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The programed bimodal photoelectrochemical (PEC)-sensing platform based on DNA structural switching induced by targets binding to aptamers was innovatively designed for the simultaneous detection of mucin 1 (MUC1) and microRNA 21 (miRNA-21). To promote excellent current intensity as well as enhance the sensitivity of aptasensors, the evenly distributed WO3/Fe2O3 heterojunction was prepared as a transducer material, notably reducing the background signal response and extending the absorption of light. The multifunctional paper-based biocathode was assembled to provide a visual colorimetric assay. When introducing the integrated signal probe (ISP) composed of signal probe 1 (sP1) and signal probe 2 (sP2) on paper-based working units modified with gold nanoparticles (AuNPs), recognition sites of two targets were formed. In the presence of MUC1 protein, both sP1 and the target on the working unit were released into the corresponding colorimetric unit because of the DNA specific recognition. The horseradish peroxidase-streptavidin (HRP-SA) carried by free sP1 could oxidize 3,3',5,5'-tetramethylbenzidine (TMB) to turn a blue-colored oxidized TMB (oxTMB) in the presence of hydrogen peroxide (H2O2), which ultimately gained a higher photocurrent signal. Furthermore, miRNA-21 was modified on another working unit by binding with sP2, leading to changes in the current signal and thus enabling real-time detection of analytes with the assistance of a digital multimeter. The PEC aptasensor offered a wide dynamic range of 10 fg·mL-1-100 ng mL-1 for MUC1 and 0.1 pM-10 nM for miRNA-21, with a low detection limit of 3.4 fg·mL-1 and 36 fM, respectively. It laid the foundation for synchronous detection of multiple analytes and initiated a new way for the enhancement in modern next-generation disease diagnosis.

Developing efficient strategies for sensitive detection of microRNAs, the noncoding bioactive molecules and well-established biomarkers, has aroused great interests due to its great potential values in genetic and pathological analyses. Herein, a highly selective and disposable paper-based photoelectrochemical (PEC) sensor was rationally designed for sensing microRNA based on simple self-assembly of a target-triggerable DNA motor and nanozyme-catalyzed multistage biocatalytic precipitation reaction. Specifically, a brand-new type II heterojunction of TiO

Based on the prominent electrochemiluminescence (ECL) performances of molybdenum disulfide-graphene quantum dots (MoS2-GQDs) nanocomposite and combined with enzyme-assisted recycling DNA walker signal amplification, an “on-off” switch ECL biosensor was proposed for sensitive assay of specific DNA sequences. Noticeably, MoS2 with two-dimensional nanosheet structure increased the loading capacity of GQDs to support abundant hairpin DNA (H). The composites of MoS2 and GQDs facilitated the charge transfer in ECL process, which significantly improved the ECL signal to achieve an “on” state. Then, the DNA walker cyclic amplification was performed by adding the target DNA and exonuclease III (Exo III). Finally, the DNA2-Fc-DNA1 was introduced into the system as ECL signal quencher, turning the ECL signal into an “off” state. The sensitive assay of ultra-low concentration specific DNA sequences was realized according to the variation of ECL signal strength before and after the existence of target DNA. The proposed ECL biosensor showed a good linear relationship ranging from 1 nM to 100 aM with a detection limit of 25.1 aM, providing a powerful strategy for biomedical research and clinical analysis.

Real-time monitoring of neonicotinoid pesticide residues is of great significance for food security and sustainable development of the ecological environment. Herein, a paper-based surface-enhanced Raman scattering (SERS) amplified approach was proposed by virtue of multilayered plasmonic coupling amplification. The unique plasmonic SERS multilayer was constructed using three-dimensional (3D) silver dendrite (SD)/electropolymerized molecular identifier (EMI)/silver nanoparticle (AgNP) sandwich hybrids with multiple hotspots and a strong electromagnetic field in nanogaps. Dendritelike 3D silver materials with remarkably high accessible surface areas and the lightning rod effect constituted the first-order enhancement of paper-based sensors. Molecular identifiers coated upon an SD layer as the interlayer were used for target capture and enrichment. Subsequently, AgNPs featuring rough surface and local plasma resonance decorated as the top layer formed the secondary enhancement of the amplification strategy. As the most brilliant part, dendritelike 3D silver coupled with AgNPs has established double Ag layers to accomplish a multistage enhancement of SERS signals based on the superposition of their electromagnetic fields. Owning to the distinctive design of the multiple coupling amplification strategy, the fabricated SERS paper chips demonstrated impressive specificity and ultrahigh sensitivity in the detection of imidacloprid (IMI), with a detection limit as low as 0.02811 ng mL-1. More importantly, the multiple SERS enhancement paper chip holds great potential for automated screening of a variety of contaminants.

In this work, a target-induced signal quencher release strategy was proposed to construct a sensitive photoelectrochemical (PEC) sensor. To achieve this, Cu nanoclusters (NCs) featuring outstanding chemical performance were introduced and then pickled with acid to generate Cu2+ signal quenchers to quench the photocurrent response. Moreover, the three-dimensional (3D) hierarchical seaweed-like TiO2 nanomaterial (HSTN) was prepared for the first time and served as the electron transporting material, which could provide the highly efficient pathways for the transfer of photoinduced electrons. Meanwhile, in order to extend the light response to the visible range, narrow band gap CdS quantum dots (QDs) were employed to form a HSTN/CdS heterojunction. In addition, magnetic bead (MB) modified PSA aptamer (MB-Apt) was used as the auxiliary structure which could combine with DNA-Cu NCs through specific recognition. When the target PSA was found, the MB-Apt would bond with PSA due to the relatively large interaction force, triggering the release of Cu NCs. With the aid of acid, the Cu NCs could be converted to Cu2+ and then react with CdS to form CuxS, decreasing the photocurrent signal. Consequently, the concentration of PSA could be accurately detected through monitoring the change of photocurrent. This work provides an ingenious idea for the fabrication of highly sensitive PEC sensors.

In this work, a triggerable H2O2-cleavable fluid switch mediated paper-based biochip, being amenable to multiplexing and quantitative analysis with the dual-response output of visual screening and ...

By controlling target-induced signal quencher release, a label-free and modification-free microfluidic paper based photoelectrochemical analytical device (μ-PAD) for cardiac troponin-I (cTnI) detection was designed for the first time. To achieve it, cellulose paper based single-crystalline three-dimensional aloe like TiO2 arrays (PSATs) were firstly fabricated as the electron transporting material, providing direct pathways for the charge carriers transfer, and subsequently coupled with CdS to form PSATs/CdS heterojunction for extending the solar spectrum response. Meanwhile, positive charged mesoporous silica nanoparticles (PMSNs) were prepared as the nanocarrier to efficient entrap the Cu2+ which could be regarded as signal quencher due to their reaction with CdS to form CuxS. Single stranded DNAs (ssDNAs), which could bind specifically with the target of cTnI, were then introduced to couple with the PMSNs and used as the bio-gate to encapsulate the signal quencher of Cu2+, endowing the functional PMSNs with responsiveness to cTnI. When the cTnI existed, the ssDNAs were dissociated from PMSNs due to the formation of cTnI-ssDNAs complexes, triggering controllable release of the trapped Cu2+, and further decreasing the photocurrent signal caused by the formation of CuxS. Accordingly, the concentration of cTnI could be accurately quantified via the photocurrent, realizing the target-induced modification-free μ-PAD assay. We believe this work could provide an ingenious idea to construct the easy-to-use novel modification-free μ-PAD.

The programed bimodal photoelectrochemical (PEC)-sensing platform based on DNA structural switching induced by targets binding to aptamers was innovatively designed for the simultaneous detection of mucin 1 (MUC1) and microRNA 21 (miRNA-21). To promote excellent current intensity as well as enhance the sensitivity of aptasensors, the evenly distributed WO

A paper-based electrochemiluminescence (ECL) biosensor characterized by the signal amplification of reticular DNA-functionalized PtCu nanoframes (DNA-PtCuTNFs) and analyte-triggered DNA walker was developed for sensitive streptavidin assay. Silver microflower functionalized paper-based sensing platform was prepared to fix the hairpin strand (S1). With addition of the streptavidin, plenty of DNA walkers consisting of the walking strands (S2) labeled with biotin and streptavidin were established, which protected S2 from digestion via the terminal protection mechanism. The sequential introduction of the DNA walker and capture probe initiated the hairpin structure opening of S1 and strand displacement reaction (SDR) happening, causing the S2 release. Subsequently, S1 hybridized with S3. The free S2 further hybridized with adjacent S1 to trigger the next cycle. After multiple cycles, the DNA-PtCuTNFs, the fire-new signal enhancer, with remarkable peroxidase activity, were successfully attached onto the paper electrode via metal-catalyst-free click chemistry. Based on the SDR of the DNA walker and the catalysis of DNA-PtCuTNFs, a significantly boosted ECL signal of luminol was obtained. Under the optimal conditions, the developed sensor for streptavidin assay exhibited a low detection limit of 33.4 fM with a linear range from 0.1 pM to 0.1 μM. Graphical abstract.

The exploitation of self-powered devices that get rid of the power source restriction represents the development tendency of sensing systems. Herein, a paper-supported glucose/O2 biofuel cell (BFC)...

MicroRNAs (miRNAs) are a class of significant biomarkers; however, it is still a huge challenge to express them accurately. Herein, a fluorescent/colorimetric dual-model biosensor based upon the quenching effect of graphitic carbon nitride on palladium nanoclusters (Pd NCs) on the platform of a microfluidic paper-based analytical device was built for the detection of miRNAs. On the one hand, Pd NCs could catalyze a chromogenic reaction so that preliminary detection was achieved by the naked eye. On the other hand, the fluorescence analysis combined with nucleic acid cycle signal amplification was required to get precise result and the detection limit is 3 fM, which was superior to the previous method. What's more, this biosensor could be designed to detect other miRNAs via changing the corresponding aptamer sequences. Therefore, the as-constructed biosensor supplies a versatile platform to conduct point-of-care detection of miRNAs with outstanding performance.

Okadaic acid (OA) is the main toxic component of diarrhetic shellfish poisoning, which can cause vomiting, diarrhea, and even induce tumor formation in people who accidentally ingest it. To strengthen the front-end prevention and control of shellfish safety, a surface-enhanced Raman scattering (SERS) paper swab based on high-affinity binding and high-specific recognition performance of nucleic acid aptamer was proposed to detect OA by virtue of enhanced multistage plasmon coupling effect. Composite resonance bilayer constituted by evenly dispersed gold nanoparticles integrating with a three-dimensional (3D) succulent-like silver particle was facilely manufactured in-situ on the paper substrate. Subsequently, with the assistance of 3D nanotopography structured silver nano-octahedra connected on the signal probe, a multistage SERS signal cooperative amplification platform was formed with about 10-fold enhanced Raman intensity higher than either single-layer substrate. Owning to the unique strategy of superimposed signal enhancement, such paper SERS aptasensor possessed admirable specific recognition and sensitivity has been successfully used in the on-site quantization of OA, with a detection limit of 0.31 ng/mL. Furthermore, the construction of the SERS paper swab is of great significance to the promotion of rapid on-site analysis approach of OA content in seafood by customs, seafood market supervision departments and ordinary consumers.

Integrating ratiometric photoelectrochemical (PEC) techniques with paper microfluidics to construct a ratiometric PEC paper analytical device for practical application is often restricted by the grave dependence of ratiometric assay on photoactive materials and low mass-transfer rates of the paper channel. Herein, a universal donor/acceptor-induced ratiometric PEC paper analytical device with a hollow double-hydrophilic-walls channel (HDHC) was fabricated for high-performance microRNA-141 (miRNA-141) quantification. Concretely, a photoanode and photocathode were integrated on the paper-based sensing platform in which the photocathode served as a biosensing site for the pursuit of higher selectivity. For formulation of a cascading signal amplification strategy, a unique duplex-specific nuclease-induced target recycling reaction was engineered for the output of a double amount of all useful DNA linkers instead of conventional output of only one available DNA product, which could guarantee the output of abundant DNA linkers with the initiation of a cascade of hybridization chain reaction on both the trunk and branch in the presence of miRNA-141. Then the formed dendriform polymeric DNA duplex structures were further decorated with glucose oxidase (GOx)-mimicking gold nanoparticles by the electrostatic interaction to form a branchy gold tree (BGT). Profiting from the perfect GOx-mimicking activity of BGT and high mass-transfer rates of HDHC, the cathodic photocurrent from Ag

In this work, a triggerable H

Interventional medical detection techniques require expensive devices and cause inconvenience and discomfort to the human body, which restricts their application to the frequency and duration of measurements. A noninvasive respiration test is urgently required for the next-generation medical technologies in early disease warning and postoperative monitoring. This article describes a noninvasive and wearable sensing device that shows high sensitivity toward acetone in respiratory gases with excellent stability, low energy consumption, and reliable flexibility. To obtain such a sensor, the organic semiconductor compound La(TBPP)(TBNc) (TBPP = tetrakis(4

In this work, a peptide-based photoelectrochemical (PEC) biosensor was constructed based on CdTe/TiO2 sensitized structure as electrode and CuS nanocrystals as signal amplifier for the ultrasensitive detection of protein. After peptide was fixed to the CdTe/TiO2 electrode surface, the double-helix DNA (dsDNA) was immobilized at the end of the peptide and used as a carrier to immobilize the doxorubicin-copper sulfide nanocrystals (Dox-CuS) conjugates. As a proof of concept, prostate specific antigen (PSA) has been chosen as the model. In absence of PSA, CuS nanocrystals could consume electron donors and exciting light energy. Additionally, the steric hindrance effect of biomacromolecules hindered the movement of electron donors to the photoelectrode. Eventually, the photoelectric response signal was reduced, and the biosensor was in a “signal off” state. When PSA existed, the PSA specifically cleaved the peptide, and DNA/Dox-CuS probes were released from the electrode surface, resulting in a “signal on” state. The PEC biosensor revealed good specificity, stability, and reproducibility, and it exhibited excellent application in PSA analysis with a linear range from 0.005 to 20 ng mL−1 and a low detection limit of 0.0015 ng mL−1. This PEC biosensor may have potential applications in bioanalysis, disease diagnostics, and clinical biomedicine.

A paper-based surface enhanced Raman scattering (SERS) sensor with synergistic enhancement strategy for selective detection of tartrazine in food products has been established in this work. For economic and mass production purposes, paper substrates were firstly installed with a silver layer to endow the paper with electroconductibility and dense plasmonic hotspots. A biomimetic recognizer (BR) membrane was attached upon the Ag paper as specific identification device, and a layer of high-density of silver nanoparticles (AgNPs) was decorated on the surface of Ag/BR paper through in-situ growth method to form a sandwich structure. Since the double layer of Ag/AgNPs demonstrated excellent local plasma resonance effect, combined with the identification function of BR, it made the paper SERS sensor emerge incredible Raman synergistic enhancement response on tartrazine molecules embraced the plasma nanoparticles. Thus, the synergistically enhanced Ag/BR/AgNPs paper SERS sensor was achieved and applied in on-site test of tartrazine in Children's snacks. The linear range (0.3∼10 μg mL−1) and the limit of detection (0.1138 μg mL−1) of the SERS paper strip could be applied as a screening or occupational cut-off of tartrazine (100 μg mL−1) for reference. In addition, the proposed paper sensor can be a potential candidate for multicomponent screening and is suitable for mass production and promotion.

The exploitation of self-powered devices that get rid of the power source restriction represents the development tendency of sensing systems. Herein, a paper-supported glucose/O

By controlling target-induced signal quencher release, a label-free and modification-free microfluidic paper based photoelectrochemical analytical device (μ-PAD) for cardiac troponin-I (cTnI) detection was designed for the first time. To achieve it, cellulose paper based single-crystalline three-dimensional aloe like TiO

Inspired by the design of folding greeting cards and tissue drawing covers, a photoelectrochemical (PEC) lab-on-paper device with a controllable fluid separator, producing both reaction zone and detection zone, was explored for ultrasensitive detection of adenosine 5′-triphosphate (ATP) via mimic peroxidase-transfer enhancement of photocurrent response. To realize it, the DNA1, aptamer, and DNA2 as well as the mimic peroxidase of G-quadruplex/hemin modified Au nanocubes were linked on the graphene oxide-functionalized reaction zone via the DNA hybridization. Meanwhile, three-dimensional CuO nanoflowers (CuO NFs) as a photoactive material with outstanding electron transfer ability and absorption of light were grown in situ on the detection zone, providing a PEC active interface. Besides, an innovative fluid separator was elaborately designed by assembling a strip of paper with a hydrophilic channel, providing an effective way to bridge the gap between the two zones with a controllable drawing way, which could successfully avoid the signal interference caused by modifying biomolecules layer by layer on photosensitive materials. In the presence of ATP, the G-quadruplex/hemin modified in the reaction zone was dissociated due to the specific recognition of ATP with aptamer and released into the detection zone with the assistance of controllable fluid separator. The free G-quadruplex/hemin could catalyze hydrogen peroxide to generate oxygen for the consumption of photo-induced electrons from CuO NFs, which could further promote the electron-hole carriers separation efficiency, and eventually resulting in the enhancement of PEC signal. The proposed PEC lab-on-paper device could be employed for specific detection of ATP in the range from 5.0 to 3.0 × 103 nM with a detection limit of 2.1 nM.

Based on spin-polarized first-principles density functional theory in conjunction with the nonequilibrium Green's function method, the spin transport properties of transition metal (TM)–dibenzotetraaza[14]annulene (DBTAA) complexes (TM = Ti, V, Cr, Mn, Fe, Co, Ni, and Cu) sandwiched between two Au electrodes are investigated. The results show that Fe– and Co–DBTAA can display perfect spin filtering behavior in a wide bias voltage region. Moreover, it is found that the connected position of anchoring groups on the complexes affect significantly the spin filtering efficiency. The observed spin filtering behavior is explained by the spin-resolved transmission spectrum and molecular projected self-consistent Hamiltonian state analyses.

Using both the first-principles method and the tight-binding method, we have carried out detailed studies on the electronic properties of silicene superlattices. According to the band-folding picture, in the hexagonal silicene superlattice (M,N) when both M and N are integer multiples of 3, the simultaneous folding of K and K′ points to the Γ point results in the fourfold degeneracy. In the orthogonal one [P,Q], the fourfold degeneracy occurs if Q = 3q (q is an integer) is satisfied. By introducing degenerate perturbation to remove the fourfold degeneracy, the bandgap could be opened no matter whether the inversion symmetry remains or not. For the other cases, the bandgaps could be kept closed by the inversion symmetry preservation. Besides, the studied transport properties confirm the bandgap tuning by applying degenerate perturbation to the silicene superlattice. The new bandgap opening mechanism with degenerate perturbation could benefit further experimental studies of the silicene-based nanostructures for applications in nanoelectronics.

By using the nonequilibrium Green's function formalism in combination with the density functional theory, we have investigated the spin transport properties of a 4H-TAHDI-based multifunctional spintronic device constructed by contacting a 4H-TAHDI molecule with two ferromagnetic zigzag-edge graphene nanoribbon electrodes. The results show that perfect giant magnetoresistance, spin-filtering, bipolar spin-rectifying, and negative differential resistance effects can be realized simultaneously. The mechanisms were proposed for these interesting phenomena. Our results demonstrate that this system holds promise in the design of a high-performance multifunctional single-molecule spintronic device.

One novel electrochemistry-molecular imprinting sensor for determining tert-butylhydroquinone (TBHQ) in foodstuff was developed. TBHQ-imprinted core–shell nanoparticles (TICSNs) were fabricated using silica nanoparticles as core material. The silica nanoparticles were modified with (3-chloropropyl) trimethoxysilan and polyethylenimine, respectively, and polymerised to form the TICSNs with ethylene glycol dimethacrylate as cross-linker. The specific core–shell structure demonstrates extremely high specific surface area which greatly increases the effective binding sites and improves the recognition capability for model molecules. Under the optimal conditions, the linear range of the calibration curve was 0.1–50.0 mg kg −1 with the detection limit of 0.27 mg kg −1 . The sensor has been successfully applied to the determination of TBHQ in food samples and achieved high sensitivity and selectivity.

By applying the nonequilibrium Greenʼs function formalism combined with density functional theory, we have investigated the electronic transport properties of two nitrogen-doped armchair graphene nanoribbon-based junctions M1 and M2. In the left part of M1 and M2, nitrogen atoms are doped at two edges of the nanoribbon. In the right part, nitrogen atoms are doped at one edge and at the center for M1 and M2, respectively. Obvious rectifying and negative differential resistance behaviors are found, which are strongly dependent on the doping position. The maximum rectification and peak-to-valley ratios are up to the order of 10 4 in M2.

On the basis of first-principles density functional theory and non-equilibrium Green's function technique, we have investigated the effects of a mono-vacancy on the electronic transport properties of the carbon nanotube/boron nitride nanotube heterostructures. The results show that the electronic transport properties are strongly dependent on the position of the mono-vacancy, and the negative differential resistance and rectifying performances can be strengthened or weakened alternately with the position change of the mono-vacancy. Moreover, the performance change is more significant when the mono-vacancy occurs on the carbon nanotube part. These interesting phenomena are explained in terms of the evolution of the transmission spectrum with applied bias combined with molecular projected self-consistent Hamiltonian states analysis.

Using first-principles density functional theory and non-equilibrium Green's function formalism for quantum transport calculation, we have investigated the electronic transport properties of (8,0), (9,0) and (13,0) zigzag single-walled carbon nanotube junctions with one undoped and one nitrogen-doped zigzag carbon nanotube electrode. Our results show that the transport properties are strongly dependent on the magnitude of energy gap of carbon nanotube. Large rectifying behavior can be obtained in the junction with large energy gap. The observed rectifying behavior are explained in terms of the evolution of the transmission spectra and energy band structures with applied bias voltage combined with molecular projected self-consistent Hamiltonian eigenstates analysis.

Using first-principles density functional theory and non-equilibrium Green's function formalism for quantum transport calculation, we have investigated the electronic transport properties of heteronanotubes by joining a zigzag (6,0) carbon nanotube and a zigzag (6,0) boron nitride nanotube with different atomic compositions and joint configurations. Our results show that the atomic composition and joint configuration affect strongly the electronic transport properties. Obvious negative differential resistance behavior and large rectifying behavior are obtained in the heterostructure with certain composition and joint configuration. Moreover, tube length and tube radius can affect strongly the observed NDR and rectifying behaviors. The observed negative differential resistance and rectifying behaviors are explained in terms of the evolution of the transmission spectrum with applied bias combined with molecular projected self-consistent Hamiltonian states analysis.

By applying the nonequilibrium Green function formalism combined with density functional theory, we have investigated the electronic transport properties of the C60 dimer and its endohedral complex Li@C60 dimer. Our results show that the doping of Li atoms significantly changes the transport properties of the C60 dimer. Negative differential resistance is found in such systems. Especially, the doping of Li atoms can lead to a much larger negative differential resistance at much lower bias, and it is quite evident from the plot of differential conductance versus bias. The negative differential resistance behavior is understood in terms of the evolution of the transmission spectrum and projected density of states spectrum with applied bias combined with molecular projected self-consistent Hamiltonian states analyses.

In this paper, a novel chemiluminescence–molecular imprinting (CL–MI) sensor for determination of fenpropathrin in foodstuff has been developed. Fenpropathrin-imprinted porous hollow microspheres (FIPHMs) were prepared using mesoporous silica particles as cores. The mesoporous silica particles were modified by 3-Aminopropyltrimethoxysilane (APTS) and acrylyl chloride, respectively, and coated with a tunable thickness layer of template molecules and functional monomer by precipitation polymerization. The cores were finally dissolved to form the hollow structure of FIPHMs. The specific hollow structure made FIPHMs have highly dense of effective binding sites at both internal and external surfaces which enhanced its adsorption abilities and enrichment towards fenpropathrin molecule. The CL–MI flow sensor was built by packing the FIPHMs into a self-made polymethyl methacrylate flow cell. Tests showed that the prepared sensor achieved high sensitivity and selectivity. Under the optimal conditions, the relative CL intensity was linear with fenpropathrin concentration from 5.0 × 10 −8 to 1.5 × 10 −5 g mL −1 and with a detection limit of 3.07 × 10 −8 g mL −1 . The novel sensor has been successfully applied to the determination of fenpropathrin in food samples.

A sensitive and rapid technique for high selectivity detection of tetradifon has been developed. This method is based on a new kind of hollow shell molecularly imprinted (MI) polymer. In this method, the new hollow shell MI polymer has bigger specific surface areas compared with the traditional one based on the double-sides hollow microspheres structure. The proposed method has the advantage of wider linear range and lower limit of detection compared with the traditional one. The change in chemiluminescence (CL) intensity is linearly proportional with the concentration of tetradifon in the range 0.1∼12 μg mL−1 and the detection limit has reached 0.0483 μg mL−1. The new MI-CL sensor has been successfully applied to the determination of residual tetradifon in food and the results obtained compare well with those by other methods.

Novel molecularly imprinted core–shell microspheres were synthesized using hollow silica microspheres as the core. Because of the molecularly imprinted core–shell microspheres, the effective binding sites at the surface of the shells were sharply increased; and, the recognition capability for template molecules was greatly improved. Based on this, a novel chemiluminescence sensor was established and successfully applied in the detection of trace pendimethalin in foodstuffs. The proposed sensor exhibited excellent selectivity, good sensitivity and simple operation. High throughput sample detection was realized with satisfactory results.

A novel chemiluminescence (CL) sensor for the determination of glyphosate (GLY) was made up based on molecularly imprinted polymer (MIP). The molecularly imprinted microspheres (MIMs) with a small dimension which possess extremely high surface-to-volume ratio were synthesized using precipitation polymerization with GLY as template. And then the MIMs were modified on glass sheets, which were placed at the bottom of wells of microplate as the recognizer. Subsequently, a highly selective and high throughput chemiluminescence (CL)-molecular imprinting (MI) sensor for detection of GLY was achieved. Influencing factors were investigated and optimized in detail. The method can perform 96 independent measurements sequentially in 10 min and the limit of detection (LOD) for GLY was 0.046 μg mL−1. The relative standard deviation (RSD) for 11 parallel measurements of GLY was 4.68%. The results show that CL-MI sensor can become a useful analytical technology for quick molecular recognition.

Based on the first-principles density functional theory combined with the non-equilibrium Green's function method, we have studied the spin-polarized and thermospin-polarized transport properties of phthalocyanine (Pc) dimer based molecular junction with different transition metal (TM = Mn, Fe, Co, Ni) atoms. Our results show that the spin-polarized and thermospin-polarized transport properties can be effectively tuned by changing the central TM atoms, and only the MnPc dimer system exhibits perfect spin/thermal-spin filtering and sizeable giant magnetoresistance (GMR)/thermal-GMR effects. Meantime, the MnPc dimer system reveals a low-bias negative differential resistance effect under the parallel magnetic configuration. These findings suggest that the MnPc dimer system has great potential in developing the high-performance multifunctional spintronic and spin caloritronic devices.

Ag2S/CdS/TiO2 hybrid nanotube array films (Ag2S/CdS/TNTs) were prepared by selectively depositing a narrow-gap semiconductor—Ag2S (0.9 eV) quantum dots (QDs)—in the local domain of the CdS/TiO2 nanotube array films by spotting sample method (SSM). The improvement of sunlight absorption ability and photocurrent density of titanium dioxide (TiO2) nanotube array films (TNTs) which were obtained by anodic oxidation method was realized because of modifying semiconductor QDs. The CdS/TNTs, Ag2S/TNTs, and Ag2S/CdS/TNTs fabricated by uniformly depositing the QDs into the TNTs via the successive ionic layer adsorption and reaction (SILAR) method were synthesized, respectively. The X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectrum (XPS) results demonstrated that the Ag2S/CdS/TNTs prepared by SSM and other films were successfully prepared. In comparison with the four films of TNTs, CdS/TNTs, Ag2S/TNTs, and Ag2S/CdS/TNTs by SILAR, the Ag2S/CdS/TNTs prepared by SSM showed much better absorption capability and the highest photocurrent density in UV-vis range (320~800 nm). The cycles of local deposition have great influence on their photoelectric properties. The photocurrent density of Ag2S/CdS/TNTs by SSM with optimum deposition cycles of 6 was about 37 times that of TNTs without modification, demonstrating their great prospective applications in solar energy utilization fields.

A new analytical approach for detecting diaminopyridine derivatives has been constructed using a molecular imprinting-electrochemical sensor. Opposed to the conventional strategy of employing diaminopyridine as the functional monomer and uracil derivatives as the target analyte, in the current study, the 2,6-Diaminopyridine-imprinted core-shell nanoparticles were synthesized with 2,6-Diaminopyridine as the template molecule and 6-aminouracil as the functional monomer. Graphene and ionic liquid which can assist 2,6-Diaminopyridine-imprinted core-shell nanoparticles in electrochemical reaction kinetics by increasing conductivity have been introduced to form one of the electrode modified layers. The proposed analytical method has been applied in 2,6-Diaminopyridine detection in hair-dyes and demonstrated appropriate sensitivity and selectivity, with a linear range of 0.0500-35.0 mg kg(-1) and a detection limit as low as 0.0275 mg kg(-1).

Uni-lamellar and multi-lamellar vesicles were prepared by the enantiomers of a biological molecule, l -lysine or d -lysine, with a double-tail weak monoacid, di-(2-ethylhexyl) phosphoric acid (abbreviated as DEHPA), in water. With the addition of DEHPA to lysine aqueous solutions, ion-pairs are formed through the acid-base reaction between the lysine cations and DEHP− anions. The self-assembled vesicles were proved to be driven by the hydrogen bonding between the side-chain amino groups in lysine molecules and the polar groups of DEHP− species. The combination of DEHPA and lysine through electrostatic interactions and hydrogen bonding reduces the cross-sectional area of the hydrophilic groups, improving the surface activity and inducing a microstructural transition from primitive aggregates to micelles, and to vesicles in solution. Due to the chirality of the lysine molecules, the aggregates exhibited diverse chiral properties along with the microstructural transitions.

Novel fenvalerate double-sided hollow molecularly imprinted microspheres (fenvalerate-DHMIMs) were fabricated by in situ polymerization with the help of mesoporous silica microspheres (MSMs) in this paper for the very first time. Scanning electron microscope was employed to characterize the surface morphology of the fenvalerate-DHMIMs. Taking advantage of the quenching effect of fenvalerate on the luminol-H(2)O(2)-NaOH chemiluminescence system, a new model was established to determine fenvalerate by a highly selective flow injection chemiluminescence method. The traditional flow-through cell was replaced by a novel Y-shaped column. The chemiluminescence intensity was linear with fenvalerate concentration over the range of 5.0 × 10(-8) to 2.0 × 10(-5) g mL(-1) and the detection limit was 2.2 × 10(-8) g mL(-1). The relative standard deviation (RSD) for the determination of 2.0 × 10(-6) g mL(-1) fenvalerate was 1.4% (n = 11). The proposed method was applied to the determination of fenvalerate in real samples with satisfactory results.

A simple and convenient on-line molecular imprinted solid-phase extraction flow-injection fluorescence sensor was developed in this study. Florfenicol (FF)-imprinted polymer was prepared by self-assembly with acrylamide (AM) as functional monomer and ethylene glycol dimethacrylate (EGDMA) as cross-linker. The binding characteristics of the imprinted polymer to florfenicol were evaluated by equilibrium binding experiments, and the morphology of the imprinted polymer was studied by scanning electron microscope (SEM). Fluorescence intensity of 3-p-nitrylphenyl-5-(2'-sulfonophenylazo) rhodanine (4NRASP) and bovine serum albumin (BSA) was inhibited by FF. Under optimum conditions the intensity of fluorescence shows a linear relationship with the concentration of FF over the range of 1.2x10(-6) to 2.6x10(-5)gmL(-1) with a regression equation of DeltaI=23.54+17.86c (c 10(-6)gmL(-1)) (r=0.9965, n=6). The low detection limit of FF was found to be 3.4x10(-7)gmL(-1) according to 11 parallel determinations for the blank solution. The relative standard deviation for the determination of 2.0x10(-6)gmL(-1) FF solution was 3.5% (n=11). This proposed sensor could be satisfactorily applied to the determination of FF in liver and meat samples.

By using the nonequilibrium Green's function formalism combined with the density functional theory, we have investigated the spin-polarized transport properties of a planar four-coordinate Fe complex sandwiched between two zigzag-edge graphene nanoribbon (ZGNR) electrodes, where the ZGNRs are modulated by external magnetic field. The results show that the system can exhibit perfect dual spin-filtering and spin-rectifying effects at a wide bias range, giant magnetoresistance effect with large magnetoresistance ratio at small bias, and obvious negative differential resistance behavior. The mechanisms are proposed for these phenomena.

Using the nonequilibrium Green's function formalism combined with density functional theory for quantum transport calculation, we have investigated the electronic transport properties of three endofullerenes Na@C60C60[@F, Na@C60C60, and F@C60C60. The results show that the electronic transport properties of these endofullerenes are strongly dependent upon the species inside the fullerene. A large rectifying behavior is observed in Na@C60C60, while Na@C60C60[@F and F@C60C60 can only present very weak rectification. It is revealed that the alignment between the molecular levels of two C60s moieties with the applied bias is the main cause of the large rectification in Na@C60C60.

A novel chemiluminescence-molecular imprinting (CL–MI) sensor was developed for the sequential determination of two pesticide residue components. One “X” shaped multi-branch flow cell was used to pack two kinds of molecularly imprinted microspheres (MIMs) as the recognition device. The MIMs were synthesized by precipitation polymerization with carbofuran and omethoate as templates, acrylamide as the functional monomer and ethylene glycol dimethacrylate as the cross-linker. The simple operation of the method enhanced the analysis efficiency and the combination of CL and MI resulted in good sensitivity and high selectivity. The application of the CL-MI sensor has very wide prospects. Calibration graphs were obtained over the concentration ranges 4.0 × 10−8 to 9.0 × 10−6 g mL−1 and 1.0 × 10−7 to 9.0 × 10−6 g mL−1 for carbofuran and omethoate, respectively. The limits of detection were 2.5 × 10−8 g mL−1 for carbofuran and 4.2 × 10−8 g mL−1 for omethoate. The proposed method was successfully applied to the sequential determination of both compounds in foodstuff.