Self-propelled micro/nanobots: A new insight into precisely targeting cancerous cells through intelligent and deep cancer penetration

Cancer overlooks are globally one of the most dangerous and life-threatening tribulations. While significant advances have been made in the targeted delivery of anti-cancer medications over the last few years, several challenges, such as low efficacy and strong toxic effects, remain to be addressed. Micro/nanomotors have been thoroughly studied for both effective cancer detection and treatment, as demonstrated by significant advancements in the architecture of smart and functional micro/nanomotor biomedical systems. Able to self-propelled within fluid media, micro/nanomotors have attractive vehicles to maximize the efficacy of tumor delivery. Here, we present the current developments in the delivery, detection, and imaging-guided treatment of micro/nanomotors in the clinical field, including cancer-related specific targeted drug delivery, and then discuss the barriers and difficulties encountered by micro/nanomotors throughout the medical process. Furthermore, this paper addresses the potential growth of micro/nanomotors for medical applications, and sets out the current drawbacks and future research directions for more advancement.

Supramolecular tuning of thioflavin-T aggregation hosted by polystyrene sulfonate

Tunable and controllable emission is an extremely desirable feature for advanced functional materials that finds usage in optoelectronic utilization, fluorescence probing/sensing, drug-delivery monitoring, etc. In the present contribution, we have employed a macrocyclic host molecule, sulfobutyl ether-β-cyclodextrin (SBE-β-CD), as a tuning agent for an intensely emissive aggregate assembly of a molecular rotor dye, thioflavin-T (ThT), in the presence of an anionic polyelectrolyte, polystyrene sulfonate (PSS). The macrocyclic host breaks the PSS templated ThT aggregates and leads to encapsulation of released ThT molecules, tailoring the emission response of the system in terms of intensity and wavelength. Utilizing the established selectivity of the cyclodextrin-adamantane system, reverse control of this tunable emission has been further achieved. The controllable fluorescence system has been extensively investigated using ground-state absorption, steady-state and time-resolved emission spectroscopy. This kind of supramolecular tailoring of self-assembled aggregate emission has enormous potential in the field of fluorescence sensors and probes, and imaging and tracking in biological systems.

Supramolecular Control on the Optical Properties of a Dye-Polyelectrolyte Assembly

Control of fluorescent molecular assemblies is an exciting area of research with large potential for various important applications, such as, fluorescence sensing/probing, cell imaging and monitoring drug-delivery. In the present contribution, we have demonstrated control on the extent of aggregation of a dye-polyelectrolyte assembly using a macrocyclic host molecule, sulfobutylether-β-cyclodextrin (SBE-β-CD). Initially, a cationic molecular rotor based organic dye, Auramine-O (AuO), undergoes aggregation in the presence of an anionic polyelectrolyte, polystyrene sulfonate (PSS), and displays a broad intense new emission band along with large variation in its absorption features and excited-state lifetime. A manipulation of the monomer-aggregate equilibrium of the dye-polyelectrolyte assembly has been achieved by introducing a cyclodextrin based supramolecular host, SBE-β-CD, which leads to relocation of AuO molecules from polyelectrolyte (PSS) to supramolecular host cavity, owing to the formation of a host-guest complex between AuO and SBE-β-CD. A reversible control on this manipulation of monomer-aggregate equilibrium is further achieved by introducing a competitive guest for the host cavity i. e., 1-Adamantanol. Thus, we have demonstrated an interesting control on the dye-polyelectrolyte aggregate assembly using a supramolecular host molecule which open up exciting possibilities to construct responsive materials using a repertoire of various host-specific guest molecules.

Poly(2-oxazoline)- and Poly(2-oxazine)-Based Self-Assemblies, Polyplexes, and Drug Nanoformulations-An Update

For many decades, poly(2-oxazoline)s and poly(2-oxazine)s, two closely related families of polymers, have led the life of a rather obscure research topic with only a few research groups world-wide working with them. This has changed in the last five to ten years, presumably triggered significantly by very promising clinical trials of the first poly(2-oxazoline)-based drug conjugate. The huge chemical and structural toolbox poly(2-oxazoline)s and poly(2-oxazine)s has been extended very significantly in the last few years, but their potential still remains largely untapped. Here, specifically, the developments in macromolecular self-assemblies and non-covalent drug delivery systems such as polyplexes and drug nanoformulations based on poly(2-oxazoline)s and poly(2-oxazine)s are reviewed. This highly dynamic field benefits particularly from the extensive synthetic toolbox poly(2-oxazoline)s and poly(2-oxazine)s offer and also may have the largest potential for a further development. It is expected that the research dynamics will remain high in the next few years, particularly as more about the safety and therapeutic potential of poly(2-oxazoline)s and poly(2-oxazine)s is learned.

Artificial molecular and nanostructures for advanced nanomachinery

Artificial nanomachines can be broadly defined as manmade molecular and nanosystems that are capable of performing useful tasks, very often, by means of doing mechanical work at the nanoscale. Recent advances in nanoscience allow these tiny machines to be designed and made with unprecedented sophistication and complexity, showing promise in novel applications, including molecular assemblers, self-propelling nanocarriers and in vivo molecular computation. This Feature Article overviews and compares major types of nanoscale machines, including molecular machines, self-assembled nanomachines and hybrid inorganic nanomachines, to reveal common structural features and operating principles across different length scales and material systems. We will focus on systems with feature size between 1 and 100 nm, where classical laws of physics meet those of quantum mechanics, giving rise to a spectrum of exotic physiochemical properties. Concepts of nanomachines will be illustrated by selected seminal work along with state-of-the-art progress, including our own contribution, across the fields. The Article will conclude with a brief outlook of this exciting research area.

Adjustable Intermolecular Interactions Allowing 2D Transition Metal Dichalcogenides with Prolonged Scavenging Activity for Reactive Oxygen Species

There is an increasing demand for control over the dimensions and functions of transition metal dichalcogenides (TMDs) in aqueous solution toward biological and medical applications. Herein, an approach for the exfoliation and functionalization of TMDs in water via modulation of the hydrophobic interaction between poly(ε-caprolactone)-b-poly(ethylene glycol) (PCL-b-PEG) and the basal planes of TMDs is reported. Decreasing the hydrophobic PCL length of PCL-b-PEG from 5000 g mol^-1 (PCL₅₀₀₀ ) to 460 g mol^-1 (PCL₄₆₀ ) significantly increases the exfoliation efficiency of TMD nanosheets because the polymer-TMD hydrophobic interaction becomes dominant over the polymer-polymer interaction. The TMD nanosheets exfoliated by PCL₄₆₀ -b-PEG₅₀₀₀ (460-WS₂ , 460-WSe₂ , 460-MoS₂ , and 460-MoSe₂ ) show excellent and prolonged scavenging activity for reactive oxygen species (ROS), but each type of TMD displays a different scavenging tendency against hydroxyl, superoxide, and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radicals. A mechanistic study based on electron paramagnetic resonance spectroscopy and density functional theory simulations suggests that radical-mediated oxidation of TMDs and hydrogen transfer from the oxidized TMDs to radicals are crucial steps for ROS scavenging by TMD nanosheets. As-prepared 460-TMDs are able to effectively scavenge ROS in HaCaT human keratinocytes, and also exhibit excellent biocompatibility.

Secondary structures of synthetic polypeptide polymers

Synthetic peptide-based polymers can fold into different secondary structures in the same way as do proteins. This review article presents how tuning the polypeptide secondary structure could be a key step to modulate various properties in advanced polymeric materials (size, rigidity, self-assembly,etc.).

Design, synthesis, and characterization of an Fe(ii)-polymer of a redox non-innocent, heteroatomic, polydentate Schiff's base ligand: negative differential resistance and memory behaviour

Complete characterization and memristive study of the electrochemically active, novel Fe(ii)-polymer of a fluorescence active conjugated, hexadentate ligand.

Interaction of Engineered Nanoparticles with the Agri-environment

Nanoparticles with their unique surface properties can modulate the physiological, biochemical, and physicochemical pathways, such as photosynthesis, respiration, nitrogen metabolism, and solute transport. In this context, researchers have developed a wide range of engineered nanomaterials (ENMs) for the improvement of growth and productivity by modulating the metabolic pathways in plants. This class of tailor-made materials can potentially lead to the development of a new group of agrochemical nanofertilizers. However, there are reports that engineered nanomaterials could impart phytotoxicity to edible and medicinal plants. On the contrary, there is a series of ENMs that might be detrimental when applied directly and/or indirectly to the plants. These particles can sometimes readily aggregate and dissolute in the immediate vicinity; the free ions released from the nanomatrix can cause serious tissue injury and membrane dysfunction to the plant cell through oxidative stress. On that note, thorough studies on uptake, translocation, internalization, and nutritional quality assessment must be carried out to understand ENM-plant interactions. This review critically discusses the possible beneficial or adverse aftereffect of nanofertilizers in the immediate environment to interrelate the impacts of ENMs on the crop health and food security management.

Supramolecular structures and self-association processes in polymer systems

Self-organization in a polymer system appears when a balance is achieved between long-range repulsive and short-range attractive forces between the chemically different building blocks. Block copolymers forming supramolecular assemblies in aqueous media represent materials which are extremely useful for the construction of drug delivery systems especially for cancer applications. Such formulations suppress unwanted physicochemical properties of the encapsulated drugs, modify biodistribution of the drugs towards targeted delivery into tissue of interest and allow triggered release of the active cargo. In this review, we focus on general principles of polymer selforganization in solution, phase separation in polymer systems (driven by external stimuli, especially by changes in temperature, pH, solvent change and light) and on effects of copolymer architecture on the self-assembly process.

Selective molecular annealing: in situ small angle X-ray scattering study of microwave-assisted annealing of block copolymers

A new experimental set-up facilitating in situ SAXS during microwave annealing of polymers.

Formulation and stabilization of nano-/microdispersion systems using naturally occurring edible polyelectrolytes by electrostatic deposition and complexation

This review paper presents an overview of the formulation and functionalization of nano-/microdispersion systems composed of edible materials. We first summarized general aspects on the stability of colloidal systems and the roles of natural polyelectrolytes such as proteins and ionic polysaccharides for the formation and stabilization of colloidal systems. Then we introduced our research topics on (1) stabilization of emulsions by the electrostatic deposition using natural polyelectrolytes and (2) formulation of stable nanodispersion systems by complexation of natural polyelectrolytes. In both cases, the preparation procedures were relatively simple, without high energy input or harmful chemical addition. The properties of the nano-/microdispersion systems, such as particle size, surface charge and dispersion stability were significantly affected by the concerned materials and preparation conditions, including the type and concentration of used natural polyelectrolytes. These dispersion systems would be useful for developing novel foods having high functionality and good stability.

Large-pore ordered mesoporous materials templated from non-Pluronic amphiphilic block copolymers

The self-assembly of small surfactants and Pluronic® amphiphilic copolymers has enabled the synthesis of a range of ordered mesoporous materials with high surface area, diverse compositions, variable pore structures and tunable pore sizes. It has recently been realized that non-Pluronic block copolymers can be used as robust templates for the synthesis of novel and high-performance mesoporous materials with crystalline frameworks, ultra-large pores, and abundant pore symmetries, which are not accessible using the Pluronic counterparts. In this review, we introduce the principle of self-assembly of block copolymers and their phase separations, and summarize recently developed synthetic methods and strategies for ordered mesoporous silicas, metal oxides, carbons and metals which have shown superior performances for applications in various fields, including solar cells, batteries, fuel cells, and sensors.

Design of submicron and nanoparticle delivery systems using supercritical carbon dioxide-mediated processes: an overview

Supercritical carbon dioxide technology is an environmentally benign technique that allows precise control of particle morphology, while minimizing organic solvent use for a wide variety of biomedical and pharmaceutical applications. Supercritical carbon dioxide processes have benefits over the conventional particle formation methods in terms of improved control, flexibility and operational ease. This article gives an insight into a variety of supercritical fluid techniques relevant to drug formulation, recent advances and novel applications in the field of controlled delivery. These new methods have been designed to alleviate the scaling-up of the traditional methods for nanoparticle formulation either in the form of polymeric scaffolds, impregnation or nanoencapsules using a simple one-step process to produce micron-size particles.

Micellar crystallization with a hysteresis in temperature

We have investigated the phase diagram of the triblock copolymer P123 solved in water by viscosity measurements for different concentrations and temperatures. The structures of the different phases were identified by surface sensitive neutron diffraction. We find a pronounced hysteresis between heating and cooling. During heating, a highly viscous crystalline fcc phase is found before melting occurs at 44 °C with a simultaneous drop in viscosity. Upon cooling, first a hexagonal phase with low viscosity develops followed by a highly viscous fcc phase. Phase diagrams for the heating and cooling cycle for different concentrations are provided. The hysteric behavior is discussed in relation to the shape of the micelles.

Controlled polymer synthesis--from biomimicry towards synthetic biology

The controlled assembly of synthetic polymer structures is now possible with an unprecedented range of functional groups and molecular architectures. In this critical review we consider how the ability to create artificial materials over lengthscales ranging from a few nm to several microns is generating systems that not only begin to mimic those in nature but also may lead to exciting applications in synthetic biology (139 references).