Aggregation Kinetics Research Articles

Refining α-synuclein seed amplification assays to distinguish Parkinson’s disease from multiple system atrophy

BackgroundParkinson’s disease (PD) and multiple system atrophy (MSA) are two distinct α-synucleinopathies traditionally differentiated through clinical symptoms. Early diagnosis of MSA is problematic, and seed amplification assays (SAAs), such as real-time quaking-induced conversion (RT-QuIC), offer the potential to distinguish these diseases through their underlying α-synuclein (α-Syn) pathology and proteoforms. Currently, SAAs provide a binary result, signifying either the presence or absence of α-Syn seeds. To enhance the diagnostic potential and biological relevance of these assays, there is a pressing need to incorporate quantification and stratification of α-Syn proteoform-specific aggregation kinetics into current SAA pipelines.MethodsOptimal RT-QuIC assay conditions for α-Syn seeds extracted from PD and MSA patient brains were determined, and assay kinetics were assessed for α-Syn seeds from different pathologically relevant brain regions (medulla, substantia nigra, hippocampus, middle temporal gyrus, and cerebellum). The conformational profiles of disease- and region-specific α-Syn proteoforms were determined by subjecting the amplified reaction products to concentration-dependent proteolytic digestion with proteinase K.ResultsUsing our protocol, PD and MSA could be accurately delineated using proteoform-specific aggregation kinetics, including α-Syn aggregation rate, maximum relative fluorescence, the gradient of amplification, and core protofilament size. MSA cases yielded significantly higher values than PD cases across all four kinetic parameters in brain tissues, with the MSA-cerebellar phenotype having higher maximum relative fluorescence than the MSA-Parkinsonian phenotype. Statistical significance was maintained when the data were analysed regionally and when all regions were grouped.ConclusionsOur RT-QuIC protocol and analysis pipeline can distinguish between PD and MSA, and between MSA phenotypes. MSA α-Syn seeds induce faster propagation and exhibit higher aggregation kinetics than PD α-Syn, mirroring the biological differences observed in brain tissue. With further validation of these quantitative parameters, we propose that SAAs could advance from a yes/no diagnostic to a theranostic biomarker that could be utilised in developing therapeutics.

Whole process of fab antibody aggregation in intestinal environment and their aggregation regulation: An insight from static and concentration perturbation aggregations.

This work revealed the aggregation and aggregation inhibition mechanisms of Fab antibody in a simulated intestinal fluid via static and concentration perturbation aggregations to meet the challenges of oral antibody therapy. Results showed that Fab aggregation was highly concentration dependent, mainly determined by the β-sheet's stacking and amyloid fibers' extension at low (1 mg/mL) and the twine of β-strands' turn at high (20 mg/mL) concentrations. During the incubation of 0-240 min, Fab was continuously aggregating, but with some rearrangements on its spatial conformation: α-helix and β-sheet formation with β-turn and random coil unfolding, which expanded the aggregates' hydrophobic core and extended β-sheet structure through the π-π stacking of aromatic amino acids. The aggregation kinetics indicated that high Fab concentrations promoted high aggregates but the growth of amyloid fibers took a long time, while low to high concentration fluctuation promoted the formation of Fab aggregates. Molecular docking and molecular dynamics simulations suggested that Arg, PEG 10000, and Poloxamer 188 reduced the potential energy; PEG 10000 and Tween 20 enhanced steric hindrance by spontaneously binding through competitive hydrogen bonding without disturbing Fab's conformation. This work can provide promising approaches for our daily health management by facilitating the materialization of Fab-based oral antibody therapy.

Shedding Light on Protein Aggregates by Bisindolyl-Based Fluorogenic Probes: Unveiling Mechanistic Pathways and Real-Time Tracking of Protein Aggregation.

Herein, we synthesized a pair of oxidized bisindolyl derivatives with anthracene (probe 1) and pyrene (probe 2) fluorophores for selective protein aggregate detection, crucial in disorders like Alzheimer's disease. Probe 1 exhibited a significant "turn-on" response (∼12-fold) and concomitant red shift (∼21 nm) with lysozyme aggregates, while showing ∼3-fold fluorescence enhancement with insulin aggregates, indicating high selectivity for aggregated proteins. Probe 2 showed similar responses but with less preference, as compared to probe 1. Furthermore, the thiazole orange (TO) assay confirmed the ability of probe 1 to detect protein fibrils and monitor aggregation kinetics (with distinct responses at different phases of aggregation). Molecular docking calculations demonstrated efficient binding of probes to aggregated proteins, stabilized primarily by hydrophobic interactions (π-π stacking). Additionally, density functional theory (DFT)-based global reactivity descriptors were computed to assess the reactivity and preferential docking sites. This work underscores the potential for novel therapeutic strategies targeting protein aggregates and early diagnosis of protein disorders.

Manipulating Aggregation Kinetics toward Efficient All-Printed Organic Solar Cells.

The power conversion efficiencies (PCEs) of all-printed organic solar cells (OSCs) remain inferior to those of spin-coated devices, primarily due to morphological variations within the bulk heterojunction processed via diverse coating/printing techniques. Herein, cyclohexyl is introduced as outer side chains to formulate a non-fullerene acceptor, BTP-Cy, aimed at modulating the molecular aggregation in solution and subsequent film formation kinetics during printing. Investigations demonstrate that BTP-Cy molecule with cyclohexyl side chains exhibits enhanced intermolecular π-π stacking, optimal solution aggregation size, and favorable phase separation. Consequently, PB3:FTCC-Br:BTP-Cy-based OSCs achieve remarkable PCEs of 20.2% and 19.5% via spin-coating and blade-coating, respectively. Furthermore, a 23.6 cm2 module exhibits a remarkable efficiency of 16.7%. This study offers a fresh perspective on tailoring the film formation kinetics of photoactive materials during printing through molecular design, paving a novel path to enhance the efficiency of all-printed OSCs.

Inhibition and Degradation of Amyloid Beta Fibrils by Peptide Inhibitors.

Abnormal amyloid beta (Aβ) aggregation in the form of plaques and its deposition across the human nerve cells are a major hallmark of Alzheimer's disease. Aβ aggregation dynamics and, more importantly, various drugs' effects, either to inhibit the fibril aggregation or to degrade the mature fibrils, have been an area of active research. Large molecule (peptide-based) inhibitors, such as decapeptide (RYYAAFFARR) and pentapeptide (LPFFD), show inhibition/degradation effects on amyloid beta fibrils. Herein, a mathematical model has been proposed. The model simulates Aβ aggregation and inhibitory/degradative action of peptide inhibitors on Aβ fibrillation. Model parameters are tuned by curve fitting the experimental data. The tuned model is used to predict experimental data at different initial dose/fibril concentrations. Model predicted results are observed to be in good agreement with the reported experimental data, demonstrating model's applicability at the molecular level. Sensitivity analyses of the model parameters on the fibril concentration further establish the robustness of the proposed model.

Enhancing cooperative multi-agent reinforcement learning through the integration of R-STDP and federated learning

This paper introduces a novel approach to enhance the stability and efficiency of R-STDP in the context of federated learning. The primary objective is to stabilize the unbounded growth of R-STDP and make it more responsive to real-time changes. The methodology involves integrating R-STDP with Spiking Neural Networks and employing the norm of the neural network model for adjusting weighted aggregation in federated learning systems. The proposed method incorporates a mechanism where weights decay over time, depending on the duration since the agent last published its model. Additionally, the sampling time is dynamically adjusted based on the Euclidean norm, which measures the distance between the weight matrices of the agents and the server. The results demonstrate that the proposed event-triggered federated learning method significantly enhances learning speed and performance. At the same time, the dynamic aggregation interval efficiently reduces communication between the agents and the central server, especially after model convergence. This research presents a significant advancement in federated learning and offers a more stable, responsive, and efficient learning process.

Optimal selection of diagnostic method for diabetes mellitus using complex bipolar fuzzy dynamic data

Diabetes mellitus refers to a collection of metabolic disorders that affect the way carbohydrates are processed in the body. It is a prominent worldwide health issue. Precise and reliable decision-making methods are critical for identifying the most effective method of detecting diabetes mellitus. This research work highlights the resolution of the aforementioned decision-making scenarios by utilizing dynamic aggregation operators in the complex bipolar fuzzy (CBF) framework. Dynamic aggregation operators, known for their versatility and accuracy, play an important role in decision-making processes by successfully incorporating changes in data over time. The complex bipolar fuzzy set (CBFS) theory is advantageous in efficiently capturing vagueness because it can incorporate extensive problem descriptions that exhibit periodicity and bipolar ambiguity. In this study, we introduce two novel dynamic aggregation operators, namely, the CBF dynamic ordered weighted averaging (CBFDyOWA) operator and the CBF dynamic ordered weighted geometric (CBFDyOWG) operator. In addition, we examine some important characteristics of these operators. We formulate a modified score function to address the shortcomings of the current score function in the CBF settings. Furthermore, we employ these operators to offer a systematic technique to tackle multiple attribute decision-making (MADM) problems using CBF data. We resolve a MADM problem by determining the most appropriate method for diagnosing diabetes mellitus using the developed operators, demonstrating their usefulness in decision-making procedures. Finally, we perform an in-depth comparison to show the stability and dependability of the derived techniques by comparing them with a wide range of their existing counterparts.

Colloidal stability of UV-aged and protein-coated nanoplastics in natural waters under warming.

Nanoplastics, particles smaller than 1,000 nm that are produced by degradation of plastic debris, pose an environmental threat and may endanger natural ecosystems and human health. In aquatic environments, the large surface area and high surface energy of NPs facilitate their interactions with the surroundings; thus, understanding their behavior, transport, and fate is essential. In this study, we investigated the individual and combined effects of UV aging and protein coating on the stability of NPs in aquatic environments under elevated temperatures. UV-aged NPs were created via indoor UV lamp exposure, and protein coating was achieved by introducing bovine serum albumin (BSA). Sequential processes produced UV+BSA and BSA+UV-coated NPs for comprehensive analysis. Aggregation kinetics and stability were examined in electrolyte solutions (NaCl and CaCl2) and natural waters. Results indicated that BSA coating improved the colloidal stability of NPs in electrolyte solutions by promoting steric repulsion, a trend observed in rivers, lakes, and seawater but not in groundwater. Sequential UV aging after BSA coating caused protein denaturation, reducing the stability of NPs. Additionally, increased temperatures led to a greater level of NP aggregation due to lower energy barriers. These findings highlight UV aging, protein coating, and temperature as critical factors influencing the behavior and fate of NPs in natural environments.

Microscopic Heterogeneity Driven by Molecular Aggregation and Water Dynamics in Aqueous Osmolyte Solutions.

Water dynamics are investigated in binary osmolyte-water mixtures, exhibiting a microscopic heterogeneity driven by molecular aggregation, on the basis of molecular dynamics (MD) simulation studies. The protecting osmolyte TMAO molecules in solution are evenly dispersed without the formation of noticeable osmolyte aggregates, while the denaturant TMU molecules aggregate readily, generating microscopic heterogeneity in the spatial distribution of component molecules in TMU-water mixtures. A combined study of MD simulation with graph theoretical analysis and spatial inhomogeneity measurement with h-values in the two osmolyte solutions revealed that the translational and rotational motions of water in the microheterogeneous environment of TMU-water mixtures are less hindered than those in the homogeneous media of TMAO-water mixtures. The analysis of the osmolyte-water H-bond lifetime in the binary solutions shows that destabilizing osmolyte TMU makes relatively weak osmolyte-water interaction, compared to that in protecting osmolyte TMAO, enabling the interplay of TMU-TMU or TMU-protein as well as TMU-water interaction. Taken together, the complementary contributions of the two hypotheses are proposed to elucidate the operating mechanism of the osmolyte on protein stability, encompassing a direct mechanism for the preferential interaction between the osmolyte and protein and an indirect mechanism for the modulation of the water structure and dynamics in the osmolyte solutions.

Confined active area and aggregation kinetic-based AuNPs@PVP nanosensors for simultaneous colorimetric detection of cysteine and homocysteine as homologues in human urine and serum.

The detection of cysteine (Cys) and homocysteine (Hcy) in biological fluids has great significance for early diagnosis, including Alzheimer's and Parkinson's disease. Thesimultaneous determination of Cys and Hcywith a single probe is still a huge challenge. Toenlarge the differences in space structure (line and ring) and energy (-721.78 and -761.08 Hartree) between Cys and Hcy, and to causeadifference of aggregation kinetics, gold nanoparticles (AuNPs) are capped with hydrophilic and low-toxic polyvinylpyrrolidone (PVP) (namedAuNPs@PVP) andsome surface-active sites of AuNPs are masked, the active area for the binding between AuNPs and the detection object is confined, meanwhile, the stability of AuNPs is improved. A novel nanosensorbased on confined active area and aggregation kinetics of AuNPs@PVP, is designed for the identification and determination of Cys and Hcy in 1 and 3min, respectively, with sufficiently lowdetection limit (4.12 and 4.35μM) and linear range (4.12-100μM) for health evaluation. This single colorimetric sensor wasapplied successfully tothe determination of urine and serum, evidencing highanti-interference ability.

Effect of colloidal particle size on physicochemical properties and aggregation behaviors of two alkaline soils

Abstract. Colloidal particles are the most active soil components, and they vary in elemental composition and environmental behaviors with the particle size due to the heterogeneous nature of natural soils. The purposes of the present study are to clarify how particle size affects the physicochemical properties and aggregation kinetics of soil colloids and to further reveal the underlying mechanisms. Soil colloidal fractions, from two alkaline soils – Anthrosol and Calcisol – were subdivided into three ranges: d<2 µm, d<1 µm and d<100 nm. The organic and inorganic carbon contents, clay mineralogy and surface electrochemical properties, including surface functional groups and zeta potentials, were characterized. Through a time-resolved light scattering technique, the aggregation kinetics of soil colloidal fractions were investigated, and their critical coagulation concentrations (CCCs) were determined. With decreasing colloidal particle diameter, the total carbon content, organic carbon, organic functional groups' content and illite content all increased. The zeta potential became less negative, and the charge variability decreased with decreasing particle diameter. The CCC values of Anthrosol and Calcisol colloids followed the descending order of d<100 nm, d<1 µm and d<2 µm. Compared with the course factions (d<1 and d<2 µm), soil nanoparticles were more abundant in organic carbon and more stable clay minerals (d<100 nm); thus they exhibited strongest colloidal suspension stability. The differences in organic matter contents and clay mineralogy are the fundamental reasons for the differences in colloidal suspension stability behind the size effects of Anthrosol and Calcisol colloids. The present study revealed the size effects of two alkaline soil colloids on carbon content, clay minerals, surface properties and suspension stability, emphasizing that soil nanoparticles are prone to be more stably dispersed instead of being aggregated. These findings can provide references for in-depth understanding of the environmental behaviors of the heterogeneous soil organic–mineral complexes.

Low‐Cost, High‐Efficiency Organic Solar Cells Based on Ecofriendly Processing Solvent

Developing organic photovoltaic materials at low‐cost and processing with eco‐friendly solvents are promising strategies to solve the critical issues of organic photovoltaic. Key hurdles for commercialization are synthetic complexity of the donor and the prevalent casting from hazardous solvents. Herein, by choosing PTQ10 as a low‐complexity donor and optimizing PTQ10:BTP‐eC9 and PTQ10:Y6 devices cast from chloroform (CF) and o‐xylene (XY), we demonstrate excellent performance with the eco‐friendly solvent XY relative to the CF standard. We find the XY‐processed devices exhibit a PCE of 16.53%, which is higher than the CF‐processed OSCs (16.39%) and it is one of the highest values among PTQ10‐based binary systems. Furthermore, we investigated the adaptability in fabricating large‐area devices via the blade‐coating method. By using CF and XY solvents in 1 cm2 devices, a PCE of 14.94% for XY‐solvent and 12.86% for CF‐solvent was achieved. We further studied the aggregation kinetics by time‐resolved in situ UV‐Vis absorbance measurements to understand differences in bulk heterojunction formation. We observe an overall longer time with XY over CF that improves the reproducibility with XY. We successfully transitioned from toxic solvents to eco‐friendly alternatives without sacrificing efficiency, combined with a low‐cost donor polymer, advancing future practical and commercial applications.

Effect of Lipidation on the Structure, Oligomerization, and Aggregation of Glucagon-like Peptide 1.

Lipidated analogues of glucagon-like peptide 1 (GLP-1) have gained enormous attention as long-acting peptide therapeutics for type 2 diabetes and also antiobesity treatment. Commercially available therapeutic lipidated GLP-1 analogues, semaglutide and liraglutide, have the great advantage of prolonged half-lives in vivo of hours and days instead of minutes as is the case for native GLP-1. A crucial factor in the development of novel lipidated therapeutic peptides is their physical stability, which greatly influences manufacturing and drug product development. This work provides a systematic study of the solubility, structure, oligomerization, and long-term stability of five different lipidated analogues of GLP-1, varying in the position of the lipidation site and the nature of lipid attachment. The lipidation was found to negatively impact the peptide solubility, in all cases, limiting it to a specific pH range. An increase in the α-helical secondary structure was observed upon lipidation, and the lipidated analogues were found to form larger and more stable oligomeric species compared to nonlipidated GLP-1. Importantly, the distributions and populations of oligomeric species formed were regulated by both the position and the nature of the lipidation. During the 6 days of sample aging, several lipidated analogues formed aggregates with variable morphologies ranging from elongated mature fibrils to amorphous structures. The kinetics of aggregation often showed multiple steps and did not follow a standard nucleation-propagation mechanism. A wide range of behaviors was observed, and while our observations indicate that the formation of a single stable oligomer results in the greatest physical stability, positioning the lipid group toward the N-terminus of the peptide results in extremely rapid amyloid formation. We believe that our study provides important findings for the development of long-acting lipidated analogues of peptide therapeutics.

Charge Modification of Lysine Mitigates Amyloid-β Aggregation.

Alzheimer's disease (AD) is a progressive neurodegenerative condition characterized by the deposition of amyloid-β (Aβ) peptides, which aggregate into toxic structures such as oligomers, fibrils, and plaques. The presence of these Aβ aggregates in the brain plays a crucial role in the pathophysiology, leading to synaptic dysfunction and cognitive impairment. Understanding how physiological factors affect Aβ aggregation is essential, and therefore, exploring their influence in vitro will likely provide insights into their role in AD pathology. In this study, we investigated the effects of physiological, free amino acids on Aβ aggregation dynamics. We focused on positively charged amino acids, particularly lysine, and employed a chemical modification, methylation, to neutralize its charge. Our analyses revealed that modified lysine significantly reduced Aβ aggregation, indicating that charge distribution of amino acids plays a crucial role in modulating Aβ aggregation behavior. These findings enhance our understanding of the regulatory factors influencing Aβ aggregation and highlight important considerations for future research on Aβ.

Nonbonded Molecular Interaction Controls Aggregation Kinetics of Hydrophobic Molecules in Water.

Molecular aggregation frequently occurs during material synthesis, cellular processes, and drug delivery systems, often resulting in decreased performance and efficiency. One major reason for such aggregation in an aqueous solution is hydrophobicity. While the basic understanding of the aggregation process of hydrophobic molecules from a thermodynamic standpoint is known, the present literature lacks a connection between the aggregation kinetics and the molecular basis of hydrophobicity. This study explores how various fluorescent probes (rhodamine dyes) aggregate in an aqueous solution due to their hydrophobicity. The method employs a combination of modeling and characterization to comprehend the aggregation process by examining the nonbonded intermolecular interactions. The aggregation kinetics was analyzed by measuring the average diffusivity of the molecules using fluorescent correlation spectroscopy and NMR diffusion measurements. Through all-atom molecular dynamics (MD) simulations, it has been observed that the level of hydrophobicity is strongly correlated to the total number of hydrogen bonds between water molecules and dyes. In addition, the aggregation frequency of colliding species, which depends on the concentration, is inversely related to hydrogen bonding and the diffusivity of the molecules. This study of small molecules was applied to predict protein aggregation rates, demonstrating strong alignment with the existing literature. The study has also helped to identify and understand the concentration at which a hydrophobic molecule does not aggregate in an aqueous solution. The method developed here could help investigate the aggregation process and its root causes at the molecular level in aqueous systems to develop strategies to control it.

Molecular foundations for shear-induced dynamics of natural organic matter.

The overall objective of the present work was to quantify how shear, coupled with varying salt concentration, affected the particle size distribution and relaxation/aggregation behavior for various organic sources of nonliving natural organic matter (NNOM) in surface water. NNOM has been implicated as a conditioning agent leading to the formation of biofilms such as algae. NNOM is also a responsible in surface waters for facilitated transport of a variety of anthropogenic pollutants. These are NNOM surface-related phenomena, yet the variable surface area and surface composition of NNOM, which can change dependent on shear rate, is not discussed in the literature. NNOM polymer-like dynamics can interact with stream water velocity differences to determine the process and result of aggregation. The fundamental role of post-shear NNOM molecular structure and dynamic aggregation (self-assembly) is examined here alongside fresh (hydrological) versus mined (terrestrial) NNOM. Shear rate can be seen as a change in the velocities of streamlines in hydrology. In this early work, the response to shear rate for three types of NNOM was measured using a stress-controlled rheometer under varying conditions of ionic strength. Samples were studied for rheological response after a variety of pre-shear conditions, and data then coupled with surface composition data from previously reported fluorescence studies. Interestingly, a size class of 5μm aggregates disappeared when Aldrich humic acid samples were treated with 0.3M Ca2+. Evidence is also presented that the environmental samples flocculated at shear rates up to 400s-1, rather than exhibiting particle breakup, with implications for reducing NNOM surface area. Dynamic response of different NNOM sources was not the same, some sources showing evidence of self-assembly. The molecular response to shear may play an important role in understanding the surface area and composition of NNOM responsible for facilitated transport of pollutants and initiation of biofilms.

Natural Organic Matter Stabilizes Pristine Nanoplastics but Destabilizes Photochemical Weathered Nanoplastics in Monovalent Electrolyte Solutions.

Photochemical weathering and eco-corona formation through natural organic matter (NOM) adsorption play vital roles in the aggregation tendencies of nanoplastics (NPs) in aquatic environments. However, it remains unclear how photochemical weathering alters the adsorption patterns of NOM and the conformation of the eco-corona, subsequently affecting the aggregation tendencies of NPs. This study examined the effect of Suwannee River NOM adsorption on the aggregation kinetics of pristine and photoaged polystyrene (PS) NPs in monovalent electrolyte solutions. The results showed that photochemical weathering influenced the conformation of the eco-corona, which, in turn, determined NP stability in the presence of NOM. Hydrophobic components of NOM predominantly bound to pristine NPs through hydrophobic and π-π interactions, and extended hydrophilic segments in water hindered NP aggregation via steric repulsion. Conversely, hydrogen bonding facilitated the binding of these hydrophilic segments to multiple photoaged NPs, thereby destabilizing them through polymer bridging. Additionally, the stabilization and destabilization capacities of NOM increased with its concentration and molecular weight. These findings shed light on the destabilizing role of NOM in weathered NPs, offering new perspectives on environmental colloidal chemistry and the fate of NPs in complex aquatic environments.

Human serum albumin-3-amino-1-propanesulfonic acid conjugate inhibits amyloid-β aggregation and mitigates cognitive decline in Alzheimer's disease.

Alzheimer's disease (AD) is the most commonly occurring brain disorder, characterized by the accumulation of amyloid-β (Aβ) and tau, subsequently leading to neurocognitive decline. 3-Amino-1-propanesulfonic acid (TPS) and its prodrug, currently under clinical trial III, serve as promising therapeutic agents targeting Aβ pathology by specifically preventing monomer-to-oligomer formation. Inspired by the potency of TPS prodrug, we hypothesized that conjugating TPS with human serum albumin (HSA) could enhance brain delivery and synergistically inhibit Aβ aggregation in mild to moderate AD. Thus, we prepared and extensively characterized HSA-TPS (h-TPS) conjugate using an eco-friendly coupling method. In vitro studies on Aβ aggregation kinetics and AFM imaging revealed significant prevention of Aβ aggregation. Additionally, h-TPS significantly reduced Aβ-induced neurotoxicity and H2O2-mediated reactive oxygen species (ROS) stress in SH-SY5Y cells. Moreover, h-TPS administration improved blood-brain barrier permeability and cellular uptake into neuronal cells as well as showed in vivo uptake inside the brain within 1 h. In vivo studies using an Aβ1-42-induced acute AD rat model exhibited a dose-dependent significant reduction in hippocampal Aβ levels and restoration of declined spatial learning and memory with h-TPS treatment. Overall, findings suggest that h-TPS conjugate might be a promising neuroprotective agent for preventing Aβ aggregation in mild to moderate AD.

Excited-State Carrier Dynamics in Semiconducting Heterostructures from Self-Sorted NIR Active Dyes.

Heterostructures comprise two or more different semiconducting materials stacked either as co-assemblies or self-sorted based on their dynamics of aggregates. However, self-sorting in heterostructures is rather significant in improving the short exciton diffusion length and charge separation. Despite small organic molecules being known for their self-sorting nature, macrocyclic are hitherto unknown owing to unrestrained assemblies from extended π-conjugated systems. Herein, two near infrared region (NIR) active molecules comprised of porphyrin appended D-π-D (1) and A-π-A (2) have been reported to show the self-assembled 0D and 2D nanostructures via J-aggregates. Interestingly, the mixture of 1 and 2 reveals self-sorting at the molecular level promoting nanosphere and sheet structures which further rolled over to spheres through π-π stacking leading to core-shell type heterostructure. Consequently, electrical conductivity is 10 times higher than the individual assemblies due to excited state electron transfer from 1 to 2 in a mixture, confirmed by femto second-transient absorption spectroscopy and electrochemical impedance spectroscopy. These results suggest that controlling the self-sorted heterostructures fosters refining the electronic properties which pave the way for designing novel NIR-absorbed molecules for organic solar cells (OSCs).

Helical Assemblies of Colloidal Nanocrystals with Long-Range Order and Their Fusion into Continuous Structures.

Chirality epitomizes the sophistication of chemistry, representing some of its most remarkable achievements. Yet, the precise synthesis of chiral structures from achiral building blocks remains a profound and enduring challenge in synthetic chemistry and materials science. Here, we demonstrate that achiral colloidal nanocrystals, including Au and Ag nanocrystals, can assemble into long-range-ordered helical assemblies with the assistance of chiral molecules. The synchronized aggregation kinetics between colloidal silver or gold nanocrystals and π-conjugated perylene diimide molecules enables the nanocrystals to precisely follow the helical pathways of the molecular assemblies. This results in the formation of helical nanocrystal assemblies extending over tens of micrometers. These helically organized nanocrystals, exhibiting high positional precision, display linear size-dependent chiroptical properties. Furthermore, more intricate helical assemblies, featuring triple, quadruple, and quintuple nanocrystal strands, can be observed in addition to the commonly encountered double helical assemblies. Finally, these helical assemblies, composed of discrete Ag nanocrystals, can fuse into continuous Ag2S helical structures following a sulfidation reaction, ultimately leading to the formation of diverse metal sulfide helices through cation exchange processes.