No abstract

This work is to fabricate thermo responsive nanofibers of which the thermo response temperatures could be easily tuned, and of which the fibrous shapes could be maintained after heating-cooling cycles in aqueous solution. The nanofibers were further fabricated into a nonwoven mat with size-variable pores for temperature controlled release of a model drug, Erlotinib. The thermo responsive nanofibers were electrospun from the copolymers of PMMA-co-PVCL (synthesized from MMA and PVCL, and had different LCSTs) by changing the solvents and the ratio of initiator/monomer. FT-IR and 1 H NMR were used for molecular structural characterization; UV-vis spectra were used for LCST measurement; SEM and metalloscope were used to determine the optimal electrospinning parameters and to observe the shape maintaining abilities of the nanofibers after the heating-cooling recycles. Then, anti-cancer drug, Erlotinib, was incorporated into PMMA/PVCL nanofibers (represent as 'model I'), or put in a drug reservoir and covered with the PMMA/PVCL electrospinning mat (presented as 'model II'). UV-vis spectra were used to study the drug release behavior of each model. Results indicate that in model I, drug release was "switch on" below LCST, and "switch off" above LCST; in model II, drug release was faster above LCST than below LCST.

No abstract

In this paper, stearic acid/Zn 2þ monolayer were formed at airÀwater interface and then multilayers were deposited onto a glass slide by LangmuirÀBlodgett method. After annealing at 300 C for 0.25 h and 550 C for 2 h, ZnO thin¯lms were fabricated. The optimized parameters for monolayer formation and multilayers deposition were determined by the surface pressure-surface area (Å-A) isotherm and transfer ratio (t.r.), respectively. The results of X-ray di®raction showed that multilayers changed into ZnO thin¯lms with hexagonal structure and of high crystallization after annealing at high temperature. The observation of SEM images indicated that ZnO thin¯lms had a uniform and°at surface with compact arrangement.