Uniaxial Swelling in LC Hydrogels Formed by Two-Step Cross-Linking

Molecularly oriented hydrogels of sacran, which is a supergiant liquid crystalline polysaccharide extracted from <i>Aphanothece sacrum</i> biomaterials, showing ultrahigh anisotropy of swelling is successfully prepared by two-step chemical cross-linking. Divinyl sulfone (DVS) works as a chemical cross-linker of sacran chains in a dilute aqueous solution to form hydrogels, but some of the added DVS remains in the hydrogel without cross-linking. The remaining DVS cross-links further with the preformed networks of sacran chains in liquid crystalline state during slow drying to produce in-plane oriented xerogels. The xerogels show heterogeneous anisotropy in the successive swellings steps; the linear swelling ratio in the thickness direction is 10000–40000-fold higher than that in the width direction due to the molecular orientation of the sacran hydrogels. X-ray diffraction imaging of the hydrogels reveal not only the orientation of the xerogel films but also the unusual orientation of water molecules binding to sacran networks in the hydrogel state

Enhancing Passive Transport of Micro/Nano Particles into Cells by Oxidized Carbon Black

Uses of micro-/nano-sized particles to deliver biologically active entities into cells are common for medical therapeutics and prophylactics and also for cellular experiments. Enhancing cellular uptake and avoiding destruction by lysosomes are desirable for general particulate drug delivery systems. Here, we show that the relatively nontoxic, negatively charged oxidized carbon black particles (OCBs) can enhance cellular penetration of micro- and nano-particles. Experiments with retinal-grafted chitosan particles (PRPs) with hydrodynamic sizes of 1200 ± 51.5, 540 ± 29.0, and 430 ± 11.0 nm (three-sized model particles) indicate that only the sub-micron-sized particles can penetrate the first layer of multilayered liposomes. However, in the presence of OCBs, the micron-sized PRPs and the two submicron-sized PRPs can rapidly enter the interiors of all layers of the multilayered liposomes. Very low cellular uptakes of micro- and submicron-sized PRPs into keratinocytes cells are usually observed. However, in the presence of OCBs, faster and higher cellular uptakes of all of the three-sized PRPs are clearly noticed. Intracellular traffic monitoring of PRP uptake into HepG2 cells in the presence of OCBs revealed that the PRPs did not co-localize with endosomes, suggesting a nonendocytic uptake process. This demonstration of OCB’s ability to enhance cellular uptake of micro- and submicron-particles should open up an easy strategy to effectively send various carriers into cells

Enhancing Passive Transport of Micro/Nano Particles into Cells by Oxidized Carbon Black

Uses of micro-/nano-sized particles to deliver biologically active entities into cells are common for medical therapeutics and prophylactics and also for cellular experiments. Enhancing cellular uptake and avoiding destruction by lysosomes are desirable for general particulate drug delivery systems. Here, we show that the relatively nontoxic, negatively charged oxidized carbon black particles (OCBs) can enhance cellular penetration of micro- and nano-particles. Experiments with retinal-grafted chitosan particles (PRPs) with hydrodynamic sizes of 1200 ± 51.5, 540 ± 29.0, and 430 ± 11.0 nm (three-sized model particles) indicate that only the sub-micron-sized particles can penetrate the first layer of multilayered liposomes. However, in the presence of OCBs, the micron-sized PRPs and the two submicron-sized PRPs can rapidly enter the interiors of all layers of the multilayered liposomes. Very low cellular uptakes of micro- and submicron-sized PRPs into keratinocytes cells are usually observed. However, in the presence of OCBs, faster and higher cellular uptakes of all of the three-sized PRPs are clearly noticed. Intracellular traffic monitoring of PRP uptake into HepG2 cells in the presence of OCBs revealed that the PRPs did not co-localize with endosomes, suggesting a nonendocytic uptake process. This demonstration of OCB’s ability to enhance cellular uptake of micro- and submicron-particles should open up an easy strategy to effectively send various carriers into cells

Bringing Macromolecules into Cells and Evading Endosomes by Oxidized Carbon Nanoparticles

A great challenge exists in finding safe, simple, and effective delivery strategies to bring matters across cell membrane. Popular methods such as viral vectors, positively charged particles and cell penetrating peptides possess some of the following drawbacks: safety issues, lysosome trapping, limited loading capacity, and toxicity, whereas electroporation produces severe damages on both cargoes and cells. Here, we show that a serendipitously discovered, relatively nontoxic, water dispersible, stable, negatively charged, oxidized carbon nanoparticle, prepared from graphite, could deliver macromolecules into cells, without getting trapped in a lysosome. The ability of the particles to induce transient pores on lipid bilayer membranes of cell-sized liposomes was demonstrated. Delivering 12-base-long pyrrolidinyl peptide nucleic acids with d-prolyl-(1<i>S</i>,2<i>S</i>)-2-aminocyclopentanecarboxylic acid backbone (acpcPNA) complementary to the antisense strand of the NF-κB binding site in the promoter region of the <i>Il6</i> gene into the macrophage cell line, RAW 264.7, by our particles resulted in an obvious accumulation of the acpcPNAs in the nucleus and decreased <i>Il6</i> mRNA and IL-6 protein levels upon stimulation. We anticipate this work to be a starting point in a new drug delivery strategy, which involves the nanoparticle that can induce a transient pore on the lipid bilayer membrane