Fast Optical Chemical and Structural Classification of RNA

As more biological activities of ribonucleic acids continue to emerge, the development of efficient analytical tools for RNA identification and characterization is necessary to acquire an in-depth understanding of their functions and chemical properties. Herein, we demonstrate the capacity of label-free direct surface-enhanced Raman scattering (SERS) analysis to access highly specific structural information on RNAs at the ultrasensitive level. This includes the recognition of distinctive vibrational features of RNAs organized into a variety of conformations (micro-, fully complementary duplex-, small interfering- and short hairpin-RNAs) or characterized by subtle chemical differences (single-base variances, nucleobase modifications and backbone composition). This method represents a key advance in the ribonucleic acid analysis and will have a direct impact in a wide range of different fields, including medical diagnosis, drug design, and biotechnology, by enabling the rapid, high-throughput, simple, and low-cost identification and classification of structurally similar RNAs

The Use of Ni/Sb-SnO2-based Membrane Electrode Assembly for Electrochemical Generation of Ozone and the Decolourisation of Reactive Blue 50 Dye Solutions

Surface enhanced Raman scattering (SERS) “hot spots” are the regions where the electromagnetic field is significantly enhanced, resulting in much greater SERS activity than other areas. Therefore, the engineering and characterization of “hot spots” have attracted much attention. Herein, we have synthesized nanoworms formed by connecting hollow gold nanospheres and investigated their composition as well as their SERS properties, including their potential for simultaneous analysis of multiple species. The three-dimensional nanostructures that led to different SERS activities were investigated using correlated optical/SERS and SEM imaging. Gold nanoworms with hollow nanosphere segments and partial tube formation were confirmed. All highly SERS-active structures were found to be three-dimensional arrays consisting of inter-/intrananoworm interactions; no individual nanospheres were found to give significant SERS signal under the experimental conditions. The major SERS contribution was found to be the electromagnetic coupling effect within the three-dimensional arrays and the localized surface plasmon resonance of the nanostructure was found to have a minimal effect. This study gives insight into the basis of enhancement for these nanoworm structures and adds to the growing body of evidence in relation to nanostructures and surface enhancement of Raman scattering

Fate of Liposomes in the Presence of Phospholipase C and D: From Atomic to Supramolecular Lipid Arrangement

Understanding the origins of lipid membrane bilayer rearrangement in response to external stimuli is an essential component of cell biology and the bottom-up design of liposomes for biomedical applications. The enzymes phospholipase C and D (PLC and PLD) both cleave the phosphorus–oxygen bonds of phosphate esters in phosphatidylcholine (PC) lipids. The atomic position of this hydrolysis reaction has huge implications for the stability of PC-containing self-assembled structures, such as the cell wall and lipid-based vesicle drug delivery vectors. While PLC converts PC to diacylglycerol (DAG), the interaction of PC with PLD produces phosphatidic acid (PA). Here we present a combination of small-angle scattering data and all-atom molecular dynamics simulations, providing insights into the effects of atomic-scale reorganization on the supramolecular assembly of PC membrane bilayers upon enzyme-mediated incorporation of DAG or PA. We observed that PC liposomes completely disintegrate in the presence of PLC, as conversion of PC to DAG progresses. At lower concentrations, DAG molecules within fluid PC bilayers form hydrogen bonds with backbone carbonyl oxygens in neighboring PC molecules and burrow into the hydrophobic region. This leads initially to membrane thinning followed by a swelling of the lamellar phase with increased DAG. At higher DAG concentrations, localized membrane tension causes a change in lipid phase from lamellar to the hexagonal and micellar cubic phases. Molecular dynamics simulations show that this destabilization is also caused in part by the decreased ability of DAG-containing PC membranes to coordinate sodium ions. Conversely, PLD-treated PC liposomes remain stable up to extremely high conversions to PA. Here, the negatively charged PA headgroup attracts significant amounts of sodium ions from the bulk solution to the membrane surface, leading to a swelling of the coordinated water layer. These findings are a vital step toward a fundamental understanding of the degradation behavior of PC lipid membranes in the presence of these clinically relevant enzymes, and toward the rational design of diagnostic and drug delivery technologies for phospholipase-dysregulation-based diseases

Fate of Liposomes in the Presence of Phospholipase C and D: From Atomic to Supramolecular Lipid Arrangement

Understanding the origins of lipid membrane bilayer rearrangement in response to external stimuli is an essential component of cell biology and the bottom-up design of liposomes for biomedical applications. The enzymes phospholipase C and D (PLC and PLD) both cleave the phosphorus–oxygen bonds of phosphate esters in phosphatidylcholine (PC) lipids. The atomic position of this hydrolysis reaction has huge implications for the stability of PC-containing self-assembled structures, such as the cell wall and lipid-based vesicle drug delivery vectors. While PLC converts PC to diacylglycerol (DAG), the interaction of PC with PLD produces phosphatidic acid (PA). Here we present a combination of small-angle scattering data and all-atom molecular dynamics simulations, providing insights into the effects of atomic-scale reorganization on the supramolecular assembly of PC membrane bilayers upon enzyme-mediated incorporation of DAG or PA. We observed that PC liposomes completely disintegrate in the presence of PLC, as conversion of PC to DAG progresses. At lower concentrations, DAG molecules within fluid PC bilayers form hydrogen bonds with backbone carbonyl oxygens in neighboring PC molecules and burrow into the hydrophobic region. This leads initially to membrane thinning followed by a swelling of the lamellar phase with increased DAG. At higher DAG concentrations, localized membrane tension causes a change in lipid phase from lamellar to the hexagonal and micellar cubic phases. Molecular dynamics simulations show that this destabilization is also caused in part by the decreased ability of DAG-containing PC membranes to coordinate sodium ions. Conversely, PLD-treated PC liposomes remain stable up to extremely high conversions to PA. Here, the negatively charged PA headgroup attracts significant amounts of sodium ions from the bulk solution to the membrane surface, leading to a swelling of the coordinated water layer. These findings are a vital step toward a fundamental understanding of the degradation behavior of PC lipid membranes in the presence of these clinically relevant enzymes, and toward the rational design of diagnostic and drug delivery technologies for phospholipase-dysregulation-based diseases