Environmental Impact of Polymer Fiber Manufacture

This review focuses on the effects on the environment due to the production of polymer-solvent solutions and the manufacture of polymeric fibers of thicknesses from a nanometer up to a millimeter using these solutions. The most common polymeric fiber manufacture methods are reviewed based on their effects on the environment, particularly from the use of hazardous materials and energy consumption. Published literature is utilized to analyze and quantify energy consumption of the manufacturing methods electrospinning, phase separation, self-assembly, template synthesis, drawing and pressurized gyration. The results show that during the manufacturing stage of the lifecycle of polymeric fibers, pressurized gyration is more environmentally efficient primarily due to its mass-producing features and fast processing of polymeric solutions into fibers, it also works best with water-based solutions. Further green alternatives are described such as the use of sustainable polymers and solvents to enhance the environmental benefit. Overall, it is shown that the most effective method of curbing the environmental impact of manufacturing polymeric fibers is the use of nontoxic, water-soluble polymers along with the evasion of toxic solvents

Soft, stiffness-controllable sensing tip for on-demand force range adjustment with angled force direction identification

Force sensors are essential for measuring and controlling robot-object interactions. However, current force sensors have limited usability in applications such as grasping and palpation, where the range of angled forces changes between tasks. To address this limitation this paper proposes a novel optical-based soft-tipped force sensor capable of adjusting its range and sensitivity through pneumatic modulation. This research describes the sensor’s design and examines the relationship between the internal pressure of the sensor and its sensing range, sensitivity, single-axis force-sensing accuracy, and capability of measuring the angle and magnitude of non-normal forces. Results indicate that by increasing the pressure in the sensor, the sensing range can be increased and the sensitivity decreased. These results demonstrate that the sensor can measure normal forces reliably at each pressure using 4th order fits with root-mean-square error (RMSE) ∈[0.032N0.110N] . Finally, it is also demonstrated that by using a neural network, the sensor can measure the angle and magnitude of non-normal forces with RMSEs on trained variables of 0.0120 Rad for Y-angle ( θY ) measurements, 0.0109 Rad for X-angle ( θX ) measurements, and 0.102 N for force measurements

Trends in Photopolymerizable Bioinks for 3D Bioprinting of Tumor Models

Three-dimensional (3D) bioprinting technologies involving photopolymerizable bioinks (PBs) have attracted enormous attention in recent times owing to their ability to recreate complex structures with high resolution, mechanical stability, and favorable printing conditions that are suited for encapsulating cells. 3D bioprinted tissue constructs involving PBs can offer better insights into the tumor microenvironment and offer platforms for drug screening to advance cancer research. These bioinks enable the incorporation of physiologically relevant cell densities, tissue-mimetic stiffness, and vascularized channels and biochemical gradients in the 3D tumor models, unlike conventional two-dimensional (2D) cultures or other 3D scaffold fabrication technologies. In this perspective, we present the emerging techniques of 3D bioprinting using PBs in the context of cancer research, with a specific focus on the efforts to recapitulate the complexity of the tumor microenvironment. We describe printing approaches and various PB formulations compatible with these techniques along with recent attempts to bioprint 3D tumor models for studying migration and metastasis, cell-cell interactions, cell-extracellular matrix interactions, and drug screening relevant to cancer. We discuss the limitations and identify unexplored opportunities in this field for clinical and commercial translation of these emerging technologies

3D direct-write printing of water soluble micromoulds for high-resolution rapid prototyping

Direct-write printing has contributed tremendously to additive manufacturing; in particular extrusion based printing where it has extended the range of materials for 3D printing and thus enabled use across many more sectors. The printing inks for direct-write printing however, need careful synthesis and invariably undergo extensive preparation before being able to print. Hence, new ink synthesis efforts are required every time a new material is to be printed; this is particularly challenging for low storage modulus (G’) materials like silicones, especially at higher resolutions (under 10 µm). Here we report the development of a precise (< 10 µm) 3D printable polymer, with which we 3D print micromoulds which are filled with standard silicones like polydimethylsiloxane (PDMS) and left to cure at room temperature. The proof of concept is demonstrated using a simple water soluble polymer as the mould material. The approach enables micrometre scale silicone structures to be prototyped with ease, away from the cleanroom

Casein fibres for wound healing

The name casein is given to a family of phosphoproteins which is commonly found in milk. Until recently, this was a constituent of milk that was commonly discarded; however today, it is widely used in health supplements all over the world. In this work, a high loading (50 wt%) of casein is mixed with a solution of polycaprolactone (PCL) to produce bandage-like fibres with an average fibre diameter of 1.4 ± 0.5 µm, which would be used to cover wounds in a series of tests with diabetic rats. Mouse fibroblast cell viability tests show that the casein-loaded fibres had little cytotoxicity with over 90% observed viability. A 14-day in vivo trial involving three groups of rats, used as control (no treatment), pure PCL fibres and casein-loaded fibres, showed that the casein within the fibres contributed to a significantly more extensive healing process. Histological analysis showed increased development of granulation tissue and follicle regrowth for the casein-loaded fibres. Further analysis showed that casein-loaded fibres have significantly lower levels of TNF-α, TGF-β IL-1β, NF-κB and IL-6, contributing to superior healing. The results presented here show an economical and simple approach to advanced wound healing

Pressure-Spun Fibrous Surgical Sutures for Localized Antibacterial Delivery: Development, Characterization, and In Vitro Evaluation

Surgical sutures designed to prevent infection are critical in addressing antibiotic-resistant pathogens that cause surgical site infections. Instead of antibiotics, alternative materials such as biocides have been assessed for coating commercially used sutures due to emerging antibiotic resistance concerns worldwide. This study has a new approach to the development of fibrous surgical sutures with the ability to deliver localized antibacterial agents. A new manufacturing process based on pressure spinning was used for the first time in the production of fibrous surgical sutures by physically blending antibacterial triclosan (Tri) agent with poly(lactic-co-glycolic acid) (PLGA) and poly(ethylene oxide) (PEO) polymers. Fibrous surgical sutures with virgin PLGA, virgin PEO, different ratios of PLGA-PEO, and different ratios of Tri-loaded PLGA-PEO fibrous sutures were produced to mimic the FDA- and NICE-approved PLGA-based sutures available in the market and compared for their characteristics. They were also tested simultaneously with commercially available sutures to compare their in vitro biodegradation, antibacterial, drug release, and cytotoxicity properties. After in vitro antibacterial testing for 24 h, sutures having 285 ± 12 μg/mg Tri loading were selected as a model for further testing as they exhibited antibacterial activity against all tested bacteria strains. The selected model of antibacterial fibrous sutures exhibited an initial burst of Tri release within 24 h, followed by a sustained release for the remaining time until the sutures completely degraded within 21 days. The cell viability assay showed that these surgical sutures had no cytotoxic effect on mammalian cells

Surface interactions and viability of coronaviruses

The recently emerged coronavirus pandemic (COVID-19) has become a worldwide threat affecting millions of people, causing respiratory system related problems that can end up with extremely serious consequences. As the infection rate rises significantly and this is followed by a dramatic increase in mortality, the whole world is struggling to accommodate change and is trying to adapt to new conditions. While a significant amount of effort is focused on developing a vaccine in order to make a game-changing anti-COVID-19 breakthrough, novel coronavirus (SARS-CoV-2) is also developing mutations rapidly as it transmits just like any other virus and there is always a substantial chance of the invented antibodies becoming ineffective as a function of time, thus failing to inhibit virus-to-cell binding efficiency as the spiked protein keeps evolving. Hence, controlling the transmission of the virus is crucial. Therefore, this review summarizes the viability of coronaviruses on inanimate surfaces under different conditions while addressing the current state of known chemical disinfectants for deactivation of the coronaviruses. The review attempts to bring together a wide spectrum of surface-virus-cleaning agent interactions to help identify material selection for inanimate surfaces that have frequent human contact and cleaning procedures for effective prevention of COVID-19 transmission.Peer reviewe

In vitro characterization of bionanocomposites with green silver nanoparticles: A step towards sustainable wound healing materials

This study investigated the characterization, antifungal activity, and biocompatibility of green agar/silver and collagen/silver bionanocomposite films for wound healing and cell growth scaffolds. Silver nanoparticles (AgNPs) are known for their antimicrobial properties, but their toxicity and harsh synthesis limit their applications. To address this, green‐synthesized AgNPs G‐AgNPs were incorporated into agar/collagen suspensions at specific concentrations and three different G‐AgNP‐agar and two different G‐AgNP‐col bionanocomposite films were produced. Nanoparticle homogeneity and film quality were characterized through SEM analysis. Mechanical properties were tested using a uniaxial tensile tester, revealing that the bioplastic control samples exhibited UTS of 3.86 MPa compared to 0.60 MPa for collagen, a 6‐fold improvement. Viable cell metabolic activity derived from MTT assay showed that Col‐4%AgNPs and Bio‐30%AgNPs had a 42.9% and 51.6% increase in net metabolic activity respectively compared to control on day 4. Fluorescence microscopy confirmed enhanced cell adhesion and proliferation in G‐AgNP‐incorporated samples. Antifungal properties were evaluated against Cladosporium spores, able to cause severe diseases when in contact with human skins, following ISO 16869:2008 standards. The demonstrated unique properties and tunability of G‐AgNPs bionanocomposites can be employed in a variety of specialties for wound‐healing applications, to improve rate and quality of healing while reducing the risk of infection

Scavenger Receptors and Their Potential as Therapeutic Targets in the Treatment of Cardiovascular Disease

Scavenger receptors act as membrane-bound and soluble proteins that bind to macromolecular complexes and pathogens. This diverse supergroup of proteins mediates binding to modified lipoprotein particles which regulate the initiation and progression of atherosclerotic plaques. In vascular tissues, scavenger receptors are implicated in regulating intracellular signaling, lipid accumulation, foam cell development, and cellular apoptosis or necrosis linked to the pathophysiology of atherosclerosis. One approach is using gene therapy to modulate scavenger receptor function in atherosclerosis. Ectopic expression of membrane-bound scavenger receptors using viral vectors can modify lipid profiles and reduce the incidence of atherosclerosis. Alternatively, expression of soluble scavenger receptors can also block plaque initiation and progression. Inhibition of scavenger receptor expression using a combined gene therapy and RNA interference strategy also holds promise for long-term therapy. Here we review our current understanding of the gene delivery by viral vectors to cells and tissues in gene therapy strategies and its application to the modulation of scavenger receptor function in atherosclerosis

Polymer–magnetic composite fibers for remote-controlled drug release

An efficient method is reported, for the fabrication of composite microfibers that can be magnetically actuated and are biocompatible, targeting controlled drug release. Aqueous solutions of polyvinyl alcohol, incorporated with citric acid-coated Fe₃O₄ magnetic nanoparticles (MNPs), are subject to infusion gyration to generate 100–300 nm diameter composite fibers, with controllable MNP loading. The fibers are stable in polar solvents, such as ethanol, and do not show any leaching of MNPs for over 4 weeks. Using acetaminophen as an example, we demonstrate that this material is effective in immobilization and triggered release of drugs, which is achieved by a moving external magnetic field. The remote actuation ability, coupled with biocompatibility and lightweight property, renders enormous potential for these fibers to be used as a smart drug release agent