Characterization and Cellular Toxicity Studies of Commercial Manganese Oxide Nanoparticles.

Manganese oxide nanoparticles (MnOx NPs) are finding applications in several environmentally important areas such as farming and energy storage. MnOx NPs span a range of metal oxidation states that open up a wide range of applications in catalysis as well. As a result, it is important to understand how such materials can impact human health through incidental exposure. In this study, we examined a range of commercially available Mn2O3 NPs and compared our characterization data to those supplied by manufacturers. Discrepancies were noted and then measured values were used to assess the biological impact of these materials on three mammalian cell lines-A549, HepG2 and J774A.1 cells. Cell toxicity assays showed that all Mn2O3 particles exhibited cytotoxic effects that may be correlated, at least in part, to the production of reactive oxygen species. All eight nanoforms also activated caspase 3 but not caspase 1, although the magnitude of these changes varied greatly between materials.

Examining adaptive models of care implemented in hospital ICUs during the COVID-19 pandemic: a qualitative study.

BACKGROUND: The emergence of the COVID-19 pandemic led to an increased demand for hospital beds, which in turn led to unique changes to both the organisation and delivery of patient care, including the adoption of adaptive models of care. Our objective was to understand staff perspectives on adaptive models of care employed in intensive care units (ICUs) during the pandemic. METHODS: We interviewed 77 participants representing direct care staff (registered nurses) and members of the nursing management team (nurse managers, clinical educators and nurse practitioners) from 12 different ICUs. Thematic analysis was used to code and analyse the data. RESULTS: Our findings highlight effective elements of adaptive models of care, including appreciation for redeployed staff, organising aspects of team-based models and ICU culture. Challenges experienced with the pandemic models of care were heightened workload, the influence of experience, the disparity between model and practice and missed care. Finally, debriefing, advanced planning and preparation, the redeployment process and management support and communication were important areas to consider in implementing future adaptive care models. CONCLUSION: The implementation of adaptive models of care in ICUs during the COVID-19 pandemic provided a rapid solution for staffing during the surge in critical care patients. Findings from this study highlight some of the challenges of implementing redeployment as a staffing strategy, including how role clarity and accountability can influence the adoption of care delivery models, lead to workarounds and contribute to adverse patient and nurse outcomes.

A Multi-factor Analysis of Revision in Total Hip Replacement Using the Collarless-Polished-Tapered Stems with Different Cups.

OBJECTIVE: Collarless-polished-tapered (CPT) stems have been widely used in total hip replacement (THR). Given that various types of cups are combined with CPT in clinical practice, however, what cup type performs the best for use with CPT is still unclear. This study aimed to investigate the effects of three types of commonly used cups with CPT on revision and survival life using multi-factor analysis. METHODS: This study is a cohort study using the data between October 1998 to September 2021. The data of THR patients with ZCA All-poly Acetabular Cup, Continuum Acetabular System, and Trilogy Acetabular System with CPT were collected from several hospitals in the UK. The patients aged from 20 to 97 (n = 5981, 2345 male and 3636 female). Age, gender, body mass index, diagnosis, surgeon grade, cup material, cup size, surgical approach, survival life, complications, and Harris hip scores (HHS) were analyzed in relation to revision status. SPSS statistical software was used to analyze the relationship among various factors. The main statistical methods included chi-square with cross tables, analysis of variance (ANOVA) and survival analysis. RESULTS: The results in relation to HHS shows that the continuum cup has the best outcome in the postoperative period of 1 and 5 years (1 year = 90.7, 5 years = 91.3; P < 0.001); the Trilogy cup was the second (1 year = 88.4, 5 years = 87.3; P < 0.001); and the ZCA cup was the third (1 year = 84.6, 5 years = 82.4; P < 0.001). However, the Trilogy cup performed the best regarding survival life on revision while the Continuum cup was the worst. CONCLUSION: When the CPT stem is combined with different cups, the trilogy cup shows the best characteristics in terms of survival trends with revision ratios compared with the continuum and ZCA cups, and is therefore recommended by this study.

Barriers to, and facilitators of, eHealth utilisation by parents of high-risk newborn infants in the NICU: a scoping review protocol.

INTRODUCTION: Parental presence in the neonatal intensive care unit (NICU) has been demonstrated to enhance infant growth and development, reduce parental anxiety and stress and strengthen parent-infant bonding. Since eHealth technology emerged, research on its utilisation in NICUs has risen substantially. There is some evidence that incorporating such technologies in the NICU can reduce parental stress and enhance parent confidence in caring for their infant.Several countries, including China, restrict parental attendance in NICUs, citing infection control challenges, issues of privacy and confidentiality and perceived additional workload for healthcare professionals. Due to COVID-19 pandemic-related shortages of personal protective equipment and uncertain mode of transmission, many NICUs around the world closed to parental visiting and engagement in neonatal care.There is anecdotal evidence that, given pandemic-related restrictions, eHealth technologies, have increasingly been used in NICUs as a potential substitute for in-person parental presence.However, the constraints and enablers of technologies in these situations have not been exhaustively examined. This scoping review aims to update the literature on eHealth technology utilisation in the NICU and to explore the literature on the challenges and facilitators of eHealth technology implementation to inform future research. METHODS AND ANALYSIS: The five-stage Arksey and O'Malley methodological framework and the Joanna Briggs Institute scoping review methodology will serve as the foundation for this scoping review. Eight databases will be searched for the relevant literature published between January 2000 and August 2022 in either English or Chinese. Grey literature will be manually searched. Data extraction and eligibility screening will be carried out by two impartial reviewers. There will be periods of both quantitative and qualitative analysis. ETHICS AND DISSEMINATION: Since all data and information will be taken from publicly accessible literature, ethical approval would not be necessary. A peer-reviewed publication will be published with the results of this scoping review. TRIAL REGISTRATION NUMBER: This scoping review protocol was registered in Open Science Framework and can be found here: https://osf.io/AQV5P/.

Physical restraint practices in an adult intensive care unit: A prospective observational study.

AIM AND OBJECTIVES: To conduct a diagnostic evaluation of physical restraint practice using the integrated-Promoting Action on Research Implementation in Health Services (i-PARIHS) framework. BACKGROUND: Evidence indicates that physical restraints are associated with adverse physical, emotional and psychological sequelae and do not consistently prevent intensive care unit (ICU) patient-initiated device removal. Nevertheless, physical restraints continue to be used extensively in ICUs both in Canada and internationally. Implementation science frameworks have not been previously used to diagnose, develop and guide the implementation of restraint minimisation interventions. DESIGN: A prospective observational study of restrained patients in a 20-bed, academic ICU in Toronto, Canada. METHODS: Data collection methods included patient observation, electronic medical record review, and verbal check with the point-of-care nurses. Data were collected pertaining to framework domains of unit culture (restraint application/removal), evaluation capacity (documentation) and leadership (rounds discussion). The reporting of this study followed the STROBE guidelines. RESULTS: A total of 102 restrained patients, 67 (66%) male and mean age 58 years (SD 1.92), were observed. All observed devices were wrist restraints. Restraint application and removal time was verified in 83 and 57 of 102 patients respectively. At application, 96.4% were mechanically ventilated and 71% sedated/unarousable. Nurses confirmed 71% were prophylactically restrained; 7.2% received restraint alternatives. Restraint removal occurred after interprofessional team rounds (87%), during daytime (79%) and following extubation (52.6%). Of the 923 discrete patient observation of physical restraint use, 691 (75%) were not documented. Of the 30 daytime interprofessional team rounds reviewed, physical restraint was discussed at 3 (10%). CONCLUSION: In this single-centre study, a culture of prophylactic physical restraint was observed. Future facilitation of restraint minimisation warrants theoretically informed implementation strategies including leadership involvement to advance interprofessional collaboration. RELEVANCE TO CLINICAL PRACTICE: The findings draw attention to the importance of a preliminary diagnostic study of the context prior to designing, and implementing, a physical restraint minimisation intervention.

Interprofessional intensive care unit (ICU) team perspectives on physical restraint practices and minimization strategies in an adult ICU: A qualitative study of contextual influences.

BACKGROUND: Guidelines advocate for minimization of physical restraint (PR) use in intensive care units (ICU). Interprofessional team perspectives on PR practices can inform the design and implementation of successful PR minimization interventions. AIM: To identify ICU staff perspectives of contextual influences on PR practices and minimization strategies. STUDY DESIGN: A qualitative descriptive study in a single ICU in Toronto, Canada. METHODS: One-on-one semi-structured interviews were conducted with 14 ICU staff. A deductive content analysis of interviews was undertaken using the integrated-Promoting Action on Research Implementation in Health Services (i-PARIHS) framework. RESULTS: Five themes were developed: risk-averse culture, leadership, practice monitoring and feedback processes, environmental factors, and facilitation. Participants described a risk-averse culture where prophylactic application of PR for intubated patients was used to prevent unplanned extubation thereby avoiding blame from colleagues. Perceived absence of leadership and interprofessional team involvement situated nurses as the primary decision-maker for restraint application and removal. Insufficient monitoring of restraint practices, lack of access to restraint alternatives, and inability to control environmental contributors to delirium and agitation further increased PR use. Recommendations as to how to minimize restraint use included a nurse facilitator to advance leadership-team collaboration, availability of restraints alternatives, and guidance on situations for applying and removing restraints. CONCLUSIONS: This analysis of contextual influences on PR practices and minimization using the i-PARIHS framework revealed potentially modifiable barriers to successful PR minimization, including a lack of leadership involvement, gaps in practice monitoring, and collaborative decision-making processes. A team approach to changing behaviour and culture should be considered for successful implementation and sustainability of PR minimization. RELEVANCE TO PRACTICE: The establishment of an interprofessional facilitation team that addresses risk-averse culture and promotes collaboration among ICU stakeholders will be crucial to the success of any approach to restraint minimization.

The impact of breast milk feeding on early brain development in preterm infants in China: An observational study.

BACKGROUND: The prevailing consensus from large epidemiological studies is that breastfeeding is associated with improved IQ and cognitive functioning in later childhood and adolescence. Current research is exploring the association between breastfeeding and early brain development in preterm infants. OBJECTIVE: To explore the differences in brain gray matter between breastmilk-fed and formula-fed preterm infants using structural and functional magnetic resonance imaging. METHODS: A convenience sample of breastmilk-fed preterm infants(n = 34) and formula-fed infants (n = 22) aged approximately 32 weeks. At near term-equivalent age, MR scanning was performed. Gray matter structural and functional differences between the two groups were assessed using MATLAB software for voxel-based morphometry (VBM) and amplitude of low-frequency fluctuation (ALFF) analysis. RESULTS: Maternal and neonatal demographic characteristics showed no significant difference between the two groups. Breastmilk-fed infants had greater regional gray matter volume on MRI than formula-fed infants in multiple brain regions, including the bilateral frontal lobe (BA11, BA46), right temporal lobe (BA37), and left caudate nucleus, at a statistical threshold of p<0.01 (AlphaSim corrected) with a cluster size of >40 voxels. Compared with formula-fed infants, breastmilk-fed infants showed increased brain activation on fMRI in the right superior temporal gyrus (BA41). CONCLUSION: Breastmilk-fed infants had greater regional gray matter development and increased regional gray matter function compared with formula-fed infants at near term-equivalent age, suggesting breastmilk feeding in the early period after birth may have some degree of influence on early brain development in preterm infants.

Physical Characterization and Cellular Toxicity Studies of Commercial NiO Nanoparticles.

Nickel oxide (NiO) nanoparticles from several manufacturers with different reported sizes and surface coatings were characterized prior to assessing their cellular toxicity. The physical characterization of these particles revealed that sizes often varied from those reported by the supplier, and that particles were heavily agglomerated when dispersed in water, resulting in a smaller surface area and larger hydrodynamic diameter upon dispersion. Cytotoxicity testing of these materials showed differences between samples; however, correlation of these differences with the physical properties of the materials was not conclusive. Generally, particles with higher surface area and smaller hydrodynamic diameter were more cytotoxic. While all samples produced an increase in reactive oxygen species (ROS), there was no correlation between the magnitude of the increase in ROS and the difference in cytotoxicity between different materials.

Surface chemistry of metal oxide nanoparticles: NMR and TGA quantification.

Surface functionalization is widely used to control the behavior of nanomaterials for a range of applications. However, methods to accurately quantify surface functional groups and coatings are not yet routinely applied to nanomaterial characterization. We have employed a combination of quantitative NMR (qNMR) and thermogravimetric analysis (TGA) to address this problem for commercial cerium, nickel, and iron oxide nanoparticles (NPs) that have been modified to add functional coatings with (3-aminopropyl)triethoxysilane (APTES), stearic acid, and polyvinylpyrrolidone (PVP). The qNMR method involves quantification of material that is released from the NPs and quantified in the supernatant after removal of NPs. Removal of aminopropylsilanes was accomplished by basic hydrolysis whereas PVP and stearic acid were removed by ligand exchange using sodium hexametaphosphate and pentadecafluorooctanoic acid, respectively. The method accuracy was confirmed by analysis of NPs with a known content of surface groups. Complementary TGA studies were carried out in both air and argon atmosphere with FT-IR of evolved gases in argon to confirm the identity of the functional groups. TGA measurements for some unfunctionalized samples show mass loss due to unidentified components which makes quantification of functional groups in surface-modified samples less reliable. XPS provides information on the presence of surface contaminants and the level of surface hydroxylation for selected samples. Despite the issues associated with accurate quantification using TGA, the TGA estimates agree reasonably well with the qNMR data for samples with high surface loading. This study highlights the issues in analysis of commercial nanomaterials and is an advance towards the development of generally applicable methods for quantifying surface functional groups.

Implementation of nonpharmacologic physical restraint minimization interventions in the adult intensive care unit: A scoping review.

OBJECTIVE: To identify the elements informing the successful implementation of nonpharmacologic physical restraint minimization interventions in adult intensive care unit patients. To map those elements to innovation, context, recipients and facilitation domains of the integrated-Promoting Action on Research Implementation in Health Services (i-PARIHS) framework and to describe the outcomes of those interventions. METHODOLOGY: A scoping review of studies published in English reporting on restraint minimization interventions in adult intensive care units. We searched seven databases (MEDLINE, CIHAHL, Embase, Web of Science, Cochrane Library, PROSPERO and Joanna Briggs) from inception to 2021. Two authors independently screened articles for inclusion, extracted study characteristics and mapped intervention data to the i-PARIHS domains. RESULTS: Seven studies met inclusion criteria. Innovations comprised multicomponent interventions including education, decision aids/protocols and restraint alternatives. No studies utilised an implementation science framework to diagnose the baseline practice context. A commonly reported barrier to restraint minimization was a risk averse culture. Change was mostly driven by the external context (i.e. national regulations). Overall, nurses were the primary facilitators and recipients of practice change. Outcomes were changes in restraint incidence and prevalence abstracted from the medical record. However, no study validated the accuracy of restraint documentation. All studies documented an initial decrease in physical restraint use, but no long-term results were reported. CONCLUSION: Restraint minimization intervention studies report nurse-facilitated multicomponent interventions and short-term practice change. Future restraint minimization research incorporating implementation science frameworks, interprofessional teams and patient/family perspectives is warranted.

Interlaboratory Comparison on the Quantification of Total and Accessible Amine Groups on Silica Nanoparticles with qNMR and Optical Assays.

Risk assessment of nanomaterials requires not only standardized toxicity studies but also validated methods for nanomaterial surface characterization with known uncertainties. In this context, a first bilateral interlaboratory comparison on surface group quantification of nanomaterials is presented that assesses different reporter-free and labeling methods for the quantification of the total and accessible number of amine functionalities on commercially available silica nanoparticles that are widely used in the life sciences. The overall goal of this comparison is the identification of optimum methods as well as achievable measurement uncertainties and the comparability of the results across laboratories. We also examined the robustness and ease of implementation of the applied analytical methods and discussed method-inherent limitations. In summary, this comparison presents a first step toward the eventually required standardization of methods for surface group quantification.

Comprehensive framework for human health risk assessment of nanopesticides.

Nanopesticides are not only in an advanced state of research and development but have started to appear on the market. Industry and regulatory agencies need a consolidated and comprehensive framework and guidance for human health risk assessments. In this perspective we develop such a comprehensive framework by exploring two case studies from relevant product types: an active ingredient delivered with a nanocarrier system, and a nanoparticle as an active ingredient. For a nanocarrier system, three entities are tracked during the assessment: the nanocarrier-active ingredient complex, the empty nanocarrier remaining after the complete release of the active ingredient, and the released active ingredient. For the nanoparticle of pure active ingredient, only two entities are relevant: the nanoparticle and the released ions. We suggest important adaptations of the existing pesticide framework to determine the relevant nanopesticide entities and their concentrations for toxicity testing. Depending on the nature of the nanopesticides, additional data requirements, such as those pertaining to durability in biological media and potential for crossing biological barriers, have also been identified. Overall, our framework suggests a tiered approach for human health risk assessment, which is applicable for a range of nanopesticide products to support regulators and industry in making informed decisions on nanopesticide submissions. Brief summaries of suitable methods including references to existing standards (if available) have been included together with an analysis of current knowledge gaps. Our study is an important step towards a harmonized approach accepted by regulatory agencies for assessing nanopesticides.

Kinematic 3-D motion analysis of shoulder resurfacing hemiarthroplasty - An objective assessment method.

Shoulder replacement is indicated in the treatment of pain due to osteoarthritis. Few studies have objectively assessed range of motion (RoM) gains at different post-operative time points. This is a prospective 3D motion analysis study to objectively quantify RoM changes at multiple time points following shoulder resurfacing arthroplasty (SRA) for primary gleno-humeral osteoarthritis, comparing it with clinically measured RoM. Clinical assessment, Visual Analog Scale (VAS) pain score, Constant-Morley (CS) and Oxford Shoulder Score (OSS) were recorded. Motion analysis was performed for RoM and three activities of daily living tasks (ADL), pre-operatively and post-operatively at 4 and 12 months. Nineteen shoulders in fifteen patients were included. The mean age was 72 years (range 52-84). There were significant improvements in external and internal rotation, ability to place the hand behind the head and reach the fifth lumbar vertebra, at 4 months on clinical examination and kinematic analysis with no further improvements at 12 months. There was significant improvement in abduction at 4 months with further improvement at 12 months, which was significantly more than noted on clinical assessment. In contrast, kinematic analysis showed a reduction in flexion between 4 and 12 months, while clinically there appeared to be an improvement between these time periods. This is the first study to prospectively utilise objective kinematic 3-D motion analysis in addition to clinical measurements and outcome scores, to investigate the outcome of resurfacing arthroplasty at multiple time points after surgery, providing an understanding into the trends of change in these parameters.

Particle Size Distributions for Cellulose Nanocrystals Measured by Transmission Electron Microscopy: An Interlaboratory Comparison.

Particle size is a key parameter that must be measured to ensure reproducible production of cellulose nanocrystals (CNCs) and to achieve reliable performance metrics for specific CNC applications. Nevertheless, size measurements for CNCs are challenging due to their broad size distribution, irregular rod-shaped particles, and propensity to aggregate and agglomerate. We report an interlaboratory comparison (ILC) that tests transmission electron microscopy (TEM) protocols for image acquisition and analysis. Samples of CNCs were prepared on TEM grids in a single laboratory, and detailed data acquisition and analysis protocols were provided to participants. CNCs were imaged and the size of individual particles was analyzed in 10 participating laboratories that represent a cross section of academic, industrial, and government laboratories with varying levels of experience with imaging CNCs. The data for each laboratory were fit to a skew normal distribution that accommodates the variability in central location and distribution width and asymmetries for the various datasets. Consensus values were obtained by modeling the variation between laboratories using a skew normal distribution. This approach gave consensus distributions with values for mean, standard deviation, and shape factor of 95.8, 38.2, and 6.3 nm for length and 7.7, 2.2, and 2.9 nm for width, respectively. Comparison of the degree of overlap between distributions for individual laboratories indicates that differences in imaging resolution contribute to the variation in measured widths. We conclude that the selection of individual CNCs for analysis and the variability in CNC agglomeration and staining are the main factors that lead to variations in measured length and width between laboratories.

Characterization of Commercial Metal Oxide Nanomaterials: Crystalline Phase, Particle Size and Specific Surface Area.

Physical chemical characterization of nanomaterials is critical to assessing quality control during production, evaluating the impact of material properties on human health and the environment, and developing regulatory frameworks for their use. We have investigated a set of 29 nanomaterials from four metal oxide families (aluminum, copper, titanium and zinc) with a focus on the measurands that are important for the basic characterization of dry nanomaterials and the determination of the dose metrics for nanotoxicology. These include crystalline phase and crystallite size, measured by powder X-ray diffraction, particle shape and size distributions from transmission electron microscopy, and specific surface area, measured by gas adsorption. The results are compared to the nominal data provided by the manufacturer, where available. While the crystalline phase data are generally reliable, data on minor components that may impact toxicity is often lacking. The crystal and particle size data highlight the issues in obtaining size measurements of materials with broad size distributions and significant levels of aggregation, and indicate that reliance on nominal values provided by the manufacturer is frequently inadequate for toxicological studies aimed at identifying differences between nanoforms. The data will be used for the development of models and strategies for grouping and read-across to support regulatory human health and environmental assessments of metal oxide nanomaterials.

Acellular oxidative potential assay for screening of amorphous silica nanoparticles.

Silica nanoparticles (SiNPs) are used in a wide range of consumer products, engineering and medical applications, with likelihood of human exposure and potential health concerns. It is essential to generate toxicity information on SiNP forms and associated physicochemical determinants to conduct risk assessment on these new materials. To address this knowledge gap, we screened a panel of custom synthesized, well-characterized amorphous SiNPs pristine and surface-modified (-C3-COOH, -C11-COOH, -NH2, -PEG) of 5 different sizes: (15, 30, 50, 75, 100 nm) for their oxidative potential using an acellular assay. The assay is based on oxidation of dithiothreitol (DTT) by reactive oxygen species and can serve as a surrogate test for oxidative stress. These materials were characterized for size distribution, aggregation, crystallinity, surface area, surface modification, surface charge and metal content. Tests for association between oxidative potential of SiNPs and their physicochemical properties were carried out using analysis of variance and correlation analyses. These test results suggest that the size of amorphous SiNPs influenced their oxidative potential irrespective of the surface modification, with 15 nm exhibiting relatively higher oxidative potential compared to the other sizes. Furthermore, SiNP surface area, surface modification and agglomeration in solution also appeared to affect oxidative potential of these SiNPs. These findings indicate that physicochemical properties are critical in influencing the oxidative behaviour of amorphous SiNPs, with potential to trigger cellular oxidative stress and thus toxicity, when exposed. This information advances our understanding of potential toxicities of these amorphous SiNPs and supports risk assessment efforts and the design of safer forms of silica nanomaterials.

A Multi-Method Approach for Quantification of Surface Coatings on Commercial Zinc Oxide Nanomaterials.

Surface functionalization is a key factor for determining the performance of nanomaterials in a range of applications and their fate when released to the environment. Nevertheless, it is still relatively rare that surface groups or coatings are quantified using methods that have been carefully optimized and validated with a multi-method approach. We have quantified the surface groups on a set of commercial ZnO nanoparticles modified with three different reagents ((3-aminopropyl)-triethoxysilane, caprylsilane and stearic acid). This study used thermogravimetric analysis (TGA) with Fourier transform infrared spectroscopy (FT-IR) of evolved gases and quantitative solution 1H nuclear magnetic resonance (NMR) for quantification purposes with 13C-solid state NMR and X-ray photoelectron spectroscopy to confirm assignments. Unmodified materials from the same suppliers were examined to assess possible impurities and corrections. The results demonstrate that there are significant mass losses from the unmodified samples which are attributed to surface carbonates or residual materials from the synthetic procedure used. The surface modified materials show a characteristic loss of functional group between 300-600 °C as confirmed by analysis of FT-IR spectra and comparison to NMR data obtained after quantitative release/extraction of the functional group from the surface. The agreement between NMR and TGA estimates for surface loading is reasonably good for cases where the functional group accounts for a relatively large fraction of the sample mass (e.g., large groups or high loading). In other cases TGA does not have sufficient sensitivity for quantitative analysis, particularly when contaminants contribute to the TGA mass loss. X-ray photoelectron spectroscopy and solid state NMR for selected samples provide support for the assignment of both the functional groups and some impurities. The level of surface group loading varies significantly with supplier and even for different batches or sizes of nanoparticles from the same supplier. These results highlight the importance of developing reliable methods to detect and quantify surface functional groups and the importance of a multi-method approach.

Quantification of surface functional groups on silica nanoparticles: comparison of thermogravimetric analysis and quantitative NMR.

Thermogravimetric analysis (TGA) coupled with evolved gas analysis-FT-IR has been examined as a potential method to study the functional group content for surface modified silica nanoparticles. A comparison with a quantitative solution NMR method based on analysis of groups released after dissolution of the silica matrix is used to provide benchmark data for comparison and to assess the utility and limitations of TGA. This study focused primarily on commercially available silicas and tested whether it was possible to use a correction based on bare silica to account for the significant mass loss that occurs due to condensation of surface hydroxyl groups and loss of matrix-entrapped components at temperatures above ∼200 °C. Although this approach has been used successfully in the literature for in-house prepared samples, it was problematic for commercial silicas prepared by the Stöber method. For these materials the agreement between estimates from qNMR and TGA mass loss was poor in many cases. However much better agreement was observed for samples for which the mass loss above 200 °C is relatively low, such as non-porous silica, or samples for which the mass fraction of functional group is large (e.g., high molecule weight groups or multilayers). FT-IR was useful in identifying the likely structure of the components lost from the surface at various temperatures and in some cases provided evidence of contaminants in the sample. Nevertheless, in other cases correlation of thermograms and FT-IR with NMR data was necessary, particularly for samples where multi-step modification of the silica surface results in incomplete functionalization that gives a mixture of products. Overall the results indicate that TGA provides reliable results for silicas of low porosity or those for which the functional group accounts for a significant fraction of the total sample mass. It is also suitable as a supplementary or screening technique to indicate the presence of coatings or covalent surface modification, prior to applying other techniques or for routine analyses where sensitivity is not critical.

Quantification of amine functional groups on silica nanoparticles: a multi-method approach.

Surface chemistry is an important factor for quality control during production of nanomaterials and for controlling their behavior in applications and when released into the environment. Here we report a comparison of four methods for quantifying amine functional groups on silica nanoparticles (NPs). Two colorimetric assays are examined, ninhydrin and 4-nitrobenzaldehyde, which are convenient for routine analysis and report on reagent accessible amines. Results from the study of a range of commercial NPs with different sizes and surface loadings show that the assays account for 50-100% of the total amine content, as determined by dissolution of NPs under basic conditions and quantification by solution-state 1H NMR. To validate the surface quantification by the colorimetric assays, the NPs are modified with a trifluoromethylated benzaldehyde probe to enhance sensitivity for quantitative 19F solid state NMR and X-ray photoelectron spectroscopy (XPS). Good agreement between the assays and the determination from solid-state NMR is reinforced by elemental ratios from XPS, which indicate that in most cases the difference between total and accessible amine content reflects amines that are outside the depth probed by XPS. Overall the combined results serve to validate the relatively simple colorimetric assays and indicate that the reactions are efficient at quantifying surface amines, by contrast to some other covalent modifications that have been employed for functional group quantification.

High response and re-infection rates among people who inject drugs treated for hepatitis C in a community needle and syringe programme.

To achieve WHO hepatitis C virus (HCV) elimination targets by 2030, mathematical models suggest there needs to be significant scale-up of treatment among people who inject drugs (PWID). We tested whether people who actively inject drugs can be recruited and treated successfully through a community needle and syringe programme (NSP), and assessed rates of re-infection. 105 HCV RNA positive participants were enrolled prospectively. Participants were recruited from the largest NSP in Dundee over 42 months. 94/105 individuals commenced treatment. Genotype 1 (G1) individuals (n = 37) were treated with peg-interferon+ribavirin+Simepravir/Telaprevir. Genotype 2/3 (G2/3) (n = 57) received peg-interferon+ribavirin. Weekly study visits took place within the NSP. Mean age of participants was 34.0 years (SD 6.9), 71.3% (61/94) were male. One in five (20/94) participants were homeless. 68.1% (64/94) were on OST (opiate substitution therapy) at enrolment; participants injected median 6.5 times/wk. In terms of clinical outcomes, >80% treatment adherence was 71.3% (67/94). There was no difference in SVR-12 rates by genotype: 81.0% (30/37) for G1 and 82.5% (47/55) for G2/3. At 18 months post-treatment, 15/77 participants were reinfected, followed up over 69.8 person-years, yielding a re-infection rate of 21.5/100 person-years (95% CI 13.00-35.65). This trial demonstrates that HCV treatment can be delivered successfully to the target population of treatment as prevention strategies. We report higher rates of re-infection than existing estimates among PWID. Scale-up of HCV treatment should be pursued alongside a comprehensive programme of harm reduction interventions to help minimize re-infection and reduce HCV transmission.