Seven malonate derivatives of C60 with different addition number and regiostructure were obtained by the "one-pot" reaction of C60 with diethyl bromomalonate (1:6) and subsequent separation by silica gel chromatography. The corresponding malonic acid derivatives of C60 were formed by hydrolyzing with NaH and CH3OH. Four of them with different addition number (C60(C(COOH)2)n, n

To improve the blood compatibility of Bombyx mori silk fibroin (SF) film, the film was modified by SO2 gas plasma treatment, or by a two-step process including NH3 gas plasma treatment and reaction with 1, 3-propane sultone. XPS and ATR-FTIR were used to analyze the surface chemical elements. In vitro antithrombogenicity was determined by the method of the activated partial thromboplastin time (APTT), prothrombin time (PT) and thrombin time (TT) tests. Percents of sulfur element on the surfaces of both modified SF films were 4.03% and 3.30%, respectively, while that of the control film was only 0.32%. Moreover, the antithrombogencity of treated films was increased remarkably due to surface sulfonation. The results implied a potential use of sulfonated SF for blood-contacting biomaterials.

Synthesis of novel methanophosphonate and methanophosphonic acid C60 derivatives was achieved, and their cytotoxicity was studied. In particular, a bis-methanophosphonate C60 derivative displayed photo-induced cytotoxicity on HeLa cells with IC50 value of 1.30

Activities of trimalonic acid fullerene (TMA C60) on DNA restrictive enzymatic reaction were investigated by using two restrictive endonucleases Hind III and EcoR I and plasmid pEGFP-N1 with single restrictive site for both enzymes. Meanwhile, TMA C60 was also tested to clarify its effects on polymerase chain reaction (PCR) with the catalyst of Taq DNA polymerase and the template of plasmid pEGFP-N1. The products from restrictive reactions or PCR were detected by agarose gel electrophoresis. It was found that the product amounts from restrictive reactions or PCR decreased significantly with addition of TMA C60. The inhibition by TMA C60 was dose-dependent and IC50 values for reactions of Hind III, EcoR I and PCR were 16.3, 6.0 and 6.0 μmol/L, respectively. Addition of two scavengers of reactive oxygen species (ROS), L-ascorbic acid-2-phosphate ester magnesium and sodium azide at the concentrations of 2―10 mmol/L did not antagonize the activities of TMA C60 against PCR and two restrictive reactions. However, increase of Taq DNA polymerase amounts in PCR system antagonized the activities of TMA C60. These data implied that TMA C60 was able to inhibit the activities of the three above-mentioned enzymes involved in DNA metabolism, and that this inhibition probably did not correlate to ROS.

Photo-induced cytotoxicity of malonic acid [C60] fullerene derivatives and its mechanism X. L. Yang*, C. H. Fan, H. S. Zhu Research Center of Materials Science, Beijing Institute of Technology, PO Box 327, Beijing 100081, PR China Accepted 10 August 2001 The biological activities of fullerenes have attracted extensive attention in recent years. The aim of this paper is to study the relation of the photo-induced cytotoxicity of fullerene derivatives to their chemical structures as well as the possible cellular mechanism involved in the photocytotoxicity. Three C60 derivatives with two to four malonic acid groups (DMA C60, TMA C60 and QMA C60) were prepared and the cytotoxicity of these compounds against HeLa cells was determined by MTT. Cell cycle was measured by flow cytometry. The results showed that the cytotoxicity of the malonic acid C60 derivatives was irradiation-and dosedependent. The sequence of their photo-induced growth inhibition was DMA C60>TMA C60>QMA C60. Hydroxyl radical quencher mannitol (10mm) was not able to prevent cells from the damage induced by irradiated DMA C60. DMA C60,together with irradiation,was found to have an ability of inducing a decrease in the number of G1 cells from 63 to 42% and a rise in that of G2+M cells from 6 to 26%. These data indicated that the number of malonic acid molecules added to C60 played an important role in the phototoxicity and the blockage of cell cycle might be a mechanism of this activity.