Softwood bleached kraft pulp (SBKP) and microcrystalline cellulose (MCC) were oxidized using a 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated system. The TEMPO-oxidized SBKP prepared with 10 mmol/g NaClO (SBKP-10) had a higher mass recovery ratio and higher carboxylate content than the other prepared celluloses including the TEMPO-oxidized MCCs. The SBKP-10 was then exposed to cavitation-induced forces through sonication in water for 10-120 min to prepare aqueous dispersions of needle-like TEMPO-oxidized cellulose nanocrystals (TEMPO-CNCs) with homogeneous width of 3.5 to 3.6 nm and average lengths of ∼200 nm. The average chain lengths of the cellulose molecules that make up the TEMPO-CNCs were less than half the average lengths of the TEMPO-CNCs. Compared with conventional CNCs prepared by acid hydrolysis, the TEMPO-CNCs prepared by the acid-free and dialysis-free process exhibited higher mass recovery ratios, significantly higher amounts of surface anionic groups, and smaller and more homogeneous widths.

A bicrystalline titanium dioxide nanofiber with enhanced photocatalytic activity was synthesized from potassium titanate K 2 Ti 2 O 5 via ion exchange and calcination. The nanofiber has a core-shell crystalline structure with a thin TiO 2 (B) phase sheathing the anatase core, as characterized by X-ray diffraction, Raman spectroscopy, and high-resolution transmission microscopy (HRTEM). From HRTEM and local electron diffraction patterns, the two crystalline phases form a coherent interface with the 0.34-nm spacing between the (102) planes of TiO 2 (B) matching that between the anatase (101) lattice planes. The core-shell anatase/TiO 2 (B) nanofiber shows enhanced photocatalytic activity in iodine oxidation reaction with a 20-50% increase in extent of reaction compared to either single-crystal anatase or single-crystal TiO 2 (B) nanofibers. Anatase and TiO 2 (B) have the same band gap value of 3.2 eV, while theoretical calculations show the conduction band (CB) and valence band (VB) energies in anatase are both lower than the corresponding CB and VB energies in TiO 2 (B). The enhanced photocatalytic property may be due to enhanced and concerted charge mobility toward or away from the anatase/TiO 2 (B) interface. The special structure-property relationship can provide a new strategy to design and fabricate efficient photocatalytic and photovoltaic materials.

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Photosensitizer-based photodynamic therapy (PDT) can not only kill tumor cells by the generated cytotoxic reactive oxygen species (ROS), but also trigger immunogenic cell death (ICD) and activate immune response for...

A two-pronged approach combining photodynamic therapy and blockade of epithelial–mesenchymal transition in a minimalist nanoplatform was proposed to combat metastasis of basal-like breast cancer.

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