Anti-HIV-1 activity of anionic polymers: a comparative study of candidate microbicides

BACKGROUND: Cellulose acetate phthalate (CAP) in soluble form blocks coreceptor binding sites on the virus envelope glycoprotein gp120 and elicits gp41 six-helix bundle formation, processes involved in virus inactivation. CAP is not soluble at pH < 5.5, normal for microbicide target sites. Therefore, the interaction between insoluble micronized CAP and HIV-1 was studied. Carbomer 974P/BufferGel; carrageenan; cellulose sulfate; dextran/dextrin sulfate, poly(napthalene sulfonate) and poly(styrene-4-sulfonate) are also being considered as anti-HIV-1 microbicides, and their antiviral properties were compared with those of CAP. METHODS: Enzyme linked immunosorbent assays (ELISA) were used to (1) study HIV-1 IIIB and BaL binding to micronized CAP; (2) detect virus disintegration; and (3) measure gp41 six-helix bundle formation. Cells containing integrated HIV-1 LTR linked to the β-gal gene and expressing CD4 and coreceptors CXCR4 or CCR5 were used to measure virus infectivity. RESULTS: 1) HIV-1 IIIB and BaL, respectively, effectively bound to micronized CAP. 2) The interaction between HIV-1 and micronized CAP led to: (a) gp41 six-helix bundle formation; (b) virus disintegration and shedding of envelope glycoproteins; and (c) rapid loss of infectivity. Polymers other than CAP, except Carbomer 974P, elicited gp41 six-helix bundle formation in HIV-1 IIIB but only poly(napthalene sulfonate), in addition to CAP, had this effect on HIV-1 BaL. These polymers differed with respect to their virucidal activities, the differences being more pronounced for HIV-1 BaL. CONCLUSIONS: Micronized CAP is the only candidate topical microbicide with the capacity to remove rapidly by adsorption from physiological fluids HIV-1 of both the X4 and R5 biotypes and is likely to prevent virus contact with target cells. The interaction between micronized CAP and HIV-1 leads to rapid virus inactivation. Among other anionic polymers, cellulose sulfate, BufferGel and aryl sulfonates appear most effective in this respect

Preparation of low density hollow carbon fibers by bi-component gel-spinning method

Sheath&#8211;core polyacrylonitrile (PAN)/poly(methyl methacrylate) fibers were spun through bi-component dry-jet gel-spinning method and were used for fabricating hollow carbon fibers. After optimizing stabilization and carbonization conditions, the resulting PAN-based hollow carbon fibers possessed an average strength and modulus of 3.16 and 275 GPa, respectively. Additionally, 1 wt% carbon nanotubes (CNTs) were added to PAN portion to form PAN+CNT sheath. The PAN+CNT-based hollow carbon fiber had an average strength of 3.24 GPa and modulus of 254 GPa. These hollow carbon fibers can be used for fabricating low density and high performance structural composite materials. &#169; 2015, Springer Science+Business Media New York.close0

Mechanical and thermal properties of organosolv lignin/sodium dodecyl sulphate binary agent-treated polypropylene/chitosan composites

The effects of filler content and chemical treatment on mechanical and thermal properties of polypropylene–chitosan composites were investigated. Filler chemical treatment was carried out by reacting chitosan with organosolv lignin/sodium dodecyl sulphate binary modifying agents under mild condition. Filler–matrix interfacial adhesion enhanced considerably in presence of the binary agent that effectively modified the chitosan surface, leading to increased tensile and impact strength of the composites. Even though the chemical treatments did not change the thermal degradation mechanism of the composites, the obtained results exhibited that the treated composites had better thermal properties than the untreated composites. These finding implies that organosolv lignin-containing binary modifying agents could be a potential reagent to replace synthetic modifying agents