Extreme dilutions, especially homeopathic remedies of 30c, 200c, and higher potencies, are prepared by a process of serial dilution of 1:100 per step. As a result, dilution factors of 10(60), 10(400), or even greater are achieved. Therefore, both the presence of any active ingredient and the therapeutic efficacy of these medicines have been contentious because the existence of even traces of the starting raw materials in them is inconceivable. However, physicochemical studies of these solutions have unequivocally established the presence of the starting raw materials in nanoparticulate form even in these extreme (super-Avogadro, >10(23)) dilutions. In this article, we propose and validate a hypothesis to explain how nanoparticles are retained even at such enormous dilution levels. We show that once the bulk concentration is below a threshold level of a few nanograms/milliliter (ng/mL), at the end of each dilution step, all of the nanoparticles levitate to the surface and are accommodated as a monolayer at the top. This dominant population at the air-liquid interface is preserved and carried to the subsequent step, thereby forming an asymptotic concentration. Thus, all dilutions are only apparent and not real in terms of the concentrations of the starting raw materials.

Hollow fiber membranes are widely used as assist devices for bioartificial liver application. Asymmetric porous polysulfone and polysulfone-tocopheryl polyethylene glycol succinate (Psf-TPGS) composite hollow fiber and flat membranes were prepared by phase inversion procedure and subsequently surface modified with chitosan using sulfonation with concentrated sulfuric acid. Sulfonation induces negative charge on the prepared membrane surface and facilitates the attachment of chitosan amine groups by electrostatic interaction. The surface modification of membrane is stable at room temperature as dictated by presence of nitrogen in XPS analysis and amide linkages in FT-IR spectra. Further, biological studies of the membranes were performed using HepG2 cell line. Chitosan is biocompatible and shows structural similarity to glycosaminoglycans, a native liver ECM component. The chitosan-modified composite Psf and Psf-TPGS membranes have shown enhanced attachment and proliferation of HepG2 cells on outer surface as confirmed by the cell counting, DNA content, confocal microscopy, and SEM micrographs. The cells form a 3D multicellular spheroid structure on the chitosan-modified membranes in significantly larger number as seen in the SEM micrographs. Also, the hemocompatibility of the modified composite membranes were comparable to the unmodified membranes. Thus, the chitosan-modified composite membranes we have developed are bifunctional and have the potential to be used in bioartifical liver application.

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Unsymmetrical 22-oxacorrole containing two aryl groups and one pyrrole group at the meso position was synthesized by condensing one equivalent of 16-oxatripyrrane with one equivalent of meso aryl dipyromethane under mild acid-catalyzed conditions followed by oxidation with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). This [3+2] condensation approach was expected to yield meso-free 25-oxasmaragdyrin but unexpectedly afforded unsymmetrical meso-pyrrole-substituted 22-oxacorrole. We demonstrated the versatility of the reaction by synthesizing four new meso-pyrrole-substituted 22-oxacorroles. The reactivity of α-position of meso-pyrrole was tested by carrying out various functionalization reactions such as bromination, formylation, and nitration and obtained the functionalized meso-pyrrole-substituted 22-oxacorroles in decent yields. The X-ray structure obtained for one of the functionalized meso-pyrrole substituted 22-oxacorrole revealed that the macrocycle was nearly planar and the meso-pyrrole was in the perpendicular orientation with respect to the macrocyclic plane. The meso-pyrrole-substituted 22-oxacorroles absorb strongly in 400-700 nm region with one strong Soret band and four weak Q bands. The 22-oxacorroles are strongly fluorescent and showed emission maxima at ≈650 nm with decent quantum yields and singlet-state lifetimes. The 22-oxacorroles are redox-active and exhibited three irreversible oxidations and one or two reversible reduction(s). A preliminary biological study indicated that meso-pyrrole corroles are biocompatible.