Mucus layers, viscoelastic gels abundant in anionic mucin glycoproteins, obstruct therapeutic delivery across all mucosal surfaces. We found that strongly positively charged nanoparticles (NPs) rapidly adsorb a mucin protein corona in mucus, impeding cell binding and uptake. To overcome this, we developed mucus-evading, cell-adhesive (MECS) NPs with variable surface charge using Flash NanoPrecipitation, by blending a neutral poly(ethylene glycol) (PEG) corona for mucus transport with a small amount, 5 wt%, of polycationic dimethylaminoethyl methacrylate (PDMAEMA) for increased cell targeting.
View Article and Find Full Text PDFMucus is a dynamic biological hydrogel, composed primarily of the glycoprotein mucin, exhibits unique biophysical properties and forms a barrier protecting cells against a broad-spectrum of viruses. Here, this work develops a polyglycerol sulfate-based dendronized mucin-inspired copolymer (MICP-1) with ≈10% repeating units of activated disulfide as cross-linking sites. Cryo-electron microscopy (Cryo-EM) analysis of MICP-1 reveals an elongated single-chain fiber morphology.
View Article and Find Full Text PDFMany bacteria live in polymeric fluids, such as mucus, environmental polysaccharides, and extracellular polymers in biofilms. However, lab studies typically focus on cells in polymer-free fluids. Here, we show that interactions with polymers shape a fundamental feature of bacterial life-how they proliferate in space in multicellular colonies.
View Article and Find Full Text PDFProtein-polymer conjugates combine the stability of polymers with the diversity, specificity, and functionality of proteins. The resulting hybrid materials can display properties not found in the individual components and can be particularly relevant for engineering new functionalities. Ice-binding proteins have many potential biotechnical and biomedical applications.
View Article and Find Full Text PDFMethods Mol Biol
November 2023
Antifreeze proteins (AFPs) are biomolecules that can bind to ice and hinder its growth, thus holding significant potential for biotechnological and biomedical applications. AFPs are a subset of ice-binding proteins (IBPs) and are found in various organisms across different life kingdoms. This mini-review investigates the underlying mechanisms by which AFPs impede ice growth, emphasizing the disparities between hyperactive and moderate AFPs.
View Article and Find Full Text PDFOne of the biggest threats for bacteria-based bioreactors in the biotechnology industry is infections caused by bacterial viruses called bacteriophages. More than 70% of companies admitted to encountering this problem. Despite phage infections being such a dangerous and widespread risk, to date, there are no effective methods to avoid them.
View Article and Find Full Text PDFProtein-polymer conjugates are a class of molecules that combine the stability of polymers with the diversity, specificity, and functionality of biomolecules. These bioconjugates can result in hybrid materials that display properties not found in their individual components and can be particularly relevant for drug delivery applications. Engineering amphiphilicity into these bioconjugate materials can lead to phase separation and the assembly of high-order structures.
View Article and Find Full Text PDFDeveloping molecules that emulate the properties of naturally occurring ice-binding proteins (IBPs) is a daunting challenge. Rather than relying on the (limited) existing structure-property relationships that have been established for IBPs, here we report the use of phage display for the identification of short peptide mimics of IBPs. To this end, an ice-affinity selection protocol is developed, which enables the selection of a cyclic ice-binding peptide containing just 14 amino acids.
View Article and Find Full Text PDFMagnetic actuation provides a low-cost, simple method for droplet manipulation on a digital microfluidic platform. The impetus to move the droplets on a low friction surface can come from internal superparamagnetic particles or paramagnetic salts. Recently, the use of microbes for bio-actuation has been established, where the thrust produced by the microbes can be exploited to exert the force required for droplet movement.
View Article and Find Full Text PDFGram-negative bacteria produce repeats-in-toxin adhesion proteins (RTX adhesins) to facilitate microbial adhesion. These large, multidomain proteins share a common architecture comprised of four regions. First to emerge from the bacterium, C terminal end leading, is the RTX export sequence that directs the protein through the type 1 secretion system (T1SS).
View Article and Find Full Text PDFMagnetotactic bacteria (MTB) migrate in complex porous sediments where fluid flow is ubiquitous. Here, we demonstrate that magnetotaxis enables MTB to migrate effectively through porous micromodels. Directed MTB can circumvent curved obstacles by traveling along the boundaries and pass flat obstacles by repeatedly switching between forward and backward runs.
View Article and Find Full Text PDFMagnetotactic bacteria (MTB) play an important role in Earth's biogeochemical cycles by transporting minerals in aquatic ecosystems, and have shown promise for controlled transport of microscale objects in flow conditions. However, how MTB traverse complex flow environments is not clear. Here, using microfluidics and high-speed imaging, it is revealed that magnetotaxis enables directed motion of Magnetospirillum magneticum over long distances in flow velocities ranging from 2 to 1260 µm s , corresponding to shear rates ranging from 0.
View Article and Find Full Text PDFBacterial adhesins are modular cell-surface proteins that mediate adherence to other cells, surfaces, and ligands. The Antarctic bacterium uses a 1.5-MDa adhesin comprising over 130 domains to position it on ice at the top of the water column for better access to oxygen and nutrients.
View Article and Find Full Text PDFAntifreeze proteins (AFPs) are a class of ice-binding proteins that promote survival of a variety of cold-adapted organisms by decreasing the freezing temperature of bodily fluids. A growing number of biomedical, agricultural, and commercial products, such as organs, foods, and industrial fluids, have benefited from the ability of AFPs to control ice crystal growth and prevent ice recrystallization at subzero temperatures. One limitation of AFP use in these latter contexts is their tendency to denature and irreversibly lose activity at the elevated temperatures of certain industrial processing or large-scale AFP production.
View Article and Find Full Text PDFAntifreeze proteins (AFPs) are small monomeric proteins that adsorb to the surface of ice to inhibit ice crystal growth and impart freeze resistance to the organisms producing them. Previously, monomeric AFPs have been conjugated to the termini of branched polymers to increase their activity through the simultaneous binding of more than one AFP to ice. Here, we describe a superior approach to increasing AFP activity through oligomerization that eliminates the need for conjugation reactions with varying levels of efficiency.
View Article and Find Full Text PDFBy binding to ice, antifreeze proteins (AFPs) depress the freezing point of a solution and inhibit ice recrystallization if freezing does occur. Previous work showed that the activity of an AFP was incrementally increased by fusing it to another protein. Even larger increases in activity were achieved by doubling the number of ice-binding sites by dimerization.
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