Search results for "Biomolecule"
showing 10 items of 666 documents
Small-Angle Scattering Techniques for Analyzing Conformational Transitions in Hemocyanins
2004
Publisher Summary The precise delivery of oxygen from respiratory surfaces to the tissues is mediated by cooperative and allosterically regulated carrier proteins, such as hemoglobin or hemocyanin. To establish cooperativity, these proteins must be able to adopt different conformations. These conformations are characterized by different ligand affinities, which have their basis in different structures as is the case for the deoxy and oxy states of human hemoglobin. To understand the cooperative interaction of these molecules at the molecular level, the structures of these conformations must be resolved and the transitions between them must be monitored. Because of the nature of sample prepa…
Carbohydrate nanocarriers in biomedical applications: functionalization and construction
2015
The specific targeting of either tumor cells or immune cells in vivo by carefully designed and appropriately surface-functionalized nanocarriers may become an effective therapeutic treatment for a variety of diseases. Carbohydrates, which are prominent biomolecules, have shown their outstanding ability in balancing the biocompatibility, stability, biodegradability, and functionality of nanocarriers. The recent applications of sugar (mono/oligosaccharides and/or polysaccharides) for the development of nanomedicines are summarized in this review, including the application of carbohydrates for the surface-functionalization of various nanocarriers and for the construction of the nanocarrier its…
Mesoporous silica-based materials for use in electrochemical enzyme nanobiosensors
2012
Abstract Biology and medicine have seen great advancements in the development of enzyme nanobiosensors capable of characterizing and quantifying biomolecules. We provide an overview of mesoporous silica (MPS)-based enzyme nanobiosensors developed for biological and medical applications, and we describe significant advances in these technologies. We review progress in constructing high-performance electrochemical enzyme biosensors. We also discuss: • MCM-41 and SBA-15-modified and MPS composite electrodes for enzyme biosensing; • incorporation of biorecognition elements into MPS material electrodes for enzyme biosensing; and, • MCM-41 and SBA-15-supported electrocatalytic MPS-based electroch…
Studying the role of protein dynamics in an SN2 enzyme reaction using free-energy surfaces and solvent coordinates
2013
Conformational changes are known to be able to drive an enzyme through its catalytic cycle, allowing, for example, substrate binding or product release. However, the influence of protein motions on the chemical step is a controversial issue. One proposal is that the simple equilibrium fluctuations incorporated into transition-state theory are insufficient to account for the catalytic effect of enzymes and that protein motions should be treated dynamically. Here, we propose the use of free-energy surfaces, obtained as a function of both a chemical coordinate and an environmental coordinate, as an efficient way to elucidate the role of protein structure and motions during the reaction. We sho…
A Step into the Future: Applications of Nanoparticle Enzyme Mimics.
2018
We describe elementary concepts, up-to-date developments, and perspectives of the emerging field of nanoparticle enzyme mimics (so-called "nanozymes") at the interface of chemistry, biology, materials, and nanotechnology. The design and synthesis of functional enzyme mimics is a long-standing goal of biomimetic chemistry. Metal complexes, polymers and engineered biomolecules capturing the structure of natural enzymes or their active centers have been made to achieve high rates and enhanced selectivities. Still, the design of new "artificial enzymes" that are not related to proteins but with capacity of production and stability at industrial level, remains a goal. Inorganic nanoparticles bea…
A Polar18F-Labeled Amino Acid Derivative for Click Labeling of Biomolecules
2014
This work describes the synthesis and 18F-labeling of an amino acid based prosthetic group that is able to participate in copper(I)-catalyzed cycloadditions. The prosthetic group can be used for 18F labeling of biomolecules under mild conditions. The synthesis started with L-serine methyl ester, which was derivatized by introducing an alkyne moiety and a leaving group for 18F labeling. Subsequently, 18F labeling as well as deprotection conditions were screened, which resulted in an overall radiochemical yield (RCY) of around 28 %. Furthermore, the 18F-labeled prosthetic group was treated with an azido cyclic Arg-Gly-Asp (cRGD) peptide as a model system in very high RCY of 98 %.
Functional Nanohybrids Based on Dyes and Upconversion Nanoparticles
2020
Upconversion nanoparticles (UCNPs) and dyes are combined to make nanohybrid systems, which take advantage of the synergic relationship between lanthanide (Ln)-based UCNPs and dyes. Ln-UCNPs are inorganic nanophosphors which absorb NIR light and emit narrow emission bands in the UV-NIR region with long luminescence lifetimes. These unique properties, when coordinated properly with dyes of the appropriate photophysical features, produce nanosystems with new photophysical properties. In this context, the UCNP-dye nanohybrids are very promising for potential sensing (ions and biomolecules) and theragnosis (imaging and therapy, e.g. photodynamic therapy).
Quartz Crystal Microbalance for Bioanalytical Applications
2001
The quartz crystal microbalance (QCM) was first introduced as a mass sensor in gas phase and in vacuum. Since oscillator circuits capable of exciting shear vibrations of quartz resonators under liquid load have been developed, the QCM became accepted as a new powerful technique to monitor adsorption processes at solid/liquid interfaces in chemical and biological research rendering the method an attractive low-cost alternative for bioanalytic applications. In the last decade, adsorption of biomolecules on functionalized surfaces turned out to be one of the paramount applications of piezoelectric transducers comprising the interaction of DNA and RNA with complementary strands, specific recogn…
Silica-coated Au@ZnO Janus particles and their stability in epithelial cells
2020
Multicomponent particles have emerged in recent years as new compartmentalized colloids with two sides of different chemistry or polarity that have opened up a wide field of unique applications in medicine, biochemistry, optics, physics and chemistry. A drawback of particles containing a ZnO hemisphere is their low stability in biological environment due to the amphoteric properties of Zn2+. Therefore we have synthesized monodisperse Au@ZnO Janus particles by seed-mediated nucleation and growth whose ZnO domain was coated selectively with a thin SiO2 layer as a protection from the surrounding environment that imparts stability in aqueous media while the Au domain remained untouched. The thi…
Iron and iron-oxide magnetic nanoparticles as signal-amplification elements in electrochemical biosensing
2015
Abstract Growing demands for ultrasensitive biosensing have led to the development of numerous signal-amplification strategies. Based on their unique properties (i.e., electro-conductivity, bio-compatibility and ease of synthesis), various iron magnetic nanoparticles (MNPs) have proved to be an excellent nanomaterial for applications in electrochemical biosensing. This review shows how iron MNPs have made significant contributions in the development of electrochemical nanobiosensors, including immuno-, enzyme, DNA and aptamer types. More importantly, we discuss in detail different aspects of the electrochemical biosensors (e.g., modes of magnetic particles, detection techniques, analytes an…