Wound healing is a complicated and continuous process affected by several factors, which needs an appropriate surrounding to achieve accelerated healing. Wound healing process recruits three different phases: inflammation, proliferation, and maturation. Due to the different types of wounds, as well as the advancement in medical technology, various products have been developed to repair different skin lesions. Our objective is to investigate the advancement in wound dressings from traditional to the current methods of treatment. The article presents the characteristics of an ideal wound dressing, the requirements for the appropriate selection of different types of wounds, and a detailed classification of wound dressings. Animal origin, herbal origin, and synthetic dressings are firstly introduced and reviewed. Then, nonmedicated dressings including alginate, hydrogel, and hydrocolloid dressings, as well as medicated dressings are discussed. Finally, the developmental prospectives of the new generations of wound dressings for future researches are presented. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47738.

The development of stretchable sensors has recently attracted considerable attention. These sensors have been used in wearable and robotics applications, such as personalized health-monitoring, motion detection, and human-machine interfaces. Herein, we report on a highly stretchable electrochemical pH sensor for wearable point-of-care applications that consists of a pH-sensitive working electrode and a liquid-junction-free reference electrode, in which the stretchable conductive interconnections are fabricated by laser carbonizing and micromachining of a polyimide sheet bonded to an Ecoflex substrate. This method produces highly porous carbonized 2D serpentine traces that are subsequently permeated with polyaniline (PANI) as the conductive filler, binding material, and pH-sensitive membrane. The experimental and simulation results demonstrate that the stretchable serpentine PANI/C-PI interconnections with an optimal trace width of 0.3 mm can withstand elongations of up to 135% and are robust to more than 12 000 stretch-and-release cycles at 20% strain without noticeable change in the resistance. The pH sensor displays a linear sensitivity of -53 mV/pH (r = 0.976) with stable performance in the physiological range of pH 4-10. The sensor shows excellent stability to applied longitudinal and transverse strains up to 100% in different pH buffer solutions with a minimal deviation of less than ±4 mV. The material biocompatibility is confirmed with NIH 3T3 fibroblast cells via PrestoBlue assays.

Blends of recycled polycarbonate (PC) and acrylonitrile-butadiene-styrene (ABS) were prepared and some mechanical and morphological properties were investigated. To compatibilize these blends, ABS-g-(maleic anhydride) (ABS-g-MA) and (ethylene-vinyl acetate)-g-(maleic anhydride) (EVA-g-MA) with similar degree of grafting of 1.5% were used. To compare the effect of the type of compatibilizer on mechanical properties, blends were prepared using 3, 5 and 10 phr of each compatibilizer. A co-rotating twin-screw extruder was used for blending. The results showed that ABS-g-MA had no significant effect on the tensile strength of the blends while EVA-g-MA decreased the tensile strength, the maximum decrease being about 9.6% when using 10 phr of this compatibilizer. The results of notched Charpy impact strength tests showed that EVA-g-MA increased the impact strength of blends more than ABS-g-MA. The maximum value of this increase occurred when using 5 phr of each compatibilizer, it being about 54% for ABS-g-MA and 165% for EVA-g-MA. Scanning electron microscopy micrographs showed that the particle size of the dispersed phase was decreased in the continuous phase of PC by using the compatibilizers. Moreover, a blend without compatibilizer showed brittle behaviour while the blends containing compatibilizer showed ductile behaviour in fracture.

Treatments of skin injuries caused by trauma and diseases are among the most considerable medical problems. The use of scaffolds that can cover the wound area and support cellular ingrowth has shown great promise. However, mimicking the physicochemical properties of the native skin extracellular matrix (ECM) is essential for the successful integration of these scaffolds. Elastin has been known as the second main protein-based component of the native skin ECM. In this research, scaffolds containing gelatin, cellulose acetate, and elastin were fabricated using electrospinning. Subsequently, the effects of soluble elastin on the physical, mechanical, and biological properties of the prepared scaffolds were studied. The results confirmed that the presence of elastin in the composition changed the fiber morphology from straight to ribbon-like structure and decreased the swelling ratio and degradation rate of the scaffold. In vitro experiments showed that elastin-containing scaffolds supported the attachment and proliferation of fibroblast cells. Overall, the obtained results suggest the ternary blend of gelatin, cellulose acetate, and elastin as a good candidate for skin tissue engineering.

Today's medicine mainly relies on conventional means of therapeutics delivery to the human body, such as tablets, capsules, syrups, and injectable drugs. Utilizing such techniques are associated with a number of drawbacks including the need of high drug dosage, causing transient drug concentration changes in the patient's body, poor solubility, poor bioavailability, drug degradation, and interaction with the biological environment (enzymes and proteins). To address these issues, nanotechnology-based novel drug delivery methods are proposed. Among the plethora of novel drug delivery techniques, the use of polymeric nanocarriers is shown to be promising. In fact, they focus on three main questions: first, where should a drug be released? Second, when should the drug be released? And finally, how should the drug be released? In this review, we are confined to explaining some concepts regarding to polymeric nanocarriers. First, different kinds of polymeric nanocarriers have been explained, in terms of their structures and properties. Second, different fabrication methods, for each one, have been elaborated. Finally, a handful of works carried out have been reviewed for their special structure, their kind of polymers which is used, and the drug which is encapsulated.

In this research, a bilayer coating has been applied on the surface of 316 L stainless steel (316LSS) to provide highly proliferated metallic implants for bone regeneration. The first layer was prepared using electrophoretic deposition of graphene oxide (GO), while the top layer was coated utilizing electrospinning of poly (ε-caprolactone) (PCL)/gelatin (Ge)/forsterite solutions. The morphology, porosity, wettability, biodegradability, bioactivity, cell attachment and cell viability of the prepared coatings were evaluated. The Field Emission Scanning Electron Microscopy (FESEM) results revealed the formation of uniform, continuous, and bead-free nanofibers. The Energy Dispersive X-ray (EDS) results confirmed well-distributed forsterite nanoparticles in the structure of the top coating. The porosity of the electrospun nanofibers was found to be above 70%. The water contact angle measurements indicated an improvement in the wettability of the coating by increasing the amount of nanoparticles. Furthermore, the electrospun nanofibers containing 1 and 3 wt.% of forsterite nanoparticles showed significant bioactivity after soaking in the simulated body fluid (SBF) solution for 21 days. In addition, to investigate the in vitro analysis, the MG-63 cells were cultured on the PCL/Ge/forsterite and GO-PCL/Ge/forsterite coatings. The results confirmed an excellent cell adhesion along with considerable cell growth and proliferation. It should be also noted that the existence of the forsterite nanoparticles and the GO layer substantially enhanced the cell proliferation of the coatings.

This research studies the effect of using a grid-like pattern as a collector on increasing the pore size of the electrospun gelatin/cellulose acetate/elastin scaffolds. The morphological study showed an enlargement in pore size and a decline in fiber diameter in comparison with the scaffold fabricated using conventional flat sheet collectors. The use of the pattern increased the swelling ratio and degradation rate of the scaffold. Investigating the tensile properties of scaffolds revealed that the patterned collector increased the elongation at break up to 145%. In vitro experiments revealed the patterned scaffold as a good substrate for attachment and proliferation of fibroblast cells. Overall, our results indicated that the patterned scaffold of gelatin/cellulose acetate/elastin could provide a better microenvironment for fibroblast cells compared to the conventional scaffolds. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 370-376, 2018.

In this study, the effect of organo-modified montmorillonite on mechanical and gas barrier properties of nanocomposite films of linear low-density polyethylene/lowdensity polyethylene blends was investigated. Two different compatibilizers, polyethylene grafted maleic anhydride and polypropylene grafted maleic anhydride, were used to obtain a better dispersion of the nanoclay in the blends. The blend samples containing various amounts of the clay were melt compounded and then blown to films. Mechanical properties of the films were studied in machine and transverse directions. A constant volume-variable pressure method was used to determine the gas permeability of the films. Addition of the 4 parts per hundred nanoclay improved the tensile modulus in machine direction by about 59% and that in transverse direction by about 100%. It further reduced the oxygen permeability by about 38%.