Development and characterization of a poly (vinyl alcohol) and sodium alginate blend foam for wound dressing loaded with propolis and all-trans retinoic acid

Propolis is a complex mixture of phytochemicals, with antibacterial, anti-inflammatory, and healing properties. All-trans retinoic acid is implicated in wound healing by stimulating angiogenesis, cell recruitment, extracellular matrix deposition, and reepithelization. The incorporation of both agents to a polymeric wound dressing composed of poly (vinyl alcohol) and sodium alginate may result in improved healing allied to controlled release, fluid uptake, and wound protection. In the present work, we have physically characterized this wound dressing and analyzed its release kinetics. The anti-inflammatory capacity was assayed. SEM images showed a highly porous structure with a diverse morphology. FTIR spectra displayed a highly cross-linked structure with both polymers connected by hydrogen bonds and acetal bridges. The wound dressings were able to retain great volumes of PBS. Propolis and vitamin A releasing behavior were maintained for 6 h. The concentrations of the biologically active substances were capable of promoting anti-inflammatory action in an erythrocyte membrane stabilization model. The wound dressings obtained here showed adequate physical properties. The fabrication process did not affect the anti-inflammatory capacity. Further tests are needed to ensure the biocompatibility and to assess other biological activities of the therapeutic agents.     

Physicochemical properties and antimicrobial activity of biocompatible carboxymethylcellulose‐silver nanoparticle hybrids for wound dressing and epidermal repair

Skin loss can be caused by accident, burn, trauma, chronic wounds, and diseases, which is severely aggravated by multidrug‐resistant bacterial infections. Soft hybrids based on biopolymers combined with silver nanoparticles (AgNPs) have potential applications as wound dressing supports and skin tissue repair. Thus, our study focused on the design, green synthesis, and comprehensive characterization of carboxymethyl cellulose (CMC–AgNP) nanocomposites for producing hydrogel membranes, with tunable physicochemical properties, cytocompatibility, and biocidal activity for potential application as wound dressing and skin repair. These nanocomposites were prepared using CMC with two degrees of carboxymethylation, distinct concentrations of citric acid (CA) crosslinker, and AgNPs by in situ chemical reduction, forming hybrid membranes by the solvent casting method. The results demonstrated that superabsorbent hydrogels were produced with swelling and degradation behaviors dependent on the concentration of CA crosslinker, degree of carboxymethylation of CMC, and content of AgNP in the matrices. Moreover, the Fourier transform infrared spectroscopy analysis evidenced that the CMC functional groups (e.g., ? COOH and ? OH) were directly involved in the chemical reactions for the formation of AgNPs and hydrogel crosslinking pathway. These nanocomposites were cytocompatible using in vitro 3‐(4,5‐dimethyl‐2‐thiazolyl)‐2,5‐diphenyltetrazolium bromide cell viability assay with of human embryonic kidney cells. Conclusively, the CMC–AgNP nanohybrids demonstrated to be simultaneously non‐toxic combined with highly effective antibacterial activity against gram‐positive multi‐resistant wound/skin pathogens (Staphylococcus aureus) and moderate effect towards gram‐negative strains (Escherichia coli and Pseudomonas aeruginosa). © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45812.     

Analyzing the interactions and miscibility of silk fibroin/mucin blends

Mucin, a glycoprotein with viscoelastic properties, and silk fibroin, a protein excreted from silkworms with properties of thermal and mechanical resistance, have been probed as building blocks in the design of biomaterials. Aiming to evaluate the interaction and miscibility between mucin and fibroin, we synthesized silk fibroin and mucin (SF/MU) blends for biomedical applications. The morphological analysis of the SF/MU blends showed the presence of two phases, suggesting a partial miscibility between the polymers. The degradation temperature of the SF/MU blends increased with an increase in the silk fibroin content, indicating that silk fibroin contributed to the thermal stability of the blends. The glass transition temperature of the SF/MU blends lay between the values of the pure polymers. The Fourier-transform infrared spectroscopy results pointed out that the interaction between fibroin and mucin occurred between the amine group of silk fibroin and mucin carboxyl and hydroxyl groups. The outcomes of this work provided essential information on the miscibility of the SF/MU blends. These findings will be critical for further studies with fibroin and mucin-based biomaterials, especially in mucoadhesive systems and wound healing applications.     

Process optimization of electrospun silk fibroin fiber mat for accelerated wound healing

Considering the outstanding biocompatibility of Bombyx mori silk fibroin, this study is designed to fabricate biomimetic nanofibrous structure made of silk fibroin, which can enhance cell activities for tissue formation. The electrospinning of blend of silk fibroin with low molecular weight poly(ethylene‐oxide) (PEO) is explored with ease of preparation for high productivities. The average diameter of electrospun silk fibroin (eSF) is decreased from 414 ± 73 to 290 ± 46 nm after PEO extraction. To induce the desired cellular activity, the surface of the eSF fibers is modified with fibronectin by using the carbodiimide chemistry method. The potential use of the obtained wound healing material is assessed by indirect cytotoxicity evaluation on normal human dermal fibroblast (NHDF) in terms of their attachment and cell proliferation. The surface‐modified eSF nanofiber mats show good support for cellular adhesion and spreading as a result of fibronectin grafting on the fiber surface, especially for cell migration inside the fibrous structure. These results demonstrate a new fabrication technique of surface‐modified silk fibroin electrospun nanofibers for biomedical application; with the ability to accelerate wound healing. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3634–3644, 2013     

Design of an antibacterial gelatin based on a covalent protein–protein coupling

An antibacterial peptide (AMP), i.e., nisin, was covalently bound to gelatin through a protein–protein coupling. Various reaction conditions were tested to study and optimize parameters of grafting e.g., orientation and density of AMP, which could impact the final antibacterial activity of the modified biopolymer. Modification was investigated by Fourier transform infrared (FT‐IR) spectroscopy and zeta potential. The antibacterial activity of the nisin‐enriched gelatin was evaluated against two staphylococci bacterial strains, i.e., Staphylococus epidermidis and Staphylococcus aureus. A higher activity was found for gelatin modified at pH = 7.4 revealing an influence of the nisin orientation on the protein antibacterial property. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41825.     

Thermoresponsive hydrogels based on renewable resources

This work aims to synthesize novel thermoresponsive hydrogels from renewable resources, bacterial cellulose (BC), and castor oil (CO), and to investigate the effect of CO on physical and thermal behaviors of BC/Poly(N-isopropylacrylamide) (PNIPAM) hydrogels. The structural properties of the hydrogels are analyzed by Fourier-transform infrared (FTIR) spectroscopy. Differential scanning calorimeter (DSC) technique and thermogravimetric analysis (TGA) are also performed to examine the thermal properties of the hydrogels. The morphological differences of the hydrogels are analyzed by scanning electron microscope (SEM). The thermoresponsive performances of the hydrogels are examined by swelling and deswelling behaviors. The hydrogel with CO is found to be more sensitive to temperature changes than the one without CO. Deswelling study demonstrates 91 and 25% of water loss for hydrogels with and without CO, respectively. The present study shows a novel approach to synthesize thermoresponsive hydrogels with renewable resources for biomedical applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48861.     

Optimization of cinnamaldehyde microcapsule wall materials by experimental and quantitative methods

Microencapsulation is a widely-investigated technique used for the unstable material preservation since the wall materials prevent the core materials from loss and deterioration. To improve the stability of cinnamaldehyde (CAL), different microcapsule wall systems are fabricated by spray-drying, and then characterized by experimental methods to determine the most suitable wall materials. Surface morphology, encapsulation efficiency, effective loading capacity, as well as moisture absorption property are evaluated, and the results suggest that a three-matrix system of methyl cellulose (MC)/sodium alginate (SA)/MC or MC/carboxymethyl chitosan (CMC)/SA wall formulation is more suitable for CAL microencapsulation. Moreover, a novel quantitative method is also proposed to verify the most stable wall material microencapsulation. The quantitative results show that the highest activation energy (53.00 ± 2.24 kJ/mol) is observed for the MC/CMC/SA-encapsulated CAL microcapsule. Taken together, the results suggest that MC/CMC/SA wall formulation shows excellent barrier properties and is superior to other wall materials in preventing microencapsulated CAL deterioration. This study will be efficient in designing an ideal capsule for CAL microencapsulation.     

One‐step facile process to obtain insoluble polysaccharides fibrous mats from electrospinning of water‐soluble PMDA/cyclodextrin polymer

Herein, we used an electrospinning process to develop nanofibers based on poly‐cyclodextrin. This article describes a simple and effective method to produce fibers of a water‐soluble hyperbranched polymer based on β‐CD and pyromellitic dianhydride via electrospinning. The obtained fibers were made insoluble in water with a simple thermal crosslinking without the use of further reactive or solvent. After 24 h of dipping in distilled water or phosphate buffer solution morphology and size of fibers remain unaltered as observed in scanning electron microscopy. The crosslinking mechanism was studied with thermogravimetric analysis, attenuated total reflectance–Fourier infrared spectroscopy, and elemental analysis and a reaction mechanism is proposed. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46490.     

Environmentally friendly synthesis and photopolymerization of acrylated methyl ricinoleate for biomedical applications

In this study, we aimed to develop an efficient synthesis and photopolymerization of acrylated methyl ricinoleate (AMR) for biomedical applications. During the first step of the synthesis, methyl ricinoleate (MR) and boric acid were esterified via azeotropic distillation in toluene. Afterward, MR–boric acid ester was acrylated with acrylic acid at 165 °C via a boric acid ester acidolysis reaction. The bulk photopolymerization of AMR was performed in the presence of the photoinitiator 2,2-dimethoxy-2-phenyl acetophenone (DMPA) under 365 nm UV irradiation. Even with the use of 0.4% DMPA, a 35% monomer conversion was achieved within 30 min. Moreover, AMR, the plant-oil-based monomer, was also copolymerized with N-isopropyl acrylamide to obtain thermoresponsive hydrogels on the glass surface for biomedical applications. The synthesized materials were characterized by Fourier transform infrared (FTIR) spectroscopy, ¹H-NMR spectroscopy, and thermal characterization via thermogravimetric analysis (TGA) and differential scanning calorimetry techniques. The surfaces were characterized by FTIR and Energy Dispersive X-ray (EDS) spectroscopy. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47969.     

Rheology,injectability, and bioactivity of bioactive glass containing chitosan/gelatin,nano pastes

Bioactive pastes containing bioactive sol–gel derived glass (BG) and various amounts of chitosan (Cn) and gelatin (Gel) were prepared in this study. To be exact, three pastes were prepared by mixing 25 parts by weight of glass powder with (a) 100 parts by weight of a 3 wt% acetic acid-based chitosan solution, (b) 100 parts by weight of a 3 wt% water-based gelatin solution, and (c) 100 parts by weight of a solution containing equal amounts of the above-mentioned solutions. The bioactivity of the composite samples was evaluated by the immersion of the prepared pastes into the simulated body fluid (SBF) solution. The samples were also analyzed by X-ray diffractometry (XRD), Brunauer–Emmett–Teller (BET), scanning electron microscope (SEM), Fourier transform infrared (FTIR), and atomic absorption spectroscopy (AAS). The results indicated better apatite formation capacity on the glass-/chitosan-/gelatin-injected paste after 14 days. Furthermore, unlike the chitosan containing paste, the gelatin-containing sample was injectable and displayed viscoelastic behavior as determined by conducting the rheology test in oscillation mode. In addition, while chitosan made the paste more viscous, it improved the washout resistance when compared to the gelatin-containing sample. The experimental results also indicate the formation of spherical calcites in the pastes prior to immersion into the SBF solution.     

Effects of GPTMS concentration and powder to liquid ratio on the flowability and biodegradation behaviors of 45S5 bioglass/tragacanth bioactive composite pastes

Injectable composite pastes were prepared using melt-derived 45S5 bioactive glass and tragacanth crosslinked by (3-glycidyloxypropyl)trimethoxysilane (GPTMS). The effect of powder to liquid ratio (P:L = 1.0:2.0–1.0:2.5) and GPTMS/tragacanth ratio (0.0–1.5) on the injectability, swelling behavior, rheology, bioactivity, and cellular behavior of the pastes was investigated. Based on the results, the apparent stability and consistency of the pastes increased upon crosslinking by GPTMS. Due to the increased interactions between tragacanth and glass, a hysteresis loop with larger area was formed in the presence of GPTMS. With increase of GPTMS:tragacanth ratio from 0 to 1.5, the swelling percent dropped from 24.65 to 16.25% after 24 h and the degradation percent also went down from 27.89 to 9.11% after 21 days in the simulated body fluid. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay showed a drop in the optical density of MG63 osteoblasts up to 30.07% after exposure to the GPTMS-crosslinked composite pastes for 3 days. However, the number of viable cells gradually increased in the presence of the pastes and the cell morphology remained unchanged over time. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47604.     

Bioprinting a cell-laden matrix for bone regeneration: A focused review

Although many efforts have been made to regenerate the bone lesions, existing challenges can be mitigated through the development of tissue engineering scaffolds. However, the weak control on the microstructure of constructs, limitation in preparation of patient-specific and multilayered scaffolds, restriction in the fabrication of cell-laden matrixes, and challenges in preserving the drug/growth factors' efficacy in conventional methods have led to the development of bioprinting technology for regeneration of bone defects. So in this review, conventional 3D printers are classified, then the priority of the different types of bioprinting technologies for the preparation of the cell/growth factor-laden matrixes are focused. Besides, the bio-ink compositions, including polymeric/hybrid hydrogels and cell-based bio-inks are classified according to fundamental and recent studies. Herein, different effective parameters, such as viscosity, rheological properties, cross-linking methods, biodegradation biocompatibility, are considered. Finally, different types of cells and growth factors that can encapsulate in the bio-inks to promote bone repair are discussed, and both in vitro and in vivo achievement are considered. This review provides current and future perspectives of cell-laden bioprinting technologies. The restrictions and challenges are identified, and proper strategies for the development of cell-laden matrixes and high-performance printable bio-inks are proposed.     

Chitosan/silk fibroin composite scaffolds for wound dressing

Three‐dimensional (3D) chitosan/silk fibroin (CS/SF) porous composite scaffolds have been prepared by simply coating a thin layer of CS onto spunlaced SF scaffolds via hydrogen‐bonding assembly technique, and they were characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), X‐ray diffraction (XRD), and mechanical property measurements. The results show that porous scaffolds have a pore diameter around 50–200 μm, and improved mechanical property compared with SF, resulting from strong intermolecular hydrogen bonding interactions between CS and SF, together with the maintained β‐sheet structure of SF. The medical and biological properties of the composite scaffolds were further evaluated. The results demonstrate that they possess good biocompatibility and a broad spectrum of antimicrobial properties. The in vivo animal experiments show that the composite scaffolds promote skin regeneration of rats without any teratogenic effect and inflection, thus they are very promising in the application of wound dressings. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42503.     

PBAT/TPS-nanowhiskers blends preparation and application as food packaging

About 85–90% of the market for new materials in biodegradable packaging is served by various blends and composites containing starch in some portion. In an attempt to satisfy the increasing consumer demand, innovative materials are being developed. This includes the concept of active packaging, which, in addition to protecting, interacts with the packaged product. In this context, flexible films have been prepared from blends of poly(butylene adipate-co-terephthalate), thermoplastic starch (TPS), and cellulose nanowhiskers (CNW) at different concentrations (0–3.0 wt %) and with distinct compatibilizing agents (glycerol, stearic acid, and citric acid) by flat extrusion. Palm oil was packaged in the films, and was stored under accelerated oxidation conditions as a model system. The films were also used for packing lettuce. The TPS increased the rate of water vapor permeability of the blends. The micrographs showed the films with very porous surface as a function of the CNW concentration. In addition to the antimicrobial action pronounced within 10 days (fungi—molds and yeasts; bacteria—mesophilic and psychrotrophic), the film showed a prooxidant action, indicating its suitability for fruit and vegetable packaging. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47699.     

Analysis of void shape and size in the collector plate and polycaprolactone molecular weight on electrospun scaffold pore size

Many variations in the electrospinning process have emerged to control pore size needed in tissue scaffolds including introducing voids in the collector plate. However, the effect of different shapes and sizes of voids on fiber and pore sizes is not well understood. In this study, we evaluated the effect of void size and shapes in the collector plate on polycaprolactone (PCL) fiber size and pore size. First, we performed experiments using three different sizes of circular voids (0.9, 1.4, and 1.9 cm). Also, we evaluated the effect of triangular and rectangular voids. Further, changes in the electrical field within the voids were evaluated using computational fluid dynamic software COMSOL. Fibers using mixtures of PCL (high, medium, and low molecular weight) formed using void collector plate and performed degradation characteristics for 30 days in physiological conditions (37°C and 7.4 pH). These results showed that the size and the morphology of fibers are not affected by the geometrical patterns of the voids. However, fiber alignment is affected by the void shape due to favorable rearrangement in the electrical field. Fibers can be formed by mixing PCL of different molecular weight, and degradation of PCL fiber was accelerated by the mixture with low molecular weight. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Natural resources derived biocomposites as potential carriers of green pesticides in agricultural field: Designing and fabrication of a pot-like device

Hemp fibers (HF) are used as filler in pectin to produce biocomposites. To improve the compatibility of the filler with the polymeric matrix, HF are treated through mechanochemically assisted alkaline attack. The effect of the treatment time on the morphology of HF is investigated through atomic force microscopy and infrared spectroscopy. Cinnamic acid, a green pesticide, is added to the composites in order to test the capability of such materials to act as potential devices in the agricultural field. Analysis of thermal, mechanical, barrier properties and surface energy are evaluated on biocomposites and compared either to unfilled pectin or to composites filled with untreated HF. The release of cinnamic acid is evaluated and found to be dependent on the fibers' treatment time. The design and the fabrication of a pot prototype is also reported. The manufacture appears promising as green functional container for plants to be implanted in the ground.     

Silk fibroin membranes with self-assembled globular structures for controlled drug release

In this paper, we have evaluated the incorporation of a drug model and its release from silk fibroin (SF) membranes, analyzing the morphological, chemical, barrier, and biological properties. SF self-assembled into stable globular structures, encapsulating the drug, when diclofenac sodium (DS) was incorporated into SF solution prior to membranes preparation. The membranes showed biostatic action and prevented microorganism permeation. Kinetic studies indicate that DS was released in 120 min, with Fickian diffusion as the main mechanism of release. Results of this paper emphasize the potential of SF in wound healing, with good barrier and biological properties. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48763.     

Dual crosslinked carboxymethyl sago pulp/pectin hydrogel beads as potential carrier for colon‐targeted drug delivery

Carboxymethyl sago pulp (CMSP)/pectin hydrogel beads were synthesized by calcium crosslinking and further crosslinked by electron beam irradiation to form drug carrier for colon‐targeted drug. Sphere‐shaped CMSP/pectin 15%/5% hydrogel beads is able to stay intact for 24 h in swelling medium at pH 7.4. It shows pH‐sensitive behavior as the swelling degree increases as pH increases. Fourier transform infrared spectroscopy analysis confirmed the absence of chemical interaction between hydrogel beads and diclofenac sodium. Differential scanning calorimetric and X‐ray diffraction studies indicate the amorphous nature of entrapped diclofenac sodium. The drug encapsulation efficiency is up to about 50%. Less than 9% of drug has been released at pH 1.2 and the hydrogel beads sustain the drug release at pH 7.4 over 30 h. This shows the potential of CMSP/pectin hydrogel beads as carrier for colon‐targeted drug. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43416.     

Synthesis and characterization of star‐shaped PLLA with sorbitol as core and its microspheres application in controlled drug release

The purpose of this study was to investigate the suitability of a six‐arm star‐shaped poly(l ‐lactide)s (s‐PLLA) as controlled drug carriers for hydrophobic drug molecules. First, s‐PLLA was synthesized by ring‐opening polymerization of l ‐lactide using sorbitol as initiator and stannous octoate as catalyst. The structure and molecular weight (M_w) of s‐PLLA was characterized with ¹H NMR, ¹³C NMR, and GPC. Second, rifampicin (RIF) used as a model drug was encapsulated within the microspheres of s‐PLLA via oil‐in‐water emulsion/solvent evaporation technique. The morphology, drug encapsulation efficiency (EE), and in vitro release behavior of the prepared microspheres were studied in details. Results indicated that the average diameters of s‐PLLA microspheres can be controlled between 8 and 20 µm by varying the copolymer's concentration or M_w . The EE of RIF was mainly determined by the concentration of s‐PLLA. The in vitro study showed that the burst release behavior can be depressed by increasing the M_w of the s‐PLLA. Present work suggests that the synthesized s‐PLLA could be used as a new material for drug delivery. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42213.     

Sustained release of CIP from TiO2-PVDF/starch nanocomposite mats with potential application in wound dressing

Electrospinning is an economical and alluring method to fabricate wound dressing mats from a variety of natural and synthetic materials. In this study, polyvinylidene fluoride (PVDF) and starch composite mats containing ciprofloxacin (CIP) loaded on titanium dioxide nanoparticles (TiO₂) were prepared. Fourier Transform Infrared spectra of CIP, synthesized TiO₂ NPs, TiO₂/CIP, and PVDF/starch composite mats are analyzed. Scanning electron microscopy images revealed that the fiber diameter of PVDF nanofibers thickens by increasing starch, which varies between 180 nm and 550 nm. Strain at break of PVDF, starch, PVDF/starch (2:1 w:w; P2S1), PVDF/starch (1:1 w:w; P1S1), PVDF/starch (1:2 w:w; P1S2), and nanofibers were 103 ± 11, 3 ± 0.6, 27 ± 4, 52 ± 5.2, 7.7 ± 1%, respectively. Based on strain at break and young modulus, P2S1 was selected as a suitable candidate for wound dressing to which load TiO₂/CIP as a bioactive agent. The release rate of CIP showed that about 40% of the drug is released in the first 2 days. Furthermore, the antibacterial activity of dressings was investigated using Escherichia coli and Staphylococcus aureus microorganisms and zones of clearance were obvious around the specimen on the agar plate. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48916.