Tuning structure of spent coffee ground lignin by temperature fractionation to improve lignin-based carbon nanofibers mechanical performance.

Fabricating lignin-based carbon nanofibers (LCNFs) with the lignin in spent coffee grounds (SCG) as raw material which are disposed as waste amounting to millions tons annual is benefit to promote economy and environmental protection. However, due to the heterogeneity and complex three-dimensional structure, the mechanic property is very poor. In this study, we propose a fractionating pretreatment method to overcome the above problems by regulating the structure of SCG lignin in which high-performance LCNFs were fabricated. On one hand, the linear structure of SCG lignin was optimized to fit the raw material of LCNFs by tuning the content of ß-O-4 and C5-substituted condensed phenolic compounds. On the other hand, the carboxyl as the hydrophilic groups was removed so as to promote the mixing of lignin and polyacrylonitrile (PAN, blending agent) in organic solvents. Additionally, the heterogeneity was reduced by screening large molecular weight SCG lignin with low polydispersity index (PDI). Fortunately, with 1:1 mass ratio of the above fractionated lignin and PAN as substrate, the LCNFs could reach to comparable mechanic properties with those of pure PAN CNFs. This work can provide a new way to not only promote the utilization of SCG lignin but also accelerate the development of LCNFs.

Curcumin may be a potential adjuvant treatment drug for colon cancer by targeting CD44.

Despite the considerable advances in treatment method development, the mortality rate related to colon cancer still ranks the fifth in all tumor-related diseases. Recently, there has been growing evidences supporting the existence of colon cancer stem cells (CSCs) might be one of the main causes for initiation, progression and recurrence of colon cancer. Curcumin has been shown to possess anticancer activities. It has also been suggested that curcumin was effective against colon CSCs by coupling with CD44, a robust marker and functional important molecule for colorectal CSC. In the present study, we confirmed that curcumin can inhibit the proliferation, colony formation, migration and tumor sphere formation of colon cancer cells. Results from real-time PCR and western blotting had suggested that curcumin could down-regulate the expression of CD44. Moreover, results from flow cytometry had further revealed that curcumin could decrease the proportion of CD44+ colon cancer cells. After the expression of CD44 had been knocked down by using siRNA, the inhibition effects of curcumin against CD44+ colon cancer cells were observed to be reduced significantly. Moreover, it had been observed that the cellular uptake of curcumin was significantly higher in CD44+ colon cancer cells. Results from flow cytometry had shown that curcumin could induce apoptosis in CD44+ colon cancer cells. Altogether, our results suggested that curcumin might be an adjuvant drug for the treatment of colorectal cancer by targeting CD44.