Resculpting carbon dots via electrochemical etching.

Substantial efforts are directed into exploring the structure-properties relationships of photoluminescent Carbon dots (C-dots). This study unravels a resculpting mechanism in C-dots that is triggered by electrochemical etching and proceeds via extensive surface oxidation and carbon-carbon breakage. The process results in the gradual shrinkage of the nanoparticles and can enhance the quantum yield by more than half order of magnitude compared to the untreated analogues.

Carbon Dots/Iron Oxide Nanoparticles with Tuneable Composition and Properties.

We present a simple strategy to generate a family of carbon dots/iron oxide nanoparticles (C/Fe-NPs) that relies on the thermal decomposition of iron (III) acetylacetonate in the presence of a highly fluorescent carbon-rich precursor (derived via thermal treatment of ethanolamine and citric acid at 180 °C), while polyethylene glycol serves as the passivation agent. By varying the molar ratio of the reactants, a series of C/Fe-NPs have been synthesized with tuneable elemental composition in terms of C, H, O, N and Fe. The quantum yield is enhanced from 6 to 9% as the carbon content increases from 27 to 36 wt%, while the room temperature saturation magnetization is improved from 4.

A rich gallery of carbon dots based photoluminescent suspensions and powders derived by citric acid/urea.

In this study we demonstrate simple guidelines to generate a diverse range of fluorescent materials in both liquid and solid state by focusing on the most popular C-dots precursors, i.e. the binary systems of citric acid and urea.

Layer by Layer Antimicrobial Coatings Based on Nafion, Lysozyme, and Chitosan.

The study focuses on the development of a new family of layer-by-layer coatings comprising Nafion, lysozyme and chitosan to address challenges related to microbial contamination. Circular dichroism was employed to gain insights on the interactions of the building blocks at the molecular level. Quartz crystal microbalance tests were used to monitor in real time the build-up of multilayer coatings, while atomic force microscopy, contact angle and surface zeta potential measurements were performed to assess the surface characteristics of the multilayer assemblies.

Formation mechanism of carbogenic nanoparticles with dual photoluminescence emission.

We present a systematic investigation of the formation mechanism of carbogenic nanoparticles (CNPs), otherwise referred to as C-dots, by following the pyrolysis of citric acid (CA)-ethanolamine (EA) precursor at different temperatures. Pyrolysis at 180 °C leads to a CNP molecular precursor with a strongly intense photoluminescence (PL) spectrum and high quantum yield formed by dehydration of CA-EA. At higher temperatures (230 °C) a carbogenic core starts forming and the PL is due to the presence of both molecular fluorophores and the carbogenic core.

Interactions of an anionic surfactant with poly(oxyalkylene) copolymers in aqueous solution.

The interactions of sodium dodecyl sulfate (SDS) with poly(ethylene oxide)/poly(alkylene oxide) (E/A) block copolymers are explored in this study. With respect to the specific compositional characteristics of the copolymer, introduction of SDS can induce fundamentally different effects to the self-assembly behavior of E/A copolymer solutions. In the case of the E(18)B(10)-SDS system (E = poly(ethylene oxide) and B = poly(butylene oxide)) development of large surfactant-polymer aggregates was observed.

Orientational ordering in the nematic phase of a polyethylene glycol-peptide conjugate in aqueous solution.

The orientational ordering of the nematic phase of a polyethylene glycol (PEG)-peptide block copolymer in aqueous solution is probed by small-angle neutron scattering (SANS), with the sample subjected to steady shear in a Couette cell. The PEG-peptide conjugate forms fibrils that behave as semiflexible rodlike chains. The orientational order parameters P2 and P4 are obtained by modeling the data using a series expansion approach to the form factor of uniform cylinders.

Nematic and columnar ordering of a PEG-peptide conjugate in aqueous solution.

The self-assembly in aqueous solution of a PEG-peptide conjugate is studied by spectroscopy, electron microscopy, rheology and small-angle X-ray and neutron scattering (SAXS and SANS). The peptide fragment, FFKLVFF is based on fragment KLVFF of the amyloid beta-peptide, Abeta(16-20), extended by two hydrophobic phenylalanine units. This is conjugated to PEG which confers water solubility and leads to distinct self-assembled structures.

Effect of PEG crystallization on the self-assembly of PEG/peptide copolymers containing amyloid peptide fragments.

The effect of poly(ethylene glycol) PEG crystallization on beta-sheet fibril formation is studied for a series of three peptide/PEG conjugates containing fragments modified from the amyloid beta peptide, specifically KLVFF, FFKLVFF, and AAKLVFF. These are conjugated to PEG with M n = 3300 g mol (-1). It is found, via small-angle X-ray scattering, X-ray diffraction, atomic force microscopy, and polarized optical microscopy, that PEG crystallinity in dried samples can disturb fibrillization, in particular cross-beta amyloid structure formation, for the conjugate containing the weak fibrillizer KLVFF, whereas this is retained for the conjugates containing the stronger fibrillizers AAKLVFF and FFKLVFF.

Interactions of bovine serum albumin with ethylene oxide/butylene oxide copolymers in aqueous solution.

The interactions of bovine serum albumin (BSA) with three ethylene oxide/butylene oxide (E/B) copolymers having different block lengths and varying molecular architectures is examined in this study in aqueous solutions. Dynamic light scattering (DLS) indicates the absence of BSA-polymer binding in micellar systems of copolymers with lengthy hydrophilic blocks. On the contrary, stable protein-polymer aggregates were observed in the case of E 18B 10 block copolymer.

Self-assembly and hydrogelation of an amyloid peptide fragment.

The self-assembly of a fragment of the amyloid beta peptide that has been shown to be critical in amyloid fibrillization has been studied in aqueous solution. There are conflicting reports in the literature on the fibrillization of Abeta (16-20), i.e.

Polymer-surfactant vesicular complexes in aqueous medium.

The introduction of ionic single-tailed surfactants to aqueous solutions of EO(18)BO(10) [EO = poly(ethylene oxide), BO = poly(1,2-butylene oxide), subscripts denote the number of repeating units] leads to the formation of vesicles, as probed by laser scanning confocal microscopy. Dynamic light scattering showed that the dimensions of these aggregates at early stages of development do not depend on the sign of the surfactant head group charge. Small-angle X-ray scattering (SAXS) analysis indicated the coexistence of smaller micelles of different sizes and varying polymer content in solution.

Structural study of BSA/poly(ethylene glycol) lipid conjugate complexes.

In this work we report the structural characteristics of bovine serum albumin/poly(ethylene glycol) lipid conjugate (BSA/PEG(2000)-PE) complexes under physiological conditions (37 degrees C and pH 7.4) for particular fractions of BSA to PEG-lipid concentration, c(BSA)/c(PEG)(2000)-PE. Ultraviolet fluorescence spectroscopy (UV) results shown that PEG(2000)-PE is associated to BSA, leading to protein unfolding for fixed c(BSA) = 0.