The synergistic effect of bulk-surface modification onto the wear resistance of the ultrahigh molecular weight polyethylene

The paper investigates the effect of bulk and surface modification on the adhesive and tribological properties of ultra-high molecular weight polyethylene (UHMWPE) and shows that bulk modification with nano- and micro-sized modifiers (montmorillonite, shungite, exfoliated graphite) mainly reduces the friction coefficient but leads to a decrease in the wear resistance of the corresponding composites. It is found that gas-phase surface fluorination provides an increase in the wear resistance of experimental samples in all cases due to a combination of nanotexturing and chemomorphological transformations of the surface layers of the modified polymers. The significant dependence of the nanotexture on the technique and mode of modification is demonstrated using the original approaches to the quantitative characterization of the experimental samples’ surfaces’ scanning electron microscopy-images (formed with the scanning electron microscope). It is shown that the surface fluorination not only makes possible to significantly compensate for the increase of the friction coefficient of bulk-modified UHMWPE in comparison with the original one but also provides a nonlinear multiplicative increase in the wear resistance.

Risedronate-loaded aerogel scaffolds for bone regeneration

Sugarcane bagasse-derived nanofibrillated cellulose (NFC), a type of cellulose with a fibrous structure, is potentially used in the pharmaceutical field. Regeneration of this cellulose using a green process offers a more accessible and less ordered cellulose II structure (amorphous cellulose; AmC). Furthermore, the preparation of cross-linked cellulose (NFC/AmC) provides a dual advantage by building a structural block that could exhibit distinct mechanical properties. 3D aerogel scaffolds loaded with risedronate were prepared in our study using NFC or cross-linked cellulose (NFC/AmC), then combined with different concentrations of chitosan. Results proved that the aerogel scaffolds composed of NFC and chitosan had significantly improved the mechanical properties and retarded drug release compared to all other fabricated aerogel scaffolds. The aerogel scaffolds containing the highest concentration of chitosan (SC-T3) attained the highest compressive strength and mean release time values (415 ± 41.80 kPa and 2.61 ± 0.23 h, respectively). Scanning electron microscope images proved the uniform highly porous microstructure of SC-T3 with interconnectedness. All the tested medicated as well as unmedicated aerogel scaffolds had the ability to regenerate bone as assessed using the MG-63 cell line, with the former attaining a higher effect than the latter. However, SC-T3 aerogel scaffolds possessed a lower regenerative effect than those composed of NFC only. This study highlights the promising approach of the use of biopolymers derived from agro-wastes for tissue engineering.

Microencapsulation based fire retardant eco-friendly jute composite

Natural fiber reinforced composites (NFCs) are a promising replacement for conventional wood materials in furniture and households. However, the flammability of natural fibers limits their practical application. The composite matrix structure can be modified to enhance flame resistance. In this study, eco-friendly and cost-effective fire-retardants (FRs), micro-integrated Triphenyl Phosphate (m-TPP), and Aluminum Trihydroxide (ATH) were added physically in different concentrations to the epoxy resins (EPs). Underwriter Laboratories 94 (UL-94) flammability test revealed that the fire resistance of FR epoxy, EP88%m-TPP9%ATH3%, increased by increasing the TPP quantity with the highest V-0 rating. The thermo-gravimetric analysis (TGA) indicated a better internal structure of EP100%. However, no char residue was observed for EP100%. The highest char residue was found for EP88%m-TPP9%ATH3%, which confirmed its highest FR resistance. However, EP88%m-TPP9%ATH3% showed poor tensile, flexural, and compressional strengths. The m-TPP was a better FR than ATH. However, the mechanical stability of FR samples containing ATH is better than those containing m-TPP. Also, the addition of FRs reduced the tensile and flexural strengths; however, the compressional strength and modulus were significantly improved, which implied a potential use in the furniture industry.

Migration of surface-associated microbial communities in spaceflight habitats

Astronauts are spending longer periods locked up in ships or stations for scientific and exploration spatial missions. The International Space Station (ISS) has been inhabited continuously for more than 20 years and the duration of space stays by crews could lengthen with the objectives of human presence on the moon and Mars. If the environment of these space habitats is designed for the comfort of astronauts, it is also conducive to other forms of life such as embarked microorganisms. The latter, most often associated with surfaces in the form of biofilm, have been implicated in significant degradation of the functionality of pieces of equipment in space habitats. The most recent research suggests that microgravity could increase the persistence, resistance and virulence of pathogenic microorganisms detected in these communities, endangering the health of astronauts and potentially jeopardizing long-duration manned missions. In this review, we describe the mechanisms and dynamics of installation and propagation of these microbial communities associated with surfaces (spatial migration), as well as long-term processes of adaptation and evolution in these extreme environments (phenotypic and genetic migration), with special reference to human health. We also discuss the means of control envisaged to allow a lasting cohabitation between these vibrant microscopic passengers and the astronauts.

Targeted PERK inhibition with biomimetic nanoclusters confers preventative and interventional benefits to elastase-induced abdominal aortic aneurysms

Abdominal aortic aneurysm (AAA) is a progressive aortic dilatation, causing ∼80% mortality upon rupture. Currently, there is no approved drug therapy for AAA. Surgical repairs are invasive and risky and thus not recommended to patients with small AAAs which, however, account for ∼90% of the newly diagnosed cases. It is therefore a compelling unmet clinical need to discover effective non-invasive strategies to prevent or slow down AAA progression. We contend that the first AAA drug therapy will only arise through discoveries of both effective drug targets and innovative delivery methods. There is substantial evidence that degenerative smooth muscle cells (SMCs) orchestrate AAA pathogenesis and progression. In this study, we made an exciting finding that PERK, the endoplasmic reticulum (ER) stress Protein Kinase R-like ER Kinase, is a potent driver of SMC degeneration and hence a potential therapeutic target. Indeed, local knockdown of PERK in elastase-challenged aorta significantly attenuated AAA lesions in vivo. In parallel, we also conceived a biomimetic nanocluster (NC) design uniquely tailored to AAA-targeting drug delivery. This NC demonstrated excellent AAA homing via a platelet-derived biomembrane coating; and when loaded with a selective PERK inhibitor (PERKi, GSK2656157), the NC therapy conferred remarkable benefits in both preventing aneurysm development and halting the progression of pre-existing aneurysmal lesions in two distinct rodent models of AAA. In summary, our current study not only establishes a new intervention target for mitigating SMC degeneration and aneurysmal pathogenesis, but also provides a powerful tool to facilitate the development of effective drug therapy of AAA.

3D-printed fish gelatin scaffolds for cartilage tissue engineering

Knee osteoarthritis is a chronic disease caused by the deterioration of the knee joint due to various factors such as aging, trauma, and obesity, and the nonrenewable nature of the injured cartilage makes the treatment of osteoarthritis challenging. Here, we present a three-dimensional (3D) printed porous multilayer scaffold based on cold-water fish skin gelatin for osteoarticular cartilage regeneration. To make the scaffold, cold-water fish skin gelatin was combined with sodium alginate to increase viscosity, printability, and mechanical strength, and the hybrid hydrogel was printed according to a pre-designed specific structure using 3D printing technology. Then, the printed scaffolds underwent a double-crosslinking process to enhance their mechanical strength even further. These scaffolds mimic the structure of the original cartilage network in a way that allows chondrocytes to adhere, proliferate, and communicate with each other, transport nutrients, and prevent further damage to the joint. More importantly, we found that cold-water fish gelatin scaffolds were nonimmunogenic, nontoxic, and biodegradable. We also implanted the scaffold into defective rat cartilage for 12 weeks and achieved satisfactory repair results in this animal model. Thus, cold-water fish skin gelatin scaffolds may have broad application potential in regenerative medicine.

Prevention strategies of postoperative adhesion in soft tissues by applying biomaterials: Based on the mechanisms of occurrence and development of adhesions

Postoperative adhesion (POA) widely occurs in soft tissues and usually leads to chronic pain, dysfunction of adjacent organs and some acute complications, seriously reducing patients' quality of life and even being life-threatening. Except for adhesiolysis, there are few effective methods to release existing adhesion. However, it requires a second operation and inpatient care and usually triggers recurrent adhesion in a great incidence. Hence, preventing POA formation has been regarded as the most effective clinical strategy. Biomaterials have attracted great attention in preventing POA because they can act as both barriers and drug carriers. Nevertheless, even though much reported research has been demonstrated their efficacy on POA inhibition to a certain extent, thoroughly preventing POA formation is still challenging. Meanwhile, most biomaterials for POA prevention were designed based on limited experiences, not a solid theoretical basis, showing blindness. Hence, we aimed to provide guidance for designing anti-adhesion materials applied in different soft tissues based on the mechanisms of POA occurrence and development. We first classified the postoperative adhesions into four categories according to the different components of diverse adhesion tissues, and named them as "membranous adhesion", "vascular adhesion", "adhesive adhesion" and "scarred adhesion", respectively. Then, the process of the occurrence and development of POA were analyzed, and the main influencing factors in different stages were clarified. Further, we proposed seven strategies for POA prevention by using biomaterials according to these influencing factors. Meanwhile, the relevant practices were summarized according to the corresponding strategies and the future perspectives were analyzed.

Chemically revised conducting polymers with inflammation resistance for intimate bioelectronic electrocoupling

Conducting polymers offer attractive mixed ionic-electronic conductivity, tunable interfacial barrier with metal, tissue matchable softness, and versatile chemical functionalization, making them robust to bridge the gap between brain tissue and electronic circuits. This review focuses on chemically revised conducting polymers, combined with their superior and controllable electrochemical performance, to fabricate long-term bioelectronic implants, addressing chronic immune responses, weak neuron attraction, and long-term electrocommunication instability challenges. Moreover, the promising progress of zwitterionic conducting polymers in bioelectronic implants (≥4 weeks stable implantation) is highlighted, followed by a comment on their current evolution toward selective neural coupling and reimplantable function. Finally, a critical forward look at the future of zwitterionic conducting polymers for in vivo bioelectronic devices is provided.

Fabrication of a sensitive electrochemical sensor based on hybrid polyamide/chromotropic acid nanofibers electrospun on glassy carbon electrode for Hg(2+) sensing in drinking water and canned fish samples

In this study, a new electrochemical sensor was designed based on a hybrid of polyamide (PA) and chromotropic acid (CA) nanofibers electrospun on a glassy carbon electrode (GCE) configured as PANFs-CANFs/GCE. The electrochemical response of this sensor showed an excellent electrochemical activity for the detection of Hg²⁺ ions using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods. The proposed sensor exhibited the prominent electrocatalytic value of (α = 0.60, Log Ks = 3.45 s^-1 and Γ = 3.30 × 10 ^-9 mmol/cm²) as a result of PANFs-CANFs/GCE response to Hg²⁺ ions. The recommended sensor also demonstrated a linear portion in the calibration curve over the concentration range of 30 to 450 nM with the limit of detection (LOD) and limit of quantitation (LOQ) of 9.98 nM and 29.97 nM, respectively. The fabricated sensor revealed reproducible and repeatable responses with a high level of stability. Therefore, we highly recommend this new electro-spun based sensor for quantifying Hg²⁺ in drinking water and canned fish samples with the accurate and precise results and no side interferences.

Synergistic effect of lecithin and alginate, CMC, or PVP in stabilizing curcumin and its potential mechanism

This work aims to advance the understanding of the synergistic mechanism of lecithin and polymers (alginate, CMC, and PVP) in stabilizing curcumin, with a major focus on understanding the nanocomplex formation process and the main binding energy between molecules. It is demonstrated that lecithin and polymers have a synergistic effect in increasing the thermal acid, light, and digestion stability of curcumin. The potential mechanism is that the hydrophobic parts of curcumin molecules are first anchored at the region of the hydrophobic cavity of lecithin by van der Waals, while the hydrophilic parts are outward and are further encapsulated by hydrophilic polymers by van der Waals and electrostatic interaction to form a protective shell. This study contributes to our understanding of the synergistic mechanism of lecithin, polymers, and hydrophobic compounds, which can promote the synergistic use of lecithin and polymers to prepare nanocomplexes as an important tool for delivering bioactive compounds.

Bimetallic (AuAg, AuPd and AgPd) nanoparticles supported on cellulose-based hydrogel for reusable catalysis

Biopolymer-derived hydrogels with low-cost and sustainable features have been considered as fascinating supported materials for metal nanoparticles. Cellulose, as the most abundant biopolymer, is a renewable raw material to prepare biopolymer-derived hydrogels for catalysis. Here, a cellulose-based hydrogel is designed to load bimetallic (AuAg, AuPd and AgPd) nanoparticles. 4-Nitrophenol reduction and Suzuki-Miyaura coupling reactions are selected to evaluate and compare the catalytic performance of the resulting bimetallic nanoparticle-loaded cellulose-based composite hydrogels. The bimetallic nanocomposite hydrogels are easy to be recycled over 10 times during the catalytic experiments and possess good applicability and generality for various substrates. The catalytic activity of bimetallic nanocomposite hydrogels was compared with recent literatures. In addition, the possible catalytic mechanism is also proposed. This work is expected to give a new insight for designing and preparing bimetallic nanoparticle-based cellulose hydrogels and proves its applicability and prospect in the catalytic field.

Synthesis of porous dimethoxypillar[5]arene knitted β-cyclodextrin copolymers for efficient adsorption of organic micropollutants

Herein, through knitting benzylated β-cyclodextrin (BnCD) by dimethoxypillar[5]arene (P[5]), porous copolymers (P[5]-BnCDs) containing two kinds of macrocycles were synthesized with yields not <97 %. The molar ratio of P[5]/BnCD greatly influenced the P[5]-BnCDs' porosity and adsorption performance. When the molar ratio of P[5]/BnCD was 4/1, the P[5]-BnCD (4-1), demonstrated a surface area up to 515.95 m²/g and showed fast adsorption kinetic, high adsorption capacity and good reusability towards the model organic micropollutants (OMPs). The adsorption fitted well with the pseudo-second-order and the Langmuir models, while the thermodynamic studies revealed spontaneous physisorption process. The adsorption mechanism was dominant by host-guest and hydrophobic interactions and the adsorption at environmentally relevant concentrations experiments showed the practicality and superiority in extraction of the OMPs at μg/L level. This study paves a way for the development of versatile porous organic polymers with multiple macrocycles for efficient removal of OMPs from water.

An in vitro model that mimics the foreign body response in the peritoneum: Study of the bioadhesive properties of HA-based materials

A cascade of reactions known as the foreign body response (FBR) follows the implantation of biomaterials leading to the formation of a fibrotic capsule around the implant and subsequent health complications. The severity of the FBR is driven mostly by the physicochemical characteristics of implanted material, the method and place of implantation, and the degree of immune system activation. Here we present an in vitro model for assessing new materials with respect to their potential to induce a FBR in the peritoneum. The model is based on evaluating protein sorption and cell adhesion on the implanted material. We tested our model on the free-standing films prepared from hyaluronan derivatives with different hydrophobicity, swelling ratio, and rate of solubilization. The proteomic analysis of films incubated in the mouse peritoneum showed that the presence of fibrinogen was driving the cell adhesion. Neither the film surface hydrophobicity/hydrophilicity nor the quantity of adsorbed proteins were decisive for the induction of the long-term cell adhesion leading to the FBR, while the dissolution rate of the material proved to be a crucial factor. Our model thus helps determine the probability of a FBR to materials implanted in the peritoneum while limiting the need for in vivo animal testing.

Tuning interfacial microstructure of alginate-based amphiphile by dynamic bonding for stabilizing Pickering emulsion

Polysaccharide-based soft colloidal particles mediated by the dynamic bonding-engineered interfacial self-assembly can regulate the properties of oil-water interfacial films, availing the stability of emulsions under a wide pH range. The amphiphilic phenylboronic alginate soft colloidal particles (Alg-PBA) were designed to stabilize pH-responsive Pickering emulsions (PEs). Combining stability analysis with quartz crystal microbalance and dissipation monitoring (QCM-D), the microstructure and viscoelasticity of Alg-PBA at the oil-water interface were determined. The results showed that PEs stabilized by Alg-PBA due to a thicker and stronger viscoelastic interface film induced by BO bonds and hydrogen bonds. The structure-function relationship of the Alg-PBA emulsifier driven by dynamic bonds was further elaborated at multiple scales by laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). Meanwhile, the microstructure of aerogels templated by emulsion could be tuned by adjusting dynamic bonds, which provides a new idea for polysaccharide soft material engineering.

Targeted release of soybean peptide from CMC/PVA hydrogels in simulated intestinal fluid and their pharmacokinetics

Carboxymethyl cellulose (CMC)/polyvinyl alcohol (PVA) hydrogels loaded with soybean peptide (SPE) were fabricated via a freeze-thaw method. These hydrogels conquer barriers in simulated gastric fluid (SGF), and then release SPE in simulated intestinal fluid (SIF). The results of in vitro SPE release from these hydrogels showed that in SGF only a little of the SPE released, but in SIF the SPE was completely released. The released SPE had scavenging rates for DPPH and ABTS free radicals of 41.68 and 31.43 %. The pharmacokinetic model of SPE release from the hydrogels in SIF was studied. When the hydrogels are moved from SGF to SIF, the sorption of the shrinkage hydrogel network is entirely controlled by stress-induced relaxations. There are swollen and shrunken regions during SPE release. For SPE release into the SIF, SPE has to be freed from the weak bonds in the swollen regions by changes in the conformation of CMC and PVA. The release rate of SPE was found to be governed by the diffusion and swelling rate of the shrinkage hydrogel network. The Korsmeyer-Peppas equation diffusion exponents (n) for SPE release from the hydrogels are >2.063, indicating a super case II transport. These data demonstrate CMC/PVA hydrogels have potential applications in oral peptide delivery.