Bioremediation of Copper-Ions by Polymer Encapsulated and Immobilized Micrococcus Luteus.

Bioremediation of copper (Cu2+ ) with immobilized Micrococcus luteus in polymer matrices has been broadly studied for a wide range of applications including wastewater treatment. Herein, the bioremediation efficiency based on modified immobilization techniques and by the addition of Cu2+ is investigated. Porous composite nonwovens with living M. luteus (living polymer composites) are prepared by encapsulation of the bacterial cells in poly(vinyl alcohol) (PVA) microparticles (M. luteus/PVA microparticles) produced by spray drying method. The M. luteus/PVA microparticles are chemically cross-linked. The hydrogel microparticles with encapsulated M. luteus are embedded in a nonwoven of poly (lactic acid) (PLA) electrospun short fibers provided by wet-laid method. Two different models of composite nonwovens are reported, in which the place position of the hydrogel PVA microparticles with encapsulated M. luteus and PLA nonwoven can affect the bioremediation process.

Bacillus subtilis in PVA Microparticles for Treating Open Wounds.

Open wound dressings should provide a moist environment, protect the wound from bacterial contamination, and shield it from further damage. These requirements, however, are hard to accomplish since such wounds are colonized by pathogenic bacteria, including resistant species such as methicillin-resistant Staphylococcus aureus (MRSA). A new approach for treating open wounds that is based on sticky and dissolvable polyvinyl alcohol (PVA) microparticles containing live Bacillus subtilis (B. subtilis) is described. Microparticles, fabricated by the spray-drying technique, were administered directly to an open wound while B. subtilis continuously produced and secreted antimicrobial molecules. B. subtilis in PVA microparticles demonstrated remarkable antibacterial activity against MRSA and S. aureus. In in vivo experiments, both B. subtilis and empty PVA microparticles were effective in decreasing healing time; however, B. subtilis microparticles were more effective during the first week. There was no evidence of skin irritation, infection, or other adverse effects during the 15 day postoperative observation period. This concept of combining live secreting bacteria within a supportive delivery system shows great promise as a therapeutic agent for open wounds and other infectious skin disorders.

Poly(Vinyl Alcohol)-Hydrogel Microparticles with Soft Barrier Shell for the Encapsulation of Micrococcus luteus.

The encapsulation of bacteria in polymers results in hybrid materials that are essential for the long-term biological activity of bacteria and formulations in practical applications. Here, the problem of bacterial escape and the exchange of metabolism products from hydrogel microparticles within an aqueous environment are addressed. Bacteria are encapsulated in chemically cross-linked poly(vinyl alcohol) (PVA) hydrogel-microparticles followed by their encapsulation in a pH-responsive and soft antibacterial shell of poly(N,N-diethylamino ethyl methacrylate) (PDEAEMA). This polymer shell acts selectively with regards to the mass transport in and out of the microparticle core and is affected by environmental parameters, such as pH and antibacterial effect. The pH-responsive PDEAEMA shell forms an open porous structure that accelerates nutrient transfer into the PVA core containing living Micrococcus luteus (M. luteus). Results show that the antibacterial effect of PDEAEMA retards the escape of bacteria up to 35 days when the shell is open. Additionally, the permeation of a small molecule into the gel, for example, methylene blue dye through the core/open-shell structure, certifies a flexible barrier for mass transport, which is required in the long term for the biological activity of encapsulated M. luteus.

Ultralight, Structurally Stable Electrospun Sponges with Tailored Hydrophilicity as a Novel Material Platform.

Sponges based on short electrospun fibers have received significant attention due to their ultrahigh porosity, lightweight, and multifunctional characteristics. In particular, polyimide (PI) sponges have been researched due to their exceptional mechanical properties and thermal stability. Nevertheless, a number of sponges, including PI, are usually hydrophobic and synthesized in toxic, nonwater solvents (e.g., 1,4-dioxane). Conversely, hydrophilic sponges disintegrate upon contact with water. Here, we suggest a new strategy to fabricate PI sponges in water by introducing a suitable surfactant, sodium dodecylbenzenesulfonate (SDBS) (sPI sponges). With less than 1 wt % of SDBS with respect to PI short fibers, they can be homogeneously dispersed in water and mixed well with poly(amic acid) (PAA) solution. The synthesized sponge, depending on the concentration of SDBS, showed hydrophilic properties and substantial water uptake above 5000%. The hydrophilic properties of the sponges, which are not common, and the preparation from aqueous solution introduce new research opportunities. Such hydrophilic sponges are particularly special because they do not swell in contact with water, which makes them dimensionally stable. The methods presented here can serve as a milestone for the future development of various kinds of hydrophilic sponges applied for various applications, ranging from tissue engineering to oil/water separation.

High-Temperature Spray-Dried Polymer/Bacteria Microparticles for Electrospinning of Composite Nonwovens.

Living Micrococcus luteus (M. luteus) and Escherichia coli (E. coli) are encapsulated in poly(vinyl alcohol), poly(vinylpyrrolidone), hydroxypropyl cellulose, and gelatin by high-temperature spray drying. The challenge is the survival of the bacteria during the standard spray-drying process at temperatures of 150 °C (M. luteus) and 120 °C (E. coli). Raman imaging and transmission electron microscopy indicate encapsulated bacteria in hollow composite microparticles. The versatility of the spray-dried polymer bacteria microparticles is successfully proved by standard polymer solution-processing techniques such as electrospinning, even with harmful solvents, to water-insoluble polyacrylonitrile, polystyrene, poly(methyl methacrylate), and poly(vinyl butyrate) nanofiber nonwovens, which opens numerous new opportunities for novel applications.