Engineering surface patterns on nanoparticles: New insights on nano-bio interactions

The surface properties of nanoparticles affect their fates in biological systems. Based on nanotechnology and methodology, pioneering works have explored the effects of chemical surface patterns on the behavior of...

Ultrasonic De-cross-linking of the pH- and Magneto-Responsive PHEMA/PMMA Microgel to Janus Nanoparticles: A New Synthesis Based on "Grafting from"/"Grafting to" Polymerization

Stimuli-responsive Janus nanoparticles (NPs) with a two-facial structure have been used widely in biomedical applications. Among several methods to prepare these NPs, surface-initiated atom transfer radical polymerization (SI-ATRP) has received much attention due to the precise deposition of polymers on the surface of the substrate. In this study, Janus nanoparticles with asymmetric surface chemistry were prepared through a masking method in three steps involving the covalent deposition of super paramagnetic iron oxide nanoparticles (SPIONs) on the cross-linked substrate based on methotrexate (MTX)-grafted poly(2-hydroxyethyl methacrylate) (CPM), surface functionalization of unreacted sites of immobilized SPIONs with 2-bromoisobutyryl bromide (BIBB) in order to prepare the macro-initiator (Br-Fe3O4-CPM), growing poly(methyl methacrylate) (PMMA) on the surface of the macro-initiator through the SI-ATRP method. Optical microscopy was utilized to monitor the successful modification of SPIONs. Poly(methyl methacrylate)-iron oxide-poly(2-hydroxyethyl methacrylate) (PMMA-Fe3O4-PHEMA) microgel was exposed to optimum ultrasound (US) waves to prepare the PMMA-Fe3O4-PHEMA nanoparticle. Transmission electron microscopy (TEM) was used to confirm the precise deposition of polymers and the Janus structure. The MTX release of US-synthesized Janus NPs was studied in PBS at pH values of 7.4 and 5.8. The release data were analyzed using the Excel add-in DDSolver program to evaluate the kinetics of the drug release process from the nanocarrier under different pH values.

Anisotropic Nano-/Microparticles from Diversified Copolymers by Solvent-Mediated Self-Assembly

Effective synthesis of anisotropic nano-/microparticles (APs) by the copolymers is of great significance in nanomaterials and nanotechnology. However, achieving regulation of the morphology, composition, property, and particle size of anisotropic nano-/microparticles (APs) with diversified copolymers is difficult due to complex mechanism and formation conditions. In this work, a versatile one-pot solvent-mediated self-assembly (SmSa) strategy had been proposed for the facile one-pot synthesis of shape-tunable anisotropic nano-/microparticles (StAPs). In addition, the formation mechanism of StAPs was determined through numerous characterization methods related to morphology and element distribution. The results revealed that the anisotropic architectures of StAPs were closely related to the nature of poly(methylacrylic acid-methyl methacrylate-butyl acrylate) (L₁) and poly(butyl acrylate-styrene) (L₂) polymer chains imparted by polymer blocks of different domains. Therefore, the ordered assembly of the rigid and hydrophobic L₂ polymer chains in micelles consisting of the flexible and amphiphilic L₁ and solvent could be successfully carried out under the mediation of increasing solvent polarity and the strong adsorption of poly(vinylpyrrolidone) for L₂. Furthermore, the developed versatile SmSa strategy and the obtained StAPs play an essential role in the development of nanoscience and nanotechnology. Particularly given its adjustable emulsifying properties at different pH values, as well as numerous sites for further modification by fluorescent or other components, it can be employed to synthesize a wide range of functional materials.

Long-subchain Janus-dendritic copolymers from locally confined click reaction and generation-dependent micro-phase separation

Long-subchain Janus-dendritic copolymers composed of PSt and PtBA half-dendrons, up to the third generation, were prepared under alternating chemical and local confinement. All the Janus-dendritic copolymers exhibited generation-dependent microphase separation.

Design, synthesis and thermotropic self-organization of dendronized polystyrenes with different length alkyl tails

A reentrant phase is observed for the first time in dendronized polystyrenes with high molecular weight through regulating the length of tail chains.