Prosecution Insights
Last updated: April 19, 2026
Application No. 18/009,485

FLUID GEL COMPOSITIONS

Non-Final OA §103§112§DP
Filed
Dec 09, 2022
Examiner
FAN, LYNN Y
Art Unit
1759
Tech Center
1700 — Chemical & Materials Engineering
Assignee
The University of Birmingham
OA Round
1 (Non-Final)
47%
Grant Probability
Moderate
1-2
OA Rounds
3y 9m
To Grant
96%
With Interview

Examiner Intelligence

Grants 47% of resolved cases
47%
Career Allow Rate
221 granted / 472 resolved
-18.2% vs TC avg
Strong +49% interview lift
Without
With
+48.7%
Interview Lift
resolved cases with interview
Typical timeline
3y 9m
Avg Prosecution
50 currently pending
Career history
522
Total Applications
across all art units

Statute-Specific Performance

§101
4.5%
-35.5% vs TC avg
§103
45.5%
+5.5% vs TC avg
§102
11.2%
-28.8% vs TC avg
§112
25.2%
-14.8% vs TC avg
Black line = Tech Center average estimate • Based on career data from 472 resolved cases

Office Action

§103 §112 §DP
DETAILED ACTION The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA . Status of the Claims Claims 6, 13, 16, and 21-22 have been canceled. Claims 1-5, 7-12, 14-15, 17-20, and 23-25 are currently pending. Election/Restrictions Applicant’s election with traverse of Group I, Claims 1-5, 7-12 and 14-15, and of species polyethylene glycol as the microgel-forming polymer, acrylate as the cross-linkable functional group, 2-hydroxy-4’-(2-hydroxyethoxy)-2-methylpropiophenone (Igracure 2959) as the radical initiator, and constant stirring at 100-1000 rpm as the stirring step, in the reply filed on 12/1/2025 is acknowledged. The traversal is on the ground(s) that all groups are linked by a special technical feature. This is not found persuasive because as indicated by the rejections below, the groups do not share the special technical feature which contributes over the prior art at the time the invention was made. The requirement is still deemed proper and is therefore made FINAL. Claims 4-5, 7-8, 17-20, and 23-25 have been withdrawn from further consideration pursuant to 37 CFR 1.142(b), as being drawn to nonelected inventions and species, there being no allowable generic or linking claims. Claims 1-3, 9-12 and 14-15 are being examined in this application, insofar as they read on the elected species of polyethylene glycol as the microgel-forming polymer, acrylate as the cross-linkable functional group, 2-hydroxy-4’-(2-hydroxyethoxy)-2-methylpropiophenone (Igracure 2959) as the radical initiator, and constant stirring at 100-1000 rpm as the stirring step. Claim Rejections - 35 USC § 112 The following is a quotation of 35 U.S.C. 112(b): (b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention. The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph: The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention. Claims 12 and 15 are rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor, or for pre-AIA the applicant regards as the invention. Claim 12, line 4, the recitation of “optionally” is indefinite as it is unclear if the limitation that follows is required to meet the scope of the invention. Claim 15, line 3, the recitation of “optionally” is indefinite as it is unclear if the limitation that follows is required to meet the scope of the invention. Claim Rejections - 35 USC § 103 In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status. 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 of this title, 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. Claims 1-3, 9-10, 12 and 14-15 are rejected under 35 U.S.C. 103 as being unpatentable over Wu et al (Materials and Design. 2018;160:486-495.) in view of Burke et al (Polymers. 2019;11:1339.). The instant claims recite a method of forming a shear-thinning fluid gel composition comprising 0.5 to 20% w/v of a microgel particle-forming polymer dispersed in an aqueous medium, the method comprising the steps of: a) providing a microgel particle-forming polymer, wherein the polymer comprises a plurality of cross-linkable functional groups; b) dissolving the microgel-forming polymer provided in step a) in an aqueous medium at a concentration of 0.5 to 20% w/v to form a polymer solution; c) mixing the polymer solution formed in step b) with a radical initiator; and d) stirring the mixture until gelation is complete; wherein the viscosity and the elastic modulus of the shear-thinning fluid gel composition reversibly reduce when the gel is exposed to shear. Wu teaches a method of forming a shear-thinning fluid gel composition (p.490 col left – para 1), comprising providing polyethylene glycol diacrylate (PEGDA) aqueous solution with different concentrations, e.g., 5.0 wt%, 10.0 wt%, and 15.0 wt% (Table 1), adding 2-hydroxy-4’-(2-hydroxyethoxy)-2-methylpropiophenone with a final concentration of 0.1 wt% (p.487 col right – para 2). Figure 2 shows significant shear-thinning pseudoplastic behavior, with increasing shear rate the bioink showed a decrease in viscosity (p.489 col right – para 4). Wu does not teach stirring (claim 1), specifically constant stirring at 100 to 1000 rpm (claim 15). However, Wu does teach PEG-based hydrogels using 2-hydroxy-4’-(2-hydroxyethoxy)-2-methylpropiophenone as a photo-initiator. Burke teaches PEG-based hydrogels using 2-hydroxy-4’-(2-hydroxyethoxy)-2-methylpropiophenone as a photo-initiator, wherein a mixture comprises a polymer and a photo-initiator is stirred at 200 rpm for 20 min (p.3 para 3). Thus, before the effective filing date of the claimed invention, it would have been obvious to one of ordinary skill in the art to constantly stir a mixture comprises a polymer and a photo-initiator at 100 to 1000 rpm, since such a stir step is routinely practiced in the art of forming PEG-based hydrogels, as evidenced by Burke. Moreover, before the effective filing date of the claimed invention, one of ordinary skill in the art would have been motivated by the cited reference and routine practice to constantly stir a mixture comprises a polymer and a photo-initiator at 100 to 1000 rpm, with a reasonable expectation for successfully forming a shear-thinning fluid gel composition. References cited above do not teach the claimed concentration of photo- initator (claim 14). However, Wu does teach the method comprises adding 2-hydroxy-4’-(2-hydroxyethoxy)-2-methylpropiophenone with a final concentration of 0.1 wt%. Thus, before the effective filing date of the claimed invention, it would have been obvious to one of ordinary skill in the art to optimize the concentration as a matter of routine experimentation. Generally, differences in concentration will not support patentability of subject matter encompassed by the prior art unless there is evidence indicating such concentration is critical. (MPEP 2144.05 II) Moreover, before the effective filing date of the claimed invention, one of ordinary skill in the art would have been motivated by the cited reference and routine practice to optimize the concentration with a reasonable expectation for successfully forming a shear-thinning fluid gel composition. Claim 11 is rejected under 35 U.S.C. 103 as being unpatentable over Wu et al (Materials and Design. 2018;160:486-495.) in view of Burke et al (Polymers. 2019;11:1339.) as applied to claims 1-3, 9-10, 12 and 14-15 above, further in view of Compaan et al (ACS Appl. Mater. Interfaces. 2019;11:5714-5726.). References cited above do not teach the aqueous medium is phosphate buffered saline (claim 11). However, Wu does teach 3D bioprinting (Abstract). Compaan teaches 3D bioprinting (Abstract), wherein a fluid gel is prepared in phosphate buffered saline to prevent osmotic shock to printed cells, stabilize the pH, and match the ionic strength of ink formulations to minimize swelling (p.5716 col left – last para, col right – first para). Thus, before the effective filing date of the claimed invention, it would have been obvious to one of ordinary skill in the art to incorporate phosphate buffered saline, since Wu and Compaan both disclose 3D bioprinting comprises a fluid gel, and Compaan specifically discloses that phosphate buffered saline in 3D bioprinting fluid gels enhances biocompatibility. Moreover, before the effective filing date of the claimed invention, one of ordinary skill in the art would have been motivated by the cited reference to incorporate phosphate buffered saline with a reasonable expectation for successfully forming a shear-thinning fluid gel composition. Double Patenting The nonstatutory double patenting rejection is based on a judicially created doctrine grounded in public policy (a policy reflected in the statute) so as to prevent the unjustified or improper timewise extension of the “right to exclude” granted by a patent and to prevent possible harassment by multiple assignees. A nonstatutory double patenting rejection is appropriate where the claims at issue are not identical, but at least one examined application claim is not patentably distinct from the reference claim(s) because the examined application claim is either anticipated by, or would have been obvious over, the reference claim(s). See, e.g., In re Berg, 140 F.3d 1428, 46 USPQ2d 1226 (Fed. Cir. 1998); In re Goodman, 11 F.3d 1046, 29 USPQ2d 2010 (Fed. Cir. 1993); In re Longi, 759 F.2d 887, 225 USPQ 645 (Fed. Cir. 1985); In re Van Ornum, 686 F.2d 937, 214 USPQ 761 (CCPA 1982); In re Vogel, 422 F.2d 438, 164 USPQ 619 (CCPA 1970); and In re Thorington, 418 F.2d 528, 163 USPQ 644 (CCPA 1969). A timely filed terminal disclaimer in compliance with 37 CFR 1.321(c) or 1.321(d) may be used to overcome an actual or provisional rejection based on a nonstatutory double patenting ground provided the reference application or patent either is shown to be commonly owned with this application, or claims an invention made as a result of activities undertaken within the scope of a joint research agreement. A terminal disclaimer must be signed in compliance with 37 CFR 1.321(b). The USPTO internet Web site contains terminal disclaimer forms which may be used. Please visit http://www.uspto.gov/forms/. The filing date of the application will determine what form should be used. A web-based eTerminal Disclaimer may be filled out completely online using web-screens. An eTerminal Disclaimer that meets all requirements is auto-processed and approved immediately upon submission. For more information about eTerminal Disclaimers, refer to http://www.uspto.gov/patents/process/file/efs/guidance/eTD-info-I.jsp. Claims 1-3, 9-12 and 14-15 are provisionally rejected on the ground of nonstatutory obviousness-type double patenting as being unpatentable over claims 1-4 of co-pending Application No. 18/009,144 (referred to as the ‘144 application) in view of Wu et al (Materials and Design. 2018;160:486-495.) and Compaan et al (ACS Appl. Mater. Interfaces. 2019;11:5714-5726.). Claims 1-4 of the ‘144 application recite a method of forming a shear-thinning fluid gel composition comprising 0.5 to 20% w/v of a microgel particle-forming polymer dispersed in an aqueous medium, the method comprising the steps of: a) providing a microgel particle-forming polymer, wherein the polymer comprises a plurality of cross-linkable functional groups; b) dissolving the microgel-forming polymer provided in step a) in an aqueous medium at a concentration of 0.5 to 20% w/v to form a polymer solution; c) mixing the polymer solution formed in step b) with an agent capable of cross-linking the cross-linkable functional groups of the polymer; and d) stirring the mixture until gelation is complete; wherein the viscosity and the elastic modulus of the shear-thinning fluid gel composition reversibly reduce when the gel is exposed to shear. The microgel particle-forming polymer is a synthetic polymer. The microgel particle-forming polymer is dissolved in the aqueous medium at a concentration of 2 to 8% w/v. The stirring in step d) is carried out at 100 to 1000 rpm. ‘144 application does not teach the microgel particle-forming polymer is a polyethylene glycol comprising acrylate (claims 3 and 9), the aqueous medium is phosphate buffered saline (claim 11), and the radical initiator is 2-hydroxy-4’-(2-hydroxyethoxy)-2-methylpropiophenone (claim 12) at a concentration of 0.01 to 1% v/v (claim 14). Wu teaches a method of forming a shear-thinning fluid gel composition (p.490 col left – para 1), comprising providing polyethylene glycol diacrylate (PEGDA) aqueous solution with different concentrations, e.g., 5.0 wt%, 10.0 wt%, and 15.0 wt% (Table 1), adding 2-hydroxy-4’-(2-hydroxyethoxy)-2-methylpropiophenone with a final concentration of 0.1 wt% (p.487 col right – para 2). In addition, Compaan teaches a fluid gel that is prepared in phosphate buffered saline prevents osmotic shock to printed cells, stabilizes the pH, and matches the ionic strength of ink formulations to minimize swelling (p.5716 col left – last para, col right – first para). Thus, before the effective filing date of the claimed invention, it would have been obvious to one of ordinary skill in the art to incorporate a polyethylene glycol comprising acrylate and 2-hydroxy-4’-(2-hydroxyethoxy)-2-methylpropiophenone to form a shear-thinning fluid gel composition, since such materials have been used to form a shear-thinning fluid gel composition, as evidenced by Wu. Furthermore, before the effective filing date of the claimed invention, it would have been obvious to one of ordinary skill in the art to incorporate phosphate buffered saline, since Wu and Compaan both disclose 3D bioprinting comprises a fluid gel, and Compaan specifically discloses that phosphate buffered saline in 3D bioprinting fluid gels enhances biocompatibility. In addition, before the effective filing date of the claimed invention, it would have been obvious to one of ordinary skill in the art to optimize the concentration as a matter of routine experimentation. Generally, differences in concentration will not support patentability of subject matter encompassed by the prior art unless there is evidence indicating such concentration is critical. (MPEP 2144.05 II) Moreover, before the effective filing date of the claimed invention, one of ordinary skill in the art would have been motivated by the cited references to incorporate a polyethylene glycol comprising acrylate, an optimized amount of 2-hydroxy-4’-(2-hydroxyethoxy)-2-methylpropiophenone, and phosphate buffered saline with a reasonable expectation for successfully forming a shear-thinning fluid gel composition. This is a provisional obviousness-type double patenting rejection because the patentably indistinct claims have not in fact been patented. Conclusion No claims are allowed. Contact Information Any inquiry concerning this communication or earlier communications from the examiner should be directed to LYNN Y FAN whose telephone number is (571)270-3541. The examiner can normally be reached on M-F 7am-4pm. Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Curtis Mayes can be reached on (571)272-1234. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of an application may be obtained from the Patent Application Information Retrieval (PAIR) system. Status information for published applications may be obtained from either Private PAIR or Public PAIR. Status information for unpublished applications is available through Private PAIR only. For more information about the PAIR system, see http://pair-direct.uspto.gov. Should you have questions on access to the Private PAIR system, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative or access to the automated information system, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. /Lynn Y Fan/ Primary Examiner, Art Unit 1759
Read full office action

Prosecution Timeline

Dec 09, 2022
Application Filed
Feb 10, 2026
Non-Final Rejection — §103, §112, §DP (current)

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Study what changed to get past this examiner. Based on 5 most recent grants.

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Prosecution Projections

1-2
Expected OA Rounds
47%
Grant Probability
96%
With Interview (+48.7%)
3y 9m
Median Time to Grant
Low
PTA Risk
Based on 472 resolved cases by this examiner. Grant probability derived from career allow rate.

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