DETAILED ACTION
The present Office Action is responsive to the Amendment received on February 5, 2026.
Preliminary Remark
The claim set provided in Applicants’ After-Final Amendment received on February 5, 2026 is incomplete. The claim set contains claim listing to claim 16. The total number of claims pending at any prosecution period had been twenty.
In order to pursue compact prosecution, claims 17-20 (not present in the After-Final amendment) have been assumed to be canceled1.
Claims 1, 2, and 4 are pending are under prosecution herein.
Claim Rejections - 35 USC § 103
The rejection of claim 8 under 35 U.S.C. 103 as being unpatentable over Williamss et al. (Nature Methods, July 2006, vol. 3, no. 7, pages 545-550) in view of Colston et al. (WO 2010/036352 A1, published April 1, 2010) and as evidenced by Nakano et al. (Journal of Biotechnology, 2003, vol. 102, pages 117-124), made in the Office Action mailed on November 5, 2025 is withdrawn in view of the Amendment received on February 5, 2026, based on its cancellation.
The Rejection:
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
The rejection of claims 1, 2, and 4 under 35 U.S.C. 103 as being unpatentable over Williamss et al. (Nature Methods, July 2006, vol. 3, no. 7, pages 545-550) in view of Colston et al. (WO 2010/036352 A1, published April 1, 2010) and as evidenced by Nakano et al. (Journal of Biotechnology, 2003, vol. 102, pages 117-124), made in the Office Action mailed on November 5, 2025 is maintained for the reasons of record.
Applicants’ arguments presented in the Amendment received on February 5, 2026 have been considered but they have not been found persuasive for the reasons discussed in the, “Response to Arguments” section.
The Rejection:
With regard to claim 1, Williams et al., the artisans teach a method composition comprising:
an emulsion formed by mixing PCR sample mixture containing one or two or more amplification target DNAs and a pair of forward and reverse primers, and oil containing a surfactant (“[p]repare the oil-surfactant mixture by thoroughly mixing the following … Span 80 [surfactant] … mineral oil”, page 546; “[t]ransfer 400 ml of the oil-surfactant mixture … [p]repare the aqueous phase for the emulsion by mixing … Forward primer … Reverse primer … dNTPs … Pfu Turbo DNA polymerase … Template DNA … [a]dd 200 ml of the aqueous phase to the oil-surfactant mixture … A w/o emulsion is generated containing approximately 108-109 PCR-competent compartments per milliliter of emulsion”, page 546); and
oil applied on the outside of the emulsion at a uniform thickness (“[p]ipet the emulsion into the wells of a PCR plate as 10 aliquots of 50 ml … Overlay the emulsified and nonemulsified reactions with mineral oil.”, page 547).
The aqueous PCR phase is added at 200 ml to the 400 ml of oil/surfactant mixture, which is a 1:2 in ratio (see page 546, step 2 and page 547, step 4).
With regard to claim 2, the PCR sample mixture further comprises one or two or more from DNA polymerase, dNTP, and a buffer (see above).
With regard to claim 8, Nakano et al. evidence that the method of generating emulsion particles as taught by in a publication having the common artisan, Griffiths, results in microdroplets having the diameter of 2 to 10 mm:
“The W/O emulsion is produced by the following process … Griffiths, 1998 … The prepared W/O emulsion is divided in two … W/O emulsion was observed under microscope …” (page 119, 1st column bottom paragraph to page 119, 2nd column, 1st paragraph)
“The water droplet diameter in the W/O emulsion ranged from 2 to 10 mm” (page 121, 2nd column, 2nd full paragraph)
Williams et al. teach a method of producing emulsion compositions as discussed above. Because the claim only recites the intended usage of the method of the composition for being used in a “digital PCR”, absent an actual application that employs the droplets in a digital PCR employing actively distinct mechanisms different from those disclosed by Williams et al., the limitation claims are met.
Williams et al., while explicitly teaching that the surfactant is a non-ionic surfactant, known as SPAN 80, do not explicitly teach that the surfactant is sorbitan monolaurate.
Colston et al. teach a well-known means of generating emulsion particles comprising PCR substrates therein in an immiscible fluid, wherein said immiscible fluid is Tween 20® (which is commercially sold and known as Polysorbate 20, or sorbitan monolaurate).
It would have been prima facie obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to combine the teachings of Williams et al. and Colston et al. and Nakano et al., thereby arriving at the invention as claimed for the following reasons.
The reason to combine the teachings of based on the combination of elements known in the art, which yield no more than a predictable outcome, as discussed by the Supreme Court.
In KSR, the Supreme Court particularly emphasized “the need for caution in granting a patent based on the combination of elements found in the prior art,” Id. at 415, 82 USPQ2d at 1395, and discussed circumstances in which a patent might be determined to be obvious. Importantly, the Supreme Court reaffirmed principles based on its precedent that “[t]he combination of familiar elements according to known methods is likely to be obvious when it does no more than yield predictable results.” Id. at 415-16, 82 USPQ2d at 1395. The Supreme Court stated that there are “[t]hree cases decided after Graham [that] illustrate this doctrine.” Id. at 416, 82 USPQ2d at 1395. (1) “In United States v. Adams, . . . [t]he Court recognized that when a patent claims a structure already known in the prior art that is altered by the mere substitution of one element for another known in the field, the combination must do more than yield a predictable result.”
The art of producing PCR products in emulsion particles has been well-established. In addition, covering the resulting emulsion particles in their immiscible fluid with additional oil, such as mineral oil is also well-known practice, for the purpose of sealing the PCR plate, preventing the reagents from evaporating during temperature fluctuations and inter-compartment contamination, evidenced by Williams et al.
While Williams et al. did not employ sorbitan monolaurate, also known in the art as Polysorbate 20 with the immiscible fluid (i.e., oil) when generating their PCR emulsion products, one of ordinary skill in the art would have been well-aware of other combinations of surfactants which could be combined with the immiscible fluid when generating emulsified droplets for performing PCR.
Indeed, Colston et al. going back over a decade teach the generation of emulsion droplets in an immiscible fluid (i.e., oil) which is mixed with a surfactant, such as Tween 20®, also known in the art as Span 20 (see attached product catalogue from USBio®).
Therefore, one of ordinary skill in the art would have expected that PCR reagents can be emulsified in immiscible fluid, forming a droplet, wherein the immiscible fluid comprises other surfactants known in the art to also be useful, yielding no more than a predictable outcome of producing a plurality of emulsified droplets containing PCR reagents suspended and stabilized in an oil comprising a surfactant known to be commonly employed in the art.
Therefore, one of ordinary skill in the art would have had a reasonable expectation of success at generating emulsion products comprising PCR reagents therein within an immiscible fluid comprising Tween 20® and then applying the mineral oil over them as taught by Williams et al.
Response to Arguments:
Applicants traverse the rejection.
Applicants state that the present invention relates to an emulsion composition for digital PCR that contains sorbitan monolaurate (Span 20) as a surfactant which is defined as having a content ratio of surfactant-containing oil to PCR mixture of 1:0.3-2 (v/v) and the formed particles have a size of 5 to 30 mm, wherein this emulsion composition when contained in a cylindrical plate to which a reaction film is attached is subjected to centrifugation, PCR samples can be uniformly dispersed into a plurality of wells (page 6, Response).
The Office notes that claims are drawn to a product, that is, an emulsion composition. It is not claimed in a container, nor does the claim recite their dispersion into wells. In addition, even if it were to be dispersed into wells, digital PCR conventionally requires that the emulsion droplets be distributed onto a plate comprising a plurality of wells, or by monolayer dispersion in order for each of the emulsion droplets and the presence/absence of signals to be determined for achieving Poisson Distribution.
Applicants discuss the teachings of Williams, Colston, and Nakano and their respective deficiencies in comparison to the claims. However, the Office points out that one cannot show nonobviousness by attacking references individually where the rejections are based on combinations of references. See In re Keller, 642 F.2d 413, 208 USPQ 871 (CCPA 1981); In re Merck & Co., 800 F.2d 1091, 231 USPQ 375 (Fed. Cir. 1986).
The Office asserts that the combination of teachings teach the presently claimed PCR emulsion, that is to say:
I – Williams teach an emulsion composition which is overlaid with mineral oil, said emulsion composition comprising commonly employed contents in a PCR reaction, including at least a primer pair, target DNA, and surfactant:
“[p]repare the oil-surfactant mixture by thoroughly mixing the following … Span 80 [surfactant] … mineral oil”, page 546; “[t]ransfer 400 ml of the oil-surfactant mixture … [p]repare the aqueous phase for the emulsion by mixing … Forward primer … Reverse primer … dNTPs … Pfu Turbo DNA polymerase … Template DNA … [a]dd 200 ml of the aqueous phase to the oil-surfactant mixture … A w/o emulsion is generated containing approximately 108-109 PCR-competent compartments per milliliter of emulsion”, page 546)
“[p]ipet the emulsion into the wells of a PCR plate as 10 aliquots of 50 ml … Overlay the emulsified and nonemulsified reactions with mineral oil.”, page 547).
II – Williams teach that the oil contains a non-ionic surfactant having a volume ratio of 1:2, well within the claimed ratio of 1:0.3 to 2(see page 546, step 2 and page 547, step 4, 200 ml of PCR phase to 400 ml of oil/surfactant).
Applicants’ table shown on page 5 of the response is incorrect in implying none of the artisans teach this limitation. Williams teaches as below:
“1) Prepare the oil-surfactant mixture … 2) Transfer 400 ml of the oil-surfactant mixture to a CryoTube vial … 3) Prepare the aqueous phase for the emulsion … 4) Add 200 ml of the aqueous phase to the oil-surfactant mixture” (pages 546-547)
Since 200 ml of PCR aqueous phrase is added to 400 ml of oil surfactant mixture, that is 200:400, or 1:2 ratio (v/v).
III – Williams teach the PCR sample further comprising one or two more of DNA polymerase, dNTP, and a buffer.
IV – the W/O emulsion dimension is 2 to 10 mm, well within the claimed range of 5 to 30 mm as evidenced by Nakano.
The missing element of the non-ionic surfactant, sorbitan monolaurate, is taught by Colston in the form of Tween 20®, wherein the artisans teach that use of Tween 20® when generating an emulsion particles comprising PCR substrates in an immiscible fluid is known in the art:
“emulsions disclosed herein and/or any phase thereof, may include at least one hydrophilic surfactant, at least one lipophilic surfactant, or a combination thereof. Alternatively, or in addition, the emulsion disclosed herein and/or any phase thereof, may include at least one nonionic (and/or ionic) detergent. Furthermore, an emulsion disclosed herein and/or any phase thereof may include a surfactant comprising polyethyleneglycol, polypropyleneglycol, or Tween 20, among others” (page 20, lines 22-26)
Therefore, contrary to Applicants’ assertion, the combination of the references, together teach all of the recited elements of the claimed composition.
Applicants state that in terms of effectiveness, the emulsion composition for digital PCR according to the above configuration provides: 1) emulsion particles that can be uniformly dispersed into the grid of the reaction film within the above-defined ranges; 2) surfactant does not cause interference with the PCR amplification phenomenon; and 3) reliability of the PCR reaction being improved (page 7, Response).
The Office is not persuaded. As demonstrated above, 1) the size of the emulsion particles generated from aqueous PCR droplets in immiscible oil/surfactant medium is well-within the emulsion particle size as shown by Nakano; 2) uniform distribution of the emulsion particles is obvious when performing dPCR as each droplet must be discrete and the signals produced therefrom detectable and distinguishable from those that do not; 3) the combination of non-ionic surfactants in the immiscible medium (i.e., oil) has been known in the art, with non-ionic surfactants such as Span 80, Tween 20 already being utilized, which, as already demonstrated by Williams, Colston, with little to no interference in PCR reactions being performed inside the emulsion droplets.
With regard to (4), the reliability of PCR reaction capable of being improved, that is a general benefit applicable to any PCR being performed in emulsified droplets, as the droplet provides an isolated compartment from which the reaction can proceed.
“Nakano demonstrated that water in oil (w/o) emulsion PCR (ePCR) method can solve many biases of traditional PCR, among all the compartmentalization of template DNA molecules reducing competition between fragments of different lengths and in different concentrations, thus diminishing the bias for amplifying smaller fragments and increasing the concentration of the initial template DNA …”2 (page 2)
Applicants next state that Span 20 used in an embodiment of their invention, which is suggested by Colston is not predictable as Colston “merely lists numerous types of surfactants without any detailed disclosure of Specific examples where surfactants are actually used in practical embodiments (page 7, Response).
Applicants argue that because the listing of alternative surfactants without any detailed disclosure, one of ordinary skill in the art would not have any motivation or suggestion to necessarily select Span 20 (sorbitan monolaurate, Tween 20) from the listed surfactants for the formation of droplets in digital PCR, as well as going through a trial-and-error process by selecting from the numerous surfactants listed and confirming the effectiveness through countless repetitive experiments (page 8, Response).
These arguments are not persuasive.
Contrary to Applicants’ assertion, Colston does not merely list all possible surfactants.
Colston actually recites that an emulsion may include a surfactant comprising “polyethyleneglycol, polypropyleneglycol, or Tween 20, among others” (page 20, line 26).
Therefore, the artisans do not list all types of surfactants, but particularly points out three of such surfactants.
Therefore, one of ordinary skill in the art would have been suggested to contemplate among known ionic surfactants, the particular three such surfactants as explicitly suggested by Colston, with a reasonable expectation of success.
With regard to predictability, the legal standard for “reasonable expectation of success” is provided by case law and is summarized in MPEP 2144.08, which notes “obviousness does not require absolute predictability, only a reasonable expectation of success; i.e., a reasonable expectation of obtaining similar properties. See, e.g., In re O'Farrell, 853 F.2d 894, 903, 7 USPQ2d 1673, 1681 (Fed. Cir. 1988).”
Lastly, the Office contends that the position taken by the Office is no different from that of Applicants’ own specification wherein the below is stated:
“Any kind of surfactant may be used without limitation as long as an object of the present invention may be achieved. As an example, a non-ionic surfactant, a cationic surfactant, an anionic surfactant, or a mixture of one of two or more selected from these surfactants may be appropriately mixed and used, but the surfactant is not limited thereto” (section [0046], Specification)
Therefore, the suggestion made by Colston is more limited than the suggestion made by Applicants’ own disclosure that appears to recite that any nonionic, but cationic, anionic, or any combination thereof can be considered.
Since Applicants’ own specification does not include exact experimental parameters for each of any nonionic, cationic, anionic, and their combinations, such a suggestion would have included some experimental optimization involving routine parameters.
As to such, MPEP 2144.05(II)(A) discloses that, “differences in concentrations or temperature will not support patentability of subject matter encompassed by prior art unless there is evidence indicating such concentration or temperature is critical,” citing In re Aller, F.2d 454, 456, 105 USPQ 233, 235, (CCPA 1995).
For these reasons, Applicants’ arguments are not found persuasive and the rejection is maintained.
Conclusion
No claims are allowed.
THIS ACTION IS MADE FINAL. Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
Inquiries
Any inquiry concerning this communication or earlier communications from the Examiner should be directed to Young J. Kim whose telephone number is (571) 272-0785. The Examiner can best be reached from 7:30 a.m. to 4:00 p.m (M-F). The Examiner can also be reached via e-mail to Young.Kim@uspto.gov. However, the office cannot guarantee security through the e-mail system nor should official papers be transmitted through this route.
If attempts to reach the Examiner by telephone are unsuccessful, the Examiner's supervisor, Gary Benzion, can be reached at (571) 272-0782.
Papers related to this application may be submitted to Art Unit 1681 by facsimile transmission. The faxing of such papers must conform with the notice published in the Official Gazette, 1156 OG 61 (November 16, 1993) and 1157 OG 94 (December 28, 1993) (see 37 CFR 1.6(d)). NOTE: If applicant does submit a paper by FAX, the original copy should be retained by applicant or applicant’s representative. NO DUPLICATE COPIES SHOULD BE SUBMITTED, so as to avoid the processing of duplicate papers in the Office. All official documents must be sent to the Official Tech Center Fax number: (571) 273-8300. Any inquiry of a general nature or relating to the status of this application should be directed to the Group receptionist whose telephone number is (571) 272-1600.
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/YOUNG J KIM/Primary Examiner
Art Unit 1637 April 4, 2026
/YJK/
1 This assumption is made based on the claim set dated October 22, 2025, where claims 3, 5-7, and 9-20 had been canceled.
2 Iacumin et al. (Microorganisms, 2020, vol. 8, pages 1-11) references the same Nakano reference (of record).
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