Surface-enhanced resonance Raman spectroscopy of porphyrin and metalloporphyrin species in systems with Ag nanoparticles and their assemblies.

The advantages of systems with Ag nanoparticles and their assemblies for surface-enhanced resonance Raman scattering (SERRS) spectral investigation, detection and determination of porphyrin species are demonstrated. SERRS spectral detection limits of the testing porphyrin species (including porphyrin aggregates) in these systems are shown to be, on average, 10(2)-10(3) lower than detection limits by resonance Raman scattering (RRS). Systems with Ag nanoparticles modified by anionic organosulfur spacers enable us to obtain SERRS spectra of unperturbed cationic porphyrin species.

Microdomain structure in polylactide-block-poly(ethylene oxide) copolymer films.

Structured surface is an important property of polymer biomaterials for tissue engineering, for its capacity to expose domains with different surface energy and functional groups. For this purpose, amphiphilic A-B-A block copolymers with polylactide (PLA) as A blocks and poly(ethylene oxide) (PEO 3, Mn = 3090; PEO6, Mn = 6110) as B block were synthesized by ring-opening polymerization of either L-lactide (L-LA) or DL-lactide (DL-LA), using poly(ethylene glycol)s as macroinitiators and tin(II) octanoate (Sn(Oct)2) as a catalyst. Differential scanning calorimetry (DSC) and electron microscopy were used to study the phase separation of the hydrophobic (PLA) and hydrophilic (PEO) segments in films made of the copolymers and their blends with high-molecular-weight PLA homopolymers.

Silicone rubber-hydrogel composites as polymeric biomaterials. III. An investigation of phase distribution by scanning electron microscopy.

The structure of silicone rubber-hydrogel composite materials was investigated by scanning electron microscopy (SEM) and light microscopy. The polymer phases in these materials composed of the polysiloxane matrix and very small particles of lightly cross-linked poly(2-hydroxyethylmethacrylate) or poly(2-hydroxyethylmethacrylate-co-methacrylic acid) were visualized using both methods. The distribution of polymer phases was studied by SEM of fracture surfaces of the materials.