The Emerging Use of Quantum Dots in Analysis

Abstract

The optical properties of quantum dots (QDs) have made them attractive materials in diverse fields of application. Since water‐soluble derivatives were obtained, quantum dots have attracted intensive research interest in sensing, diagnosis, imaging, and optical tracking. The analytes that have been targeted span ions, small chemical molecules, proteins, nucleic acids, and cells. The fluorescence of functionalized QDs can be quenched, enhanced, or even ‘switch’ on and off in different cases. However, the mechanisms behind these various responses are not yet all fully understood. This review gives an overview of the emerging use of QDs in analysis. Typical examples, in particular in relation to the discussion on mechanisms are highlighted.     

A Gold Nanoparticles–Enhanced Carbon Nanotubes Electrochemical Chiral Sensor

The field of enantioselective recognition directly using inherently chiral single‐walled carbon nanotubes (cSWCNTs) still remains unexplored. Herein, the insertion of size‐controlled gold nanoparticles (GNPs) to cSWCNTs brings about superior conductivity, high stability, and excellent electrocatalytic ability, thus an enhanced sensitivity for chiral sensing. The practicability of the GNPs/cSWCNTs based electrochemical sensor was validated by chirally recognizing 3,4‐dihydroxyphenylalanine and tyrosine as model molecules.     

Relation between structure and enthalpy for stacking interactions of aromatic molecules

An approximately linear correlation has been found between the enthalpy of complexation and the area of overlap of the chromophores using published structural and thermodynamical data on the self- and hetero-association of aromatic molecules measured under similar solution conditions. This finding is consistent with the assumption that short-range van-der-Waals forces dominate over other contributions to the enthalpy of stacking of aromatic molecules. It provides a ‘model-independent’ approach for a priori estimation of the enthalpy of aromatic–aromatic stacking interactions from knowledge of the structural properties or vice versa.     

Nonexistence of global solutions to new ordinary differential inequality and applications to nonlineardispersive equations

A new ordinary differential inequality without global solutions is proposed. Comparison with similar differential inequalities in the well‐known concavity method is performed. As an application, finite time blow up of the solutions to nonlinear Klein–Gordon equation and generalized Boussinesq equation is proven. The initial energy is arbitrary high positive. The structural conditions on the initial data generalize the assumptions used in the literature for the time being. Copyright © 2015 John Wiley & Sons, Ltd.     

Resonance Energy Transfer in a Genetically Engineered Polypeptide Results in Unanticipated Fluorescence Intensity

The fluorescence intensity of a C-terminal acceptor chromophore, N-(7-dimethylamino-4-methyl coumarin (DACM), increased proportionally with 280 nm irradiation of an increasing number of donor tryptophan residues located on a β-sheet forming polypeptide. The fluorescence intensity of the acceptor chromophore increased even as the length of the β-sheet edge approached 256 Å, well beyond the Förster radius for the tryptophan–acceptor chromophore pair. The folding of the peptides under investigation was verified by circular dichroism (CD) and deep UV resonance Raman experiments. Control experiments showed that the enhancement of DACM fluorescence occurred concomitantly with peptide folding. In other control experiments, the DACM fluorescence intensity of the solutions of tryptophan and DACM did not show any enhancement of DACM fluorescence with increasing tryptophan concentrations. Formation of fibrillar aggregates of the substrate peptides prepared for the fluorescence studies was undetectable by thioflavin T (ThT) fluorescence.     

Bifunctional coordination polymers as efficient catalysts for carbon dioxide conversion

The multidentate ligand H₂ L upon complexation with Zn (II) and Cd (II) provide a one‐dimensional polymeric networks. These coordination polymers (CPs) CP‐1 and CP‐2 containing Zn (II) and Cd (II) metals respectively are well characterized. The single crystal structural analysis confirms the formation of one‐dimensional coordination polymer with zigzag fashion in CP‐1 and ladder chain CP‐2 . Both the CPs are applied as catalysts to synthesize various cyclic carbonates from epoxides and carbon dioxide. The catalysts are giving better conversion under solvent‐free and additive‐free condition using 10 bar CO₂ and 100 °C as optimized pressure and temperature. The detailed kinetic experiments suggesting the first order kinetics, the energy of activation (Ea) is calculated for this catalytic conversion.     

Generalizing Rosenbluth's Algorithm to Include Along‐the‐Chain Intramolecular Energies

We incorporate the Boltzmann factors for inter‐monomer bending energy into the monomer growth direction choice in Rosenbluth's algorithm to model chains of arbitrary nearest‐neighbor rigidity. This allows for the consideration of compact (bent state lower in energy), free (straight and bent state equal in energy), or extended chains (bent state higher). We validate against, and compare to, various other results, showing very good agreement with known results for short chains and demonstrate the ability to model chains up to 500 segments long, far beyond the length at which the normal Rosenbluth method becomes unstable for reasonable nonzero bending energies. This approach is easily generalizable both to other energies determinable during chain growth, for example, polymers composed of more than one type of monomer with differing monomer interaction energies, as well as to other chain production algorithms. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 1684–1691