       NOTE: This disposition is nonprecedential.


  United States Court of Appeals
      for the Federal Circuit
                ______________________

            ENZO LIFE SCIENCES, INC.,
                    Appellant

                           v.

      BECTON, DICKINSON AND COMPANY,
                   Appellee

                  UNITED STATES,
                      Intervenor
                ______________________

                 2018-1232, 2018-1233
                ______________________

    Appeals from the United States Patent and Trademark
Office, Patent Trial and Appeal Board in Nos. IPR2016-
00820, IPR2016-00822.
                 ______________________

               Decided: August 16, 2019
                ______________________

   JUSTIN P.D. WILCOX, Desmarais LLP, New York, NY,
argued for appellant. Also represented by KERRI-ANN
LIMBEEK, KEVIN KENT MCNISH.

    THOMAS SAUNDERS, Wilmer Cutler Pickering Hale and
Dorr LLP, Washington, DC, argued for appellee. Also rep-
resented by WILLIAM G. MCELWAIN, HEATHER M. PETRUZZI;
2          ENZO LIFE SCIENCES, INC. v. BECTON, DICKINSON AND
                                                    COMPANY


NANCY SCHROEDER, Los Angeles, CA; OMAR KHAN, New
York, NY.

     DENNIS FAN, Appellate Staff, Civil Division, United
States Department of Justice, Washington, DC, argued for
intervenor. Also represented by KATHERINE TWOMEY
ALLEN, SCOTT R. MCINTOSH, JOSEPH H. HUNT; THOMAS W.
KRAUSE, JOSEPH MATAL, FARHEENA YASMEEN RASHEED, Of-
fice of the Solicitor, United States Patent and Trademark
Office, Alexandria, VA.
                   ______________________

    Before LOURIE, O’MALLEY, and CHEN, Circuit Judges.
LOURIE, Circuit Judge.
     Enzo Life Sciences, Inc. appeals from two final written
decisions of the United States Patent and Trademark Of-
fice (“PTO”) Patent Trial and Appeal Board (“the Board”)
holding various claims of U.S. Patent 7,064,197 (“the ’197
patent”) unpatentable as anticipated or obvious. See Ho-
logic, Inc. v. Enzo Life Scis., Inc., No. IPR2016-00820, 2017
WL 4339646 (P.T.A.B. Sept. 28, 2017) (“’820 Decision”); Ho-
logic, Inc. v. Enzo Life Scis., Inc., No. IPR2016-00822, 2017
WL 4407743 (P.T.A.B. Oct. 2, 2017) (“’822 Decision”). The
PTO intervened to defend the constitutionality challenge
to inter partes review (“IPR”) proceedings as applied to pa-
tents issued before the enactment of the America Invents
Act (“AIA”), Pub. L. No. 112-29, 125 Stat. 284 (2011). For
the following reasons, we affirm.
                       BACKGROUND
    Deoxyribonucleic acid (“DNA”) and ribonucleic acid
(“RNA”) are nucleic acids made of a series of nucleotides.
A nucleotide is composed of a sugar, a phosphate, and a
nitrogenous base. DNA has four nitrogenous bases: ade-
nine (A), guanine (G), cytosine (C), and thymine (T). RNA
also has the bases adenine (A), guanine (G), and cyto-
sine (C), but contains uracil (U) instead of thymine (T). A
ENZO LIFE SCIENCES, INC. v. BECTON, DICKINSON AND             3
COMPANY


polynucleotide refers to multiple nucleotides linked to-
gether in a chain. Two strands of polynucleotides can bind
to one another, i.e., hybridize, through hydrogen bonding
between complementary nucleotides known as Watson-
Crick base pairing: bases T or U pair with A, and G pairs
with C. A strand of nucleotides that is not hybridized to
another strand is said to be single-stranded, while two
strands hybridized to each other are said to be double-
stranded.
     Enzo owns the ’197 patent directed to “the detection of
genetic material by polynucleotide probes.” ’197 patent
col. 1 ll. 23–24. The invention leverages hybridization
techniques to detect the presence of an analyte, which may
be “a DNA or RNA molecule,” “a molecular complex,” or “a
biological system containing nucleic acids, such as a virus,
a cell, or group of cells.” Id. col. 1 ll. 39–42. A polynucleo-
tide probe that is complementary to a target analyte will
hybridize with it and is thereby used to detect that ana-
lyte’s presence. See id. col. 2 ll. 37–63. According to the
invention, the analytes to be detected are “fixed . . . in hy-
bridizable form to [a] non-porous solid support.” Id. col. 13
ll. 63–67; see also id. col. 5 ll. 58–60. The specification also
discloses that a “technique for improving the fixing or uni-
formity of the plastic surface for fixing DNA involves treat-
ment of the surface with polylysine.” Id. col. 11 ll. 37–39.
    Independent claim 1 is representative of the claims
challenged in IPR2016-00820 (“the ’820 IPR”) and inde-
pendent claim 17 is representative of the claims challenged
in IPR2016-00822 (“the ’822 IPR”):
    1. A non-porous solid support comprising one or
    more amine(s), hydroxyl(s) or epoxide(s) thereon,
    wherein at least one single-stranded nucleic acid is
    fixed or immobilized in hybridizable form to said
    non-porous solid support via said one or more
    amine(s), hydroxyl(s) or epoxide(s).
Id. col. 13 ll. 63–67 (emphases added).
4         ENZO LIFE SCIENCES, INC. v. BECTON, DICKINSON AND
                                                   COMPANY


    17. An array comprising various single-stranded
    nucleic acids fixed or immobilized in hybridizable
    form to a non-porous solid support.
Id. col. 15 ll. 51–53 (emphases added).
    Hologic, Inc. filed two petitions for IPR of the ’197 pa-
tent. During both proceedings, Becton, Dickinson, & Com-
pany (“Becton”) moved to join as a co-petitioner, and the
Board granted the motions. See Joinder Order at 2, Ho-
logic, Inc. v. Enzo Life Scis., Inc., No. IPR2016-00820
(P.T.A.B. Mar. 27, 2017), Paper No. 32; Joinder Order at 2,
Hologic, Inc. v. Enzo Life Scis., Inc., No. IPR2016-00822
(P.T.A.B. Apr. 5, 2017), Paper No. 31. The Board instituted
trial on all eight grounds of unpatentability across the two
IPRs, which all rely on Fish1 or VPK 2 as the primary refer-
ence.
     The Board determined that all the challenged claims
were unpatentable as anticipated by Fish or rendered ob-
vious by Fish alone or in combination with other prior art
references. ’820 Decision, 2017 WL 4339646, at *11–15;
’822 Decision, 2017 WL 4407743, at *10–15. The Board
next determined that VPK qualified as a prior art refer-
ence. ’820 Decision, 2017 WL 4339646, at *15–18; ’822 De-
cision, 2017 WL 4407743, at *15–18. The Board found that
the ’197 patent could not claim priority from its original
parent application’s filing date of January 27, 1983,



    1    Falk Fish & Morris Ziff, A Sensitive Solid Phase
Microradioimmunoassay for Anti-Double Stranded DNA
Antibodies, 24 Arthritis and Rheumatism 534–43 (Mar.
1981), J.A. 1266–75 (“Fish”).
    2    A.C. van Prooijen-Knegt et al., In Situ Hybridiza-
tion of DNA Sequences in Human Metaphase Chromosomes
Visualized by an Indirect Fluorescent Immunocytochemical
Procedure, 141 Experimental Cell Research 397–407 (Oct.
1982), J.A. 1288–98 (“VPK”).
ENZO LIFE SCIENCES, INC. v. BECTON, DICKINSON AND            5
COMPANY


because that application did not provide written descrip-
tion support for the claimed “non-porous solid support.”
See, e.g., ’197 patent col. 13 l. 63. Instead, the Board deter-
mined that the ’197 patent could only claim priority from
the 1983 application’s child continuation-in-part applica-
tion, which was filed on May 9, 1985. VPK was publicly
available as of October 1982, more than a year before the
critical date of May 9, 1985, and thus qualified as prior art.
See 35 U.S.C. § 102(b) (2006). The Board then concluded
that all the challenged claims were anticipated by VPK or
would have been obvious over VPK in combination with
other prior art references.          ’820 Decision, 2017 WL
4339646, at *19–24; ’822 Decision, 2017 WL 4407743, at
*20–23.
     Enzo appeals. The PTO intervened pursuant to 35
U.S.C. § 143 to defend against Enzo’s constitutionality
challenge to IPRs as applied to the ’197 patent because it
issued on June 20, 2006, which is before the enactment of
the AIA in 2011. Enzo argues that constitutes a violation
of the Fifth Amendment. Before this case was argued, Ho-
logic moved to withdraw as a party to this appeal, and this
court granted the motion. See Enzo Life Scis., Inc. v. Bec-
ton, Dickinson & Co., Nos. 2018-1232, 2018-1233 (Fed. Cir.
Apr. 25. 2019), ECF No. 74. Becton remains as appellee.
We have jurisdiction under 28 U.S.C. § 1295(a)(4)(A).
                         DISCUSSION
    We review the Board’s legal determinations de novo,
and the Board’s factual findings underlying those determi-
nations for substantial evidence. Belden Inc. v. Berk-Tek
LLC, 805 F.3d 1064, 1073 (Fed. Cir. 2015). A finding is
supported by substantial evidence if a reasonable mind
might accept the evidence to support the finding. Consol.
Edison Co. v. NLRB, 305 U.S. 197, 229 (1938).
    Anticipation is a question of fact that we review for sub-
stantial evidence. In re Rambus, Inc., 753 F.3d 1253, 1256
(Fed. Cir. 2014). A prior art document may anticipate a
6          ENZO LIFE SCIENCES, INC. v. BECTON, DICKINSON AND
                                                    COMPANY


claim if it describes every element of the claimed invention,
either expressly or inherently. Husky Injection Molding
Sys. Ltd. v. Athena Automation Ltd., 838 F.3d 1236, 1248
(Fed. Cir. 2016). Whether there are inherent teachings in
a prior art reference is a question of fact. See In re Napier,
55 F.3d 610, 613 (Fed. Cir. 1995).
     Obviousness is a question of law based on underlying
factual findings, including “the scope and content of the
prior art, differences between the prior art and the claims
at issue, the level of ordinary skill in the pertinent art, and
any objective indicia of non-obviousness.” Randall Mfg. v.
Rea, 733 F.3d 1355, 1362 (Fed. Cir. 2013) (citing KSR Int’l
Co. v. Teleflex Inc., 550 U.S. 398, 406 (2007)).
                  I. ANTICIPATION BY FISH
     The Board determined that claims 1, 6, 8, 9, 12–16, 27,
32–34, 41, 61–63, 69, 70, 72–74, 79, 100, 191, 193, 194, 212,
213, 219, 222, 225–227, 230, 233, and 236 in the ’820 IPR
and claims 17, 19, 25, 105, 106, 114, 116, 119, 128, 129,
150, 152, 178, 180, 186, and 187 in the ’822 IPR were an-
ticipated by Fish. ’820 Decision, 2017 WL 4339646, at *11–
12; ’822 Decision, 2017 WL 4407743, at *10–11. Fish
teaches a microradioimmunoassay for detecting antibodies
that bind to double-stranded DNA (“dsDNA”). See J.A.
1266. It further notes the use of poly-L-lysine (“PLL”) “to
facilitate the binding of pure dsDNA to plastic surfaces.”
Id. Fish also discloses experiments using single-stranded
DNA (“ssDNA”) in the form of a mixture of synthetic poly-
mers deoxyadenosine (“poly-dA”) and deoxycytidine (“poly-
dC”) or “denatured calf thymus DNA.” J.A. 1268.
    All of the challenged independent claims in both the
’820 IPR and ’822 IPR require the single-stranded nucleic
acid to be “fixed or immobilized in hybridizable form” (the
“hybridizable form limitation”). See, e.g., ’197 patent col.
13 l. 65, col. 15 l. 52. The Board construed “hybridizable
form” to mean “capable of binding through Watson-Crick
base pairing,” adopting the parties’ agreed-upon
ENZO LIFE SCIENCES, INC. v. BECTON, DICKINSON AND           7
COMPANY


construction. ’820 Decision, 2017 WL 4339646, at *5 (em-
phasis added). 3 The Board further clarified the construc-
tion in its final written decisions to mean that “it has bases
available for base-pairing.” Id. at *6.
     Based on its construction, the Board found that Fish
disclosed the hybridizable form limitation. The Board
found that Fish teaches ssDNA bound to the PLL-coated
wells. See id. at *8. The Board further found that being
capable of hybridizing is the inherent result of ssDNA be-
ing fixed to PLL-treated non-porous solid supports. See id.
at *10–11. The Board rejected Enzo’s argument that Fish
failed to disclose hybridization and found that “actual hy-
bridization is not a requirement of any challenged claim.”
Id. at *10. The claims only recite “hybridizable form,” and
the Board noted that the parties’ stipulated construction
required that the single-stranded nucleic acid be “capable
of binding through Watson-Crick base pairing” and did not
require “actual hybridization.” Id. (citations omitted). The
Board thus concluded that the challenged claims were an-
ticipated by Fish. Id. at *11–12.
    On appeal, Enzo argues that Fish does not disclose nu-
cleic acid hybridization, but instead describes “binding ra-
dioactively-labeled antibodies” to dsDNA. Appellant’s Br.
24 (emphasis omitted). Moreover, Enzo contends, as it did
before the Board, that the nucleic acids in Fish did not ac-
tually hybridize in any of the experiments, and thus the
finding that Fish discloses hybridization lacks substantial
evidence. According to its expert, Dr. Buck, the fact that a
single-stranded nucleic acid exists does not mean it is in
hybridizable form. For example, Dr. Buck testified that “a
nucleic acid may be ‘restricted by the bonds formed be-
tween the nucleic acid and the support’ or inhibited by


    3   The claim construction discussions of the two
Board opinions are identical. Thus, citations regarding the
Board’s claim construction will only be to the ’820 Decision.
8          ENZO LIFE SCIENCES, INC. v. BECTON, DICKINSON AND
                                                    COMPANY


‘entanglement of the nucleic acid strands themselves,
which may form loops and coils, called secondary struc-
tures, restricting the diffusion of other nucleic acid strands
available for hybridization.’” Id. at 25 (quoting J.A. 3630–
31 ¶ 95, 5605–06 ¶ 95). Enzo also argues that Dr. Nelson,
the petitioners’ expert, failed to apply the modified claim
construction and thus his testimony cannot constitute sub-
stantial evidence for the Board’s findings.
    Becton responds that the Board correctly found that
Fish inherently discloses the hybridizable form limitation.
Relying on Dr. Nelson’s testimony, Becton argues that the
positively-charged amines on the surface of the solid sup-
port coated with PLL, as disclosed in Fish, will bond with
the negatively-charged phosphate groups in the DNA back-
bone leaving the bases free to hybridize. Becton criticizes
Enzo for “deliberately sabotaging the experiment” in order
to describe a situation where someone using Fish’s PLL
binding chemistry would not create a hybridizable single-
stranded nucleic acid. Appellee’s Br. 37. Becton contends
that inherency cannot be defeated by “interfer[ing] with
the natural result of a process.” Id. at 38.
     We agree with Becton that Fish’s disclosure of a ssDNA
bound to a solid support coated with PLL inherently dis-
closes that the single-stranded nucleic acid is in hybridiza-
ble form. “A reference includes an inherent characteristic
if that characteristic is the ‘natural result’ flowing from the
reference’s explicitly explicated limitations.” Eli Lilly &
Co. v. Barr Labs., Inc., 251 F.3d 955, 970 (Fed. Cir. 2001)
(quoting Cont’l Can Co. USA, Inc. v. Monsanto Co., 948
F.2d 1264, 1269 (Fed. Cir. 1991)).
    Here, substantial evidence supports the Board’s find-
ing that the single-stranded nucleic acid of Fish is inher-
ently hybridizable. The Board reasonably relied on
testimony from both experts that a characteristic of single-
stranded nucleic acids is that their bases are available to
pair with complementary bases through Watson-Crick
ENZO LIFE SCIENCES, INC. v. BECTON, DICKINSON AND             9
COMPANY


pairing. See ’820 Decision, 2017 WL 4339646, at *11 (citing
J.A. 891 ¶ 64); ’822 Decision, 2017 WL 4407743, at *9; see
also J.A. 874–75 ¶ 24, 891 ¶ 64 (Dr. Nelson’s testimony);
J.A. 3705–06 ¶ 189 (Dr. Buck’s testimony). That is what a
single-stranded nucleic acid does in the presence of comple-
mentary bases. Unless purposely prohibited, the binding
capability is inherent in the nature of a single-stranded nu-
cleic acid. The Board’s finding that Fish’s disclosure of a
ssDNA fixed to a PLL-treated support inherently teaches
the hybridizable form limitation is thus based on substan-
tial evidence.
     Enzo also argues that in the ’822 IPR, the Board erred
in finding that Fish disclosed an “array” of “single-stranded
nucleic acids.” See, e.g., ’197 patent col. 15 ll. 51–53. All of
the challenged independent claims in the ’822 IPR recite
an “array” of “single-stranded nucleic acids.” See, e.g., id.
The Board construed “array” to include “an orderly group-
ing or arrangement of wells or depressions.” ’822 Decision,
2017 WL 4407743, at *4. The Board then found that Fish
teaches this limitation because “it discloses microtitration
trays having wells of ssDNA.” Id. at *7 (citing J.A. 1268).
     Enzo contends that Fish fails to disclose an “array” of
“single-stranded nucleic acids.” See, e.g., ’197 patent col. 15
ll. 51–53 (emphasis added). According to Enzo, the Board
erred in reading the term “array” in isolation from “single-
stranded nucleic acids,” and thus erred in finding that a
container with wells or depressions without any nucleic ac-
ids would meet the claim language.
    Becton responds, and we agree, that the Board’s find-
ing was supported by substantial evidence. Fish describes
supports having rows of wells coated with ssDNA. See J.A.
1268. The Board also credited Dr. Nelson’s testimony that
Table 1 in Fish provides evidence that the ssDNA bound
effectively to the PLL-coated wells of the microtitration
tray. ’822 Decision, 2017 WL 4407743, at *7 (citing J.A.
1268). That constitutes substantial evidence to support the
10         ENZO LIFE SCIENCES, INC. v. BECTON, DICKINSON AND
                                                    COMPANY


Board’s finding that Fish teaches an “array” of “single-
stranded nucleic acids.” See, e.g., ’197 patent col. 15 ll. 51–
53.
    Enzo does not raise any arguments with respect to any
other claim limitation, nor does it separately argue the de-
pendent claims. Thus, the dependent claims stand or fall
together with the independent claims. See In re Kaslow,
707 F.2d 1366, 1376 (Fed. Cir. 1983). We therefore con-
clude that the Board did not err in finding that Fish antic-
ipates claims 1, 6, 8, 9, 12–16, 27, 32–34, 41, 61–63, 69, 70,
72–74, 79, 100, 191, 193, 194, 212, 213, 219, 222, 225–227,
230, 233, and 236 in the ’820 IPR and claims 17, 19, 25,
105, 106, 114, 116, 119, 128, 129, 150, 152, 178, 180, 186,
and 187 in the ’822 IPR.
        II. OBVIOUSNESS GROUNDS BASED ON FISH
    The Board determined that claims 31, 64, 68, 101, 192,
and 195 in the ’820 IPR and claims 130, 131, 151, and 154
in the ’822 IPR would have been obvious over Fish. ’820
Decision, 2017 WL 4339646, at *12–14; ’822 Decision, 2017
WL 4407743, at *11–14. Those claims add one of the fol-
lowing limitations: “wherein said nucleic acid comprises a
nucleic acid sequence complementary to a nucleic acid se-
quence of interest sought to be identified, quantified or se-
quenced,” see, e.g., ’197 patent col. 17 ll. 1–4; or “wherein
said nucleic acid is RNA,” see, e.g., id. col. 18 ll. 38–39; or
“wherein said nucleic acids comprise a gene sequence or
pathogen sequence,” id. col. 22 ll. 42–43. Enzo does not
separately argue the challenged dependent claims and re-
lies on the arguments it raised for anticipation by Fish.
Thus, for the same reasons that Fish anticipates the afore-
mentioned claims, we also hold that Fish renders obvious
claims 31, 64, 68, 101, 192, and 195 in the ’820 IPR and
claims 130, 131, 151, and 154 in the ’822 IPR.
    The Board next determined that claims 38, 78, and 218
in the ’820 IPR and claims 113 and 185 in the ’822 IPR
ENZO LIFE SCIENCES, INC. v. BECTON, DICKINSON AND          11
COMPANY


would have been obvious over Fish and Gilham; 4 and
claims 120 and 189 in the ’822 IPR would have been obvi-
ous over Fish, U.S. Patent 3,572,892 (“Metzgar”), and
Sato. 5 Enzo argues that the Board’s findings of a motiva-
tion to combine Fish and Gilham, and Fish, Metzgar, and
Sato, are not based on substantial evidence. We take the
arguments asserted for each ground in turn.
          A. Obviousness over Fish and Gilham
    The Board determined that claims 38, 78, and 218 in
the ’820 IPR and claims 113 and 185 in the ’822 IPR would
have been obvious over Fish and Gilham. ’820 Decision,
2017 WL 4339646, at *14–15; ’822 Decision, 2017 WL
4407743, at *14–15. The challenged claims add the limita-
tion “wherein said fixation or immobilization to said non-
porous solid support is covalent.” See, e.g., ’197 patent col.
17 ll. 24–26 (emphasis added). Gilham teaches a method
of covalently binding RNA to cellulous supports. See J.A.
1592–93. The Board found that a person of ordinary skill
in the art would have been motivated, with a reasonable
expectation of success, to apply Gilham’s method of cova-
lently binding RNA to Fish’s non-porous supports, such as
the microtitration plates, “because covalent binding pro-
vides a stronger linkage between the immobilized nucleic
acids and the solid substrate.” ’820 Decision, 2017 WL
4339646, at *15 (internal citation omitted). 6



    4   P.T. Gilham, Immobilized Polynucleotides and Nu-
cleic Acids, Immobilized Biochemicals and Affinity Chro-
matography 173–85 (1974), J.A. 1592–1604 (“Gilham”).
     5  Chikako Sato et al., Cell Surface Charge and Cell
Division in Escherichia coli after X Irradiation, 87 Radia-
tion Research 646–56 (1981), J.A. 4422–32 (“Sato”).
     6  The analyses of Fish and Gilham are identical in
the two Board opinions. Thus, citations will only be to the
’820 Decision.
12        ENZO LIFE SCIENCES, INC. v. BECTON, DICKINSON AND
                                                   COMPANY


    Enzo argues that the Board failed to identify why a per-
son of ordinary skill would have been motivated to use the
covalent binding method for RNA in Gilham with the pro-
cedures for using DNA of PLL-coated plates to detect anti-
bodies described in Fish. Moreover, according to Enzo, not
only was there insufficient motivation to combine, but
there would not have been an expectation of success. Enzo
contends that Gilham teaches away from the use of non-
porous supports like those in Fish, and that Gilham’s cova-
lent binding would likely negatively affect the nucleic
acid’s ability to hybridize.
    Becton responds that the Board’s finding of a motiva-
tion to combine Fish and Gilham was supported by sub-
stantial evidence. We agree. Dr. Nelson, whom the Board
credited, explained that both Fish and Gilham disclose nu-
cleic acids bound to solid support surfaces with amine
groups. See id. at *13–14. The Board then found that a
person of ordinary skill in the art would have been moti-
vated to use the covalent binding from Gilham on Fish’s
non-porous solid supports. See id. at *15. We also agree
with Becton that Enzo’s teaching away arguments improp-
erly attack the references individually. See In re Merck &
Co., 800 F.2d 1091, 1097 (Fed. Cir. 1986) (“Non-obvious-
ness cannot be established by attacking references individ-
ually where the rejection is based upon the teachings of a
combination of references.”). However, as the Board deter-
mined, it is the combined teachings of Gilham’s chemistry
for binding RNA in hybridizable form and Fish’s methods
of attaching nucleic acids to non-porous supports that ren-
der the claims obvious. See ’820 Decision, 2017 WL
4339646, at *15. Accordingly, the Board did not err in hold-
ing that claims 38, 78, and 218 in the ’820 IPR and claims
113 and 185 in the ’822 IPR would have been obvious over
Fish and Gilham.
ENZO LIFE SCIENCES, INC. v. BECTON, DICKINSON AND           13
COMPANY


      B. Obviousness over Fish, Metzgar, and Sato
     The Board determined that claims 120 and 189 in the
’822 IPR would have been obvious over Fish, Metzgar, and
Sato. ’822 Decision, 2017 WL 4407743, at *13–14. The
challenged claims add the limitation “wherein said non-po-
rous solid support comprises one or more hydroxyls.” See,
e.g., ’197 patent col. 21 ll. 10–12 (emphasis added).
Metzgar teaches a “multiple well tissue culture microscope
slide” where the microscope slide is “glass or other trans-
parent material.” Metzgar col. 1 l. 2, col. 2 ll. 28–29. Sato
discloses treating glass slides with PLL. See J.A. 4423. Dr.
Nelson testified that “glass necessarily includes hydroxyl
groups.” ’822 Decision, 2017 WL 4407743, at *14 (citing
J.A. 5789 ¶ 83 (“The glass slides of . . . Metzgar necessarily
include hydroxyl groups, because that is a known property
of glass.”)). The Board determined, based on Dr. Nelson’s
testimony, that a person of ordinary skill in the art would
have been motivated to use the glass trays from Metzgar
“as an alternative to Fish’s polyvinyl trays.” Id. (citing J.A.
5789 ¶ 83). In combination with Sato’s teaching of treating
glass slides with PLL, the Board concluded that the chal-
lenged claims would have been obvious over Fish, Metzgar,
and Sato. Id.
     Enzo argues that the Board failed to identify why a per-
son of ordinary skill in the art would have been motivated
to substitute glass plates for the polyvinyl microtitration
trays disclosed in Fish. According to Enzo, the Board erred
in failing to credit Dr. Buck’s uncontested testimony that a
person of ordinary skill would not combine those references
because they would not work for their intended purposes.
    Becton responds that substantial evidence supported
the Board’s finding of a motivation to combine Fish,
Metzgar, and Sato, and we agree. The Board found that
glass slides having wells or depressions were well-known
at the time of the invention. See id. The Board further
found, based on Dr. Nelson’s testimony, that a person of
14        ENZO LIFE SCIENCES, INC. v. BECTON, DICKINSON AND
                                                   COMPANY


ordinary skill in the art would have been motivated to im-
mobilize nucleic acids using the methods described in Fish
on the glass slides disclosed in Metzgar. See id. Addition-
ally, the Board found that Sato teaches “treatment of glass
slides with PLL prior to fixing cells on the slides.” Id. The
Board ultimately credited Dr. Nelson’s testimony that a
person of ordinary skill in the art would have been moti-
vated to perform the nucleic acid immobilization procedure
disclosed in Fish on the glass slides in Metzgar treated
with PLL as disclosed in Sato. Id. The Board’s finding of
a motivation to combine was thus based on substantial ev-
idence. Accordingly, the Board did not err in determining
that claims 120 and 189 in the ’822 IPR would have been
obvious over Fish, Metzgar, and Sato.
    In conclusion, we determine that the Board did not err
in holding that claims 1, 6, 8, 9, 12–17, 19, 25, 27, 31–34,
38, 41, 61–64, 68–70, 72–74, 78, 79, 100, 101, 105, 106, 113,
114, 116, 119, 120, 128–131, 150–152, 154, 178, 180, 185–
187, 189, 191–195, 212, 213, 218, 219, 222, 225–227, 230,
233, and 236 of the ’197 patent are invalid as anticipated
by Fish or obvious over Fish alone or in combination with
other prior art references.
                     III. OTHER ISSUES
    Enzo argues that the Board erred in finding that VPK
qualifies as prior art, and thus the claims are not unpatent-
able as anticipated or obvious over grounds that include
VPK. Because we have determined that the Board did not
err in concluding that all of the challenged claims are un-
patentable on grounds based on Fish, we need not reach
the arguments involving VPK. See Oral Arg. at 12:14–
12:49, 25:58–26:11, Enzo Life Scis., Inc. v. Becton, Dickin-
son & Co., Nos. 2018-1232, 2018-1233 (Fed. Cir. July 9,
2019), http://oralarguments.cafc.uscourts.gov/default.aspx
?fl=2018-1232.mp3.
    Enzo also argues that the IPR process as applied retro-
actively to patents that issued before the enactment of the
ENZO LIFE SCIENCES, INC. v. BECTON, DICKINSON AND        15
COMPANY


AIA violates the Fifth Amendment. We recently addressed
this issue in Celgene Corp. v. Peter, No. 18-1167, 2019 WL
3418549, at *12–16 (Fed. Cir. July 30, 2019), which is now
precedent that governs this case. Celgene held that “retro-
active application of IPR proceedings to pre-AIA patents is
not an unconstitutional taking under the Fifth Amend-
ment.” Id. at *16. Accordingly, we hold that the retroactive
application of IPR proceedings to the ’197 patent, which is-
sued before the enactment of the AIA, is not an unconstitu-
tional taking under the Fifth Amendment.
                       CONCLUSION
    We have considered Enzo’s remaining arguments but
find them unpersuasive. For the foregoing reasons, we af-
firm the decisions of the Board.
                       AFFIRMED
