Forming nanospherical cellulose containers

Nanospherical cellulose containers (SCC) (average size, ∼50 nm) are prepared by the sonochemical method. Organic and water-soluble materials are encapsulated within the SCC using only microcrystalline cellulose (MCC), an organic solvent, and water. Using silicotungstic acid (H₄SiW₁₂O₄₀), the prepared SCCs can be catalytically converted (78 wt % conversion) to glucose (30 wt % glucose yield) by applying microwave irradiation for only 3 min. These results are attributed to the large increase of surface area of the cellulose sphere relative to MCC, and a better contact with the solid catalyst. Sealed in a vessel, SCCs were found stable for more than 6 months when stored at 4 °C or at room temperature. The encapsulation efficiency of the organic phase was measured and found to be approximately 90%. The creation of the sphere involves the degradation of the MCC to smaller fragments by high-intensity ultrasound irradiation, and the organization of these fragments in nanospheres involves the formation of bonds of the same type as those in regular cellulose (MCC). The structure and properties of SCCs were analyzed using high resolution scanning electron microscopy, Fourier transform infrared microscopy, ¹³C magic angle spinning NMR, X-ray diffraction, and fluorescence microscopy.