Therapeutic effects of electrospun chitosan nanofibers on animal skin wounds: A systematic review and meta-analysis

Electrospun chitosan nanofibers (QSNFs) enhance the healing process by mimicking skin structure and function. The aim of this study was to analyze the therapeutic effects of QSNFs application on animal skin wounds to identify a potential direction for translational research in dermatology. The PRISMA methodology and the PICO scheme were used. A random effects model and mean difference analysis were applied for the meta-analysis. A meta-regression model was constructed, risk of bias was determined, and methodological quality assessment was performed. Of the 2370 articles collected, 54 studies were selected based on the inclusion and exclusion criteria. The wound healing area was used for building models on the 3rd, 7th, and 14th days of follow-up; the results were - 10.4% (95% CI, -18.2% to -2.6%, p = 0.001), -21.0% (95% CI, -27.3% to -14.7%, p = 0.001), and - 14.0% (95% CI, -19.1 to -8.8%, p = 0.001), respectively. Antioxidants and synthetic polymers combined with QSNFs further reduced skin wound areas (p < 0.05). The results show a more efficient reduction in wound area percentages in experimental groups than in control groups, so QSNFs could potentially be applied in translational human medicine research.

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.

Quasi-static compressive behaviour of epoxy composites reinforced with crumb rubber

Quasi static compressive response of crumb rubber-epoxy composites was examined by varying the crumb rubber composition (0, 10, 20 and 30 vol.%). All the composites, irrespective of the strain rates, depict elastic regions tailed by a wide plateau area that is credited with the densification of rubber particulates. Higher strains to failure of composites were revealed as compared with neat epoxy signifying higher energy absorption ability of constituents. The modulus of elasticity of composites was noted to be lower than neat epoxy specimens, irrespective of the strain rates. Irrespective of strain rates, the strength of all the composites were inferior to neat epoxy specimens. Energy absorption of EC-30 was higher compared to EC-20 and EC-10 and noted to be increased in the range of 6–14% for 0.1 mm/min strain rate while it increases in the range of 5–9% for 0.01 mm/min strain rate, respectively. Rubber-toughening mechanism was credited with the increase in energy absorption of composites. Higher energy absorption of composites was mainly due to higher strain realisation indicating more deformation ability. Fracture features of specimens were analysed by scanning electron microscope.

Optimization of hyaluronan-enriched cubosomes for bromfenac delivery enhancing corneal permeation: characterization, ex vivo, and in vivo evaluation

To design and evaluate hyaluronan-based cubosomes loaded with bromfenac sodium (BS) for ocular application to enhance the corneal permeation and retention in pterygium and cataract treatment. BS-loaded cubosomes were prepared by the emulsification method, employing 2³ full factorial design using Design-Expert® software. Glycerol monoolein (GMO) and poloxamer 407 (P407) as lipid phase and polyvinyl alcohol (PVA) as stabilizer were the used ingredients. The optimized formulation (OBC; containing GMO (7% w/w), P407 (0.7% w/w) and PVA (2.5% w/w)) was further evaluated. OBC had an entrapment efficiency of 61.66 ± 1.01%, a zeta potential of -30.80 ± 0.61 mV, a mean particle size of 149.30 ± 15.24 nm and a polydispersity index of 0.21 ± 0.02. Transmission electron microscopy confirmed its cubic shape and excellent dispersibility. OBC exhibited high stability and no ocular irritation that was ensured by histopathology. Ex vivo permeation study showed a significant increase in drug deposition and permeability parameters through goat cornea, besides, confocal laser microscopy established the superior permeation capability of OBC, as compared to drug solution. In vivo pharmacokinetics in aqueous humor indicated higher AUC_0-tlast (18.88 µg.h/mL) and mean residence time (3.16 h) of OBC when compared to the marketed eye drops (7.93 µg.h/mL and 1.97 h, respectively). Accordingly, hyaluronan-enriched cubosomes can be regarded as a promising carrier for safe and effective topical ocular delivery.

Bioinspired MXene-Based Soft Actuators Exhibiting Angle-Independent Structural Color

In nature, many living organisms exhibiting unique structural coloration and soft-bodied actuation have inspired scientists to develop advanced structural colored soft actuators toward biomimetic soft robots. However, it is challenging to simultaneously biomimic the angle-independent structural color and shape-morphing capabilities found in the plum-throated cotinga flying bird. Herein, we report biomimetic MXene-based soft actuators with angle-independent structural color that are fabricated through controlled self-assembly of colloidal SiO2 nanoparticles onto highly aligned MXene films followed by vacuum-assisted infiltration of polyvinylidene fluoride into the interstices. The resulting soft actuators are found to exhibit brilliant, angle-independent structural color, as well as ultrafast actuation and recovery speeds (a maximum curvature of 0.52 mm−1 can be achieved within 1.16 s, and a recovery time of ~ 0.24 s) in response to acetone vapor. As proof-of-concept illustrations, structural colored soft actuators are applied to demonstrate a blue gripper-like bird’s claw that can capture the target, artificial green tendrils that can twine around tree branches, and an artificial multicolored butterfly that can flutter its wings upon cyclic exposure to acetone vapor. The strategy is expected to offer new insights into the development of biomimetic multifunctional soft actuators for somatosensory soft robotics and next-generation intelligent machines.

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.

Self-Modifying Nanointerface Driving Ultrahigh Bidirectional Thermal Conductivity Boron Nitride-Based Composite Flexible Films

While boron nitride (BN) is widely recognized as the most promising thermally conductive filler for rapidly developing high-power electronic devices due to its excellent thermal conductivity and dielectric properties, a great challenge is the poor vertical thermal conductivity when embedded in composites owing to the poor interfacial interaction causing severe phonon scattering. Here, we report a novel surface modification strategy called the “self-modified nanointerface” using BN nanocrystals (BNNCs) to efficiently link the interface between BN and the polymer matrix. Combining with ice-press assembly method, an only 25 wt% BN-embedded composite film can not only possess an in-plane thermal conductivity of 20.3 W m−1 K−1 but also, more importantly, achieve a through-plane thermal conductivity as high as 21.3 W m−1 K−1, which is more than twice the reported maximum due to the ideal phonon spectrum matching between BNNCs and BN fillers, the strong interaction between the self-modified fillers and polymer matrix, as well as ladder-structured BN skeleton. The excellent thermal conductivity has been verified by theoretical calculations and the heat dissipation of a CPU. This study provides an innovative design principle to tailor composite interfaces and opens up a new path to develop high-performance composites.

Design and Testing of a Novel Piezoelectric-Driven Microvibration Hammerhead

A novel microvibration hammerhead consists of a piezoelectric actuator and a double cross-shape compliant mechanism (DCCM) is presented in this paper. The output force of the piezoelectric actuator can be detected in real time by an inside-installed pressure sensor. A theoretical model including the stiffness, first natural frequency, and stress of the DCCM and the displacement output of the piezoelectric actuator are established, and then they are further analyzed using the finite element analysis method. The effects of the beam thickness on the static and dynamic properties are deeply analyzed and compared. A prototype micro hammering system is constructed by integrating the microvibration hammerhead assembly and controlling system. Various experiments are also carried out to verify the basic performance of the micro hammering system.

A sustained-release microcarrier effectively prolongs and enhances the antibacterial activity of lysozyme

Bacterial infections have become a great threat to public health in recent years. A primary lysozyme is a natural antimicrobial protein; however, its widespread application is limited by its instability. Here, we present a poly (N-isopropylacrylamide) hydrogel inverse opal particle (PHIOP) as a microcarrier of lysozyme to prolong and enhance the efficiency against bacteria. This PHIOP-based lysozyme (PHIOP-Lys) formulation is temperature-responsive and exhibits long-term sustained release of lysozyme for up to 16 days. It shows a potent antibacterial effect toward both Escherichia coli and Staphylococcus aureus, which is even higher than that of free lysozyme in solution at the same concentration. PHIOPs-Lys were demonstrated to effectively inhibit bacterial infections and enhance wound healing in a full-thickness skin wound rat model. This study provides a novel pathway for prolonging the enzymatic activity and antibacterial effects of lysozyme.