Sources of polychlorinated dibenzo-p-dioxins and -furans to sediment in the Newtown Creek Superfund Site.

Polychlorinated dibenzo-p-dioxins and -furans (PCDD/Fs) are contaminants of concern in the New York/New Jersey Harbor and in the organisms of the Newtown Creek Superfund site, which lies within the harbor. Because PCDD/Fs are never intentionally produced, identifying their sources can be challenging. In this work, sources of PCDD/Fs to the sediment of Newtown Creek were investigated using Positive Matrix Factorization (PMF) to analyze two data sets containing data on concentrations of (1) PCDD/Fs and (2) PCDD/Fs plus polychlorinated biphenyls (PCBs).

Bio-orthogonal tuning of matrix properties during 3D cell culture to induce morphological and phenotypic changes.

Described herein is a protocol for producing a synthetic extracellular matrix that can be modified in situ during three-dimensional cell culture. The hydrogel platform is established using modular building blocks employing bio-orthogonal tetrazine (Tz) ligation with slow (norbornene, Nb) and fast (trans-cyclooctene, TCO) dienophiles. A cell-laden gel construct is created via the slow, off-stoichiometric Tz/Nb reaction.

Source apportionment of polychlorinated biphenyls in the sediment of the Newtown Creek superfund site.

Polychlorinated biphenyls (PCBs) are a primary contaminant of potential concern at the Newtown Creek superfund site. Measurements of PCBs in hundreds of samples of sediment (surface and cores) within Newtown Creek and at nearby reference locations were obtained from the Remedial Investigation (RI) databases. This data set was analyzed using Positive Matrix Factorization (PMF).

Enzymatic digestion does not compromise sliding-mediated cartilage lubrication.

Articular cartilage's remarkable low-friction properties are essential to joint function. In osteoarthritis (OA), cartilage degeneration (e.g.

Exogenous Collagen Crosslinking is Highly Detrimental to Articular Cartilage Lubrication.

Healthy articular cartilage is a remarkable bearing material optimized for near-frictionless joint articulation. Because its limited self-repair capacity renders it susceptible to osteoarthritis (OA), approaches to reinforce or rebuild degenerative cartilage are of significant interest. While exogenous collagen crosslinking (CXL) treatments improve cartilage's mechanical properties and increase its resistance to enzymatic degradation, their effects on cartilage lubrication remain less clear.

Cell therapy biomanufacturing: integrating biomaterial and flow-based membrane technologies for production of engineered T-cells.

Adoptive T-cell therapies (ATCTs) are increasingly important for the treatment of cancer, where patient immune cells are engineered to target and eradicate diseased cells. The biomanufacturing of ATCTs involves a series of time-intensive, lab-scale steps, including isolation, activation, genetic modification, and expansion of a patient's T-cells prior to achieving a final product. Innovative modular technologies are needed to produce cell therapies at improved scale and enhanced efficacy.

Modeling the Maturation of the Vocal Fold Lamina Propria Using a Bioorthogonally Tunable Hydrogel Platform.

Toward the goal of establishing an engineered model of the vocal fold lamina propria (LP), mesenchymal stem cells (MSCs) are encapsulated in hyaluronic acid (HA)-based hydrogels employing tetrazine ligation with strained alkenes. To mimic matrix stiffening during LP maturation, diffusion-controlled interfacial bioorthogonal crosslinking is carried out on the soft cellular construct using HA modified with a ferocious dienophile, trans-cyclooctene (TCO). Cultures are maintained in MSC growth media for 14 days to afford a model of a newborn LP that is homogeneously soft (nLP), a homogeneously stiffened construct zero (sLP0) or 7 days (sLP7) post cell encapsulation, and a mature LP model (mLP) with a stiff top layer and a soft bottom layer.

Tunable Synthesis of Hydrogel Microfibers via Interfacial Tetrazine Ligation.

Crosslinked, degradable, and cell-adhesive hydrogel microfibers were synthesized via interfacial polymerization employing tetrazine ligation, an exceptionally fast bioorthogonal reaction between strained -cyclooctene (TCO) and -tetrazine (Tz). A hydrophobic TCO crosslinker and homo-difunctional poly(ethylene glycol) (PEG)-based macromers with the tetrazine group conjugated to PEG via a stable carbamate (PEG-Tz1) bond or a labile hydrazone (PEG-Tz2) linkage were synthesized. After laying an ethyl acetate solution of TCO over an aqueous solution of Tz macromers, mechanically robust microfibers were continuously pulled from the oil-water interface.

Comparative tribology II-Measurable biphasic tissue properties have predictable impacts on cartilage rehydration and lubricity.

Healthy articular cartilage supports load bearing and frictional properties unmatched among biological tissues and man-made bearing materials. Balancing fluid exudation and recovery under loaded and articulated conditions is essential to the tissue's biological and mechanical longevity. Our prior tribological investigations, which leveraged the convergent stationary contact area (cSCA) configuration, revealed that sliding alone can modulate cartilage interstitial fluid pressurization and the recovery and maintenance of lubrication under load through a mechanism termed 'tribological rehydration.

Articular Cartilage Friction, Strain, and Viability Under Physiological to Pathological Benchtop Sliding Conditions.

Unlabelled: , articular cartilage is exceptionally resistant to wear, damage, and dysfunction. However, replicating cartilage's phenomenal tribomechanics (i.e.

Cartilage rehydration: The sliding-induced hydrodynamic triggering mechanism.

Loading-induced cartilage exudation causes loss of fluid from the tissue, joint space thinning and, in a long term prospective, the insurgence of osteoarthritis. Fortunately, experiments show that joints recover interstitial fluid and thicken during articulation after static loading, thus reversing the exudation process. Here, we provide the first original theoretical explanation to this crucial phenomenon, by implementing a numerical model capable of accounting for the multiscale porous lubrication occurring in joints.

Comparative Tribology: Articulation-induced rehydration of cartilage across species.

Articular cartilage is a robust tissue that facilitates load distribution and wear-free articulation in diarthrodial joints. These biomechanical capabilities are fundamentally tied to tissue hydration, whereby high interstitial fluid pressures and fluid load support facilitate the maintenance of low tissue strains and frictions. Our recent studies of cartilage sliding biomechanics using the convergent stationary contact area (cSCA) configuration, first introduced by Dowson and colleagues, unexpectedly demonstrated that sliding alone can promote recovery of interstitial pressure and lubrication lost to static compression through a mechanism termed 'tribological rehydration.

Detrimental effects of long sedentary bouts on the biomechanical response of cartilage to sliding.

: Epidemiological evidence suggests, contrary to popular mythos, that increased exercise/joint activity does not place articular cartilage at increased risk of disease, but instead promotes joint health. One explanation for this might be activity-induced cartilage rehydration; where joint articulation drives restoration of tissue hydration, thickness, and dependent tribomechanical outcomes (e.g.

Effects of mechanical injury on the tribological rehydration and lubrication of articular cartilage.

Healthy articular cartilage is crucial to joint function, as it provides the low friction and load bearing surface necessary for joint articulation. Nonetheless, joint injury places patients at increased risk of experiencing both accelerated cartilage degeneration and wear, and joint dysfunction due to post-traumatic osteoarthritis (PTOA). In this study, we used our ex vivo convergent stationary contact area (cSCA) explant testing configuration to demonstrate that high-speed sliding of healthy tissues against glass could drive consistent and reproducible recovery of compression-induced cartilage deformation, through the mechanism of 'tribological rehydration'.

Durability of Poly(3,4-ethylenedioxythiophene) (PEDOT) films on metallic substrates for bioelectronics and the dominant role of relative shear strength.

Despite growing interest in the use of conducting polymer coatings such as poly(3,4-ethylenedioxythiophene) (PEDOT) in bioelectronics, their relatively poor mechanical durability on inorganic substrates has limited long-term and clinical applications. Efforts to enhance durability have been limited by the lack of quantifiable metrics that can be used to evaluate the polymer film integrity and associated device failure. Here we examine the hypothesis that film failure under the tribological and cyclic electrical stressing becomes substantially less likely when the interfacial shear strength (τ) exceeds the shear strength of the film (τ).

Spatial Patterning of Molecular Cues and Vascular Cells in Fully Integrated Hydrogel Channels via Interfacial Bioorthogonal Cross-Linking.

Fully integrated hydrogel channels were fabricated via interfacial bioorthogonal cross-linking, a diffusion-controlled method for the creation and patterning of synthetic matrices based on the rapid bioorthogonal reaction between s-tetrazines (Tz) and trans-cyclooctene (TCO) dienophiles. Injecting an aqueous solution of a bisTCO cross-linker into a reservoir of tetrazine-modified hyaluronic acid (HA-Tz), while simultaneously drawing the syringe needle through the reservoir, yielded a cross-linked hydrogel channel that was mechanically robust. Fluorescent tags and biochemical signals were spatially patterned into the channel wall through time-dependent perfusion of TCO-conjugated molecules into the lumen of the channel.

Quantification of solute diffusivity in osteoarthritic human femoral cartilage using correlation spectroscopy.

Osteoarthritis is a chronic joint disease characterized by articular cartilage degeneration, pain, and disability. As an avascular tissue, the movement of water and solutes through the tissue is critical to cartilage health and function, and early changes in solute diffusivity due to micro-scale changes in the properties of cartilage's extracellular matrix might precede clinical symptoms. A diagnostic technique for quantifying alteration to the diffusive environment of cartilage that precedes macroscopic changes may allow for the earlier identification of osteoarthritic disease, facilitating earlier intervention strategies.

Cellular interactions with hydrogel microfibers synthesized via interfacial tetrazine ligation.

Fibrous proteins found in the natural extracellular matrix (ECM) function as host substrates for migration and growth of endogenous cells during wound healing and tissue repair processes. Although various fibrous scaffolds have been developed to recapitulate the microstructures of the native ECM, facile synthesis of hydrogel microfibers that are mechanically robust and biologically active have been elusive. Described herein is the use of interfacial bioorthogonal polymerization to create hydrogel-based microfibrous scaffolds via tetrazine ligation.

Mapping the spatiotemporal evolution of solute transport in articular cartilage explants reveals how cartilage recovers fluid within the contact area during sliding.

The interstitial fluid within articular cartilage shields the matrix from mechanical stresses, reduces friction and wear, enables biochemical processes, and transports solutes into and out of the avascular extracellular matrix. The balanced competition between fluid exudation and recovery under load is thus critical to the mechanical and biological functions of the tissue. We recently discovered that sliding alone can induce rapid solute transport into buried cartilage contact areas via a phenomenon termed tribological rehydration.

Unexpected Tribological Synergy in Polymer Blend Coatings: Leveraging Phase Separation to Isolate Domain Size Effects and Reduce Friction.

We employed a systematic processing approach to control phase separation in polymer blend thin films and significantly reduce dynamic friction coefficients (μ)s. We leveraged this modulation of phase separation to generate composite surfaces with dynamic friction coefficients that were substantially lower than expected on the basis of simple mixing rules, and in several cases, these friction coefficients were lower than those of both pure components. Using a model polyisoprene [PI]/polystyrene [PS] composite system, a minimum μ was found in films with PS mass fractions between 0.

Roles of the Fibrous Superficial Zone in the Mechanical Behavior of TMJ Condylar Cartilage.

In temporomandibular joints (TMJs), the cartilage on the condylar head displays a unique ultrastructure with a dense layer of type I collagen in the superficial zone, different from hyaline cartilage in other joints. This study aims to elucidate the roles of this fibrous zone in the mechanical behaviors, particularly lubrication, of TMJ under physiological loading regimes. Mechanical tests on porcine condylar cartilage demonstrated that the superficial and middle-deep zones exhibit tension-compression nonlinearity.

Microfabricated gas chromatograph for on-site determinations of TCE in indoor air arising from vapor intrusion. 2. Spatial/temporal monitoring.

We demonstrate the use of two prototype Si-microfabricated gas chromatographs (μGC) for continuous, short-term measurements of indoor trichloroethylene (TCE) vapor concentrations related to the investigation of TCE vapor intrusion (VI) in two houses. In the first house, with documented TCE VI, temporal variations in TCE air concentrations were monitored continuously for up to 48 h near the primary VI entry location under different levels of induced differential pressure (relative to the subslab). Concentrations ranged from 0.

Microfabricated gas chromatograph for on-site determination of trichloroethylene in indoor air arising from vapor intrusion. 1. Field evaluation.

Results are presented of inaugural field tests of two identical prototype microfabricated gas chromatographs (μGC) adapted for the in situ determination of trichloroethylene (TCE) in indoor air in support of vapor intrusion (VI) investigations. Each μGC prototype has a pretrap and partially selective high-volume sampler of conventional design, a micromachined-Si focuser for injection, dual micromachined-Si columns for separation, and an integrated array of four microscale chemiresistors with functionalized gold nanoparticle interface films for multichannel detection. Scrubbed ambient air is used as the carrier gas.

Functional characterization of normal and degraded bovine meniscus: rate-dependent indentation and friction studies.

The menisci are known to play important roles in normal joint function and the development of diseases such as osteoarthritis. However, our understanding of meniscus' load bearing and lubrication properties at the tissue level remains limited. The objective of this investigation was to characterize the site- and rate-dependency of the compressive and frictional responses of the meniscus under a spherical contact load.