First Successful Post‐Synthetic Self‐Assembly of Polyaniline with Poly(N‐vinylpyrrolidone) into Aqueous Nanocolloids

Summary: Polyaniline (PANI) is successfully self‐assembled with poly(N‐vinylpyrrolidone) (PVP) into aqueous nanocolloids. The typical morphology of the colloids is studied by atomic force microscopy (AFM), which reveals spherical nanoparticles with a diameter of 80–150 nm. A possible mechanism for such a post‐synthetic self‐assembly process is proposed.

AFM micrograph of PANI aqueous nanocolloids stabilized by PVP via a novel post‐synthetic self‐assembly method.     

Multifunctional Surface Modification: Facile and Flexible Reactivity toward a Precisely Controlled Biointerface

A multicomponent functional polymer is synthesized to support specific reactivity for successful conjugation with the vast array of functionality present in biological systems and the flexibility to conjugate biomolecules without requiring additional modification to install a terminal functional group. The multifunctional surface is realized using a novel coating composed of distinct N‐hydroxysuccinimide (NHS) ester and benzoyl functionalities, which can provide accessibility to both the NHS ester‐amine coupling reaction and the photochemically induced benzophenone crosslinking reaction, respectively. In addition, the multifunctional polymer is fabricated and transformed to form nanoscale colloids through the solvent displacement of a water/DMF system due to solubility characteristics of the resulting polymer with high polarity. A facile and efficient fabrication approach using the multifunctional nanocolloid is thus demonstrated to create a drug carrier by installing paclitaxel and folic acid for targeted cancer therapy.

     

Mechanism of pulse laser interaction with colloidal nanoparticles

The laser is a very powerful and very useful instrument in modern nanoscience and nanotechnology. The knowledge of the interaction mechanism of the laser beam with nanoparticles is needed to control the laser processing of different nano‐objects. It was shown that the particle heating–melting–evaporation model can be successfully applied for many phenomena arising when colloidal nanoparticle interact with pulsed laser beams. The general approach of this model is discussed in detail. The two main components of the model, light absorption by particles, and the thermodynamics of phase transitions in particulate material are considered. Special attention is devoted to the correct estimation of the possible heat losses. The way in which the phase diagrams, where the different phase conditions of particle material are presented in laser fluence−particle diameter coordinates, were produced is demonstrated. It is shown how this model can be applied for understanding the mechanism of such complicated processes as particle‐size reduction and submicrometer spherical particle growth, as well as other processes that occur when colloidal particles are irradiated by a pulsed laser.     

A Cationic Water‐Soluble Poly(p‐phenylenevinylene) Derivative: Highly Sensitive Biosensor for Iron‐Sulfur Protein Detection

Summary: A new water‐soluble cationic ammonium‐functionalized poly(p‐phenylenevinylene) (PPV‐NEtMe) was successfully synthesized and exhibited high sensitivity (K_sv = 6.9 × 10⁷ M ⁻¹) on rubredoxin, a type of anionic iron‐sulfur (Fe‐S) proteins. Further investigation showed that the biosensitivity of the cationic conjugated polymer is strongly dependent on the nature of the buffer solution and the concentration of the conjugated polymer used in the analyses.

The schematic diagram of anionic rubredoxin detected by PPV‐NEtMe.     

Self‐assembly of silver nanocolloids in the Langmuir–Blodgett Film of stearic acid: Evidence of an efficient SERS sensing platform

Highly sensitive surface‐enhanced Raman scattering active substrate obtained by self‐assembly of silver nanocolloids (AgNCs) in the bilayer Langmuir–Blodgett (LB) film of stearic acid (SA) has been reported. Rhodamine 6G (R6G) has been used as the probe molecule to test the efficacy of the as prepared substrate. Gigantic enhancement factors ~10¹² orders of magnitude have been estimated from the surface‐enhanced resonance Raman scattering [SER(R) S] spectrum of R6G, which proves that the as prepared substrate is superior or comparable with silver nanoparticle as dried AgNC solutions on microscopic slides. The optical properties of the as prepared substrates have been envisaged by ultraviolet‐visible absorption spectra, while their morphological features are mapped through field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) images. A correlation has been drawn between the SER(R) S efficacy and the corresponding FESEM and AFM images of the as prepared substrates. Electric field distributions around the aggregated AgNCs have been estimated with the aid of three‐dimensional finite difference time domain simulation studies. Localized surface plasmon coupling between the nanoaggregated geometries may be altered by lifting the LB film of SA at various surface pressures. Copyright © 2015 John Wiley & Sons, Ltd.     

Surface‐enhanced Raman scattering of pyridine‐functionalized multi‐walled carbon nanotubes

Carbon nanotubes (CNTs) have attracted great attention for their potential use in many applications because of their intrinsic properties. The importance other than the impact of the application of CNT‐embedded membranes in the area of water technology development is immense. In this context, the identification and quantification of CNTs in aqueous resources during relevant water purification processes can be proven of high significance. Surface‐enhanced Raman scattering (SERS) potentially has the sensitivity required for trace analysis and has been previously used for CNT identification on solid substrates. A thorough study for the identification and quantification of small concentrations of multi‐walled CNTs (MWCNTs) in water suspensions via SERS has been performed. The functionalization of MWCNTs with pyridine groups seems to favor the surface enhancement of relevant Raman signal. This study constitutes the first step of a work in progress for the characterization of CNTs at quite low concentration range by SERS in any water suspension. It is based on an ex ante functionalization of the CNTs by pyridine, demonstrating the potential of the method. Our long‐term aim is its general application built, however, in an ex post relevant functionalization of the CNTs in any aqueous solution. Copyright © 2014 John Wiley & Sons, Ltd.