Montmorillonite colloid plates with adsorbed cytochrome c: in vitro cytotoxic effect on colon cancer cell culture

Background The apoptosis (a cascade of biochemical reactions leading to suicide of damaged biological cells) is blocked in the cancer cells because of impossibility of cytochrome c (cytC) go out from the mitochondria. However, the apoptosis can be started by introducing of exogenous cytC into cytoplasm using colloid particles as a protein carrier due to ability of the cancer cells to phagocytize extracellular particles with submicron size. Results The clay mineral montmorillonite (MM) were used to prepare aqueous suspension of protein/mineral composite particles by electrostatic adsorption of the positively charged cytC globules on the negatively charged MM colloid plates, and then added to colon cancel culture. The results shows out that separately cytC and MM have no effect but the composite cytC-MM particles kill 95% of the cancer cells after 96 h treatment using equine cytC which is 97% structurally identical with the human cytC. To reach this high cytotoxicity we have formulated requirements to: (a) bare colloid particles (electric charge, form and size), (b) conditions for protein adsorption (concentrations, pH, ionic strength), and (c) suspension with the composite particles (positive total charge and optimal concentration). Due to satisfying these requirements we have reached cytotoxicity which is 1/3 higher than the reached by other authors using different artificial particles. The cytotoxicity rapidly increases with concentration of the cytC-MM particles but further it shows tendency to saturation. Methods The optimal pH 6.5 and the 10:3 mg/mg cytC/MM concentration ratio at adsorption were found out by employing computer (protein electrostatics) and physicochemical methods (microelectrophoresis and colloid electrooptics) to prepare cytC-MM suspension. The anticancer capability of cytC-MM nanoplates were investigated using cell culture of metastasizing colon cancer. Conclusion The in vitro experiments with colon cancer cell culture disclose that cytC-MM composite particles have potential for application in anticancer therapy of superficial neoplasms of the skin and the alimentary system (mouth cavity, esophagus, stomach, jejunum and colon). Graphic abstract

High Nanopore Volume Tetrethoxysilane Based Aerogels Prepared with Addition of N, N-Dimethylformamide at Different Stage of the Sol-Gel Process

Using tetraethoxysilane (TEOS) as a precursor, silica aerogels were synthesized via the sol-gel polymerization followed by supercritical drying process. During the polymerization period, N, N-dimethylformamide (DMF), acting as a chemical additive for the structure control, was introduced in the hydrolysis step and condensation step, respectively. As a result, the nanopore volumes for the pores smaller than 100 nm were up to 6.0 cm3/g and 5.7 cm3/g for the samples that produced with DMF addition in the hydrolysis step and condensation step, while the value for the sample without DMF was only 4.6 cm3/g. Besides, the sample with DMF addition in the condensation step possessed more uniform pore size distribution while compared with that with DMF addition in the hydrolysis step. DMF can provide a shielding layer around the colloid particles through hydrogen bonds, inhibiting the aggregation of colloid particles and the enlarging of pore sizes.

Derived high reducing sugar and lignin colloid particles from corn stover

Lignocellulosic biomass is considered as the largest potential candidate to develop alternative energy, such as biofuel, biomaterial. However, the efficient conversion of cellulose and practical utilization of lignin are great challenges for sustainable biorefinery. In this study, high reducing sugar yield and different size of lignin colloid particles (LCPs) were obtained via tetrahydrofuran–water (THF–H2O) pretreatment of corn stover (CS). THF–H2O as a co-solvent, could efficiently dissolve lignin and retain cellulose. After the pretreatment, 640.87 mg/g of reducing sugar was produced, that was 6.66-fold higher than that of the untreated CS. Meanwhile, the pretreatment liquor could form spherical LCPs with different sizes ranged from 202 to 732 nm through self-assembly. We studied the optimal pretreatment condition to simultaneously realize the high reducing sugar yield (588.4 mg/g) and excellent LCPs preparation with average size of 243 nm was under TH22 (THF–H2O pretreatment at 120 °C for 2 h). To further explore the formation of LCPs with different sizes. We studied the lignin structure changes of various conditions, concluded the size of LCPs was related to the lignin concentration and syringyl/guaiacyl (S/G) ratio. As the increase of the lignin concentration and S/G, the sizes of LCPs were increased. G-type lignin was easier to dissolve in the mild pretreatment supernatant, contributing to form smaller LCPs with a good dispersibility. In the severe condition, both of S and G-type lignin were dissolved due to the lignin depolymerization, formed the larger sphere particles. This work provides a novel perspective for the technical design of lignocellulosic biomass conversion.