Dopamine/Silica Nanoparticle Assembled, Microscale Porous Structure for Versatile Superamphiphobic Coating

Artificial superamphiphobic surfaces, which could repel both water and low surface tension organic liquids, have been limited to particular kinds of materials or surfaces thus far. In this work, a kind of microscale porous coating was developed. Taking dopamine and hydrophilic fumed silica nanoparticles as initial building blocks, microscale porous coating was constructed <i>via</i> ice templation. Polydopamine bound silica nanoparticles together to form a porous structure network and rendered the coating to have potential for further postfunctionalization. After two-step CVD, the microscale porous coating changes from superhydrophilic to superamphiphobic, exhibiting super-repellency to droplets with surface tension of 73–23 mN/m. The influences of concentration of initial dopamine, hydrophilic fumed silica nanoparticles, and dry conditions on the formation of the porous structure have been studied to optimize the conditions. Coatings with different pore sizes and pore heights have been fabricated to discover the relationship between the structure parameters and the repellency of the porous coatings. Only with optimal pore size and pore height can the porous coating display superamphiphobicity. Compared with nanoscale, the microscale structure favors the achievement of superamphiphobicity. Given the outstanding adhesive ability of polydopamine, the superamphiphobic coatings have been successfully applied to various materials including artificial materials and natural materials

Thickening of the Immobilized Polymer Layer Using Trace Amount of Amine and Its Role in Promoting Gelation of Colloidal Nanocomposites

Immobilized polymer layers surrounding nanoparticles are proposed to be of essentially vital importance for the reinforcement of nanofiller to polymer matrices, but there is still a need to clarify its contribution to diverse rheological performance like colloidal stability and gelation. In this study, we find for the first time that introducing a trace amount of secondary/tertiary amine efficiently thickens the immobilized glassy layer in hydrophilic fumed silica (FS) filled polypropylene glycol (PPG) from 1.5 to 4.5 nm, which simultaneously promotes gelation of the liquid-like dispersion even containing extremely low contents of FS (<2 vol %). By coordinately using modulated differential scanning calorimetry and rheology methods, we find strong evidence that (1) the amine-promoted gelation is due to thickening and easy-percolation of the inner glassy layer converted from an outer uncrystallizable layer, and (2) the dispersion rheology could be well normalized within the framework of a two-phase model incorporating effective volume fraction of nanoparticles plus the glassy layers. We also highlight the importance of the surface chemistry of FS for adjusting the polymer immobilization and dispersion rheology

Study of Polyelectrolyte Complex Nanoparticles as Novel Templates for Biomimetic Mineralization

Needle-like water-soluble polyelectrolyte complex nanoparticles (PEC NPs), consisting of sodium carboxylmethyl cellulose (CMCNa) and poly­(methacryloxyethyl trimethyl ammonium chloride) (PDMC), were studied as novel templates for biomimetic mineralization. Barium acetate and sodium sulfate solutions were added simultaneously into CMCNa/PDMC polyelectrolyte complex (PEC) solutions as BaSO₄ precursors. Spherical BaSO₄ crystals with unique annual ring cross section were synthesized in different concentrations of PEC solution. Energy dispersive X-ray spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and thermogravimetric analysis (TGA) showed that these crystals were composed of ca. 90–95 wt % BaSO₄ and 5–10 wt % PEC NPs. Study of ionic strength effect on PEC mineralization revealed that the rigid needle-like structure of PEC is responsible for BaSO₄ morphology. In addition, the mineralization differences between CMCNa and CMCNa/PDMC PEC are discussed

Rarefaction curves.

<p>Based on A: nucleotide sequences; B: amino acid sequences. Cutoff values are selected as 1%, 3% and 10% for nucleotide sequences, and 1%, 3% and 5% for amino acid sequences.</p

Boundary Lubrication by Associative Mucin

Mucus lubricants are widely distributed in living organisms. Such lubricants consist of a gel structure constructed by associative mucin. However, limited tribological studies exist on associative mucin fluids. The present research is the first to investigate the frictional behavior of a typical intact vertebrate mucin (loach skin mucin), which can recover the gel structure of mucus via hydrophobic association under physiological conditions (5–10 mg/mL loach skin mucin dissolved in water). Both rough hydrophobic and hydrophilic polydimethylsiloxane (PDMS) rubber plates were used as friction substrates. Up to 10 mg/mL loach skin mucin dissolved in water led to a 10-fold reduction in boundary friction of the two substrates. The boundary-lubricating ability for hydrophilic PDMS decreased with rubbing time, whereas that for hydrophobic PDMS remained constant. The boundary-lubricating abilities of the mucin on hydrophobic PDMS and hydrophilic PDMS showed almost similar responses toward changing concentration or sodium dodecyl sulfate (SDS). The mucin fluids reduced boundary friction coefficients (μ) only at concentrations (<i>c</i>) in which intermucin associations were formed, with a relationship shown as μ ∼ <i>c</i>^–0.7. Destroying intermucin associations by SDS largely impaired the boundary-lubricating ability. Results reveal for the first time that intermolecular association of intact mucin in bulk solution largely enhances boundary lubrication, whereas tightly adsorbed layer plays a minor role in the lubrication. This study indicates that associated mucin should contribute considerably to the lubricating ability of biological mucus in vivo

The community composition in each station.

<p>The community composition in each station.</p

The difference of codon usage.

<p>The difference of codon usage.</p

Map of the ECS showing the locations of the sampling stations.

<p>Map of the ECS showing the locations of the sampling stations.</p

Image_2_A Virus Infecting Marine Photoheterotrophic Alphaproteobacteria (Citromicrobium spp.) Defines a New Lineage of ssDNA Viruses.TIF

<p>In recent metagenomic studies, single-stranded DNA (ssDNA) viruses that infect bacteria have been shown to be diverse and prevalent in the ocean; however, there are few isolates of marine ssDNA phages. Here, we report on a cultivated ssDNA phage (vB_Cib_ssDNA_P1) that infects Citromicrobium bathyomarinum RCC1878 (family Sphingomonadaceae), and other members of the genus. This is the first ssDNA phage reported to infect marine alphaproteobacteria, and represents a newly recognized lineage of the Microviridae infecting members of Sphingomonadaceae, the Amoyvirinae. The ∼26 nm diameter polyhedral capsid contains a 4,360 bp genome with 6 open reading frames (ORFs) and a 59.3% G+C content. ORF1 encodes the capsid protein and ORF3 encodes the replication initiator protein. The replication cycle is ∼5 h, followed by a burst releasing about 180 infectious particles. The closest relative of vB_Cib_ssDNA_P1 is a prophage within the genome of Novosphingobium tardaugens strain NBRC16725. Phylogenetic analysis indicates that the vB_Cib_ssDNA_P1 phage and two related prophages, as well as an environmental sequence, form a novel group within the Microviridae. Our results indicate that this is a previously unknown lineage of ssDNA viruses which also supplies a new model system for studying interactions between ssDNA phages and marine bacteria.</p

Image_1_A Virus Infecting Marine Photoheterotrophic Alphaproteobacteria (Citromicrobium spp.) Defines a New Lineage of ssDNA Viruses.TIF

<p>In recent metagenomic studies, single-stranded DNA (ssDNA) viruses that infect bacteria have been shown to be diverse and prevalent in the ocean; however, there are few isolates of marine ssDNA phages. Here, we report on a cultivated ssDNA phage (vB_Cib_ssDNA_P1) that infects Citromicrobium bathyomarinum RCC1878 (family Sphingomonadaceae), and other members of the genus. This is the first ssDNA phage reported to infect marine alphaproteobacteria, and represents a newly recognized lineage of the Microviridae infecting members of Sphingomonadaceae, the Amoyvirinae. The ∼26 nm diameter polyhedral capsid contains a 4,360 bp genome with 6 open reading frames (ORFs) and a 59.3% G+C content. ORF1 encodes the capsid protein and ORF3 encodes the replication initiator protein. The replication cycle is ∼5 h, followed by a burst releasing about 180 infectious particles. The closest relative of vB_Cib_ssDNA_P1 is a prophage within the genome of Novosphingobium tardaugens strain NBRC16725. Phylogenetic analysis indicates that the vB_Cib_ssDNA_P1 phage and two related prophages, as well as an environmental sequence, form a novel group within the Microviridae. Our results indicate that this is a previously unknown lineage of ssDNA viruses which also supplies a new model system for studying interactions between ssDNA phages and marine bacteria.</p