Interaction Of Functional Groups Research Articles

Preparation and properties of zein–rutin composite nanoparticle/corn starch films

Edible active films were prepared based on zein–rutin composite nanoparticles (RNs) and corn starch (CS). RNs (0, 0.5, 1, 2, 4, and 10%, w/w) were incorporated into CS films, to act as a natural antioxidant. Scanning electron microscopy and Fourier-transform infrared spectroscopy were used to examine the morphology and functional group interactions. The tensile strength and elongation at break increased from 1.19 to 2.42MPa, and from 42.10 to 78.84%, respectively, with increasing RN loading. The incorporation of RNs led to the formation of a net-like structure, which decreased the water vapor permeability and water solubility of the RN–CS film. The cumulative amount of rutin detected in vitro after 12h was 27.1–36.9% of the total amount of rutin. The RNs dispersed in the CS film provided controlled release of rutin. The antioxidant capacities of the films were greater than that of the pure CS film.

Synthesis and characterization of Torlon-based polyion complex for direct methanol and polymer electrolyte membrane fuel cells

An acid–base polyion complex membrane was synthesized by blending a polyamide-imide (Torlon) with sulfonated polyethersulfone (SPES), to make a sturdy proton-conducting electrolyte for portable fuel cells. The membrane was characterized by FTIR, XRD, TGA, SEM and UTM techniques. Chemical interactions between Torlon and SPES enabled the formation of ionic clusters that are useful for facilitating proton conduction and water sorption with prevention of fuel bypass. The complex exhibited high mechanical, thermal and oxidative stability with low methanol permeability (9.46 × 10−8 cm2/s). Sorption experiments showed the membrane to possess moderate affinity toward water with preferably low methanol uptake. Moreover, the blend membrane exhibited high proton conductivity (0.13 S/cm) at low humidity and high temperature conditions. To investigate the microstructure and transport behavior of the reported blend, molecular dynamics simulation based on COMPASS force field was performed. The diffusivity of hydronium ion obtained through simulation was used to calculate conductivity by Einstein equation. Proton conductivity obtained by simulation was validated by comparison with experimental data. Furthermore, the interaction of membrane functional groups with water and hydronium ion carrier was evaluated by radial distribution function. The study revealed the proposed complex to be an attractive, inexpensive alternative to state-of-the-art Nafion 117 membrane for fuel cell application.

Design, in silico and in vitro evaluation of curcumin analogues against Plasmodium falciparum

The polyphenolic compound curcumin has been reported for its antimalarial properties in various scientific studies. Plasmodium falciparum ATP6, the parasite orthologue of mammalian sarcoplasmic Ca2+ ATPase (SERCA) has been identified as a key molecular target of both artemisinin and curcumin. The work was thereby undertaken to study the anti-malarial properties of two different series of curcumin analogues based on their docking interactions with PfATP6 and correlating the results with their anti-malarial activity. The compounds were designed retaining similar functional groups as that of the parent curcumin nucleus while incorporating changes in the carbon chain length, unsaturated groups and the number of ketone groups. The compounds (1E, 4E)-1,5-bis(4-methylphenyl)penta-1,4-dien-3-one (CD-9), (1E, 4E)-1,5-bis(4-methoxyphenyl)penta-1,4-dien-3-one (CD-8) and (E)-1,3-bis(4-hydroxylphenyl)prop-2-en-1-one (CD-1) showed IC50 values of 1.642 μM, 1.764 μM and 2.59 μM in 3D7 strain and 3.039 μM, 7.40 μM and 11.3 μM in RKL-2 strain respectively. Detailed structure-activity relationship studies of the compounds showed that CD-9 and CD-8 had a common hydrophobic interaction with the residue Leu268 of the PfATP6 protein and has been postulated through our study to be the reason for their antimalarial activity as seen after corroborating the results with the in vitro study. The study provided valuable insight about the ligand-protein interaction of the various functional groups of curcumin and its analogues against the PfATP6 protein and their importance in imparting antimalarial action.

A novel in situ silver/hyaluronan bio-nanocomposite fabrics for wound and chronic ulcer dressing: In vitro and in vivo evaluations

In-situ formed hyaluronan/silver (HA/Ag) nanoparticles (NPs) were used to prepare composite fibers/fabrics for the first time. Different concentrations of silver nitrate (1, 2mg/100ml) were added at ambient temperature to sodium hyaluronate solution (40mg/ml), then the pH was increased to 8 by adding sodium hydroxide. The in-situ formed HA/Ag-NPs were used to prepare fibers/nonwoven fabrics by wet-dry-spinning technique (WDST). UV/vis spectroscopy, SEM, TEM, DLS, XPS, XRD and TGA were employed to characterize the structure and composition of the nanocomposite, surface morphology of fiber/fabrics, particle size of Ag-NPs, chemical interactions of Ag0 and HA functional groups, crystallinity and thermal stability of the wound dressing, respectively. The resultant HA/Ag-NPs1 and HA/Ag-NPs2 composite showed uniformly dispersed throughout HA fiber/fabrics (SEM), an excellent distribution of Ag-NPs with 25±2, nm size (TEM, DLS) and acceptable mechanical properties. The XRD analysis showed that the in-situ preparation of Ag-NPs increased the crystallinity of the resultant fabrics as well as the thermal stability. The antibacterial performance of medical HA/Ag-NPs fabrics was evaluated against gram negative bacteria E. coli K12, exhibiting significant bactericidal activity. The fibers did not show any cytotoxicity against human keratinocyte cell line (HaCaT). In-vivo animal tests indicated that the prepared wound dressing has strong healing efficacy (non-diabetics/diabetics rat model) compared to the plain HA fabrics and greatly accelerated the healing process. Based on our results, the new HA/Ag-NPs-2mg nonwoven wound dressing fabrics can be used in treating wounds and chronic ulcers as well as cell carrier in different biological research and tissue engineering.

A computational study on the role of noncovalent interactions in the stability of polymer/graphene nanocomposites.

Understanding the interaction between graphene and polymers is of essential interest when designing novel nanocomposites with reinforced mechanical and electrical properties. In this computational study, the interaction of pristine graphene (PG) and graphene oxide (GO) with a series of functional groups, representative of the functionalised buildings blocks occurring in different polymers, and attached to aliphatic and aromatic chains, is analyzed using dispersion-corrected semi-empirical methods (PM6-D3H4X) and density functional theory calculations with empirical dispersion corrections. Functional groups include alkyl, hydroxyl, aldehyde, carboxyl, amino and nitro groups, and the binding energies of these groups with graphene derivatives (PG and GO) are determined. Nitro- and carbonyl groups display stronger interactions in both aliphatic and aromatic chains. The importance of dispersion-type and non-covalent interactions (NCI) in general, which typically, double the interaction energies, is revealed. The results are interpreted in an extensive NCI analysis in order to characterize the different types of NCI, providing a better understanding of the nature of the interaction (π-π stacking, CH-π bonding, H-bonding and lone pair-π interaction) at stake. In order to highlight the influence of polymer structure/conformation on top of that of their functional groups, the binding of three polymers, polyethylene (PE), polystyrene (PS) and polyvinylidene fluoride (PVDF), on pristine graphene is also investigated. Our calculations indicate that, although all polymers exhibit evident attractive interactions with the graphene sheet, the overall interaction is strongly influenced by the specific polymer structure. Thus, three main conformations of PVDF (the so-called α, β and γ, ε conformations) are analyzed and we find that, although the α-conformer with a trans-gauche-trans-gauche (TGTG') conformation is the lowest energy conformer, the β-conformation of PVDF with the hydrogen atoms facing the graphene ("F-up") has the strongest interaction with the graphene surface among the polymers under consideration. Taken together, our computational approach sheds light on the character and importance of non-covalent graphene-polymer functional group interactions combined with the structural/conformational properties of the polymer, which are at stake in the design of novel nanocomposites with reinforced mechanical and electrical properties.

Indication of spatial variations in annual cycles of functional groups of planktonic ciliates to environmental change in marine ecosystems

The indication of spatial variations in annual cycles of functional groups of planktonic ciliates to environmental changes was studied in a bay, northern Yellow Sea. Samples were biweekly collected at five stations with different hydrographic conditions during a 1-year cycle. The second-stage-matrix-based multivariate approach was used to summarize the internal interactions of the ciliate functional groups among five stations during a 1-year period. The functional groups of the ciliates represented a clear spatial variation in annual cycle among five stations. Mantel analysis demonstrated that the spatial variation in annual cycles of the ciliate functional groups were significantly correlated with the changes nutrients (mainly soluble reactive phosphates and nitrates), alone or in combination with salinity among five stations. Based the results, it is suggested that the spatial variation in annual cycles of functional groups of planktonic ciliates may indicated the changes of hydrographic conditions.

Topological and biomass balance approaches to analyzing food webs of Bahía Magdalena, Baja California Sur, Mexico

In this paper, we used two methodological approaches to analyze the structure and function of a trophic web in the temperate coastal lagoon of Bahia Magdalena, Baja California Sur, Mexico, which represents the largest wetland ecosystem along the west coast of the Baja California peninsula. Ecosystem structure was studied using a topological approach, while ecosystem functioning was analyzed using a biomass balance model. Connectance values indicated a low number of functional group interactions, consistent with the range proposed for similar marine trophic webs. This pattern may reflect incorporation of a few functional groups clustered along the trophic web. Results would vary if the model included more functional groups or different levels of aggregation, since aggregation and diversity strongly influence the base of the food web. Topological results suggest that trophic web structure depends primarily on lower and intermediate trophic level organisms like macrobenthic invertebrates, penaeid shrimp and marine turtles. Balance biomass model results suggest that trophic groups positioned on the first level most strongly support Bahia Magdalena trophic web functioning. In particular, the pelagic red crab (Pleurocondes planipes) transfers energy between basal and upper levels of the food web (a wasp-waist energy control). When compared to ecosystems at different latitudes, the results indicate that the Bahia Magdalena ecosystem is still in a developmental phase, wherein trophic web functioning depends largely on the balance between energy flows originating from primary producers and those originating from detrital pathways. While these results are preliminary, they demonstrate the potential of combined topological and biomass approaches in analyzing highly organized ecosystems. The combined approach can make both theoretical and empirical predictions about the functional response of real systems to structural changes, thus enhancing evidence-based methods for ecosystem management.

Trends for isolated amino acids and dipeptides: Conformation, divalent ion binding, and remarkable similarity of binding to calcium and lead.

We derive structural and binding energy trends for twenty amino acids, their dipeptides, and their interactions with the divalent cations Ca2+, Ba2+, Sr2+, Cd2+, Pb2+, and Hg2+. The underlying data set consists of more than 45,000 first-principles predicted conformers with relative energies up to ~4 eV (~400 kJ/mol). We show that only very few distinct backbone structures of isolated amino acids and their dipeptides emerge as lowest-energy conformers. The isolated amino acids predominantly adopt structures that involve an acidic proton shared between the carboxy and amino function. Dipeptides adopt one of two intramolecular-hydrogen bonded conformations C5 or . Upon complexation with a divalent cation, the accessible conformational space shrinks and intramolecular hydrogen bonding is prevented due to strong electrostatic interaction of backbone and side chain functional groups with cations. Clear correlations emerge from the binding energies of the six divalent ions with amino acids and dipeptides. Cd2+ and Hg2+ show the largest binding energies–a potential correlation with their known high acute toxicities. Ca2+ and Pb2+ reveal almost identical binding energies across the entire series of amino acids and dipeptides. This observation validates past indications that ion-mimicry of calcium and lead should play an important role in a toxicological context.

Deciphering the structure of the West Greenland marine food web using stable isotopes (δ13C, δ15N)

The Arctic is facing major environmental changes impacting marine biodiversity and ecosystem functioning. One way of assessing the responses of an ecosystem to these changes is to quantitatively study food web dynamics. Here, we used stable isotope (δ15N and δ13C) analyses of 39 Arctic marine species to investigate trophic relationships and isotopic niches of the West Greenland food web in 2000–2004. The lowest δ15N values were found for suspension feeding blue mussel (Mytilus edulis; 6.1 ‰) and the highest for polar bear (Ursus maritimus; 20.2 ‰). For δ13C, copepods (Calanus spp.) had the lowest values (−20.4 ‰) and snow crab (Chionoecetes opilio) the highest values (−15.8 ‰). Our results show that the three trophic enrichment factor (TEF) approaches used to quantify species trophic positions (fixed TEF of 3.8 and 3.4 ‰ or scaled TEF) did not generally affect trophic modelling and provided similar conclusions. Overall, the findings in this study are in good agreement with previous investigations of other Arctic marine ecosystems. Interestingly, we found little overlap of core isotopic niches used by the four investigated functional groups (mammals, seabirds, fish and invertebrates), except for seabirds and fish where an overlap of 24 % was found. These results provide new insights into species and functional group interactions, as well as into the food web structure and ecosystem functioning of an important Arctic region that can be used as a template to guide future modelling of carbon, energy and contaminant flow in the region.

Novel ternary blends of natural rubber/linear low-density polyethylene/thermoplastic starch: influence of epoxide level of epoxidized natural rubber on blend properties

Novel degradable materials based on ternary blends of natural rubber (NR)/linear low-density polyethylene (LLDPE)/thermoplastic starch (TPS) were prepared via simple blending technique using three different types of natural rubber (i.e., unmodified natural rubber (RSS#3) and ENR with 25 and 50 mol% epoxide). The evolution of co-continuous phase morphology was first clarified for 50/50: NR/LLDPE blend. Then, 10 wt% of TPS was added to form 50/40/10: NR/LLDPE/TPS ternary blend, where TPS was the particulate dispersed phase in the NR/LLDPE matrix. The smallest TPS particles were observed in the ENR-50/LLDPE blend. This might be attributed to the chemical interactions of polar functional groups in ENR and TPS that enhanced their interfacial adhesion. We found that ternary blend of ENR-50/LLDPE/TPS exhibited higher 100 % modulus, tensile strength, hardness, storage modulus, complex viscosity and thermal properties compared with those of ENR-25/LLDPE/TPS and RSS#3/LLDPE/TPS ternary blends. Furthermore, lower melting temperature (T m) and heat of crystallization of LLDPE (∆H) were observed in ternary blend of ENR-50/LLDPE/TPS compared to the other ternary blends. Also, neat TPS exhibited the fastest biodegradation by weight loss during burial in soil for 2 or 6 months, while the ternary blends of NR/LLDPE/TPS exhibited higher weight loss compared to the neat NR and LLDPE. The lower weight loss of the ternary blends with ENR was likely due to the stronger chemical interfacial interactions. This proved that the blend with ENR had lower biodegradability than the blend with unmodified NR.

Thermal behavior and functional group interaction of lipids extracted from the stratum corneum

Attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) is a powerful tool for evaluating the functional group interaction of intercellular lipids in the stratum corneum. However, as the large amide I and amide II absorption bands are mainly derived from keratin, which constitutes about 90% of the stratum corneum, it is difficult to investigate the amide bonding interactions of intercellular lipids. In this study, we used extracted lipids from the stratum corneum to investigate the amide bonding derived from lipid interaction. Synchrotron X-ray diffraction studies showed that the extracted lipids formed hexagonal and orthorhombic structures, which play a key role in skin barrier function, as well as high-temperature hexagonal structures. Moreover, in ATR-FTIR measurements, the thermal profiles of stratum corneum lipids and extracted lipids showed similar behavior. The amide absorptions increased with increasing temperature, similar to the observations for the formation of high-temperature hexagonal structures by synchrotron X-ray diffraction. Furthermore, these characteristic changes were disturbed by l-menthol, which fluidizes the polar and hydrophobic regions of intercellular lipids in the stratum corneum. The extracted lipids were useful as an appropriate model of stratum corneum lipid organization for investigation of amide bonding interactions in stratum corneum lipids without interference from keratin.

Development of antimicrobial and scar preventive chitosan hydrogel wound dressings

Antimicrobial and scar preventive wound dressings were developed by coating a blend of chitosan (CS), polyethylene glycol (PEG) and polyvinyl pyrolidone (PVP) on the cotton fabric and subsequent freeze drying. The miscibility of blend systems and functional group interaction were investigated by attenuated total reflectance-infra red spectroscopy. The scanning electron microscopy of the coated fabric revealed porous structure. The porosity of the material was 54–70% and the pore size was in the range of 75-120μm depending on the blend composition. The air permeability diminished as the PVP content increased. The water vapour transmission rate was in the range of 2000–3500g/m2day which may offer to be proper material for the wound dressing with moderate exudate absorption. Tetracycline hydrochloride was used as model drug within the hydrogel matrix. The cumulative release of drug was found to be ∼80% of the total loading after ∼48h. The drug loaded dressings showed good antimicrobial nature against both gram positive and gram negative bacteria. In vivo wound healing and tissue compatibility studies were carried out over a period of 21 days on full-thickness skin wounds created on male Wistar rats. Fast healing was observed in drug loaded dressing treated wounds with minimum scarring, as compared to the other groups. These results suggest that drug loaded dressing could provide scar preventive wound healing.

Enhanced functional properties of chitosan films cross-linked by biosourced dicarboxylic acids

Chitosan-based films were developed using different biosourced dicarboxylic acid solutions (succinic acid, adipic acid, suberic acid and sebacic acid). The effect of incorporating these nontoxic solutions on water vapor barrier, tensile and antimicrobial properties of chitosan films was evaluated. Fourier Transform Infrared (FTIR) and cross polarization magic angle spinning (CP/MAS) nuclear magnetic resonance (NMR) analyses were also performed to investigate functional groups interactions between chitosan and dicarboxylic acids. Acetic acid-chitosan films showed significantly higher water vapor permeability (WVP) and lower tensile strength (TS) and elongation at break (%E) than dicarboxylic acid-prepared films (p < 0.05). Using either adipic acid or suberic acid solutions to fabricate chitosan films reduced WVP by 85% and enhanced TS by 21 to 27% and %E by more than 60% when compared with the acetic acid-prepared films. Chitosan films modified with either adipic acid or suberic acid exhibited antimicrobial activity against all tested microorganisms.

Molecular Probing of the HPV-16 E6 Protein Alpha Helix Binding Groove with Small Molecule Inhibitors.

The human papillomavirus (HPV) HPV E6 protein has emerged as a central oncoprotein in HPV-associated cancers in which sustained expression is required for tumor progression. A majority of the E6 protein interactions within the human proteome use an alpha-helix groove interface for binding. The UBE3A/E6AP HECT domain ubiquitin ligase binds E6 at this helix-groove interface. This enables formation of a trimeric complex with p53, resulting in destruction of this tumor suppressor. While recent x-ray crystal structures are useful, examples of small molecule probes that can modulate protein interactions at this interface are limited. To develop insights useful for potential structure-based design of ligands for HPV E6, a series of 2,6-disubstituted benzopyranones were prepared and tested as competitive antagonists of E6-E6AP helix-groove interactions. These small molecule probes were used in both binding and functional assays to evaluate recognition features of the E6 protein. Evidence for an ionic functional group interaction within the helix groove was implicated by the structure-activity among the highest affinity ligands. The molecular topographies of these protein-ligand interactions were evaluated by comparing the binding and activities of single amino acid E6 mutants with the results of molecular dynamic simulations. A group of arginine residues that form a rim-cap over the E6 helix groove offer compensatory roles in binding and recognition of the small molecule probes. The flexibility and impact on the overall helix-groove shape dictated by these residues offer new insights for structure-based targeting of HPV E6.

Functional Anodic and Cathodic Transition of Graphene Oxide using Lead Electrodes and Its Electrochemistry

The transition in the composition, electrical and fracture properties of graphene oxide paper (GO) in at the anode (aGO) and cathode (cGO) of lead /sulphuric acid boundary have been studied. Higher thermal stability and lower weight loss of aGO (34wt% at 800 °C) with XRD peak at 2ϴ = 10.5° showed the reduction of the ordinary GO paper (95wt% at 800 °C). The fractographs from the SEM showed that the cGO failed by ductile rupture of a higher degree than the ordinary GO paper, while that of the aGO was brittle cleavage. UV-Vis, Fourier Transform Infrared and X-ray Photoelectron Spectroscopies showed the changes in functional groups, via the interaction of graphene oxide functional groups with protons, adsorbed oxygen containing ions. Graphene/lead oxide based composite was achieved by covalent interactions. Non-covalent complexation of metal ions with slight reduction gave rise to stronger graphene oxide paper at the cathode. The electrical conductivity of aGO are 1.61 x 106 S/m and those of the cGO are 4.27 X 105 S/m. This foremost work is useful for further study of graphene oxide electrochemical reduction and metallic oxide functionalization for electrode materials in advanced lead-carbon batteries.

Characterization of copper (II) biosorption by brown algae Durvillaea antarctica dead biomass

In this study we analyze the Cu(II) biosorption characteristics of the dead biomass of the Chilean brown macroalgae Durvillaea antarctica as a function of initial metal ion concentration and pH. We determined an equilibrium time of 120 min and a maximum biosorption performance at pH 5.0. The isotherms data at optimum pH best fitted with the Dubinin–Radushkevish model, showing a maximum capacity for Cu(II) biosorption of 1.44 mmol g−1. A quantitative analysis by potentiometric titrations was performed to determine different acid–base properties of the biomass surface and a FTIR analysis was performed to identify the key functional groups present on the biomass. We found characteristic peaks corresponding mainly to amine, carboxylate, hydroxyl and sulphonate moieties. A time course FTIR analysis of interaction between the biomass and Cu(II) in aqueous solution was performed to estimate sequential steps of functional groups interactions, and a SEM analysis was performed to observe the textural properties of D. antarctica biomass surface. The value of the total cation exchange capacity supports an ion exchange mechanism for the adsorption of Cu(II) by the biomass, characterized as an physisorption phenomena in a multilayer heterogeneous system.

Enhancing the pre-polymerization coordination of 1-vinylimidazole

Recent experimental investigations have found that the rate and conversion of the photopolymerization of 1-vinylimidazole (VIm) can be significantly accelerated with the addition of lithium bistriflimide (LiTf2N). However, the underlying molecular-level interactions responsible for this phenomenon are unclear. The two components, VIm and LiTf2N, are miscible over a wide range of concentrations and form liquid phases at ambient temperature, and if the fundamental behavior of this mixture can be clearly quantified, there are significant opportunities for tuning the polymerization dynamics, polymer structure, and properties. In this work, molecular dynamics (MD) simulations are used to model the underlying pre-polymerization structure of VIm+LiTf2N mixtures at several different concentrations. It is found that the Li+ enhances the site–site interactions of key functional groups involved in the polymerization, and this is suggested to play a major role in the experimentally-observed enhancement of the polymerization behavior.

Synthesis of amide-functionalized cellulose esters by olefin cross-metathesis

Cellulose esters with amide functionalities were synthesized by cross-metathesis (CM) reaction of terminally olefinic esters with different acrylamides, catalyzed by Hoveyda–Grubbs 2nd generation catalyst. Chelation by amides of the catalyst ruthenium center caused low conversions using conventional solvents. The effects of both solvent and structure of acrylamide on reaction conversion were investigated. While the inherent tendency of acrylamides to chelate Ru is governed by the acrylamide N-substituents, employing acetic acid as a solvent significantly improved the conversion of certain acrylamides, from 50% to up to 99%. Homogeneous hydrogenation using p-toluenesulfonyl hydrazide successfully eliminated the α,β-unsaturation of the CM products to give stable amide-functionalized cellulose esters. The amide-functionalized product showed higher Tg than its starting terminally olefinic counterpart, which may have resulted from strong hydrogen bonding interactions of the amide functional groups.

Characteristic and mechanism of Th4+ sorption from nitric acid solutions by rice and wheat bran

Abstract In line with our previously conducted researches, various instrumental methods were applied to evaluate the adsorption features and mechanism of Th4+ from highly acidic solution (4 M HNO3) by rice and wheat bran. Although the results of cation exchange confirmed the existence of ion-exchange interaction in Th4+ adsorption, it had a trivial contribution in the biosorption process. The presence of Th4+ ions on the biomass surface was obviously revealed in SEM images and EDS elemental analysis. Moreover, the linkage of C=O, O–H and N–H functional groups on the biomass surface with Th4+ ions was clearly represented in the ATR-FTIR spectroscopic analysis. Additionally, desorption studies indicated that ammonium oxalate (&gt;81.3%) and ammonium carbonate (&gt;75.4%) were effective in desorbing Th4+ from the biomass surface due to strong interactions of hard functional groups of C=O with Th4+. The overall observations unfold the fact that electrostatic complexation mechanism is dominant between biomass and Th4+ ions.

INFLUENCE OF MODIFIED NATURAL RUBBER ON PROPERTIES OF NATURAL RUBBER–CARBON NANOTUBE COMPOSITES

ABSTRACT Carbon nanotube (CNT)–filled natural rubber (NR) composites were prepared by using an internal mixer and a two-roll mill. Various types of NR, including unmodified NR, epoxidized NR (ENR), and maleated NR (MNR), were used. The chemical reactions between rubber molecules and functional groups on the CNT surface were characterized by attenuated total reflection Fourier transform infrared spectroscopy. Cure characteristics, tensile properties, relaxation behavior, and electrical conductivity of the various gum rubbers and the CNT-filled rubber composites were investigated. It was found that the addition of CNTs significantly affected the composite properties. This is due not only to the excellent properties of the CNT itself but also to the physical and chemical interactions between modified rubber molecules and CNT surfaces. On comparison between the three types of NR, it was observed that the ENR-CNT composite showed the highest values of delta torque, tensile strength, and initial relaxation modulus. This confirms the homogeneous distribution of CNT particles in the ENR matrix, which in turn resulted from enhanced interactions of functional groups on CNT surfaces and epoxide groups in ENR molecules. Furthermore, electrical conductivity as a function of CNT content was examined to estimate the electrical percolation threshold value and to determine the state of dispersion of CNTs.