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Abstract Diamond as a material has many unique properties. Its high optical dispersion, extraordinarily high mechanical strength, and unparalleled thermal conductivity have long made it a material of interest for applications such as high‐temperature electronics and as wear‐resistance coatings. More recently, diamond has emerged as a material with a wide range of applications in chemistry and biology. The high intrinsic stability of diamond, coupled with the ability to modify diamond surfaces with a wide range of inorganic, organic, and biological species via highly stable covalent linkages, provides a wealth of opportunity to couple diamond's chemical properties with its extraordinary physical properties. The practical utility of diamond has been greatly expanded in recent years through dramatic advances in the ability to produce diamond in bulk, thin film, and nanoparticle form, with controlled doping and purity at modest cost. These advances, together with diamond's highly stable and tunable surface chemistry with versatility of physical structure enable a wide range of emerging applications of interest to chemists, including quantum science, biomedicine, energy storage, and catalysis. Yet, to fully exploit the unique properties of diamond, some formidable chemical challenges lie ahead. We begin by reviewing some of the features of diamond that are of particular importance to the chemistry community. We aim to highlight some of the important applications where diamond chemistry plays a key role, identify some of the key observations, and outline some of the future directions and opportunities for diamond in the chemical world. 

ABSTRACT Penicillin-binding proteins (PBPs) play critical roles in cell wall construction, cell shape maintenance, and bacterial replication. Bacteria maintain a diversity of PBPs, indicating that despite their apparent functional redundancy, there is differentiation across the PBP family. Apparently-redundant proteins can be important for enabling an organism to cope with environmental stressors. In this study, we evaluated the consequence of environmental pH on PBP enzymatic activity inBacillus subtilis. Our data show that a subset of PBPs inB. subtilischange activity levels during alkaline shock and that one PBP isoform is rapidly modified to generate a smaller protein (i.e., PBP1a to PBP1b). Our results indicate that a subset of the PBPs are favored for growth under alkaline conditions, while others are readily dispensable. Indeed, we found that this phenomenon could also be observed inStreptococcus pneumoniae, implying that it may be generalizable across additional bacterial species and further emphasizing the evolutionary benefit of maintaining many, seemingly-redundant periplasmic enzymes. IMPORTANCEMicrobes adapt to ever-changing environments and thrive over a vast range of conditions. While bacterial genomes are relatively small, significant portions encode for “redundant” functions. Apparent redundancy is especially pervasive in bacterial proteins that reside outside of the inner membrane. While conditions within the cytoplasm are carefully controlled, those of the periplasmic space are largely determined by the cell’s exterior environment. As a result, proteins within this environmentally exposed region must be capable of functioning under a vast array of conditions, and/or there must be several similar proteins that have evolved to function under a variety of conditions. This study examines the activity of a class of enzymes that is essential in cell wall construction to determine if individual proteins might be adapted for activity under particular growth conditions. Our results indicate that a subset of these proteins are preferred for growth under alkaline conditions, while others are readily dispensable. 

Abstract Seed-mediated synthesis strategies, in which small gold nanoparticle precursors are added to a growth solution to initiate heterogeneous nucleation, are among the most prevalent, simple, and productive methodologies for generating well-defined colloidal anisotropic nanostructures. However, the size, structure, and chemical properties of the seeds remain poorly understood, which partially explains the lack of mechanistic understanding of many particle growth reactions. Here, we identify the majority component in the seed solution as an atomically precise gold nanocluster, consisting of a 32-atom Au core with 8 halide ligands and 12 neutral ligands constituting a bound ion pair between a halide and the cationic surfactant: Au₃₂X₈[AQA⁺•X^-]₁₂(X = Cl, Br; AQA = alkyl quaternary ammonium). Ligand exchange is dynamic and versatile, occurring on the order of minutes and allowing for the formation of 48 distinct Au₃₂clusters with AQAX (alkyl quaternary ammonium halide) ligands. Anisotropic nanoparticle syntheses seeded with solutions enriched in Au₃₂X₈[AQA⁺•X^-]₁₂show narrower size distributions and fewer impurity particle shapes, indicating the importance of this cluster as a precursor to the growth of well-defined nanostructures. 

Nanoplastics, small plastic particles smaller than microplastics, have been suggested to have a wide-range of unique interactions when they encounter lipid membranes. Recent studies have demonstrated that the smaller size of nanoplastic particles may allow them to penetrate and dissolve in lipid membranes. Following this penetration, however, there is not yet a clear picture of how such particles impact the local lipid environment. A recent study by the present authors found that when lipid vesicles that included laurdan, a fluorescent dye molecule typically thought to report on the membrane phase, were exposed to polystyrene nanoparticles, they exhibited a concentration-dependent blue shift consistent with a fluid-to-gel phase transition. However, coarse-grained simulations suggested that no such transition was taking place; instead, the simulations observed that polymer chains from the polystyrene nanoparticles penetrated into the liposome membrane. In the present work, we use all-atom molecular dynamics simulations to demonstrate that the inclusion of polystyrene within a lipid membrane causes significant changes to the local hydration and structure of that membrane while maintaining the membrane phase. Specifically, through the explicit incorporation of laurdan within the present simulations, we demonstrate that the local hydration environment of the dye molecule changes significantly but continuously as membranes are exposed to polystyrene, thus suggesting a possible explanation for the previously reported experimental observation. The present results provide a picture of the complex heterogeneity generated within polymer-containing membranes. 

Understanding the cell membrane penetration process of biomedical nanosystems and its dependence on nanomaterial properties and surface functionalization is crucial for the rational design of safe and efficient cellular internalization strategies. Computer simulations are powerful tools to evaluate the thermodynamic aspects of the process and to elucidate its underlying molecular mechanisms. In this work, the interaction between uncoated or polymer-coated graphene oxide (GO) dots and lipid bilayer models is investigated by coarse-grained (CG) molecular dynamics (MD) simulations. We first validate the coarse-grained model against all-atom MD simulations (AAMD). Then, we perform CGMD simulations and free energy calculations to assess the effect of the polymeric coating and of its features (grafting density, polymer end-group charge and polymer hydrophilic/hydrophobic character) on the interaction between GO dots of realistic size and lipid membranes. We find that the membrane penetration of GO dots is spontaneous when coated with a low-density polyethylene glycol (PEG) layer, while a high-density PEG coating prevents the penetration, and a mixed PEG/polyethylene (PE) coating excessively stabilizes the nanosystem in the inner membrane region. These findings will help to fine-tune how GO dots interact with cellular membranes. 

While biopolymers have the potential to enhance agrochemical delivery and mitigate environmental impacts such as runoff, previous plant studies have often been limited to examining single biopolymers in isolation. This approach has hindered effective comparisons of plant outcomes due to variations in plant type, growth duration, and soil characteristics. The current study addresses this gap by incorporating six separate milled biopolymers: pectin, starch, chitosan, polycaprolactone (PCL), polylactic acid (PLA), or polyhydroxybutyrate (PHB) into soil and directly comparing their impacts on tomato (Solanum lycopersicum) plants cultivated under identical environmental parameters. Plant outcomes were also studied when biopolymers were modified via the inclusion of two phosphorus (P) salts, forming two types of Polymer-P-containing salt composites with amorphous CaPO4 (CaP) and CaHPO4 (DCP). Our results revealed that chitosan-based treatments significantly improved tomato root and shoot biomass, with increases of 200–300% compared to the control plants. Chitosan-CaP and Chitosan-DCP also enhanced P uptake, though the effect was significantly more pronounced in the former, suggesting a synergy between chitosan and CaP. Neither Chitosan-P-containing salt treatment, however, mitigated P leaching from soil when compared to CaP or DCP applied in isolation. The two most hydrophilic biopolymers, pectin and starch, as well as their P-salt-containing counterparts, showed the most substantial reductions in biomass (∼80%) with respect to control plants, while similarly lowering P uptake and P retention in soil compared to CaP- and DCP-only plants. PCL- and PHB-based treatments also adversely influenced biomass and plant P, though these effects were not as drastic as those observed with pectin and starch. PLA-based soil amendments had no effect on any plant performance metric, though PLA-CaP, specifically, was the only treatment to appreciably mitigate P leaching (−63%). Based on these findings, subsequent tomato growth experiments were conducted over a longer 8-week period with CaP, DCP, Chitosan, Chitosan-CaP, and Chitosan-DCP. While all chitosan-treated plants showed similar enhancements in biomass, plants treated with Chitosan-CaP and Chitosan-DCP were the only ones to fruit, demonstrating the benefit of using chitosan in conjunction with a P source as compared to either treatment in isolation. These findings contribute to an expanding body of evidence that biopolymer carriers can offer a more sustainable approach to improving the precision of nutrient delivery, while also highlighting the pivotal role of biopolymer and nutrient type in the development of these carriers. 

Characterization and prediction of the interactions between engineered nanoparticles (ENPs), proteins, and biological membranes is critical for advancing applications to nanomedicine and nanomanufacturing while mitigating nanotoxicological risks. In this work, we employ a coarse-grained dissipative particle dynamics (DPD) simulation to investigate the interactions among cytochrome c (CytC), lipid bilayers, and citrate-coated gold nanoparticles (AuNPs). We updated the DPD potential to accurately represent binding potentials between molecules, and validated the model relative to an all-atom representation. The DPD simulations successfully replicate experimental observations: CytC facilitates the binding of citrate-coated AuNPs to lipid bilayers composed of 90% dioleoylphosphatidylcholine (DOPC) mixed with 10% stearoylphosphatidylinositol (SAPI) or 10% tetraoleoyl cardiolipin (TOCL) but not to pure 100% DOPC bilayers. In addition, the simulations reveal nuanced differences in binding preferences between CytC, the lipid bilayers, and the ENP, at a scale that is not presently directly observable in experiments. Specifically, we found that the surface coating of the nanoparticles─viz variations in the CytC surface density─affects the protein-mediated binding with the bilayers. Such a molecular-sensitive result underscores the utility of DPD simulations in simulating complex biological systems. 

Reactive oxygen species (ROS) are common cellular oxidants that when overproduced by cellular stressors cause harm to cells. Detection of ROS is of utmost importance to understanding a wide variety of cellular function and toxicity mechanisms. Conventional ROS fluorescence assays involve using a single dye to visualize the ROS quantity. Herein, we describe ROS-sensitive, fluorescent-dye-incorporated carbon dots with dual fluorescence capabilities and good biocompatibility. Carbon dots (CDs) made of citric acid and urea were synthesized with incorporated cyanine-3-amine (Cy3), a bright red fluorescent dye, to create Cy3-CDs. To get Cy3 into the ROS-sensitive form, this work demonstrated that Cy3 alone and Cy3 within carbon dots can be electrochemically reduced to their colorless ROS-sensitive form. Cy3, CDs, and Cy3-CDs are all responsive to additions of superoxide, leading to an increase in the fluorescence. Overall, this work examines how O2•– and additional oxidizers interact with CDs, Cy3, and Cy3-CDs, and molecular-level hypotheses are explored that will inform the design of future carbon dot-based ROS sensors. 

Controlled-release materials are desirable for many delivery applications and have been used to improve the efficiency of fertilizers and pesticides in crop management. Due to their potential to reduce application of toxic chemicals while prolonging exposure to active agents, controlled-release nanomaterials are currently being investigated for increasing agricultural production and preventing overfertilization. Hydrogels are underexplored as controlled-release nanomaterials and can deliver many types of cargo, from metal ions to small molecules. Alginate-based hydrogels are biocompatible and their internal carboxylic acids coordinate agriculturally valuable micronutrients like Cu2+, Zn2+, and Ca2+. Hydrogels comprising ionic and nonionic polymers can coordinate agriculturally valuable micronutrients, and the combination of ionic and nonionic polymers results in hydrogels with tunable release profiles. Alginate, for example, contains carboxylates that ionically cross-link with divalent cations like Cu2+, Zn2+, and Ca2+, while polar moieties on chitin enable nonionic coordination. To our knowledge, soft-material copper-loaded nanoparticles have not yet been applied as controlled-release materials for foliar delivery. In this work, we present the synthesis and micronutrient release characteristics of hydrogel nanoparticles containing Cu2+, which is coordinated by ionic and nonionic polymers. Hydrogel nanoparticles (HNPs) were prepared by liquid–liquid emulsion techniques and cross-linked with Cu2+ to form double-network hydrogels made from alginate and non-cross-linking chitin. Nanoparticles (100–300 nm in diameter) were characterized by cryogenic electron microscopy, nanoparticle tracking analysis, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The copper release profiles of HNPs with different polymer compositions were compared. HNPs containing both chitin and alginate released 8–20 times more copper than HNPs with alginate alone, suggesting that the presence of non-cross-linking polymers improves copper release. Thus, HNP delivery characteristics can be tuned by manipulating intraparticle bond dynamics in the hydrogel polymer matrix. 

Global food security is a pressing issue in our society. Maintaining food security in coming years will require improving crop yield, as well as increased resiliency to abiotic and biotic stress. Nanoscale materials have increasingly been proposed as a tool which could be used to meet these challenges. However, much research is needed to optimize nanoparticle design and crop application for this to become a reality. In this study, we investigated the impact of polymer-functionalized carbon dots on tomatoes (Solanum lycopersicum L.). Tomato seeds were vacuum infiltrated with carbon dots and then grown for 3 weeks before collection of phenotypic and transcriptomic data. No changes to fresh biomass or chlorophyll content were observed, indicating that these particles can be applied without overt harm to the plant at early growth stages. In addition, changes in gene expression suggest that polymer-functionalized carbon dots can initiate the expression of biochemical pathways associated with a pathogen resistance response in tomato plants. Specifically, genes involved in ethylene signaling, ethylene production, and camalexin synthesis were upregulated. These findings suggest that seed priming with carbon dots may improve plant tolerance to biotic stress by modulating ethylene signaling pathways. Carbon dots could also be loaded with nutrients or other agrochemicals to create a multifunctional platform. Future work should focus on understanding the mechanisms by which nanoparticles can modulate ethylene signaling, enabling use of this knowledge to develop sustainable and effective nanoparticles for agricultural applications.