Prosecution Insights
Last updated: April 19, 2026
Application No. 18/306,986

PREPARATION OF NANO SILVER/DUAL MODIFIED CHITOSAN ANTIBACTERIAL HYDROGEL DRESSING WITH DISCOLORATION EFFECT FOR WOUND INFECTION JUDGEMENT AND HYDROGEL DRESSING PREPARED BY THE SAME

Non-Final OA §103§112
Filed
Apr 25, 2023
Examiner
CRAIG, KAILA ANGELIQUE
Art Unit
1618
Tech Center
1600 — Biotechnology & Organic Chemistry
Assignee
ZHEJIANG UNIVERSITY
OA Round
1 (Non-Final)
33%
Grant Probability
At Risk
1-2
OA Rounds
3y 5m
To Grant
67%
With Interview

Examiner Intelligence

Grants only 33% of cases
33%
Career Allow Rate
20 granted / 60 resolved
-26.7% vs TC avg
Strong +34% interview lift
Without
With
+33.7%
Interview Lift
resolved cases with interview
Typical timeline
3y 5m
Avg Prosecution
49 currently pending
Career history
109
Total Applications
across all art units

Statute-Specific Performance

§101
2.0%
-38.0% vs TC avg
§103
50.1%
+10.1% vs TC avg
§102
16.9%
-23.1% vs TC avg
§112
22.1%
-17.9% vs TC avg
Black line = Tech Center average estimate • Based on career data from 60 resolved cases

Office Action

§103 §112
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 . Status of Claims Examined Herein: 1-5 Priority Acknowledgment is made of applicant's claim for priority under based upon an application filed in CN202111397963.6 on 11/19/2021 and PCT/CN2022/117686 on 9/8/2022. Receipt is acknowledged of certified copies of papers required by 37 CFR 1.55. Information Disclosure Statement The information disclosure statement (IDS) submitted on 4/25/2023 is in compliance with the provisions of 37 CFR 1.97. Accordingly, the information disclosure statement is being considered by the examiner. Drawings The drawings received on 4/25/2023 are accepted. 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 1-5 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 applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention. Claim 1 and 2 recite the steps of preparing dual water-soluble modified chitosan and using said dual water-soluble modified chitosan to prepare a nanosilver/dual water-soluble modified chitosan. Claim 1 and 2 then recite that both the prepared dual water-soluble modified chitosan (“dual chitosan”) and nanosilver/dual water-soluble modified chitosan (“nanosilver/dual chitosan”) are added to a mixture. However, it is unclear how the dual chitosan and the nanosilver/dual chitosan exist separately when added to the mixture, since the dual chitosan is used to prepare the nanosilver/dual chitosan. Specifically, it is unclear whether only a portion of the dual chitosan is used to prepare the nanosilver/dual chitosan. If so, claim 1 and 2 do not recite any steps drawn to portioning the dual chitosan. Alternatively, it is unclear whether the dual chitosan is not fully consumed during the reaction with silver nitrate, so after the reaction nanosilver/dual chitosan and unreacted dual chitosan exist; or another plausible explanation. The specification provides no clarity, as the coexistence of dual chitosan and nanosilver/dual chitosan is also recited in the specification. Further clarification is required. Dependent claims fall therewith. Claim 4 recites the limitation “the zwitterions,” which is interpreted as a plurality of zwitterions. However, claims 1, 2, and 4 seemingly describe only a single zwitterion is used to prepare the claimed hydrogel. The specification also describes a single zwitterion is used to prepare the claimed hydrogel. [Specification, Example 1-3] Thus, it is unclear whether the method allows for only one or a plurality of zwitterions to be used to prepare the claimed hydrogel. If the former, Applicant may consider amending the claim language to recite a “the zwitterion,” in accordance with the single zwitterion recited in claims 1, 2, and 4. Further clarification is required. Claim Rejections - 35 USC § 103 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 factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows: 1. Determining the scope and contents of the prior art. 2. Ascertaining the differences between the prior art and the claims at issue. 3. Resolving the level of ordinary skill in the pertinent art. 4. Considering objective evidence present in the application indicating obviousness or nonobviousness. Claims 1 and 5 are rejected under 35 U.S.C. 103 as being unpatentable over Zheng (Catechol modified quaternized chitosan enhanced wet adhesive and antibacterial properties of injectable thermo-sensitive hydrogel for wound healing, 8/3/2020, Carbohydrate Polymers, Volume 249, 116826), in view of Qiao (CN 108559008, Published 9/21/2018), El-Hady (Antibacterial Properties and pH Sensitive Swelling of Insitu Formed Silver-Curcumin Nanocomposite Based Chitosan Hydrogel, 10/23/2020, Polymers, 12:2451), and Jiang (CN 111154037 A, Published 4/13/2016). With respect to claim 1 and 5, Zheng discloses a method for preparing quaternized/catechol-modified chitosan comprising: carrying out quaternization water-soluble modification on medium molecular weight chitosan, and carrying out catecholamination water-soluble modification to prepare dual water-soluble modified chitosan. [Zheng, Page 2, Col. 2, Paragraph 1-3] Zheng further discloses the method comprises adding the dual water-soluble modified chitosan to a hydrogel, PLEL-nBG. [Zheng, Page 2, Col. 2, Paragraph 5] Zheng does not disclose the chitosan is high molecular weight chitosan or the method further comprises the steps of reducing silver nitrate by using the dual water-soluble modified chitosan to prepare a nano silver/dual water-soluble modified chitosan solution; adding the nano silver/dual water-soluble modified chitosan, curcumin, zwitterion, acrylamide, a cross-linking agent and an initiator into deionized water in sequence, mixing and stirring uniformly, centrifugal de-foaming and casting. However, with respect to claim 1 and 5, Qiao discloses a method comprising carrying out quaternization water-soluble modification on high molecular weight chitosan. [Qiao (Translated), Page 2] Zheng nor Qiao disclose the method further comprises the steps of reducing silver nitrate by using the dual water-soluble modified chitosan to prepare a nano silver/dual water-soluble modified chitosan solution; adding the nano silver/dual water-soluble modified chitosan, curcumin, zwitterion, acrylamide, a cross-linking agent and an initiator into deionized water in sequence, mixing and stirring uniformly, centrifugal de-foaming and casting. However, with respect to claim 1 and 5, El-Hady discloses a method for preparing a chitosan/silver–curcumin nanocomposite hydrogel comprising reducing silver nitrate by using chitosan to prepare a nano silver/chitosan solution; and adding curcumin to the nano silver/chitosan solution. [El-Hady, Page 3, Paragraph 1 and 2] Zheng nor Qiao nor El-Hady disclose the method further comprises adding the nano silver/dual water-soluble modified chitosan, curcumin, zwitterion, acrylamide, a cross-linking agent and an initiator into deionized water in sequence, mixing and stirring uniformly, centrifugal de-foaming and casting. However, with respect to claim 1 and 5, Jiang discloses a method for preparing a hydrogel comprising adding zwitterion (SBMA), acrylamide (Aam), a cross-linking agent (MBAA) and an initiator (ammonium persulfate) into deionized water in sequence, mixing and stirring uniformly, centrifugal de-foaming and casting. [Jiang (Translated), Page 2, Example 1] Modifying the method disclosed by Zheng by replacing the medium molecular weight chitosan with high molecular weight chitosan and additionally performing the steps of reducing silver nitrate by using the dual water-soluble modified chitosan to prepare a nano silver/dual water-soluble modified chitosan solution and further adding said chitosan, curcumin, a zwitterion, an acrylamide, a cross-linking agent and an initiator into deionized water in sequence, mixing and stirring uniformly, centrifugal de-foaming and casting, results in the method of claim 1. The limitation “for preparing a nano silver/dual modified chitosan antibacterial hydrogel dressing with discoloration effect for judging wound infection” recites an intended use. The limitation merely states the purpose or intended use of the invention, rather than any distinct definition of any of the claimed invention’s limitations and is of no significance to claim construction. MPEP 2111.02(II) It would be obvious to one of ordinary skill in the art to modify the method disclosed by Zheng by replacing the medium molecular weight chitosan with high molecular weight chitosan and have a reasonable expectation of success. Zheng discloses a method comprising carrying out quaternization water-soluble modification on medium molecular weight chitosan. Qiao discloses a method comprising carrying out quaternization water-soluble modification on high molecular weight chitosan. So, Qiao establishes that carrying out quaternization water-soluble modification on chitosan can be performed using high molecular weight chitosan. Thus, the combined teachings of Zheng and Qiao suggest that the step of carrying out quaternization water-soluble modification on chitosan in the method disclosed by Zheng can be performed using high molecular weight chitosan. Therefore, it is reasonable to expect the method disclosed by Zheng may be modified by replacing the medium molecular weight chitosan with high molecular weight chitosan. One would have been motivated to do so because the selection of a known material based on its suitability for its intended use is prima facie obvious. MPEP 2144.07 In the instant case, Qiao establishes that carrying out quaternization water-soluble modification on chitosan can be performed using high molecular weight chitosan. Therefore, the selection of high molecular weight chitosan based on its suitability for carrying out quaternization water-soluble modification on chitosan is prima facie obvious. It would be obvious to one of ordinary skill in the art to modify the method disclosed by Zheng by additionally performing the steps of reducing silver nitrate by using the dual water-soluble modified chitosan to prepare a nano silver/dual water-soluble modified chitosan solution and further adding curcumin to said chitosan and have a reasonable expectation of success. Zheng discloses a method for preparing a chitosan hydrogel comprising preparing dual water-soluble modified chitosan solution. El-Hady discloses a method for preparing a chitosan hydrogel comprising preparing chitosan solution and using said chitosan to reduce silver nitrate, thereby forming a nano silver/chitosan solution. El-Hady discloses the method further comprises adding curcumin to the solution. So, El-Hady establishes that in a method for preparing a nano silver/chitosan/curcumin hydrogel comprising preparing a chitosan solution, said chitosan solution may be used to reduce silver nitrate, thereby forming a nano silver/chitosan solution. El-Hady also establishes that curcumin may be added to the formed solution. Thus, the combined teachings of Zheng and El-Hady suggest that the dual water-soluble modified chitosan solution prepared in the method disclosed by Zheng may be used to reduce silver nitrate, thereby forming a nano silver/chitosan solution, and curcumin may be further added to the solution. Therefore, it is reasonable to expect the method disclosed by Zheng may be modified by additionally performing the steps of reducing silver nitrate by using the dual water-soluble modified chitosan to prepare a nano silver/dual water-soluble modified chitosan solution and further adding curcumin to said chitosan. One would have been motivated to do so because it is prima facie obvious to combine references when some advantage or some advantage or expected beneficial result would have been produced by their combination. MPEP 2144(II) In the instant case, El-Hady discloses nano silver/chitosan/curcumin hydrogel exhibits a greater antibacterial activity than chitosan hydrogel. [El-Hady, Pag 12, Table 1] Therefore, one would have been motivated by the expectation that the aforementioned modification could yield a hydrogel that exhibits a greater antibacterial activity than chitosan hydrogel. It would be obvious to one of ordinary skill in the art to modify the method disclosed by Zheng and El-Hady by adding the nano silver/dual water-soluble modified chitosan and curcumin preparation and a zwitterion, an acrylamide, a cross-linking agent and an initiator into deionized water in sequence, mixing and stirring uniformly, centrifugal de-foaming and casting and have a reasonable expectation of success. Zheng and El-Hady disclose a method comprising preparing nano silver/dual water-soluble modified chitosan, adding curcumin to the chitosan, and adding the preparation to a hydrogel. Jiang discloses a method for preparing a hydrogel comprising adding a zwitterion, an acrylamide, a cross-linking agent and an initiator into deionized water in sequence, mixing and stirring uniformly, centrifugal de-foaming and casting. Thus, the combined teachings of Zheng/El-Hady and Jiang suggest the nano silver/dual water-soluble modified chitosan and curcumin preparation disclosed by Zheng/El-Hady may be added to the hydrogel prepared according to the method disclosed by Jiang. Therefore, it is reasonable to expect the method disclosed by Zheng and El-Hady may be modified by adding the nano silver/dual water-soluble modified chitosan and curcumin preparation and a zwitterion, an acrylamide, a cross-linking agent and an initiator into deionized water in sequence, mixing and stirring uniformly, centrifugal de-foaming and casting. One would have been motivated to do so because it is prima facie obvious to combine references when some advantage or some advantage or expected beneficial result would have been produced by their combination. MPEP 2144(II) In the instant case, Jiang discloses the method for preparing a hydrogel produces an amphoteric ion conductive hydrogel endowed with excellent adhesiveness, transparency, force sensitivity, shape memory, biocompatibility and anti-protein adhesiveness. [Jiang (Translated), Page 1, Paragraph 4] Therefore, one would have been motivated by the expectation that the aforementioned modification would yield a chitosan/nano-silver/curcumin hydrogel with excellent adhesiveness, transparency, force sensitivity, shape memory, biocompatibility and anti-protein adhesiveness. Claim 5 is rejected under 35 U.S.C. 103 as being unpatentable over El-Hady, in view of Zheng. With respect to claim 5, El-Hady discloses a nano-silver chitosan antibacterial hydrogel dressing with a discoloration effect. El-Hady also discloses the hydrogel comprises curcumin. [El-Hady, Page 3, Paragraph 1-2] El-Hady does not disclose the chitosan is dual water-soluble modified chitosan. However, Zheng discloses a dual water-soluble modified chitosan antibacterial hydrogel dressing. [Zheng, Page 2, Col. 2, Paragraph 2-3, 5] Modifying the hydrogel dressing disclosed by El-Hady by replacing the chitosan with dual water-soluble modified chitosan, results in the hydrogel dressing of claim 5. The limitation “for judging would infection” recites an intended use. The limitation merely states the purpose or intended use of the invention, rather than any distinct definition of any of the claimed invention’s limitations and is of no significance to claim construction. MPEP 2111.02(II) The limitation “prepared by the method according to claim 1” recites a product by process limitation. The determination of patentability is based on the product itself and not 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. The hydrogel dressing disclosed by El-Hady and Zheng is the same as the claimed product. Therefore, the aforementioned limitation does not limit the claimed hydrogel dressing. MPEP 2113(I-II) It would be obvious to one of ordinary skill in the art to modify the hydrogel dressing disclosed by El-Hady by replacing the chitosan with dual water-soluble modified chitosan and have a reasonable expectation of success. El-Hady discloses an antibacterial hydrogel dressing comprising chitosan. Zheng discloses an antibacterial hydrogel dressing comprising dual water-soluble modified chitosan. So, Zheng establishes that dual water-soluble modified chitosan is suitable for use in an antibacterial hydrogel dressing. Thus, the combined teachings of El-Hady and Zheng suggest that the dual water-soluble modified chitosan disclosed by Zheng may be used in the antibacterial hydrogel dressing disclosed by El-Hady. Therefore, it is reasonable to expect the hydrogel dressing disclosed by El-Hady may be modified by replacing the chitosan with dual water-soluble modified chitosan. One would have been motivated to do so because it is prima facie obvious to combine references when some advantage or some advantage or expected beneficial result would have been produced by their combination. MPEP 2144(II) In the instant case, Zheng discloses dual water-soluble modified chitosan could prove to be beneficial for improving the treatment of clinical wounds especially for complicated skin defects. [Zheng, Page 2, Col. 1, Paragraph 3] Therefore, one would have been motivated by the expectation that replacing the chitosan with dual water-soluble modified chitosan could prove to be beneficial for improving the treatment of complicated skin defects. Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to KAILA A CRAIG whose telephone number is (703)756-4540. The examiner can normally be reached Monday-Friday 0800-1600. 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, Michael Hartley can be reached at 571-272-0616. 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. /K.A.C./ Examiner, Art Unit 1618 /Michael G. Hartley/Supervisory Patent Examiner, Art Unit 1618
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Prosecution Timeline

Apr 25, 2023
Application Filed
Feb 02, 2026
Non-Final Rejection — §103, §112 (current)

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Prosecution Projections

1-2
Expected OA Rounds
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Grant Probability
67%
With Interview (+33.7%)
3y 5m
Median Time to Grant
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