The structure-antibacterial activity relationship between the small molecular compounds and polymers are still elusive. Here, imidazolium-type ionic liquid (IL) monomers and their corresponding poly(ionic liquids) (PILs) and poly(ionic liquid) membranes were synthesized. The effect of chemical structure, including carbon chain length of substitution at the N3 position and charge density of cations (mono- or bis-imidazolium) on the antimicrobial activities against both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was investigated by determination of minimum inhibitory concentration (MIC). The antibacterial activities of both ILs and PILs were improved with the increase of the alkyl chain length and higher charge density (bis-cations) of imidazolium cations. Moreover, PILs exhibited lower MIC values relative to the IL monomers. However, the antibacterial activities of PIL membranes showed no correlation to those of their analogous small molecule IL monomers and PILs, which increased with the charge density (bis-cations) while decreasing with the increase of alkyl chain length. The results indicated that antibacterial property studies on small molecules and homopolymers may not provide a solid basis for evaluating that in corresponding polymer membranes.

Pyrrolidinium-type small molecule ionic liquids (ILs), poly(ionic liquid) (PIL) homopolymers, and their corresponding PIL membranes were synthesized and used for antibacterial applications. The influences of substitutions at the N position of pyrrolidinium cation on the antimicrobial activities against both Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) were studied by minimum inhibitory concentration (MIC). The antibacterial efficiency of both the small molecule ILs and PIL homopolymers increased with the increase of the alkyl chain length of substitutions. Furthermore, PIL homopolymers show relatively lower MIC values, indicating better antimicrobial activities than those of the corresponding small molecule ILs. However, the antibacterial properties of the PIL membranes are contrary to corresponding ILs and PIL homopolymers, which reduce with the increase of alkyl chain length. Furthermore, the resultant PIL membranes show excellent hemocompatibility and low cytotoxicity toward human cells, demonstrating clinical feasibility in topical applications.

The development of materials with intrinsically antimicrobial activities has attracted great interest. Herein, we report the synthesis of free-standing and robust poly(ionic liquid) (PIL) membranes with high antibacterial activities by in situ photo-cross-linking of an ionic liquid monomer and followed by anion-exchange with an amino acid (L-proline (Pro) or L-tryptophan (Trp)). The resultant PIL-based membranes with excellent robustness exhibit high antimicrobial properties against both Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) and present no significant hemolysis and cytotoxicity toward human red blood and skin fibroblast cells, as well as low adsorption of bovine serum albumin. The synthesized PIL-Trp membranes exhibit the highest antibacterial efficiency due to the synergistic attributes of both imidazolium cation and Trp − anion. Furthermore, all the PIL-based membranes exhibit long-term antibacterial stability, which demonstrates clinical feasibility in topical applications.

Imidazolium (Im), quaternary ammonium (Qa), and 1,4-diazabicyclo[2.2.2]octane-1,4-diium (DABCO-diium) cation-based small molecule cationic compounds and their corresponding side-chain/main-chain cationic polymers were synthesized.

In this work, we present a systematic study on the precipitation behavior and mechanical properties of a FeCoNiCr-based high-entropy alloy alloyed with dilute amounts of Ti and Al, (FeCoNiCr) 100-x-y Ti x Al y (where x=1~3, y=4~9 at.%). It was found that, upon aging, nano-sized L1 2-Ni 3 (Ti, Al) particles are formed within grains, whilst L2 1-(Ni, Co) 2 TiAl Heusler particles are formed mainly along grain boundaries. The relative thermal stability of the two phases were studied at different aging temperatures (700-900 °C) with various durations of time (up to 48 h) and the results were directly compared with Thermo-calc calculations. Tensile tests were also conducted on alloys aged under different conditions. The measured properties, including strength and ductility, were correlated with the microstructure of aged (FeCoNiCr) 100-x-y Ti x Al y alloys, with particular attention on the distribution and morphology of the two kinds of precipitate. Whereas both phases could contribute to the strengthening of the alloys via either Orowan bowing or particle shearing mechanism, the brittle (Ni, Co) 2 TiAl Heusler phase was found to mainly affect the tensile plasticity. A simple composite model was proposed to describe the plastic strain of alloys. Based on observed microstructure and its corresponding mechanical performance, the alloy with the composition of (FeCoNiCr) 94 Ti 2 Al 4 , when aged between 700 and 800 °C, gives the best balanced strength/ductility properties.

A novel surface-enhanced Raman scattering (SERS) sensor is developed for real-time and highly repeatable detection of trace chemical and biological indicators. The sensor consists of a polydimethylsiloxane (PDMS) microchannel cap and a nanopillar forest-based open SERS-active substrate. The nanopillar forests are fabricated based on a new oxygen-plasma-stripping-of-photoresist technique. The enhancement factor (EF) of the SERS-active substrate reaches 6.06 × 10(6) , and the EF of the SERS sensor is about 4 times lower due to the influence of the PDMS cap. However, the sensor shows much higher measurement repeatability than the open substrate, and it reduces the sample preparation time from several hours to a few minutes, which makes the device more reliable and facile for trace chemical and biological analysis.

Dimethylation of histone H3 lysine 9 (H3K9me2) is an important epigenetic mark associated with transcription repression. Here, we identified PHF8, a JmjC-domain-containing protein, as a histone demethylase specific for this repressing mark. Recombinant full-length wild type protein could remove methylation from H3K9me2, but mutation of a conserved histidine to alanine H247A abolished the demethylase activity. Overexpressed exogenous PHF8 was colocalized with B23 staining. Endogenous PHF8 was also colocalized with B23 and fibrillarin, two well-established nucleolus proteins, suggesting that PHF8 is localized in the nucleolus and may regulate rRNA transcription. Indeed, PHF8 bound to the promoter region of the rDNA gene. Knockdown of PHF8 reduced the expression of rRNA, and overexpression of the gene resulted in upregulation of rRNA transcript. Concomitantly, H3K9me2 level was elevated in the promoter region of the rDNA gene in PHF8 knockdown cells and reduced significantly when the wild type but not the catalytically inactive H247A mutant PHF8 was overexpressed. Thus, our study identified a histone demethylase for H3K9me2 that regulates rRNA transcription.

Herein, a series of quaternary ammonium (Qa) or imidazolium (Im) cation-based poly(ionic liquid) (PIL) membranes and their corresponding zinc ion coordinated PIL membranes were synthesized. The effects of chemical structure, including organic cations, alkyl side chain of substitution, and zinc atoms on the antimicrobial activities against Escherichia coli, Staphylococcus aureus, and Candida albicans were investigated. The Zn-containing PIL membranes show higher antibacterial activities compared to those of pristine PIL membranes due to the synergistic attributes of both organic cations (Qa or Im) and zinc atoms. A wound healing test using methicillin-resistant S. aureus infected mouse as the model further demonstrated that zinc ion coordinated PIL membranes were antibacterially active, biologically safe, and may have potential application as an antimicrobial wound dressing in a clinical setting.