Pd Nanoparticle-Loaded Smart Microgel-Based Membranes as Reusable Catalysts

Nanosized core-shell bio-hybrid microgels and their internal structure

Microgels are versatile materials with applications across biomedicine, materials science, and beyond. Their controllable size and composition enables tailoring specific properties, yet characterizing their internal structures on the nanoscale remains challenging. Super-resolution fluorescence microscopy (SRFM) effectively analyzes sub-μm structures, including microgels, offering a tool for investigating more complex systems such as core-shell microgels. Understanding their internal structure, in particular interpenetration at the soft-soft interface between core and shell and accessibility for guest molecules, is vital for rationally designing predictable functionalities. This study examines the core-shell morphology and the accessibility for guest molecules of bio-hybrid DNA-poly(N-isopropylmethacrylamide) microgels at three stages of shell polymerization using SRFM. Covalent fluorescence labeling probes the core polymer, co-polymerized with N,N'-bis(acryloyl)cystamine, which provides visual insight into core and shell compartmentalization. The results demonstrate core polymer interpenetration into the shell without compromising its original structure, and additionally allow us to determine the size- and hydrophobicity dependent accessibility of the microgel core. This, offering new perspectives on the internal architecture of core-shell microgels, contributes to the in-depth understanding of their complex behavior, potentially guiding the rational design of new microgel drug delivery systems, taking into account the complex interplay of polarity, size and charge of guest molecules.

Pre-trained artificial intelligence-aided analysis of nanoparticles using the segment anything model

Complex structures can be understood as compositions of smaller, more basic elements. The characterization of these structures requires an analysis of their constituents and their spatial configuration. Examples can be found in systems as diverse as galaxies, alloys, living tissues, cells, and even nanoparticles. In the latter field, the most challenging examples are those of subdivided particles and particle-based materials, due to the close proximity of their constituents. The characterization of such nanostructured materials is typically conducted through the utilization of micrographs. Despite the importance of micrograph analysis, the extraction of quantitative data is often constrained. The presented effort demonstrates the morphological characterization of subdivided particles utilizing a pre-trained artificial intelligence model. The results are validated using three types of nanoparticles: nanospheres, dumbbells, and trimers. The automated segmentation of whole particles, as well as their individual subdivisions, is investigated using the Segment Anything Model, which is based on a pre-trained neural network. The subdivisions of the particles are organized into sets, which presents a novel approach in this field. These sets collate data derived from a large ensemble of specific particle domains indicating to which particle each subdomain belongs. The arrangement of subdivisions into sets to characterize complex nanoparticles expands the information gathered from microscopy analysis. The presented method, which employs a pre-trained deep learning model, outperforms traditional techniques by circumventing systemic errors and human bias. It can effectively automate the analysis of particles, thereby providing more accurate and efficient results.

Laser Patterning of Porous Support Membranes to Enhance the Effective Surface Area of Thin-Film Composite-Facilitated Transport Membranes for CO2 Separation

Although thin-film composite membranes have achieved great success in CO2 separation, further improvements in the CO2 permeance are required to reduce the size and cost of the CO2 separation process. Herein, we report the fabrication of composite membranes with high CO2 permeability using a laser-patterned porous membrane as the support membrane. High-aspect-ratio micropatterns with well-defined micropores on their surface were carved on microporous polymer supports by a direct laser writing process using a short-pulsed laser. By using a Galvano scanner and optimizing the laser conditions and target materials, in-plane micropatterns, such as microhole arrays, microline grating, microlattices, and out-of-plane hierarchical micropatterns, were created on porous membranes. An aqueous suspension of hydrogel microparticles doped with an amine-based mobile carrier was sprayed onto the patterned surface to form a defect-free thin separation layer. The surface area of the separation layer on the patterned support is up to 80% larger than that of flat pristine membranes, resulting in a 52% higher CO2 permeance (1106 GPU) with a CO2/N2 selectivity of 172. The laser-patterned porous membranes allow the development of inexpensive and high-performance functional membranes not only for CO2 separation but also for other applications, such as water treatment, cell culture, micro-TAS, and membrane reactors.

A Comprehensive Review of Radiation-Induced Hydrogels: Synthesis, Properties, and Multidimensional Applications

At the forefront of advanced material technology, radiation-induced hydrogels present a promising avenue for innovation across various sectors, utilizing gamma radiation, electron beam radiation, and UV radiation. Through the unique synthesis process involving radiation exposure, these hydrogels exhibit exceptional properties that make them highly versatile and valuable for a multitude of applications. This paper focuses on the intricacies of the synthesis methods employed in creating these radiation-induced hydrogels, shedding light on their structural characteristics and functional benefits. In particular, the paper analyzes the diverse utility of these hydrogels in biomedicine and agriculture, showcasing their potential for applications such as targeted drug delivery, injury recovery, and even environmental engineering solutions. By analyzing current research trends and highlighting potential future directions, this review aims to underscore the transformative impact that radiation-induced hydrogels could have on various industries and the advancement of biomedical and agricultural practices.

Silica@poly(chitosan-N-isopropylacrylamide-methacrylic acid) microgels: Extraction of palladium (II) ions and in situ formation of palladium nanoparticles for pollutant reduction

Most of the transition metal ions and organic dyes are toxic in nature. Therefore, their removal from water is imperative for human health. For this purpose, various types of systems have been developed to tackle either transition metal ions or organic dyes individually. A core-shell microgel system is introduced which is capable of effectively removing both types (toxic organic dyes and transition metal ions) of pollutants. A long-rod-shaped silica@poly(chitosan-N-isopropylacrylamide-methacrylic acid) S@P(CS-NIPAM-MAA) S@P(CNM) core-shell microgel system was developed by free radical precipitation polymerization method (FRPPM). S@P(CNM) was utilized as an adsorbent for extracting palladium (II) (Pd (II)) ions from water under different concentrations of S@P(CNM), several agitation times, palladium (II) ion content, and pH levels. The adsorption data of Pd (II) ions on S@P(CNM) was evaluated by various adsorption isotherms. The kinetic study was investigated by employing pseudo-2nd order (Ps2O), Elovich model (ElM), intra-particle diffusion (IPDM), and pseudo-1st order (Ps1O). Additionally, palladium nanoparticles (Pd NPs) were generated via in-situ reduction of adsorbed Pd (II) ions within the P(CNM) shell region of S@P(CNM). The resulting Pd NPs loaded S@P(CNM) exhibited the capability to reduce organic pollutants like methyl orange (MeO), 4-nitrophenol (4NiP), methylene blue (MeB), and Rhodamine B (RhB) from aqueous medium. 0.766 min-1, 0.433 min-1, 0.682 min-1, and 1.140 min-1 were the values of pseudo 1st order rate constant (kobs) for catalytic reduction of MeB, 4NiP, MeO, and RhB respectively. The S@Pd-P(CNM) system exhibits significant catalytic potential for various organic transformations.

A review of stimuli-responsive polymer-based gating membranes

The formation and properties of smart (stimuli-responsive) membranes are reviewed, with a special focus on temperature and pH triggering of gating to water, ions, polymers, nanoparticles, or other molecules of interest. The review is organized in two parts, starting with all-smart membranes based on intrinsically smart materials, in particular of the poly(N-isopropylacrylamide) family and similar polymers. The key steps of membrane fabrication are discussed, namely the deposition into thin films, functionalization of pores, and the secondary crosslinking of pre-existing microgel particles into membranes. The latter may be free-standing and do not necessitate the presence of a porous support layer. The temperature-dependent swelling properties of polymers provide a means of controlling the size of pores, and thus size-sensitive gating. Throughout the review, we highlight "positive" (gates open) or "negative" (closed) gating effects with respect to increasing temperature. In the second part, the functionalization of porous organic or inorganic membranes of various origins by either microgel particles or linear polymer brushes is discussed. In this case, the key steps are the adsorption or grafting mechanisms. Finally, whenever provided by the authors, the suitability of smart gating membranes for specific applications is highlighted.

The compression of deformed microgels at an air/water interface

The compression of deformed hydrogel microspheres (microgels) at air/water interfaces was investigated using a Langmuir-Blodgett trough with simultaneous in situ visualization of the process using a fluorescent microscope. The relationship between the structure of the microgel arrays and the compression behavior was clarified using microgels with different degrees of crosslinking.

Compression and Ordering of Hollow Microgels in Monolayers Formed at Liquid-Liquid Interfaces

Monolayers of polymer microgels with a spherical cavity adsorbed at the liquid-liquid interface were studied using mesoscopic computer simulations. One liquid, named water, was always considered as a good solvent, while the microgel solubility in the second liquid, named oil, was varied. The symmetric and asymmetric cases of vanishing and the strong differences in solubility between the network particles and the liquids were considered. The simulations provided us with an insight into the shape and volume changes of the microgels upon compression, making it possible to relate the response of the individual network with the collective order and structure of the monolayer. Similar to regular microgels, the compression of the monolayer of hollow particles led to a decrease in lateral sizes accompanied by shape transformation from a flattened to a nearly spherical shape. However, the presence of a cavity filled with solvent caused some unique differences in the behavior of the system. The adsorption pathway of hollow microgels at the liquid interface predefines: (a) the position of the particles with respect to the interface and (b) the structure of the monolayer. A striking discovery is that in the symmetric case of similar solubility of the microgel in both liquids, it is possible to produce a monolayer in which one part of the network faces the aqueous phase and the other part faces the oil phase. The polymer concentration profiles plotted along the normal to the interface reveal a redistribution of polymeric mass of the microgels relative to the interface, distinguishing between the microgels whose cavities are filled with water and oil, respectively. Moreover, the ratio between the microgels faced in water and oil does not change upon compression and predetermines the response and order of the monolayer.

A Critical Review of Palladium Nanoparticles Decorated in Smart Microgels

Palladium nanoparticles (Pd) combined with smart polymer microgels have attracted significant interest in the past decade. These hybrid materials have unique properties that make them appealing for various applications in biology, environmental remediation, and catalysis. The responsive nature of the microgels in these hybrids holds great promise for a wide range of applications. The literature contains diverse morphologies and architectures of Pd nanoparticle-based hybrid microgels, and the architecture of these hybrids plays a vital role in determining their potential uses. Therefore, specific Pd nanoparticle-based hybrid microgels are designed for specific applications. This report provides an overview of recent advancements in the classification, synthesis, properties, characterization, and uses of Pd nanostructures loaded into microgels. Additionally, the report discusses the latest progress in biomedical, catalytic, environmental, and sensing applications of Pd-based hybrid microgels in a tutorial manner.

Swelling and Collapse of Cylindrical Polyelectrolyte Microgels

In this study, we propose computer simulations of charged cylindrical microgels. The effects of cross-linking density, aspect ratio, and fraction of charged groups on the microgel swelling and collapse with a variation in the solvent quality were studied. The results were compared with those obtained for equivalent neutral cylindrical microgels. The study demonstrated that microgels' degree of swelling strongly depends on the fraction of charged groups. Polyelectrolyte microgels under adequate solvent conditions are characterized by a larger length and thickness than their neutral analogues: the higher the fraction of charged groups, the longer their length and greater their thickness. Microgels' collapse upon solvent quality decline is characterized by a decrease in length and non-monotonous behavior of its thickness. First, the thickness decreases due to the attraction of monomer units (beads) upon collapse. The further thickness increase is related to the surface tension, which tends to reduce the anisotropy of collapsed objects (the minimum surface energy is known to be achieved for the spherical objects). This reduction is opposed by the network elasticity. The microgels with a low cross-linking density and/or a low enough aspect ratio reveal a cylinder-to-sphere collapse. Otherwise, the cylindrical shape is preserved in the course of the collapse. Aspect ratio as a function of the solvent quality (interaction parameter) demonstrates the maximum, which is solely due to the electrostatics. Finally, we plotted radial concentration profiles for network segments, their charged groups, and counterions.