ABSTRACT
Polyacrylic acid was firstly grafted by N-amino-4-N-methylpiperazine-1,8-naphthlimide (AMN) to prepare a amphiphilic polymer, which was self-assembled in water producing nanoparticles called as PAAMN.Then the morphology, structure and fluorescence properties of PAAMN were investigated by various methods including transmission electron microscopy, dynamic light scattering, ultraviolet-visible spectroscopy (UV-Vis), nuclear magnetic resonance spectroscopy (HNMR) and fluorescence spectroscopy.MTT assay was carried out to assess the cell compatibility of PAAMN.Finally, the fluorescence from PAAMN self and HeLa cells incubated with PAAMN was observed by fluorescence microscope.The results revealed that PAAMN had spherical structure, in which naphthlimide fluorphores were immobilized in the polyacrylic acid matrix with the degree of substitution of 4.1%.Under the physiological pH condition, PAAMN excited at 390 nm could emit strong and stable fluorescence at 534 nm.In the range of pH 4.0-10.0, its excitation and emission wavelengths had no obvious change.The fluorescence intensity of PAAMN increased with the decrease of pH values, but the pH sensitivity of PAAMN was much lower than that of AMN.PAAMN had good cell compatibility.From the pictures of fluorescence imaging, it was found that both PAAMN self and cells-engulfed PAAMN could emit green fluorescence upon excited at 390 nm, indicating the potential of the developed nanoparticle for cell imaging.
ABSTRACT
[Objective To explore the effect of problem-based learning(PBL) in biochemistry teaching in medical college. Methods Totally 128 students(2011 grade) of medical laboratory major were derived into experiment group(n=64)and control group(n=64). Lecture-based learning(LBL) was used in control group and PBL was used in experiment group.In control group,teachers did teaching design according to the needs of curriculum standards,employed multimedia courseware,explained the basic content of each chapter,class exercises and homework after class. In experimental group,PBL was conducted through establishing biochemistry teaching website based on school's teaching platform. Teach-ing process in experiment group included:grouping-selecting appropriate cases-consulting data-group discussing-summarizing by teachers. Theory test was carried out after the course and questionnaire was conducted for students in experiment group . Data were analyzed using the independent sample t test . Results Average test scores were higher in PBL group than in traditional group,with statistically signif-icant differences[(83.15±11.87)vs. (76.15±12.48)]. Questionnaire survey showed that more than 90.0%students in experiment group were interested in the PBL teaching method and thought that the PBL teach-ing method can enhance the enthu-siasm of learning, independent learning ability and comprehensive analysis ability. Conclusions PBL teaching method can improve the quality and the effect of biochemi-stry teaching and culture students' comprehensive ability. It is worthy of further study and popularization.