Selective hydrogen bonding controls temperature response of layer-by-layer upper critical solution temperature micellar assemblies.

This work establishes a correlation between the selectivity of hydrogen-bonding interactions and the functionality of micelle-containing layer-by-layer (LbL) assemblies. Specifically, we explore LbL films formed by assembly of poly(methacrylic acid) (PMAA) and upper critical solution temperature block copolymer micelles (UCSTMs) composed of poly(acrylamide-co-acrylonitrile) P(AAm-co-AN) cores and polyvinylpyrrolidone (PVP) coronae. UCSTMs had a hydrated diameter of ∼380 nm with a transition temperature between 45 and 50 °C, regardless of solution pH. Importantly, micelles were able to hydrogen-bond with PMAA, with the critical interaction pH being temperature dependent. To better understand the thermodynamic nature of these interactions, in depth studies using isothermal titration calorimetry (ITC) were conducted. ITC reveals opposite signs of enthalpies for binding of PMAA with micellar coronae vs. with the cores. Moreover, ITC indicates that pH directs the interactions of PMAA with micelles, selectively enabling binding with the micellar corona at pH 4 or with both the corona and the core at pH 3. We then explore UCSTM/PMAA LbL assemblies and show that the two distinct modes of PMAA interaction with the micelles (i.e. whether or not PMAA binds with the core) had significant effects on the film composition, structure, and functionality. Consistent with PMAA hydrogen bonding with the P(AAm-co-AN) micellar cores, a significantly higher fraction of PMAA was found within the films assembled at pH 3 compared to pH 4 by both spectroscopic ellipsometry and neutron reflectometry. Selective interaction of PMAA with PVP coronae of the assembled micelles, achieved by the emergence of partial ionization of PMAA at pH 4 was critical for preserving film functionality demonstrated as temperature-controlled swelling and release of a model small molecule, pyrene. The work done here can be applied to a multitude of assembled polymer systems in order to predict suppression/retention of their stimuli-responsive behavior.

Polyphosphazenes enable durable, hemocompatible, highly efficient antibacterial coatings.

Biocompatible antibacterial coatings are highly desirable to prevent bacterial colonization on a wide range of medical devices from hip implants to skin grafts. Traditional polyelectrolytes are unable to directly form coatings with cationic antibiotics at neutral pH and suffer from high degrees of antibiotic release upon exposure to physiological concentrations of salt. Here, novel inorganic-organic hybrid polymer coatings based on direct layer-by-layer assembly of anionic polyphosphazenes (PPzs) of various degrees of fluorination with cationic antibiotics (polymyxin B, colistin, gentamicin, and neomycin) are reported. The coatings displayed low levels of antibiotic release upon exposure to salt and pH-triggered response of controlled doses of antibiotics. Importantly, coatings remained highly surface active against Escherichia coli and Staphylococcus aureus, even after 30 days of pre-exposure to physiological conditions (bacteria-free) or after repeated bacterial challenge. Moreover, coatings displayed low (<1%) hemolytic activity for both rabbit and porcine blood. Coatings deposited on either hard (Si wafers) or soft (electrospun fiber matrices) materials were non-toxic towards fibroblasts (NIH/3T3) and displayed controllable fibroblast adhesion via PPz fluorination degree. Finally, coatings showed excellent antibacterial activity in ex vivo pig skin studies. Taken together, these results suggest a new avenue to form highly tunable, biocompatible polymer coatings for medical device surfaces.

Recovery From Opioid Use Disorder (OUD) After Monthly Long-acting Buprenorphine Treatment: 12-Month Longitudinal Outcomes From RECOVER, an Observational Study.

OBJECTIVES: While evidence has mounted regarding the short-term effectiveness of pharmacotherapy for opioid use disorder (OUD), little is known about longer-term psychosocial, economic, and health outcomes. We report herein 12-month outcomes for an observational study enrolling participants who had previously taken part in a long-acting buprenorphine subcutaneous injection (BUP-XR) trial for moderate to severe OUD. METHODS: The RECOVER (Remission from Chronic Opioid Use: Studying Environmental and SocioEconomic Factors on Recovery; NCT03604861) study enrolled participants from 35 US community-based sites. Self-reported sustained opioid abstinence over 12 months and self-reported past-week abstinence at 3-, 6-, 9-, and 12-month visits were assessed. Multiple regression models assessed the association of BUP-XR duration with abstinence, controlling for potential confounders. Withdrawal, pain, health-related quality of life, depression, and employment at RECOVER baseline and 12-month visits were also compared to values collected before treatment in the BUP-XR trial. RESULTS: Of 533 RECOVER participants, 425 completed the 12-month visit (average age 42 years; 66% male); 50.8% self-reported sustained 12-month and 68.0% past-week opioid abstinence. In multiple regressions, participants receiving 12-month versus ≤2-month BUP-XR treatment duration had significantly higher likelihood of sustained opioid abstinence (75.3% vs 24.1%; P = 0.001), with similar results for past-week self-reported abstinence over time. During RECOVER, participants had fewer withdrawal symptoms, lower pain, positive health-related quality of life, minimal depression, and higher employment versus pre-trial visit. CONCLUSIONS: RECOVER participants reported positive outcomes over the 12-month observational period, including high opioid abstinence and stable or improved humanistic outcomes. These findings provide insights into the long-term impact of pharmacotherapy in OUD recovery.

New Family of Water-Soluble Sulfo-Fluoro Polyphosphazenes and Their Assembly within Hemocompatible Nanocoatings.

In this work, novel sulfo-fluoro polyphosphazenes (PPzs) were synthesized via macromolecular substitution of polydichlorophosphazene utilizing "non-covalent protection" methodology by converting acid functionalities into hydrophobic alkylammonium salts. Resulting PPzs showed excellent solubility in aqueous solutions over a broad pH range and contained ∼25% sulfo- groups and 20% either trifluoroethoxy- (FESP) or trifluoromethylphenoxy- (FPSP) side groups, as determined by NMR spectroscopy. Their polyelectrolyte behavior was evaluated by binding with an oppositely charged polyion, branched polyethylenimine (PEI), which resulted in the formation of interpolymer complexes as shown by dynamic light scattering (DLS). Contrary to a sulfonated, nonfluorinated PPz homopolymer (SP), fluorinated macromolecules effectively bound human serum albumin (HSA) as revealed by dynamic light scattering and asymmetric flow field flow fractionation (AF4) studies. Moreover, FESP and FPSP both displayed low hemolytic activity as evaluated in solution using porcine red blood cells. Using the layer-by-layer (LbL) technique, FESP and FPSP were assembled into nanocoatings with PEI. Both fluorinated and nonfluorinated sulfo PPzs showed linear growth with PEI because of strong ionic pairing between sulfo and amino groups. However, films of fluorinated PPzs displayed higher hydrophobicity, lower swelling, and improved stability in high ionic strength environment when compared to coatings formed by a sulfonated, nonfluorinated SP, or a carbon-chain polymer poly(styrene sulfonic acid). Hemocompatibility of FESP and FPSP nanofilms was demonstrated in vitro using whole rabbit blood hemolysis tests, which showed less than 1% hemolysis. Altogether, the present study introduces a new class of hemocompatible, sulfo-fluoropolymers that shows promise for life science applications.

Remission from chronic opioid use-Studying environmental and socio-economic factors on recovery (RECOVER): Study design and participant characteristics.

Few opioid use disorder (OUD) treatment studies measure meaningful life changes during long-term recovery, focusing instead on retention and abstinence. Here, we report on the design and participant characteristics of the RECOVER study, a study exploring life changes in persons with OUD for up to 24 months following participation in a Phase III trial evaluating buprenorphine extended-release monthly injection for subcutaneous use (known as RBP-6000 during development). This multisite, observational, cohort study tracks clinical, environmental, and socio-economic changes using self-administered assessments, urine drug screens (UDS), and public databases. Outcomes include demographics (e.g., patient characteristics, employment history, criminal history), lifetime and recent OUD drug use and treatment, and current health and resource use. Demographic and psychosocial characteristics are compared to a national, population-based study. RECOVER participants (N = 533) tend to be single, white, males aged 26 years or older. Mean age at first opioid use was 21.7 years; lifetime substance-related overdose was 24.2%. At first assessment, 334 (62.7%) participants reported past 7-day and 296 (55.5%) reported past 28-day opioid abstinence. Five hundred UDS were collected at the first assessment; buprenorphine (90.6%), marijuana (45.2%), and opiates (34.4%) were most commonly identified. Two hundred forty-nine (47.2%) participants reported full- or part-time employment. Participants were like a national sample with differences found for age, race/ethnicity, employment, education, and health-related quality of life. We hope that further research using this approach can provide data supporting the patient-centered development of OUD treatments and be adopted by substance use disorder studies to incorporate recovery-related, life-activity outcomes.

Functional Surfaces through Controlled Assemblies of Upper Critical Solution Temperature Block and Star Copolymers.

Endowing surfaces with multiple advanced functionalities, such as temperature-controlled swelling or the triggered release of functional small molecules, is attractive for a large variety of applications ranging from smart textiles to advanced biomedical applications. This Invited Feature Article summarizes recent advances in the development of upper critical solution temperature (UCST) behavior of copolymers in aqueous solutions and compares the fundamental differences between lower critical solution temperature (LCST) and UCST transitions. The effect of polymer chemistry and architecture on UCST transitions is discussed for block copolymer micelles (BCMs) and star polymers in solution and assembled at surfaces. The inclusion of such nanocontainers (i.e., BCMs and star polymers) in layer-by-layer (LbL) coatings and how to control their responsive behavior through deposition conditions and binding partners is explored. Finally, the inclusion and temperature-triggered release of functional small molecules is explored for nanocontainers in LbL coatings. Taken together, UCST nanocontainers containing LbL films are promising building blocks for the development of new generations of practical, functional surface coatings.

Emerging Topics and Innovative Methodologies in Cannabis Research.

Cannabis use is ascendant in our society, affecting the health of our citizens, our social norms and social structures, and our economies. This special issue brings together a diverse set of research manuscripts that push the borders of our understanding of burgeoning cannabis use and displays innovative methods developed to study these phenomena.

Micelle-Coated, Hierarchically Structured Nanofibers with Dual-Release Capability for Accelerated Wound Healing and Infection Control.

Tailoring nanofibrous matrices-a material with much promise for wound healing applications-to simultaneously mitigate bacterial colonization and stimulate wound closure of infected wounds is highly desirable. To that end, a dual-releasing, multiscale system of biodegradable electrospun nanofibers coated with biocompatible micellar nanocarriers is reported. For wound healing, transforming growth factor-ß1 is incorporated into polycaprolactone/collagen (PCL/Coll) nanofibers via electrospinning and the myofibroblastic differentiation of human dermal fibroblasts is locally stimulated. To prevent infection, biocompatible nanocarriers of polypeptide-based block copolymer micelles are deposited onto the surfaces of PCL/Coll nanofibers using tannic acid as a binding partner. Micelle-modified fibrous scaffolds are favorable for wound healing, not only supporting the attachment and spreading of fibroblasts comparable to those on noncoated nanofibers, but also significantly enhancing fibroblast migration. Micellar coatings can be loaded with gentamicin or clindamycin and exhibit antibacterial activity as measured by Petrifilm and zone of inhibition assays as well as time-dependent reduction of cellular counts of Staphylococcus aureus cultures. Moreover, delivery time of antibiotic dosage is tunable through the application of a novel modular approach. Altogether, this system holds great promise as an infection-mitigating, cell-stimulating, biodegradable skin graft for wound management and tissue engineering.

Biocompatible Nanocoatings of Fluorinated Polyphosphazenes through Aqueous Assembly.

Nonionic fluorinated polyphosphazenes, such as poly[bis(trifluoroethoxy)phosphazene] (PTFEP), display superb biocompatibility, yet their deposition to surfaces has been limited to solution casting from organic solvents or thermal molding. Herein, hydrophobic coatings of fluorinated polyphosphazenes are demonstrated through controlled deposition of ionic fluorinated polyphosphazenes (iFPs) from aqueous solutions using the layer-by-layer (LbL) technique. Specifically, the assemblies included poly[(carboxylatophenoxy)(trifluoroethoxy)phosphazenes] with varied content of fluorine atoms as iFPs (or poly[bis(carboxyphenoxy)phosphazene] (PCPP) as a control nonfluorinated polyphosphazene) and a variety of polycations. Hydrophobic interactions largely contributed to the formation of LbL films of iFPs with polycations, leading to linear growth and extremely low water uptake. Hydrophobicity-enhanced ionic pairing within iFP/BPEI assemblies gave rise to large-amplitude oscillations in surface wettability as a function of capping layer, which were the largest for the most fluorinated iFP, while control PCPP/polycation systems remained hydrophilic regardless of the film top layer. Neutron reflectometry (NR) studies indicated superior layering and persistence of such layering in salt solution for iFP/BPEI films as compared to control PCPP/polycation systems. Hydrophobicity of iFP-capped LbL coatings could be further enhanced by using a highly porous polyester surgical felt rather than planar substrates for film deposition. Importantly, iFP/polycation coatings displayed biocompatibility which was similar to or superior to that of solution-cast coatings of a clinically validated material (PTFEP), as demonstrated by the hemolysis of the whole blood and protein adsorption studies.

Self-defensive antibiotic-loaded layer-by-layer coatings: Imaging of localized bacterial acidification and pH-triggering of antibiotic release.

Self-defensive antibiotic-loaded coatings have shown promise in inhibiting growth of pathogenic bacteria adhering to biomaterial implants and devices, but direct proof that their antibacterial release is triggered by bacterially-induced acidification of the immediate environment under buffered conditions remained elusive. Here, we demonstrate that Staphylococcus aureus and Escherichia coli adhering to such coatings generate highly localized acidification, even in buffered conditions, to activate pH-triggered, self-defensive antibiotic release. To this end, we utilized chemically crosslinked layer-by-layer hydrogel coatings of poly(methacrylic acid) with a covalently attached pH-sensitive SNARF-1 fluorescent label for imaging, and unlabeled-antibiotic (gentamicin or polymyxin B) loaded coatings for antibacterial studies. Local acidification of the coatings induced by S. aureus and E. coli adhering to the coatings was demonstrated by confocal-laser-scanning-microscopy via wavelength-resolved imaging. pH-triggered antibiotic release under static, small volume conditions yielded high bacterial killing efficiencies for S. aureus and E. coli. Gentamicin-loaded films retained their antibacterial activity against S. aureus under fluid flow in buffered conditions. Antibacterial activity increased with the number of polymer layers in the films. Altogether, pH-triggered, self-defensive antibiotic-loaded coatings become activated by highly localized acidification in the immediate environment of an adhering bacterium, offering potential for clinical application with minimized side-effects. STATEMENT OF SIGNIFICANCE: Polymeric coatings were created that are able to uptake and selectively release antibiotics upon stimulus by adhering bacteria in order to understand the fundamental mechanisms behind pH-triggered antibiotic release as a potential way to prevent biomaterial-associated infections. Through fluorescent imaging studies, this work importantly shows that adhering bacteria produce highly localized pH changes even in buffer. Accordingly such coatings only demonstrate antibacterial activity by antibiotic release in the presence of adhering bacteria. This is clinically important, because ad libitum releasing antibiotic coatings usually show a burst release and have often lost their antibiotic content when bacteria adhere.

Emergency Department Visits Involving Misuse and Abuse of the Antipsychotic Quetiapine: Results from the Drug Abuse Warning Network (DAWN).

Case reports in medical literature suggest that the atypical antipsychotic quetiapine, a medication not previously considered to have abuse potential, is now being subject to misuse and abuse (MUA; ie, taken when not prescribed for them or used in a way other than instructed by their health professional). Here we present systematic, nationally representative data from the 2005 to 2011 Drug Abuse Warning Network (DAWN) for prevalence of emergency department (ED) visits among the U.S. general population involving quetiapine and related to MUA, suicide attempts, and adverse reactions. Nationally, quetiapine-related ED visits increased 90% between 2005 and 2011, from 35,581 ED visits to 67,497. DAWN data indicate that when used without medical supervision for recreational/self-medication purposes, quetiapine poses health risks for its users, especially among polydrug users and women. These findings suggest that the medical and public health communities should increase vigilance concerning this drug and its potential for MUA.

Cigar and smokeless tobacco use in the lesbian, gay, and bisexual population.

Large population-based studies of alternative tobacco use in the lesbian, gay, and bisexual (LGB) population are needed to more fully measure tobacco use outcomes. This descriptive study used standard measures of alternative tobacco use from two separate, statewide household-based studies to compare basic prevalence rates in the LGB population and the general population in California. A total of 1,950 adult lesbians, bisexual women, heterosexual women who have sex with women, gay men, bisexual men, and heterosexual men who have sex with men, all living in California, completed surveys between 2003 and 2004. From a general population-based sample (California Tobacco Survey, 2002), a total of 11,037 adult women and 9,488 men were used as comparisons. The prevalence rates for lifetime and current cigar smoking and smokeless tobacco use were lower for all LGB subpopulations compared with the general population.