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Metabolites are the essential substrates for epigenetic modification enzymes to write or erase the epigenetic blueprint in cells. Hence, the availability of nutrients and activity of metabolic pathways strongly influence the enzymatic function. Recent studies have shed light on the choreography between metabolome and epigenome in the control of immune cell differentiation and function, with a major focus on histone modifications. Yet, despite its importance in gene regulation, DNA methylation and its relationship with metabolism is relatively unclear. In this review, we will describe how the metabolic flux can influence epigenetic networks in innate and adaptive immune cells, with a focus on the DNA methylation cycle and the metabolites S‐adenosylmethionine and α‐ketoglutarate. Future directions will be discussed for this rapidly emerging field.

Novel optically transparent and highly organo-soluble alicyclic polyimides derived from bulky alicyclic diamine containing trifluoromethyl group on either side, 1,1-bis[4(2-trifluoromethyl-4aminophenoxy)phenyl]-4-tert-butylcyclohexane (BTFAPBC), were prepared. All polymers showed excellent solubility in various organic solvents like N-methyl-2-pyrrolidinone (NMP), N,N-dimethyl acetamide (DMAc), N,N-dimethyl formamide (DMF), pyridine, cyclohexanone, and γ-butyrolactone. The cut-off wavelength and 80% transmission wavelength for polyimides ranged from 362 to 407 nm and 436 to 492 nia, respectively. Polyimides with alicyclic tert-butylcyclohexyl cardo and trifluoromethyl substituents exhibited low dielectric constants ranging from 3.38 to 4.07 (at 1 KHz). Inherent viscosities of the polyimides were found to be in the range of 0.52-1.00 dL·g -1 . Polyimides showed glass transition temperatures in the range of 231-262 °C, and possessed a coefficient of thermal expansion (CTE) of 66-79 ppm.°C -1 . Thermogravimetric analyses of the polyimides revealed high thermal stability and decomposition temperature more than 450 °C in nitrogen atmosphere. The 10% weight loss temperature was found to be in the range of 453-544 and 413-502 °C in nitrogen and air atmospheres, respectively. The polyimide films had a tensile strength ranging from 84 to 100 MPa. The elongation at break varied from 6 to 12% and the tensile modulus varied from 1.1 to 2.1 GPa.

A novel organosoluble polynorbornene bearing a polar, pendant, ester-bridged epoxy group [poly(oxiran-2-ylmethyl 2-methylbicyclo[2.2.1]hept-5-ene-2-carboxylate) (polyOMMC)] was prepared via the living ring-opening metathesis polymerization (ROMP) of active norbornenes with a Ru catalyst. PolyOMMC exhibited excellent solubility in a variety of solvents. The number-average molecular weight of polyOMMC linearly increased with the [M]/[I] ratio (where [M] is the monomer concentration and [I] is the initiator concentration), and a narrow polydispersity of 1.09–1.19 was observed; this was considered a living polymerization. When ROMP of oxiran-2-ylmethyl 2-methylbicyclo[2.2.1]hept-5-ene-2-carboxylate with [M]/[I] = 350 was carried out at 30 °C in CH2Cl2, the number-average molecular weight (7.01 × 104; polydispersity index = 1.07) was close to the calculated molecular weight (7.28 × 104), and a diblock copolymer was observed after the addition of another monomer ([M]/[I] = 350) with an increase in the number-average molecular weight (1.60 × 105; polydispersity index = 1.11), which was close to the calculated molecular weight (1.61 × 105). The modified polynorbornenes retained good solubility in methylene chloride, tetrahydrofuran, dimethyl sulfoxide, dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrdione. High-performance polynorbornenes with active epoxy groups could be designed with great potential for applications in photoresists, UV curing, and elastomers. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4428–4434, 2006

Novel star-like polymeric materials with high cis content could be obtained by using α-norbornenyl macromonomers and highly stable macroinitiators derived from an active norbornene derivative [5-(2-bromo-2-methylpropionylaminomethyl)bicyclo[2.2.1]hept-2-ene (NBBrMPAM)], which was synthesized by the reaction of norbornene methylene amine and 2-bromo-2-methylpropionyl bromide. The α-norbornenyl macromonomer (NBPMMA), which is polymethyl methacrylate containing norbornenyl end group, was prepared by atom transfer radical polymerization (ATRP) using NBBrMPAM as an initiator. Star-like polynorbornene with high cis microstructure (cis/trans = 72/28) was obtained directly by ring-opening metathesis polymerization of NBPMMA macromonomer having number molecular weight (Mn) as low as 6.39 × 103. Random ring-opening metathesis copolymerization of NBPMMA and norbornene derivative containing carbazole group (NBCbz) was carried out at 25 °C by using Ru catalyst [(Cy3P)2Cl2Ru = CHPh, Cy = cyclohexyl, Ph = phenyl]. High cis (cis/trans = 63/37) organo-soluble star-like random poly(NBPMMA-co-NBCbz) was successfully obtained with high number-average molecular weight (Mn) of 4.76 × 104 and molecular weight distribution polydispersity index of 1.78. Organo-soluble comb-shaped copolymers with MMA could be successfully obtained using ATRP macroinitiator [poly(HNBBrMPAM)] in diluted macroinitiator solution with a concentration less than 3.64 × 10−2 mol.L−1. This is the first ever attempt to prepare novel star-like organo-soluble polymeric materials with high cis microstructure via the combination of ring-opening metathesis polymerization and ATRP. Multimodification could be considered to be carried out by using the functional bromo group at the end of side chains. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3382–3392, 2006

Diblock copolymers of 5-(methylphthalimide)bicyclo[2.2.1]hept-2-ene (NBMPI) and 1,5-cyclooctadiene were synthesized by living ring-opening metathesis polymerization with a well-defined catalyst {RuCl2(CHPh)[P(C6H11)3]2}. Unhydrogenated diblock copolymers showed two glass transitions due to poly(NBMPI) and polybutadiene segments, such as two glass-transition temperatures at −86.5 and 115.3 °C for poly1a and −87.2 and 115.3 °C for poly1b. However, only one melting temperature could be observed for hydrogenated copolymers, such as 119.8 °C for poly2a and 121.7 °C for poly2b. The unhydrogenated diblock copolymer with the longer poly(NBMPI) chain (poly1a; temperature at 10% mass loss = 400 °C) exhibited better thermal stability than the one with the shorter poly(NBMPI) chain (poly1b; temperature at 10% mass loss = 385 °C). Two kinds of hydrogenated diblock copolymers, poly2a and poly2b, exhibited relatively poor solubility but better thermal stability than unhydrogenated diblock copolymers because of the polyethylene segments. Poly[(hydrochloride quaternized 2-norbornene-5-methyleneamine)-b-butadiene]-1 (poly3a) was obtained after the hydrolysis and quaternization of poly1a. Dynamic light scattering measurements indicated that the hydrodynamic diameters of the cationic copolymer (poly3a) in water (hydrodynamic diameter = 1580 nm without salt), methanol/water (4/96 v/v; hydrodynamic diameter = 1500 nm without salt), and tetrahydrofuran/water (4/96 v/v; hydrodynamic diameter = 1200 nm without salt) decreased with increasing salt (NaCl) concentration. The effect of temperature on the hydrodynamic diameter of hydrophobically modified poly3a was also studied. The inflection point of the hydrodynamic diameter of poly3a was observed at various polymer concentrations around 30 °C. The critical micelle concentration of hydrophobically modified poly3a was observed at 0.018 g dL−1. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2901–2911, 2006

A novel doubly polymerizable functional norbornene, 5-(methacryloyloxyethylamino carboxylmethyl)bicyclo[2.2.1]hept-2-ene (NBMOACM), was prepared. The ring-opening metathesis polymerization (ROMP) of NBMOACM was carried out to prepare polymers with crosslinkable side chains with the Grubbs catalyst. No gel formation occurred during the ROMP of NBMOACM. The 1H NMR spectrum of poly(NBMOACM) showed broad signals between 5.10 and 5.40 ppm, corresponding to the vinyl protons of the cis and trans double bonds of the ring-opened polymer. Increasing the ratio of the monomer concentration to the catalyst concentration resulted in the formation of higher molecular weight polymers. Poly(NBMOACM) was incorporated into poly(methyl methacrylate) [poly(MMA)] to produce AB crosslinked materials. These crosslinked materials [1 wt % poly(NBMOACM), 10% weight loss temperature = 300 °C in air] had higher thermal stability than pure poly(MMA) (10% weight loss temperature = 276 °C in air). © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6287–6298, 2006

The extent of intra- and interchain associations of (un)charged water-soluble monomers in the homogeneous and micellar solutions was studied with steady-state fluorescence spectroscopy. Fluorescence spectroscopic experiments were performed on uncharged (acryl amide) and charged hydrophilic monomers [zwitterionic 3-dimethyl(methacryloyloxyethyl)ammonium propane sulfonate (DMAPS), etc.] with pyrene as a probe. In both the homogeneous and micellar solutions, linear Stern–Volmer plots were obtained that implied that the quenching process can be considered as totally dynamic. The Stern–Volmer constant (KSV) for DMAPS decreased with an increasing dielectric constant of solvent and the concentration of simple electrolyte. An abrupt decrease in KSV was observed in the presence of a small amount of anionic emulsifier [below the critical micelle concentration (cmc)]. The dependence of KSV on pH for DMAPS was described by a curve with a maximum at about pH = 7. This was interpreted in terms of segregation of DMAPS and the variation of a optimal microenvironment for the probe and quencher with pH. The quenching rate in the micellar solutions strongly increased above the cmc but was lower than that in the homogeneous solutions. In the micellar solutions (above the cmc), the microenvironment for an interaction between the probe and quencher was suggested to be the whole microdroplet. The dependence of KSV on pH for DMAPS is described by a curve with a maximum at about pH = 9.3. The synergistic effect arises from the segregation of charged quencher molecules within the microdroplets. The complex (or strong interaction) between quencher and additive(s) is supposed to increase the dynamic nature of microdroplets that provides an optimal microenvironment for probe and quencher. A good coemulsifier, however, removes quencher from the interface and creates a barrier for entering monomer (quencher) into the core of micelles; therefore, quenching is depressed. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 571–581, 2003

Naphthalene-labeled cationic poly(hydrochloride-quaternized 2-norbornene-5-methyleneamine), poly(HCQNBMA)/NA, has been prepared by ring-opening metathesis polymerization (ROMP), using {RuCl 2 (CHC 6 H 5 )-[P(C 6 H 11 ) 3 ] 2 } as a catalyst in methylene chloride, followed by hydrogenation, hydrolysis, and quaternization. The effect of salt addition on the aqueous solution properties of poly(HCQNBMA)/NA was examined in terms of reduced viscosity, surface tension and fluorescence studies. The reduced viscosity of poly(HCQNBMA)/NA is dependent on the type and concentration of salts added. The viscosity behavior of cationic poly(HCQNBMA)/NA is in contrast with polybetaines. An increase in KCl concentration causes the reduced viscosity of poly(HCQNBMA)/NA to decrease at constant poly(HCQNBMA)/NA concentration. The general shape of the surface tension versus logarithm of concentration curve for poly(HCQNBMA)/NA shows only a slow decrease with increasing polymer concentration upon addition of various salts. The surface tension increases in the series KF>KCl>KBr>KI in a given polymer concentration. When the naphthalene label was introduced into the poly(HCQNBMA), the behavior of the solution properties of the poly(HCQNBMA)/NA could be clearly defined in terms of fluorescence analysis. The quenching efficiency of NaI or CH 3 NO 2 was reduced with increasing KCl concentration arising from compacted conformation of polymer chains. A model of the interaction between poly(HCQNBMA)/NA and surfactant or salt in aqueous solution is proposed.

Photophysical and solution properties of pyrene-labeled poly(3-dimethyl(methylmethacryloyl ethyl) ammonium propane sulfonate), poly(DMAPS/Py), were studied in terms of fluorescence emission measurement. The I E /I M was shown as a function of polymer concentration in deionized water. I E /I M value decreases with an increase in the salt concentration. The addition of surfactants to the aqueous solution of poly(DMAPS/Py) can either induce the mixed micelle of intra- polymer and its surrounding surfactants and/or mixed micelle of inter-polymers and their surrounding surfactants. Models of interactions between poly(DMAPS/Py) and surfactant or divalent salt in aqueous solution are proposed.

Different types of sulfobetaines and their corresponding cationic monomers and polymers derived from N,N-dialkylamino phenyl methacrylamide have been synthesized for this study. Comparing the chemical shifts in 1 H and 13 C NMR of the methylene groups in the cationic monomers and betaines reveal that the respective methylene groups are clearly distinguishable from each other. Results obtained from the intrinsic viscosity for zwitterionic poly(DEMAPhAPS) are opposite to that for the corresponding cationic poly(DEMMAPhAMS).

Interaction between naphthalene-labeled poly(hydrochloride quaternized 2-norbornene-5-methyleneamine), poly(HCQNBMA)/NA (luminophore), and quencher, emulsifier or coemulsifier in the aqueous or microemulsion media was studied by using steady-state fluorescence measurements. Fluorescence experiments were carried out with poly(HCQNBMA)/NA dissolved in the aqueous solutions of ionic and nonionic emulsifiers, emulsifier/n-hexane/water microemulsion (A) and emulsifier/n-hexane/1-pentanol/water microemulsion (B), respectively. The intensity of fluorescence emission of poly(HCQNBMA)/NA was much higher in the aqueous phase than in microemulsion. Furthermore, the aqueous solution of ionic emulsifier increased the monomer emission. The increase in the monomer emission can be ascribed to the shielding of the naphthalene (NA) groups by SDS micelles. This separates NA groups from each other, which depresses the deactivation of excited states. The strong decrease in monomer emission within the microemulsion media probably results from the elongated conformation structure of the polymer molecule, and higher conformation freedom of NA groups, which increases interaction between the probe and the quencher. The formation of nonfluorescence clusters is not ruled out. The quenching of NA emission by nitromethan (NM) is much stronger in microemulsion than in the aqueous phase, and the quenching is more pronounced for the low molecular weight 2-norbornene-5-methoxylnaphthalene (NBMNA) than for its polymer. The extent of penetration of reactants into the interfacial layer governs quenching of hydrophobic NA probe by hydrophilic quencher. Furthermore, the quenching events are connected with the thickness and density of the interfacial layer, as well as its charge. The addition of coemulsifier (1-pentanol) increases the total surface area of the microdroplets, the entry rate of reactants into the microdroplets, and the interaction of hydrophobic and hydrophilic reactants. The quenching events are more pronounced in the close packed o/w interfacial layer than in the loosely packed one. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 101–114, 2001

The aqueous solution properties of an ampholytic naphthalene-labelled acrylamide/N,N-dimethyl maleimido propyl ammonium propane sulphonate copolymer, poly(ADMMAPS)/NA, are examined in this study by measuring reduced and intrinsic viscosities. The intrinsic viscosity of the poly(ADMMAPS)/NA is related to the type and concentration of the salt added. This behaviour, resulting from the associations of the polymer chains, is in contrast with cationic and anionic polyelectrolytes. Smaller anions, such as F-, with a common cation (K+) are found to be the most difficult to be bound to the sulphonate group, indicating that a lower intrinsic viscosity of the poly(ADMMAPS)/NA would be found in aqueous KF solution. Smaller cations, such as Li+, with a common anion (Cl-) are found to be the most difficult to be bound to the quaternary ammonium group, indicating that a lower intrinsic viscosity of the poly(ADMMAPS)/NA would be found in LiCl salt aqueous solution. Because a naphthalene label was introduced into the polymer, the behaviour of the solution properties of the poly(ADMMAPS)/NA could be clearly defined in term of macroscopic and microscopic analysis. The models proposed in this study can account for the poly(ADMMAPS)/NA solution viscosities. © 1998 SCI.

The synthesis, rheological, and fluorescence properties of cationic watersoluble copolymer, naphthalene-labeled cationic poly(dimethyl sulfate quaternized acrylamide/N,N-dimethylaminopropylmaleimide copolymer), poly(DSQADMAPM)/ NA, are reported. When fluorescent hydrophobes (naphthyl group) are incorporated into the cationic copolymer, the photophysical response may effectively probe solution behavior on the microscopic level. The salt and pH responsiveness inherent to the cationic copolymer systems is a function of ionic group type. Experimental results indicate that I E /I M increases steadily with increases in polymer concentration and I E / I M values for a given polymer concentration are higher in salt. At low pH values, I E / I M is high and excimer emission increases as the quaternary amino groups (R 4 N + ) are screened out. Dynamic light scattering (QELS) measurements indicate that diffusion coefficients of the cationic copolymer increase and the hydrodynamic diameters decrease with increasing salt concentration. Viscosity studies reveal that the polymer coil shrinks as salt is added. In fluorescence quenching study, the reduction in the quenching efficiency of thallium (Tl + ) with salt addition can arise from enhanced compartmentalization of naphthalene labels as added electrolyte enhances intrapolymer micellization. The intrapolymer micelle is easily formed, indicating that the thallium ion has difficulty in reacting with bound naphthalenes located in the shrunk polymer coil. The cationic copolymer is depicted as an expanded polymer coil in deionized water because of intra-and interchain repulsions. Consequently, salt addition breaks down the repulsions and enhances intrapolymer micellization.

Two types of carboxybetaines and their corresponding cationic monomers and polymers are synthesized in this study. Comparing the chemical shifts of the methylene groups in the cationic monomers and carboxybetaines in both 1H- and 13C-NMR spectra reveal that the respective methylene groups are clearly distinguished from their chemical shifts in 1H- and 13C-NMR spectra. The solubilities, moisture regain properties, and solution properties of the poly(carboxybetaine)s and cationic polymers are investigated in relation to their molecular structures. Because the cationic polymers were ionized in an aqueous solution, the cationic polymers were more soluble than the poly(carboxybetaine). For the various functional groups of poly(carboxybetaine)s and cationic polymers, the order of tendency for moisture regain is COO > CONH. Results obtained from the reduced viscosity for cationic poly(TMMPAMS) are reversed from that for zwitterionic poly(DMAEAPL). © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3527–3536, 1997

The dilute solution properties of an anionic polyelectrolyte, poly(potassium-2-sulphopropylacrylate) (poly(SPA)) are studied by measurements of intrinsic viscosity, degree of binding, ionic strength and critical micelle concentration. The intrinsic viscosity of this polyelectrolyte is related to the type and concentration of the salt added. The intrinsic viscosity behaviour of an anionic polyelectrolyte resulting from the electrostatic repulsive force of the polymer chain is in contrast to that of a polyampholyte. The polyelectrolyte in high concentration of NaCl has a low degree of binding, indicating that the proton ion (H + ) is relatively difficult to bind to the sulphonate group (SO 3 - ) at the polymer end. An increase in ionic strength causes the pK a to decrease at the half-neutralization point. The monomer solutions exhibit a plot typical of those observed for detergents, with a break in the curve occurring at the critical micelle concentration. For the polymer solutions, no break in the equivalent conductance curve was found for the concentrations studied.