Poly(Caprolactone)-Poly(N-Isopropyl Acrylamide)-Fe₃O₄ Magnetic Nanofibrous Structure with Stimuli Responsive Drug Release

Poly(caprolactone; PCL)—poly(N‐isopropylacrylamie; PNIPAAm)—Fe3O4 fiber, that can be magnetically actuated, is reported. Here, a structure is engineered that can be utilized as a smart carrier for the release of chemotherapeutic drug via magneto‐thermal activation, with the aid of magnetic nanoparticles (MNPs). The magnetic measurement of the fibers revealed saturation magnetization values within the range of 1.2–2.2 emu g−1. The magnetic PCL‐PNIPAAm‐Fe3O4 scaffold shows a specific loss power value of 4.19 W g−1 at 20 wt% MNPs. A temperature increase of 40 °C led to a 600% swelling after only 3 h. Doxorubicin (DOX) as a model drug, demonstrates a controllable drug release profile. 39% ± 0.92 of the total drug loaded is released after 96 h at 37 °C, while 25% drug release in 3 h at 40 °C is detected. Cytotoxicity results show no significant difference in cell attachment efficiency between the MNP‐loaded fibers and control while the DOX‐loaded fibers effectively inhibited cell proliferation at 24 h matching the drug release profile. The noncytotoxic effect, coupled with the magneto‐thermal property and controlled drug release, renders excellent potential for these fibers to be used as a smart drug‐release agent for localized cancer therapy

Direct metallisation of polyetherimide substrates by activation with different metals

This article reports the performance of different metallic ions and nanoparticles (Ag, Cu, Ni, Pd, Cr, Co, Au and Fe) used as seed layers, formed by chemical or optical reduction, for the electroless Cu plating of metal tracks onto polyetherimide (PEI). Plated Cu performance was tested by adhesion, electrical conductivity, plating rate, XPS, SEM, XRD and EDX analysis. The application of Cu and Ag seeds resulted in high quality electroless Cu deposits presenting strong adhesion properties and high conductivity ((2.0 ± 0.5) × 107 S/m and (3.6 ± 0.2) × 107 S/m, respectively) compared with bulk copper (5.96 × 107 S/m). Performance is attributed to the high surface density and uniformity of seed layers. Of the metals, only Ag ions were photoreduced under the conditions applied and were subsequently used to electroless Cu plate high quality track features of 150 μm width. The application of sulphuric acid pre-treatment to PEI prior to Ag ion exchange, improved the photoinitiated track formation process, as demonstrated by a threefold increase to both photoinduced Ag nanoparticle density on the surface and electroless Cu plating rate, as well as improved electroless Cu adhesion to PEI

A Rapid Photopatterning Method for Selective Plating of 2D and 3D Microcircuitry on Polyetherimide

In this work, a method for the rapid synthesis of metallic microtracks on polyetherimide is presented. The method relies on the photosynthesis of silver nanoparticles on the surface of the polymer substrates from photosensitive silver chloride (AgCl), which is synthesized directly on the polyetherimide surface. The study reveals that the use of AgCl as a photosensitive intermediate accelerates the reactions leading to the formation of silver nanoparticles by up to two orders of magnitude faster than other photodecomposition schemes. The patterning can be conducted under blue light, with notable advantages over UV exposure. Polymers of significant interest to the microelectronics and 3D printing industries can be directly patterned by light using this photography‐inspired technique at throughputs high enough to be commercially advantageous. Light exposures as short as a few seconds are sufficient to allow the direct metallization of the illuminated polyetherimide surface. The results show that the silver required for the seed layer is minimal, and the later copper electroless plating results in the selective growth of conductive tracks for circuitry on the light‐patterned areas, both on flexible films and 3D printed surfaces

Obesity-Related Oxidative Stress: the Impact of Physical Activity and Diet Manipulation

Obesity-related oxidative stress, the imbalance between pro-oxidants and antioxidants (e.g., nitric oxide), has been linked to metabolic and cardiovascular disease, including endothelial dysfunction and atherosclerosis. Reactive oxygen species (ROS) are essential for physiological functions including gene expression, cellular growth, infection defense, and modulating endothelial function. However, elevated ROS and/or diminished antioxidant capacity leading to oxidative stress can lead to dysfunction. Physical activity also results in an acute state of oxidative stress. However, it is likely that chronic physical activity provides a stimulus for favorable oxidative adaptations and enhanced physiological performance and physical health, although distinct responses between aerobic and anaerobic activities warrant further investigation. Studies support the benefits of dietary modification as well as exercise interventions in alleviating oxidative stress susceptibility. Since obese individuals tend to demonstrate elevated markers of oxidative stress, the implications for this population are significant. Therefore, in this review our aim is to discuss (i) the role of oxidative stress and inflammation as associated with obesity-related diseases, (ii) the potential concerns and benefits of exercise-mediated oxidative stress, and (iii) the advantageous role of dietary modification, including acute or chronic caloric restriction and vitamin D supplementation

Muscle Interstitial Cells: A Brief Field Guide to Non-satellite Cell Populations in Skeletal Muscle

Skeletal muscle regeneration is mainly enabled by a population of adult stem cells known as satellite cells. Satellite cells have been shown to be indispensable for adult skeletal muscle repair and regeneration. In the last two decades, other stem/progenitor cell populations resident in the skeletal muscle interstitium have been identified as "collaborators" of satellite cells during regeneration. They also appear to have a key role in replacing skeletal muscle with adipose, fibrous, or bone tissue in pathological conditions. Here, we review the role and known functions of these different interstitial skeletal muscle cell types and discuss their role in skeletal muscle tissue homeostasis, regeneration, and disease, including their therapeutic potential for cell transplantation protocols

A New Digitally Driven Process for the Fabrication of Integrated Flex-Rigid Electronics

Conventionally, flexible and rigid electronics are produced separately using mask-based lithography techniques thus requiring connectors to join circuits together introducing potential failure modes and additional assembly. This work demonstrates a new manufacturing approach which overcomes this limitation by allowing the co-fabrication of both flex and rigid electronic circuitry within the same part. This is achieved by hybridizing polyetherimide fused filament fabrication with selective photosynthesis of silver nanoparticles and copper electroless plating. The performance and reliability of this approach has been experimentally validated via manufacturing and testing positional sensors. By printing thin layers (< 50 µm), polyetherimide exhibits a high flexibility with minimal degradation from fatigue. Where part thicknesses exceed 180 µm, components start to exhibit rigid properties. A combination of various layer thicknesses allows rigid-flex substrates to be produced, with secondary processing to deposit the circuitry. Positional sensors with metalized feature sizes down to 300 µm have been fabricated that when deflected demonstrate a repeatable 1.4 Ω resistance change for 43,500 cycles

Spinach-based photo-catalyst for selective plating on polyimide-based substrates for micro-patterning circuitry

This work demonstrates the suitability of spinach extract as a bio-catalyser for the photo-catalysed synthesis of silver nanoparticles on polyimide and polyetherimide, and their suitability as a seed-layer for the formation of conductive micro-track after plating. The study reveals that the extract can accelerate the reaction rates of the photo-patterning process by an order of magnitude, when applied on materials for flexible electronics and 3D printing. The two main components of the extract that can act as photo-catalysers - chlorophylls and plasmatic salts - have been individually studied by energy-dispersive X-rays, UV/Vis spectroscopy and X-ray Diffraction. A simple and well-defined method for extraction of chlorophyll-A (Ch-A) from fresh spinach at 120 ± 20 mg/L, has been developed. The study reveals that the main component enhancing photoreduction rates is due to the ionic salts present in the extract. The spinach extract has been demonstrated to be a valid catalyser to achieve highly conductive, selective electroless copper plating of track features, of thickness 0.5 ± 0.2 μm and conductivity (0.7 ± 0.2) × 107 S/m. 10 μm wide tracks are obtained, and the copper plating withstands the adhesion test. Demonstration of selective, ionic-liquid immersion plating of silver onto electroless copper, highlights a high quality metal protective layer finishing process desirable for reduced waste and toxicity