Controlling lamination and directional growth of ß-sheets via hydrophobic interactions: The strategies and insights.

The self-assembling morphologies of proteins, nucleic acids, and peptides are well correlated with their functioning in biological systems. In spite of extensive studies for the morphologies regulating, the directional control of the assembly morphology structure for the peptides still remains challenging. Here, the directional structure control of a bola-like peptide Ac-KIIF-CONH2 (KIIF) was realized by introducing different amount of acetonitrile to the system. The morphologies were characterized by transmission electron microscopy (TEM) and atomic force microscopy (AFM), and the secondary structure was evaluated by circular dichroism (CD) and Fourier transform infrared spectroscopy (FTIR). The results demonstrated that the introducing of different amount of acetonitrile has significantly tuned the hydrophobic interactions amongst the side chains, thus affecting the self-assembling morphologies. As acetonitrile content increased, the assemblies changed from nanotubes to helical/twisted ribbons and then to thin fibrils, with a steady decrease in the width. In contrast, the assemblies changed from thin fibrils to helical/twisted ribbons, and then to matured nanotubes, exhibiting a steady increase in the width with peptide concentration increasing. Complementary molecular dynamics (MD) simulations demonstrated the important role of acetonitrile in controlling the hydrophobic interactions, providing microscopic evidence for the structure transition process. We believe such observations provide important insights into the design and fabrication of functional materials with controlled shape and size.

Dual role of triglyceride structures facilitates anti-tumor drug delivery: Both as a self-assembling module and a responsive module.

Small molecule prodrugs self-assembled nano-delivery systems with tumor responsive linkages are emerging as an effective platform. However, the heterogeneity of tumor microenvironment may limit the anti-tumor effect of prodrug nanomedicines with a single response module. Here, we chose disulfide bond as the response module and branched chain alcohol as the self-assembly modification module to construct a single-responsive prodrug. We also constructed a double-responsive paclitaxel prodrug combining triglyceride and disulfide bond, taking into account of the highly expressed lipase and glutathione levels in tumor cells. The results showed that the anti-tumor effect of single-responsive branched chain alcohol modified prodrug nanoparticles was inferior to triglyceride prodrug nanoparticles with dual response modules. The triglyceride structure can not only serve as a self-assembly modification module, but also serve as a response module for intelligent drug release in tumor. Such dual roles will facilitate the efficient delivery of small molecule self-assembled prodrugs to tumor sites.

Hydrogen bond-induced supramolecular self-assembly strategy to fabricate ultra-dispersed Cu-loaded porous tubular graphitic carbon nitride with rich nitrogen vacancies and CuNx sites for efficient photo-Fenton catalysis.

The low utilization of visible light and easy recombination of charge carriers of graphitic carbon nitride (CN) restrain its application as photo-electron donor and metal site support in photo-Fenton system. Herein, a hydrogen bond-induced supramolecular self-assembly strategy was created to fabricate an ultra-dispersed Cu-loaded porous tubular CN composite (CA-Cu/TCN) by the hydrothermal-pyrolysis method with citric acid (CA) as initiator and chelating agent. CA-Cu/TCN with rich nitrogen vacancies (NVs) and abundant ultra-dispersed CuNx sites exhibited narrow bandgap, favorable visible light absorption capability, and high separation and transfer efficiency of charge carriers. CA-Cu/TCN effectively catalyzed the activation of H2O2 for generating abundant reactive oxygen species under visible light irradiation, contributing to efficient degradation of ciprofloxacin (CIP) with removal rate of 95.9 % and kinetic rate constant of 0.0948 min-1. The superior catalytic activity of CA-Cu/TCN can be ascribed to the effective transport of photogenerated electrons, high specific surface area, atomically dispersed Cu species, and enriched surface NVs. The mechanism of photo-Fenton catalytic degradation of CIP and possible degradation pathways were proposed as the dominant role of 1O2. Toxicity evaluation of CIP and intermediates indicated that the degradation of CIP was a gradual detoxification process. This work offers a novel self-assembly strategy to design and synthesize highly active and sustainable visible light-driven photo-Fenton catalysts for effectively degrading organic pollutants.

CO2 induced phase transition on a self-standing droplet studied by X-ray scattering and magnetic resonance.

HYPOTHESIS: Acoustic levitation is a suitable approach for studying processes occurring at the gas-liquid interfaces, as it allows its investigation in a contact-free manner while providing control over the gas phase. Here, we hypothesize that phase transitions induced by a CO2 rich atmosphere can be examined, at different length scales, in a contact-free manner. EXPERIMENTAL: A system consisting of 12-hydroxysteric acid (HSA) soaps mixed with different ratios of monoethanolamine (MEA) and choline hydroxide, was prepared. Microliter droplets of the samples were acoustically levitated and monitored with a camera, while exposed to CO2 to modify the pH through diffusion at the air-liquid interface and inside the droplet. The phase transition and water mobility in the levitated droplets were evaluated through X-ray scattering (SAXS/WAXS) and magnetic resonance studies, in real-time. Finally, the droplets were collected and examined under the microscope. FINDINGS: The introduction of CO2 gas induced a phase transition from micelles to multi-lamellar tubes, resulting in a gel-like behavior both in the bulk and at the interface. The high stability of the acoustic levitator allowed the investigation of this dynamic phenomenon, in real-time, in a contact-free environment. This study showcases the suitability of acoustic levitation as a tool to investigate complex chemical processes at interfaces.

Emulsions stabilized by phospholipids.

HYPOTHESIS: Phospholipids are amphiphilic molecules able to adsorb at oil/water interfaces and thus used to stabilize parenteral emulsions. Yet, their low preferred curvature, which sensitively depends on molecular structures and interactions, favors the formation of lamellar phases and sets constraints on the system formulation. Combining phase studies, structural interfacial characterizations, and stability monitoring for different water/phospholipid/oil systems should shine a light on the mechanisms at play and thus tools to optimize formulations. EXPERIMENTS: Four phase diagrams were established for ternary aqueous systems containing either DOPC or POPC as the phospholipid and hexadecane or miglyol 812 as the oil. Droplet interfaces were probed using small-angle neutron scattering and the amount of adsorbed lipid was determined using separation and Raman spectroscopy. The metastability of both nano and macro emulsions was systematically assessed over weeks using light scattering. FINDINGS: We show that nanoemulsion droplets are stabilized by a lipid monolayer and display excellent metastability if the preferred curvature is positive and large enough, even without any added charges or at high ionic strengths. In contrast, macroemulsion droplets are stabilized with a lipid multilayer, which should possess a positive preferred curvature but also a good enough interfacial anchorage, which is lost upon increasing the preferred curvature. Overall, we provide a rationale for understanding the impact of molecular changes in the formulation on emulsion metastability, through the analysis of the lipid film preferred curvature, layering, and interfacial anchorage.

DNA self-assembly-boosted transcription amplification coupled with CRISPR/Cas13a system for plant microRNA analysis.

MicroRNAs (miRNAs) play important roles in the growth process of plants, and some food-originated plant miRNAs have potential impacts on human health, which makes the detection of plant miRNAs of great significance. However, plant miRNAs are naturally modified with 2'-O-methyl at the 3'-terminal, which is difficult to be directly quantified by enzyme-catalyzed terminal polymerization protocols. Herein, we have proposed a simple strategy by coupling DNA self-assembly-boosted transcription amplification with CRISPR/Cas13a platform (termed as Cas13a-SATA) for the specific and sensitive detection of plant miRNA. In the Cas13a-SATA, the plant miRNA will mediate DNA self-assembly on the surface of microbeads and then trigger efficient transcription amplification to yield numerous single-stranded RNA (ssRNA) molecules, which can effectively activate the Cas13a trans-cleavage activity to generate intense fluorescence signal in a plant miRNA dosage-responsive manner. Using the Cas13a-SATA, we have realized the sensitive detection of plant miR156a with the limit of detection (LOD) down to 3.8 fM. Furthermore, Cas13a-SATA has been successfully applied to the accurate quantification of miR156a in Arabidopsis and maize, demonstrating its feasibility in analyzing plant miRNAs in real biological samples.

Self-assembled high-entropy Prussian blue analogue nanosheets enabling efficient sodium storage.

High entropy material (HEM) has emerged as an appealing material platform for various applications, and specifically, the electrochemical performances of HEM could be further improved through self-assembled structure design. However, it remains a big challenge to construct such high-entropy self-assemblies primarily due to the compositional complexity. Herein, we propose a bottom-up directional freezing route to self-assemble high-entropy hydrosols into porous nanosheets. Taking Prussian blue analogue (PBA) as an example, the simultaneous coordination-substitution reactions yield stable high-entropy PBA hydrosols. During subsequent directional freezing process, the anisotropic growth of ice crystals could guide the two-dimensional confined assembly of colloidal nanoparticles, resulting in high-entropy PBA nanosheets (HE-PBA NSs). Thanks to the high-entropy and self-assembled structure design, the HE-PBA NSs manifests markedly enhanced sodium storage kinetics and performances in comparison with medium/low entropy nanosheets and high entropy nanoparticles.

Influence of critical micelle concentration of choline-based long chain fatty acid soaps on their antibacterial activity against Methicillin resistant Staphylococcus aureus.

HYPOTHESIS: Antimicrobial resistance (AMR) is a pressing global health concern. ESKAPEE pathogens, such as Methicillin-resistant Staphylococcus aureus (MRSA) are notable of concern in healthcare settings due to their resistance to critical antibiotics. To combat AMR, the development of alternatives such as bacterial membrane-active agents is crucial. Fatty acids (FAs) have emerged as a sustainable, antibiotic-free solution with inherent antibacterial activity. However, long chain saturated fatty acids (LCFAs) sodium soaps exhibit poorly antibacterial properties in comparison to short chain FAs, believed to be linked to limited solubility in aqueous media. EXPERIMENTS: We employed choline as a chaotropic organic counter-ion to enhance the solubility of LCFAs and investigated their antibacterial effects against MRSA. The optimal medium conditions for micelle formation for LCFAs was first investigated. Then, we determined the critical micelle concentration (CMC), micellar morphology, and aggregation number through surface tension measurements and small angle neutron scattering experiments. Antimicrobial activity was assessed using minimum bactericidal concentration (MBC) assays and time-kill experiments. FINDINGS: We have identified conditions where LCFAs are effective against MRSA for the first time, providing valuable insights for developing new antibacterial agents to fight AMR. LCFAs need to be used above their Krafft temperatures and CMC to exhibit antibacterial efficacy.

Microtube self-assembly leads to conformational freezing point depression.

HYPOTHESIS: Multi-walled tubular aggregates formed by hierarchical self-assembly of beta-cyclodextrin (ß-CD) and sodium dodecylsulfate (SDS) hold a great potential as microcarriers. However, the underlying mechanism for this self-assembly is not well understood. To advance the application of these structures, it is essential to fine-tune the cavity size and comprehensively elucidate the energetic balance driving their formation: the bending modulus versus the microscopic line tension. EXPERIMENTS: We investigated temperature-induced changes in the hierarchical tubular aggregates using synchrotron small-angle X-ray scattering across a broad concentration range. Detailed analysis of the scattering patterns enabled us to determine the structural parameters of the microtubes and to construct a phase diagram of the system. FINDINGS: The microtubes grow from the outside in and melt from the inside out. We relate derived structural parameters to enthalpic changes driving the self-assembly process on the molecular level in terms of their bending modulus and microscopic line tension. We find that the conformation of the crystalline bilayer affects the saturation concentration, providing an example of a phenomenon we call conformational freezing point depression. Inspired by the colligative phenomenon of freezing point depression, well known from undergraduate physics, we model this system by including the membrane conformation, which can describe the energetics of this hierarchical system and give access to microscopic properties without free parameters.

The assembly mechanism of Zein/EGCG/PEG nanoparticles in a water system and their adsorption behavior at the oil-water interface.

In this study, the self-assembly mechanism of Zein/(-)-epigallocatechin-3-gallate/polyethylene glycol (Zein/EGCG/PEG) composite nanoparticles and their interface adsorption behavior at the oil-water interface were investigated by coarse-grained molecular dynamics simulation. Fourier transform infrared spectroscopy and conformation analysis demonstrated that there were electrostatic and hydrogen bond interactions between Zein and EGCG, physical entanglement between PEG and Zein, and hydrogen bond interaction between EGCG and PEG. The nanoparticles accumulated at the oil-water interface, and there was an obvious interface layer between oil phase and water phase, as indicated by confocal laser scanning microscope and scanning electron microscope. The adsorbing of Zein/EGCG/PEG nanoparticles at the oil-water interface was confirmed by coarse-grained molecular dynamics simulation. Further findings confirmed that Zein/EGCG/PEG nanoparticles could serve as stabilizers for oleogels with self-supporting structure, viscoelastic solid behavior and temperature response characteristics. The current research offered a novel approach to enhance protein interface characteristics and create food-grade emulsifiers and oleogelators.

Self-assembly of mixed-linkage glucan hydrogels formed following EG16 digestion.

Mixed-linkage glucans are major components of grassy cell-walls and cereal endosperm. Recently identified plant endo-ß-glucanase from the EG16 family cleaves MLGs with strong specificity towards regions with at least four sequential ß(1,4)-linked glucose residues. This activity yields a low molecular-weight MLG with a repeating structure of ß(1,3)-linked cellotriose that gels rapidly at concentrations as low as 1.0 % w/v. To understand the gelation mechanism, we investigated the structure and behavior using rheology, microscopy, X-ray scattering, and molecular dynamics simulations. Upon digestion, the material's rheological behavior changes from typical polymeric material to a fibrillar network behavior seen for e.g. cellulose nanofibrils. Scanning electron microscopy and confocal microscopy verifies these changes in micro- and nanostructure. Small-angle X-ray scattering shows in-solution self-assembly of MLG through ~10 nm elemental structures. Wide-angle X-ray scattering data indicate that the polymer association is similar to cellulose II, with dominant scattering at d-spacing of 0.43 nm. Simulations of two interacting glucan chains show that ß(1,3)-linkages prevent the formation of tight helices that form between ß(1,4)-linked d-glucan chains, leading to weaker interactions and less ordered inter-chain assembly. Overall, these data indicate that digestion drives gelation not by enhancement of interactions driving self-assembly, but by elimination of unproductive interactions hindering self-assembly.

Supramolecular assembly strategy of modified starch chains for achieving recyclable emulsion biocatalysis within a narrow pH range.

Stimuli-responsive Pickering emulsions are promising in biocatalysis for their ease of product separation and emulsifier recovery. However, pH responsiveness, though simple and cost-effective, faces challenges in precise control and narrow transition ranges, limiting its use in enzymatic catalysis. Herein we introduced amorphous octenyl succinic anhydride-modified debranched starch chains (Am-OSA-St) to control emulsion properties within a pH range suitable for enzymatic catalysis. By adjusting the OSA group density and molecular weight, Am-OSA-St allowed emulsions to transition reversibly between pH 7.3 and 5.5 and enabled self-recycling through supramolecular self-assembly. Employing molecular dynamics simulations and physicochemical characterization, we elucidated the control mechanism of oil-water interfaces via the microstructure transformation of Am-OSA-St. The findings revealed that protonation of carboxylate groups disrupted the charge balance and polarity of starch chains, leading to strong electrostatic and van der Waals interactions that drove self-assembly. This entanglement caused starch chains in the aqueous phase to "drag" those at the oil-water interface, moving them into the aqueous phase and forming micelles. These micelles, with a hydrophobic interior and hydrophilic exterior, prevented re-adsorption. Testing with Candida antarctica Lipase B (CALB) and N-acetylneuraminic lyase showed that the pH-regulated emulsion system maintained excellent efficiency and cycling stability in mild conditions.

Tunable supramolecular self-assemblies based on cyclodextrin polymer as a loading platform for water-soluble drugs.

Drug loading capacity is a crucial character of nano-scaled drug carriers to achieve high quality pharmaceutical preparations. However, efficient encapsulation of water-soluble small molecular drugs still faces large obstacles in many cases. Herein, we designed a novel supramolecular delivery system constructed by poly(ß-cyclodextrin) containing benzoic acid groups (PCD-PA) and adamantyl terminated poly(ethylene glycol) (PEG-AD) to provide multiple intermolecular interactions for competent loading of water-soluble small-molecular drugs. PCD-PA had multiple host molecules, and PEG-AD could be inserted via host-guest interaction in different proportion to adjust the composition of supramolecular carrier. Meanwhile, π-π stacking and electrostatic interaction furnished by benzoic acid groups served as binding force for drug entrapment, which led to considerable loading capacity for several water-soluble drugs. Among the drugs with different chemical structures, mitoxantrone hydrochloride and doxorubicin hydrochloride bearing anthraquinone rings and several protonable amino groups acquired the highest loading content as about 14 % in PCD-PA3/PEG-AD supramolecular self-assemblies. Further computational simulations investigated the mechanism of drug loading based on the interactions between the carrier materials and the payloads. In addition, the weakly acidic environment obviously accelerated the release of certain drugs. All in all, this self-assembled supramolecular nano-system displayed great potentials as a delivery platform for diverse water-soluble drugs.

The force of Zein self-assembled nanoparticles and the application of functional materials in food preservation.

Zein self-assembled nanoparticles (Z-NPs) are an excellent delivery carrier for bioactive components. However, the poor stability of its application in the food industry is the main problem. This paper focused on the self-assembly force of Z-NPs and the factors affecting the stability of Z-NPs. Meanwhile, the modification methods of zein and its interaction with food additives were analyzed. Additionally, its application in the field of food preservation was reviewed. The main interactions between zein and polyphenols encompass hydrogen bonding, non-covalent interactions, and hydrophobic interactions. Besides, the interactions with polysaccharides involve both covalent and non-covalent interactions. Furthermore, the protein interactions entail hydrophobic interactions, electrostatic interactions, hydrogen bonds, and π-π stacking. The primary driving forces governing zein self-assembly encompass electrostatic interactions, hydrogen bonding, van der Waals forces, hydrophobic interactions, and π-π stacking. Meanwhile, functionalized Z-NPs can be used in the food preservation industry to prolong the shelf life of food.

Artificial chemotaxis under electrodiffusiophoresis.

HYPOTHESIS: Through a large parameter space, electric fields can tune colloidal interactions and forces leading to diverse static and dynamical structures. So far, however, field-driven interactions have been limited to dipole-dipole and hydrodynamic contributions. Nonetheless, in this work, we propose that under the right conditions, electric fields can also induce interactions based on local chemical fields and diffusiophoretic flows. EXPERIMENTS: Herein, we present a strategy to generate and measure 3D chemical gradients under electric fields. In this approach, faradaic reactions at electrodes induce global pH gradients that drive long-range transport through electrodiffusiophoresis. Simultaneously, the electric field induces local pH gradients by driving the particle's double layer far from equilibrium. FINDINGS: As a result, while global pH gradients lead to 2D focusing away from electrodes, local pH gradients induce aggregation in the third dimension. Evidence points to a mechanism of interaction based on diffusiophoresis. Interparticle interactions display a strong dependence on surface chemistry, zeta potential and diameter of particles. Furthermore, pH gradients can be readily tuned by adjusting the voltage and frequency of the electric field. For large Péclet numbers, we observed a collective chemotactic-like collapse of particles. Remarkably, such collapse occurs without reactions at a particle's surface. By mixing particles with different sizes, we also demonstrate, through experiments and Brownian dynamics simulations, the emergence of non-reciprocal interactions, where small particles are more drawn towards large ones.

Kinetic monitoring of molecular interactions during surfactant-driven self-propelled droplet motion by high spatial resolution waveguide sensing.

HYPOTHESIS: Self-driven actions, like motion, are fundamental characteristics of life. Today, intense research focuses on the kinetics of droplet motion. Quantifying macroscopic motion and exploring the underlying mechanisms are crucial in self-structuring and self-healing materials, advancements in soft robotics, innovations in self-cleaning environmental processes, and progress within the pharmaceutical industry. Usually, the driving forces inducing macroscopic motion act at the molecular scale, making their real-time and high-resolution investigation challenging. Label-free surface sensitive measurements with high lateral resolution could in situ measure both molecular-scale interactions and microscopic motion. EXPERIMENTS: We employ surface-sensitive label-free sensors to investigate the kinetic changes in a self-assembled monolayer of the trimethyl(octadecyl)azanium chloride surfactant on a substrate surface during the self-propelled motion of nitrobenzene droplets. The adsorption-desorption of the surfactant at various concentrations, its removal due to the moving organic droplet, and rebuilding mechanisms at droplet-visited areas are all investigated with excellent time, spatial, and surface mass density resolution. FINDINGS: We discovered concentration dependent velocity fluctuations, estimated the adsorbed amount of surfactant molecules, and revealed multilayer coverage at high concentrations. The desorption rate of surfactant (18.4 s-1) during the microscopic motion of oil droplets was determined by in situ differentiating between droplet visited and non-visited areas.

Insights into the Hierarchical Assembly of a Chemically Diverse Peptide Hydrogel Derived from Human Semenogelin I.

A peptide corresponding to a 13-residue segment of the human protein semenogelin I has been shown to generate a hydrogel consisting of amyloid-like fibrils. The relative chemical diversity (compared to synthetic de novo sequences) with 11 distinct amino acids makes this peptide (P0) an ideal candidate for investigating the role of individual residues in gelation. Herein, the N-terminal residues have been sequentially removed to furnish a series of truncated peptides, P1-P10, ranging from 12 to 3 residues in length. FTIR spectroscopy investigations reveal that P0-P6 forms a ß-sheet secondary structure while shorter sequences do not self-assemble. Site-specific isotope labeling of the amide backbone of P0-P2 with the IR-sensitive vibrational probe 13C═O yields FTIR spectra indicative of the initial formation of a kinetic product that slowly transforms into a structurally different thermodynamic product. The effects of the isotopic labels on the IR spectra facilitate the assignment of parallel and antiparallel structures, which are sometimes coexistent. Additional IR studies of three PheCN-labeled P0 sequences are consistent with an H-bonded ß-sheet amide core, spanning the 7 central residues. The macromolecular assembly of peptides that form ß-sheets was assessed by cryo-TEM, SAXS/WAXS, and rheology. Cryo-TEM images of peptides P1-P6 display µm-long nanofibrils. Peptides P0-P3 generate homogeneous hydrogels composed of colloidally stable nanofibrils, and P4-P6 undergo phase separation due to the accumulation of attractive interfibrillar interactions. Three amino acid residues, Ser39, Phe40, and Gln43, were identified to be of particular interest in the truncated peptide series as the removal of any one of them, as the sequence shortens, leads to a major change in material properties.

Self-Assembly of Metallo-Supramolecular Amphiphiles Based on Azadipyrromethenes: Consecutive Pathways to Nanodiscs and Nanosheets.

A new class of metallo-supramolecular amphiphilic dyes 1a, b was constructed by using two azadipyrromethene units which were respectively modified with two hydrophobic alkyl and two hydrophilic oligo(ethylene glycol) chains. The spectroscopic and morphological studies revealed the consecutive self-assembly pathways of 1a in EtOH/H2O mixed solvent. The monomers of 1a firstly aggregated into the kinetic-controlled, nanodisc-shaped Agg. I upon cooling and the latter spontaneously transformed into the thermodynamically more stable Agg. II with a nanosheet morphology. While the non-fluorescent Agg. I displayed a broad absorption band (λmax = 594 nm), the Agg. II displayed a more intensive and narrowed J-band (λmax =693 nm) and a fluorescence band with a maximum at 760 nm (Фfl = 0.1), which could be ascribed to the J-aggregation induced emission enhancement. The kinetics of Agg. I to Agg. II transformation was further modulated by seed-initiated supramolecular polymerization with various ratios of Seedagg.II, in which the transformation rate was significantly increased by ca. 2 orders of magnitude compared to the spontaneous process. The supramolecular amphiphile 1b bearing longer hydrophilic chains formed only one type aggregate, which exhibited spectroscopic and morphological properties that were highly comparable with that of Agg. I.

Photoregulated Supramolecular Polymerization through Halogen Bonding.

Supramolecular polymers are able to change their structure, morphology and function in response to external stimuli. However, controlling the independence of stimuli-responses in these systems is challenging. Herein, we exploit halogen bonding (XB) as a reversible network element to regulate the photoresponsive and adaptive behavior of supramolecular polymers. To this end, we have designed a system comprising an amphiphilic XB acceptor with the ability to self-assemble in aqueous media (OPE-Py) and a molecule with a dual photoresponsive and XB donor function [(E)-Azo-I]. OPE-Py self-assembles in aqueous media into supramolecular polymers, which transform into nanoparticle assemblies upon co-assembly with (E)-Azo-I. Interestingly, a third type of assembly (2D sheets) is obtained if OPE-Py is treated with (E)-Azo-I and exposed to photoirradiation. At ambient conditions, both nanoparticles and 2D sheets remain invariant over time. However, heating dissociates the XB interactions present in both assemblies, resulting in their transformation to the original fiber-like morphology of OPE-Py. Thus, breaking the communication between self-assembly and the stimuli-responses upon heating restores the original state of the system, drawing parallels to feedback loops in programming language. This work broadens the still limited scope of XB in solution assemblies and paves the way for multifunctional adaptive supramolecular systems.

Engineering of self-assembled silver-peptide colloidal nanohybrids with enhanced biocompatibility and antibacterial activity.

Several bacterial strains have developed resistance against commercial antibiotics, and interestingly, supramolecular nanomaterials have shown considerable advantages for antibacterial applications. However, the main challenges in adopting nanotechnology for antibacterial studies are random aggregation, compromised toxicity, multi-step preparation approaches, and unclear structure-function properties. Herein, we designed the amphiphilic tripeptide that acts as a reducing and capping agent for silver metal to form silver-peptide colloidal nanohybrids with the mild assistance of UV light (254 nm) through the photochemical reduction method. The nanohybrids are characterized by different spectroscopic and microscopic techniques, and non-covalent molecular interactions between metal and peptide building blocks confirm their central role in the formation of nanohybrids. The tripeptide is biocompatible and can reduce the toxicity of silver ions (Ag+) by reducing to Ag0. These colloidal nanohybrids showed antibacterial activity against gram-negative and gram-positive bacterial strains, and the possible mechanism of killing bacterial cells could be membrane disruption. This synthetic strategy is facile and green, which helps avoid using toxic chemicals or reagents and complicated methods for colloidal nanohybrid preparation for biomedical applications.