Using nonequilibrium molecular dynamic simulations, the thermal conductivity of a set of Si phono... more Using nonequilibrium molecular dynamic simulations, the thermal conductivity of a set of Si phononic metamaterial nanowires with a twinning superlattice structure has been investigated. We first show that this latter structural modulation can yield 65% thermal-conductivity reduction compared to the straight wire case at room temperature. Second, a purely geometry-induced minimal thermal conductivity of the phononic metamaterial is observed at a specific period depending on the nanowire diameter. Mode analysis reveals that the the minimal thermal conductivity arises due to the disappearance of favored atom polarization directions. The current thermalconductivity reduction mechanism can collaborate with the other known reduction mechanisms, such as the one related to coating, to further reduce thermal conductivity of the metamaterial. Current studies reveal that twinning superlattice nanowires could serve as a promising candidate for efficient thermoelectric conversion benefitting from the large suppression in thermal transport and without deterioration of electron-transport properties when the surface atoms are passivated.
Quartz crystal microbalance dissipation (QCM-D) was used to monitor the layer by layer (LBL) self... more Quartz crystal microbalance dissipation (QCM-D) was used to monitor the layer by layer (LBL) selfassemble process of decyl bis phosphonate (DBP) and Collagen on titanium. The mass and viscoelastic properties of self-assembled layers were obtained using QCM-D. The stability of DBP and Collagen layer on titanium was tested to be very good. Osteoblasts cell culture was performed on LBL modified samples and that after BSA adsorption. The morphology of cells was observed by a scanning electron microscope (SEM). The total metabolic activity and differentiation of osteoblasts were evaluated by a metabolic assay and alkaline phosphatase (ALP) activity, respectively. These tests showed that osteoblasts have better activity, proliferation, and differentiation on Collagen terminated samples and BSA adsorbed samples.
Titanium and its alloys have been applied in orthopedics due to their biocompatibility, mechanica... more Titanium and its alloys have been applied in orthopedics due to their biocompatibility, mechanical, and physical properties. Here we use decyl bis phosphonate (DBP) and collagen I to modify Ti-6Al-4V through layerby-layer technique in order to improve its bioactivity. The abilities of bovine serum albumin (BSA) adsorption and biomimetic mineralization of different sample surfaces were studied. X-ray photoelectron spectroscopy (XPS) and water contact angle data showed that DBP and collagen I were assembled on substrates successfully. The absorbance of BSA solution acquired from ultraviolet spectrophotometer (UV) indicated that samples of Ti-6Al-4V/DBP/Collagen and Ti-6Al-4V/DBP/Collagen/DBP adsorbed BSA most, followed by Ti-6Al-4V/DBP and Ti-6Al-4V. Scanning electron microscope (SEM) photos and X-ray diffraction (XRD) data showed that sample of Ti-6Al-4V/ DBP/Collagen had better bioactivity in inducing HA formation than other samples tested in this investigation.
The carbon nanotubes' resilience to mechanical deformation is a potentially important feature for... more The carbon nanotubes' resilience to mechanical deformation is a potentially important feature for imparting tunable properties at the nanoscale. Using nonequilibrium molecular dynamics and empirical interatomic potentials, we examine the thermal conductivity variations with bending in the thermal transport regime where both ballistic and diffusive effects coexist. These simulations are enabled by the realistic atomic-scale descriptions of uniformly curved and buckled nanotube morphologies obtained by imposing objective boundary conditions. We uncover a contrasting behavior. At shorter lengths, the phonon propagation is affected significantly by the occurrence of localized structural buckling. As the nanotube length becomes comparable with the phonon mean free path, heat transport becomes insensitive to the buckling deformations. Our result settles the controversy around the differences between the current experimental and molecular-dynamics measurements of the thermal transport in bent nanotubes.
In the framework of the European Union FP7 project EuCARD, two composite insulation systems made ... more In the framework of the European Union FP7 project EuCARD, two composite insulation systems made of cyanate ester epoxy mix and tri-functional epoxy (TGPAP-DETDA) with S-glass fiber have been thermally tested as possible candidates to be the electrical insulation of 13 T Nb 3 Sn high field magnets under development for this program. Since it is expected to be operated in pressurized superfluid helium at 1.9 K and 1 atm, the thermal conductivity and the Kapitza resistance are the most important input parameters for the thermal design of this type of magnet and have been determined in this study. For determining these thermal properties, three sheets of each material with different thicknesses varying from 245 to 598 lm have been tested in steady-state condition in the temperature range of 1.6-2.0 K. The thermal conductivity for the tri-functional epoxy (TGPAP-DETDA) epoxy resin insulation is found to be k = [(34.2 ± 5.5)ÁT À (16.4 ± 8.2)] Â 10 À3 Wm À1 K À1 and for the cyanate ester epoxy k = [(26.8 ± 4.8)ÁT À (9.6 ± 5.2)] Â 10 À3 Wm À1 K À1 . For the Kapitza resistance, R k , the best curve fitting the experimental data is described by R k = (3057 ± 593) Â 10 À6 ÁT (À1.79 ± 0.34) m 2 KW À1 for the TGPAP-DETDA insulation and R k = (4114 ± 971) Â 10 À6 ÁT (À1.73 ± 0.41) m 2 KW À1 for the cyanate ester epoxy insulation. Our results are compared with other epoxy based composite electrical insulation found in the literature.
ABSTRACT The influence of vacancy defects on the electronic and phonon properties of graphene is ... more ABSTRACT The influence of vacancy defects on the electronic and phonon properties of graphene is studied with the models based on a unit cell of 180 carbon atoms and of 1, 2, 3, 6, and 24 vacancies. Ordered, with one defect per unit cell, and non-ordered (randomly arranged) vacancies are calculated with firstprinciple and molecular dynamics methods. Randomly oriented vacancies lead to a creation of characteristic V1(5-9) defects and the amorphization of graphene with different rings. Electronic and phonon densities of states are analyzed. The switching of the electrical conductivity from metal to semiconductor type is observed when increasing the defect sizes from a single vacancy to large clusters. The characteristic phonon modes are found in all these cases for their future experimental identification. Novel types of devices are proposed via doping of defective graphene.
We report the layer-number dependence of the averaged interlayer thermal resistances (R int ) of ... more We report the layer-number dependence of the averaged interlayer thermal resistances (R int ) of the suspended and supported few-layer graphene (FLG), simulated by equilibrium molecular dynamics (EMD). The existence of a silicon dioxide substrate significantly decreases the R int of FLG at low layer number. We use the model of long-wavelength dynamics of a nanolayer adsorbed on a deformable crystal [Kosevich and Syrkin, Phys. Lett. A 135, 298 (1989)] to explain the appearance of the substrate-induced gaps in the FLG dispersion curves and phonon radiation into the deformable substrate from these gap modes. The enhanced thermal conductance in the cross-plane direction is ascribed to the phonon radiation from FLG into the deformable substrate, which partially transfers the flow of phonon energy in FLG from the in-plane to the cross-plane direction and to the substrate. To confirm this, we calculate the cross-plane thermal resistance of three-layer graphene supported by an effective SiO 2 substrate in which atomic masses are increased by a factor of 1000. This makes the substrate almost immovable and suppresses phonon radiation from the supported FLG by complete phonon reflection at the interface. The cross-plane thermal resistance of three-layer graphene supported on such a substrate is found to be the same as its suspended counterpart.
Inter-plane thermal resistance in 5-layer graphene is calculated from equilibrium molecular dynam... more Inter-plane thermal resistance in 5-layer graphene is calculated from equilibrium molecular dynamics (EMD) by calculating the autocorrelation function of temperature difference. Our simulated inter-plane resistance for 5-layer graphene is 4.83 × 10 -9 m 2 K/W. This data is in the same order of magnitude with the reported values from NEMD simulations and Debye model calculations, and the possible reasons for the slight differences are discussed in details. The inter-plane resistance is not dependent on temperature, according to the results of the EMD simulation. Phonon density of states (DOSs) were plotted to better understand the mechanism behind the obtained values. These results provide a better insight in the heat transfer across a few layer graphene and yield useful information on the design of graphene based thermal materials.
Effect of first row transition metals on the conductivity of semiconducting single-walled carbon ... more Effect of first row transition metals on the conductivity of semiconducting single-walled carbon nanotube networks Appl. Phys. Lett. 100, 223111 Lateral spin transport through bulk silicon Appl. Phys. Lett. 100, 162408 Localization effects in the tunnel barriers of phosphorus-doped silicon quantum dots AIP Advances 2, 022114 Room-temperature anomalous Hall effect in amorphous Si-based magnetic semiconductor Appl. Phys. Lett. 100, 092404 Spin-dependent recombination in Czochralski silicon containing oxide precipitates
The thermal conductivity of diameter and polytype modulated SiC nanowires is predicted using none... more The thermal conductivity of diameter and polytype modulated SiC nanowires is predicted using nonequilibrium molecular dynamics. For the polytype modulated nanowires, the two main SiC polytypes, zinc blende (3C) and wurtzite (2H ) were considered. We show that the thermal conductivity of the diameter modulated nanowires may be even smaller than that of the constant diameter nanowire with the small section. This remarkable reduction in thermal conduction is attributed to a significant thermal boundary resistance displayed by the constriction, as measured by independent molecular-dynamics simulations. The constriction resistance is related to the confinement of low-frequency modes, as shown by vibrational density-of-states calculations. We used Monte Carlo simulations to conclude that the value of the constriction resistance may be explained by the specular reflections of this class of modes on the surface surrounding the constriction.
Journal of Industrial and Engineering Chemistry, 2014
ABSTRACT Four novel multiple-acidic ionic liquids based on triethanolamine (TEA) were prepared an... more ABSTRACT Four novel multiple-acidic ionic liquids based on triethanolamine (TEA) were prepared and used as efficient catalysts to synthesize bis-indolylmethanes at room temperature without any organic solvent. [TEOA][HSO4] showed the best catalytic performance. The optimal amount of catalyst was 10 mol%. Various aldehydes/ketones reacted with indole/substituted indole smoothly and afforded to corresponding products in 70–99% yields within minutes. Additionally, the ionic liquid could be reused up to five times with only a slight decrease in catalytic activity. Finally, a possible reaction mechanism was given. Techniques of acidity test and NMR were introduced to verify the proposed mechanism.
ABSTRACT Knoevenagel condensation of aromatic aldehydes with active methylene compounds such as m... more ABSTRACT Knoevenagel condensation of aromatic aldehydes with active methylene compounds such as malononitrile, ethylcyanoacetate, benzimidazol-2-acetonitrile and benzothiazole-2-acetonitrile proceeded very smoothly, catalyzed by nano-Fe3O4 encapsulated-silica particles supported primary amine. Both reaction time and yield are satisfying. The advantages of this catalyst are ease of preparation, non-toxicity, low cost, ease of handling and recyclability.
ABSTRACT Abstract Ionic tagged propyl amine immobilized on magnetic nanoparticles (MNPs) was synt... more ABSTRACT Abstract Ionic tagged propyl amine immobilized on magnetic nanoparticles (MNPs) was synthesized and fully characterized. The novel catalyst (MNPs@PA-IL) was applied in phospha-Michael addition and gave the desired β-phosphonomalonates in good yields. The MNPs supported catalyst with ionic tag could be readily recovered from the reaction mixture using an external magnet. Compared with ionic-free counterpart (MNPs@PA), MNPs@PA-IL present better catalytic activity. The proposed mechanism regarding the MNPs@PA-IL catalyzed phospha-Michael reaction was also discussed. Graphical Abstract
... Although the dynamical properties of the OCP (dynamical structure factor, transport ... The e... more ... Although the dynamical properties of the OCP (dynamical structure factor, transport ... The effectiveinteraction between two ions (i, j) of distant of will be denoted and we have where denotes a vector of the reciprocal lattice ([openface Z] set of positive and negative integers). ...
Abstract This study describes the synthesis of Ag nanoparticles using DNA templates with polymorp... more Abstract This study describes the synthesis of Ag nanoparticles using DNA templates with polymorphic structures including the G-quadruplex, the I-motif, and the Duplex and their application for the catalytic reduction of 4-nitrophenol by NaBH4. Interactions between Ag+ and polymorphic DNA were studied through circular dichroism, polyacrylamide gels, and UV spectroscopy. Ag nanoparticles with narrow size distributions were prepared through the reduction of Ag+ by NaBH4 under different DNA templates and Ag+/base ratios. These DNA-templated Ag nanoparticles demonstrated excellent catalytic performance in the reduction reaction of 4-nitrophenol. The rate constants depended on the structure of DNA template, with the decreasing order: I-motif-Ag > G-quadruplex-Ag > Duplex-Ag. The results obtained here suggest a promising pathway to adjust physical–chemical properties of metal nanoparticles through the template of polymorphic DNA. Graphical Abstract
Using nonequilibrium molecular dynamic simulations, the thermal conductivity of a set of Si phono... more Using nonequilibrium molecular dynamic simulations, the thermal conductivity of a set of Si phononic metamaterial nanowires with a twinning superlattice structure has been investigated. We first show that this latter structural modulation can yield 65% thermal-conductivity reduction compared to the straight wire case at room temperature. Second, a purely geometry-induced minimal thermal conductivity of the phononic metamaterial is observed at a specific period depending on the nanowire diameter. Mode analysis reveals that the the minimal thermal conductivity arises due to the disappearance of favored atom polarization directions. The current thermalconductivity reduction mechanism can collaborate with the other known reduction mechanisms, such as the one related to coating, to further reduce thermal conductivity of the metamaterial. Current studies reveal that twinning superlattice nanowires could serve as a promising candidate for efficient thermoelectric conversion benefitting from the large suppression in thermal transport and without deterioration of electron-transport properties when the surface atoms are passivated.
Quartz crystal microbalance dissipation (QCM-D) was used to monitor the layer by layer (LBL) self... more Quartz crystal microbalance dissipation (QCM-D) was used to monitor the layer by layer (LBL) selfassemble process of decyl bis phosphonate (DBP) and Collagen on titanium. The mass and viscoelastic properties of self-assembled layers were obtained using QCM-D. The stability of DBP and Collagen layer on titanium was tested to be very good. Osteoblasts cell culture was performed on LBL modified samples and that after BSA adsorption. The morphology of cells was observed by a scanning electron microscope (SEM). The total metabolic activity and differentiation of osteoblasts were evaluated by a metabolic assay and alkaline phosphatase (ALP) activity, respectively. These tests showed that osteoblasts have better activity, proliferation, and differentiation on Collagen terminated samples and BSA adsorbed samples.
Titanium and its alloys have been applied in orthopedics due to their biocompatibility, mechanica... more Titanium and its alloys have been applied in orthopedics due to their biocompatibility, mechanical, and physical properties. Here we use decyl bis phosphonate (DBP) and collagen I to modify Ti-6Al-4V through layerby-layer technique in order to improve its bioactivity. The abilities of bovine serum albumin (BSA) adsorption and biomimetic mineralization of different sample surfaces were studied. X-ray photoelectron spectroscopy (XPS) and water contact angle data showed that DBP and collagen I were assembled on substrates successfully. The absorbance of BSA solution acquired from ultraviolet spectrophotometer (UV) indicated that samples of Ti-6Al-4V/DBP/Collagen and Ti-6Al-4V/DBP/Collagen/DBP adsorbed BSA most, followed by Ti-6Al-4V/DBP and Ti-6Al-4V. Scanning electron microscope (SEM) photos and X-ray diffraction (XRD) data showed that sample of Ti-6Al-4V/ DBP/Collagen had better bioactivity in inducing HA formation than other samples tested in this investigation.
The carbon nanotubes' resilience to mechanical deformation is a potentially important feature for... more The carbon nanotubes' resilience to mechanical deformation is a potentially important feature for imparting tunable properties at the nanoscale. Using nonequilibrium molecular dynamics and empirical interatomic potentials, we examine the thermal conductivity variations with bending in the thermal transport regime where both ballistic and diffusive effects coexist. These simulations are enabled by the realistic atomic-scale descriptions of uniformly curved and buckled nanotube morphologies obtained by imposing objective boundary conditions. We uncover a contrasting behavior. At shorter lengths, the phonon propagation is affected significantly by the occurrence of localized structural buckling. As the nanotube length becomes comparable with the phonon mean free path, heat transport becomes insensitive to the buckling deformations. Our result settles the controversy around the differences between the current experimental and molecular-dynamics measurements of the thermal transport in bent nanotubes.
In the framework of the European Union FP7 project EuCARD, two composite insulation systems made ... more In the framework of the European Union FP7 project EuCARD, two composite insulation systems made of cyanate ester epoxy mix and tri-functional epoxy (TGPAP-DETDA) with S-glass fiber have been thermally tested as possible candidates to be the electrical insulation of 13 T Nb 3 Sn high field magnets under development for this program. Since it is expected to be operated in pressurized superfluid helium at 1.9 K and 1 atm, the thermal conductivity and the Kapitza resistance are the most important input parameters for the thermal design of this type of magnet and have been determined in this study. For determining these thermal properties, three sheets of each material with different thicknesses varying from 245 to 598 lm have been tested in steady-state condition in the temperature range of 1.6-2.0 K. The thermal conductivity for the tri-functional epoxy (TGPAP-DETDA) epoxy resin insulation is found to be k = [(34.2 ± 5.5)ÁT À (16.4 ± 8.2)] Â 10 À3 Wm À1 K À1 and for the cyanate ester epoxy k = [(26.8 ± 4.8)ÁT À (9.6 ± 5.2)] Â 10 À3 Wm À1 K À1 . For the Kapitza resistance, R k , the best curve fitting the experimental data is described by R k = (3057 ± 593) Â 10 À6 ÁT (À1.79 ± 0.34) m 2 KW À1 for the TGPAP-DETDA insulation and R k = (4114 ± 971) Â 10 À6 ÁT (À1.73 ± 0.41) m 2 KW À1 for the cyanate ester epoxy insulation. Our results are compared with other epoxy based composite electrical insulation found in the literature.
ABSTRACT The influence of vacancy defects on the electronic and phonon properties of graphene is ... more ABSTRACT The influence of vacancy defects on the electronic and phonon properties of graphene is studied with the models based on a unit cell of 180 carbon atoms and of 1, 2, 3, 6, and 24 vacancies. Ordered, with one defect per unit cell, and non-ordered (randomly arranged) vacancies are calculated with firstprinciple and molecular dynamics methods. Randomly oriented vacancies lead to a creation of characteristic V1(5-9) defects and the amorphization of graphene with different rings. Electronic and phonon densities of states are analyzed. The switching of the electrical conductivity from metal to semiconductor type is observed when increasing the defect sizes from a single vacancy to large clusters. The characteristic phonon modes are found in all these cases for their future experimental identification. Novel types of devices are proposed via doping of defective graphene.
We report the layer-number dependence of the averaged interlayer thermal resistances (R int ) of ... more We report the layer-number dependence of the averaged interlayer thermal resistances (R int ) of the suspended and supported few-layer graphene (FLG), simulated by equilibrium molecular dynamics (EMD). The existence of a silicon dioxide substrate significantly decreases the R int of FLG at low layer number. We use the model of long-wavelength dynamics of a nanolayer adsorbed on a deformable crystal [Kosevich and Syrkin, Phys. Lett. A 135, 298 (1989)] to explain the appearance of the substrate-induced gaps in the FLG dispersion curves and phonon radiation into the deformable substrate from these gap modes. The enhanced thermal conductance in the cross-plane direction is ascribed to the phonon radiation from FLG into the deformable substrate, which partially transfers the flow of phonon energy in FLG from the in-plane to the cross-plane direction and to the substrate. To confirm this, we calculate the cross-plane thermal resistance of three-layer graphene supported by an effective SiO 2 substrate in which atomic masses are increased by a factor of 1000. This makes the substrate almost immovable and suppresses phonon radiation from the supported FLG by complete phonon reflection at the interface. The cross-plane thermal resistance of three-layer graphene supported on such a substrate is found to be the same as its suspended counterpart.
Inter-plane thermal resistance in 5-layer graphene is calculated from equilibrium molecular dynam... more Inter-plane thermal resistance in 5-layer graphene is calculated from equilibrium molecular dynamics (EMD) by calculating the autocorrelation function of temperature difference. Our simulated inter-plane resistance for 5-layer graphene is 4.83 × 10 -9 m 2 K/W. This data is in the same order of magnitude with the reported values from NEMD simulations and Debye model calculations, and the possible reasons for the slight differences are discussed in details. The inter-plane resistance is not dependent on temperature, according to the results of the EMD simulation. Phonon density of states (DOSs) were plotted to better understand the mechanism behind the obtained values. These results provide a better insight in the heat transfer across a few layer graphene and yield useful information on the design of graphene based thermal materials.
Effect of first row transition metals on the conductivity of semiconducting single-walled carbon ... more Effect of first row transition metals on the conductivity of semiconducting single-walled carbon nanotube networks Appl. Phys. Lett. 100, 223111 Lateral spin transport through bulk silicon Appl. Phys. Lett. 100, 162408 Localization effects in the tunnel barriers of phosphorus-doped silicon quantum dots AIP Advances 2, 022114 Room-temperature anomalous Hall effect in amorphous Si-based magnetic semiconductor Appl. Phys. Lett. 100, 092404 Spin-dependent recombination in Czochralski silicon containing oxide precipitates
The thermal conductivity of diameter and polytype modulated SiC nanowires is predicted using none... more The thermal conductivity of diameter and polytype modulated SiC nanowires is predicted using nonequilibrium molecular dynamics. For the polytype modulated nanowires, the two main SiC polytypes, zinc blende (3C) and wurtzite (2H ) were considered. We show that the thermal conductivity of the diameter modulated nanowires may be even smaller than that of the constant diameter nanowire with the small section. This remarkable reduction in thermal conduction is attributed to a significant thermal boundary resistance displayed by the constriction, as measured by independent molecular-dynamics simulations. The constriction resistance is related to the confinement of low-frequency modes, as shown by vibrational density-of-states calculations. We used Monte Carlo simulations to conclude that the value of the constriction resistance may be explained by the specular reflections of this class of modes on the surface surrounding the constriction.
Journal of Industrial and Engineering Chemistry, 2014
ABSTRACT Four novel multiple-acidic ionic liquids based on triethanolamine (TEA) were prepared an... more ABSTRACT Four novel multiple-acidic ionic liquids based on triethanolamine (TEA) were prepared and used as efficient catalysts to synthesize bis-indolylmethanes at room temperature without any organic solvent. [TEOA][HSO4] showed the best catalytic performance. The optimal amount of catalyst was 10 mol%. Various aldehydes/ketones reacted with indole/substituted indole smoothly and afforded to corresponding products in 70–99% yields within minutes. Additionally, the ionic liquid could be reused up to five times with only a slight decrease in catalytic activity. Finally, a possible reaction mechanism was given. Techniques of acidity test and NMR were introduced to verify the proposed mechanism.
ABSTRACT Knoevenagel condensation of aromatic aldehydes with active methylene compounds such as m... more ABSTRACT Knoevenagel condensation of aromatic aldehydes with active methylene compounds such as malononitrile, ethylcyanoacetate, benzimidazol-2-acetonitrile and benzothiazole-2-acetonitrile proceeded very smoothly, catalyzed by nano-Fe3O4 encapsulated-silica particles supported primary amine. Both reaction time and yield are satisfying. The advantages of this catalyst are ease of preparation, non-toxicity, low cost, ease of handling and recyclability.
ABSTRACT Abstract Ionic tagged propyl amine immobilized on magnetic nanoparticles (MNPs) was synt... more ABSTRACT Abstract Ionic tagged propyl amine immobilized on magnetic nanoparticles (MNPs) was synthesized and fully characterized. The novel catalyst (MNPs@PA-IL) was applied in phospha-Michael addition and gave the desired β-phosphonomalonates in good yields. The MNPs supported catalyst with ionic tag could be readily recovered from the reaction mixture using an external magnet. Compared with ionic-free counterpart (MNPs@PA), MNPs@PA-IL present better catalytic activity. The proposed mechanism regarding the MNPs@PA-IL catalyzed phospha-Michael reaction was also discussed. Graphical Abstract
... Although the dynamical properties of the OCP (dynamical structure factor, transport ... The e... more ... Although the dynamical properties of the OCP (dynamical structure factor, transport ... The effectiveinteraction between two ions (i, j) of distant of will be denoted and we have where denotes a vector of the reciprocal lattice ([openface Z] set of positive and negative integers). ...
Abstract This study describes the synthesis of Ag nanoparticles using DNA templates with polymorp... more Abstract This study describes the synthesis of Ag nanoparticles using DNA templates with polymorphic structures including the G-quadruplex, the I-motif, and the Duplex and their application for the catalytic reduction of 4-nitrophenol by NaBH4. Interactions between Ag+ and polymorphic DNA were studied through circular dichroism, polyacrylamide gels, and UV spectroscopy. Ag nanoparticles with narrow size distributions were prepared through the reduction of Ag+ by NaBH4 under different DNA templates and Ag+/base ratios. These DNA-templated Ag nanoparticles demonstrated excellent catalytic performance in the reduction reaction of 4-nitrophenol. The rate constants depended on the structure of DNA template, with the decreasing order: I-motif-Ag > G-quadruplex-Ag > Duplex-Ag. The results obtained here suggest a promising pathway to adjust physical–chemical properties of metal nanoparticles through the template of polymorphic DNA. Graphical Abstract
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