Photodissociation Spectroscopy and Dissociation Dynamics of TiO+(CO2)

Mimicking the Architecture and Dissolution Chemistry of Cancellous Bone Tissue to Optimize the Biocompatibility of Bioactive Scaffolds

Synthesis of mechanically stable porous scaffolds with an architecture analogous to cancellous bone tissue poses significant challenges to bioactive glass (BG) based scaffolds. This is primarily due to densification and crystallization of the BG's during heat treatment. This study presents a modified BG series (42SiO2-xTiO2-24Na2O-21CaO-13P2O5, where x = 8 and 16 TiO2). TiO2 replaced the SiO2 concentration in the glass and was incorporated due to its biocompatibility and influence on glass structure. Material characterization determined that TiO2 did not induce crystallization within the glass but did increase the glass transition temperature (Tg) from 520°C to 600°C thereby indicating a more stable network connectivity. Scaffolds were synthesized using the foam replication method, resulting in scaffolds with a pore size of approximately 500 μm with the BG-4 composition (30SiO2-12TiO2-24Na2O-21CaO-13P2O5) retaining its amorphous character post-heat treatment. Scaffold ion release was monitored over 5-60 days in simulated body fluid (SBF). Si4+ release was found to decrease, while Ca2+ levels increased in SBF as TiO2 replaced SiO2 within the glass series. Cytocompatibility studies revealed that MC3T3 Osteoblast cells proliferated on the BG-4 scaffold surface and at its interface within culture media, and cell numbers were not significantly reduced.

UV-vis spectroscopy of gas-phase ions

Photodissociation action spectroscopy has made a great progress in expanding investigations of gas-phase ion structures. This review deals with aspects of gas-phase ion electronic excitations that result in wavelength-dependent dissociation and light emission via fluorescence, chiefly covering the ultraviolet and visible regions of the spectrum. The principles are briefly outlined and a few examples of instrumentation are presented. The main thrust of the review is to collect and selectively present applications of UV-vis action spectroscopy to studies of stable gas-phase ion structures and combinations of spectroscopy with ion mobility, collision-induced dissociation, and ion-ion reactions leading to the generation of reactive intermediates and electronic energy transfer.