Raman spectroscopy can be used to measure the chemical composition of a sample, which can in turn be used to extract biological information. Many materials have characteristic Raman spectra, which means that Raman spectroscopy has proven to be an effective analytical approach in geology, semiconductor, materials and polymer science fields. The application of Raman spectroscopy and microscopy within biology is rapidly increasing because it can provide chemical and compositional information, but it does not typically suffer from interference from water molecules. Analysis does not conventionally require extensive sample preparation; biochemical and structural information can usually be obtained without labeling. In this protocol, we aim to standardize and bring together multiple experimental approaches from key leaders in the field for obtaining Raman spectra using a microspectrometer. As examples of the range of biological samples that can be analyzed, we provide instructions for acquiring Raman spectra, maps and images for fresh plant tissue, formalin-fixed and fresh frozen mammalian tissue, fixed cells and biofluids. We explore a robust approach for sample preparation, instrumentation, acquisition parameters and data processing. By using this approach, we expect that a typical Raman experiment can be performed by a nonspecialist user to generate high-quality data for biological materials analysis.

We present an unambiguous identification of low-frequency terahertz vibrations in the archetypal imidazole-based metal-organic framework (MOF) materials: ZIF-4, ZIF-7, and ZIF-8, all of which adopt a zeolite-like nanoporous structure. Using inelastic neutron scattering and synchrotron radiation far-infrared absorption spectroscopy, in conjunction with density functional theory (DFT), we have pinpointed all major sources of vibrational modes. Ab initio DFT calculations revealed the complex nature of the collective THz modes, which enable us to establish detailed correlations with experiments. We discover that low-energy conformational dynamics offers multiple pathways to elucidate novel physical phenomena observed in MOFs. New evidence demonstrates that THz modes are intrinsically linked, not only to anomalous elasticity underpinning gate-opening and pore-breathing mechanisms, but also to shear-induced phase transitions and the onset of structural instability.

Selective adsorption of SO2 is realized in a porous metal–organic framework material, and in‐depth structural and spectroscopic investigations using X‐rays, infrared, and neutrons define the underlying interactions that cause SO2 to bind more strongly than CO2 and N2.

The carotenoid species lutein, violaxanthin, and zeaxanthin are crucial in the xanthophyll-dependent nonphotochemical quenching occurring in photosynthetic systems of higher plants, since they are involved in dissipation of excess energy and thus protect the photosynthetic machinery from irreversible inhibition. Nonetheless, important properties of the xanthophyll cycle carotenoids, such as the energy of their S(1) electronic states, are difficult to study and were only recently determined in organic solvents [Polívka, T. (1999) Proc. Natl. Acad. Sci. U.S.A. 96, 4914. Frank, H. A. (2000) Biochemistry 39, 2831]. In the present study, we have determined the S(1) energies of three carotenoid species, violaxanthin, lutein, and zeaxanthin, in their LHCII (peripheral light-harvesting complex of photosystem II) protein environment by constructing recombinant Lhcb1 (Lhc = light-harvesting complex) proteins containing single carotenoid species. Within experimental error the S(1) energy is the same for all three carotenoids in the monomeric LHCII, 13,900 +/- 300 cm(-1) (720 +/- 15 nm), thus well below the Q(y)() transitions of chlorophylls. In addition, we have found that, although the S(1) lifetimes of violaxanthin, lutein, and zeaxanthin differ substantially in solution, when incorporated into the LHCII protein, their S(1) states have in fact the same lifetime of about 11 ps. Despite the similar spectroscopic properties of the carotenoids bound to the LHCII, we observed a maximal fluorescence quenching when zeaxanthin was present in the LHCII complex. On the basis of these observations, we suggest that, rather than different photochemical properties of individual carotenoid species, changes in the protein conformation induced by binding of carotenoids with distinct molecular structures are involved in the quenching phenomena associated with Lhc proteins.

During nuclear waste disposal process, radioactive iodine as a fission product can be released. The widespread implementation of sustainable nuclear energy thus requires the development of efficient iodine stores that have simultaneously high capacity, stability and more importantly, storage density (and hence minimized system volume). Here, we report high I2 adsorption in a series of robust porous metal–organic materials, MFM-300(M) (M = Al, Sc, Fe, In). MFM-300(Sc) exhibits fully reversible I2 uptake of 1.54 g g–1, and its structure remains completely unperturbed upon inclusion/removal of I2. Direct observation and quantification of the adsorption, binding domains and dynamics of guest I2 molecules within these hosts have been achieved using XPS, TGA-MS, high resolution synchrotron X-ray diffraction, pair distribution function analysis, Raman, terahertz and neutron spectroscopy, coupled with density functional theory modeling. These complementary techniques reveal a comprehensive understanding of the host–I2 and I2–I2 binding interactions at a molecular level. The initial binding site of I2 in MFM-300(Sc), I2I, is located near the bridging hydroxyl group of the [ScO4(OH)2] moiety [I2I···H–O = 2.263(9) Å] with an occupancy of 0.268. I2II is located interstitially between two phenyl rings of neighboring ligand molecules [I2II···phenyl ring = 3.378(9) and 4.228(5) Å]. I2II is 4.565(2) Å from the hydroxyl group with an occupancy of 0.208. Significantly, at high I2 loading an unprecedented self-aggregation of I2 molecules into triple-helical chains within the confined nanovoids has been observed at crystallographic resolution, leading to a highly efficient packing of I2 molecules with an exceptional I2 storage density of 3.08 g cm–3 in MFM-300(Sc).