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ABSTRACT Fluorescent nanoparticles with multiplex distinct emission signatures and high brightness by a single wavelength excitation are substantially needed in multiplex bioassays and imaging. In this study, we synthesized fluorescent polymeric nanoparticles incorporated with three polymerizable organic dyes via a one-pot miniemulsion. By altering the doping ratio of three tandem dyes, the nanoparticles display abundant multiple fluorescence such as blue, cyan, green, orange, pink, red etc., together with distinguishable emission signatures under a single wavelength excitation, which were arising from the effective fluorescence resonance energy transfer (FRET) between the three energy-matched dyes. Meanwhile, a large Stokes shift (up to 250 nm) can be generated by taking place multiple FRET cascade mechanism between donor and acceptor fluorophores in nanoparticles, which also suggests broad applications in biological labeling and imaging. Moreover, these nanoparticles are uniform in size, highly bright, excellently photostable, and shown prominent longterm stability. Overall, the novel multicolor fluorescent polymeric nanoparticles augur well for their potential applications in multiplexed bioanalysis and emitting displays. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41492. [ABSTRACT FROM AUTHOR]

In a one-pot synthesis, 1′-methyl-2,3″-dioxo-5″-aryl-1,2,5a″,7″,8″,9a″-hexahydro-5″H,6″H-dispiro[indole-3,2′-pyrrolidine-3′,2″-pyrano[2,3-d][1,3]thiazolo[3,2-a]pyrimidine]-4′-carboxylic acid methyl ester was prepared via the sequential reaction of 4-aryl-octahydro-pyrano[2,3-d]pyrimidine-2-thione, dimethyl acetylenedicarboxylate (DMAD), and a mixture of isatin and sarcosine. All the novel spiro compounds, in moderate yields, were characterized thoroughly by infrared, NMR, mass spectromentry, and elemental analysis together with x-ray crystallographic analysis. [ABSTRACT FROM PUBLISHER]

Quantum chemical calculations at the MP2 level with the aug-cc-pVTZ basis set were used to investigate the ⋯()n ( = , , and n = 1, 2) complexes. They are connected via hydrogen bond or halogen bond in dimers and together in trimers. Molecular geometries, interaction energies, cooperative energies and atomic charge of dyads and triads have been studied at the Mp2/aug-cc-pVTZ computational level. All studied trimers show cooperativity with the simultaneous presence of a hydrogen and one or two halogen bond. The molecular electrostatic potential has been employed to explore the formation mechanisms of these molecular complexes. The AIM analysis has been performed at the Mp2/aug-cc-pVTZ level to examine the topological characteristics, confirming the coexistence of hydrogen bonds and one or two halogen bond for each complex. The quantum chemical calculations show that the main influencing factors of stabilities for the complexes in the title system are the strength of halogen bond or hydrogen bond and the formation of ringy structure. All studied triads show energetic interplay and the largest favorable cooperative energy is founded in the HF⋯BrCl⋯BrCl-1. The electrostatic potential analysis indicate the stronger electronegativity of the halogen atom is beneficial to form more stable trimers and the AIM analysis make clear that all the complexes are predominantly electrostatic in character. [ABSTRACT FROM AUTHOR]

The of azomethine ylide generated in situ from isatin and sarcosine to 2-arylmethylidene-2,3-dihydro-1 H-pyrrolizin-1-ones afforded novel 1′-methyl-4′-(aryl)-1″ H-dispiro[indole-3,2′-pyrrolidine-3′,2″-pyrrolizine]-1″,2(1 H)-diones in good yields. The structures of all the products were characterized thoroughly by NMR, , mass spectrum, and elemental analysis. [ABSTRACT FROM AUTHOR]

Density functional theory calculations were performed at the B3LYP/6-311++G(d,p) level to systematically explore the geometrical multiplicity and binding strength for the complexes formed by alkaline and alkaline earth metal cations, viz. Li+, Na+, K+, Be2+, Mg2+, and Ca2+ (M n+, hereinafter), with 2-(3′-hydroxy-2′-pyridyl)benzoxazole. A total of 60 initial structures were designed and optimized, of which 51 optimized structures were found, which could be divided into two different types: monodentate complexes and bidentate complexes. In the cation-heteroatom complex, bidentate binding is generally stronger than monodentate binding, and of which the bidentate binding with five-membered ring structure has the strongest interaction. Energy decomposition revealed that the total binding energies mainly come from electrostatic interaction for alkaline metal ion complexes and orbital interaction energy for alkaline earth metal ion complex. In addition, the electron localization function analysis show that only the BeO and BeN bond are covalent character, and others are ionic character. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Abstract: Gold nanorods coated with a multiplex component, namely Au2S/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 Au2S/AuAgS coated gold nanorods exhibit interesting optical properties and are suitable for many biological sensing applications. Functionalization of the Au2S/AuAgS coated gold nanorods is achieved by manipulating the affinity between the Au2S/AuAgS and thiol compounds. Biomolecules can be covalently attached via the NH2 bond of the antibodies to the NHS-terminated nanorods. The longitudinal peaks of the Au2S/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. [Copyright &y& Elsevier]

A non-catalytic condensation of Ni II β-aminonorcorrole with aryl aldehydes is shown to produce a family of pyrromethane dimers that undergo deaminative cyclization to yield pyridine-fused bis(norcorrole)s comprising two antiaromatic macrocycles communicating by an aromatic moiety. The new compounds were characterized by spectroscopic, structural, and electrochemical methods supported by DFT calculations, all of which revealed unexpected antiaromaticity enhancement in the fused system., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The design of effective tools for detecting copper ion (Cu 2+ ) and sulfide anion (S 2- ) is of great importance due to the abnormal level of Cu 2+ and S 2- has been associated with an increase in risk of many diseases. Herein, we report on the fabrication of fluorescence resonance energy transfer (FRET) based fluorescent probe PF (PEI-FITC) for detecting Cu 2+ and S 2- in 100% aqueous media via a facile one-pot method by covalent linking fluorescein isothiocyanate (FITC) with branched-polyethylenimine (b-PEI). PF could selectively coordinate with Cu 2+ among 10 metal ions to form PF-Cu 2+ complex, resulting in fluorescence quenching through FRET mechanism. Furthermore, the in situ generated PF-Cu 2+ complex can be used to selectively detect S 2- based on the displacement approach, resulting in an off-on type sensing. There is no obvious interference from other anions, such as Cl - , NO 3 - , ClO 4 - , SO 4 2- , HCO 3 - , CO 3 2- , Br - , HPO 4 2- , F - and S 2 O 3 2- . In addition, PF was successfully used to determine Cu 2+ and S 2- in human serum and tap water samples. Therefore, the FRET-based probe PF may provide a new method for selective detection of multifarious analysts in biological and environmental applications, and even hold promise for application in more complicated systems., (Copyright © 2017 Elsevier B.V. All rights reserved.)

In this study, amphiphilic diblock copolymers were designed and synthesized via the incorporation of reversible addition-fragmentation chain transfer radical polymerization (RAFT) and a subsequent grafting technique. Subsequently, Hg 2+ -sensitive water-soluble fluorescent polymeric micelles (FNs) were prepared by a reprecipitation strategy. The spectroscopic characteristics demonstrate that the fluorescein isothiocyanate (FITC) was successfully linked into the polymer. Due to the promoted reaction of desulfurization cyclization by Hg 2+ , the fluorescence of fluorescein in FNs was obviously quenched. The as-prepared FNs showed admirable Hg 2+ -sensitivity (detection limit: 54 nM), excellent water-solubility and high selectivity. In addition, FNs were successfully used to determine Hg 2+ in blood serum. We expected that the as-prepared FNs could perform potential applications in imaging, sensing, and bioanalytic chemistry.

The fluorescence and ultraviolet-visible (UV-Vis) spectroscopy were explored to study the interaction between Tropicamide (TA) and bovine serum albumin (BSA) at three different temperatures (292, 301 and 310K) under imitated physiological conditions. The experimental results showed that the fluorescence quenching mechanism between TA and BSA was static quenching procedure. The binding constant (Ka), binding sites (n) were obtained. The corresponding thermodynamic parameters (ΔH, ΔS and ΔG) of the interaction system were calculated at different temperatures. The results revealed that the binding process is spontaneous, hydrogen binds and vander Waals were the main force to stabilize the complex. According to Förster non-radiation energy transfer theory, the binding distance between TA and BSA was calculated to be 4.90 nm. Synchronous fluorescence spectroscopy indicated the conformation of BSA changed in the presence of TA. Furthermore, the effect of some common metal ions (Mg(2+), Ca(2+), Cu(2+), and Ni(2+)) on the binding constants between TA and BSA were examined., (Copyright © 2013 Elsevier B.V. All rights reserved.)

The interaction of carteolol hydrochloride, to 0.2 mol L(-1) urea-induced bovine serum albumin in aqueous solution has been first investigated by fluorescence spectra and ultraviolet-visible (UV-vis) spectra at pH 7.40. The quenching mechanism, binding parameter and sites (n), the binding mode (ΔG, ΔH, and ΔS) as well as the binding distance (r) have been obtained according to the experimental results. We also use the synchronous fluorescence method to study the effect of CTL on the conformation change of urea-induced BSA., (Copyright © 2013 Elsevier B.V. All rights reserved.)

The fluorescence and ultraviolet spectroscopy were explored to study the interaction between Oxymetazoline hydrochloride (OMZH) and mucin under imitated physiological condition. The results demonstrated that the fluorescence quenching mechanism between OMZH and mucin is a combined quenching process. The binding constants (K(a)), binding sites (n) and the corresponding thermodynamic parameters (ΔG, ΔH, and ΔS) of the interaction system were calculated at different temperatures. The hydrogen bonds and van der Waals forces play a major role in the interaction between OMZH and mucin. According to Förster non-radiation energy transfer theory, the binding distance between OMZH and mucin was calculated., (Copyright © 2012 Elsevier B.V. All rights reserved.)

The interaction between thiazolo[2,3-b]pyrimidine (TZPM) analogues and bovine serum albumin (BSA) was investigated by fluorescence spectroscopy and UV-Vis spectroscopy at two different temperatures (299 and 307K) under imitated physiological conditions. The results indicate that both static quenching and dynamic quenching contribute to the fluorescence quenching of BSA by TZPM. The binding constant (K(a)) and binding sites (n) were calculated from the obtained spectra. Based on the Förster non-radiation energy transfer theory, the average binding distance between BSA and TZPM was estimated. The synchronous fluorescence spectra indicate that the conformation of BSA has been changed. The comparison of binding potency of TZPM and BSA suggests that the substituents on the benzene ring enhance the binding affinity of TZPM and BSA. We investigated the possible sub-domains on BSA that bind TZPM by displacement experiments. Furthermore, to explore the effect of molecular structure on the binding, a study on quantitative structure-property relationship (QSPR) was performed, the quantitative relationship equation of R(0), r and K(a) were obtained. We observed that R(0), r and K(a) between BSA and TZPM is connected with the margin of the highest and the lowest occupied orbital energy (ΔE), dipole moment (μ), Molar Volume (V(m)), Mole Mass (M)., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Spiro pyrrolidines, which were proved with diverse and potent biological activities and they were discovered widespread in nature. In this paper, using fluorescence and ultraviolet spectroscopy, we investigated the interactions between novel spiro pyrrolidine (NSP) and bovine serum albumin (BSA) under the imitated physiological condition. The results show that the NSP binds to BSA molecules. Static quenching and non-radiation energy transfer are the main reasons for fluorescence quenching. We calculated the binding constant (K(a)) and binding sites (n) at different temperatures and obtained the binding distance between the tryptophan residue in BSA and the NSP based on the Förster theory of non-radiation energy transfer. In addition, using synchronous fluorescence spectra, we demonstrated conformation changes of BSA caused by NSP. The comparison of binding potency of NSP and BSA suggests that the substituent on the benzene ring influences the binding ability of NSP and BSA., (Copyright © 2012 Elsevier B.V. All rights reserved.)

The interaction between N-confused porphyrins-(4-hydroxycoumarins) diad (NCP-(4-hydroxycoumarins)) and bovine serum albumin (BSA) was studied using fluorescence and ultraviolet spectroscopy at different temperatures under imitated physiological conditions. The experimental results showed that the fluorescence of BSA was quenched by NCP-(4-hydroxycoumarins) through a combined quenching procedure. The binding constants, binding sites and corresponding thermodynamic parameters between NCP-(4-hydroxycoumarins) and BSA at different temperatures were obtained. According to Förster non-radiation energy transfer theory, the binding distance between BSA and NCP-(4-hydroxycoumarins) was calculated to be about 2.1 nm. The effect of NCP-(4-hydroxycoumarins) 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 Ni(2+) on the binding constant between NCP-(4-hydroxycoumarins) and BSA was examined., (Copyright © 2012 Elsevier B.V. All rights reserved.)

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.