Pinggui Yi

Porous NbO-type metal–organic framework with inserted acylamide groups exhibiting highly selective CO2 capture

A new expanded microporous NbO-type metal–organic framework [Cu2(BDPT4−)]n with inserted acylamide groups has been designed and synthesized, which shows both a large CO2-uptake capacity (156.4 cm3 g−1 at 1 bar) and a high selectivity for CO2 over N2 (39.8) and CH4 (7.2) at 273 K.

A novel label-free multi-throughput optical biosensor based on localized surface plasmon resonance

A novel and sensitive multi-throughput localized surface plasmon resonance (MLSPR) biosensor was developed for the first time. Various gold nanorods with different aspect ratios were used to fabricate the optical sensor. Five kinds of gold nanorods with different aspect ratios were chosen to construct five throughputs of MLSPR. Various LSPR peaks imply that different acceptor-ligand pairs can be detected simultaneously in the wavelength range from 530 to 940nm. The biosensor immobilized on glass slides was applied to label-free detection between acceptor and ligand. The MLSPR-based optical biosensor can be used to detect three antigen-antibody pairs simultaneously. The biosensor proposed herein is easy to fabricate, and its operation procedure is convenient as labeling procedure is unnecessary.

Synthesis and characterization of novel reversible photoswitchable fluorescent polymeric nanoparticles via one-step miniemulsion polymerization.

In the present study, novel polymeric nanoparticles of ca. 55 nm in diameter with reversibly photoswitchable fluorescence properties were synthesized using a facile one-step miniemulsion polymerization, in which the donor of fluorescence resonance energy transfer (FRET), 4-methamino-9-allyl-1,8-naphthalimide (MANI), and the acceptor, spiropyran-linked methacrylate (SPMA), were covalently incorporated into a polymeric matrix during the polymerization process. The fluorescence emission of MANI dye in nanoparticles can be reversibly switched using the alternating irradiation of UV and visible light, which can induce the structural interconversion between the SP form and MC form of spiropyran moieties inside nanoparticles and thus reversibly switch on and switch off the FRET process. The prepared photoswitchable fluorescent polymer nanoparticles not only show a high load capacity of dyes, controllable amount and ratio of the two dyes, and tunable FRET efficiency but also exhibit higher spectral stability because of covalent linkage between dye molecules and the particle, relatively fast photoresponsibility, and better photoreversibility compared to some previously reported systems.

Label-free optical biosensor based on localized surface plasmon resonance of immobilized gold nanorods

We describe the fabrication and characterization of a localized surface plasmon resonance (LSPR) biosensor that utilizes gold nanorods immobilized as the optical transducer which requires the intensity change at a single wavelength to be monitored as a function of receptor-analyte binding at the nanorod surface. In contrary to free gold nanorods suspended in an aqueous solution with high sensitivity to the longitudinal plasmon wavelength to the surrounding environment, the intensity of the longitudinal plasmon band based on immobilized gold nanorods is more sensitive to changes in the surrounding dielectric properties than the change in the longitudinal plasmon wavelength. Quantitative calculation gives a linear equation between the concentration (X) of the test sample and intensity of LPB (Y) as Y=0.0881+12.9502X and 0.1 pM anti-goat can be detected using this IgG probe in this study. This sensor chip made of immobilized gold nanorods is very stable. The immobilized gold nanorods preserved under 4 degrees C for 1 year yield almost the same extinction spectrum as the original nanorods. This study reveals a reliable and sensitive method to measure the intensity of longitudinal plasmon bands based on the highly stable LSPR substrate. Moreover, the performance is comparable to dynamic SPR measurements in immunoassays and can monitor the receptor-analyte reactions in real time.

Optical and biological sensing capabilities of Au2S/AuAgS coated gold nanorods.

Gold nanorods coated with a multiplex component, namely Au(2)S/AuAgS coated gold nanorods, are produced without precipitation and aggregation among the nanorods. Both the thickness of the shell and size of the core can be readily controlled by this technique allowing one to tune the plasmon resonance of the nanocomposites over a range of several hundred nanometers. These Au(2)S/AuAgS coated gold nanorods exhibit interesting optical properties and are suitable for many biological sensing applications. Functionalization of the Au(2)S/AuAgS coated gold nanorods is achieved by manipulating the affinity between the Au(2)S/AuAgS and thiol compounds. Biomolecules can be covalently attached via the NH(2) bond of the antibodies to the NHS-terminated nanorods. The longitudinal peaks of the Au(2)S/AuAgS coated gold nanorods are extremely sensitive to the refractive index changes induced by target binding, suggesting that they are excellent sensors for target-specific binding events and have the potential to achieve single-molecule sensitivity in microspectroscopy.

Study of the interaction between N-confused porphyrin and bovine serum albumin by fluorescence spectroscopy

The fluorescence and ultraviolet spectroscopy were explored to study the interaction between N-confused porphyrins (NCP) and bovine serum albumin (BSA) under imitated physiological condition. The experimental results indicated that the fluorescence quenching mechanism between BSA and NCP was static quenching procedure at low NCP concentration at 293 and 305 K or a combined quenching (static and dynamic) procedure at higher NCP concentration at 305 K. The binding constants, binding sites and the corresponding thermodynamic parameters ΔH, ΔS, and ΔG were calculated at different temperatures. The comparison of binding potency of the three NCP to BSA showed that the substituting groups in benzene ring could enhance the binding affinity. From the thermodynamic parameters, we concluded that the action force was mainly hydrophobic interaction. The binding distances between NCP and BSA were calculated using Förster non-radiation energy transfer theory. In addition, the effect of NCP on the conformation of BSA was analyzed using synchronous fluorescence spectroscopy.

One-pot fabrication of polymer nanoparticle-based chemosensors for Cu2+ detection in aqueous media

Cupric pollution is a global problem, and the development of stable and sensitive fluorescent probes for cupric ions in the water phase has long been sought. In the present study, we report on the fabrication of core–shell nanoparticle-based fluorescent chemosensors for Cu2+ detection in aqueous media. The core–shell nanoparticle sensor was prepared by a facile one-pot miniemulsion polymerization, in which the fluorescent dye (4-methamino-9-allyl-1,8-naphthalimide, MANI) was covalently incorporated into particle core and the Cu2+ ligand i.e. Vinylbenzylcyclam (VBC), chemically linked onto the surface. The cyclam-functionalized fluorescent polymeric nanoparticles exhibit a high affinity for Cu2+ ions in aqueous media. Upon the addition of Cu2+, the fluorescent emission of the MANI dye in nanoparticles can be quenched on the basis of intraparticle fluorescence resonance energy transfer (FRET) from the dye in the hydrophobic PMMA core to the Cu2+–cyclam complexes on the nanoparticle surface, and the nanoparticle sensor can selectively detect the Cu2+ in water with the detection limit of 500 nM. The observed FRET efficiencies (31.6–73.4%), as well as the distance (r) between MANI (donor) and Cu2+–cyclam complexes (acceptor), were also determined. No interference was observed from other metal ions, making it a highly sensitive and selective Cu2+ probe. Moreover, the nanoparticle-based fluorescent sensor was applicable in a relatively wide pH range (pH 4–10) in water and it exhibited excellent long-term photostability for Cu2+ detection (>45 days) in aqueous media; thus, this approach may provide a new strategy for ratiometric detection of analytes in environmental and biological applications.

Structure, properties, and nature of the pyridine-XY (X, Y=F, Cl, Br) complexes: An ab initio study

Structure and properties (energies, electronic, and thermodynamic properties) of complexes pyridine-XY (X, Y = F, Cl, Br) have been investigated at the MP2/aug-cc-pVDZ level. Two types of geometries (pi-halogen bonded and sigma-halogen bonded) are observed. In contrast with the previous results on similar furan and thiophene complexes, the sigma-halogen bonded structures are more stable and the reasons are discussed. Charge transfer is found to be important in the formation of title system and the possible existing complexes under experimental conditions have been forecasted too. A symmetry-adapted perturbation theory energy decomposition analysis reveals that the pyridine-XY complexes are dominantly inductive in nature.

Enhanced water stability of a microporous acylamide-functionalized metal–organic framework via interpenetration and methyl decoration

A microporous acylamide-functionalized MOF with a 2-fold interpenetrated and methyl decorated framework (HNUST-4) has been designed and synthesized from [Cu2(COO)4] motifs and a C2-symmetric acylamide-linking tetracarboxylate, which exhibits good water stability, permanent porosity as well as high and selective CO2 uptake at ambient temperature.

Study on the interaction between salvianic acid A sodium and bovine serum albumin by spectroscopic methods.

The interaction between salvianic acid A sodium (SAS) and bovine serum albumin (BSA) was investigated using fluorescence and ultraviolet spectroscopy at different temperatures under imitated physiological conditions. The experimental results showed that the fluorescence of BSA was quenched by SAS through a static quenching procedure. The binding constants of SAS with BSA were 2.03, 1.17 and 0.71×10(5) L mol(-1) at 291, 298 and 305 K, respectively. Negative values of ΔG, ΔH, and ΔS indicate that the interaction between SAS and BSA is driven by hydrogen bonds and van der Waals forces. According to Förster non-radiation energy transfer theory, the binding distance between BSA and SAS was calculated to be about 2.92 nm. The effect of SAS on the conformation of BSA was analyzed using synchronous fluorescence spectroscopy. In addition, the effect of some metal ions Cu(2+), Ca(2+), Mg(2+), and Zn(2+) on the binding constant between SAS and BSA was examined.