A novel method for flexibly implementing sample dialysis on microchips is introduced. Nanoporous polymer membranes (5-20 pm thickness) with up to 1OOO:l aspect ratio are fabricated in-situ on silica microchips via photopatterned phase-separation polymerization. These membranes enable selective diffusion of molecules smaller than a cutoff specified by the membrane pore size. Diffusion measuremen...

Since its introduction by Robert Koch in 1882, agar has been the most commonly used substrate for the growth and study of bacteria. Agar consists of alternating blocks of D-galactose and 3,6-anhydro-L-galactose and is a polysaccharide with a variety of characteristics that are useful for culturing bacteria: (1) it is biocompatible; (2) it is inert to metabolism and degradation by bacteria; (3) ...

Complex carbohydrates on the surfaces of eukaryotic cells are thought to participate in a wide variety of cell-cell interactions. A model system has therefore been developed to study these processes. In the present experiments, the ability of chicken hepatocytes to recognize and adhere to sugars covalently linked to polyacrylamide gels was investigated. The gels were snythesized by two methods....

The study of hydrogels and their response to external environment is of special interest because of their potential as drug delivery systems,1,2 actuators,3 and separation devices.4,5 Temperature-sensitive hydrogels undergo a reversible swellingdeswelling transition with a small change of temperature near the phase transition point.6 A frequently studied thermosensitive hydrogel is based on sol...

A ribosomal salt (0.5 M KCI) wash factor (RF) that reverses inhibition of protein synthesis in heme-deficient reticulocyte lysates has been resolved from the bulk of MettRNAfmet-binding factor (EIF-1), Co-EIF-I, and EIF-2 (ternary complex dissociation factor, TDF). The purified RF restores protein synthesis activity of heme-deficient lysates to the level observed in the presence of hemin. No di...

During heme deficiency in reticulocyte lysates, a translational inhibitor (heme-regulated inhibitor, HRI) that blocks polypeptide chain initiation is activated. HRI is a protein kinase that specifically phosphorylates the 38,000-dalton subunit of the Met-tRNAfMet binding factor, eIF-2. Phosphorylation of eIF-2 by HRI prevents its interaction with at least two additional factors, resulting in a ...

Multiplexed diffraction gratings were recorded in 300 μm thick layers of biophotopol photopolymer by using two peristrophic multiplexing schemes separately and in combination. In addition, it was shown that riboflavin may be used as polymer initiator in acrylamide photopolymer films and the holographic properties of these films such as diffraction efficiency and dynamic range were compared with...

Protein synthesis by intact Bartlett pear fruits was studied with ripening as measured by flesh softening, chlorophyll degradation, respiration, ethylene synthesis, and malic enzyme activity. Protein synthesis is required for normal ripening, and the proteins synthesized early in the ripening process are, in fact, enzymes required for ripening. l"C-Phenylalanine is differentially incorporated i...

Diffraction from a photonic crystal material composed of a hydrolyzed polymerized crystalline colloidal array (PCCA) can be used to sense pH and ionic strength. The PCCA is a polyacrylamide hydrogel which embeds a polystyrene crystalline colloidal array (CCA). The diffracted wavelength of the PCCA changes as the PCCA volume changes due to the alterations in the CCA lattice constant. We examine ...

We have used the emerging rules for the sequence dependence of DNA bendability to design and test a series of DNA molecules that incorporate strongly into nucleosomes. Competitive reconstitution experiments showed the superiority in histone octamer binding of DNA molecules in which segments consisting exclusively ofA and T or G and C, separated by 2 base pairs (bp), are repeated with a 10-bp pe...