Prosecution Insights
Last updated: April 19, 2026
Application No. 18/320,218

AMORPHOUS CALCIUM PHOSPHATE GEL, PREPARATION METHOD AND USE THEREOF

Final Rejection §103
Filed
May 19, 2023
Examiner
ROBERTS, LEZAH
Art Unit
1612
Tech Center
1600 — Biotechnology & Organic Chemistry
Assignee
Yunnan Baiyao Group Health Products Co. Ltd.
OA Round
2 (Final)
48%
Grant Probability
Moderate
3-4
OA Rounds
4y 4m
To Grant
85%
With Interview

Examiner Intelligence

Grants 48% of resolved cases
48%
Career Allow Rate
363 granted / 750 resolved
-11.6% vs TC avg
Strong +36% interview lift
Without
With
+36.4%
Interview Lift
resolved cases with interview
Typical timeline
4y 4m
Avg Prosecution
78 currently pending
Career history
828
Total Applications
across all art units

Statute-Specific Performance

§101
0.5%
-39.5% vs TC avg
§103
49.2%
+9.2% vs TC avg
§102
18.1%
-21.9% vs TC avg
§112
16.0%
-24.0% vs TC avg
Black line = Tech Center average estimate • Based on career data from 750 resolved cases

Office Action

§103
DETAILED ACTION Notice of Pre-AIA or AIA Status The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA . Applicants' arguments, filed September 18, 2025, have been fully considered. Rejections and/or objections not reiterated from previous office actions are hereby withdrawn. The following rejections and/or objections are either reiterated or newly applied. They constitute the complete set presently being applied to the instant application. The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action. Claims Claim Rejections - 35 USC § 103 – Obviousness (Maintained Rejection) Claims 1-4 and 6-8 are rejected under 35 U.S.C. 103 as being unpatentable over Li et al. (2003) in view of Sun et al. (2020) in further view of Lendenmann et al. (EP 4014948) and Constantz et al. (US 5,782,971). Li et al. disclose preparation of amorphous calcium phosphate (ACP) in the presence of polyethylene glycol. The calcium phosphate is made by mixing calcium chloride with sodium phosphate. Calcium chloride is placed in solution with PEG and water. The sodium phosphate (0.133 M) is then added to the calcium chloride (0.1 M) solution and a precipitate is formed. PEG is disclosed to stabilize the ACP. It was disclosed that the PEG can modify the surface of the ACP. The ACP should be washed to remove residual PEG. Li et al. differ from the instant claims insofar as it does not disclose the phosphate source is phosphoric acid, the solvent is propylene glycol and aminomethyl propanol is present. Sun et al. disclose making a porous amorphous calcium phosphate for drug delivery. A solution of amorphous calcium carbonate was made. Phosphoric acid was dissolved and added dropwise under vigorous stirring to the calcium carbonate composition to form the calcium phosphate. Generally, it is prima facie obvious to select a known material for incorporation into a composition, based on its recognized suitability for its intended use. See MPEP 2144.07. It would have been obvious to one of ordinary skill in the art prior to filing the instant application to have used phosphoric acid as the phosphate source and add to have added it dropwise to a calcium salt solution to make amorphous calcium phosphate of Li et al. because it is suitable for making amorphous calcium phosphate and adding the acid dropwise is a method for adding an acid to a calcium solution. Li et al. in view of Sun et al. differs from the instant claims insofar as it does not disclose propylene glycol or aminomethyl propanol. Lendenmann et al. disclose composition for remineralizing the teeth. The composition may comprise amorphous calcium phosphate. The composition has a pH ranging from 3 to 8. Bases used to adjust the pH include 2-aminomethylpropanol. The composition also comprises a solvent such as propylene glycol. Constantz et al. disclose calcium phosphate cements comprising amorphous calcium phosphate. The amorphous calcium phosphate is made to form a gel. The amorphous calcium phosphate (ACP) may be either solid or colloidal/gel like compositions. The solid ACP compositions will generally be characterized as precipitated particles, where the particle size will range from 1 to 250 micrometers with the shape of the particles being irregular. For the gel ACP, the gel will typically have a density of less than about 1.5 g/cm.sup.3, usually less than about 1.25 g/cm.sup.3. The molar ratio of calcium to phosphate in the subject ACP compositions will generally range from about 1.5 to 1.8, usually from about 1.6 to 1.7 and more usually from about 1.63 to 1.68. The calcium source solution comprises a water soluble calcium salt, e.g. calcium chloride or calcium nitrate. The salt is usually a salt other than a phosphate. The phosphate source solution comprises a water soluble phosphate salt, such as alkali metal phosphates are employed. Polyols such as propylene glycol do not interfere with calcium formation. The formation of amorphous calcium phosphate is affected by the pH. Therefore, it would have been obvious to one of ordinary skill in the art to have used 2-aminomethylpropanol to adjust the pH of the composition of Li et al. in view of Sun et al. motivated by the desire to achieve the desire pH of amorphous calcium phosphate formation. Further, it would have been obvious to one of ordinary skill in the art to have used propylene glycol in place of polyethylene glycol because it is a solvent that has been taught as an equivalent to polyethylene glycol and because it does not interfere with calcium mineral formation. It would have been obvious to make a gel because it is a form known in the art for amorphous calcium phosphates. In regards to the temperature and rate of adding the phosphoric acid, Generally, differences in concentration or temperature will not support the patentability of subject matter encompassed by the prior art unless there is evidence indicating such concentration or temperature is critical. "[W]here the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation. It would have been obvious to have adjusted the temperature and the rate of adding phosphoric acid to arrive at the conditions recited by the instant claims though routine experimentation by one of ordinary skill in the art in order to yield the desire amorphous calcium phosphate. In regards to claim 8, “even though product-by-process claims are limited by and defined by the process, determination of patentability is based on the product itself. The patentability of a product does not depend on its method of production. If the product in the product-by-process claim is the same as or obvious from a product of the prior art, the claim is unpatentable even though the prior product was made by a different process." See MPEP 2113, I. Therefore the amorphous calcium phosphate of the references meet the limitation of instant claim 8. Response to Arguments The Examiner submits, that in regards to the method of the instant claims not comprising water, the independent claim does not recite this limitation. Therefore the claim read on an aqueous solution as the solvent. Further, the claims do not mention stability in regards to the final product of the method. It is suggested that the claims make clear that the system/procedure is anhydrous since this appears to be an essential part of the claimed method. In regards to Sun, Sun was used for its disclosure of phosphoric acid and how it can be used as a phosphate source to make amorphous calcium phosphate. It further shows that it is known to add phosphoric acid dropwise to a solution. In regards to the calcium, the independent claim does not recite a specific calcium source. Lendenmann et al. were used for their disclosure of 2-aminomethylpropanol, which is used to adjust pH. The pH is important for calcium phosphate formation. In regards to the results, this does appear to be distinct. However, the claims are not commensurate in scope with the claims in regards to the calcium source. Therefore it is not clear if other calcium sources with different solubilities would yield similar results considering different calcium sources have different solubilities and pH values. However, the rejection is withdrawn in regards to claim 5, which recites the calcium sources. Allowable Subject Matter Claim 5 is objected to as being dependent upon a rejected base claim, but would be allowable if rewritten in independent form including all of the limitations of the base claim and any intervening claims. Conclusion Claims 1-4 and 6-8 are rejected. No claims 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. Any inquiry concerning this communication or earlier communications from the examiner should be directed to LEZAH ROBERTS whose telephone number is (571)272-1071. The examiner can normally be reached Monday-Friday 11:00-7:30. 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, Sahana Kaup can be reached at 571-272-6897. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. /LEZAH ROBERTS/Primary Examiner, Art Unit 1612
Read full office action

Prosecution Timeline

May 19, 2023
Application Filed
Jun 14, 2025
Non-Final Rejection — §103
Sep 12, 2025
Response after Non-Final Action
Sep 18, 2025
Response Filed
Jan 11, 2026
Final Rejection — §103 (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

3-4
Expected OA Rounds
48%
Grant Probability
85%
With Interview (+36.4%)
4y 4m
Median Time to Grant
Moderate
PTA Risk
Based on 750 resolved cases by this examiner. Grant probability derived from career allow rate.

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