Using small angle x-ray scattering to examine the aggregation mechanism in silica nanoparticle-based ambigels for improved optical clarity.

Silica-based aerogels are a promising low-cost solution for improving the insulation efficiency of single-pane windows and reducing the energy consumption required for space heating and cooling. Two key material properties required are high porosity and small pore sizes, which lead to low thermal conductivity and high optical transparency, respectively. However, porosity and pore size are generally directly linked, where high porosity materials also have large pore sizes. This is unfavorable as large pores scatter light, resulting in reduced transmittance in the visible regime. In this work, we utilized preformed silica colloids to explore methods for reducing pore size while maintaining high porosity. The use of preformed colloids allows us to isolate the effect of solution conditions on porous gel network formation by eliminating simultaneous nanoparticle growth and aggregation found when using typical sol-gel molecular-based silica precursors. Specifically, we used in situ synchrotron-based small-angle x-ray scattering during gel formation to better understand how pH, concentration, and colloid size affect particle aggregation and pore structure. Ex situ characterization of dried gels demonstrates that peak pore widths can be reduced from 15 to 13 nm, accompanied by a narrowing of the overall pore size distribution, while maintaining porosities of 70%-80%. Optical transparency is found to increase with decreasing pore sizes while low thermal conductivities ranging from 95 +/- 13 mW/m K are maintained. Mechanical performance was found to depend primarily on effective density and did not show a significant dependence on solution conditions. Overall, our results provide insights into methods to preserve high porosity in nanoparticle-based aerogels while improving optical transparency.

Randomized, placebo controlled phase I trial of the safety, pharmacokinetics, pharmacodynamics and acceptability of a 90 day tenofovir plus levonorgestrel vaginal ring used continuously or cyclically in women: The CONRAD 138 study.

Multipurpose prevention technologies (MPTs), which prevent sexually transmitted infection(s) and unintended pregnancy, are highly desirable to women. In this randomized, placebo-controlled, phase I study, women used a placebo or tenofovir (TFV) and levonorgestrel (LNG) intravaginal ring (IVR), either continuously or cyclically (three, 28-day cycles with a 3 day interruption in between each cycle), for 90 days. Sixty-eight women were screened; 47 were randomized to 4 arms: TFV/LNG or placebo IVRs used continuously or cyclically (4:4:1:1). Safety was assessed by adverse events and changes from baseline in mucosal histology and immune mediators. TFV concentrations were evaluated in multiple compartments. LNG concentration was determined in serum. Modeled TFV pharmacodynamic antiviral activity was evaluated in vaginal and rectal fluids and cervicovaginal tissue ex vivo. LNG pharmacodynamics was assessed with cervical mucus quality and anovulation. All IVRs were safe with no serious adverse events nor significant changes in genital tract histology, immune cell density or secreted soluble proteins from baseline. Median vaginal fluid TFV concentrations were >500 ng/mg throughout 90d. TFV-diphosphate tissue concentrations exceeded 1,000 fmol/mg within 72hrs of IVR insertion. Mean serum LNG concentrations exceeded 200 pg/mL within 2h of TFV/LNG use, decreasing quickly after IVR removal. Vaginal fluid of women using TFV-containing IVRs had significantly greater inhibitory activity (87-98% versus 10% at baseline; p<0.01) against HIV replication in vitro. There was a >10-fold reduction in HIV p24 antigen production from ectocervical tissues after TFV/LNG exposure. TFV/LNG IVR users had significantly higher rates of anovulation, lower Insler scores and poorer/abnormal cervical mucus sperm penetration. Most TFV/LNG IVR users reported no change in menstrual cycles or fewer days of and/or lighter bleeding. All IVRs were safe. Active rings delivered high TFV concentrations locally. LNG caused changes in cervical mucus, sperm penetration, and ovulation compatible with contraceptive efficacy. Trial registration: ClinicalTrials.gov #NCT03279120.

Acceptability of a Long-Acting, Multipurpose Vaginal Ring: Findings from a Phase I Trial in the U.S. and Dominican Republic.

Background: Women worldwide face risks from pregnancy, HIV, and other sexually transmitted infections (STIs). To date, highly effective contraceptive methods provide no HIV/STI protection, and HIV prevention products, excluding condoms, provide no pregnancy protection. Intravaginal rings (IVRs) delivering antiretrovirals and contraceptives are a promising multipurpose prevention technology (MPT). Methods: Embedded within a Phase I randomized, placebo-controlled trial, we examined acceptability of continuous versus interrupted use of a 90-day MPT IVR among 47 low-risk women in Norfolk, Virginia and the Dominican Republic. A baseline survey assessed menstruation attitudes, risk perceptions and trial-related motivations. Follow-up surveys (M1/M3) examined user experiences with and preferences for IVR attributes; 18 women also participated in two in-depth interviews. Results: Most women rated the IVR's flexibility and smoothness (86%) and ease of insertion/removal (76%) as very acceptable. Fewer women similarly rated the IVR size (57%) and changes in color from menstruation (52%). Most participants experienced no changes or less bleeding. Those reporting more/heavier bleeding (20% M1, 15% M3) disliked the change. Overall, women preferred a 3-month (75%) to a 1-month IVR (7.5%) or a bimonthly injectable (10%). In qualitative interviews, women were willing to continuously use an IVR for 6-12 months, providing it did not "degrade" inside the body. Reasons for trial participation and prevention preferences, menstrual attitudes, and perceived IVR benefits and doubts varied by site. Conclusions: Findings provide strong evidence of demand for an MPT IVR that protects from pregnancy and HIV/STIs, lasts longer than 1 month, minimally disrupts menstrual bleeding, and is in women's control. numberClinicalTrials.gov: #NCT03279120.

Genital Mucosal Drug Concentrations and anti-HIV Activity in Tenofovir-Based PrEP Products: Intravaginal Ring vs. Oral Administration.

OBJECTIVE: To describe and compare systemic and local pharmacokinetics (PK) and cervicovaginal (CV) pharmacodynamics (PD) of oral tenofovir disoproxil fumarate (TDF) in combination with emtricitabine (FTC) with tenofovir (TFV) intravaginal ring (IVR). DESIGN: Phase I, randomized, parallel-group study. Women (n = 22) used TDF/FTC oral tablets daily or TFV IVR continuously and were assessed at baseline and 14 days. METHODS: TFV and FTC concentrations were measured in plasma, CV fluid (CVF), and CV tissue. TFV-diphosphate and FTC-triphosphate were assessed in CV tissue. In vitro PD antiviral activities of TFV and FTC (using in vivo concentration ranges) were modeled in the CVF and by infecting CV tissue explants ex vivo with HIV-1BaL. RESULTS: Adverse events (AEs) were more common with oral TDF/FTC use (P < 0.01). The median CVF TFV concentrations were 106 ng/mL after use of TFV IVR vs. 102 ng/mL for TDF/FTC. The median TFV and TFV-diphosphate concentrations in CV tissue were >100-fold higher among IVR users. The median CVF FTC concentrations were 103 ng/mL. FTC and FTC-triphosphate were detected in all CV tissues from TDF/FTC users. HIV inhibitory activity of CVF increased significantly with treatment in both cohorts (P < 0.01) but was higher in TFV IVR users (P < 0.01). In vitro inhibition of tissue infection with ex vivo administration of TFV and FTC was dose dependent, with maximal efficacy achieved with 10 µg/mL TFV, 1 µg/mL FTC, and 0.1 µg/mL of TFV and FTC combined. CONCLUSIONS: Both products were safe and increased mucosal HIV inhibitory activity. In addition to systemic protection, oral TDF/FTC displays a PK/PD profile compatible with CV mucosal antiviral activity. TFV IVR resulted in fewer AEs, lower TFV plasma concentrations, higher CVF and tissue TFV and TFV-DP concentrations, and greater anti-HIV activity in CVF.

Safety and Pharmacokinetics of a Tenofovir Alafenamide Fumarate-Emtricitabine based Oral Antiretroviral Regimen for Prevention of HIV Acquisition in Women: A Randomized Controlled Trial.

BACKGROUND: Daily oral emtricitabine (FTC, F)/tenofovir disoproxil fumarate (TDF) combination is approved for HIV pre-exposure prophylaxis (PrEP) in men and women. Tenofovir alafenamide fumarate (TAF) is a newer, more potent prodrug of tenofovir (TFV), and in combination with FTC, has recently been approved for prevention of HIV through rectal transmission. METHODS: This Phase I, prospective, interventional, randomized study was conducted in three clinical sites: PROFAMILIA, Santo Domingo, Dominican Republic; University of Pittsburgh and Eastern Virginia Medical School. We assessed the multi-compartmental pharmacokinetics (primary outcome) and safety (secondary outcome) among HIV uninfected women randomized to F/TDF (200mg/300mg) or F/TAF (200mg/25mg; F/TAF25) (n=24) in a single dose phase (SDP) and F/TDF, F/TAF (200mg/10mg; F/TAF10), or F/TAF25 (n=75) in a multiple dose (14 daily doses) phase (MDP). We described PK parameters in plasma, peripheral blood mononuclear cells (PBMCs), and cervicovaginal (CV) and rectal fluids and tissues. ClinicalTrials.gov #NCT02904369, completed. FINDINGS: Recruitment for the study began on 5 October 2016. The first participant was enrolled on 6 October 2016 and the last participant completed the study 21 November 2017. PLASMA: TFV concentrations area under curve (AUC) were ~20 fold lower following F/TAF versus F/TDF. TFV-diphosphate (TFV-DP) AUC concentrations in PBMCs were 7-fold higher with F/TAF25 versus F/TDF. Median TFV-DP concentrations in vaginal tissue (4hours post last dose) were approximately 6-fold higher with F/TAF25 versus F/TDF. TFV and TFV-DP were lower with F/TAF versus F/TDF in rectal tissue. Concentrations of FTC and FTC-triphosphate (FTC-TP) were similar across matrices and treatment arms. Gastrointestinal adverse events (AEs) occurred more frequently in F/TDF users (44.0%) than in either F/TAF group (11.5 and 12.0%). INTERPRETATION: F/TAF was safe and well-tolerated. TFV-DP concentrations were higher in PBMCs and similar or higher (4h post dose) in female genital tract tissues for F/TAF versus F/TDF. High FTC and FTC-TP concentrations in all compartments support the potential of F/TAF as a new PrEP combination for women.

Understanding Correlation Between CO2 Insertion Mechanism and Chain Length of Diamine in Metal-Organic Framework Adsorbents.

Although CO2 insertion is a predominant phenomenon in diamine-functionalized Mg2 (dobpdc) (dobpdc4- =4,4-dioxidobiphenyl-3,3'-dicarboxylate) adsorbents, a high-performance metal-organic framework for capturing CO2 , the fundamental function of the diamine carbon chain length in the mechanism remains unclear. Here, Mg2 (dobpdc) systems with open metal sites grafted by primary diamines NH2 -(CH2 )n -NH2 were developed, with en (n=2), pn (n=3), bn (n=4), pen (n=5), hn (n=6), and on (n=8). Based on CO2 adsorption and IR results, CO2 insertion is involved in frameworks with n=2 and 3 but not in systems with n≥5. According to NMR data, bn-appended Mg2 (dobpdc) exhibited three different chemical environments of carbamate units, attributed to different relative conformations of carbon chains upon CO2 insertion, as validated by first-principles density functional theory (DFT) calculations. For 1-hn and 1-on, DFT calculations indicated that diamine inter-coordinated open metal sites in adjacent chains bridged by carboxylates and phenoxides of dobpdc4- . Computed CO2 binding enthalpies for CO2 insertion (-27.8 kJ mol-1 for 1-hn and -20.2 kJ mol-1 for 1-on) were comparable to those for CO2 physisorption (-19.3 kJ mol-1 for 1-hn and -20.8 kJ mol-1 for 1-on). This suggests that CO2 insertion is likely to compete with CO2 physisorption on diamines of the framework when n≥5.

Emerging Porous Materials and Their Composites for NH3 Gas Removal.

NH3, essential for producing artificial fertilizers and several military and commercial products, is being produced at a large scale to satisfy increasing demands. The inevitable leakage of NH3 during its utilization, even in trace concentrations, poses significant environmental and health risks because of its highly toxic and reactive nature. Although numerous techniques have been developed for the removal of atmospheric NH3, conventional NH3 abatement systems possess the disadvantages of high maintenance cost, low selectivity, and emission of secondary wastes. In this context, highly tunable porous materials such as metal-organic frameworks, covalent organic frameworks, hydrogen organic frameworks, porous organic polymers, and their composite materials have emerged as next-generation NH3 adsorbents. Herein, recent progress in the development of porous NH3 adsorbents is summarized; furthermore, factors affecting NH3 capture are analyzed to provide a reasonable strategy for the design and synthesis of promising materials for NH3 abatement.

End-user preference for and choice of four vaginally delivered HIV prevention methods among young women in South Africa and Zimbabwe: the Quatro Clinical Crossover Study.

INTRODUCTION: Adherence to HIV prevention methods is a challenge, particularly for young women in Sub-Saharan Africa. End-user research during product development can inform modifiable factors to increase future uptake and adherence. METHODS: Preferences for four vaginally inserted placebo HIV prevention methods were assessed among Zimbabwean and South African young women using a crossover clinical design. For each of months 1 to 4, participants were asked to use a pre-coitally inserted film, insert (vaginal tablet) and gel once/week for a month, and a monthly ring in a randomly assigned sequence. Participants subsequently chose one preferred product to use as directed for the final study month. Women ranked the four products from most preferred to least preferred at enrolment and after trying all products. RESULTS: A total of 200 women aged 18 to 30 (mean 23) were enrolled; 178 (89%) completed follow-up. At baseline, 41% of participants selected the gel as their most preferred product and 61% selected the ring as least preferred. During the crossover period, most (82% to 85%) self-reported using each product at least once a week, although only half the time with sex. Objective biomarker data confirmed adequate use of all products. After trying each product, rankings changed with the film, ring, insert and gel being selected by 29%, 28%, 26% and 16% respectively. Choice varied significantly by country (p < 0.001): More Zimbabweans chose the film (45%), and more South Africans chose the insert (34%). Among women choosing the ring, 88% reported using it every time with sex. By contrast, self-reported adherence was lower for "on-demand" (coitally associated) products, with 40% to 55% using them every time during sex (p < 0.001). CONCLUSIONS: Preferences for these four dosage forms varied before and after use, and both within and across countries - there was no clear favourite - indicating the need for a range of options for end-users The ring's popularity increased the most with use, was the second most preferred delivery system, and per self-report, provided more coverage during sex. These end-user perspectives provide important information to product developers and funding agencies.

Development and clinical assessment of new objective adherence markers for four microbicide delivery systems used in HIV prevention studies.

BACKGROUND: Adherence is critical for successful topical, vaginally delivered anti-retroviral (ARV)-based HIV pre-exposure prophylaxis (PrEP). Quantitating systemic or tissue ARV levels through LC-MS/MS is currently viewed as the most reliable measure of adherence. However, for placebo-controlled trials, this is a high cost analysis that measures adherence only in the drug treatment group. A desirable marker of adherence is one that is measured in both placebo and drug treatment groups using a simple on-site clinical laboratory test, which allows necessary interventions for supporting participant adherence. Our objective was to develop adherence markers for four vaginal placebo products currently used as microbicide delivery systems: gel, film, insert, and intravaginal ring. Excipient and spectroscopy-based approaches were used for preclinical development of the placebo markers and subsequently validated by the CONRAD 135 study. The study collected vaginal swabs collected each day for 1 week post vaginal application of gel, film, or insert in the clinic with or without sex. Intravaginal rings were collected after 1 day, 7, and 30 days of use. RESULTS: Placebo gel, film, and insert in vaginal swabs were successfully detected by specific excipient colorimetric or probe-based assays for hydroxyethylcellulose, glycerin, and sorbitol respectively, as well as spectroscopy-based prediction models. The range of detection for gel, film, and insert in swabs collected up to 16 h post vaginal application was 70-100% of the total swabs per time point, with some markers showing potential for longer duration. Decreasing residual glycerin levels and increasing bioanalyte penetration of vaginally used intravaginal rings showed significant changes between 1 and 30 days of use. CONCLUSIONS: We demonstrated clinical proof-of-concept that adherence markers for placebo product can be measured using simple, lower cost approaches. Measuring adherence in both placebo and drug arms of a HIV PrEP study would better inform future trial designs.

"It Was Not My Aim to Sleep There": The Impact of Timing and Location of Sex on Adherence to Coitally-Dependent HIV Pre-exposure Prophylaxis.

The FACTS 001 trial found that vaginal pre- and post-coital application of 1% tenofovir gel did not prevent HIV-1 infection amongst young South African women. The trial included a multi-faceted approach to adherence support and collected objective and self-reported adherence measures. Using qualitative data collected from a random sub-set of FACTS 001 participants (135 in-depth interviews at product discontinuation and 13 focus group discussions at dissemination of trial results), we explore the importance of 'place' and 'timing' in shaping acts of sexual intimacy and product adherence. Demographically, this qualitative sub-sample is similar to the trial cohort of predominantly young, unemployed women living with parents or other family members. Sexual intimacy was largely unpredictable and happened across multiple locations in which women had limited privacy, autonomy, or control over the timing of sex. This made adherence to the dosing strategy challenging. Findings may inform the development of future event-driven pre-exposure prophylaxis regimens or products.