Our research in the media
Article on superadhesive peptides by Heng Chang makes the cover of Materials Chemistry (2021)
ABSTRACT:In this study, using the surface force apparatus, we report engineered peptides with short sequences of phenylalanine (F) and lysine (K) amino acids capable of forming the most efficient cation-π interactions reported for underwater adhesive systems in the literature to date. This outstanding cation-π binding efficiency can be achieved between surfaces coated by these peptides when an isolated K amino acid is flanked by F amino acids in the peptide sequence. Surface force analysis and molecular dynamic simulation reveal that such sequence of amino acids minimizes repulsive hydration forces that prevent effective cation-π interactions. .....more
Article on phyrtoglycogen nanoparticles published by Vahid in ACS Nano makes the news (2021)
ABSTRACT: Phytoglycogen nanoparticles (PhG NPs), a single-molecule highly branched polysaccharide, exhibit excellent water retention, due to the abundance of close-packed
hydroxyl groups forming hydrogen bonds with water. Here we report lubrication properties of close-packed adsorbed monolayers of PhG NPs acting as boundary lubricants. Using direct
surface force measurements, we show that the hydrated nature of the NP layer results in its striking lubrication performance, with two distinct confinement-controlled friction coefficients. In the weak- to moderate-confinement regime, when the NP layer is compressed down to 8% of its original thickness under a normal pressure of up to 2.4 MPa, the NPs lubricate the surface with a friction coefficient of 10−3. In the strong-confinement regime, with 6.5% of the original layer thickness under a normal pressure of up to 8.1 MPa, the friction coefficient was 10−2.......more
Article on microgels superdiffusion in Nat. Comm. by Pierre-Luc makes the news in Nature Reviews in Chemistry (2019)
ABSTRACT:Nanoparticles keep surprising us with behaviours that contradict our intuition based on our understanding of bulk materials. Now, Xavier Banquy, Vincent Martinez and colleagues report in Nature Communications that soft nanoparticles diffuse through a
polymeric medium much faster than solid nanoparticles of the same size. Because of their very small size, nanoparticles have been identified as ideal carriers of small molecules in
many technological applications — from water desalination to medicine — as they can penetrate through intricate, porous membranes. However, if the pores of the membrane are smaller than the nanoparticles themselves, then their diffusion becomes very hard to
predict. As drug delivery systems, large nanoparticles have been found to be better and more stable carriers than small nanoparticles, but these.....more
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Article on antifouling coatings makes cover of Angewandte Chemie (2018)
ABSTRACT:Demand for long‐lasting antifouling surfaces has steered the development of accessible, novel, biocompatible and environmentally friendly materials. Inspired by lubricin (LUB), a component of mammalian synovial fluid with excellent antifouling properties, three block polymers offering stability, efficacy, and ease of use were designed. The bottlebrush‐structured polymers adsorbed strongly on silica surfaces in less than 10 minutes by a simple drop casting or online exposure method and were extremely stable in high‐salinity solutions and across a wide pH range. Antifouling properties against proteins and bacteria were evaluated with different techniques and ultralow fouling properties...more
Research on cartilage substitutes and artificial synovial fluid ranked in the top 10 discoveries of the year by the Arthritis Society(2018)
Jimmy Faivre doctoral research was highlighted by the Arthritis Society as one of the most important advances of the year in the field...more
Article in C&EN on polymer loops published in ACS Nano(2016)
Artificial joint implants get worn out over time, requiring replacement every 10 to 15 years. Polymer coatings could extend the lifetime of the implants by decreasing friction on the joint and minimizing wear. The ideal polymer would also resist protein adsorption and cell adhesion, which can trigger an inflammatory response. Now, researchers describe a polymer that attaches strongly to a variety of surfaces and exhibits enhanced lubricating and antifouling properties.....More
Seeing membrane fusion in action(2015)
Cells are biological wonders. Throughout billions of years of existence on Earth, these tiny units of life have evolved to collaborate at the smallest levels in promoting, preserving and protecting the organism they comprise. Among these functions is the transport of lipids and other biomacromolecules between cells via membrane adhesion and fusion — processes that occur in many biological functions, including waste transport, egg fertilization and digestion. At UC Santa Barbara, chemical engineers have developed a way to directly observe both the forces present and the behavior that occurs during cell hemifusion, a process by which only the outer layers of the lipid bilayer of cell membranes merge. While many different techniques have been used to observe membrane hemifusion, simultaneous measurements of membrane thickness and interaction forces present a greater challenge, according to Dong Woog Lee, lead author of a paper that appears in the journal Nature Communications.....More
Article on Artificial lubricin makes news in C&EN (2014)
ABSTRACT: When doctors implant artificial joints in patients, they usually have toreplace the devices after 10 years because the lack of good lubricationcauses the joints to wear out. To find a better water-based lubricant,researchers now have synthesized a polymer that mimics thestructure and function of lubricin, a protein that occurs naturallyin the fluid that cushions our joints (J. Am. Chem. Soc. 2014, DOI:10.1021/ja501770y)
The key to lubricin’s lubricating power lies in its structure, says XavierBanquy, a biomaterials chemist at the University of Montreal. Theprotein has two end domains that anchor it to surfaces, and a dense,but springy, area in the middle shaped like a bottle brush. When twolubricin-coated surfaces move toward each other, they don’t actuallytouch; instead the bottle-brush domains touch and compress as theapplied pressure increases. The bottle-brush structure also allowswater, an excellent lubricant, to flow through the material when the twosurfaces are moving past each other. .....More
UCSB press release on our recent research on Multiple Sclerosis (2014)
Using the surface forces apparatus and an atomic force microscope, researchers at UC Santa Barbara have taken a molecular approach to myelin membrane interactions, leading to insights into demyelinating diseases, such as multiple sclerosis. Their research is published in the Proceedings of the National Academy of the Sciences.For a healthy nervous system, axons — the long projections of our nerve cells that run throughout our bodies — must be properly insulated. Much like conventional power cords need electrical insulators around the conducting wires for efficient and effective transfer of current, axons rely on multiple bilayers of myelin to maintain a rapid and optimal transfer of impulses between, for instance, brain and organ, or spinal cord and muscle. These bilayers are composed of lipids (fat molecules), protein and water...More
Review on electrochemical reactions and interfacial forces makes cover of JPC-B (2013)
ABSTRACT: We review recent developments in experimentaltechniques that simultaneously combine measurements ofthe interaction forces or energies between two extendedsurfaces immersed in electrolyte solutionsprimarily aqueouswith simultaneous monitoring of their (electro)chemicalreactions and controlling the electrochemical surface potentialof at least one of the surfaces. Combination of thesecomplementary techniques allows for simultaneous real timemonitoring of angstrom level changes in surface thickness androughness, surface−surface interaction energies, and chargeand mass transferred via electrochemical reactions, dissolution,and adsorption, and/or charging of electric double layers.These techniques employ the surface forces apparatus (SFA)combined with various “electrochemical attachments”...More
UCSB press release on our research on ionic liquids (2013)
A new study by researchers at UC Santa Barbara provides clues into the understanding of the behavior of the charged molecules or particles in ionic liquids. The new framework may lead to the creation of cleaner, more sustainable, and nontoxic batteries, and other sources of chemical power. The research was published in an early online edition of the Proceedings of the National Academy of Sciences."I think this framework would provide a nice strategy to begin discussions toward batteries utilizing ionic liquids," said graduate student researcher Matthew Gebbie, first author of the paper, "Ionic liquids behave as dilute electrolyte solutions." An electrolyte is a compound that is dissolved in a solution –– usually water – ...More
UCSB press release on our research on osteoarthritis (2013)
A new, noninvasive, and low-cost method for the early detection and monitoring of osteoarthritis (arthritis caused by wear and tear) may be on its way, thanks to research by UC Santa Barbara scientists from the Department of Chemical Engineering and the Department of Materials.
By studying patterns of friction between cartilage pads, the researchers discovered a different type of friction that is more likely to cause wear and damage. Their work suggests ways to detect this friction, and points to new research directions for getting to the root cause of arthritis. The findings are published in the recent issue of the Proceedings of the National Academy of Science.Imagine going to the doctor for your aching knees. For some, this may involve uncomfortable needle sticks to draw blood for lab tests, ...More