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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. 

Large scale commercial cultivation of microalgae year-round is limited by seasonal stress conditions. The rapid growth and high CO2 capture of the marine microalga Picochlorum celeri is largely inhibited under winter stress conditions of low temperature and high light. Herein, we demonstrated a nanotechnology approach to enhance the biomass productivity and CO2 capture of P. celeri under abiotic stress by interfacing with antioxidant cerium oxide nanozymes (nanoceria). Antioxidant nanoceria catalytically scavenged reactive oxygen species (ROS) generated under stress conditions, reducing damage to the microalgae photosynthetic machinery in chloroplasts. Negatively charged poly-acrylic acid-coated nanoceria (PNC, 10 μM) were biocompatible in microalgae cells and colocalized with chloroplasts. In contrast, positively charged aminated nanoceria (ANC) resulted in microalgae aggregation (>50 μM) and were toxic at all concentrations tested (≥10 μM). PNC reduction of ROS levels in microalgae (78%) and superoxide levels (26%), enhanced microalgae growth (65%), photosynthetic performance (130%), and CO2 uptake rate (380%) under low-temperature stress (15 °C) and high light (500 μmol/m2/s PAR) stress relative to controls without nanoceria. Nanoceria augmentation of microalgae provides a rapid and facile technology to increase algae CO2 capture and biomass under stress conditions. 

Nanoparticle surface chemistry characteristics are key factors that determine their behavior upon interaction with different organisms. In particular, electrostatic interactions between nanoparticles and plant-type organisms have been well-characterized; however, the impact of the degree of hydrophobicity remains largely unexplored. Here, ultraporous mesostructured silica nanoparticles (UMNs) were functionalized with different ratios of chlorotrimethylsilane (TMS) to 2-[methoxy(polyethyleneoxy)9–12propyl]trimethoxysilane (PEG) to systematically tune their hydrophobicity, and were subsequently used to interrogate how the degree of hydrophobicity affects nanoparticle interactions at the biointerface of the green alga, Raphidocelis subcapitata. Using high-content imaging and phenotypic profiling, the levels of UMN internalization, subcellular trafficking, and their associated phenotypic and physiological impacts were quantified. Increasing the PEG content on the surface of the UMNs, which decreased particle hydrophobicity, was found to significantly enhance levels of internalization, but did not alter translocation within the cells. Colocalization analyses indicated a strong association between UMNs and F-actin filaments after 1–24 hours of exposure, which was independent of PEG content and degree of UMN hydrophobicity, as there was no significant difference between particle types. However, after 48 hours, cells appeared to have incorporated a portion of UMNs into their cell walls while depositing the remainder into vacuolated spaces. Lastly, UMNs had a significant impact on phenotype complexity, with specific metrics including enhanced chlorophyll production and shifts in cell cycle progression; however, no growth inhibition was observed after 72 hours. Overall, using this approach, it was found that tuning the degree of UMN hydrophobicity had a significant impact on the levels of internalization. However, once inside the cells, the degree of hydrophobicity did not have a significant impact on translocation, phenotype, or physiological response as each particle type elicited similar cellular responses. 

Food insecurity is a prominent global issue. With a predicted global population of 9 billion by 2050, food production must double at a minimum to accommodate these growing numbers. One approach to combat food insecurity is targeting plant pathogens that affect crop quality and yield, resulting in an overall increase in edible food production. Plant pathogen management has previously utilized the RNA interference (RNAi) mechanism for remediation; however, its widespread use has technical limitations. In this study, silica nanoparticles (SiO2 NPs) were utilized as nanocarriers of therapeutic double-stranded ribonucleic acid (dsRNA) to enhance dsRNA delivery into plant cells, thereby activating the RNAi system and suppressing the occurrence of potato virus Y (PVY). This highly mutable pathogen causes several adverse effects in potato and other crop plants. Fast-dissolving silica (FDS) nanoparticles, mesoporous silica nanoparticles (MSNs), and ultraporous mesostructured silica nanoparticles (UMNs) with negative and positive surface charges were synthesized. After thorough characterization, nine distinct SiO2 NP formulations were loaded with dsRNA, with UMNs showing the best loading capacity. Due to the negatively charged nature of dsRNA, positively charged UMNs were favored and employed in further application experiments. Gel electrophoresis indicated that dsRNA loaded into/onto these UMNs was released over several days. Fifteen days after inoculation, greenhouse experiments with tobacco plants demonstrated that dsRNA-loaded UMNs effectively suppressed PVY. In a field study, dsRNA loaded into/onto UMNs showed a 0% disease incidence, an improvement compared to dsRNA or nanoparticle application alone. These findings reveal that UMNs are an efficient nanocarrier for delivering dsRNA against PVY, thereby increasing crop health and yield. A techno-economic analysis was performed to evaluate the economic viability of this nanomaterial for industrial commercialization. 

n response to the worldwide presence of per- and polyfluoroalkyl substances (PFAS) in the environment, there has been a great focus on developing effective PFAS removal technology to address this class of contaminants that pose a threat to human and environmental health. Sorbent materials have been a significant focus in PFAS remediation technology; however, the molecular-level interactions between PFAS and sorbent materials are often overlooked or not explored, despite the important role they play in sorbent performance. The objective of this perspective is to showcase how different analytical techniques can be used to provide critical insight into the fundamental interactions between PFAS molecules and sorbent materials. Herein, we discuss the power of various experimental and computational techniques to unveil the fundamental chemistry driving PFAS-sorbent interactions, revealing critical information for the development of robust remediation materials. 

Nanomaterials are being increasingly studied for their use in agriculture to promote healthy crop growth and mitigate the damaging effects of plant diseases. Copper is among the elements delivered and managed with nanoenabled-agriculture practices, but it is challenging to balance copper levels because some doses mitigate disease, but in excess, it can be harmful and interrupt photosynthetic function. Carbon dots (CDs) are an emerging, sustainable class of fluorescent nanomaterials with affinity for copper ions that possess good biocompatibility and low toxicity, making them an ideal candidate for use in crop applications. Here, a range of CDs were synthesized from citric acid and urea with varied affinity for copper ions. We investigated how chelated copper affects CD fluorescence and structure, and we propose a mechanism for the chelation of Cu2+ by CDs. Additionally, the effects of the Cu–CD complex on both healthy and disease-bearing tomato plants were evaluated. The data show that the complex had no toxic effects on the plant and can increase seedling biomass by 44–61% when applied through a vacuum seed infiltration method. The desorption of copper from the Cu–CD complex exhibited a slow-release profile, indicating that CDs could be an effective tool for mitigating excess copper in plants. 

Per- and polyfluoroalkyl substances (PFAS) are environmental contaminants that are raising growing global concerns due to their environmental persistence, widespread distribution, bioaccumulation ability, and potential health risks. There is a critical need to develop efficient and environmentally safe remediation methods to protect the safety of society and the ecosystem. Therefore, this thesis focuses on advancing PFAS remediation through the development, understanding, and application of silica-based nanomaterials, particularly ultraporous mesostructured silica nanoparticles (UMNs), for PFAS remediation. 

Developing new technologies for removal of per- and polyfluoroalkyl substances (PFAS) from water is critical for public and environmental safety. In conjunction, suitable analytical techniques are required for understanding interactions between novel sorbent materials and PFAS to facilitate efforts on designing improved materials. In this work, six nanoscale carbon dots (CDs) are synthesized for fundamental PFAS sorption studies, and 19F NMR is introduced as a primary analytical technique to rank and understand the affinity of the synthesized CDs toward PFAS. The CDs are synthesized from various-amine rich precursors (polyethylenimine or chitosan) to yield cationic CDs and promote electrostatic interactions with anionic PFAS. The affinity of CDs toward perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), and a mixture of 24 PFAS was assessed. Three main approaches were used to rank CD affinity for PFAS: Kd determination using 1D NMR and two CPMG-based methods. Based on Kd values, the PEI CDs exhibited higher affinity for PFOA than any of the chitosan-based CDs or β-cyclodextrin, while affinity for PFOS was comparable across all sorbent materials. CMPG-based experiments suggested that PEI CDs have superior affinity for PFOA and operate in a slower exchange regime with PFOA than the chitosan-based CDs. In the PFAS mixture, the PEI-CDs and top-performing chitosan-based CDs interacted strongly with PFAS of varying chain lengths and identity. These results indicate that CDs should continue to be explored for their high PFAS affinity and solidifies the power of 19F NMR techniques to provide critical molecular-level information about PFAS-sorbent interactions in suspension. 

Per- and polyfluoroalkyl substances (PFAS) are a large class of fluorinated chemicals used widely in industrial and consumer products due to their innate thermal and chemical stability. Concerns about PFAS have been raised globally due to their environmental persistence, potential to bioaccumulate, and negative human health implications. As a result, developing adequate technologies for mitigating PFAS contamination is critical for public and environmental safety. Thus, this thesis focuses on developing tools to help the field of PFAS remediation across two main overarching themes. First, developing analytical methods to probe complex PFAS interactions with advanced PFAS remediation materials. Second, exploring carbon dots (CDs) as a potential promising material to facilitate PFAS remediation across several systems.