Functional Elastomeric Copolymer Membranes Designed by Nanoarchitectonics Approach for Methylene Blue Removal

Weak Polyelectrolytes as Nanoarchitectonic Design Tools for Functional Materials: A Review of Recent Achievements

The ionization degree, charge density, and conformation of weak polyelectrolytes can be adjusted through adjusting the pH and ionic strength stimuli. Such polymers thus offer a range of reversible interactions, including electrostatic complexation, H-bonding, and hydrophobic interactions, which position weak polyelectrolytes as key nano-units for the design of dynamic systems with precise structures, compositions, and responses to stimuli. The purpose of this review article is to discuss recent examples of nanoarchitectonic systems and applications that use weak polyelectrolytes as smart components. Surface platforms (electrodeposited films, brushes), multilayers (coatings and capsules), processed polyelectrolyte complexes (gels and membranes), and pharmaceutical vectors from both synthetic or natural-type weak polyelectrolytes are discussed. Finally, the increasing significance of block copolymers with weak polyion blocks is discussed with respect to the design of nanovectors by micellization and film/membrane nanopatterning via phase separation.

Oligomer Sensor Nanoarchitectonics for “Turn-On” Fluorescence Detection of Cholesterol at the Nanomolar Level

Sensitive and rapid monitoring of cholesterol levels in the human body are highly desirable as they are directly related to the diagnosis of cardiovascular diseases. By using the nanoarchitectonic approach, a novel fluorescent conjugated oligofluorene (OFP-CD) functionalized with β-cyclodextrin (β-CD) was assembled for “Turn-On” fluorescence sensing of cholesterol. The appended β-CD units in OFP-CD enabled the forming of host-guest complexes with dabsyl chloride moieties in water, resulting in fluorescence quenching of the oligofluorene through intermolecular energy transfer. In the presence of cholesterol molecules, a more favorable host-guest complex with stoichiometry 1 cholesterol: 2 β-CD units was formed, replacing dabsyl chloride in β-CD’s cavities. This process resulted in fluorescence recovery of OFP-CD, owing to disruption of energy transfer. The potential of this nanoarchitectonic system for “Turn-On” sensing of cholesterol was extensively studied by fluorescence spectroscopy. The high selectivity of the sensor for cholesterol was demonstrated using biologically relevant interfering compounds, such as carbohydrates, amino acids, metal ions, and anions. The detection limit (LOD value) was as low as 68 nM, affirming the high sensitivity of the current system.

Bio-interactive nanoarchitectonics with two-dimensional materials and environments

Like the proposal of nanotechnology by Richard Feynman, the nanoarchitectonics concept was initially proposed by Masakazu Aono. The nanoarchitectonics strategy conceptually fuses nanotechnology with other research fields including organic chemistry, supramolecular chemistry, micro/nanofabrication, materials science, and bio-related sciences, and aims to produce functional materials from nanoscale components. In this review article, bio-interactive nanoarchitectonics and two-dimensional materials and environments are discussed as a selected topic. The account gives general examples of nanoarchitectonics of two-dimensional materials for energy storage, catalysis, and biomedical applications, followed by explanations of bio-related applications with two-dimensional materials such as two-dimensional biomimetic nanosheets, fullerene nanosheets, and two-dimensional assemblies of one-dimensional fullerene nanowhiskers (FNWs). The discussion on bio-interactive nanoarchitectonics in two-dimensional environments further extends to liquid-liquid interfaces such as fluorocarbon-medium interfaces and viscous liquid interfaces as new frontiers of two-dimensional environments for bio-related applications. Controlling differentiation of stem cells at fluidic liquid interfaces is also discussed. Finally, a conclusive section briefly summarizes features of bio-interactive nanoarchitectonics with two-dimensional materials and environments and discusses possible future perspectives.

Removal of Organic Dyes from Water and Wastewater Using Magnetic Ferrite-Based Titanium Oxide and Zinc Oxide Nanocomposites: A Review

Heterogeneous photocatalysis using titanium dioxide (TiO2) and zinc oxide (ZnO) has been widely studied in various applications, including organic pollutant remediation in aqueous systems. The popularity of these materials is based on their high photocatalytic activity, strong photosensitivity, and relatively low cost. However, their commercial application has been limited by their wide bandgaps, inability to absorb visible light, fast electron/hole recombination, and limited recyclability since the nanomaterial is difficult to recover. Researchers have developed several strategies to overcome these limitations. Chief amongst these is the coupling of different semi-conductor materials to produce heterojunction nanocomposite materials, which are both visible-light-active and easily recoverable. This review focuses on the advances made in the development of magnetic ferrite-based titanium oxide and zinc oxide nanocomposites. The physical and magnetic properties of the most widely used ferrite compounds are discussed. The spinel structured material had superior catalytic and magnetic performance when coupled to TiO2 and ZnO. An assessment of the range of synthesis methods is also presented. A comprehensive review of the photocatalytic degradation of various priority organic pollutants using the ferrite-based nanocomposites revealed that degradation efficiency and magnetic recovery potential are dependent on factors such as the chemical composition of the heterojunction material, synthesis method, irradiation source, and structure of pollutant. It should be noted that very few studies have gone beyond the degradation efficiency studies. Very little information is available on the extent of mineralization and the subsequent formation of intermediate compounds when these composite catalysts are used. Additionally, potential degradation mechanisms have not been adequately reported.