Macroreticulate buffers: a novel approach to pH control in living systems.

It is possible to control the pH of growing living systems in vitro by adding, to the growth media, macroreticulate buffers, i.e. amphoteric resins made with buffering and titrant groups simultaneously affixed to the matrix. Such beads possess a very precise isoelectric point (pI) and are able to maintain the solutions' pH close to their pI values for extended growth periods. These pearls are made of a neutral polyacrylamide backbone containing up to 200 mM grafted weak acrylamido acids and bases. It is possible to produce such buffers with any desired pH value in the pH 2.5-11 scale. An example is given of conditioning the pH of endive plants grown hydroponically.