1. Reporter : Chang-Fu Lain Professor: Cheng-Ho Chen Date : 6/11

2. Outline  Introduction  Materials  Experimental  Results and discussion  Conclusions

3. Introduction Electrospinning can be used to prepare polymeric fibers with diameters ranging from a nanometer to a micrometer scale, for any polymer soluble in a volatile solvent. Electrospinning is a powerful technique for the generation of polymeric fibers in the sub-micrometer scale, ranging from about 50 nm to several μm.

4. Introduction Electrospun polymer fibers can be: nano-sensors, military protective clothing, cosmetic skin masks, tissue engineering scaffolding, filter media, other industrial applications, and application in life science. Cellulose acetate (CA) material to produce nano and micrometric fibers with possible applications in tissue engineering, controlled release of drugs and as a bactericide, or membranes to the removal of Pb, toxic metallic pollutant from different aqueous samples.

5. Introduction PVP for the development of nano-fibers with applications in microencapsulation, for the controlled release of drugs and for chemical and biological sensors, hydrogels for articular cartilage replacement.

6. Introduction Highlights 1.Fibrous composite membranes of CA and PVP were prepared via electrospinning. 2.Their morphology, FTIR, and mechanical characterization were analyzed. 3.Tubes of CA with diameters around 500 nm were obtained. 4.The effect of pH on the release of amoxicillin was studied.

7. Outline  Introduction  Materials  Experimental  Results and discussion  Conclusions

8. Materials 1.cellulose acetate (CA, white powder, 39.7 wt.% acetyl content, average M n = 50,000 ) 2.Poly(vinyl-pyrrolidone) (PVP, white powder, average M w = 360,000) 3.Acetone 4.Ethanol 5.Amoxicillin 6.Sodium phosphate 7.Sodium hydroxide 8. Citric acid

9. Outline  Introduction  Materials  Experimental  Results and discussion  Conclusions

10. Experimental 1.CA, an acetone–water mixture + PVP fibrous membranes in an ethanol–water mixture (8% W) 2.A plastic syringe of 10 ml capacity together with a syringe pump kds Cientific.( flow velocity 0.3–1.5 ml h −1 ). 3.15 kV was applied to the polymer solution 4.The distance between the needle and the collector plate was set at 15 cm. 5. A square plate of aluminum (10 cm × 10 cm) was used as a collector.

11. Fig. 1. Configuration of the coaxial needles: the internal needle was connected to the syringe containing the polymer that was expected to be at the center of the fiber and the external needle was connected to the syringe containing the polymer supposed to be on the fiber surface.

12. 6.PVP was in the center of the tube and covered with CA, then, the composite microfiber was washed in order to dissolve the PVP in water to obtain microtubes of CA (Method I, M1 CA/PVP/CA). 7.Microfibers containing PVP at the surface and CA in the center were made (Method II, M1 PVP/CA/PVP), with the aim of comparing their morphology (diameter) with the fibers described above. 8. The fibers CA/PVP/CA and PVP/CA/PVP were washed with distilled water for 12 h, dry at room temperature for 12 h. Table 1 shows the conditions used in the preparation of the fibrous membranes. Table 1 9.SEM imaging 10.FTIR characterization 11.Mechanical analysis 12.Trapping of the drug in the matrix polymer 13.Effect of pH on the controlled release of amoxicillin Experimental

14. Outline  Introduction  Materials  Experimental  Results and discussion  Conclusions

15. Fig. 3. SEM micrographs for the fibrous membranes *CA/PVP/CA (a) before and (b) after washing them with water. Fibrous membranes *PVP/CA/PVP (c) before and (d) after washing them with water.

16. Fig. 4. TEM micrographs for the fibrous membrane *CA/PVP/CA (a) before and (b) after washing them with water.

17. Fig. 5. FTIR spectra of: (a) *CA, (b) *PVP, (c) *CA/PVP/CA before and (d) after washing them with water (e) amoxicillin, (f) *CA/PVP/CA membrane loaded with amoxicillin before freeze-drying, and (g) *CA/PVP/CA membrane loaded with amoxicillin after freeze-drying.

19. Fig. 6. SEM micrographs for the fibrous membranes *CA/PVP/CA with amoxicillin (a) before and (b) after freeze-drying process.

20. Fig. 7. Amoxicillin amount released from membrane *CA/PVP/CA at pH 3 and pH 7.2.

21. Outline  Introduction  Materials  Experimental  Results and discussion  Conclusions

22. Conclusions Via electrospinning were found, and their morphology, FTIR, and mechanical properties were characterized. The effect of the pH on the controlled release of amoxicillin was also studied. Nanotubes of CA with diameters around 500 nm were obtained. It was found that the release behavior of the drug from these fibrous membranes was dependent on the pH of the medium.

23. It was observed that amoxicillin time release was around 15 days and that the release at pH = 7.2 is three times higher than at pH = 3.0. These results suggest the existence of a greater number of possible interactions of amoxicillin with the components of the membrane at pH 3.0, attributed to the formation of hydrogen bonding, resulting in lower drug release. Conclusions

24. Thanks for your attention