Extracellular DNA Provides Structural Integrity to a Micrococcus luteus Biofilm.

Force spectroscopy was used to show that extracellular DNA (eDNA) has a pre-eminent structural role in a biofilm. The adhesive behavior of extracellular polymeric substances to poly(ethylene terephthalate), a model hydrophobic surface, was measured in response to their degradation by hydrolytic enzymes known for their biofilm dispersion potential: DNaseI, protease, cellulase, and mannanase. Only treatment with DNaseI significantly decreased the adhesive force of the model bacterium Micrococcus luteus with the surface, and furthermore this treatment almost completely eliminated any components of the biofilm maintaining the adhesion, establishing a key structural role for eDNA.

Galactose-functionalized polyHIPE scaffolds for use in routine three dimensional culture of mammalian hepatocytes.

Three-dimensional (3D) cell culture is regarded as a more physiologically relevant method of growing cells in the laboratory compared to traditional monolayer cultures. Recently, the application of polystyrene-based scaffolds produced using polyHIPE technology (porous polymers derived from high internal phase emulsions) for routine 3D cell culture applications has generated very promising results in terms of improved replication of native cellular function in the laboratory. These materials, which are now available as commercial scaffolds, are superior to many other 3D cell substrates due to their high porosity, controllable morphology, and suitable mechanical strength. However, until now there have been no reports describing the surface-modification of these materials for enhanced cell adhesion and function. This study, therefore, describes the surface functionalization of these materials with galactose, a carbohydrate known to specifically bind to hepatocytes via the asialoglycoprotein receptor (ASGPR), to further improve hepatocyte adhesion and function when growing on the scaffold. We first modify a typical polystyrene-based polyHIPE to produce a cell culture scaffold carrying pendent activated-ester functionality. This was achieved via the incorporation of pentafluorophenyl acrylate (PFPA) into the initial styrene (STY) emulsion, which upon polymerization formed a polyHIPE with a porosity of 92% and an average void diameter of 33 µm. Histological analysis showed that this polyHIPE was a suitable 3D scaffold for hepatocyte cell culture. Galactose-functionalized scaffolds were then prepared by attaching 2'-aminoethyl-ß-D-galactopyranoside to this PFPA functionalized polyHIPE via displacement of the labile pentafluorophenyl group, to yield scaffolds with approximately ca. 7-9% surface carbohydrate. Experiments with primary rat hepatocytes showed that cellular albumin synthesis was greatly enhanced during the initial adhesion/settlement period of cells on the galactose-functionalized material, suggesting that the surface carbohydrates are accessible and selective to cells entering the scaffold. This porous polymer scaffold could, therefore, have important application as a 3D scaffold that offers enhanced hepatocyte adhesion and functionality.

Acrylic-acid-functionalized PolyHIPE scaffolds for use in 3D cell culture.

This study describes the development of a functional porous polymer for use as a scaffold to support 3D hepatocyte culture. A high internal phase emulsion (HIPE) is prepared containing the monomers styrene (STY), divinylbenzene (DVB), and 2-ethylhexyl acrylate (EHA) in the external oil phase and the monomer acrylic acid (Aa) in the internal aqueous phase. Upon thermal polymerization with azobisisobutyronitrile (AIBN), the resulting porous polymer (polyHIPE) is found to have an open-cell morphology and a porosity of 89%, both suitable characteristics for 3D cell scaffold applications. X-ray photo-electron spectroscopy reveals that the polyHIPE surface contained 7.5% carboxylic acid functionality, providing a useful substrate for subsequent surface modifications and bio-conjugations. Initial bio-compatibility assessments with human hepatocytes show that the acid functionality does not have any detrimental effect on cell adhesion. It is therefore believed that this material can be a useful precursor scaffold towards 3D substrates that offer tailored surface functionality for enhanced cell adhesion.

Covalent polyester colouration by in situ chromophore creation.

The permanent colouration of a polyester by straightforward azo coupling is disclosed. Uniquely, the chromophore is created only upon successful polymer modification with a non-coloured molecule (in situ colouration), which confirms successful polymer adaptation and ensures that coloured waste is not produced. The method of colouration, which may feasibly be applied for the coloration of a wide-range of step-growth polyesters, yielded a polymer capable of preventing indigo deposition onto a range of fabrics, offering potential use within advanced detergent formulations.

Microfiber release from real soiled consumer laundry and the impact of fabric care products and washing conditions.

Fiber release during domestic textile washing is a cause of marine microplastic pollution, but better understanding of the magnitude of the issue and role of fabric care products, appliances and washing cycles is needed. Soiled consumer wash loads from U.K. households were found to release a mean of 114 ± 66.8 ppm (mg microfiber per kg fabric) (n = 79) fibers during typical washing conditions and these were mainly composed of natural fibers. Microfiber release decreased with increasing wash load size and hence decreasing water to fabric ratio, with mean microfiber release from wash loads in the mass range 1.0-3.5 kg (n = 57) found to be 132.4 ± 68.6 ppm, significantly (p = 3.3 x 10-8) higher than the 66.3 ± 27.0 ppm of those in the 3.5-6.0 kg range (n = 22). In further tests with similar soiled consumer wash loads, moving to colder and quicker washing cycles (i.e. 15°C for 30 mins, as opposed to 40°C for 85 mins) significantly reduced microfiber generation by 30% (p = 0.036) and reduced whiteness loss by 42% (p = 0.000) through reduced dye transfer and soil re-deposition, compared to conventional 40°C cycles. In multicycle technical testing, detergent pods were selected for investigation and found to have no impact on microfiber release compared to washing in water alone. Fabric softeners were also found to have no direct impact on microfiber release in testing under both European and North American washing conditions. Extended testing of polyester fleece garments up to a 48-wash cycle history under European conditions found that microfiber release significantly reduced to a consistent low level of 28.7 ± 10.9 ppm from eight through 64 washes. Emerging North American High-Efficiency top-loading washing machines generated significantly lower microfiber release than traditional top-loading machines, likely due to their lower water fill volumes and hence lower water to fabric ratio, with a 69.7% reduction observed for polyester fleece (n = 32, p = 7.9 x 10-6) and 37.4% reduction for polyester T-shirt (n = 32, p = 0.0032). These results conclude that consumers can directly reduce the levels of microfibers generated per wash during domestic textile washing by using colder and quicker wash cycles, washing complete (but not overfilled) loads, and (in North America) converting to High-Efficiency washing machines. Moving to colder and quicker cycles will also indirectly reduce microfiber release by extending the lifetime of clothing, leading to fewer new garments being purchased and hence lower incidence of the high microfiber release occurring during the first few washes of a new item.