Size Dispersion Research Articles

Catalysis Synergism by Atomically Precise Bimetallic Nanoclusters Doped with Heteroatoms.

ConspectusBimetallic catalysts hold promise in tailoring the catalytic activity and selectivity of transition metals for important chemical processes due to the synergistic coupling between the constituent elements that can connect catalytical active sites. However, it remains a challenge to construct an ideal bimetallic catalyst to study the respective or cooperative effects of the two transition metals within the bimetallic catalyst on the overall catalytic performance because multiple factors are always convoluted, such as the size dispersity of particles, the inhomogeneous structure, and the unknown exact location of the two metal elements in any particle. Therefore, almost all of the current studies give rise to the statistics of the overall catalytic performance from all of the particles in a bimetallic catalyst or at least the observed performance reflects an ensemble average of all metal atoms in a particle. Atomically precise metal nanoclusters have attracted catalysis scientists since their total structures (core plus surface) were solved by single-crystal X-ray crystallography, thereby providing unparalleled opportunities to build a precise correlation of catalyst structures with catalytic properties at an atomic level. Within this field, we are interested in identifying catalytically active sites and further constructing the active sites by an atom-by-atom manipulation, which are typically challenging for conventional particle-based heterogeneous catalysts and organometallics-based complex catalysts.In this Account, we mainly focus on the extensive efforts to fundamentally understand catalysis synergy in bimetallic nanocluster catalysts doped with heterometallic atoms. We first briefly describe the design rules and chemical synthesis of atomically precise bimetallic nanoclusters doped with heteroatoms including co-reduction, atom substitution, and reconstruction as typical synthesis strategies. We then put particular emphasis on the recent research toward the synergistic effects of surface/subsurface heteroatoms of the bimetallic nanoclusters on controlling the catalytic pathways, in which a series of examples showed that catalytically active sites can be dramatically tailored by the metal heteroatoms (Ru, Cu, Ni, Cd, etc.) located on the surface or subsurface of gold nanoclusters. Other cases indicated that the catalytic activity can be driven by surface heteroatom-ligand motifs of bimetallic nanoclusters. We also discuss the remote effects of nonsurface or kernel heteroatoms located in the cores of bimetallic nanoclusters on improving the catalytic reactions directly occurring on the catalyst surface. Finally, we anticipate that the advances in this research field would not only provide in-depth insight into the intraparticle synergism in bimetallic catalysts for understanding and controlling their catalytic reactivity but also provide valuable guidelines for high-performance catalysts that can be applied in industry.

Effects of Different Co-Feeding Protocols on the Early Weaning of Flathead Grey Mullet (Mugil cephalus) Larvae.

The sustainable expansion of aquaculture relies on a sufficient supply of eggs and larvae, which are the first step of life cycle management. However, marine fish larval rearing generally depends on live feed production, which needs additional facilities and labor. The flathead grey mullet (Mugil cephalus), a promising species for aquaculture diversification, has a precocious digestive system development, supporting the feasibility of early weaning strategies. For these reasons, this study evaluated survival, growth, proximate and fatty acid composition, and gene expression of Mugil cephalus larvae reared under three different weaning protocols. Three co-feeding treatments, two with different Artemia sp. concentrations (A100 and A50, 2 and 1 Artemia sp. mL-1 day-1, respectively) and one with only rotifers administered as live feed along the feeding trial (A0), were assessed from 22 to 36 days post-hatching (dph). The A0 treatment performed better in survival (64.79 ± 7.40%) than the A100 protocol (32.46 ± 12.82%). In contrast, the larvae of the A100 treatment presented significantly higher final length (15.51 ± 0.86 mm) than those of the A0 treatment (12.19 ± 1.45 mm) and higher final weight (41.28 ± 1.48 mg) than those of the A50 and A0 treatments (31.23 ± 3.65 mg and 24.03 ± 7.99 mg, respectively). On the other hand, the expression of digestive enzyme- and somatotropic factor-related genes did not show differences between treatments. The present results support the convenience of treatment A0 in maximizing survival, as rotifers should be maintained until 30-32 dph (until a total larval length of at least 10 mm). However, to improve growth and minimize size dispersion, Artemia sp. addition is recommended from day 26 to day 29 post-hatching (total larval length of 8 to 9 mm).

Synthesis of Glycopolymer Micelles for Antibiotic Delivery.

In this work, we designed biodegradable glycopolymers consisting of a carbohydrate conjugated to a biodegradable polymer, poly(lactic acid) (PLA), through a poly(ethylene glycol) (PEG) linker. The glycopolymers were synthesized by coupling alkyne end-functionalized PEG-PLA with azide-derivatized mannose, trehalose, or maltoheptaose via the click reaction. The coupling yield was in the range of 40-50% and was independent of the size of the carbohydrate. The resulting glycopolymers were able to form micelles with the hydrophobic PLA in the core and the carbohydrates on the surface, as confirmed by binding with the lectin Concanavalin A. The glycomicelles were ~30 nm in diameter with low size dispersity. The glycomicelles were able to encapsulate both non-polar (rifampicin) and polar (ciprofloxacin) antibiotics. Rifampicin-encapsulated micelles were much smaller (27-32 nm) compared to the ciprofloxacin-encapsulated micelles (~417 nm). Moreover, more rifampicin was loaded into the glycomicelles (66-80 μg/mg, 7-8%) than ciprofloxacin (1.2-2.5 μg/mg, 0.1-0.2%). Despite the low loading, the antibiotic-encapsulated glycomicelles were at least as active or 2-4 times more active than the free antibiotics. For glycopolymers without the PEG linker, the antibiotics encapsulated in micelles were 2-6 times worse than the free antibiotics.

Mitochondria-targeted Janus mesoporous nanoplatform for tumor photodynamic therapy

Photodynamic therapy (PDT) is an effective treatment method for tumors. But the specifically accumulated of photosensitizer was very difficult in the tumor site, which greatly limited the efficacy of PDT. Here, mitochondria-targeted Janus mesoporous nanoplatform (JPMO-Pt-CTPP-ZnPc) for PDT was prepared, the nanoplatform has uniform size (275 nm) and good dispersion and biocompatibility. The confocal laser scanning microscopy (CLSM) revealed the signal of ZnPc of JPMO-Pt-CTPP-ZnPc were higher than JPMO-Pt-ZnPc in tumor cells, and flow cytometry results showed the cell uptake efficiency of JPMO-Pt-CTPP-ZnPc was 2.5-fold higher than that of JPMO-Pt-ZnPc. This revealed the modification of CTPP significantly improves the targeting ability of the nanoplatform. In vitro anti-tumor experiment showed the JPMO-Pt-CTPP-ZnPc significantly inhibited the growth of tumor cells upon the irradiation of low-power laser, and the survival rate of cells incubated with 60 µg/mL JPMO-Pt-CTPP-ZnPc was only 3%. Simultaneously, compared with JPMO-Pt-ZnPc (not modified with mitochondria targeting molecules CTPP), the PDT efficacy of JPMO-Pt-CTPP-ZnPc was significantly better, as it has targeted mitochondria in cells.

Evaluation of GHK peptide–heparin interactions in multifunctional liposomal covering

Small biospecific peptides with defined chemical structure and cellular responses are promising alternatives to full-length therapeutic proteins. Identification of these peptides solely or in combination with other bioactive factors and determination of their targets are of substantial interest in current drug delivery research. This study is aimed at the development of new liposomal formulations of ECM-derived GHK peptide known for its multiple regeneration-related activities but poorly recognized cellular targets. In situ association of membranotropic GHK derivative with unilamellar liposomes was performed to prepare GHK-modified liposomes with defined properties. According to DLS, the GHK component on the liposomal surface interacted with heparin in a specific manner compared to other polysaccharides and RGD counterpart, whereas ITC analysis of such interactions was complicated. The results provide a useful tool for screening of bio-interactions of synthetic peptide-presenting liposomes by the DLS technique. They were also employed to produce a multi-functional nanosized GHK-heparin covering for liposomes. The resulting composite liposomes possessed low size dispersity, increased anionic charge, and mechanical rigidity. The heparin component significantly promoted the accumulation of GHK-modified liposomes in 3T3 fibroblasts so that the composite liposomes exhibited the highest cell-penetrating activity. Furthermore, the latter formulation stimulated cell proliferation and strongly inhibited ROS production and GSH depletion under oxidative stress conditions. Together, the results support that cell-surface glycosaminoglycans can be involved in GHK-mediated liposomal delivery, which can be further greatly enhanced by association with heparin. The composite liposomes with GHK-heparin covering can be considered as an advanced GHK-based formulation for therapeutic and cosmeceutical applications.

Interrupting the blood-testis barrier with a flutamide-loaded nanostructured lipid carrier: A novel nonsurgical contraceptive approach for male animals

Flutamide is an antagonist of testosterone, an essential hormone in male reproduction. However, the use of flutamide as a contraceptive agent for nonsurgical castration in veterinary practice remains challenging due to its poor bioavailability. Here, the flutamide-loaded nanostructure lipid carrier (FLT-NLC) was synthesized, and its biological effects were demonstrated by an in vitro blood-testis barrier model. The flutamide was incorporated into the nanostructure lipid carrier by a homogenization method resulting in a high encapsulation efficiency (99.7 ± 0.04%). The FLT-NLC was negatively charged (−27.90 ± 0.10 mV), with a nano size (182.13 ± 0.47 nm) and narrow dispersity index (0.17 ± 0.01). An in vitro release study demonstrated a slower release profile of FLT-NLC when compared with flutamide solution (FLT). The FLT-NLC at doses up to 50 μM showed no significant cytotoxic effects against mouse Sertoli cells (TM4) or mouse fibroblast cells (NIH/3T3) (p > 0.05). An in vitro blood-testis barrier with FLT-NLC demonstrated remarkable lower transepithelial electrical resistance when compared with those lacking FLT-NLC (p < 0.01). Moreover, FLT-NLC significantly decreased the mRNA expression of blood-testis barrier proteins, CLDN11 and OCLN. In conclusion, we successfully synthesized FLT-NLC and confirmed its potential antifertility effects on in vitro blood-testis barrier, thus indicating its possible application as nonsurgical contraception for male animals.

UV-Accelerated Synthesis of Gold Nanoparticle-Pluronic Nanocomposites for X-ray Computed Tomography Contrast Enhancement.

Eco-friendly chemical methods using FDA-approved Pluronic F127 (PLU) block copolymer have garnered much attention for simultaneously forming and stabilizing Au nanoparticles (AuNPs). Given the remarkable properties of AuNPs for usage in various fields, especially in biomedicine, we performed a systematic study to synthesize AuNP-PLU nanocomposites under optimized conditions using UV irradiation for accelerating the reaction. The use of UV irradiation at 254 nm resulted in several advantages over the control method conducted under ambient light (control). The AuNP-PLU-UV nanocomposite was produced six times faster, lasting 10 min, and exhibited lower size dispersion than the control. A set of experimental techniques was applied to determine the structure and morphology of the produced nanocomposites as affected by the UV irradiation. The MTT assay was conducted to estimate IC50 values of AuNP-PLU-UV in NIH 3T3 mouse embryonic fibroblasts, and the results suggest that the sample is more compatible with cells than control samples. Afterward, in vivo maternal and fetal toxicity assays were performed in rats to evaluate the effect of AuNP-PLU-UV formulation during pregnancy. Under the tested conditions, the treatment was found to be safe for the mother and fetus. As a proof of concept or application, the synthesized Au:PLU were tested as contrast agents with an X-ray computed tomography scan (X-ray CT).

Soft interphase volume fraction of composites containing arbitrarily shaped mono−/poly-disperse fillers: Theoretical and numerical investigations

Interphase, a crucial structural component in composite materials connecting the fillers and matrix, typically possesses unique physical properties and plays a crucial role in determining the overall transport and mechanical behaviors of the material system. In this work, we propose a generic theoretical framework to precisely determine the volume fraction fsi of soft interphase around arbitrarily shaped hard fillers, including both convex and concave shapes with arbitrary size dispersity, in three−/two-dimensional (3D/2D) heterogeneous material systems. Specifically, a composite material is regarded as a three-phase structure composed of a homogeneous matrix, hard anisotropic fillers, and their surrounding interpenetrable interphase layers with a constant “thickness” for each filler volume fraction. The seminal hard -core soft-shell (i.e., cherry-pit) model and statistical geometry theories are employed to derive explicit analytical formalism of fsi which is subsequently verified via a series of numerical experiments using Monte Carlo sampling. We systematically investigate the dependence of fsi on the filler characteristics, including filler volume fraction, geometric size factor, fineness, and filler shape and size distributions. Interestingly, we find that filler sphericity can be used as the sole shape descriptor to control the interphase volume fraction for all filler shapes, including those with irregular non-convex morphologies. Our framework provides an efficient and accurate tool for composite design that complements expansive numerical simulations, which is also readily applicable to understanding the effect of fsi on physical properties of composites.

Pre-Liberalization Foundations and the FDI-Based Internationalization of SMEs from Emerging Markets

Research on the internationalization of small and medium enterprises based in emerging markets (EM-SMEs) is gaining momentum, yet, less is known about the specific factors that deter EM-SMEs’ from internationalizing via foreign direct investment (FDI). In this paper, using institutional and organizational imprinting perspectives, we argue that EM-SMEs founded in the era prior to market liberalization are less likely to internationalize via FDI than those founded during or after market liberalization. We also argue that this effect is moderated by EM-SMEs’ size and ownership dispersion. Our data used to test our hypotheses is based on 2277 SMEs from 14 emerging markets. Overall, we contribute to an improved understanding of the factors that determine the FDI-based internationalization of SMEs from emerging markets.

Chitosan‐coated nanoliposomes for the enhanced stability of walnut angiotensin‐converting enzyme (ACE) inhibitory peptide

This study encapsulated walnut angiotensin-converting enzyme (ACE) inhibitory peptides within nanoliposomes and then modified them with chitosan. The resulting effect of the nanoliposome loading and chitosan coating on physicochemical characteristics, stability, bioactivity, chemical structure, and morphology of the encapsulated peptides was assessed. The resulting particle size and polymer dispersity index revealed that the chitosan-coated nanoliposomes loaded with walnut ACE inhibitory peptides (WAIP) (CL-P) exhibited higher physical stability compared with the nanoliposomes loaded with WAIP (L-P). The encapsulation efficiency (EE) of CL-P increased from 73.32% to 76.13% after chitosan modification, and the EE of L-P and CL-P could be maintained by storage at 4°C. In addition, the antioxidant activity and ACE inhibitory activity of the peptides were effectively protected by L-P and CL-P during storage. Fourier transform infrared spectroscopy showed that the nanoliposomes were bound in ionic form with both the peptides and chitosan. Transmission electron micrographs indicated the presence of vesicle-like carriers with a reservoir-type structure. This study highlights the potential of nanoliposomes and their modification with chitosan to increase the stability and bioactivity retention of ACE inhibitory peptides. PRACTICAL APPLICATION: Chitosan-coated nanoliposomes loaded with walnut ACE inhibitory peptides were prepared in this study. Chitosan coating increased nanoliposomes' encapsulation efficiency and provided higher physical stability. In addition, the bioactivity of the walnut ACE peptides was effectively protected during storage. This study was relevant for improving the storage and transportation used for nanoliposome systems applied in the food and health product industry.

Hybrid Ligand Polymerization for Weakly Confined Lead Halide Perovskite Quantum Dots

Rational ligand passivation is essential to achieve a higher performance of weakly confined lead halide perovskite quantum dots (PQDs) via a mechanism of surface chemistry and/or microstrain. In situ passivation with 3-mercaptopropyltrimethoxysilane (MPTMS) produces CsPbBr3 PQDs with an enhanced photoluminescence quantum yield (PLQY, ΦPL) of up to 99%; meanwhile, charge transport of the PQD film can be enhanced by one order of magnitude. Herein, we examine the effect of the molecular structure of MPTMS as the ligand exchange agent in comparison to octanethiol. Both thiol ligands promote crystal growth of PQDs, inhibit nonradiative recombination, and cause blue-shifted PL, while the silane moiety of MPTMS manipulates surface chemistry and outperforms owing to its unique cross-linking chemistry characterized by FTIR vibrations at 908 and 1641 cm-1. Emergence of the diagnostic vibrations is ascribed to hybrid ligand polymerization arising from the silyl tail group that confers the advantages of narrower size dispersion, lower shell thickness, more static surface binding, and higher moisture resistance. In contrast, the superior electrical property of the thiol-passivated PQDs is mostly determined by the covalent S-Pb bonding on the interface.

Understanding the evolution of particle size dispersion with time in a fluidised bed granulation process

Minimisation of final size dispersion remains an important objective of fluidised bed granulation. Some of the factors that control the evolution of the granule size distribution with time in such a process are examined using a validated aggregation model. The aim is to understand the intrinsic behaviour of size dispersion versus time with an approach that is not specific to a particular system of fluidised granulation. Because relative size dispersion (size dispersion compared to the mean size) is also important, the study also examines the evolution of mean granule size versus time. The model includes an aggregation rate that is time and size dependent and a granule kinetic energy dissipation mechanism. The relative importance of these components of the model is quantified in terms of how they control the output and it is shown that the action of the energy absorption mechanism (implemented using the viscous Stokes criterion) makes the dominant contribution although the interplay with the other effects is also significant. Mean granule volume monotonically approaches a quasi-stable asymptotic value while standard deviation in granule volume passes through a peak value before falling to a lower, quasi-stable asymptotic value. The reasons underlying such behaviour are outlined. Two new temporal parameters, an equivalent aggregation time constant and a Stokes time constant, are developed and can be employed to predict and interpret system behaviour. Such knowledge can then be applied to suggest how dispersion in size can be controlled within certain intrinsic limits, which will be of interest to the industry.

Modeling the Breakdown of Dielectrics Loaded With Conducting Particles

This study addresses the electrical breakdown of dielectrics loaded with randomly dispersed conducting particles. A simple stochastic breakdown model is proposed and used to provide information on the tree structure and dielectric breakdown strength. Parametric simulations suggest an important role of the particle fraction and microstructure (regular versus aggregated) on the breakdown strength while the particle size and size dispersity have limited effects. The obtained results have been recast in terms of geometrical parameters describing the particle structure and the minimum-gap path (path having the shortest length of dielectrics) is found to correlate quite well with numerical results. This suggests that simple geometrical quantities are relevant to provide quantitative predictions of breakdown strength for such materials.

The Problems of TiO2 Nanoparticle Additives in Food Additives

With the improvement of people's living standards and the development of the food industry, TiO2, as a food additive, has been increasingly applied in the food processing industry, such as a preservative, colorant, antioxidant, thickening agent, etc. It can play an antibacterial role in food processing, but can cause allergic reactions if used for a long time or in large quantities. For example, when TiO2 comes into contact with food, it will make the taste of some food deteriorate and even lead to severe food poisoning. In addition, if TiO2 cannot be completely decomposed during processing, some harmful substances will remain. Research shows that in most areas of our country there are some people with food allergies. It can be seen that TiO2, as a food additive, may have an impact on human body during food processing. Therefore, mixing with other substances should be avoided as far as possible. TiO2 nanoparticles have excellent nanoscale effect and dispersion, as well as high mechanical strength and chemical stability, so they have a broad application prospect in food additives. TiO2 nanoparticles can be used as food additives, mainly by the covalent bonding of iron and non-iron ions in polymer organic materials to form nano-scale TiO2 gel. The gel has a high specific surface area and porosity, and can be added to food as an anti-coagulant. Due to the size effect and dispersion of nanoparticles, nano-TiO2 gel has advantages such as better, faster synthesis speed and lower cost compared with traditional dispersants.

An experimental study of the sooting behavior of a partially premixed flame under moderately rich conditions

Soot and its gaseous precursors are quantified in detail (precursors up to 166 amu, volume fraction, particle size, number concentration, and light emissivity dispersion exponent) in a laminar partially premixed counterflow flame of ethylene. The investigated flame has an equivalence ratio Φ = 2.43 and a mixture fraction Zst = 0.4, resulting in a distinct double-flame structure consisting of a rich premixed flame component and a diffusion flame component, both stabilized on the fuel side of the stagnation plane. The value of the equivalence ratio makes the premixed flame the dominant contributor to soot production, with soot being oxidized completely by OH from the diffusion flame component. Particle size is measured to increase quasi-monotonically, but remains within a few nanometers throughout the soot forming region. Aromatic species are primarily formed in the post flame region of the premixed flame. Their mole fractions peak close to the premixed flame and decrease as the diffusion flame is approached. The experimentally measured gaseous species are captured well by kinetic models, with the exception of two critical species in soot chemistry: benzene and naphthalene.

Structural and Magnetic Characterization of Nd-Pr-Fe-B Sintered Magnet Machining Wastes.

Nd-Pr-Fe-B sintered magnets are considered important for emerging technologies. They are fundamental to the energy matrix transition, such as electric and hybrid vehicles and wind turbines. The production of these magnets generates tons of residues in the machining process step. Since China dominates the rare-earth (RE) market, leading to supply shortages, processing wastes are a promising alternative for recycling or reusing RE materials. Due to the amount generated and the chemical composition, containing up to 30 wt % of critical rare-earth elements, the studies of RE magnets are expanding in the current circular economy scenario. In this work, Nd-Pr-Fe-B machining wastes from two different machining processes (diamond cutting and grinding) were characterized by X-ray diffraction, Mössbauer spectroscopy, vibrating sample magnetometer with first-order-reversal-curves, scanning electron microscopy, X-ray fluorescence, elemental analysis, and X-ray photoelectron spectroscopy. The results showed that the degradation of the phases in both wastes is relatively strong. The phases of the magnets are decomposed into oxides, hydroxides, and hydrated oxides such as Nd(OH)3, ferrihydrite, and metallic iron. In addition, the machining process provokes a change in the iron vicinity of the Nd2Fe14B phase. The presence of impurities and the wide dispersion of particle sizes resulted in low magnetic properties and affected the magnetization behavior of the machining waste. Using different characterization techniques, it was found that the oxides formed during the machining processes are located on the surfaces of the particles, while the center consists of a nondegraded Nd2Fe14B phase. It was also found that the Nd-Pr-Fe-B wastes have similarities, indicating that it is possible to mix wastes from different machining processes before recycling. The complete characterization of the Nd-Pr-Fe-B machining residues indicated that different reuse and recycling strategies can be evaluated to improve the efficiency of reusing these machining wastes as secondary sources.

Design, Synthesis, Characterization, and Evaluation of the Anti-HT-29 Colorectal Cell Line Activity of Novel 8-Oxyquinolinate-Platinum(II)-Loaded Nanostructured Lipid Carriers Targeted with Riboflavin.

Colorectal cancer is occasionally called colon or rectal cancer, depending on where cancer begins to form, and is the second leading cause of cancer death among both men and women. The platinum-based [PtCl(8-O-quinolinate)(dmso)] (8-QO-Pt) compound has demonstrated encouraging anticancer activity. Three different systems of 8-QO-Pt-encapsulated nanostructured lipid carriers (NLCs) with riboflavin (RFV) were investigated. NLCs of myristyl myristate were synthesized by ultrasonication in the presence of RFV. RFV-decorated nanoparticles displayed a spherical shape and a narrow size dispersion in the range of 144-175 nm mean particle diameter. The 8-QO-Pt-loaded formulations of NLC/RFV with more than 70% encapsulation efficiency showed sustained in vitro release for 24 h. Cytotoxicity, cell uptake, and apoptosis were evaluated in the HT-29 human colorectal adenocarcinoma cell line. The results revealed that 8-QO-Pt-loaded formulations of NLC/RFV showed higher cytotoxicity than the free 8-QO-Pt compound at 5.0 µM. All three systems exhibited different levels of cellular internalization. Moreover, the hemotoxicity assay showed the safety profile of the formulations (less than 3.7%). Taken together, RFV-targeted NLC systems for drug delivery have been investigated for the first time in our study and the results are promising for the future of chemotherapy in colon cancer treatment.

ATRP Enhances Structural Correlations In Polymerization-Induced Phase Separation.

Synthetic methods to control the structure of materials at sub-micron scales are typically based on the self-assembly of structural building blocks with precise size and morphology. On the other hand, many living systems can generate structure across a broad range of length scales in one step directly from macromolecules, using phase separation. Here, we introduce and control structure at the nano- and microscales through polymerization in the solid state, which has the unusual capability of both triggering and arresting phase separation. In particular, we show that atom transfer radical polymerization (ATRP) enables control of nucleation, growth, and stabilization of phase-separated poly-methylmethacrylate (PMMA) domains in a solid polystyrene (PS) matrix. ATRP yields durable nanostructures with low size dispersity and high degrees of structural correlations. Furthermore, we demonstrate that the length scale of these materials is controlled by the synthesis parameters.

ATRP Enhances Structural Correlations In Polymerization‐Induced Phase Separation**

AbstractSynthetic methods to control the structure of materials at sub‐micron scales are typically based on the self‐assembly of structural building blocks with precise size and morphology. On the other hand, many living systems can generate structure across a broad range of length scales in one step directly from macromolecules, using phase separation. Here, we introduce and control structure at the nano‐ and microscales through polymerization in the solid state, which has the unusual capability of both triggering and arresting phase separation. In particular, we show that atom transfer radical polymerization (ATRP) enables control of nucleation, growth, and stabilization of phase‐separated poly‐methylmethacrylate (PMMA) domains in a solid polystyrene (PS) matrix. ATRP yields durable nanostructures with low size dispersity and high degrees of structural correlations. Furthermore, we demonstrate that the length scale of these materials is controlled by the synthesis parameters.

In Situ Nanoarchitectonics of a MOF Hydrogel: A Self-Adhesive and pH-Responsive Smart Platform for Phototherapeutic Delivery.

Metal-organic frameworks (MOFs) have dramatically changed the fundamentals of drug delivery, catalysis, and gas storage as a result of their porous geometry, controlled architecture, and ease of postsynthetic modification. However, the biomedical applications of MOFs still remain a less explored area due to the constraints associated with handling, utilizing, and site-specific delivery. The major drawbacks associated with the synthesis of nano-MOFs are related to the lack of control over particle size and inhomogeneous dispersion during doping. Therefore, a smart strategy for the in situ growth of a nano-metal-organic framework (nMOF) has been devised to incorporate it into a biocompatible polyacrylamide/starch hydrogel (PSH) composite for therapeutic applications. In this study, the post-treatment of zinc metal ion cross-linked PSH with the ligand solution generated the nZIF-8@PAM/starch composites (nZIF-8, nano-zeolitic imidazolate framework-8). The ZIF-8 nanocrystals thus formed have been found to be evenly dispersed throughout the composites. This newly designed nanoarchitectonics of an MOF hydrogel was found to be self-adhesive, which also exhibited improved mechanical strength, a viscoelastic nature, and a pH-responsive behavior. Taking advantage of these properties, it has been utilized as a sustained-release drug delivery platform for a potential photosensitizer drug (Rose Bengal). The drug was initially diffused into the in situ hydrogel, and then the entire scaffold was analyzed for its potential in photodynamic therapy against bacterial strains such as E. coli and B. megaterium. The Rose Bengal loaded nano-MOF hydrogel composite exhibited remarkable IC50 values within the range of 7.37 ± 0.04 and 0.51 ± 0.05 μg/mL for E. coli and B. megaterium. Further, reactive oxygen species (ROS) directed antimicrobial potential was validated using a fluorescence-based assay. This smart in situ nanoarchitectonics hydrogel platform can also serve as a potential biomaterial for topical treatment including wound healing, lesions, and melanoma.