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 .
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on 10/22/2025 has been entered.
Status of Claims
Receipt of Arguments/Remarks filed on 10/22/2025 is acknowledged. Claims 1-2, 5, 8-15, and 17-22 are pending. Claims 1-2, 5, and 8-9 have been amended. Claims 3-4, 6-7, and 16 have been canceled. Claims 10-15 and 17-22 are withdrawn.
Withdrawn Objections and Rejections
The objection to claim 2 is withdrawn given the amendment filed 10/22/2025.
The rejection of claims 3-4 and 8-9 under 35 U.S.C. § 112(a) is withdrawn in view of Applicant arguments filed 10/22/2025 and the cancelation of claims 3-4.
The rejection of claims 1-6 and 8-9 under 35 U.S.C. § 112(b) is withdrawn in view of the amendment filed 10/22/2025.
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.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
Claims 1-2, 5, and 9 are rejected under 35 U.S.C. 103 as being unpatentable over Yang et al., Acs applied materials & interfaces; 10(39):33493-506 in view of Kim et al., Biomaterials; 178:401-12; Syed et al., Nanomedicine: Nanotechnology, Biology and Medicine; 14(7):2191-203; and Gattás-Asfura et al., ACS applied materials & interfaces; 5(20):9964-74.
Regarding claim 1, Yang teaches an enzymatically disulfide-crosslinked chitosan (CS) and hyaluronic acid (HA) layer-by-layer assembled hydrogel for controlled release of protein (Yang “Abstract”). Yang teaches that this hydrogel is multilayered, with at least three alternating layers of chitosan and hyaluronic acid (Yang Scheme 1; p. 33498 Section 3.2). Yang teaches that these layers are enzymatically crosslinked with horseradish peroxidase (HRP) to form a covalently crosslinked hydrogel (Yang p. 33494 first full para.). Yang teaches that CS and HA are natural polysaccharides which are widely used in biomedical applications due to excellent biocompatibility, nontoxicity, and biodegradability (Yang p. 33494 para. 2). Yang teaches that layer-by-layer assembly allows for control of factors such as composition, thickness, shape, and size (Yang p. 33493 para. 1).
Regarding claim 5, Yang teaches that the hydrogel structure comprises at least five alternating layers of chitosan and hyaluronic acid (Yang Scheme 1; p. 33498 Section 3.2).
Yang does not teach that the hydrogel structure is configured to encapsulate β-cells, that the CS and HA are phenol-functionalized, that the layers are crosslinked by tyrosinase to form aryloxy bonds between adjacent layers, or a thickness of 50-500 nm.
Regarding claim 1, Kim teaches hydrogels created with tyrosinase-mediated crosslinking (Kim “Abstract”). Kim teaches that crosslinking reactions of based on oxidation of phenolic groups can be facilitated by a variety of strategies, including chemical oxidation via sodium periodate (NaIO4) or enzymatic activation via horseradish peroxidase (HRP), but these approaches have limitations for practical applications due to the cytotoxicity and pH dependency
of chemical reagents, as well as the fact that only phenol coupling is available for crosslinking (Kim p. 401 para. 1). Kim teaches that tyrosinase, which oxidizes phenols, is a promising alternative, and teaches a tyrosinase derived from Streptomyces avermitilis which has superior reactivity compared to other previously used tyrosinases (Kim pp. 401-402 “Introduction” para. 2-3). Kim teaches hydrogels fabricated by the site-directed coupling of tyramine-conjugated hyaluronic acid and gelatin with this tyrosinase (Kim “Abstract”). The tyrosinase is not cytotoxic, and the tyrosinase crosslinking is fast and enhances the physical properties and adhesive strength of the hydrogel (Kim “Abstract”; p. 406 first partial para.; p. 419 “Conclusions”). Kim teaches that tyrosinase crosslinked hydrogels can be developed as robust tools for surgical glue and localized delivery of cells of biomacromolecules (Kim p. 419 “Conclusions”).
Regarding claim 2, Kim teaches that the phenol moiety is tyramine (Kim “Abstract”).
Regarding claim 9, Kim teaches that the molecular weight of HA used in the hydrogel is 40-64 kDa (Kim p. 402 Section 2.1). When claimed ranges "overlap or lie inside the ranges disclosed by the prior art" and even when the claimed ranges and prior art ranges do not overlap but are close enough that one skilled in the art would have expected them to have similar properties, a prima facie case of obviousness exists. See MPEP 2144.05(1).
Regarding claim 1, Syed teaches a chitosan and poly(sodium styrene sultanate) (PSS) encapsulation layer for encapsulating islets, which include β and α cells (Syed "Abstract"; pg. 2192 col. 1 lines 1-5). Syed teaches that the structure is multilayered, consisting of alternating chitosan and PSS layers to encapsulate the islets, with up to 9 layers, using electrostatic binding (Syed pg. 2192 "Multilayer-by-layer nano-encapsulation"). Syed teaches that the encapsulation coating is 104.2 nm thick ("Abstract"). Syed teaches that the hydrogel encapsulates β-cells and blocks immune cells from accessing the β-cells while allowing diffusion of insulin (Syed "Abstract", pg. 2199-2200 "Discussion" para. 1, pg. 2201 first full para.). Syed additionally teaches that the encapsulation layer protects the β-cells from cytokine induced toxicity (Syed p. 2197 first partial para.).
Regarding claim 1, Gattas-Asfura teaches layer-by-layer encapsulation of pancreatic islets (Gattas-Asfura “Abstract”). Gattas-Asfura teaches that typically, islets are encapsulated within microscale hydrogel-based beads, on the order of 600−1000 μm, but imposing large barriers between the cell surface and its environment commonly leads to impairment of cellular function and responsiveness and cellular encapsulation via layer-by-layer (LbL) film deposition is a highly desirable technique, wherein the chemical and physical properties of the coating can be precisely tailored at the nanometer scale, resulting in ultrathin, conformal coatings (Gattas-Asfura p. 9964 para. 2). Gattas-Asfura teaches that a variety of intermolecular interactions can be employed to facilitate layer formation, such as electrostatic, covalent, hydrogen-bonding, and molecular recognition, and that the most common coating strategy, electrostatic complexation, exhibits major drawbacks when applied to encapsulating viable cells, including cytotoxicity of cationic polymers and long-term instability of the resulting coating (Gattas-Asfura p. 9964 para. 2). Gattas-Asfura teaches that the stability and homogeneity of LbL coatings can be enhanced through the incorporation of interpolymer covalent bonding (Gattas-Asfura p. 9964 para. 3). Gattas-Asfura teaches that the thickness of the multilayer coating, which allows for insulin diffusion, is 70-100 nm (Gattas-Asfura p. 9971 para. 2; p. 9973 first partial para.; Fig. 8B).
It would have been obvious to a skilled artisan, before the effective filing date, to modify the teachings of Yang and utilize phenol-functionalized CS and HA to create a hydrogel with covalently crosslinked layers using tyrosinase. Kim teaches that tyrosinase crosslinking is an alternative approach for the hydrogel crosslinking method taught by Yang, using HRP, and thus it would be obvious that a tyrosinase-mediated covalent crosslinking method could be utilized to create a CS/HA hydrogel as taught by Yang, and that the use of tyrosinase for the crosslinking reaction would necessarily result in the formation of aryloxy bonds between adjacent layers. It would further be obvious to phenol-functionalize CS and HA, as tyrosinase requires a phenol group such as tyramine for crosslinking, and Kim teaches tyramine-conjugated HA.
It would have been obvious to a person having ordinary skill in the art that a multilayered hydrogel comprising at least three alternating layers of phenol-functionalized CS and HA, crosslinked by tyrosinase, could be configured for encapsulation of cells, including β-cells. Both Syed and Gattas-Asfura teach multilayered hydrogel structures for islet encapsulation, which includes β-cells. Both of these references teach that the multilayered hydrogel allows for selective diffusion of insulin, and Syed further teaches that a nanoencapsulation structure comprising chitosan inhibits infiltration of immune cells and cytokines. Thus, it would have been obvious that a multilayered hydrogel structure as taught by Yang and Kim, utilizing CS and HA which are known to be biocompatible and non-cytotoxic, could be configured for encapsulation of β-cells.
A person of ordinary skill in the art would have been motivated to modify the hydrogel structure of Yang to incorporate phenol-functionalized CS and HA crosslinked by tyrosinase, because Kim teaches that HRP-mediated crosslinking has limitations for practical applications due to the cytotoxicity and pH dependency of chemical reagents, and that tyrosinase is non-cytotoxic and results in faster gelation and enhanced physical properties and adhesive strength of the hydrogel (Kim “Abstract”; p. 406 first partial para.; p. 419 “Conclusions”). Thus, it would be considered advantageous to adapt the HRP crosslinked hydrogel taught by Yang to the improved tyrosinase crosslinked hydrogel using phenol-functionalized CS and HA.
A skilled artisan would have been motivated to configure such a hydrogel for the encapsulation of β-cells with diffusion of insulin and inhibition of immune cell and cytokine infiltration, because administering encapsulated β-cells is a promising therapeutic approach for patients with type 1 diabetes (Syed p. 2192 first partial para.).
Syed teaches a multilayered hydrogel with electrostatic binding between layers. A skilled artisan would have been motivated to utilize an enzyme crosslinked hydrogel such as that taught by Yang and Kim for β-cell encapsulation because Gattas-Asfura teaches that electrostatic binding has major drawbacks when applied to encapsulating viable cells, including cytotoxicity of cationic polymers, and that the stability and homogeneity of LbL coatings can be enhanced through the incorporation of interpolymer covalent bonding (Gattas-Asfura p. 9964 para. 2). Thus, it would be considered advantageous to instead utilize a multilayered hydrogel that is enzymatically covalently crosslinked, as taught by Yang and Kim, for the purpose of β-cell encapsulation.
A person having ordinary skill in the art would have additionally been motivated to adapt the hydrogel of Yang to have a thickness in the range of 50-500 nm, as taught by Syed and Gattas-Asfura, as a nanoencapsulation layer of this thickness is effective in allowing the diffusion of insulin from the encapsulated cells, which is necessary for therapeutic use. Both Syed and Gattas-Asfura teach that microscale encapsulation is less effective in allowing for cellular function and insulin diffusion in encapsulated β-cells, making it useful to utilize a layer-by-layer strategy to develop a thin hydrogel at the nanometer scale (Syed p. 2200 para. 2; Gattas-Asfura p. 9964 para. 2). Therefore, a skilled artisan would recognize the benefit of creating a hydrogel with a thickness in this nanoscale range for use in β-cell encapsulation.
A skilled artisan would have a reasonable expectation of success in modifying the hydrogel of Yang to incorporate phenol-functionalized CS and HA crosslinked by tyrosinase, because Kim teaches that this is a promising and effective alternative to HRP crosslinking in a HA hydrogel. A skilled artisan could therefore expect that a CS and HA hydrogel crosslinked by tyrosinase could be successfully obtained. A person having ordinary skill in the art could expect success in utilizing the hydrogel for β-cell encapsulation with diffusion of insulin and inhibition of immune cells and cytokines, because Syed teaches a chitosan-based multilayered hydrogel for this purpose, and Gattas-Asfura teaches that it is beneficial to utilize covalently crosslinked layered hydrogels for this purpose, such as the hydrogel taught by Yang and Kim. Thus, a skilled artisan could expect that a covalently crosslinked CS/HA hydrogel with a thickness of 50-500 nm could be configured for encapsulation of β-cells and insulin diffusion.
Claims 8 is rejected under 35 U.S.C. 103 as being unpatentable over Yang, Kim, Syed, and Gattás-Asfura as applied to claims 1-2, 5, and 9 above, and further in view of Zhang et al., Carbohydrate polymers; 186:82-90.
Yang, Kim, Syed, and Gattas-Asfura teach the cell encapsulation layer according to claim 1 as set forth above.
These references do not teach that the molecular weight of phenol-functionalized chitosan is 15-310 kDa.
Regarding claim 8, Zhang teaches a chitosan and HA hydrogel for pH sensitive
drug encapsulation and release (Zhang "Abstract"). Zhang teaches chitosan with a molecular
weight of 8.75x104 Da, or 87.5 kDa (Zhang pg. 83 Section 2.1). When claimed ranges "overlap or lie inside the ranges disclosed by the prior art" and even when the claimed ranges and prior art ranges do not overlap but are close enough that one skilled in the art would have expected them to have similar properties, a prima facie case of obviousness exists. See MPEP 2144.05(1).
It would have been obvious to a skilled artisan, before the effective filing date, to
combine the teachings of these references and use chitosan with a molecular weight
in a range taught by Zhang. While Yang is silent regarding the molecular weight of chitosan in the hydrogel, a skilled artisan would have been motivated to use phenol-functionalized chitosan with molecular weights in a range as taught by Zhang in a hydrogel structure as taught by Yang with a reasonable expectation of success, given the successful incorporation of chitosan having this molecular weight in a hydrogel for drug encapsulation as taught by Zhang. As it is known that chitosan with a molecular weight in the claimed range can be successfully incorporated into a hydrogel structure for therapeutic use, a skilled artisan could expect to successfully incorporate these elements into a multilayered hydrogel for cell encapsulation as taught by Yang, Kim, Syed, and Gattas-Asfura.
Response to Arguments
Rejection under 35 U.S.C. 112
Applicant’s arguments, filed 10/22/2025, with respect to claims 3-4 and 8-9 rejected under 35 U.S.C. § 112(a) have been fully considered and are persuasive. The rejection of claims 3-4 and 8-9 under 35 U.S.C. § 112(a) has been withdrawn.
The rejection of claims 1-6 and 8-9 under 35 U.S.C. § 112(b) is withdrawn in view of claim amendments and the cancelation of claims 3-4 and 6.
Rejection under 35 U.S.C. 103
Applicant’s arguments, filed 10/22/2025 have been fully considered, and in light of amendments to the claims, the rejections of claims 1-6 under 35 U.S.C. § 103 over Syed and Bi; and of claims 8-9 under 35 U.S.C. § 103 over Syed, Bi, and Zhang have been withdrawn. However, upon further consideration, new grounds of rejection of claims 1-2, 5, and 8-9 are made under 35 U.S.C. § 103 as set forth above. Given these new grounds of rejection, the arguments presented regarding claims 1-6 and 8-9 rejected under 35 U.S.C. § 103 are moot.
Conclusion
Claims 1-2, 5, and 8-9 are rejected. No claims are allowed.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to EMILY F EIX whose telephone number is (571)270-0808. The examiner can normally be reached M-F 8am-5pm ET.
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/EMILY F EIX/Examiner, Art Unit 1653
/JENNIFER M.H. TICHY/Primary Examiner, Art Unit 1653