Preparation and Characterization of Molecularly Imprinted Polymeric Nanoparticles for Atrial Natriuretic Peptide (ANP)

Natriuretic peptide receptor A (NPRA), the receptor for the cardiac hormone atrial natriuretic peptide (ANP), is expressed abundantly on cancer cells and disruption of ANP‐NPRA signaling inhibits tumor burden and metastasis. Since antagonists of NPRA signaling have not provided reproducible results, we reason that a synthetic neutralizing antibody to ANP, which has high selectivity and affinity for ANP, can be used to regulate ANP levels and attenuate NPRA signaling. In this study, we prepare molecularly imprinted polymeric nanoparticles (MIPNPs) for ANP using a short peptide of ANP as the template and determine their binding affinity and selectivity. The MIPNPs are prepared by precipitation polymerization using NH₂–SLRRSS–CONH₂, which is a short peptide from ANP, as a template, methacrylic acid and N‐isopropylacrylamide as functional monomers, and bis‐acrylamide as a crosslinker. The average diameters of the MIPNPs and of non‐imprinted nanoparticles (NIPNPs) in water are 215.8 ± 4.6 nm and 197.7 ± 3.1 nm respectively. The binding‐isotherm analysis shows that the MIPNPs have a much‐higher binding affinity for the template peptide and ANP than the NIPNPs. Scatchard analysis gives an equilibrium dissociation constant, K_d, of 7.3 × 10^?6 M with a binding capacity of 106.7 μmol g^?1 for the template peptide and a K_d of 7.9 × 10^?6 M with a binding capacity of 36.0 μmol g^?1 for the ANP. Measurements of the binding kinetics reveal that MIPNPs reach protein‐adsorption equilibrium in 30 min. The MIPNPs are found to have a high specificity for ANP with little affinity for BSA or scrambled ANP peptide. The MIPNPs also recognize and adsorb ANP in cell‐culture medium spiked with ANP and in human plasma. Taken together, these results indicate that the MIPNPs have a high affinity and selectivity for ANP and can be used as a synthetic antibody for modulating ANP‐NPRA signaling in cancers.     

Zn(II)‐Protoporphyrin IX‐Based Photosensitizer‐Imprinted Au‐Nanoparticle‐Modified Electrodes for Photoelectrochemical Applications

The electropolymerization of thioaniline‐modified Au nanoparticles (NPs) on thioaniline monolayer‐functionalized electrodes in the presence of Zn(II)‐protoporphyrin IX yields bis aniline‐crosslinked Au NPs matrices that include molecular imprinted sites for binding the Zn(II)‐protoporphyrin IX photosensitizer. The binding of the photosensitizer yields photoelectrochemically active electrodes that produce anodic photocurrents in the presence of the electron donor benzohydroquinone. The efficient photocurrents formed in the presence of the imprinted electrode are attributed to the high‐affinity binding of the photosensitizer to the imprinted sites, K_a = 3.2 × 10⁶ m ^?1, and to the effective transport of the photoejected electrons to the bulk electrode via the bridged Au NPs matrix. Similarly, a N,N′‐dialkyl‐4,4′‐bipyridinium‐modified Zn(II)‐protoporphyrin IX photosensitizer‐electron acceptor dyad is imprinted in the bis aniline‐crosslinked Au NPs matrix. The photocurrent generated by the imprinted matrix is approximately twofold higher as compared to the photocurrent generated by the Zn(II)‐protoporphyrin IX‐imprinted Au NPs matrix. The efficient photocurrents generated in the presence of the bipyridinium‐modified Zn(II)‐protoporphyrin IX‐imprinted matrix are attributed to the effective primary charge separation of the electron–hole species in the dyad structure, followed by the effective transport of the photoejected electrons to the electrode via the bis aniline‐crosslinked Au NPs matrix.     

High‐Performance [001]c‐Textured PNN‐PZT Relaxor Ferroelectric Ceramics for Electromechanical Coupling Devices

[001]_C‐Textured 0.55Pb(Ni_1/3Nb_2/3)O₃–0.15PbZrO₃–0.3PbTiO₃ (PNN‐PZT) ceramics are prepared by the templated grain‐growth method using BaTiO₃ (BT) platelet templates. Samples with different template contents are fabricated and compared in terms of texture fraction, microstructure, and piezoelectric, ferroelectric and dielectric properties. High piezoelectric performance (d₃₃ = 1210 pC N^?1, d₃₃* = 1773 pm V^?1 at 5 kV cm^?1) and high figure of merit g₃₃?d₃₃ (21.92 × 10^?12 m² N^?1) are achieved in the [001]_C‐textured PNN‐PZT ceramic with 2 vol% BaTiO₃ template, for which the texture fraction is 82%. In addition, domain structures of textured PNN‐PZT ceramics are observed and analyzed, which provide clues to the origin of the giant piezoelectric and electromechanical coupling properties of PNN‐PZT ceramics.     

Selective Determination of Dopamine on a Boron‐Doped Diamond Electrode Modified with Gold Nanoparticle/Polyelectrolyte‐coated Polystyrene Colloids

Negatively charged gold nanoparticles (AuNPs) and a polyelectrolyte (PE) have been assembled alternately on a polystyrene (PS) colloid by a layer‐by‐layer (LBL) self‐assembly technique to form three‐dimensional (Au/PAH)₄/(PSS/PAH)₄ multilayer‐coated PS spheres (Au/PE/PS multilayer spheres). The Au/PE/PS multilayer spheres have been used to modify a boron‐doped diamond (BDD) electrode. Cyclic voltammetry is utilized to investigate the properties of the modified electrode in a 1.0 M KCl solution that contains 5.0 × 10^?3 M K₃Fe(CN)₆, and the result shows a dramatically decreased redox activity compared with the bare BDD electrode. The electrochemical behaviors of dopamine (DA) and ascorbic acid (AA) on the bare and modified BDD electrode are studied. The cyclic voltammetric studies indicate that the negatively charged, three‐dimensional Au/PE/PS multilayer sphere‐modified electrodes show high electrocatalytic activity and promote the oxidation of DA, whereas they inhibit the electrochemical reaction of AA, and can effectively be used to determine DA in the presence of AA with good selectivity. The detection limit of DA is 0.8 × 10^?6 M in a linear range from 5 × 10^?6 to 100 × 10^?6 M in the presence of 1 × 10^?3 M AA.     

Solar Cells with Enhanced Photocurrent Efficiencies Using Oligoaniline‐Crosslinked Au/CdS Nanoparticles Arrays on Electrodes

Different configurations of CdS nanoparticles (NPs) are linked to Au electrodes by electropolymerization of thioaniline‐functionalized CdS NPs onto thioaniline‐functionalized Au‐electrodes. In one configuration, thioaniline‐functionalized CdS NPs are electropolymerized in the presence of thioanline‐modified Au NPs to yield an oligoaniline‐crosslinked CdS/Au NPs array. The NP‐functionalized electrode generates a photocurrent with a quantum yield that corresponds to ca. 9%. The photocurrent intensities are controlled by the potential applied on the electrode, and the redox‐state of the oligoaniline bridge. In the oxidized quinoide state of the oligoaniline units, the bridges act as electron acceptors that trap the conduction‐band electrons that are transported to the electrode and lead to high quantum yield photocurrents. The reduced π‐donor oligoaniline bridges act as π‐donor sites that associate N,N′‐dimethyl‐4,4′‐bipyridinium, MV²⁺, by donor/acceptor interactions, K_a = 5270 M^?1. The associated MV²⁺ acts as an effective trap of the conduction‐band electrons, and in the presence of triethanolamine (TEOA) as an electron donor, high photocurrent values are measured (ca. 12% quantum yield). The electropolymerization of thioaniline‐functionalized Au NPs and thioaniline‐modified CdS NPs in the presence of MV²⁺ yields a MV²⁺‐imprinted NP array. The imprinted array exhibits enhanced affinities toward the association of MV²⁺ to the oligoaniline π‐donor sites, K_a = 2.29 × 10⁴ M^?1. This results in the effective trapping of the conduction‐band electrons and an enhanced quantum yield of the photocurrent, ca. 34%. The sacrificial electron donor, TEOA, was substituted with the reversible donor I₃^?. A solar cell consisting of the imprinted CdS/Au NPs array, with MV²⁺ and I₃^?, was constructed. The cell generated a photocurrent with a quantum yield of 4.7%.     

Quantification of Grafting Densities Achieved via Modular “Grafting‐to” Approaches onto Divinylbenzene Microspheres

The surface modification of divinylbenzene (DVB)‐based microspheres is performed via a combination of reversible addition fragmentation chain transfer (RAFT) polymerization and rapid hetero‐Diels–Alder (HDA) chemistry with the aim of quantifying the grafting densities achieved using this “grafting‐to” method. Two variants of the RAFT‐HDA concept are employed to achieve the functionalization of the microspheres. In the first approach, the microspheres are functionalized with a highly reactive diene, i.e., cyclopentadiene, and are subsequently reacted with polystyrene chains (number‐averaged molecular weight, M_n = 4200 g mol^?1; polydispersity index, PDI = 1.12.) that carry a thiocarbonyl moiety functioning as a dienophile. The functionalization of the microspheres is achieved rapidly under ambient conditions, without the aid of an external catalyst. The surface grafting densities obtained are close to 1.2 × 10²⁰ chains per gram of microspheres. In the second approach, the functionalization proceeds via the double bonds inherently available on the microspheres, which are reacted with poly(isobornyl acrylate) chains carrying a highly dienophilic thiocarbonyl functionality; two molecular weights (M_n = 6000 g mol^?1, PDI = 1.25; M_n = 26 000 g mol^?1, PDI = 1.26) are used. Due to the less reactive nature of the dienes in the second approach, functionalization is carried out at elevated temperatures (T = 60 °C) yet in the absence of a catalyst. In this case the surface grafting density is close to 7 chains nm^?2 for M_n = 6000 g mol^?1 and 4 chains nm^?2 for M_n = 26 000 g mol^?1, or 2.82 × 10¹⁹ and 1.38 × 10¹⁹ chains g^?1, respectively. The characterization of the microspheres at various functionalization stages is performed via elemental analysis for the quantification of the grafting densities and attenuated total reflectance (ATR) IR spectroscopy as well as confocal microscopy for the analysis of the surface chemistry.     

High‐Performance Organic Heterojunction Phototransistors Based on Highly Ordered Copper Phthalocyanine/para‐Sexiphenyl Thin Films

High‐performance organic heterojunction phototransistors are fabricated using highly ordered copper phthalocyanine (CuPc) and para ‐sexiphenyl (p ‐6P) thin films. The p ‐6P thin film plays an important role on the performance of CuPc/p ‐6P heterojunction phototransistors. It acts as a molecular template layer to induce the growth of highly ordered CuPc thin film, which dramatically improves the charge transport and decreases the grain boundaries. On the other hand, the p ‐6P thin film can form an effective heterojunction with CuPc thin film, which is greatly helpful to enhance the light absorption and photogenerated carriers. Under 365 nm ultraviolet light irradiation, the ratio of photocurrent and dark current and photoresponsivity of CuPc/p ‐6P heterojunction phototransistors reaches to about 2.2 × 10⁴ and 4.3 × 10² A W^?1, respectively, which are much larger than that of CuPc phototransistors of about 2.7 × 10² and 7.3 A W^?1, respectively. A detailed study carried out with current sensing atomic force microscopy proves that the photocurrent is predominately produced inside the highly ordered CuPc/p ‐6P heterojunction grains, while the photocurrent produced at the boundaries between grains can be neglected. The research provides a good method for fabricating high‐performance organic phototransistors using a combination of molecular template growth and organic heterojunction.     

Gold Core‐DNA‐Silver Shell Nanoparticles with Intense Plasmonic Chiroptical Activities

The strong plasmonic chiroptical activities of gold core‐DNA‐silver shell nanoparticles (NPs) are reported for the first time, using cytosine‐rich single‐stranded DNA as the template for the guidance of silver shell growth. The anisotropy factor of the optically active NPs at 420 nm reaches 1.93 × 10^?2. Their chiroptical properties are likely induced by the DNA–plasmon interaction and markedly amplified by the strong electromagnetic coupling between the gold core and silver shell.     

The Fabrication of a Photoresponsive Molecularly Imprinted Polymer for the Photoregulated Uptake and Release of Caffeine

A photoresponsive molecularly imprinted polymer (MIP) material is successfully fabricated from an azobenzene‐based functional monomer, 4‐[(4‐methacryloyloxy)phenylazo]benzoic acid (MPABA), using caffeine as a molecular template. The trans–cis photoisomerization properties of MPABA are retained after incorporation into the rigid 3D crosslinked polymer matrix. Substrate affinity of the MIP receptor sites is photoswitchable. This can be attributed to the photoisomerization of azobenzene chromophores within the MIP receptors, resulting in the alteration of their geometry and the spatial arrangement of their binding functionalities. The favorable binding constant of the MIP receptors for caffeine is 5.48 × 10⁴ M ^–1 in dimethylsulfoxide. The density of the caffeine‐specific receptor sites in the MIP material is 0.95 μmol (g MIP)^–1. Upon irradiation at 365 nm, 58.3 % of receptor‐bound caffeine is released from the MIP material. Subsequent irradiation at 440 nm causes 96.4 % of the released caffeine to be rebound by the MIP material. This near‐quantitative uptake of the released caffeine is evidence of the reversibility of the receptor‐site configuration and substrate affinity during the photoswitching of the azobenzene chromophores. Although the photoregulated substrate release and uptake processes are generally repeatable, a gradual reduction in the extent of substrate release and rebinding is observed. This may be caused by the slow deformation of MIP receptors during the course of repetitive photoswitching. The results of this work demonstrate the potential of stimuli‐responsive MIP materials as smart chemicals and as drug‐delivery systems.     

Novel Insoluble Organic Cathodes for Advanced Organic K‐Ion Batteries

Organic redox‐active molecules are inborn electrodes to store large‐radius potassium (K) ion. High‐performance organic cathodes are important for practical usage of organic potassium‐ion batteries (OPIBs). However, small‐molecule organic cathodes face serious dissolution problems against liquid electrolytes. A novel insoluble small‐molecule organic cathode [N,N′‐bis(2‐anthraquinone)]‐perylene‐3,4,9,10‐tetracarboxydiimide (PTCDI‐DAQ, 200 mAh g^?1) is initially designed for OPIBs. In half cells (1–3.8 V vs K⁺/K) using 1 m KPF₆ in dimethoxyethane (DME), PTCDI‐DAQ delivers a highly stable specific capacity of 216 mAh g^?1 and still holds the value of 133 mAh g^?1 at an ultrahigh current density of 20 A g^?1 (100 C). Using reduced potassium terephthalate (K₄TP) as the organic anode, the resulting K₄TP||PTCDI‐DAQ OPIBs with the electrolyte 1 m KPF₆ in DME realize a high energy density of maximum 295 Wh kg^?1_cathode (213 mAh g^?1_cathode × 1.38 V) and power density of 13 800 W Kg^?1_cathode (94 mAh g^?1 × 1.38 V @ 10 A g^?1) during the working voltage of 0.2–3.2 V. Meanwhile, K₄TP||PTCDI‐DAQ OPIBs fulfill the superlong lifespan with a stable discharge capacity of 62 mAh g^?1_cathode after 10 000 cycles and 40 mAh g^?1_cathode after 30 000 cycles (3 A g^?1). The integrated performance of PTCDI‐DAQ can currently defeat any cathode reported in K‐ion half/full cells.     

High‐Performance Ferroelectric Polymer Side‐Gated CdS Nanowire Ultraviolet Photodetectors

An efficient ferroelectric‐enhanced side‐gated single CdS nanowire (NW) ultraviolet (UV) photodetector at room temperature is demonstrated. With the ultrahigh electrostatic field from polarization of ferroelectric polymer, the depletion of the intrinsic carriers in the CdS NW channel is achieved, which significantly reduces the dark current and increases the sensitivity of the UV photodetector even after the gate voltage is removed. Meanwhile, the low frequency noise current power of the device reaches as low as 4.6 × 10^?28 A² at a source‐drain voltage V_ds = 1 V. The single CdS NW UV photodetector exhibits high photoconductive gain of 8.6 × 10⁵, responsivity of 2.6 × 10⁵ A W^?1, and specific detectivity (D*) of 2.3 × 10¹⁶ Jones at a low power density of 0.01 mW cm^?2 for λ = 375 nm. In addition, the spatially resolved scanning photocurrent mapping across the device shows strong photocurrent signals near the metal contacts. This is promising for the design of a controllable, high‐performance, and low power consumption ultraviolet photodetector.     

Metal Ion‐Terpyridine‐Functionalized L‐Tyrosinamide Aptamers: Nucleoapzymes for Oxygen Insertion into C?H Bonds and the Transformation of L‐Tyrosinamide into Amidodopachrome

A series of metal ion‐terpyridine‐modified L‐tyrosinamide aptamers (M^{n +} = Cu²⁺ or Fe³⁺) act as enzyme‐mimicking catalysts (nucleoapzymes) for oxygen‐insertion into C? H bonds and the transformation of L‐tyrosinamide into amidodopachrome. The reaction proceeds in the presence of H₂O₂ and coadded L‐ascorbic acid. In one series of experiments, the catalyzed oxidation of L‐tyrosinamide to amidodopachrome by a set of nucleoapzymes consisting of Fe³⁺‐ or Cu²⁺‐terpyridine complexes tethered directly or through a 4 × thymidine (4 × T) bridge, to the 5′‐ or 3′‐end of the 49‐mer L‐tyrosinamide aptamer or to a shorter 23‐mer L‐tyrosinamide aptamer is examined. All nucleoapzymes reveal catalytic Michaelis–Menten enzyme‐like activities and the separated Fe³⁺‐ or Cu²⁺‐terpyridine and L‐tyrosinamide aptamer units show only minute catalytic properties. The catalytic activities of the nucleoapzymes are attributed to the concentration of the L‐tyrosinamide substrate by the aptamer units in proximity to the catalytic sites (K_d = (14 ± 0.1) × 10^?6 m for all 49‐mer catalysts and K_d = (2.5 ± 0.1) × 10^?6 m and K_d = (0.8 ± 0.04) × 10^?6 m for the 23‐mer catalysts). Electron spin resonance experiments reveal that ?OH radicals and ascorbate radicals participate in the transformation of tyrosine derivatives to catechol products. An autocatalytic feedback mechanism for the amplified generation of the two radicals is suggested.     

Heat‐Transport Mechanisms in Superlattices

The heat transport mechanisms in superlattices are identified from the cross‐plane thermal conductivity Λ of (AlN)_x–(GaN)_y superlattices measured by time‐domain thermoreflectance. For (AlN)_{4.1 nm}–(GaN)_{55 nm} superlattices grown under different conditions, Λ varies by a factor of two; this is attributed to differences in the roughness of the AlN/GaN interfaces. Under the growth condition that gives the lowest Λ, Λ of (AlN)_{4 nm}–(GaN)_y superlattices decreases monotonically as y decreases, Λ = 6.35 W m⁻¹ K⁻¹ at y = 2.2 nm, 35 times smaller than Λ of bulk GaN. For long‐period superlattices (y > 40 nm), the mean thermal conductance G of AlN/GaN interfaces is independent of y, G ≈ 620 MW m⁻² K⁻¹. For y < 40 nm, the apparent value of G increases with decreasing y, reaching G ≈ 2 GW m⁻² K⁻¹ at y < 3 nm. MeV ion bombardment is used to help determine which phonons are responsible for heat transport in short period superlattices. The thermal conductivity of an (AlN)_{4.1 nm}–(GaN)_{4.9 nm} superlattice irradiated by 2.3 MeV Ar ions to a dose of 2 × 10¹⁴ ions cm⁻² is reduced by <35%, suggesting that heat transport in these short‐period superlattices is dominated by long‐wavelength acoustic phonons. Calculations using a Debye‐Callaway model and the assumption of a boundary scattering rate that varies with phonon‐wavelength successfully capture the temperature, period, and ion‐dose dependence of Λ.     

A Controllable Synthesis of Rich Nitrogen‐Doped Ordered Mesoporous Carbon for CO2 Capture and Supercapacitors

A controllable one‐pot method to synthesize N‐doped ordered mesoporous carbons (NMC) with a high N content by using dicyandiamide as a nitrogen source via an evaporation‐induced self‐assembly process is reported. In this synthesis, resol molecules can bridge the Pluronic F127 template and dicyandiamide via hydrogen bonding and electrostatic interactions. During thermosetting at 100 °C for formation of rigid phenolic resin and subsequent pyrolysis at 600 °C for carbonization, dicyandiamide provides closed N species while resol can form a stable framework, thus ensuring the successful synthesis of ordered N‐doped mesoporous carbon. The obtained N‐doped ordered mesoporous carbons possess tunable mesostructures (p6m and Im m symmetry) and pore size (3.1–17.6 nm), high surface area (494–586 m² g^?1), and high N content (up to 13.1 wt%). Ascribed to the unique feature of large surface area and high N contents, NMC materials show high CO₂ capture of 2.8–3.2 mmol g^?1 at 298 K and 1.0 bar, and exhibit good performance as the supercapacitor electrode with specific capacitances of 262 F g^?1 (in 1 M H₂SO₄) and 227 F g^?1 (in 6 M KOH) at a current density of 0.2 A g^?1.     

An Ultrahigh Responsivity (9.7 mA W−1) Self‐Powered Solar‐Blind Photodetector Based on Individual ZnO–Ga2O3 Heterostructures

Highly crystallized ZnO–Ga₂O₃ core–shell heterostructure microwire is synthesized by a simple one‐step chemical vapor deposition method, and constructed into a self‐powered solar‐blind (200–280 nm) photodetector with a sharp cutoff wavelength at 266 nm. The device shows an ultrahigh responsivity (9.7 mA W^?1) at 251 nm with a high UV/visible rejection ratio (R _{251 nm}/R _{400 nm}) of 6.9 × 10² under zero bias. The self‐powered device has a fast response speed with rise time shorter than 100 µs and decay time of 900 µs, respectively. The ultrahigh responsivity, high UV/visible rejection ratio, and fast response speed make it highly suitable in practical self‐powered solar‐blind detection. Additinoally, this microstructure heterojunction design method would provide a new approach to realize the high‐performance self‐powered photodetectors.     

Impact of Morphology on Charge Carrier Transport and Thermoelectric Properties of N‐Type FBDOPV‐Based Polymers

The impact of the chemical structure and molecular order on the charge transport properties of two donor–acceptor copolymers in their neutral and doped states is investigated. Both polymers comprise 3,7‐bis((E)‐7‐fluoro‐1‐(2‐octyl‐dodecyl)‐2‐oxoindolin‐3‐ylidene)‐3,7‐dihydrobenzo[1,2‐b:4,5‐b′]difuran‐2,6‐dione (FBDOPV) as electron‐accepting unit, copolymerized with 9,9‐dioctyl‐fluorene (P(FBDOPV‐F)) or with 3‐dodecyl‐2,2′‐bithiophene (P(FBDOPV‐2T‐C₁₂)). These copolymers possess an amorphous and semi‐crystalline nature, respectively, and exhibit remarkable electron mobilities of 0.065 and 0.25 cm² V^–1 s^–1 in field effect transistors. However, after chemical n‐doping with 4‐(1,3‐dimethyl‐2,3‐dihydro‐1H‐benzoimidazol‐2‐yl)phenyl)dimethylamine (N‐DMBI), electrical conductivities four orders of magnitude higher can be achieved for P(FBDOPV‐2T‐C₁₂) (σ = 0.042 S cm^?1). More charge‐transfer complexes are formed between P(FBDOPV‐F) and N‐DMBI, but the highly localized polaronic states poorly contribute to the charge transport. Doped P(FBDOPV‐2T‐C₁₂) exhibits a negative Seebeck coefficient of –265 µV K^?1 and a thermoelectric power factor (PF) of 0.30 µW m^?1 K^?2 at 303 K which increases to 0.72 µW m^?1 K^?2 at 388 K. The in‐plane thermal conductivity (κ_|| = 0.53 W m^?1 K^?1) on the same micrometer‐thick solution‐processed film is measured, resulting in a figure of merit (ZT) of 5.0 × 10^?4 at 388 K. The results provide important design guidelines to improve the doping efficiency and thermoelectric properties of n‐type organic semiconductors.     

A Molecularly Imprinted Copolymer Designed for Enantioselective Recognition of Glutamic Acid

A newly designed molecularly imprinted polymer (MIP) material was developed and successfully used as recognition element to fabricate a capacitive sensor for enantioselective recognition of glutamic acid (Glu). The MIP with a well‐defined structure was synthesized on a gold electrode in one step by electrochemical copolymerization of o‐phenylenediamine (o‐PD) and dopamine (DA) in the presence of template molecule Glu. The resulting MIP material was characterized with a potentiostatic frequency scan method, cyclic voltammetry, capacitance measurements, atomic force microscopy, and X‐ray photoelectron spectroscopy. The structure and recognition behaviour of the copolymer film to template molecule depended on its composition. The optimal composition was at the o‐PD to DA molar ratio of 3:2. With a potentiostatic time scan method the copolymer displayed high enantioselectivity and sensitivity to the stereoselective rebinding of L ‐ or D ‐Glu to their corresponding artificial receptor due to the exact definition of the imprint cavity. The capacitance response of the sensor for L ‐Glu or D ‐Glu was proportional to their concentration in the range of 16.7 to 250 μM . The enantiometric selectivity coefficients for L ‐Glu and D ‐Glu imprinted films against their respective enantiomers are 24 and 15, respectively. The resulting MIP capacitive sensors showed good reproducibility, stability and repeatability. This strategy opened a convenient way for preparation of enantioselective MIPs and recognition of enantiotropic molecules.     

Imidazolium Polyesters: Structure–Property Relationships in Thermal Behavior,Ionic Conductivity,and Morphology

New bis(ω‐hydroxyalkyl)imidazolium and 1,2‐bis[N‐(ω‐hydroxyalkyl)imidazolium]ethane salts are synthesized and characterized; most of the salts are room temperature ionic liquids. These hydroxyl end‐functionalized ionic liquids are polymerized with diacid chlorides, yielding polyesters containing imidazolium cations embedded in the main chain. By X‐ray scattering, four polyesters are found to be semicrystalline at room temperature: mono‐imidazolium‐C₁₁‐sebacate‐C₆ ( 4e ), mono‐imidazolium‐C₁₁‐sebacate‐C₁₁ ( 4c ), bis(imidazolium)ethane‐C₆‐sebacate‐C₆ ( 5a ), and bis(imidazolium)ethane‐C₁₁‐sebacate‐C₁₁ ( 5c ), all with hexafluorophosphate counterions. The other imidazolium polyesters, including all those with bis(trifluoromethanesulfonyl)imide (TFSI^?) counterions, are amorphous at room temperature. Room temperature ionic conductivities of the mono‐imidazolium polyesters (4 × 10^?6 to 3 × 10^?5 S cm^?1) are higher than those of the corresponding bis‐imidazolium polyesters (4 × 10^?9 to 8 × 10^?6 S cm^?1), even though the bis‐imidazolium polyesters have higher ion concentrations. Counterions affect ionic conduction significantly; all polymers with TFSI^? counterions have higher ionic conductivities than the hexafluorophosphate analogs. Interestingly, the hexafluorophosphate polyester, 1,2‐bis(imidazolium)ethane‐C₁₁‐sebacate‐C₁₁ ( 5c ), displays almost 400‐fold higher room temperature ionic conductivity (1.6 × 10^?6 S cm^?1) than the 1,2‐bis(imidazolium)ethane‐C₆‐sebacate‐C₆ analog ( 5a , 4.3 × 10^?9 S cm^?1), attributable to the differences in the semicrystalline structure in 5c as compared to 5a . These results indicate that semicrystalline polymers may result in high ionic conductivity in a soft (low glass tranition temperature, T_g) amorphous phase and good mechanical properties of the crystalline phase.     

Vectorially Imprinted Hybrid Nanofilm for Acetylcholinesterase Recognition

Effective recognition of enzymatically active tetrameric acetylcholinesterase (AChE) is accomplished by a hybrid nanofilm composed of a propidium‐terminated self‐assembled monolayer (Prop‐SAM) which binds AChE via its peripheral anionic site (PAS) and an ultrathin electrosynthesized molecularly imprinted polymer (MIP) cover layer of a novel carboxylate‐modified derivative of 3,4‐propylenedioxythiophene. The rebinding of the AChE to the MIP/Prop‐SAM nanofilm covered electrode is detected by measuring in situ the enzymatic activity. The oxidative current of the released thiocholine is dependent on the AChE concentration from ≈0.04 × 10^?6 to 0.4 × 10^?6m . An imprinting factor of 9.9 is obtained for the hybrid MIP, which is among the best values reported for protein imprinting. The dissociation constant characterizing the strength of the MIP‐AChE binding is 4.2 × 10^?7m indicating the dominant role of the PAS‐Prop‐SAM interaction, while the benefit of the MIP nanofilm covering the Prop‐SAM layer is the effective suppression of the cross‐reactivity toward competing proteins as compared with the Prop‐SAM. The threefold selectivity gain provided by i) the “shape‐specific” MIP filter, ii) the propidium‐SAM, iii) signal generation only by the AChE bound to the nanofilm shows promise for assessing AChE activity levels in cerebrospinal fluid.     

Hydrophilic Sparse Ionic Monolayer‐Protected Metal Nanoparticles: Highly Concentrated Nano‐Au and Nano‐Ag “Inks” that can be Sintered to Near‐Bulk Conductivity at 150 °C

Here, monolayer‐protected gold and silver nanoparticles with extremely high solvent dispersibility (over 200 mg mL^?1 in water and glycols) and low coalescence temperature (approximately 150 °C, measured by the percolation transition temperature T_p) are developed, to reach conductivities better than 1 × 10⁵ S cm^?1. These materials are suitable for inkjet and other forms of printing on substrates that may be solvent‐ and/or temperature‐sensitive, such as for plastic electronics, and as bus lines for solar and lighting panels. This is achieved using a new concept of the sparse ionic protection monolayer. The metal nanoparticles are initially protected by a two‐component mixed ligand shell comprising an ω‐functionalized ionic ligand and a labile ligand. These are selectively desorbed to give a sparse shell of the ω‐ionic ligands of ca. 25% coverage. Through a systematic study of different monolayer‐protected Au nanoparticles using FTIR spectroscopy, supported by XPS and DSC, it is shown that T_p is not determined by thermodynamic size melting or by surface area effects, as previously thought, but by the temperature when ca. 80% of the dense monolayer is eliminated. Therefore, T_p depends on the thermal stability and packing density of the shell, rather than the size of the metal core, while the solubility characteristics depend strongly on the exposed terminal group.