The organized assembly of particles into superstructures is typically governed by specific molecular interactions or external directing factors associated with the particle building blocks, both of ...which are particle-dependent. These superstructures are of interest to a variety of fields because of their distinct mechanical, electronic, magnetic and optical properties. Here, we establish a facile route to a diverse range of superstructures based on the polyphenol surface-functionalization of micro- and nanoparticles, nanowires, nanosheets, nanocubes and even cells. This strategy can be used to access a large number of modularly assembled superstructures, including core-satellite, hollow and hierarchically organized supraparticles. Colloidal-probe atomic force microscopy and molecular dynamics simulations provide detailed insights into the role of surface functionalization and how this facilitates superstructure construction. Our work provides a platform for the rapid generation of superstructured assemblies across a wide range of length scales, from nanometres to centimetres.
The development of antimicrobial drug resistance among pathogenic bacteria and fungi is one of the most significant health issues of the 21st century. Recently, advances in nanotechnology have led to ...the development of nanomaterials, particularly metals that exhibit antimicrobial properties. These metal nanomaterials have emerged as promising alternatives to traditional antimicrobial therapies. In this review, a broad overview of metal nanomaterials, their synthesis, properties, and interactions with pathogenic micro‐organisms is first provided. Secondly, the range of nanomaterials that demonstrate passive antimicrobial properties are outlined and in‐depth analysis and comparison of stimuli‐responsive antimicrobial nanomaterials are provided, which represent the next generation of microbiocidal nanomaterials. The stimulus applied to activate such nanomaterials includes light (including photocatalytic and photothermal) and magnetic fields, which can induce magnetic hyperthermia and kinetically driven magnetic activation. Broadly, this review aims to summarize the currently available research and provide future scope for the development of metal nanomaterial‐based antimicrobial technologies, particularly those that can be activated through externally applied stimuli.
Antimicrobial resistance remains a significant health issue. Recently, metal nanomaterials have emerged as promising antimicrobials. This review provides an overview of metal nanomaterials, detailing their synthesis, properties and antimicrobial activity. The antimicrobial mechanisms of these nanomaterials are discussed in the context of passive and stimuli‐responsive activity. The review summarizes this area of research and provides direction for future studies.
Abstract
A major health concern of the 21
st
century is the rise of multi-drug resistant pathogenic microbial species. Recent technological advancements have led to considerable opportunities for ...low-dimensional materials (LDMs) as potential next-generation antimicrobials. LDMs have demonstrated antimicrobial behaviour towards a variety of pathogenic bacterial and fungal cells, due to their unique physicochemical properties. This review provides a critical assessment of current LDMs that have exhibited antimicrobial behaviour and their mechanism of action. Future design considerations and constraints in deploying LDMs for antimicrobial applications are discussed. It is envisioned that this review will guide future design parameters for LDM-based antimicrobial applications.
Abstract
Catalytic solvent regeneration has attracted broad interest owing to its potential to reduce energy consumption in CO
2
separation, enabling industry to achieve emission reduction targets of ...the Paris Climate Accord. Despite recent advances, the development of engineered acidic nanocatalysts with unique characteristics remains a challenge. Herein, we establish a strategy to tailor the physicochemical properties of metal-organic frameworks (MOFs) for the synthesis of water-dispersible core-shell nanocatalysts with ease of use. We demonstrate that functionalized nanoclusters (Fe
3
O
4
-COOH) effectively induce missing-linker deficiencies and fabricate mesoporosity during the self-assembly of MOFs. Superacid sites are created by introducing chelating sulfates on the uncoordinated metal clusters, providing high proton donation capability. The obtained nanomaterials drastically reduce the energy consumption of CO
2
capture by 44.7% using only 0.1 wt.% nanocatalyst, which is a ∽10-fold improvement in efficiency compared to heterogeneous catalysts. This research represents a new avenue for the next generation of advanced nanomaterials in catalytic solvent regeneration.
Polymer brush surfaces that alter their physical properties in response to chemical stimuli have the capacity to be used as new surface‐based sensing materials. For such surfaces, detecting the ...polymer conformation is key to their sensing capabilities. Herein, we report on FRET‐integrated ultrathin (<70 nm) polymer brush surfaces that exhibit stimuli‐dependent FRET with changing brush conformation. Poly(N‐isopropylacrylamide) polymers were chosen due their exceptional sensitivity to liquid mixture compositions and their ability to be assembled into well‐defined polymer brushes. The brush transitions were used to optically sense changes in liquid mixture compositions with high spatial resolution (tens of micrometers), where the FRET coupling allowed for noninvasive observation of brush transitions around complex interfaces with real‐time sensing of the liquid environment. Our methods have the potential to be leveraged towards greater surface‐based sensing capabilities at intricate interfaces.
FRET chemistry was integrated within stimuli‐responsive polymer brush layers on planar substrates for spatial sensing of changing polymer conformations. Sensing was demonstrated for a variety of liquid mixture compositions, including high‐resolution observation of lateral differences in polymer conformation at immiscible liquid interfaces (see picture), thus offering great potential to be leveraged for new surface‐based sensing devices.
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Deep eutectic solvents (DESs) are a tailorable class of solvents that are rapidly gaining scientific and industrial interest. This is because they are distinct from conventional ...molecular solvents, inherently tuneable via careful selection of constituents, and possess many attractive properties for applications, including catalysis, chemical extraction, reaction media, novel lubricants, materials chemistry, and electrochemistry. DESs are a class of solvents composed solely of hydrogen bond donors and acceptors with a melting point lower than the individual components and are often fluidic at room temperature. A unique feature of DESs is that they possess distinct bulk liquid and interfacial nanostructure, which results from intra- and inter-molecular interactions, including coulomb forces, hydrogen bonding, van der Waals interactions, electrostatics, dispersion forces, and apolar-polar segregation. This nanostructure manifests as preferential spatial arrangements of the different species, and exists over several length scales, from molecular- to nano- and meso-scales. The physicochemical properties of DESs are dictated by structure–property relationships; however, there is a significant gap in our understanding of the underlying factors which govern their solvent properties. This is a major limitation of DES-based technologies, as nanostructure can significantly influence physical properties and thus potential applications. This perspective provides an overview of the current state of knowledge of DES nanostructure, both in the bulk liquid and at solid interfaces. We provide definitions which clearly distinguish DESs as a unique solvent class, rather than a subset of ILs. An appraisal of recent work provides hints towards trends in structure–property relationships, while also highlighting inconsistencies within the literature suggesting new research directions for the field. It is hoped that this review will provide insight into DES nanostructure, their potential applications, and development of a robust framework for systematic investigation moving forward.
Water is a unique solvent that is ubiquitous in biology and present in a variety of solutions, mixtures, and materials settings. It therefore forms the basis for all molecular dynamics simulations of ...biological phenomena, as well as for many chemical, industrial, and materials investigations. Over the years, many water models have been developed, and it remains a challenge to find a single water model that accurately reproduces all experimental properties of water simultaneously. Here, we report a comprehensive comparison of structural and dynamic properties of 30 commonly used 3-point, 4-point, 5-point, and polarizable water models simulated using consistent settings and analysis methods. For the properties of density, coordination number, surface tension, dielectric constant, self-diffusion coefficient, and solvation free energy of methane, models published within the past two decades consistently show better agreement with experimental values compared to models published earlier, albeit with some notable exceptions. However, no single model reproduced all experimental values exactly, highlighting the need to carefully choose a water model for a particular study, depending on the phenomena of interest. Finally, machine learning algorithms quantified the relationship between the water model force field parameters and the resulting bulk properties, providing insight into the parameter–property relationship and illustrating the challenges of developing a water model that can accurately reproduce all properties of water simultaneously.
Quantum-sized metallic clusters protected by biological ligands represent a new class of luminescent materials; yet the understanding of structural information and photoluminescence origin of these ...ultrasmall clusters remains a challenge. Herein we systematically study the surface ligand dynamics and ligand–metal core interactions of peptide-protected gold nanoclusters (AuNCs) with combined experimental characterizations and theoretical molecular simulations. We show that the peptide sequence plays an important role in determining the surface peptide structuring, interfacial water dynamics and ligand–Au core interaction, which can be tailored by controlling peptide acetylation, constituent amino acid electron donating/withdrawing capacity, aromaticity/hydrophobicity and by adjusting environmental pH. Specifically, emission enhancement is achieved through increasing the electron density of surface ligands in proximity to the Au core, discouraging photoinduced quenching, and by reducing the amount of surface-bound water molecules. These findings provide key design principles for understanding the surface dynamics of peptide-protected nanoparticles and maximizing the photoluminescence of metallic clusters through the exploitation of biologically relevant ligand properties.
Nitroreductase enzymes are of interest as antibiotic targets and as activators in enzyme prodrug therapy, but the precise substrate binding orientation and reaction mechanism are poorly understood. ...In order to design more effective antibiotics and improve enzyme prodrug therapy, an atomistic description of nitroaromatic substrate binding in the active Michaelis complex is highly desirable. Here, using an iterative molecular dynamics (MD) simulation protocol, the binding of p-nitrobenzoic acid (p-NBA) in oxidized and reduced
Enterobacter cloacae
nitroreductase (NR) was investigated. For the oxidized NR, the MD simulations distinguished between the two possible binding orientations of p-NBA in NR from X-ray crystal structure data. For the reduced NR, a distinct active binding orientation of p-NBA was found when the second active site of the NR homodimer was occupied by a NADH analogue. This model of the active Michaelis complex of p-NBA with NR provides a rationale for the reduction of p-NBA by NR via a hydride transfer reaction mechanism suggested by experimental results, and brings the proposed reaction mechanism from experiment and computational models into agreement.
NfsB has been studied extensively for its potential for cancer gene therapy by reducing the prodrug CB1954 to a cytotoxic derivative. We have previously made several mutants with enhanced activity ...for the prodrug and characterised their activity in vitro and in vivo. Here, we determine the X-ray structure of our most active triple and double mutants to date, T41Q/N71S/F124T and T41L/N71S. The two mutant proteins have lower redox potentials than wild-type NfsB, and the mutations have lowered activity with NADH so that, in contrast to the wild-type enzyme, the reduction of the enzyme by NADH, rather than the reaction with CB1954, has a slower maximum rate. The structure of the triple mutant shows the interaction between Q41 and T124, explaining the synergy between these two mutations. Based on these structures, we selected mutants with even higher activity. The most active one contains T41Q/N71S/F124T/M127V, in which the additional M127V mutation enlarges a small channel to the active site. Molecular dynamics simulations show that the mutations or reduction of the FMN cofactors of the protein has little effect on its dynamics and that the largest backbone fluctuations occur at residues that flank the active site, contributing towards its broad substrate range.
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