Biofluid, Imaging, Physiological, and Functional Biomarkers of Mild Traumatic Brain Injury and Subconcussive Head Impacts.

Post-concussive symptoms are frequently reported by individuals who sustain mild traumatic brain injuries (mTBIs) and subconcussive head impacts, even when evidence of intracranial pathology is lacking. Current strategies used to evaluate head injuries, which primarily rely on self-report, have a limited ability to predict the incidence, severity, and duration of post-concussive symptoms that will develop in an individual patient. In addition, these self-report measures have little association with the underlying mechanisms of pathology that may contribute to persisting symptoms, impeding advancement in precision treatment for TBI. Emerging evidence suggests that biofluid, imaging, physiological, and functional biomarkers associated with mTBI and subconcussive head impacts may address these shortcomings by providing more objective measures of injury severity and underlying pathology. Interest in the use of biomarker data has rapidly accelerated, which is reflected by the recent efforts of organizations such as the National Institute of Neurological Disorders and Stroke and the National Academies of Sciences, Engineering, and Medicine to prioritize the collection of biomarker data during TBI characterization in acute-care settings. Thus, this review aims to describe recent progress in the identification and development of biomarkers of mTBI and subconcussive head impacts and to discuss important considerations for the implementation of these biomarkers in clinical practice.

Photoenhanced Degradation of Sarin at Cu/TiO2 Composite Aerogels: Roles of Bandgap Excitation and Surface Plasmon Excitation.

Multifunctional composites that couple high-capacity adsorbents with catalytic nanoparticles (NPs) offer a promising route toward the degradation of organophosphorus pollutants or chemical warfare agents (CWAs). We couple mesoporous TiO2 aerogels with plasmonic Cu nanoparticles (Cu/TiO2) and characterize the degradation of the organophosphorus CWA sarin under both dark and illuminated conditions. Cu/TiO2 aerogels combine high dark degradation rates, which are facilitated by hydrolytically active sites at the Cu||TiO2 interface, with photoenhanced degradation courtesy of semiconducting TiO2 and the surface plasmon resonance (SPR) of the Cu nanoparticles. The TiO2 aerogel provides a high surface area for sarin binding (155 m2 g-1), while the addition of Cu NPs increases the abundance of hydrolytically active OH sites. Degradation is accelerated on TiO2 and Cu/TiO2 aerogels with O2. Under broadband illumination, which excites the TiO2 bandgap and the Cu SPR, sarin degradation accelerates, and the products are more fully mineralized compared to those of the dark reaction. With O2 and broadband illumination, oxidation products are observed on the Cu/TiO2 aerogels as the hydrolysis products subsequently oxidize. In contrast, the photodegradation of sarin on TiO2 is limited by its slow initial hydrolysis, which limits the subsequent photooxidation. Accelerated hydrolysis occurs on Cu/TiO2 aerogels under visible illumination (>480 nm) that excites the Cu SPR but not the TiO2 bandgap, confirming that the Cu SPR excitation contributes to the broadband-driven activity. The high hydrolytic activity of the Cu/TiO2 aerogels combined with the photoactivity upon TiO2 bandgap excitation and Cu SPR excitation is a potent combination of hydrolysis and oxidation that enables the substantial chemical degradation of organophorphorus compounds.

Stabilization of reduced copper on ceria aerogels for CO oxidation.

Photodeposition of Cu nanoparticles on ceria (CeO2) aerogels generates a high surface area composite material with sufficient metallic Cu to exhibit an air-stable surface plasmon resonance. We show that balancing the surface area of the aerogel support with the Cu weight loading is a critical factor in retaining stable Cu0. At higher Cu weight loadings or with a lower support surface area, Cu aggregation is observed by scanning and transmission electron microscopy. Analysis of Cu/CeO2 using X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy finds a mixture of Cu2+, Cu+, and Cu0, with Cu+ at the surface. At 5 wt% Cu, Cu/CeO2 aerogels exhibit high activity for heterogeneous CO oxidation catalysis at low temperatures (94% conversion of CO at 150 °C), substantially out-performing Cu/TiO2 aerogel catalysts featuring the same weight loading of Cu on TiO2 (20% conversion of CO at 150 °C). The present study demonstrates an extension of our previous concept of stabilizing catalytic Cu nanoparticles in low oxidation states on reducing, high surface area aerogel supports. Changing the reducing power of the support modulates the catalytic activity of mixed-valent Cu nanoparticles and metal oxide support.

Semi-interpenetrating networks of hyaluronic acid in degradable PEG hydrogels for cartilage tissue engineering.

Hydrolytically biodegradable poly(ethylene glycol) (PEG) hydrogels offer a promising platform for chondrocyte encapsulation and tuning degradation for cartilage tissue engineering, but offer no bioactive cues to encapsulated cells. This study tests the hypothesis that a semi-interpenetrating network of entrapped hyaluronic acid (HA), a bioactive molecule that binds cell surface receptors on chondrocytes, and crosslinked degradable PEG improves matrix synthesis by encapsulated chondrocytes. Degradation was achieved by incorporating oligo (lactic acid) segments into the crosslinks. The effects of HA molecular weight (MW) (2.9×10(4) and 2×10(6)Da) and concentration (0.5 and 5mgg(-1)) were investigated. Bovine chondrocytes were encapsulated in semi-interpenetrating networks and cultured for 4weeks. A steady release of HA was observed over the course of the study with 90% released by 4weeks. Incorporation of HA led to significantly higher cell numbers throughout the culture period. After 8days, HA increased collagen content per cell, increased aggrecan-positive cells, while decreasing the deposition of hypertrophic collagen X, but these effects were not sustained long term. Measuring total sulfated glycosaminoglycan (sGAG) and collagen content within the constructs and released to the culture medium after 4weeks revealed that total matrix synthesis was elevated by high concentrations of HA, indicating that HA stimulated matrix production although this matrix was not retained within the hydrogels. Matrix-degrading enzymes were elevated in the low-, but not the high-MW HA. Overall, incorporating high-MW HA into degrading hydrogels increased chondrocyte number and sGAG and collagen production, warranting further investigations to improve retention of newly synthesized matrix molecules.