3D Bioprinted Xanthan Hydrogels with Dual Antioxidant and Chondrogenic Functions for Post-traumatic Cartilage Regeneration.

Intra-articular trauma typically initiates the overgeneration of reactive oxidative species (ROS), leading to post-traumatic osteoarthritis and cartilage degeneration. Xanthan gum (XG), a branched polysaccharide, has shown its potential in many biomedical fields, but some of its inherent properties, including undesirable viscosity and poor mechanical stability, limit its application in 3D printed scaffolds for cartilage regeneration. In this project, we developed 3D bioprinted XG hydrogels by modifying XG with methacrylic (MA) groups for post-traumatic cartilage therapy. Our results demonstrated that the chemical modification optimized the viscoelasticity of the bioink, improved printability, and enhanced the mechanical properties of the resulting scaffolds. The XG hydrogels also exhibit decent ROS scavenging capacities to protect stem cells from oxidative stress. Furthermore, XGMA(H) (5% MA substitution) exhibited superior chondrogenic potential in vitro and promoted cartilage regeneration in vivo. These dual-functional XGMA hydrogels may provide a new opportunity for cartilage tissue engineering.

Nanochitin for sustainable and advanced manufacturing.

Presently, the rapid depletion of resources and drastic climate change highlight the importance of sustainable development. In this case, nanochitin derived from chitin, the second most abundant renewable polymer in the world, possesses numerous advantages, including toughness, easy processability and biodegradability. Furthermore, it exhibits better dispersibility in various solvents and higher reactivity than chitin owing to its increased surface area to volume ratio. Additionally, it is the only natural polysaccharide that contains nitrogen. Therefore, it is valuable to further develop this innovative technology. This review summarizes the recent developments in nanochitin and specifically identifies sustainable strategies for its preparation. Additionally, the different biomass sources that can be exploited for the extraction of nanochitin are highlighted. More importantly, the life cycle assessment of nanochitin preparation is discussed, followed by its applications in advanced manufacturing and perspectives on the valorization of chitin waste.

Green Nanocellulose/PEI-Grafted Magnetic Nanoparticles for Effective Removal of Heavy Metal Ions.

In response to the pressing issue of water pollution caused by heavy metal ions, there is a growing demand for green adsorbents that can effectively remove these contaminants while being easy to separate and regenerate. A novel magnetic composite was synthesized by bonding amino-functionalized Fe3 O4 -SiO2 magnetic particles (MNP-NH2 ) to polyethyleneimine (PEI)-grafted cellulose nanofibers (CNF). The modification of CNF with PEI through a peptidic coupling reaction resulted in the uniform dispersion and strong attachment of MNP-NH2 particles (286.7 nm) onto the PEI-CNF surface. This composite exhibited exceptional adsorption capabilities for heavy metals, achieving 16.73 mg/g for Pb, 16.12 mg/g for Cu, and 12.53 mg/g for Co. These remarkable adsorption capacities are attributed to the complex interactions between the metal ions and the amino, carboxyl, and hydroxyl groups on the surface of PEI-CNF-MNP. The introduction of PEI significantly enhanced the adsorption capacities, and the adsorption sequence (Pb(II)>Cu(II)>Co(II)) can be explained by differences in ionic radius and surface complexation strength. Langmuir isotherm and pseudo-second-order kinetic models described the adsorption process, while Na2 EDTA was proved effective for desorption with high recovery rates. This magnetic composite holds promise for treating heavy metal-contaminated wastewater due to its impressive performance.

Synergistic antibacterial action of lignin-squaraine hybrid photodynamic therapy: advancing towards effective treatment of antibiotic-resistant bacteria.

Antibacterial photodynamic therapy (aPDT) is emerging as an effective means of treating pathogenic bacteria, especially in light of the challenges posed by antibiotic resistance. SQR29, an organophotosensitizer, was encapsulated in a poly(lignin/PEG/PPG urethane) hydrogel to enable targeted treatment at a specific infected area. The hydrogel exhibited free radical scavenging properties which were effective in preventing oxidative stress and promoted wound healing. The hydrogel exhibited a significant aPDT effect on Gram-positive bacteria, hence showing its potential in combating antibiotic-resistant pathogenic bacteria in chronic wound infection.

In-situ forming dynamic covalently crosslinked nanofibers with one-pot closed-loop recyclability.

Polymeric nanofibers are attractive nanomaterials owing to their high surface-area-to-volume ratio and superior flexibility. However, a difficult choice between durability and recyclability continues to hamper efforts to design new polymeric nanofibers. Herein, we integrate the concept of covalent adaptable networks (CANs) to produce a class of nanofibers ⎯ referred to dynamic covalently crosslinked nanofibers (DCCNFs) via electrospinning systems with viscosity modulation and in-situ crosslinking. The developed DCCNFs possess homogeneous morphology, flexibility, mechanical robustness, and creep resistance, as well as good thermal and solvent stability. Moreover, to solve the inevitable issues of performance degradation and crack of nanofibrous membranes, DCCNF membranes can be one-pot closed-loop recycled or welded through thermal-reversible Diels-Alder reaction. This study may unlock strategies to fabricate the next generation nanofibers with recyclable features and consistently high performance via dynamic covalent chemistry for intelligent and sustainable applications.

Nano-Strategies for Lignin Biomaterials toward Cancer Therapy.

Lignin is a nontoxic and biocompatible biopolymer with many promising characteristics, including a high tensile strength and antioxidant properties. This natural polymer can be processed through several chemical methods and modified into lignin nanomaterials for potential biomedical applications. This review summarizes the latest developments in nanolignin (NL)-based biomaterials for cancer therapy; various NL applications related to cancer therapy are considered, including drug and gene delivery, biosensing, bioimaging, and tissue engineering. The manuscript also outlines the potential use of these materials to improve the therapeutic potency of chemotherapeutic drugs by decreasing their dose and reducing their adverse effects. Due to its high surface area-to-volume ratio and the easy modification of its chemical components, NL could serve as an appropriate matrix for the binding and controlled release of various pharmaceutical agents. Moreover, the challenges in the utilization of NL-based materials for cancer therapy are discussed, along with the prospects of advances in such nanomaterials for medical research applications.

Valorization of Spent coffee Grounds: A sustainable resource for Bio-based phase change materials for thermal energy storage.

Spent coffee grounds (SCGs) are waste residues arising from the process of coffee brewing and are usually sent to landfills, causing environmental concerns. SCGs contain a considerable amount of fatty acids and is therefore a promising green alternative bio-based phase change material (PCMs) compared to conventional organic and inorganic PCMs. In this study, the extraction of coffee oil from SCGs was conducted using three different organic solvents-ethanol, acetone, and hexane. The chemical composition, chemical, and thermophysical properties of these coffee oil extracts were studied to evaluate their feasibility as a bio-based PCM. Gas chromatography-mass spectroscopy (GC-MS) analysis indicated that coffee oil contains about 60-80 % of fatty acids while the phase transition temperature of the coffee oil extracts is approximately 4.5 ± 0.72 °C, with latent heat values of 51.15 ± 1.46 J/g as determined by differential scanning calorimetry (DSC). Fourier Transform Infrared Spectroscopy (FTIR) and DSC results of coffee oil extracts after thermal cycling revealed good thermal and chemical stability. An application study to evaluate coffee oil extract as a potential cold therapy modality showed that it can maintain temperatures below normal body temperature for up to 46 min. In conclusion, this work exemplifies the potential of SCGs as a promising green and sustainable resource for bio-based PCMs for low-temperature thermal energy storage applications such as cold-chain transportation and cold therapy.

Hydrogel-Based Flexible Electronics.

Flexible electronics is an emerging field of research involving multiple disciplines, which include but not limited to physics, chemistry, materials science, electronic engineering, and biology. However, the broad applications of flexible electronics are still restricted due to several limitations, including high Young's modulus, poor biocompatibility, and poor responsiveness. Innovative materials aiming for overcoming these drawbacks and boost its practical application is highly desirable. Hydrogel is a class of 3D crosslinked hydrated polymer networks, and its exceptional material properties render it as a promising candidate for the next generation of flexible electronics. Here, the latest methods of synthesizing advanced functional hydrogels and the state-of-art applications of hydrogel-based flexible electronics in various fields are reviewed. More importantly, the correlation between properties of the hydrogel and device performance is discussed here, to have better understanding of the development of flexible electronics by using environmentally responsive hydrogels. Last, perspectives on the current challenges and future directions in the development of hydrogel-based multifunctional flexible electronics are provided.

PVA/pectin composite hydrogels inducing osteogenesis for bone regeneration.

Hydrogels composed from biomolecules have gained great interests as biomaterials for tissue engineering. However, their poor mechanical properties limit their application potential. Here, we synthesized a series of tough composite hydrogels from poly (vinyl alcohol) (PVA) and pectin for bone tissue engineering. With a balance of scaffold stiffness and pore size, PVA-Pec-10 hydrogel enhanced adhesion and proliferation of osteoblasts. The hydrogel significantly promoted osteogenesis in vitro by improving the alkaline phosphates (ALP) activity and calcium biomineralization, as well as upregulating the expressions of osteoblastic genes. The composite hydrogel also accelerated the bone healing process in vivo after transplantation into the femoral defect. Additionally, our study demonstrated that pectin and its Ca2+ crosslinking network play a crucial role of inducing osteogenesis through regulating the Ca2+/CaMKII and BMP-SMAD1/5 signaling. The optimized structure composition and multifunctional properties make PVA-Pec hydrogel highly promising to serve as a candidate for bone tissue regeneration.

Dynamic Grafting of Carboxylates onto Poly(Vinyl Alcohol) Polymers for Supramolecularly-Crosslinked Hydrogel Formation.

Supramolecular hydrogels have attracted considerable interest due to their unique stimuli-responsive and self-healing properties. However, these hydrogel systems are usually achieved by covalent grafting of supramolecular units onto the polymer backbone, which in turn limits their reprocessability. Herein, we prepared a supramolecular hydrogel system by forming dynamic covalent crosslinks between 4-carboxyphenylboronic acid (CPBA) and polyvinyl alcohol (PVA). The system was then further crosslinked with either calcium ions or branched polyethylenimine (PEI) to generate hydrogels with distinctly different properties. Incorporation of calcium ions resulted in the formation of hydrogels with higher storage modulus of 7290 Pa but without self-healing properties. On the other hand, PEI-crosslinked hydrogel (PVA-CPBA-PEI) exhibited >2000% critical strain value, demonstrated high stability over 52 days and showed sustained antibacterial effect. A combination of supramolecular interactions and dynamic covalent crosslinks can be an alternate strategy to fabricate next-generation hydrogel materials.

Facile Fabrication of Lignin-Cellulose Green Nanogels.

There has been increasing exploration of the development and production of biodegradable polymers in response to issues with petrol-based polymers and their impact on the environment. Here we report a new approach to synthesize a natural nanogel from lignin and nanocellulose. First, lignin nanobeads were synthesized by a solvent-shifting method, which showed a spherical shape with a diameter of 159.7 nm. Then the lignin nanobeads were incorporated into a nanocellulose network to form the lignin/cellulose nanogels. The nanocellulose fibrils (CNF-C) nanogels reveal a higher storage modulus than the nanocellulose crystal (CNC-C) ones due to the denser network with self-entanglement of longer cellulose chains. The presence of lignin nanobeads in the nanogels helped to increase the viscoelasticity of the nanogels. This work highlights that the new kinds of green nanogels could be potentially utilized in a variety of biomedical applications such as drug delivery and wound dressing.

An economic evaluation of cabazitaxel versus a second androgen receptor-targeted agent (ARTA) for patients with metastatic castration-resistant prostate cancer previously treated with docetaxel and an ARTA: the United States payer perspective.

BACKGROUND: Cabazitaxel significantly improves clinical outcomes compared with a second androgen receptor-targeted agent (ARTA) in patients with metastatic castration-resistant prostate cancer (mCRPC) previously treated with docetaxel and an ARTA (abiraterone or enzalutamide), as demonstrated in the CARD trial (NCT02485691). We aimed to estimate healthcare costs avoided with the use of cabazitaxel as a third-line (3 L) treatment versus a second ARTA from a US payer perspective. METHODS: Model inputs were based on the CARD trial, published sources, and estimates of typical clinical care patterns by genitourinary oncologists (n = 3). Assessed time points were 6, 12, 18, and 24 months. Outcomes included progression-free survival (PFS), radiographic PFS (rPFS), and overall survival (OS); hospitalization and intensive care unit (ICU) days; and costs (reported in 2020 US dollar [USD] and converted into Euro) to manage symptomatic skeletal events (SSEs), adverse events (AEs), and end-of-life care. RESULTS: At 18 months, in a cohort of 100 patients, the use of cabazitaxel was estimated to result in 9 more patients achieving rPFS, 2 more patients achieving PFS, and 17 more survivors versus a second ARTA. The costs of SSEs, AEs, and end-of-life care were $498,909 (€424,073), $276,198 (€234,768), and $808,785 (€687,468), respectively, for cabazitaxel and $627,569 (€533,434), $251,124 (€213,455), and $1,028,294 (€874,050), respectively, for a second ARTA. Cabazitaxel was estimated to be associated with a 21% reduction in both SSE management and end-of-life care costs. Hospitalization cost was $1,442,870 (€1,226,440) for cabazitaxel and $1,728,394 (€1,469,135) for a second ARTA, representing an estimated 17% reduction in these costs. Cabazitaxel, as compared with a second ARTA, was associated with 58 fewer hospitalization days and 2 fewer ICU days and was estimated to avoid $323,095 (€274,630, 17%) in total costs, driven by SSEs management and end-of-life care. CONCLUSION: The use of cabazitaxel as a 3 L treatment after docetaxel and an ARTA in patients with mCRPC is estimated to result in clinical benefits (longer rPFS, PFS, and OS) and lower healthcare resource utilization (fewer hospitalization and ICU days), compared with a second ARTA.

PLA-lignin nanofibers as antioxidant biomaterials for cartilage regeneration and osteoarthritis treatment.

BACKGROUND: Osteoarthritis (OA) is common musculoskeletal disorders associated with overgeneration of free radicals, and it causes joint pain, inflammation, and cartilage degradation. Lignin as a natural antioxidant biopolymer has shown its great potential for biomedical applications. In this work, we developed a series of lignin-based nanofibers as antioxidative scaffolds for cartilage tissue engineering. RESULTS: The nanofibers were engineered by grafting poly(lactic acid) (PLA) into lignin via ring-opening polymerization and followed by electrospinning. Varying the lignin content in the system was able to adjust the physiochemical properties of the resulting nanofibers, including fiber diameters, mechanical and viscoelastic properties, and antioxidant activity. In vitro study demonstrated that the PLA-lignin nanofibers could protect bone marrow-derived mesenchymal stem/stromal cells (BMSCs) from oxidative stress and promote the chondrogenic differentiation. Moreover, the animal study showed that the lignin nanofibers could promote cartilage regeneration and repair cartilage defects within 6 weeks of implantation. CONCLUSION: Our study indicated that lignin-based nanofibers could serve as an antioxidant tissue engineering scaffold and facilitate the cartilage regrowth for OA treatment.

How far is Lignin from being a biomedical material?

Lignin is a versatile biomass that possesses many different desirable properties such as antioxidant, antibacterial, anti-UV, and good biocompatibility. Natural lignin can be processed through several chemical processes. The processed lignin can be modified into functionalized lignin through chemical modifications to develop and enhance biomaterials. Thus, lignin is one of the prime candidate for various biomaterial applications such as drug and gene delivery, biosensors, bioimaging, 3D printing, tissue engineering, and dietary supplement additive. This review presents the potential of developing and utilizing lignin in the outlook of new and sustainable biomaterials. Thereafter, we also discuss on the challenges and outlook of utilizing lignin as a biomaterial.

Site-specific and seasonal variation in habitat use of Eurasian otters ( Lutralutra) in western China: implications for conservation.

As a top predator, the Eurasian otter ( Lutralutra) is an indicator of healthy freshwater ecosystems and a flagship species for conservation. Once widespread in China, the species is now distributed mainly in the upper reaches of the great rivers of western China. However, a lack of knowledge on local otter populations continues to hinder their conservation in China. Here, we conducted a detailed study on habitat use of Eurasian otters in Yushu City and Tangjiahe National Nature Reserve in western China using transect surveys. At both study sites, otters preferred to defecate on large rocks close to or protruding from the river and about 50 cm above the waterline. In Yushu, no spraints were found along the 5 km river bank section in the downtown area, with otters preferring sprainting sites with natural banks, riparian zones, and lower human population density. However, this pattern was not obvious at Tangjiahe, where river transformation and human disturbance are minor. Otter river use intensity was negatively correlated with elevation and human population density in Yushu in both seasons. In Tangjiahe, otter river use intensity was positively correlated with prey mass and flow rate and negatively correlated with human population in spring, but positively correlated with human population and negatively correlated with flow rate in autumn. These results reflect the flexible habitat use strategies of otters at different sites, underlining the necessity to study otters living in different regions and habitat types. We provide suggestions for river modification and call for more site-specific studies to promote otter conservation in China.

Cationic Lignin-Based Hyperbranched Polymers to Circumvent Drug Resistance in Pseudomonas Keratitis.

The rise of antimicrobial-resistant bacteria strains has been a global public health concern due to their ability to cause increased patient morbidity and a greater burden on the healthcare system. As one of the potential solutions to overcome such bacterial infections, hyperbranched copolymers with cationic charges were developed. These copolymers were assessed for their antimicrobial efficacy and their bactericidal mechanisms. They were found to be potent against mobile colistin-resistant 1 strains, which was significant as colistin is known to be the last-resort antibiotic against Gram-negative bacteria. Furthermore, there was no sign of mutational resistance developed by E. ColiATCC 25922 and MCR 1+E. Coli against the copolymer even up to 20 passages. The ability to evade inducing resistance would provide invaluable insights for future antibiotic development. Our studies suggest that the bactericidal efficacy comes from the ability to target the outer membrane efficaciously. In vivo study using a Pseudomonas keratitis model showed that the copolymer was compatible with the eye and further supported that the copolymer treatment was effective for complete bacteria elimination.

Recycling of spent coffee grounds for useful extracts and green composites.

Large amounts of spent coffee grounds (SCGs) are often discarded and there is a need to find alternative disposal methods due to environmental concerns. This project aims to develop sustainable materials by re-purposing spent coffee grounds (SCGs). Oil extraction was performed using different organic solvents and yielded approximately 10% coffee oil. Coffee oil contains potentially useful chemical compounds such as fatty acids and caffeine. They also exhibited antioxidant properties. Extracted SCGs (ESCGs) were blended with epoxy resin to form composites. ESCG composites displayed a general decrease in mechanical properties relative to epoxy. However, improvements were observed when comparing ESCG composites and SCG composites. The greatest improvement belongs to epoxy composite filled with acetone-ESCGs, where the tensile strength, flexural modulus and flexural strength increased to 23.4 MPa, 3.02 GPa and 42.9 MPa respectively. This study presents a way to exploit waste materials which contributes to the goal of sustainability.

Facile Synthesis of Iron Oxide Nanozymes for Synergistically Colorimetric and Magnetic Resonance Detection Strategy.

Iron oxide nanomaterials with mimic enzymes activity have been paid more attention in the clinical diagnosis field. The modified surface molecules would influence the catalytic activity of nanozyme, which is worth studying. Furthermore, the traditional detection strategy is based on colorimetric change of substrates, however, the optical signal is easy to be interfered in complex biological applications. In our research, an efficient and facile preparation strategy was developed to obtain functional artificial nanozymes. Herein, three kinds of surfactants, including citrate acid, poly(ethylene glycol) bis (carboxymethyl) ether and tannic acid have been applied to modify these nanomaterials that showed uniform size, high soluble dispersity and stability. Furthermore, these nanozymes exhibited different peroxidase-like activity to catalyze the hydrogen peroxide and 3,3',5,5'-tetramethylbenzidine. More importantly, magnetic relaxation effect of iron oxide nanozymes was found to be changed during the catalytic reaction. In addition, the relationship between the magnetic signal of nanozymes and the substrate concentration showed a good linear dependence. Combined with the natural enzymes, the magnetic detection of iron oxide nanozymes also exhibited excellent substrate specificity. On these bases, a dual-function specific assay was constructed and further used for glucose detection. In conclusion, this study demonstrated an efficient iron oxide nanozymes preparation method and constructed a new synergistically colorimetric-magnetic diagnosis strategy.

Lignin-Incorporated Nanogel Serving As an Antioxidant Biomaterial for Wound Healing.

Oxidative phosphorylation is an important biological process in the body to produce energy, during which oxygen free radicals are generated as byproduct. Excessive oxygen free radicals cause cell death and reduce the rate of tissue regeneration and healing in a wound. Lignin is a natural antioxidant derived from plants, but its biomedical application is restricted because of the uncertain biocompatibility. In this work, we developed a lignin-incorporated nanogel and explored its application for wound healing. Lignin was extracted from coconut husks and determined to have strong antioxidant activity (IC50 = 25.7 ppm). Various amounts of lignin were incorporated into thermoresponsive nanogels, which were produced from polyurethane copolymers of polyethylene glycol (PEG), polypropylene glycol (PPG), and polydimethylsiloxane (PDMS). It was shown that the addition of lignin had minimal effects on the gelation and rheological properties of the nanogel but slightly increased the critical micelle concentration (CMC) of poly(PEG/PPG/PDMS urethane) copolymer from 3.38 × 10-4 g mL-1 to 4.61 × 10-4 g mL-1. The lignin-incorporated nanogels did not display detectable cytotoxicity. The lignin-incorporated nanogel possessed antioxidant activity, as it reduced the active oxygen level, protecting the LO2 cells from apoptosis caused by oxidative stress. More importantly, in vivo studies demonstrated that the lignin-incorporated nanogels accelerated the healing of burn wounds in mice as proved by the increased expression of Ki67, one marker of cell proliferation. The present work demonstrates that lignin-incorporated nanogel could serve as an antioxidant wound-dressing material and facilitate the wound healing.

Gold-decorated TiO2 nanofibrous hybrid for improved solar-driven photocatalytic pollutant degradation.

TiO2-based nanomaterials are among the most promising photocatalysts for degrading organic dye pollutants. In this work, Au-TiO2 nanofibers were fabricated by the electrospinning technique, followed by calcination in air at 500 °C. Morphological and structural analyses revealed that the composite consists of TiO2 nanofibers with embedded Au nanoparticles that are extensively distributed throughout the porous fibrous structure of TiO2. The photocatalytic performance of these Au-embedded TiO2 nanofibers was evaluated in the photodegradation of Rhodamine B and methylene blue under solar simulator irradiation. Compared with pristine TiO2 nanofibers, the Au-embedded TiO2 nanofibers displayed far better photocatalytic degradation efficiency. The plasmon resonance absorption of Au nanoparticles in the visible spectral region and the effective charge separation at the heterojunction of the Au-TiO2 hybrid are the key factors that have led to the considerable enhancement of the photocatalytic activity. The results of this study clearly demonstrate the potential of Au-TiO2 electrospun nanofibers as solar-light-responsive photocatalysts for the effective removal of dye contaminants from aquatic environments.