leave the rest behind. More filters remove any viruses. The result is a few kilograms of purified antibody.
The purified medicine is then filled into vials or syringes, which are described in drug delivery devices. Most biologics must be kept cold all the way to the patient, in a cold chain. The same kind of equipment, seen from the factory side, appears in bioprocess and sterilisation equipment.