We show that the exponential length distribution that is typical of actin filaments under physiological conditions dramatically narrows in the presence of (i) crosslinker proteins (ii) polyvalent counterions or (iii) depletion mediated attractions. A simple theoretical model shows that in equilibrium, short-range attractions enhance the tendency of filaments to align parallel to each other, eve...

We have used photo-crosslinking to investigate the structure and dynamics of four-way junction hairpin ribozyme constructs. Four phenylazide photo-crosslinkers were coupled to 2'-NH2-modified U+2 in the substrate and irradiated at different Mg2+ concentrations and temperatures. Consistent with the role of divalent metal ions in hairpin ribozyme folding, we observed more interdomain crosslinks i...

Endogenously and externally generated mechanical forces influence diverse cellular activities, a phenomenon defined as mechanotransduction. Deformation of protein domains by application of stress, previously documented to alter macromolecular interactions in vitro, could mediate these effects. We engineered a photon-emitting system responsive to unfolding of two repeat domains of the actin fila...

In this study, stability of hyaluronic acid (HA) based nanoemulsion was systematically investigated. Factors including zeta potential, pH, crosslinking agents and degree of substitution (DS) were considered to assess their roles in stability. Nanoemulsions prepared from HA-GMS with higher DS showed smaller droplet sizes. In the presence of Ca2+ as a crosslinker, size distribution was improved t...

Abstract Herein, polyvinyl alcohol-carboxymethyl cellulose (PVA-CMC) composite hydrogel membranes were prepared using solution-casting method, where citric acid (CA) was added as crosslinker in different ratios of (7, 10 and12 wt%). Attapulgite clay extracted from Northwestern Desert Borg El-Arab, Egypt; incorporated nanofiller (1, 2, 4, and 5 wt%) into for improving their mechanical/ thermal s...

Cells precisely regulate their frequency-dependent viscoelastic properties in response to chemical and mechanical cues. We use optical trap-based active microrheology using intracellular probes measure the cytoplasmic of fibroblast macrophage cells over a broad frequency range ($\ensuremath{\sim}0.02--350$ Hz). Both cell types show similar behavior, suggesting that mechanisms control cell's are...

In addition to its high affinity for antibody Fc domains, staphylococcal Protein A has been shown to bind certain Fab domains. We investigated this in order to develop a small, recombinant Protein A-binding alternative to immunoglobulin G (IgG) from nanobodies, single-domain antibodies derived from a camelid variant IgG's variable region. We engineered a nanobody with affinity solely for Protei...

In this study, we developed an injectable gelatin-transglutaminase (TGase) gel for cell delivery. The procedure provides a minimally invasive approach to deliver cells into tissue in a manner that improves localization. The results indicate gelatin-TGase to be noncytotoxic and to have adhesive properties that help localize and prevent the scattering of the cells after delivery. The in situ cros...