hUC-MSCs lyophilized powder loaded polysaccharide ulvan driven functional hydrogel for chronic diabetic wound healing.

In this study, we used the polysaccharide ulvan from the green macroalgae Ulva fenestrata to prepare the hydrogel for chronic diabetic wound healing. A natural polysaccharide-based hydrogel matrix (UC-DPA-Ag hydrogel) was prepared using ulvan dialdehyde, chitosan, dopamine (DPA) and silver nanoparticles (Ag NPs). Human umbilical cord mesenchymal stem cell lyophilized powder (hUC-MSCs) was loaded into the hydrogel to develop a novel chronic diabetic wound healing material (UC-DPA-Ag@hUC-MSCs). The resulting hydrogel features adequate mechanical properties, swelling capability, adhesiveness, antioxidant, antibacterial ability, and promoting cell proliferation and migration. In vivo wound healing in type II diabetic mellitus mouse wound model showed that hUC-MSCs loaded UC-DPA-Ag hydrogel could accelerate wound healing effectively. This advanced hydrogel provides a facile and effective way for diabetic chronic wound management. Furthermore, it offers a new route for the utilizing Ulva as a valuable biomaterial for the global and large-scale production of valued added biomaterials.

Biomimetic Colorants and Coatings Designed with Cephalopod-Inspired Nanocomposites.

Brilliant and dynamic colors in nature have stimulated the design of dyes and pigments with broad applications ranging from electronic displays to apparel. Inspired by the nanostructured pigment granules present in cephalopod chromatophore organs, we describe the design and fabrication of biohybrid colorants containing the cephalopod-specific pigment, xanthommatin (Xa), encased within silica-based nanostructures. We employed a biomimetic approach to encapsulate Xa with amine-terminated polyamidoamine (PAMAM) dendrimer templates, which helped stabilize the pigment during encapsulation. Depending on the concentration of Xa used in the reaction, the resultant biohybrid nanomaterials generated a range of neutral colors of differing hues. When applied as coatings, these colorants can be triggered to change color from yellow/gold to red in the presence of a chemical reducing agent, as we leverage the natural redox-dependent color change of Xa. Altogether, these capabilities demonstrated the ability to process biochromes like Xa as nanomaterials that can be applied as coatings with a tunable and dynamic range.

A filtration-assisted approach to enhance optical detection of analytes and its application in food matrices.

Analysis of target analytes in food and environmental samples often required sophisticated instrumentation, which restrains the accessibility and portability of the analysis. Herein, we developed an instrument-free approach for rapid quantification of target analytes. The reported filtration-assisted approach enables image analysis of aggregates formed via interaction between analytes and silver nanoparticles (AgNPs). Two model analytes were chosen for aggregating AgNPs, potassium phosphate for neutralizing the charges and a di-thiol molecule (2,2'-(ethylenedioxy) diethanethiol (EDT)) for cross-linking. The mixtures of AgNPs and analytes were filtered onto filter membranes and analyzed using grey color intensity analysis. Based on the AgNPs-EDT platform, we demonstrated the detection of 1 µg/mL acrylamide in instant coffee and biscuit matrices was achievable. The filtration-assisted method provides a simple, fast and inexpensive approach for optical detection and quantification of analytes in food matrices.

General method for emulsion polymerization to yield functional terpolymers.

Copolymerization methods are used to impart specific, desired functional properties (e.g. mechanical or bioactive) to a material for targeted applications in biomedicine, food and agriculture, consumer products, advanced manufacturing, and more. Many polymerization methods exist to achieve tailored copolymer architectures. Of them, emulsion polymerization offers unique and industrially convenient features that make for easily scalable processes because the synthesis occurs in water and the latexes usually do not need further purification. Because of the breadth of copolymer architectures and thus wide range of potential applications for latexes produced by emulsion polymerization, there is great value in defining general methods for emulsion polymerizations to yield copolymers, including routes for synthesis of functional monomer building blocks, to permit consistency and optimization of these processes. Herein we present a general emulsion polymerization method for synthesis of a copolymer consisting of three functional monomers, suitable for adaptation to alternate base chemistries, curing chemistries, and functional ligands. This protocol includes the synthesis of the functional monomers glycidyl methacrylate-iminodiacetic acid (GMA-IDA) and 4-benzolylphneyl methacrylate (BPM).•Our synthesized copolymer includes a glycidyl methacrylate (GMA) monomer functionalized with a metal-chelating iminodiacetic acid (IDA) ligand, a UV-curable monomer, 4-benzoylphenyl methacrylate (BPM), and an inert hydrophobic monomer, n­butyl acrylate (BA).•The presented synthesis route demonstrates a general polymerization method that can be modified to copolymerize alternative functional monomers to create multi-functional polymers.

Fabrication of green poly(vinyl alcohol) nanofibers using natural deep eutectic solvent for fast-dissolving drug delivery.

Fast-dissolving drug delivery systems are essential to drug delivery owing to the enhanced drug solubility, controlled drug concentration, target and rapid drug delivery. In this study, we developed fast-dissolving drug delivery systems using honey and acetylsalicylic acid-embedded poly(vinyl alcohol) (PVA) nanofibers based on natural deep eutectic solvent (DES). The efficacy of our fast-dissolving drug delivery system was tested by incorporating honey and acetylsalicylic acid in the PVA nanofibers. Firstly, the morphology and structure of the functional PVA-DES nanofibers (PVA-DES-honey and PVA-DES-ASA) were observed and analyzed, which proved the successful preparation of functional PVA-DES nanofibers. NIH/3T3 and HepG2 cells incubated on the nanofiber had more than 90% of cell viability, suggesting our materials were biocompatible and non-toxic. The nanofiber materials dissolved rapidly in artificial saliva solutions, suggesting potential use of our materials for fast dissolving drug delivery in oral cavities. The honey incorporated PVA nanofiber (PVA-DES-honey) showed a total bacterial reduction of 37.0% and 37.9% against E. coli and S. aureus, respectively, after 6 hour incubation in bacterial cultures. Furthermore, in vivo study proved that the PVA-DES-honey nanofibers accelerated the wound healing process, and they improved the wound healing rate on rat skin to 85.2% after 6 days of surgery, when compared to the control PVA (68.2%) and PVA-DES (76.3%) nanofibers. Overall, the nanofiber materials reported in our study showed potential as a green and biocompatible fast-dissolving drug delivery system and can be used for pharmaceutical fields, such as antibacterial wound dressing and oral ulcer stickers.

Multi-phase detection of antioxidants using surface-enhanced Raman spectroscopy with a gold nanoparticle-coated fiber.

The development of a method for multi-phase detection of antioxidants using surface-enhanced Raman spectroscopy (SERS) with a gold nanoparticle (AuNP)-coated fiber as a substrate is described. The AuNP-coated fiber was directly inserted into a multi-phase system containing model analytes of ascorbic acid, ascorbyl palmitate, and α-tocopherol, representing hydrophilic, amphiphilic, and lipophilic antioxidants, respectively. The AuNP-coated fiber enabled simultaneous detection of antioxidants present within the aqueous, interfacial, and organic phases of the multi-phase system. An oil-in-water emulsion was used as a model multi-phase system, where the antioxidant profiles of the three model analytes were successfully characterized. This method enables rapid, simultaneous, and non-destructive analysis of multiple antioxidants in complex multi-phase systems.

In situ assembly of well-dispersed Ag nanoparticles on the surface of polylactic acid-Au@polydopamine nanofibers for antimicrobial applications.

Nanofibrous membranes which exhibit bacteriostatic functions are a good strategy to prevent microorganisms from adhering to the surface of biomaterials. Here, we report the synthesis of such a nanofibrous membrane which can be applied to biological coatings to reduce bacteriostatic functionality. Ascorbic acid was utilized to reduced chloroauric acid to gold nanoparticles (AuNPs). Dopamine was then polymerized upon AuNP surfaces by ultrasound-assistance, to synthesize core-shell structured polydopamine-coated AuNPs (Au@PDA NPs). The Au@PDA NPs were then mixed with polylactic acid (PLA) for electrospinning into cylindrical nanofibers (136.6 nm diameter). PLA-Au@PDA nanofibrous membranes were finally immersed in silver nitrate for in situ reduction into a silver nanoparticle (AgNP) coating to yield PLA-Au@PDA@Ag nanofibers. The PLA-Au@PDA@Ag nanofibers were characterized based on field emission scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and contact angle analyses. The antibacterial properties of the PLA-Au@PDA@Ag nanofibers were examined based on the optical density absorbance of bacterial cell suspensions, traditional colony plate counts, zone inhibition analyses, and field-emission scanning electron microscopy. Escherichia coli and Staphylococcus aureaus respectively served as Gram negative and positive bacterial models of industrial relevance. The data conclusively illustrates the antimicrobial and biomedical applications of PLA-Au@PDA@Ag nanofibers.

Performance of photo-curable metal-chelating active packaging coating in complex food matrices.

Many packaged goods undergo transition metal-catalyzed oxidative spoilage. Recently, a nonmigratory photocurable metal-chelating coating was developed as an innovative active packaging approach to control oxidation of foods. In the present study, we investigate the influence of competing ions and increasing viscosity on the iron-chelating capacity and antioxidant efficacy of this coating in a model complex food system. The addition of calcium and magnesium causes a decrease in iron chelating capacity; however, 61% chelating capacity of materials was retained when 0.8 M sodium was present. Materials retained iron-chelating capacity even in solutions of 2700 cP, similar to the viscosity of salad dressing. Additionally, metal-chelating films significantly delayed transition metal-catalyzed ascorbic acid degradation, even in the presence of competing ions and at increased viscosity. These results suggest that metal-chelating active packaging coatings may present a new technological approach to addressing consumer demands for reduced additive use while controlling food spoilage and waste.

Facile Preparation of Epoxide-Functionalized Surfaces via Photocurable Copolymer Coatings and Subsequent Immobilization of Iminodiacetic Acids.

Herein, we report a simple coat/cure preparation of epoxide-functionalized surfaces using a photocurable copolymer technology. The photocurable copolymer, poly(glycidyl methacrylate- co-butyl acrylate- co-4-benzoylphenyl methacrylate) (GBB), was synthesized by single electron transfer-living radical polymerization (SET-LRP). The epoxide content in the copolymer was tuned by controlling the content of glycidyl methacrylate. Three copolymers, GBB(1), GBB(2), and GBB(3), with epoxide contents of 22, 63, and 91 mol %, respectively, were cast onto polypropylene films and photocured by UV-light exposure. Subsequently, iminodiacetic acids (IDA) were immobilized onto the GBB-coated materials via a ring-opening reaction. The IDA-functionalized coatings GBB(1)-IDA, GBB(2)-IDA, and GBB(3)-IDA presented IDA contents of 1.47 ± 0.08, 18.67 ± 1.46, and 49.05 ± 2.88 nmol/cm2, respectively, which increased as the epoxide content increased. The IDA-functionalized GBB coatings exhibited metal chelating capability toward transition metal ions (e.g., iron and copper). The reported photocurable copolymer technology offers a facile and tunable preparation of epoxide-functionalized surfaces, with potential extended applications in biopatterning, active packaging, and nanotechnology.

Photocurable coatings prepared by emulsion polymerization present chelating properties.

Herein, we present a method to synthesize a photocurable metal chelating copolymer coating via emulsion polymerization to enable a facile coat/cure preparation of metal chelating materials. The copolymer coating was a poly(n-butyl acrylate) based polymer (79 mol %) synthesized by emulsion polymerization, with iminodiacetic acid (2 mol %) and benzophenone moieties (19 mol %) to impart metal chelating and photocrosslinking properties, respectively. The copolymer was applied onto polypropylene films and was photocured (365 nm, 225 mW/cm2, 180 s) to produce metal chelating film. The resulting metal chelating film had activity towards Fe3+ by chelating 10.9 ± 1.9 nmol/cm2, 47.9 ± 5.3 nmol/cm2, and 156.0 ± 13.8 nmol/cm2 of Fe3+ at pH 3.0, pH 4.0, and pH 5.0, respectively. The metal chelating film controlled transition metal induced ascorbic acid degradation by extending half-life of ascorbic acid degradation from 6 days to 20 days at pH 3.0, and from 3 days to 6 days at pH 5.0, demonstrating its potential as an antioxidant active packaging material. Despite the introduction of polar iminodiacetic acid chelating moieties, the poly(n-butyl acrylate) based coatings retained low surface energies (24.0 mN/m) necessary to mitigate fouling and enable product release in packaging applications. This work overcomes a major knowledge gap in the area of functional coatings, by demonstrating a method by which critical properties such as control of surface energy, retention of mechanical properties, and scalability are integrated into the structure of a functional coating. The photocurable polymer coatings as reported here enable scalable production of active materials with metal chelating functionality, with applications in water treatment, trace metal detection, protein purification, and active packaging.

Photo-Curable Metal-Chelating Coatings Offer a Scalable Approach to Production of Antioxidant Active Packaging.

Synthetic metal chelators (for example, ethylenediaminetetraacetic acid, EDTA) are widely used as additives to control trace transition metal induced oxidation in consumer products. To enable removal of synthetic chelators in response to increasing consumer demand for clean label products, metal-chelating active food packaging technologies have been developed with demonstrated antioxidant efficacy in simulated food systems. However, prior work in fabrication of metal-chelating materials leveraged batch chemical reactions to tether metal-chelating ligands, a process with limited industrial translatability for large-scale fabrication. To improve the industrial translatability, we have designed a 2-step laminated photo-grafting process to introduce metal chelating functionality onto common polymeric packaging materials. Iminodiacetic acid (IDA) functionalized materials were fabricated by photo-grafting poly(acrylic acid) onto polypropylene (PP) films, followed by a second photo-grafting process to graft-polymerize an IDA functionalized vinyl monomer (GMA-IDA). The photo-grafting was conducted under atmospheric conditions and was completed in 2 min. The resulting IDA functionalized metal-chelating material was able to chelate iron and copper, and showed antioxidant efficacy against ascorbic acid degradation, supporting its potential to be used synergistically with natural antioxidants for preservation of food and beverage products. The 2-step photo-grafting process improves the throughput of active packaging coatings, enabling potential roll-to-roll fabrication of metal-chelating active packaging materials for antioxidant food packaging applications. PRACTICAL APPLICATION: To address consumer and retail demands for "clean label" foods and beverages without a corresponding loss in product quality and shelf life, producers are seeking next generation technologies such as active packaging. In this work, we will report the synthesis of metal-chelating active packaging films, which enable removal of the synthetic additive, ethylenediamine tetraacetic acid. The new synthesis technique improves the throughput of metal-chelating active packaging coatings, enabling potential roll-to-roll fabrication of the materials for antioxidant food packaging applications.

Synthesis of Iminodiacetate Functionalized Polypropylene Films and Their Efficacy as Antioxidant Active-Packaging Materials.

The introduction of metal-chelating ligands to the food-contact surface of packaging materials may enable the removal of synthetic chelators (e.g., ethylenediamine tetra-acetic acid (EDTA)) from food products. In this study, the metal-chelating ligand iminodiacetate (IDA) was covalently grafted onto polypropylene surfaces to produce metal-chelating active-packaging films. The resulting films were able to chelate 138.1 ± 26 and 210.0 ± 28 nmol/cm(2) Fe(3+) and Cu(2+) ions, respectively, under acidic conditions (pH 3.0). The films demonstrated potent antioxidant efficacy in two model food systems. In an emulsified-oil system, the chelating materials extended the lag phase of both lipid hydroperoxide and hexanal formation from 5 to 25 days and were as effective as EDTA. The degradation half-life of ascorbic acid in an aqueous solution was extended from 5 to 14 days. This work demonstrates the potential application of surface-grafted chelating IDA ligands as effective antioxidant active food-packaging materials.