PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 12532011

A reversibly switching surface.

Joerg Lahann·Samir Mitragotri·Thanh-Nga Tran·Hiroki Kaido·Jagannathan Sundaram·Insung S Choi·Saskia Hoffer·Gabor A Somorjai·Robert Langer
View original source ↗Export metadata ↓

Abstract

We report the design of surfaces that exhibit dynamic changes in interfacial properties, such as wettability, in response to an electrical potential. The change in wetting behavior was caused by surface-confined, single-layered molecules undergoing conformational transitions between a hydrophilic and a moderately hydrophobic state. Reversible conformational transitions were confirmed at a molecular level with the use of sum-frequency generation spectroscopy and at a macroscopic level with the use of contact angle measurements. This type of surface design enables amplification of molecular-level conformational transitions to macroscopic changes in surface properties without altering the chemical identity of the surface. Such reversibly switching surfaces may open previously unknown opportunities in interfacial engineering.

Explore related subjects

AdsorptionChemical PhenomenaChemistry, PhysicalElectricityElectrochemistryEstersGoldHydrogen-Ion ConcentrationHydrophobic and Hydrophilic InteractionsMolecular ConformationMolecular StructurePalmitic AcidsSpectrum AnalysisSurface PropertiesThermodynamicsWettabilityJournal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.Research Support, U.S. Gov't, P.H.S.

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Joerg Lahann, Samir Mitragotri, Thanh-Nga Tran, Hiroki Kaido, Jagannathan Sundaram, Insung S Choi, Saskia Hoffer, Gabor A Somorjai, Robert Langer. 2003-01-17. A reversibly switching surface.. https://doi.org/10.1126/science.1078933

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2026

Three-dimensional porous nano-hydroxyapatite@gelatin composite as efficient adsorbent for uranyl ion removal from low-level radioactive wastewater.

The contamination of water resources by uranyl (UO22+) ions poses significant environmental and health risks, requiring the development of efficient and sustainable remediation strategies. Adsorption-based techniques have emerged as promising approaches in the field of UO22+ removal, but the design of cost-effective, high-capacity, and environmentally friendly adsorbents remains challenging. In this study, a three-dimensional porous nano-hydroxyapatite@gelatin (nHAP@Ge) composite was synthesized through glutaraldehyde cross-linking, combining the structural stability of Ge with the high uranium affinity of nHAP. The optimized nHAP@Ge, with a nHAP:Ge mass ratio of 1:0.5, exhibited exceptional UO22+ removal efficiency (97 %), along with high adsorption capacity (364.03 mg/g). Systematic characterizations using scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR) spectroscopy, and X-ray photoelectron spectroscopy (XPS) methods revealed that the porous structure and surface functional groups (-OH, Ca2+, and PO43-) of the material synergistically contributed to binding UO22+ species. Furthermore, the incorporation of nHAP into the Ge framework resulted in enhanced thermal stability while significantly improving the UO22+ adsorption performance. This work presents a scalable, eco-friendly, and recyclable strategy for the effective treatment of uranium-contaminated water, with potential applications in nuclear wastewater treatment and environmental remediation.

Adsorption↗
PubMed2003

Characterization of the lipid-binding domain of the Plasmodium falciparum CTP:phosphocholine cytidylyltransferase through synthetic-peptide studies.

Phospholipid biosynthesis plays a key role in malarial infection and is regulated by CCT (CTP:phosphocholine cytidylyltransferase). This enzyme belongs to the group of amphitropic proteins which are regulated by reversible membrane interaction. To assess the role of the putative membrane-binding domain of Plasmodium falciparum CCT (PfCCT), we synthesized three peptides, K21, V20 and K54 corresponding to residues 274-294, 308-327 and 274-327 of PfCCT respectively. Conformational behaviour of the peptides, their ability to bind to liposomes and to destabilize lipid bilayers, and their insertion properties were investigated by different biophysical techniques. The intercalation mechanisms of the peptides were refined further by using surface-pressure measurements on various monolayers at the air/water interface. In the present study, we show that the three studied peptides are able to bind to anionic and neutral phospholipids, and that they present an alpha-helical conformation upon lipid binding. Peptides V20 and the full-length K54 intercalate their hydrophobic parts into an anionic bilayer and, to a lesser extent, a neutral one for V20. Peptide K21 interacts only superficially with both types of phospholipid vesicles. Adsorption experiments performed at the air/water interface revealed that peptide K54 is strongly surface-active in the absence of lipid. Peptide V20 presents an atypical behaviour in the presence of phosphatidylserine. Whatever the initial surface pressure of a phosphatidylserine film, peptide V20 and phosphatidylserine entities seem linked together in a special organization involving electrostatic and hydrophobic interactions. We showed that PfCCT presents different lipid-dependence properties from other studied CCTs. Although the lipid-binding domain seems to be located in the C-terminal region of the enzyme, as with the mammalian counterpart, the membrane anchorage, which plays a key role in the enzyme regulation, is driven by two alpha-helices, which behave differently from one another.

Adsorption↗
PubMed2003

A new approach for immobilization of oligonucleotides onto piezoelectric quartz crystal for preparation of a nucleic acid sensor for following hybridization.

The aim of this study is to develop a nucleic acid sensor based on piezoelectric crystal microbalance system (QCM) for following hybridization. Piezoelectric quartz crystal surfaces were first treated in a glow-discharge apparatus with ethylene diamine (EDA) plasma at 15 W (discharge power), 2.5 min (incubation time) and 35 ml/min (monomer flow rate) to create amino groups on the crystal surfaces. The thickness of the EDA-plasma film formed was about 43+/-24 A. Then, the amino groups on the crystal surfaces were converted to aldehyde groups by reacting the amino groups with glutaraldehyde (GA) at different conditions. A GA concentration of 2.5% and an incubation time of 2 h were selected as optimal values at this step, corresponding to a GA surface concentration of about 270 ng/cm2. A double strand Oligonucleotides, having one extra base on 5'-end of one of the complementary strands, were immobilized through the amino groups of this base onto the GA-modified crystals. Optimal immobilization conditions were as follows: oligonucleotide concentration: 1 microg/ml; time: 3 h; pH: 9.2 carbonate buffer; ionic strength: 0.1; and temperature: 20 degrees C. The QCM sensor carrying the covalently bound strand was used in the hybridization experiments, which showed that equilibrium is achieved in about 5 min, and the frequency shift measured is related to the concentration of the target strand to be measured within the medium.

Adsorption↗