Dissolving pulp has been subjected to consecutive periodate/​chlorite treatments to afford 2,3-dicarbo­xyl cellulose (DCC, 1.02 mmol g–1 COOH). Subsequent nanofibrillation afforded stable nematic nf-DCC dispersions (average particle size 2.1 nm × 525 nm) at significantly lower energy input compared to TEMPO-oxidation. Acid-induced gelation triggered by extensive hydrogen bonding sets the ordered state and affords free-standing hydrogels that can be converted to highly transparent birefringent aerogels by scCO2 drying. Uniaxial compression of the obtained ultra-lightweight ductile nf-DCC aerogels down to 5% of their original volume intriguingly preserves nematic orientation and transparence. Simultaneously, strain hardening translates into exceptionally good mechanical properties, such as toughness at nearly zero Poisson’s ratio. Uniaxial compression has been furthermore demonstrated to be a facile and efficient means for converting nf-DCC aerogels of broad, multiscale pore size distribution into entirely micro/​mesoporous scaffolds of narrow size distribution at far-reaching preservation of porosity. Following this approach, thermally superinsulating nf-DCC aerogels (λ = 0.018 W m–1 K–1) have been prepared, whose intriguing mechanical properties, transparence, and nematic ordering bear great potential for other applications as well.

Thanks to their high biocompatibility and bioactivity, bioactive glasses are very promising materials for soft and hard tissue repair and engineering. Because bioactivity and specific surface area intrinsically linked, the last decade has seen a focus on the development of highly porous and/or nano-sized materials. This review emphasizes the synthesis of bioactive glass nanoparticles and materials design strategies. The first part comprehensively covers mainly soft chemistry processes, which aim to obtain dispersible and monodispersed nanoparticles. The second part discusses the use of bioactive glass nanoparticles for medical applications, highlighting the design of materials. Mesoporous nanoparticles for drug delivery, injectable systems and scaffolds consisting of bioactive glass nanoparticles dispersed in a polymer, implant coatings and particle dispersions will be presented.