Nanocrystalline TiO2 has been obtained by a sol-gel process by controlling the crystal size through the water/alkoxide ratio. Raman spectra of anatase nanocrystals with average sizes of 9.5–13.4 nm are reported and the correlation between the Raman band shape (peak position and linewidth) of the main feature at 144 cm−1 and the crystals dimension is discussed. While in this system a minor role is played by nonstoichiometry and pressure effects, a model based on the phonon confinement, which takes into account the size distribution as determined by the transmission electron microscopy images, correctly reproduces the Raman band shape change.

Antibacterial materials that prevent bacterial infections and mitigate bacterial virulence have attracted great scientific interests. In recent decades, the bactericidal polymers have been presented as promising candidates to combat bacterial pathogens, mainly based on the construction of bactericidal cationic polymers, functionalization with biocidal agents, and formation of bacterial-repelling layers. However, these established strategies have inherent disadvantages because they often overlook important features such as their biocompatibility and biosafety, especially for biomedical applications. In recent years, many efforts have been made focusing on the development of multifunctional antibacterial materials to meet the elaborate requirements for medical devices and public hygiene products. Herein the recent advances in developing multifunctional materials for their antibacterial activities together with other functions including "kill-and-release" capability, hemocompatibility, cell proliferation promoting properties, and coagulation promoting ability for wound dressing are highlighted. In addition, the outlooks on the remaining challenges that should be addressed in the field of multifunctional antibacterial materials are also described.

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During the heat treatment of an anatase nanocrystalline powder at a high temperature, the two processes of anatase-to-rutile (A → R) transformation and grain growth would occur simultaneously and affect each other. With decrease of the original anatase grain size, the A → R transformation temperature range became extended on both sides, which may be partially attributed to the prevention effect of grain growth on this transformation. On the other hand, the grain growth process could be significantly enhanced by the A → R transformation, which can be ascribed to the higher atomic mobility because of the bond breakage during the transformation.

PETG/PC/TPU polymer blend was prepared by mechanical blending. The mechanical properties of modified PETG/PC/TPU blend were characterized using a universal testing machine, and results were compared against two commercial thermoplastic products -Erkodur and Biolon. Blending modification improved the properties of PETG/PC/TPU. When blending ratio (wt%) was 70/10/20, PETG/PC/TPU exhibited optimal mechanical properties which exceeded those of Erkodur and Biolon. Tear strength was 50.23 MPa and elongation at break was 155.99%. Stress relaxation rate was 0.0136 N/s after 1 hour, which was significantly slower than Erkodur and Biolon (p<0.05). Water absorption rate was 0.57% after 2 weeks, which was significantly lower than Erkodur and Biolon (p<0.05).

Catheter-related infection is a great challenge to modern medicine, which causes significant economic burden and increases patient morbidity. Hence, there is a great requirement for functionalized surfaces with inherently antibacterial properties and biocompatibility that prevent bacterial colonization and attachment of blood cells. Herein, we developed a strategy for constructing polymer brushes with hierarchical architecture on polyurethane (PU) via surface-initiated atom-transfer radical polymerization (SI-ATRP). Surface-functionalized PU (PU-DMH) was readily prepared, which comprised of poly­(3-[dimethyl-[2-(2-methylprop-2-enoyloxy)­ethyl]­azaniumyl]­propane-1-sulfonate) (PDMAPS) brushes as the lower layer and antimicrobial peptide-conjugated poly­(methacrylic acid) (PMAA) brushes as the upper layer. The PU-DMH surface showed excellent bactericidal property against both Gram-positive and Gram-negative bacteria and could prevent accumulation of bacterial debris on surfaces. Simultaneously, the PU-DMH samples possessed good hemocompatibility and low cytotoxicity. Furthermore, the integrated antifouling and bactericidal properties of PU-DMH under hydrodynamic conditions were confirmed by an in vitro circulating model. The functionalized surface possessed persistent antifouling and bactericidal performances both under static and hydrodynamic conditions. The microbiological and histological results of animal experiments also verified the in vivo anti-infection performance. The present work might find promising clinical applications for preventing catheter-related infection.

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