Green and Low-cost Production of Thermally Stable and Carboxylated Cellulose Nanocrystals and Nanofibrils Using Highly Recyclable Dicarboxylic Acids

Here we demonstrate potentially low cost and green productions of high thermally stable and carboxylated cellulose nanocrystals (CNCs) and nanofibrils ...

U.S. Department of Agriculture

The antitumor effects of Indo-3-carbinol (I3C) have been proven in many human carcinoma cells. However, the roles of 3,3-diindolylmethane (DIM), an important polymer converted from I3C under pH 5.0-7.0, on the growth and proliferation of cervical cancer HeLa and SiHa cells still remain unrevealed. In the present study, we investigated the potential anti-proliferative and pro-apoptotic effects of DIM on HeLa and SiHa cells. Cell proliferation was detected by Cell Counting kit-8 and apoptosis was analyzed by flow cytometry. In addition, morphological changes accompanying cell apoptosis were observed using an inverted microscope after Hoechst 33258 staining. In addition, expression changes of proteins involved in the MAPK and PI3K pathways were determined by western blotting. DIM treatment inhibited the proliferation and induced apoptosis of HeLa and SiHa cells significantly in a time- and dose-dependent manner. Moreover, SiHa cells were more sensitive to DIM treatment than HeLa cells (P<0.05). In addition, the expression of ERK, p38 and p-p38, which are involved in the MAPK pathway, was downregulated by DIM treatment. Another protein involved in the MAPK pathway, JNK, was upregulated. Furthermore, DIM treatment significantly suppressed the expression of Akt, p-Akt, PI3K p110α, PI3K p110β, PI3K class III, GSK3-β, p-PDK1 and p-c-Raf which are involved in the PI3K pathway. These results demonstrate that DIM exerts antitumor effects on HeLa and SiHa cells through its anti-proliferative and pro-apoptotic roles, especially for SiHa cells. The molecular mechanism for these effects may be related to its regulatory effects on MAPK and PI3K pathway and apoptosis proteins. DIM may be a preventive and therapeutic agent against cervical cancer.

Anti-proliferative and pro-apoptotic effects of 3,3'-diindolylmethane in human cervical cancer cells.

Inspired by the rational design concept, a novel antimicrobial agent zeolitic imidazolate framework-8 (ZIF-8)/graphene oxide (GO) was synthesized and utilized as a novel and efficient bactericidal agent to fabricate antimicrobial thin film nanocomposite (TFN) membranes via interfacial polymerization. The resultant hybrid nanosheets not only integrates the merits of both ZIF-8 and GO but also yields a uniform dispersion of ZIF-8 onto GO nanosheets simultaneously, thus effectively eliminating the agglomeration of ZIF-8 in the active layer of membranes. A ZIF-8/GO thin film nanocomposite (TFN-ZG) membrane with typical water permeability (40.63 L m(-2) h(-1) MPa(-1)) allows for efficient bivalent salt removal (rejections of Na2SO4 and MgSO4 were 100% and 77%, respectively). Furthermore, the synthesized ZIF-8/GO nanocomposites were verified to have an optimal antimicrobial activity (MIC,128 μg/mL) in comparison with ZIF-8 and GO separately, which sufficiently endowed the TFN-ZG membrane with excellent antimicrobial activity (84.3% for TFN-ZG3). Besides, the antimicrobial mechanisms of ZIF-8/GO hybrid nanosheets and TFN-ZG membranes were proposed. ZIF-8/GO functionalized membrane with high antimicrobial activity and salt retention denoted its great potential in water desalination, and we suggest that ZIF-8 based crystal may offer a new pathway for the synthesis of a multifunctional bactericide.

Zeolitic Imidazolate Framework/Graphene Oxide Hybrid Nanosheets Functionalized Thin Film Nanocomposite Membrane for Enhanced Antimicrobial Performance.

Organized arrays of halloysite clay nanotubes have great potential in molecular separation, absorption, and biomedical applications. A highly oriented layer of halloysite on polyacrylonitrile porous membrane was prepared via a facile evaporation-induced method. Scanning electronic microscopy, surface attenuated total reflection Fourier transform infrared spectroscopy, and energy dispersive X-ray spectroscopy mapping indicated formation of the nanoarchitecture-controlled membrane. The well-ordered nanotube coating allowed for the excellent dye rejection (97.7% for reactive black 5) with high salt permeation (86.5% for aqueous NaCl), and thus these membranes were suitable for dye purification or concentration. These well-aligned nanotubes' composite membranes also showed very good fouling resistance against dye accumulation and bovine serum albumin adsorption as compared to the pristine polyacrylonitrile or membrane coated with disordered halloysite layer.

Oriented Clay Nanotube Membrane Assembled on Microporous Polymeric Substrates.

Metal-organic frameworks (MOFs) are studied for the design of advanced nanocomposite membranes, primarily due to their ultra-high surface area, regular and highly tunable pore structures, and favorable polymer affinity. However, the development of engineered MOF-based membranes for water treatment lags behind. Here, thin-film nanocomposite (TFN) membranes containing poly(sodium 4-styrenesulfonate) (PSS) modified ZIF-8 (mZIF) in a polyamide (PA) layer were constructed via a facile interfacial polymerization (IP) method. The modified hydrophilic mZIF nanoparticles were evenly dispersed into an aqueous solution comprising piperazine (PIP) monomers, followed by polymerizing with trimesoyl chloride (TMC) to form a composite PA film. FT-IR spectroscopy and XPS analyses confirm the presence of mZIF nanoparticles on the top layer of the membranes. SEM and AFM images evince a retiform morphology of the TFN-mZIF membrane surface, which is intimately linked to the hydrophilicity and adsorption capacity of mZIF nanoparticles. Furthermore, the effect of different ZIF-8 loadings on the overall membrane performance was studied. Introducing the hydrophilizing mZIF nanoparticles not only furnishes the PA layer with a better surface hydrophilicity and more negative charge, but it also more than doubles the original water permeability, while maintaining a high retention of Na2SO4. The ultra-high retentions of reactive dyes (e.g., reactive black 5 and reactive blue 2, > 99.0%) for mZIF functionalized PA membranes ensure their superior nanofiltration performance. This facile, cost-effective strategy will provide a useful guideline to integrate with other modified hydrophilic MOFs to design nanofiltration for water treatment.

Junyong Zhu

Forest Products Laboratory,
U.S. Forest Service,
Forest Products Laboratory, U.S. Forest Service

U.S. Department of Agriculture

Green and Low-cost Production of Thermally Stable and Carboxylated Cellulose Nanocrystals and Nanofibrils Using Highly Recyclable Dicarboxylic Acids

Junyong Zhu

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U.S. Department of Agriculture

Green and Low-cost Production of Thermally Stable and Carboxylated Cellulose Nanocrystals and Nanofibrils Using Highly Recyclable Dicarboxylic Acids

Forest Products Laboratory,
U.S. Forest Service,
Forest Products Laboratory, U.S. Forest Service