Synthesis of gold nanoparticles using poly(ethyleneglycol)-b-poly(N,N-diethylaminoethylmethacrylate) as nanoreactors

Exploring the role of Muscovite in poly(alkyl methacrylate)-based ternary nanocomposite cryogels with selective functional groups: formation via cryogelling with the aid of inorganic clay

Easy fabrication of inorganic clay muscovite (MUS) embedded poly(2-acrylamido-2-methyl-1-propane sulfonic acid-co-diethylaminoethyl methacrylate-co-hydroxyethyl methacrylate) (PADH) nanocomposite cryogels with dual temperature/pH dependent catalytic potential was reported. Nanocomposite cryogels were fabricated by a method involving cryogelation and free radical crosslinking of aqueous systems containing MUS ranging from 0% to 1.50% (w/v). The changes in the properties of polybasic PADH networks were investigated to explain how the network parameters and gel properties were affected by the addition of clay, with the formation of a single terpolymer-MUS structure. The potential of the addition of different amounts of MUS to strengthen the prepared terpolymer matrix was investigated by uniaxial compression tests. By lowering the polymerization temperature or increasing the MUS content, the PADH/MUS nanocomposite cryogels became more elastic and compressible with stronger entanglement of terpolymer chains between the clay layers. With the addition of 1.50% (w/v) MUS, the swelling capacity was reduced by 50%, resulting in a two-fold increase in compression elasticity. The nanocomposite gels showed a strong pH-dependence, and when the pH of the swelling medium decreased from 9.8 to 2.1, there was a significant increase in the degree of swelling with increasing protonation of tertiary amine groups. Under an acidic environment, the swelling capacity of the nanocomposite gel containing 1.10% (w/v) MUS increased by 49.5%. In temperature dependent swelling between 15 and 75 °C, all ternary PADH/MUS-Ngels showed a tendency to swell at low and high swelling temperatures, by the predominance of DEAEM units at low temperatures and HEMA monomers at high temperatures, respectively. As the temperature was increased to 55 °C, the swelling decreased and reached a minimum, and then the nanocomposite gels tended to swell again. The obtained results provide an insight into the effect of MUS addition on the properties of poly(alkyl methacrylate)-based ternary nanocomposite gels and demonstrate a simple and efficient way to produce multiple response systems with enhanced elasticity.

Synthesis by spray pyrolysis of gold nano species confined in iron oxide nanospheres effective in the reduction of 4-nitrophenol to 4-aminophenol

The highly effective Au/Fe₂O₃-@Au/Fe₂O₃nanoreactors for the 4-nitrophenol (4-NP) reduction are successfully obtained by one-pot synthesis using the spray pyrolysis (SP) technique. The Au/Fe₂O₃-@Au/Fe₂O₃nanoreactors manifest superior catalytic activity in the reduction of 4-NP in the presence of sodium borohydride (NaBH₄) compared to gold-iron oxide nanoreactors prepared via a colloidal approach. The negative effect of the reaction product accumulation, the 4-aminophenol (4-AP), on the catalytic reduction of 4-NP over Au/Fe₂O₃-@Au/Fe₂O₃is examined by a direct pre-injection of 4-AP to the reaction media. To the best of our knowledge, it is the first experimental evidence of gold active sites blocking by 4-AP. All obtained samples are characterized by the yolk-shell spherical hollow structure mainly consisted of two embedded hollow nanospheres. The reduction of iron oxide precursor concentration diminishes the diameter of final iron oxide nanospheres. According to STEM-EDS analysis and STEM, Au nano species are uniformly dispersed on both iron oxide nanospheres. The SP technique presently used to synthesize Au/Fe₂O₃-@Au/Fe₂O₃nanoreactors manifests high potential for the one-pot fabrication of a large variety of nanoreactors with various active materials applied as heterogeneous catalysts in numerous catalytic processes.

Nanoengineering of Gold Nanoparticles: Green Synthesis, Characterization, and Applications

The fundamental aspects of the manufacturing of gold nanoparticles (AuNPs) are discussed in this review. In particular, attention is devoted to the development of a simple and versatile method for the preparation of these nanoparticles. Eco-friendly synthetic routes, such as wet chemistry and biosynthesis with the aid of polymers, are of particular interest. Polymers can act as reducing and/or capping agents, or as soft templates leading to hybrid nanomaterials. This methodology allows control of the synthesis and stability of nanomaterials with novel properties. Thus, this review focus on a fundamental study of AuNPs properties and different techniques to characterize them, e.g., Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM), UV-Visible spectroscopy, Dynamic Light Scattering (DLS), X-Ray Diffraction (XRD), X-Ray Photoelectron Spectroscopy, Small-angle X-Ray Scattering (SAXS), and rheology. Recently, AuNPs obtained by “green” synthesis have been applied in catalysis, in medicine, and as antibacterials, sensors, among others.

Dual Responsive Polymersomes for Gold Nanorod and Doxorubicin Encapsulation: Nanomaterials with Potential Use as Smart Drug Delivery Systems

In the present study, poly(ethylene glycol)-b-poly(N,N-diethylaminoethyl methacrylate) (PEG-b-PDEAEM) amphiphilic block copolymers were synthetized by reversible addition-fragmentation chain transfer (RAFT) polymerization using two different macro chain transfer agents containing PEG of 2000 and 5000 g/mol and varying the length of the PDEAEM segment. From the obtained block copolymers, polymersome type nanometric aggregates were obtained by two different techniques. By direct dispersion, particle diameters around 200 nm were obtained, while by solvent exchange using THF and water, the obtained diameters were around 100 nm. These block copolymers were used to encapsulate gold nanorods and doxorubicin (DOX) with good efficiencies to obtain nanomaterials with potential use as dual stimuli-sensitive drug delivery systems for combined anticancer therapies. Drug delivery studies showed that the release rate of DOX was accelerated when the pH was lowered from 7.4 to 5.8 and also when the systems were irradiated with a NIR laser at pH 7.4. The combination of lower pH and near infrared (NIR) irradiation resulted in higher drug release only in the case of polymersomes with lower molecular weight PEG.