An alternative silicone-based passive sampling device to derive organotin concentrations in the aqueous phase.

Organotin compounds (OTs) are well studied in various environmental compartments, with a critical focus on the water column as their primary entry point into aquatic ecosystems. In this context, a method for the analysis of organotin (OTs) in water using silicone rubber-based passive sampling was optimized, validated, and field-tested. Validation covered crucial parameters, including the limit of detection (LOD), limit of quantification (LOQ), accuracy, precision, linearity, and matrix effect. The method was shown to be robust (R2 ≥ 0.99), with recoveries between 70.2 and 114.6%, and precise (CV < 12.8%) (N = 3). LODCw and LOQCw were ≤15 and ≤ 48 pg Sn L-1, respectively, for TBT and TPhT. The matrix effect showed to be low (>-20% ME < 20%) for all OTs but TPhT (69.4%). The silicone rubber-water partition coefficients (Log Ksr,w) were estimated at 3.37 for MBT, 3.77 for DBT, 4.17 for TBT, 3.49 for MPhT, 3.83 for DPhT, and 4.22 for TPhT. During the field study carried out between October 2021 and February 2022 at the entrance of the Port of Santos navigation channel (Southeastern Brazil), sampling rates ranged between 4.1 and 4.6 L d-1, and the equilibrium was achieved for MBT, DBT, MPhT, and DPhT after ∼45 days of deployment. The freely dissolved concentrations varied between 134 and 165 pg Sn L-1 for TBT, 388 and 610 pg Sn L-1 for DBT, and 1114 and 1509 pg Sn L-1 for MBT, while MPhT, DPhT, and TPhT were below the limit of detection. Results pointed out that J-FLEX® rubber-based passive sampling is a suitable and reliable alternative method for the continuous monitoring of OTs in the water column.

Engineering superhydrophobicity: a survey of coating techniques for silicone-based oil-water separation membranes.

Oil spills in the ocean and the release of contaminated wastewater from industries cause significant harm to the ecosystem and water sources. To tackle this environmental problem, oil-water mixture separation has been the subject of extensive research over the past few decades. Improving oil absorbents is crucial in removing organic contaminants from wastewater produced by industrial activities. To this end, there is an increasing need for materials that can efficiently and flexibly recover oils from contaminated ocean waters, industrial wastewater, and other sources. Silicones are often used for this purpose because of their exceptional mechanical and thermal durability, as well as their low toxicity. The materials produced from silicones, such as foam, sponge, or substrate, exhibit excellent oil-absorbing properties (maximum oil absorption range, 23.2-77 g/g) and outstanding compression cycles. This article review highlights the advancements in the manufacturing of silicone-based products that have been extensively researched for oil-water separation. Understanding the interdependencies that determine the structure, performance, and manufacturing strategy is essential to producing selective oil absorbents with more commercial potential in the future. Recycling of silicones has also become increasingly important as a goal for the circular economy.

Silicone Bioadhesive with Shear-Stiffening Effect: Rate-Responsive Adhesion Behavior and Wound Dressing Application.

Stimuli-responsive adhesives with on-demand adhesion capabilities are highly advantageous for facilitating wound healing. However, the triggering conditions of stimuli-responsive adhesives are cumbersome, even though some of them are detrimental to the adhesive and adjacent natural tissues. Herein, a novel stimuli-responsive adhesive called shear-stiffening adhesive (SSA) has been created by constructing a poly(diborosiloxane)-based silicone network for the first time, and SSA exhibits a rate-responsive adhesion behavior. Furthermore, we introduced bactericidal factors (PVP-I) into SSA and applied it as a wound dressing to promote the healing of infected wounds. Impressively, the wound dressing not only has excellent biocompatibility and long-term antibacterial properties but also performs well in accelerating wound healing. Therefore, this study provides a new strategy for the synthesis of intelligent adhesives with force rate response, which simplifies the triggering conditions by the force rate. Thus, SSA has great potential to be applied in wound management as an intelligent bioadhesive with on-demand adhesion performance.

Antimicrobial Functionalization of Silicone-graft-poly(N-vinylimidazole) Catheters.

In this work, we present the modification of a medical-grade silicone catheter with the N-vinylimidazole monomer using the grafting-from method at room temperature and induced by gamma rays. The catheters were modified by varying the monomer concentration (20-100 vol%) and the irradiation dose (20-100 kGy). Unlike the pristine material, the grafted poly(N-vinylimidazole) chains provided the catheter with hydrophilicity and pH response. This change allowed for the functionalization of the catheters to endow it with antimicrobial features. Thus, the quaternization of amines with iodomethane and bromoethane was performed, as well as the immobilization of silver and ampicillin. The inhibitory capacity of these materials, functionalized with antimicrobial agents, was challenged against Escherichia coli and Staphylococcus aureus strains, showing variable results, where loaded ampicillin was amply better at eliminating bacteria.

Evaluation of rheological properties of soft lining materials with different composition under various temperatures.

PURPOSE: The aim of this in vitro study was to evaluate the changes the rheological properties of some soft lining materials, to compare the rheological properties and viscoelastic behaviour at different temperatures. MATERIALS AND METHODS: Five soft lining materials (acrylic and silicone based) were used. the storage modulus (G'), loss modulus (G"), tan delta (tan δ) and complex viscosity (η') were chosen and for each material, measurements were repeated at 23, 33 and 37  °C, using an oscillating rheometer. All data were statistically analyzed using the Mann Whitney U test, Kruskal Wallis test and Conover's Multiple Comparison test at the significance level of 0.05. RESULTS: Soft lining materials had different viscoelastic properties and most of the materials showed different rheological behavior at 23, 33 and 37  °C. At the end of the test (t¹5), at all the temperatures, Sofreliner Tough M had the highest storage modulus values while Visco Gel had the highest loss Tan delta values. CONCLUSIONS: There were significant changes in the rheological parameters of all the materials. Also temperature affected the initial rheological properties, and polymerization reaction of all the materials, depending on temperature increase. CLINICAL IMPLICATIONS: Temperature affected the initial rheological properties, and polymerization reaction of soft denture liner materials, and clinical inferences should be drawn from such studies conducted. It can be recommended to utilize viscoelastic acrylic-based temporary soft lining materials with lower storage modulus, higher tan delta value, and high viscosity in situations where pain complaint persists and tissue stress is extremely significant, provided that they are replaced often.

Development and application of a protocol for extractables profiling from central venous catheters in neonates.

Peripherally inserted central catheters (PICC-lines) used in neonatology are made of thermoplastic polyurethane (TPU) or silicone. These materials usually contain substances that may leach into drug vehicles or blood. In this extractables study, we determined the optimal extraction conditions using TPU films containing defined amounts of butylhydroxytoluene (BHT) and then applied them on unused and explanted PICC-lines. Maceration and sonication tests were carried out with hexane, acetone and water as the extraction solvents. The analyses were performed using gas and liquid chromatography coupled with mass spectrometry detectors, as well as inductive coupled plasma optical emission spectroscopy to detect a wide range of extractables. We selected a limited list of substances to be sought from the usual adjuvants and monomers, related to their carcinogenic, mutagenic or reprotoxic properties and/or existence in endocrine disruptors lists. The TPU-film experiments showed that acetone was slightly better than hexane, and maceration better than sonication. When applied to PICC-lines, the extraction methods were almost similar but acetone was clearly better than hexane for TPU. From the 48 peaks initially observed in GC-MS, we ended up with 37 peaks to follow in TPU PICC-lines, among which were those of BHT and 4,4'-Methylenebis(cyclohexyl isocyanate) isomers. For silicone PICC-lines, out of 41 peaks initially observed in GC-MS, we followed 20 peaks, most of them being identified as cyclosiloxanes. Barium was the main inorganic element extracted for both PICC-lines. For TPU PICC-lines, the inter-batch variability was higher than for intra-batch, but in silicone devices both were similar. When compared to new PICC-lines, explanted TPU PICC-lines extracted peaks had a lower area under the curve (AUC), while the AUCs of the peaks were higher for the majority of silicone PICC-lines extract compounds. No identified substances were detected above their toxicological threshold, but isocyanates and cyclosiloxanes toxicity was mostly studied for other exposition routes than intravenous. The methods defined in this study were efficient in producing extractable profiles from both PICC-lines.

Development of Nontargeted Workflow of Occupational Exposure by Infrared Ion Spectroscopy and Silicone Wristbands' Passive Sampling.

A new approach using orthogonal analytical techniques is developed for chemical identification. High resolution mass spectrometry and infrared ion spectroscopy are applied through a 5-level confidence paradigm to demonstrate the effectiveness of nontargeted workflow for the identification of hazardous organophosphates. Triphenyl phosphate is used as a surrogate organophosphate for occupational exposure, and silicone wristbands are used to represent personal samplers. Spectral data of a target compound is combined with spectral data of the sodium adduct and quantum chemical calculations to achieve a confirmed identification. Here, we demonstrate a nontargeted workflow that identifies organophosphate exposure and provides a mechanism for selecting validated methods for quantitative analyses.

Altered Foreign Body Response at the Posterior Surface Compared to the Anterior Surface of Human Silicone Breast Implants.

Soft implantable devices are crucial to optimizing form and function for many patients. However, periprosthetic capsule fibrosis is one of the major challenges limiting the use of implants. Currently, little is understood about how spatial and temporal factors influence capsule physiology and how the local capsule environment affects the implant structure. In this work, we analyzed breast implant capsule specimens with staining, immunohistochemistry, and real-time polymerase chain reaction to investigate spatiotemporal differences in inflammation and fibrosis. We demonstrated that in comparison to the anterior capsule against the convex surface of breast implants, the posterior capsule against the flat surface of the breast implant displays several features of a dysregulated foreign body reaction including increased capsule thickness, abnormal extracellular remodeling, and infiltration of macrophages. Furthermore, the expression of pro-inflammatory cytokines increased in the posterior capsule across the lifespan of the device, but not in the anterior capsule. We also analyzed the surface oxidation of breast explant samples with XPS analysis. No significant differences in surface oxidation were identified either spatially or temporally. Collectively, our results support spatiotemporal heterogeneity in inflammation and fibrosis within the breast implant capsule. These findings presented here provide a more detailed picture of the complexity of the foreign body reaction surrounding implants destined for human use and could lead to key research avenues and clinical applications to treat periprosthetic fibrosis and improve device longevity.

Safety Assessment of Polysilicone-11 as Used in Cosmetics.

The Expert Panel for Cosmetic Ingredient Safety (Panel) assessed the safety of Polysilicone-11 as used in cosmetic formulations. This ingredient is reported to function as a film former. The Panel considered the available data and concluded that Polysilicone-11 is safe in cosmetics in the present practices of use and concentration described in this safety assessment.

Investigating the anti-bioadhesion properties of short, medium chain length, and amphiphilic polyhydroxyalkanoate films.

Silicone materials are widely used in fouling release coatings, but developing eco-friendly protection via biosourced coatings, such as polyhydroxyalcanoates (PHA) presents a major challenge. Anti-bioadhesion properties of medium chain length PHA and short chain length PHA films are studied and compared with a reference Polydimethylsiloxane coating. The results highlight the best capability of the soft and low-roughness PHA-mcl films to resist bacteria or diatoms adsorption as compared to neat PDMS and PHBHV coatings. These parameters are insufficient to explain all the results and other properties related to PHA crystallinity are discussed. Moreover, the addition of a low amount of PEG copolymers within the coatings, to create amphiphilic coatings, boosts their anti-adhesive properties. This work reveals the importance of the physical or chemical ambiguity of surfaces in their anti-adhesive effectiveness and highlights the potential of PHA-mcl film to resist the primary adhesion of microorganisms.

Expanding the access of wearable silicone wristbands in community-engaged research through best practices in data analysis and integration.

Wearable silicone wristbands are a rapidly growing exposure assessment technology that offer researchers the ability to study previously inaccessible cohorts and have the potential to provide a more comprehensive picture of chemical exposure within diverse communities. However, there are no established best practices for analyzing the data within a study or across multiple studies, thereby limiting impact and access of these data for larger meta-analyses. We utilize data from three studies, from over 600 wristbands worn by participants in New York City and Eugene, Oregon, to present a first-of-its-kind manuscript detailing wristband data properties. We further discuss and provide concrete examples of key areas and considerations in common statistical modeling methods where best practices must be established to enable meta-analyses and integration of data from multiple studies. Finally, we detail important and challenging aspects of machine learning, meta-analysis, and data integration that researchers will face in order to extend beyond the limited scope of individual studies focused on specific populations.

Study of silicone hydrogel contact lenses' surface reflection characteristics using confocal microscopy.

The physical and chemical properties of contact lenses (CLs) differ significantly from one another. This is already covered by the FDA classification, which divides soft lenses into groups and subgroups for additional characteristics. The differences relate to both the interior and surface of the lens. Several differences in the surface characteristics of individual contact lenses have been studied and demonstrated to date. However, one of their fundamental physical properties, that is light reflection or, quantitatively, reflectance has not been compared. This paper describes the surface differences of a range of silicone-hydrogel (SiHy) lenses using reflectance confocal microscopy. It shows the relationship between the amount of light reflected from the lens surface and the material parameters. Common SiHy lens materials were used in the study, including two lenses with surface modifications. Light incident at the interface between two media (phosphate-buffered saline and lens) with different refractive indices is partially reflected. The normalized results show significant differences between the reflection signals (1 vs 0.07), and that they are not correlated with the refractive index (R2 = 0.5536). For the water content (%H2O), a general trend was observed that the higher the %H2O, the lower the reflection signal is (R2 = 0.8105). The reflection signal and surface modulus show the best correlation. (R2 = 0.9883). The proposed CLs analysis method, using reflectance confocal microscopy, provides data to differentiate between lenses with and without surface modifications.

Measuring semi-volatile organic compound exposures during pregnancy using silicone wristbands.

Silicone wristbands were utilized as personal passive samplers in a sub-cohort of 92 women, who participated in New York University Children's Health and Environment Study, to assess exposure to semi-volatile organic compounds (SVOCs). Wristbands were analyzed for 77 SVOCs, including halogenated and non-halogenated organophosphate esters (OPEs), polychlorinated biphenyls (PCBs), pesticides, phthalates, and brominated flame retardants (BFRs) (e.g. polybrominated diphenyl ethers (PBDEs)). This study aimed to look for patterns in chemical exposure utilizing participant demographics gathered from a questionnaire, and chemical exposure data across multiple timepoints during pregnancy. Analysis focused on 27 compounds detected in at least 80% of the wristbands examined. The chemicals detected most frequently included two pesticides, eight phthalates, one phthalate alternative, seven BFRs, and nine OPEs, including isopropylated and tert-butylated triarylphosphate esters (ITPs and TBPPs). Co-exposure to different SVOCs was most prominent in compounds that were within the same chemical class or were used in similar consumer applications such as phthalates and OPEs, which are often used as plasticizers. Pre-pregnancy BMI was positively associated with multiple compounds, and there were both positive and negative associations between women's parity and SVOC exposure. Outdoor temperature was not correlated with the wristband concentrations over a five-day sampling period. Lastly, significant and moderately high Intraclass Correlation Coefficient (ICC) (0.66-0.84) values for phthalate measurementsacross pregnancy indicate chronic exposure and suggest that using wristbands during one sampling period may reliably predict exposure. However, multiple sampling periods may be necessary to accurately determine indoor exposure to other SVOCs including OPEs and BFRs.

3D-printed biosurfactant-chitosan antibacterial coating for the prevention of silicone-based associated infections.

Infections associated with the surfaces of medical devices represent a critical problem due to biofilm formation and the growing resistance towards antibacterial drugs. This is particularly relevant in commonly used invasive devices such as silicone-based ones where a demand for alternative antibiofilm surfaces is increasing. In this work, an antimicrobial chitosan-biosurfactant hydrogel mesh was produced by 3D-printing. The 3D structure was designed to coat polydimethylsiloxane-based medical devices for infection prevention. Additionally, the porous 3D structure allows the incorporation of customized bioactive components. For this purpose, two biosurfactants (surfactin and sophorolipids) were biosynthesized and tested for their antimicrobial activity. In addition, the printing of surfactant-chitosan-based coatings was optimized, and the resulting 3D structures were characterized (i.e., wettability, FTIR-ATR, antimicrobial activity, and biocompatibility). Compared with surfactin, the results showed a better yield and higher antibacterial activity against Gram-positive bacteria for sophorolipids (SLs). Thus, SLs were used to produce chitosan-based 3D-printed coatings. Overall, the SLs-impregnated coatings showed the best antibacterial activity against Staphylococcus aureus planktonic bacteria (61 % of growth inhibition) and antibiofilm activity (2 log units reduction) when compared to control. Furthermore, concerning biocompatibility, the coatings were cytocompatible towards human dermal fibroblasts. Finally, the coating presented a mesh suitable to be filled with a model bioactive compound (i.e., hyaluronic acid), paving the way to be used for customized therapeutics.

Impact of autoclavation on baked-on siliconized containers for biologics.

Many pharmaceutical manufacturing units utilize pre-sterilized ready-to fill primary containers for parenterals. The containers may have been sterilized by the supplier via autoclavation. This process can change the physicochemical properties of the material and the subsequent product stability. We studied the impact of autoclavation on baked on siliconized glass containers for biopharmaceuticals. We characterized the container layers of different thickness before and after autoclavation for 15 min at 121 °C and 130 °C. Furthermore, we analyzed the adsorption of a mAb to the silicone layer and subjected filled containers to 12 weeks storage at 40 °C monitoring functionality and subvisible particle formation of the product. Autoclavation turned the initially homogenous silicone coating into an incoherent surface with uneven microstructure, changed surface roughness and energy, and increased protein adsorption. The effect was more pronounced at higher sterilization temperatures. We did not observe an effect of autoclavation on stability. Our results did not indicate any concerns for autoclavation at 121 °C for safety and stability of drug/device combination products using baked-on siliconized glass containers.

Do cats mirror their owner? Paired exposure assessment using silicone bands to measure residential PAH exposure.

It has been suggested that domestic animals can serve as sentinels for human exposures. In this study our objectives were to demonstrate that i) silicone collars can be used to measure environmental exposures of (domestic) animals, and that ii) domestic animals can be used as sentinels for human residential exposure. For this, we simultaneously measured polycyclic aromatic hydrocarbons (PAHs) using silicone bands worn by 30 pet cats (collar) and their owner (wristband). Collars and wristbands were worn for 7 days and analyzed via targeted Gas Chromatography-Mass Spectrometry (GC-MS). Demographics and daily routines were collected for humans and cats. Out of 16 PAHs, 9 were frequently detected (>50% of samples) in both wristbands and collars, of which Phenanthrene and Fluorene were detected in all samples. Concentrations of wristbands and collars were moderately correlated for these 9 PAHs (Median Spearman's r = 0.51 (range 0.16-0.68)). Determinants of PAH concentrations of cats and humans showed considerable overlap, with vacuum cleaning resulting in higher exposures and frequent changing of bed sheets in lower exposures. This study adds proof-of-principle data for the use of silicone collars to measure (domestic) animal exposure and shows that cats can be used as sentinels for human residential exposure.

Engineering and Development of a Tissue Model for the Evaluation of Microneedle Penetration Ability, Drug Diffusion, Photothermal Activity, and Ultrasound Imaging: A Promising Surrogate to Ex Vivo and In Vivo Tissues.

Driven by regulatory authorities and the ever-growing demands from industry, various artificial tissue models have been developed. Nevertheless, there is no model to date that is capable of mimicking the biomechanical properties of the skin whilst exhibiting the hydrophilicity/hydrophobicity properties of the skin layers. As a proof-of-concept study, tissue surrogates based on gel and silicone are fabricated for the evaluation of microneedle penetration, drug diffusion, photothermal activity, and ultrasound bioimaging. The silicone layer aims to imitate the stratum corneum while the gel layer aims to mimic the water-rich viable epidermis and dermis present in in vivo tissues. The diffusion of drugs across the tissue model is assessed, and the results reveal that the proposed tissue model shows similar behavior to a cancerous kidney. In place of typical in vitro aqueous solutions, this model can also be employed for evaluating the photoactivity of photothermal agents since the tissue model shows a similar heating profile to skin of mice when irradiated with near-infrared laser. In addition, the designed tissue model exhibits promising results for biomedical applications in optical coherence tomography and ultrasound imaging. Such a tissue model paves the way to reduce the use of animals testing in research whilst obviating ethical concerns.

Synthesis and characterization of UV curable biocompatible hydrophilic copolymers containing siloxane units.

Tissues are highly three-dimensional structure complexes composed of different cell types and their interactions. One of the main challenges in tissue engineering is the inability to produce large, highly perfused scaffolds in which cells can grow at a high cell density and viability. Poly(dimethyl siloxane) (PDMS) is used as a flexible, biocompatible cell culture substrate with tunable mechanical properties. However, its fragility and hydrophobicity still pose a challenge. Here, we present a new strategy for the three-step one-pot synthesis of novel biocompatible hydrophilic copolymers containing siloxane units. In the first step, free radical copolymerization of acrylic acid (AA), butyl methacrylate (BMA), and 2-hydroxyethyl methacrylate (HEMA) was carried out in dioxane (DO) solution in the presence of 2,2'-azodiisobutyronitrile (AIBN). In the second step, the copolymers were modified with diepoxypropoxypropyl-terminated polydimethylsiloxane (DE-PDMS), and in the third step, the copolymers were additionally modified with glycidyl methacrylate (GMA). The modified copolymers were characterized by FTIR, NMR spectroscopy and elemental analysis. Films of modified copolymers were prepared by UV curing. SEM studies revealed microphase separated morphology with distribution of PDMS domains. The mechanical properties of the films depended on the amount of incorporated silicone modifier. The films were more hydrophilic than PDMS films. All novel copolymers showed high biocompatibility.

PDMS networks meet barnacles: a complex and often toxic relationship.

The biological impact of chemical formulations used in various coating applications is essential in guiding the development of new materials that directly contact living organisms. To illustrate this point, an investigation addressing the impact of chemical compositions of polydimethylsiloxane networks on a common platform for foul-release biofouling management coatings was conducted. The acute toxicity of network components to barnacle larvae, the impacts of aqueous extracts of crosslinker, silicones and organometallic catalyst on trypsin enzymatic activity, and the impact of assembled networks on barnacle adhesion was evaluated. The outcomes of the study indicate that all components used in the formulation of the silicone network alter trypsin enzymatic activity and have a range of acute toxicity to barnacle larvae. Also, the adhesion strength of barnacles attached to PDMS networks correlates to the network formulation protocol. This information can be used to assess action mechanisms and risk-benefit analysis of PDMS networks.

Development and evaluation of a drug-in-adhesive transdermal delivery system for delivery of olanzapine.

OBJECTIVES: Olanzapine (OZP) is a safe and effective atypical antipsychotic drug used in treating schizophrenia and bipolar disorders. The dosage forms currently on the market for OZP are administered via oral or intramuscular routes. However, there are many problems associated with oral and intramuscular routes of drug administration. Thus, our aim was to develop a drug-in-adhesive transdermal delivery system (TDS) that can deliver OZP for 3 days. METHODS: We determined passive permeation, effect of oleic acid as chemical enhancer, and delivery of OZP across different skin types. Based on preliminary studies and saturation solubility of OZP in different pressure-sensitive adhesives (PSAs), we formulated and characterized solution-based TDS in acrylate PSA and suspension-based TDS in silicone and PIB PSA, with oleic acid as chemical enhancer. RESULTS: Acrylate solution-based TDS, silicone, and PIB suspension-based TDS delivered 58.97 ± 6.59 µg/sq.cm, 129.34 ± 16.59 µg/sq.cm, and 245.00 ± 2.51 µg/sq.cm, respectively, using in vitro permeation testing. PIB PSA suspension-based TDS met the 3 days desired target delivery. Skin irritation testing using In vitro EpiDermTM skin irritation test (EPI-200-SIT) kit found PIB TDS to be nonirritant. CONCLUSION: The PIB PSA suspension-based TDS could serve as a potentially effective transdermal delivery system for olanzapine.