Understanding tip‐enhanced Raman spectra of biological molecules: a combined Raman,SERS and TERS study

Although conventional Raman, surface‐enhanced Raman (SERS) and tip‐enhanced Raman spectroscopy (TERS) have been known for a long time, a direct, thorough comparison of these three methods has never been carried out. In this paper, spectra that were obtained by conventional Raman, SERS (on gold and silver substrates) and TERS (in ‘gap mode’ with silver tips and gold substrates) are compared to learn from their differences and similarities. Because the investigation of biological samples by TERS has recently become a hot topic, this work focuses on biologically relevant substances. Starting from the TER spectra of bovine serum albumin as an example for a protein, the dipeptides Phe–Phe and Tyr–Tyr and the tripeptide Tyr–Tyr–Tyr were investigated. The major findings were as follows. (1) We show that the widely used assumption that spectral bands do not shift when comparing SER, TER and conventional Raman spectra (except due to binding to the metal surface in SERS or TERS) is valid. However, band intensity ratios can differ significantly between these three methods. (2) Marker bands can be assigned, which should allow one to identify and localize proteins in complex biological environments in future investigations. From our results, general guidelines for the interpretation of TER spectra are proposed. Copyright © 2012 John Wiley & Sons, Ltd.     

Benzo­[i]­naphtho­[c,d]­bi­cyclo­[5.4.1]dodecan‐12‐one

In the title compound, penta­cyclo­[11.8.1.1^3,11.0^7,23.0^15,20]­tricosa‐3,5,7,9,11(23),15,17,19‐octaen‐22‐one, C₂₃H₂₀O, the bi­cyclo­[5.4.1]­dodecan‐12‐one moiety takes a rigid conformation in which the seven‐ and eight‐membered rings take chair and boat–boat forms, respectively. The mol­ecule has a non‐crystallographic mirror symmetry perpendicular to the benzene and naphthalene planes.     

Layered [3.3]Orthocyclophane Tricarbonylchromium Complexes

The preparation of the layered [3.3]orthocyclophane tricarbonylchromium mono- and bis complexes, 4 and 5 , are described. X-ray crystallographic analysis reveals the fact that the distances and the dihedral angle between the planes of the two benzo rings in mono complex 4 decrease as compared to those in 1 . This is due to the decrease in π electron density in one benzo unit.     

Analysis of Calving Events in Antarctic Ice Shelves Using Configurational Forces

Previous studies on the sensitivity of cracks in ice shelves with different boundary conditions, stress states and density profiles revealed the need for further analyses. As the transfer of boundary conditions from dynamic ice flow simulations to the linear elastic fracture analyses proved to be a critical point in previous studies, a new approach to relate viscous and elastic material behaviour is proposed. The numerical simulations are conducted using Finite Elements utilizing the concept of configurational forces. To show the applicability of the approach, a 2-dimensional plane stress geometry with volume loads due to the ice shelf flow is analyzed. The resulting crack path is compared to available crack paths from satellite images. (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

A Mucin-Based Bio-Ink for 3D Printing of Objects with Anti-Biofouling Properties

With its potential to revolutionize the field of personalized medicine by producing customized medical devices and constructs for tissue engineering at low costs, 3D printing has emerged as a highly promising technology. Recent advancements have sparked increasing interest in the printing of biopolymeric hydrogels. However, owing to the limited printability of those soft materials, the lack of variability in available bio-inks remains a major challenge. In this study, a novel bio-ink is developed based on functionalized mucin—a glycoprotein that exhibits a multitude of biomedically interesting properties such as immunomodulating activity and strong anti-biofouling behavior. To achieve sufficient printability of the mucin-based ink, its rheological properties are tuned by incorporating Laponite XLG as a stabilizing agent. It is shown that cured objects generated from this novel bio-ink exhibit mechanical properties partially similar to that of soft tissue, show strong anti-biofouling properties, good biocompatibility, tunable cell adhesion, and immunomodulating behavior. The presented findings suggest that this 3D printable bio-ink has a great potential for a wide range of biomedical applications, including tissue engineering, wound healing, and soft robotics.     

Spurious modes elimination for fractional differential equations

In this paper, the stability of fractional differential equations is addressed. A criterion for the identification of spurious modes is derived. Two techniques for the a posteriori elimination of the corresponding solution parts are presented. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)