Poly(3-hydroxybutyrate) Degradation by Bacillus infantis sp. Isolated from Soil and Identification of phaZ and bdhA Expressing PHB Depolymerase.

Poly(3-hydroxybutyrate) (PHB) is a biodegradable and biocompatible bioplastic. Effective PHB degradation in nutrient-poor environments is required for industrial and practical applications of PHB. To screen for PHB-degrading strains, PHB double-layer plates were prepared and three new Bacillus infantis species with PHB-degrading ability were isolated from the soil. In addition, phaZ and bdhA of all isolated B. infantis were confirmed using a Bacillus sp. universal primer set and established polymerase chain reaction conditions. To evaluate the effective PHB degradation ability under nutrient-deficient conditions, PHB film degradation was performed in mineral medium, resulting in a PHB degradation rate of 98.71% for B. infantis PD3, which was confirmed in 5 d. Physical changes in the degraded PHB films were analyzed. The decrease in molecular weight due to biodegradation was confirmed using gel permeation chromatography and surface erosion of the PHB film was observed using scanning electron microscopy. To the best of our knowledge, this is the first study on B. infantis showing its excellent PHB degradation ability and is expected to contribute to PHB commercialization and industrial composting.

Performance of wild, tailed, humidity-robust phage on a surface-scanning magnetoelastic biosensor for Salmonella Typhimurium detection.

A wild, tailed phage (TST) was compared with a genetically modified, filamentous phage (FST) for S. Typhimurium (ST) detection. When both phages were introduced into oppositely charged MUA and MUAM sensors, the RU values of TST showed an obvious increase on the MUAM sensor. The sensitivity of TST [54.78 ΔRU/(log PFU/mL)] was greater than that of FST [48.05 ΔRU/(log PFU/mL)]. The binding affinity (KD = 1.75 × 10-13 M) of TST on MUAM sensor was greater than that of FST. Both phages were specific to only ST, and TST exhibited a persistent binding capability at 50 % RH. When each phage-immobilized sensor was employed on chili pepper, the sensitivity [880.80 Hz/(log CFU/mL)] and detection limit (1.31 ± 0.27 log CFU/mL) of TST were significantly greater than those of FST. The orientation of TST on sensor promoted the uniform capture of bacteria and enhanced the reliable performance of a surface-scanning magnetoelastic biosensor.

Highly Transparent, Robust Hydrophobic, and Amphiphilic Organic-Inorganic Hybrid Coatings for Antifogging and Antibacterial Applications.

The control of surface wettability through a combination of surface roughness, chemical composition, and structural modification has attracted significant attention for antifogging and antibacterial applications. Herein, a two-step spin-coating method for amphiphilic organic-inorganic hybrid materials with incorporated transition metal ions is presented. The coating solution was prepared via photochemical thiol-ene click reaction between the mercapto functional group in trimethylolpropane tris(3-mercaptopropionate) and the vinyl functionalized silica precursor 3-(trimethoxysilyl)propyl methacrylate. In the first step of coating, a glass substrate was coated using a solution of metal nitrate hydrates and subsequently showed hydrophobic properties. As the second step, the spin-coated glass substrate was further coated with silica nanoparticles (SiO2 NPs) and polycaprolactone triol (PCT) suspension, where the contents of SiO2 NPs were fixed at 0.1 wt %, unless otherwise noted. The coated substrate exhibited hydrophilic properties. For comparison, the coating was also formulated with the SiO2 NPs/PCT suspension without SiO2 NPs and with 0.5 wt % SiO2 NPs as well as by adjusting different coating layer thicknesses. The surface morphology and chemical compositions of the obtained coating materials were analyzed by field emission scanning electron microscopy with energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. The transparency and static contact angle of coated samples were measured by UV-visible spectrophotometry and drop shape analysis, respectively. It was concluded that our novel hybrid coating materials exhibited excellent antibacterial and antifogging properties with extremely high scratch resistance and transparency.

Synergistic effects of gelatin and nanotopographical patterns on biomedical PCL patches for enhanced mechanical and adhesion properties.

Biomedical patches have been known as important biomaterial-based medical devices for the clinical treatment of tissue and organ diseases. Inspired by the extracellular matrix-like aligned nanotopographical pattern as well as the unique physical and biocompatible properties of gelatin, we developed strength-enhanced biomedical patches by coating gelatin onto the nanopatterned surface of polycaprolactone (PCL). The relative contributions of the nanotopographical pattern (physical factor) and gelatin coating (chemical factor) in enhancing the mechanical and adhesive properties of PCL were quantitatively investigated. The nanotopographical pattern increased the surface area of PCL, allowing more gelatin to be coated on its surface. The biomedical patch made from gelatin-coated nanopatterned PCL showed strong mechanical and adhesive properties (tensile strength: ~14.5 MPa; Young's modulus: ~60.2 MPa; and normal and shear adhesive forces: ~1.81 N/cm2 and ~352.3 kPa) as well as good biocompatibility. Although the nanotopographical pattern or gelatin coating alone could enhance these physical properties of PCL in both dry and wet environmental conditions, both factors in combination further strengthened the properties, indicating the importance of synergistic cues in driving the mechanical behavior of biomedical materials. This strength-enhanced biomedical patch will be especially useful for the treatment of tissues such as cartilage, tendon, and bone.

Hexadecyltrimethylammonium Bromide Surfactant-Supported Silica Material for the Effective Adsorption of Metanil Yellow Dye.

The adsorption behavior of an organic dye, metanil yellow (My), from water using micro-nano silica particles (MNSPs) was investigated. MCM-41-like (Mobil Composition of Matter No. 41) MNSPs were synthesized using tetraethoxy orthosilicate as a silica source and hexadecyltrimethylammonium bromide (CTAB) as a surfactant under basic conditions. Comparative studies were performed to assess the adsorption behaviors of the organic dye using the as-synthesized MCM-41 before the removal of CTAB and MCM-41, either after one, two, and three times of chemical etching or after calcination. My was adsorbed more effectively from water on the as-synthesized MCM-41 without the removal of the surfactant than on MCM-41 after the removal of the surfactant by chemical etching or calcination. In addition, MCM-41 after removing the surfactant by one-time chemical etching in the presence of hydrochloric acid also showed better adsorption of My from water than MCM-41 after removing the surfactant by further two and three times of chemical etching or calcination. For comparison, other kinds of dye molecules with different chemical structures such as methylene blue (Mb) and rhodamine B (Rb) were also used to check the possibility of adsorption of various dyes by the CTAB-supported MNSPs. To better understand the reason behind the adsorption phenomena, detailed studies on the kinetics and thermodynamics of adsorption of the MNSPs were performed. Excellent adsorption of My was observed at concentrations up to 100 mg L-1 at 25 °C, whereas the adsorption was lower at higher concentrations of the My dye. Furthermore, enhanced My dye adsorption was observed at higher concentrations by increasing the adsorption temperature. It can be concluded that the MNSPs exhibited efficient adsorption of My, when the MNSPs are used without the removal of the surfactant and any further modifications, suggesting that the surfactant played key roles in the effective adsorption of the anionic dye. The as-synthesized MCM-41 was, however, not a good adsorbent for cationic dyes such as Mb and Rb.