Nanoparticle-assisted tubulin assembly is environment dependent.

Nanomaterials acquire a biomolecular corona upon introduction to biological media, leading to biological transformations such as changes in protein function, unmasking of epitopes, and protein fibrilization. Ex vivo studies to investigate the effect of nanoparticles on protein-protein interactions are typically performed in buffer and are rarely measured quantitatively in live cells. Here, we measure the differential effect of silica nanoparticles on protein association in vitro vs. in mammalian cells. BtubA and BtubB are a pair of bacterial tubulin proteins identified in Prosthecobacter strains that self-assemble like eukaryotic tubulin, first into dimers and then into microtubules in vitro or in vivo. Förster resonance energy transfer labeling of each of the Btub monomers with a donor (mEGFP) and acceptor (mRuby3) fluorescent protein provides a quantitative tool to measure their binding interactions in the presence of unfunctionalized silica nanoparticles in buffer and in cells using fluorescence spectroscopy and microscopy. We show that silica nanoparticles enhance BtubAB dimerization in buffer due to protein corona formation. However, these nanoparticles have little effect on bacterial tubulin self-assembly in the complex mammalian cellular environment. Thus, the effect of nanomaterials on protein-protein interactions may not be readily translated from the test tube to the cell in the absence of particle surface functionalization that can enable targeted protein-nanoparticle interactions to withstand competitive binding in the nanoparticle corona from other biomolecules.

The Landscape of Gold Nanocrystal Surface Chemistry.

ConspectusGold nanoparticles (AuNPs) exhibit unique size- and shape-dependent properties not obtainable at the macroscale. Gold nanorods (AuNRs), with their morphology-dependent optical properties, ability to convert light to heat, and high surface-to-volume ratios, are of great interest for biosensing, medicine, and catalysis. While the gold core provides many fascinating properties, this Account focuses on AuNP soft surface coatings, which govern the interactions of nanoparticles with the local environments. Postmodification of AuNP surface chemistry can greatly alter NP colloidal stability, nano-bio interactions, and functionality. Polyelectrolyte coatings provide controllable surface-coating thickness and charge, which impact the composition of the acquired corona in biological settings. Covalent modification, in which covalently bound ligands replace the original capping layer, is often performed with thiols and disulfides due to their ability to replace native coatings. N-heterocyclic carbenes and looped peptides expand the possible functionalities of the ligand layer.The characterization of surface ligands bound to AuNPs, in terms of ligand density and dynamics, remains a challenge. Nuclear magnetic resonance (NMR) spectroscopy is a powerful tool for understanding molecular structures and dynamics. Our recent NMR work on AuNPs demonstrated that NMR data were obtainable for ligands on NPs with diameters up to 25 nm for the first time. This was facilitated by the strong proton NMR signals of the trimethylammonium headgroup, which are present in a distinct regime from other ligand protons' signals. Ligand density analyses showed that the smallest AuNPs (below 4 nm) had the largest ligand densities, yet spin-spin T2 measurements revealed that these smallest NPs also had the most mobile ligand headgroups. Molecular dynamics simulations were able to reconcile these seemingly contradictory results.While NMR spectroscopy provides ligand information averaged over many NPs, the ligand distribution on individual particles' surfaces must also be probed to fully understand the surface coating. Taking advantage of improvements in electron energy loss spectroscopy (EELS) detectors employed with scanning transmission electron microscopy (STEM), a single-layer graphene substrate was used to calibrate the carbon K-edge EELS signal, allowing quantitative imaging of the carbon atom densities on AuNRs with sub-nanometer spatial resolution. In collaboration with others, we revealed that the mean value for surfactant-bilayer-coated AuNRs had 10-30% reduced ligand density at the ends of the rods compared to the sides, confirming prior indirect evidence for spatially distinct ligand densities.Recent work has found that surface ligands on nanoparticles can, somewhat surprisingly, enhance the selectivity and efficiency of the electrocatalytic reduction of CO2 by controlling access to the active site, tuning its electronic and chemical environment, or denying entry to impurities that poison the nanoparticle surface to facilitate reduction. Looking to the future, while NMR and EELS are powerful and complementary techniques for investigating surface coatings on AuNPs, the frontier of this field includes the development of methods to probe the surface ligands of individual NPs in a high-throughput manner, to monitor nano-bio interactions within complex matrices, and to study structure-property relationships of AuNPs in biological systems.

In-Cell Association of a Bioorthogonal Tubulin.

Studies of proteins from one organism in another organism's cells have shown that such exogenous proteins stick more, pointing toward coevolution of the cytoplasm and protein surface to minimize stickiness. Here we flip this question around by asking whether exogenous proteins can assemble efficiently into their target complexes in a non-native cytoplasm. We use as our model system the assembly of BtubA and BtubB from Prosthecobacter hosted in human U-2 OS cells. BtubA and B evolved from eukaryotic tubulins after horizontal gene transfer, but they have low surface sequence identity with the homologous human tubulins and do not respond to tubulin drugs such as nocodazole. In U-2 OS cells, BtubA and B assemble efficiently into dimers compared to in vitro, and the wild-type BtubA and B proteins subsequently are able to form microtubules as well. We find that generic crowding effects (Ficoll 70 in vitro) contribute significantly to efficient dimer assembly when compared to sticking interactions (U-2 OS cell lysate in vitro), consistent with the notion that a generic mechanism such as crowding can be effective at driving assembly of exogenous proteins, even when protein-cytoplasm quinary structure and sticking have been modified in a non-native cytoplasm. A simple Monte Carlo model of in vitro and in-cell interactions, treating BtubA and B as sticky dipoles in a matrix of sticky or nonsticky crowders, rationalizes all the experimental trends with two adjustable parameters and reveals nucleation as the likely mechanism for the time-scale separation between dimer- and tubule formation in-cell and in vitro.

Healthcare professionals' experiences and views of providing continence support and advice to people living at home with dementia: "That's a carer's job".

BACKGROUND: People living with dementia at home and their family carers often feel unsupported by healthcare professionals in managing continence problems. In turn, primary and community-based healthcare professionals have reported lacking specific knowledge on dementia-continence. This study aimed to understand more about healthcare professionals' experiences and views of supporting people living with dementia experiencing continence problems, as part of developing acceptable resources. Having a nuanced understanding of unmet need would facilitate the design of engaging resources that enable healthcare professionals to provide more effective continence support to people living with dementia at home. METHODS: Semi-structured interviews were conducted with a range of healthcare professionals (n = 31) working in primary and community care in the South of England in 2023. Transcribed interviews were uploaded to NVivo 12, then analysed inductively and deductively using a thematic framework. RESULTS: Continence-related conversations were avoided by many healthcare professionals due to lack of dementia-continence specific knowledge. Many considered that continence problems of people living with dementia were largely outside their remit once a physical cause had been ruled out. This contributed to a lack of priority and proactivity in raising the subject of continence in their consultations. Challenges to providing support included limited consultation time and lack of access to specialist services with availability to support individuals. CONCLUSION: There is substantial scope to support primary and community-based healthcare professionals in their provision of continence-related support and advice to people living at home with dementia. This includes addressing knowledge deficits, enhancing confidence and instilling a sense of accomplishment.

Child Sexual Abuse in the United States: A Commentary on Current Policy Approaches to Prevention and Aspirations for the Future.

Child sexual abuse (CSA) is a significant threat to the health and well-being of children in the United States (US). Public policies are a key public health strategy for the primary prevention of violence, including CSA. In 2021, the Enough Abuse Campaign and Prevent Child Abuse America published a comprehensive report entitled A Call to Action for Policymakers and Advocates: Child Sexual Abuse Prevention Legislation in the States to encourage state leaders to create a comprehensive strategy to prevent CSA in the US. Findings from the report show that the nation has made some effort to address CSA, but more focus needs to be given to primary prevention strategies that stop it from occurring in the first place. The report also illustrates the variability of CSA prevention policies across the US and highlights critical gaps in current approaches that must be addressed. In the spirit of the special issue, the authors reflect on key policy issues in the field, including the lack of a federal policy framework for CSA prevention, dedicated funding for the prevention of CSA, and research on the effectiveness of policies intended to prevent CSA. Suggestions for future directions in relation to policy development provided in this commentary will be useful to a variety of stakeholders interested in the topic of CSA prevention policy.

Adsorption and Molecular Display of a Redox-Active Protein on Gold Nanoparticle Surfaces.

Engineered gold nanoparticles (AuNPs) have great potential in many applications due to their tunable optical properties, facile synthesis, and surface functionalization via thiol chemistry. When exposed to a biological environment, NPs are coated with a protein corona that can alter the NPs' biological identity but can also affect the proteins' structures and functions. Protein disulfide isomerase (PDI) is an abundant protein responsible for the disulfide formation and isomerization that contribute to overall cell redox homeostasis and signaling. Given that AuNPs are widely employed in nanomedicine and PDI plays a functional role in various diseases, the interactions between oxidized (oPDI) and reduced (rPDI) with 50 nm citrate-coated AuNPs (AuNPs) are examined in this study using various techniques. Upon incubation, PDI adsorbs to the AuNP surface, which leads to a reduction in its enzymatic activity despite limited changes in secondary structures. Partial enzymatic digestion followed by mass spectrometry analysis shows that orientation of PDI on the NP surface is dependent on both its oxidation state and the PDI:AuNP incubation ratios.

Anionic nanoparticle-induced perturbation to phospholipid membranes affects ion channel function.

Understanding the mechanisms of nanoparticle interaction with cell membranes is essential for designing materials for applications such as bioimaging and drug delivery, as well as for assessing engineered nanomaterial safety. Much attention has focused on nanoparticles that bind strongly to biological membranes or induce membrane damage, leading to adverse impacts on cells. More subtle effects on membrane function mediated via changes in biophysical properties of the phospholipid bilayer have received little study. Here, we combine electrophysiology measurements, infrared spectroscopy, and molecular dynamics simulations to obtain insight into a mode of nanoparticle-mediated modulation of membrane protein function that was previously only hinted at in prior work. Electrophysiology measurements on gramicidin A (gA) ion channels embedded in planar suspended lipid bilayers demonstrate that anionic gold nanoparticles (AuNPs) reduce channel activity and extend channel lifetimes without disrupting membrane integrity, in a manner consistent with changes in membrane mechanical properties. Vibrational spectroscopy indicates that AuNP interaction with the bilayer does not perturb the conformation of membrane-embedded gA. Molecular dynamics simulations reinforce the experimental findings, showing that anionic AuNPs do not directly interact with embedded gA channels but perturb the local properties of lipid bilayers. Our results are most consistent with a mechanism in which anionic AuNPs disrupt ion channel function in an indirect manner by altering the mechanical properties of the surrounding bilayer. Alteration of membrane mechanical properties represents a potentially important mechanism by which nanoparticles induce biological effects, as the function of many embedded membrane proteins depends on phospholipid bilayer biophysical properties.

Regulating and Directionally Controlling Electron Emission from Gold Nanorods with Silica Coatings.

Dielectric coatings offer a versatile means of manipulating hot carrier emission from nanoplasmonic systems for emerging nanocatalysis and photocathode applications, with uniform coatings acting as regulators and nonuniform coatings providing directional photocurrent control. However, the mechanisms for electron emission through dense and mesoporous silica (SiO2) coatings require further examination. Here, we present a systematic investigation of photoemission from single gold nanorods as a function of dense versus mesoporous silica coating thicknesses. Studies with dense coatings on gold nanostructures clarify the short (∼1 nm) attenuation length responsible for severely reduced transmission through the silica conduction band. By contrast, mesoporous silica is much more transmissive, and a simple geometric model quantitatively recapitulates the electron escape probability through nanoscopic porous channels. Finally, photoelectron velocity map imaging (VMI) studies of nanorods with coating defects verify that photoemission occurs preferentially through the thinner regions, illustrating new opportunities for designing photocurrent distributions on the nanoscale.

Opportunities for Electrocatalytic CO2 Reduction Enabled by Surface Ligands.

To achieve high selectivity in enzyme catalysis, nature carefully controls both the catalyst active site and the pocket or environment that mediates access and the geometry of a reactant. Despite the many advantages of heterogeneous catalysis, active sites on a surface are rarely defined with atomic precision, making it difficult to control reaction selectivity with the molecular precision of homogeneous systems. In colloidal nanoparticle synthesis, structural control is accomplished using a surface ligand or capping layer that stabilizes a specific particle morphology and prevents nanoparticle aggregation. Usually, these surface ligands are considered detrimental for catalysis because they occupy otherwise active surface sites. However, a number of examples have shown that surface ligands can play a beneficial role in defining the catalytic environment and enhancing performance by a variety of mechanisms. This perspective summarizes recent advances and opportunities using surface ligands to enhance the performance of nanocatalysts for electrochemical CO2 reduction. Several mechanisms are discussed, including selective permeability, modulating interfacial solvation structure and electric fields, chemical activation, and templating active site selection. These examples inform strategies and point to emerging opportunities to design nanocatalysts toward molecular level control of electrochemical CO2 conversion.

Isolation Methods Influence the Protein Corona Composition on Gold-Coated Iron Oxide Nanoparticles.

Upon exposure to a biological environment, nanoparticles (NPs) acquire biomolecular coatings, the most studied of which is the protein corona. This protein corona gives NPs a new biological identity that will determine various biological responses including cellular uptake, biodistribution, and toxicity. The standard method to isolate NPs from a biological matrix in order to study their coronas is centrifugation, but more gentle means of retrieval may enable deeper understanding of both irreversibly bound hard coronas and more loosely bound soft coronas. In this study, magnetic gold-coated iron oxide NPs were incubated with rainbow trout gill cell total protein extracts and mass spectrometric proteomic analysis was conducted to determine the composition of the protein coronas isolated by either centrifugation or magnetic retrieval. The number of washes were varied to strip away the soft coronas and isolate the hard corona. Hundreds of proteins were adsorbed to the NPs. Some proteins were common to all isolation methods and many others were particular to the isolation method. Some qualitative trends in protein character were discerned from quantitative proteomic analyses, but more importantly, a new kind of protein corona was identified, mixed corona, in which the labile or inert nature of the protein-NP interaction is dependent upon sample history.

A qualitative study and preliminary model of living with dementia and incontinence at home: beyond containment.

BACKGROUND: most people living with dementia (PLWD) will develop incontinence problems with associated harmful consequences. Well-contained incontinence is often the main treatment goal. It would therefore be expected that poorly contained incontinence would have a negative impact. AIM: to investigate differences in how well-contained or poorly contained incontinence impacts on the experience of living with incontinence for PLWD at home and their carers. DESIGN: secondary analysis of a qualitative study. METHODS: semi-structured interviews were undertaken with PLWD, carers and healthcare professionals (continence or dementia nurses). PLWD and carers were recruited via www.joindementiaresearch.nihr.ac.uk and via dementia/carer groups. Nurses were recruited via their employers. Interviews were recorded and transcribed verbatim. Framework analysis was used. RESULTS: forty-five people (twenty-six carers, two PLWD, nine continence nurses and eight dementia nurses) participated. Despite poorly contained incontinence, some PLWD/carer dyads appeared relatively unaffected by incontinence. Conversely, one or both members of some dyads who achieved good containment found incontinence care highly challenging. Four themes were identified, together forming a preliminary model of incontinence containment and impact, as follows. CONCLUSION: reliable containment is an important goal for PLWD living at home and their carers, but it is not the only goal. Other factors, such as behaviours that challenge or carer coping strategies, can mean that even well-contained incontinence can have a negative impact. This paper proposes a preliminary model for evaluation.

Surface-Enhanced Raman Spectroscopy-Scanning Electrochemical Microscopy: Observation of Real-Time Surface pH Perturbations.

Understanding and controlling chemical dynamics at electrode interfaces is key to electrochemical applications in sensing, electrocatalysis, and energy storage. Here, we introduce colocalized surface-enhanced Raman scattering-scanning electrochemical microscopy (SERS-SECM) as a multimodal tool able to simultaneously probe and affect electrochemical interfaces in real time. As a model system to demonstrate SERS-SECM, we used a self-assembled monolayer of 4-mercaptopyridine (4MPy), a pH sensitive Raman indicator, anchored to silver nanoparticles as a substrate. We modulated the local pH at the surface with chronoamperometry, inducing the hydrogen evolution reaction (HER) at the SECM tip and observed subsequent Raman peak height changes in the 4MPy. We then performed cyclic voltammetry of HER at the SECM tip while measuring SERS spectra every 200 ms to highlight the technique's real-time capabilities. Our results show the capability to sensitively interrogate and trigger chemical/electrochemical dynamic surface phenomena. We hope SERS-SECM will provide insight on the link between heterogeneous and homogeneous reactivity at electrochemical interfaces.

How Do Proteins Associate with Nanoscale Metal-Organic Framework Surfaces?

It is well known that colloidal nanomaterials, upon exposure to a complex biological medium, acquire biomolecules on their surface to form coronas. Porous nanomaterials present an opportunity to sequester biomolecules and/or control their orientation at the surface. In this report, a metal-organic framework (MOF) shell around gold nanorods was compared to MOF nanocrystals as potential protein sponges to adsorb several common proteins (lysozyme, beta-lactoglobulin-A, and bovine serum albumin) and potentially control their orientation at the surface. Even after correction for surface area, MOF shell/gold nanorod materials adsorbed more protein than the analogous nanoMOFs. For the set of proteins and nanomaterials in this study, all protein-surface interactions were exothermic, as judged by isothermal titration calorimetry. Protein display at the surfaces was determined from limited proteolysis experiments, and it was found that protein orientation was dependent both on the nature of the nanoparticle surface and on the nature of the protein, with lysozyme and beta-lactoglobulin-A showing distinct molecular positioning.

Problems faced by people living at home with dementia and incontinence: causes, consequences and potential solutions.

BACKGROUND: many people living at home with dementia (PLWD) also have poorly managed toilet-use or incontinence problems with damaging consequences for both people with dementia, unpaid carers and healthcare professionals (HCPs). Currently, there are no theoretically or empirically based interventions to help. The underlying causes and subsequent consequences of these problems need to be fully understood in order to support the development of interventions that have the potential to decrease the impact of these problems on people's lives. AIM: to establish the range of causes, consequences and potential solutions of toilet-use and incontinence problems for PLWD and their carers. METHOD: a qualitative design was used. Semi-structured interviews were undertaken with PLWD, carers and HCPs (continence or dementia nurses). PLWD and carers were recruited via www.joindementiaresearch.nihr.ac.uk and via dementia/carer groups. Nurses were recruited via their employers. Interviews were digitally recorded and transcribed verbatim. Framework analysis was used to interpret the data to address the goal of the research. RESULTS: in total, 45 people (26 unpaid carers, 2 people with dementia, 9 continence and 8 dementia HCPs) took part. The causes of toilet-use and incontinence problems were reported to be multi-faceted and complex including those related to dementia (e.g. lack of insight into toileting needs or how to use the toilet), those which are physical (e.g. existing bladder or bowel issues or poor mobility), psychosocial (e.g. inability to ask for help for incontinence) or societal (e.g. fear of stigma), or related to care systems (e.g. lack of expert knowledge) or products (e.g. poor fit or confusing for users). Consequences included harms to physical and mental health, social isolation, increased carer workload and care system resource implications. CONCLUSION: this study provides the first detailed characterisation of the causes and consequences of and potential solutions for incontinence problems for PLWD at home and their carers. Multifaceted and complex problems were identified, layering dementia, physical, psychosocial, societal and care system factors and highlighting contextual variation. This new knowledge provides the essential basis for the (now underway) development of urgently needed practical and implementable interventions for this underserved population.

Intermittent catheter techniques, strategies and designs for managing long-term bladder conditions.

BACKGROUND: Intermittent catheterisation (IC) is a commonly recommended procedure for people with incomplete bladder emptying. Frequent complications are urinary tract infection (UTI), urethral trauma and discomfort during catheter use. Despite the many designs of intermittent catheter, including different lengths, materials and coatings, it is unclear which catheter techniques, strategies or designs affect the incidence of UTI and other complications, measures of satisfaction/quality of life and cost-effectiveness. This is an update of a Cochrane Review first published in 2007.  OBJECTIVES: To assess the clinical and cost-effectiveness of different catheterisation techniques, strategies and catheter designs, and their impact, on UTI and other complications, and measures of satisfaction/quality of life among adults and children whose long-term bladder condition is managed by intermittent catheterisation. SEARCH METHODS: We searched the Cochrane Incontinence Specialised Register, which contains trials identified from the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, MEDLINE In-Process, MEDLINE Epub Ahead of Print, CINAHL, ClinicalTrials.gov, WHO ICTRP and handsearching of journals and conference proceedings (searched 12 April 2021), the reference lists of relevant articles and conference proceedings, and we attempted to contact other investigators for unpublished data or for clarification. SELECTION CRITERIA: Randomised controlled trials (RCTs) or randomised cross-over trials comparing at least two different catheterisation techniques, strategies or catheter designs. DATA COLLECTION AND ANALYSIS: As per standard Cochrane methodological procedures, two review authors independently extracted data, assessed risk of bias and assessed the certainty of evidence using GRADE. Outcomes included the number of people with symptomatic urinary tract infections, complications such as urethral trauma/bleeding, comfort and ease of use of catheters, participant satisfaction and preference, quality of life measures and economic outcomes. MAIN RESULTS: We included 23 trials (1339 randomised participants), including twelve RCTs and eleven cross-over trials. Most were small (fewer than 60 participants completed), although three trials had more than 100 participants. Length of follow-up ranged from one month to 12 months and there was considerable variation in definitions of UTI. Most of the data from cross-over trials were not presented in a useable form for this review. Risk of bias was unclear in many domains due to insufficient information in the trial reports and several trials were judged to have a high risk of performance bias due to lack of blinding and a high risk of attrition bias. The certainty of evidence was downgraded for risk of bias, and imprecision due to low numbers of participants.    Aseptic versus clean technique We are uncertain if there is any difference between aseptic and clean techniques in the risk of symptomatic UTI because the evidence is low-certainty and the 95% confidence interval (CI) is consistent with possible benefit and possible harm (RR 1.20 95% CI 0.54 to 2.66; one study; 36 participants). We identified no data relating to the risk of adverse events comparing aseptic and clean techniques or participant satisfaction or preference.  Single-use (sterile) catheter versus multiple-use (clean) We are uncertain if there is any difference between single-use and multiple-use catheters in terms of the risk of symptomatic UTI because the certainty of evidence is low and the 95% CI is consistent with possible benefit and possible harm (RR 0.98, 95% CI 0.55, 1.74; two studies; 97 participants). One study comparing single-use catheters to multiple-use catheters reported zero adverse events in either group; no other adverse event data were reported for this comparison. We identified no data for participant satisfaction or preference. Hydrophilic-coated catheters versus uncoated catheters We are uncertain if there is any difference between hydrophilic and uncoated catheters in terms of the number of people with symptomatic UTI because the certainty of evidence is low and the 95% CI is consistent with possible benefit and possible harm (RR 0.89, 95% CI 0.69 to 1.14; two studies; 98 participants). Uncoated catheters probably slightly reduce the risk of urethral trauma and bleeding compared to hydrophilic-coated catheters (RR 1.37, 95% CI 1.01 to 1.87; moderate-certainty evidence). The evidence is uncertain if hydrophilic-coated catheters compared with uncoated catheters has any effect on participant satisfaction measured on a 0-10 scale (MD 0.7 higher, 95% CI 0.19 to 1.21; very low-certainty evidence; one study; 114 participants). Due to the paucity of data, we could not assess the certainty of evidence relating to participant preference (one cross-over trial of 29 participants reported greater preference for a hydrophilic-coated catheter (19/29) compared to an uncoated catheter (10/29)).  AUTHORS' CONCLUSIONS: Despite a total of 23 trials, the paucity of useable data and uncertainty of the evidence means that it remains unclear whether the incidence of UTI or other complications is affected by use of aseptic or clean technique, single (sterile) or multiple-use (clean) catheters, coated or uncoated catheters or different catheter lengths. The current research evidence is uncertain and design and reporting issues are significant. More well-designed trials are needed. Such trials should include analysis of cost-effectiveness because there are likely to be substantial differences associated with the use of different catheterisation techniques and strategies, and catheter designs.

Virus-Sized Gold Nanorods: Plasmonic Particles for Biology.

Plasmons, collective oscillations of conduction-band electrons in nanoscale metals, are well-known phenomena in colloidal gold and silver nanocrystals that produce brilliant visible colors in these materials that depend on the nanocrystal size and shape. Under illumination at or near the plasmon bands, gold and silver nanocrystals exhibit properties that enable fascinating biological applications: (i) the nanocrystals elastically scatter light, providing a straightforward way to image them in complex aqueous environments; (ii) the nanocrystals produce local electric fields that enable various surface-enhanced spectroscopies for sensing, molecular diagnostics, and boosting of bound fluorophore performance; (iii) the nanocrystals produce heat, which can lead to chemical transformations at or near the nanocrystal surface and can photothermally destroy nearby cells. While all the above-mentioned applications have already been well-demonstrated in the literature, this Account focuses on several other aspects of these nanomaterials, in particular gold nanorods that are approximately the size of viruses (diameters of ∼10 nm, lengths up to 100 nm). Absolute extinction, scattering, and absorption properties are compared for gold nanorods of various absolute dimensions, and references for how to synthesize gold nanorods with four different absolute dimensions are provided. Surface chemistry strategies for coating nanocrystals with smooth or rough shells are detailed; specific examples include mesoporous silica and metal-organic framework shells for porous (rough) coatings and polyelectrolyte layer-by-layer wrapping for "smooth" shells. For self-assembled-monolayer molecular coating ligands, the smoothest shells of all, a wide range of ligand densities have been reported from many experiments, yielding values from less than 1 to nearly 10 molecules/nm2 depending on the nanocrystal size and the nature of the ligand. Systematic studies of ligand density for one particular ligand with a bulky headgroup are highlighted, showing that the highest ligand density occurs for the smallest nanocrystals, even though these ligand headgroups are the most mobile as judged by NMR relaxation studies. Biomolecular coronas form around spherical and rod-shaped nanocrystals upon immersion into biological fluids; these proteins and lipids can be quantified, and their degree of adsorption depends on the nanocrystal surface chemistry as well as the biophysical characteristics of the adsorbing biomolecule. Photothermal adsorption and desorption of proteins on nanocrystals depend on the enthalpy of protein-nanocrystal surface interactions, leading to light-triggered alteration in protein concentrations near the nanocrystals. At the cellular scale, gold nanocrystals exert genetic changes at the mRNA level, with a variety of likely mechanisms that include alteration of local biomolecular concentration gradients, changes in mechanical properties of the extracellular matrix, and physical interruption of key cellular processes-even without plasmonic effects. Microbiomes, both organismal and environmental, are the likely first point of contact of nanomaterials with natural living systems; we see a major scientific frontier in understanding, predicting, and controlling microbe-nanocrystal interactions, which may be augmented by plasmonic effects.

Surface Coating Structure and Its Interaction with Cytochrome c in EG6-Coated Nanoparticles Varies with Surface Curvature.

The composition, orientation, and conformation of proteins in biomolecular coronas acquired by nanoparticles in biological media contribute to how they are identified by a cell. While numerous studies have investigated protein composition in biomolecular coronas, relatively little detail is known about how the nanoparticle surface influences the orientation and conformation of the proteins associated with them. We previously showed that the peripheral membrane protein cytochrome c adopts preferred poses relative to negatively charged 3-mercaptopropionic acid (MPA)-gold nanoparticles (AuNPs). Here, we employ molecular dynamics simulations and complementary experiments to establish that cytochrome c also assumes preferred poses upon association with nanoparticles functionalized with an uncharged ligand, specifically ω-(1-mercaptounde-11-cyl)hexa(ethylene glycol) (EG6). We find that the display of the EG6 ligands is sensitive to the curvature of the surface-and, consequently, the effective diameter of the nearly spherical nanoparticle core-which in turn affects the preferred poses of cytochrome c.

Gold nanorod impact on mechanical properties of stretchable hydrogels.

Double-network hydrogels have attracted much attention because of their superior mechanical properties, which are more similar to rubbers and soft tissues than classic hydrogels. In this report, plasmonic gold nanorods (AuNRs) were incorporated into a stretchable double-network hydrogel, composed of alginate and acrylamide. The impact of gold nanorod concentration and surface chemistry on bulk mechanical properties such as Young's modulus and elongation at break was investigated. AuNRs with three different surface chemistries, cetyltrimethylammonium bromide, thiolated poly(ethylene glycol), and 11-mercaptoundecanoic acid were successfully dispersed into alginate/polyacrylamide hydrogels. The AuNR-loaded hydrogels could be reversibly stretched, leading to AuNR reversible alignment along the stretch direction as judged by polarized optical spectroscopy. With the proper surface chemistry, hydrogel nanorod composites were able to be stretched to more than 3000% their initial length without fracturing. These results show that plasmonic gold nanorods can be well dispersed in multi-component polymer systems, certain surface chemistries can enhance the bulk mechanical properties, and AuNR orientation can be controlled through varying strains on the matrix.

Antibiotic Treatments and Patient Outcomes in Necrotizing Enterocolitis.

OBJECTIVE: This study aimed to examine the impact of different antibiotic treatments on necrotizing enterocolitis (NEC) outcomes. STUDY DESIGN: Patient outcomes, including total parenteral nutrition and hospitalization durations, abdominal surgeries, intestinal strictures, and mortality data, were analyzed and compared by various antibiotic groups and treatment durations for 160 NEC patients managed at the Women and Children's Hospital of Buffalo between 2008 and 2016. RESULTS: Fourteen different antibiotics were used for NEC, most commonly ampicillin, gentamicin, and metronidazole (AGM). Medical (vs. surgical) NEC patients more likely received AGM (37 vs. 6%, p < 0.001). Surgical (vs. medical) NEC patients more likely received vancomycin (80 vs. 30%, p < 0.001) and antipseudomonal agents (69 vs. 15%, p < 0.001). For medical NEC there were no outcome differences between patients receiving only AGM versus those receiving other treatments; in patients receiving AGM, there were no outcome differences in durations of ≤10 days versus longer courses. CONCLUSION: Antibiotic use for NEC varies substantially without definite outcome differences. Particularly with medical NEC, AGM for ≤10 days had comparable outcomes to other treatments. In light of growing concern for short and longer term adverse effects with early-life antibiotic exposure, narrow-spectrum and shorter course NEC treatment may be preferred.

Development and randomised controlled trial of a Continence Product Patient Decision Aid for men postradical prostatectomy.

AIMS AND OBJECTIVES: To develop and evaluate an evidence-based Continence Product Patient Decision Aid (CP-PDA) to reduce decisional conflict and support continence product choice for men postradical prostatectomy. BACKGROUND: In 2018, 1.3 million men globally were diagnosed with prostate cancer. A common treatment is radical prostatectomy, usually leading to sudden onset of urinary incontinence. For people experiencing incontinence, products to contain leakage are fundamental to health-related quality of life, but many product users and healthcare professionals are unaware of available options. No evidence-based guidance on choosing products exists despite known physical and psychological burdens of poorly managed leakage (e.g. isolation, anxiety, depression, skin damage). DESIGN AND METHODS: 4 phases, underpinned by international decision aid guidance. Evidence/expert opinion: Literature review; consultation with specialist continence clinicians (n = 7) to establish evidence base. Prototype: CP-PDA developed with continence specialist (n = 7) feedback. Alpha testing (stakeholders): CP-PDA materials were provided to expert patients (n = 10) and clinicians (n = 11) to assess content/presentation. Beta testing (field) following CONSORT guidelines, registered NIHR CPMS 31077: Men (n = 50) postradical prostatectomy randomised to evaluate usability and decision-making using the Decisional Conflict Scale compared with usual care. RESULTS: An algorithm differentiating patients by mobility, dependency, cognitive impairment and type/level of leakage, leading to 12 user groups, was developed. For each group, an option table and associated product information sheets guide product choice. Total Decisional Conflict Score for men using the CP-PDA was significantly better than for men without. CP-PDA users reported greater confidence in product knowledge and choice. CONCLUSION: This is the first evidence-based CP-PDA, developed using an internationally recognised method. Compared to usual care, it significantly reduced decisional conflict for men choosing continence products postprostatectomy. RELEVANCE TO CLINICAL PRACTICE: The CP-PDA provides nurses with the first comprehensive, evidence-based intervention to help postprostatectomy men in complex continence product choices. An online version is available: www.continenceproductadvisor.org.