Abstract
It is well known that when blood is drawn through a bare glass cannula or into a glass container, clotting occurs within a very short period of time. On the other hand, if the glass cannula and the container be coated with paraffin so that the blood does not come in contact with the bare glass, clotting may be delayed for hours, or completely inhibited.
Briggs has shown in the preceding communication that a quartz diaphragm may be coated with protein so as to acquire the properties of a pure protein diaphragm. Undoubtedly this is due to the phenomenon of adsorption, possibly in accordance with the Gibbs principle that substances which decrease surface or interfacial tension tend to be adsorbed.
It occurred to us that possibly blood-clotting was dependent upon the adsorption of some constituent from the serum onto a surface, thereby increasing the effective concentration of this constituent and initiating the clotting phenomenon.
Streaming potential measurements showed that a bare glass capillary had a negative ζ-potential of approximately 30 millivolts,∗ whereas the same capillary coated with a thin layer of paraffin had essentially a zero ζ-potential against water. The high ζ-potential would favor electrostatic adsorption of positively charged colloids at the interface of glass-blood serum, and there would be no such tendency for a paraffin-blood serum interface. We accordingly postulate that the initial step in blood-clotting involves a surface concentration of some positively charged constituent, the concentration being brought about by selective adsorption.
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