An improved approach for the surface modification of poly(dimethylsiloxane) (PDMS) using carboxymethyl cellulose (CMC), carboxymethyl beta-1,3-dextran (CMD), and alginic acid (AA) was investigated. The PDMS substrates were first oxidized in a H(2)SO(4)/H(2)O(2) solution to transform the Si-CH(3) groups on their surfaces into Si-OH groups. Then methacrylate groups were grafted onto the substrates through a silanization reaction using 3-(trimethoxysilyl)propyl methacrylate. Sequentially, cysteamine was conjugated onto the silanized surfaces by the reaction between the thiol and methacrylate groups under 254 nm UV exposure. Afterward, the amino-terminated PDMS substrates were sequentially reacted with CMC, CMD, and AA in the presence of N-hydroxysuccinimide and 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide, resulting in the grafting of polysaccharides onto PDMS surfaces. The composition and chemical state of the modified surfaces were characterized by X-ray photoelectron spectroscopy (XPS). In addition, the stability and dynamic characteristics of the polysaccharide-grafted PDMS substrates were investigated by XPS and temporal contact angle experiments. A protein adsorption assay using bovine serum albumin (BSA), chicken egg albumin, lysozyme, and RNase-A showed that the introduction of CMD and AA can reduce the adsorption of negatively charged BSA and chicken egg albumin, but increase the adsorption of the positively charged lysozyme and RNase-A. However, CMC-modified PDMS surfaces showed protein-repelling properties, regardless of whether the protein was positively or negatively charged. A cell culture and migration study of glioma C6, MKN-45, MCF-7, and HepG-2 cells revealed that the polysaccharide-modified PDMS greatly improved the cytocompatibility of native PDMS.
A new coordination polymer, [Co 2 (L) 2 (4,4'-bipy)] n •3nH 2 O (1) based on 5-(3-methyl-5-phenyl-4H-1,2,4-triazol-4-yl)isophthalic acid (H 2 L) and 4,4'-bipyridine (4,4'-bipy) has been hydrothermally synthesized and characterized by single-crystal X-ray diffraction, XRPD, IR, and elemental analysis. Temperature-dependent magnetic susceptibility and thermal degradation for 1 were also studied. The asymmetric unit of compound 1 consists of two crystallographically independent Co(II) ion, two L 2− ligand, one 4,4'-bipy ligand, and three lattice water molecules. The 2D triangle networks were linked by the bridging 4,4'-bipy ligand to give rise to a 2-fold interpenetrated 3D architecture. The simplest cyclic motif of the 2D networks is a triangle ring consisting of three Co(II) cations and three L 2− ligands. So we can define Co(II) ions as 4-connected nodes and the L 2− ligands as 3-connected nodes. Thus, the 3D structure can be described as a 2-fold parallel interpenetrated ins InS 3,4-conn topology.
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