Appeal No. 1999-1384
Application No. 08/583,912
flow rates to provide optimal reactions times can also be found in Ligler et al.
(‘740)(columns 5-10).” Ligler discloses (column 6, lines 48-54) that:
The flow rate of the liquid stream in the method of this
invention should be between 0.1 and 2.0 milliliters per minute,
preferably between 0.3 and 0.8 milliliters per minute. The optimum
flow rate is such that the residence time of the target on the
exchanger is sufficient to generate displacement of measurable
quantities of labelled antigen in the shortest possible time.
Ligler discloses (column 9, lines 53-54) that “[t]ypical flow rates used with the
system are 0.3-0.8 ml/min, and that “picomoles of antigen can be detected under
continuous flow rates as fast as 0.8 ml/min” (column 10, lines 28-29). However,
the examiner recognizes (Answer, bridging paragraph, pages 4-5) that Ligler’s
exemplified support medium is a sepharose bead. While Ligler discloses other
alternative support media (column 9, lines 6-16), Ligler does not teach a porous
membrane as claimed.
To make up for this deficiency the examiner applies Kidwell. According to
the examiner (Answer, page 5) “Kidwell teaches a displacement assay device
and method wherein the binding elements having labelled analogs of a target
analyte are immobilized on a porous [supporting] membrane.” According to
Kidwell (column 6, lines 22-38):
The semipermeable membrane can be any membrane that,
together with the supporting membrane, regulates the fluid flow
rate so that the proper reactions take place. Preferably, this
interaction time is between about one to about five minutes, with
two minutes being most preferred. Hence, one can vary the pore
size and the area of the supporting and semipermeable
membranes to achieve the proper interaction time. The smaller the
pore size and the smaller the surface area of the membranes, the
longer the interaction time and the greater the sensitivity. Also,
depending upon the pore size of the supporting membrane, an
additional semipermeable membrane may not be required. In the
displacement mode using a nitrocellose [sic] membrane, optimum
performance in both time and sensitivity results from 0.45 µm pore
size, with a three-sixteenth inch diameter membrane and
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