Atomic Force Microscopy-based Apoptosis And The Preparation Of LB Films

Atomic force microscopy (AFM) is a surface imaging technique with 1nm resolution for biological sample, which operates by measuring the interacting forces between a probe and the sample. By AFM we have studied the induction of apoptosis LOVO cells with BTW and the preparation of Langmuir-Blodgett (LB) films.(1) BTW is a new betulinic acid derivatives distilled from baitouweng. At present there is a little literature about BTW, and the effects that BTW have on LOVO cells have not been reported. For the first time we have analyzed the anticancer effects of BTW in apoptosis by AFM, optical microscope, fluorescence microscopy, UV-Vis spectroscopy and FCM, which provides evidences for mechanism of BTW in anticancer. BTW significantly inhibited the growth of LOVO cells in dose-dependent manner by flow cytometric analysis. By optical microscope we found that LOVO cells grew longer after treated with BTW. And nuclear fragmentation was observed by fluorescence microscopy. AFM showed that the microvilli decreased in the early apoptotic cells; that membrane shrunk and membrane blebs appeared in the intermediate apoptotic cells; that the pseudopods broke and apoptotic bodies formed in the late apoptotic cells. After analyzing FCM and UV-Vis spectra we speculate that BTW binds with DNA and inhibits the synthesis of nucleic acid, that DNA is the target molecule for BTW.(2) Langmuir-Blodgett (LB) films are useful as a simplified model system of a biological membrane. The reported LB films are made not according to the ratio of biological membrane constituents. And LB films with defects have not been reported. For the first time we have prepared special LB films which resemble the normal cell membrane and pathologic cell membrane. In the case of pure DPPC system and mixed DPPC/ cholesterol [C(DPPC):C(cholesterol)=2.6:1], phase-separated LB films were made deposited at LC-LE phase coexist which resemble the normal cell membrane. In the case of mixed DPPC/cholesterol [C(DPPC):C(cholesterol) =2.6:1],...