Bubble-induced detachment of affinity-adsorbed erythrocytes

It is desirable that cells adsorbed in affinity-separation processes be easily recovered from the adsorption surface, without excessive dilution, once contaminants have been removed. The present study investigates the use of gas-bubble-induced shear stress for the recovery of affinity-adsorbed human erythrocytes. This method has previously been demonstrated to be effective with yeast cells, where it allows cells to be attached, washed and detached under isocratic conditions. Concanavalin A (Con A), used as the binding agent, was attached to the inside of nylon tubes. Whole blood solution, diluted to an erythrocyte concentration of 1×108·ml-1 with PBS, was incubated with the Con A–nylon surface and then washed with PBS prior to elution. To effect elution, air bubbles of known volume were introduced to the buffer feed to the tubes and the effects of bubble size, bubble volume and bubble velocity on detachment being determined. The results obtained showed that the most significant parameter was bubble number, with up to 90% of attached cells being recovered using a five-bubble sequence. Microscopic examination showed no evidence of mechanical damage to the detached cells.