Surface modification of biodegradable polymer film by electrostatic atomization

• Main Author: Tan, Hooi Sim.
• Other Authors: Alfred Tok Iing Yoong
• Format: Final Year Project
• Language: English
• Published: 2009
• Subjects: DRNTU::Engineering::Materials
• Online Access: http://hdl.handle.net/10356/15338
• Institution: Nanyang Technological University

This final year project reports the study of surface modification of biodegradable Poly (lactide-co-glycolide) (PLGA) 75/25 films via a micro-surface modification technique, Electrostatic Atomization with respect to its physiochemical effects. Electrostatic atomization has been employed generally due to its distinctive properties for mono-dispersity of the primary droplets is achievable, high net charge on the surface of the generated droplets, controllable droplet size by adjusting the flow rate or electrical conductivity of the liquid to be electro-sprayed and most important it relatively cheap and easy to operate. As it has been previously reported with topologies modification at micro/nano scale, the increase of surface roughness and that symmetry and spacing between features plays a critical role in enhancing cell interaction and adhesion. On top of that it is also reported that distance between features increase, cell adhesion increases too, hence achieving mono-dispersed sprayed substrate is optimum. The objectives of this report is to investigate and optimize the Electrostatic Atomization parameters to alter the surfaces of PLGA films and obtain mono-dispersed spray substrate for tissue engineering purpose in terms of cell adhesion and proliferation. Various parameters of EA for its voltage, flow rate, spraying time and copper ring distance from substrate were adjusted and optimized to obtained mono-disperse spray substrate. On top of that, other factor was also employed like atomizing with different solvent to test the effectiveness of creating desired surface profile. SEM and AFM results have shown that Electrostatic Atomization in cone jet mode with Dichloromethane (DCM) solution and polymeric solution containing (PLGA 75/25 and DCM) (1:100) are effective in creating mono-dispersed crater-like surface topographies on PLGA films. Results have shown that at a voltage of 4±0.5KV, DCM solution spray with a flow rate of 0.5ml/hr and substrate 2cm away from the copper ring has been observed to be the optimum parameters to produces the most mono-dispersed spray substrate. Whereas for PLGA: DCM (1:100), flow rate of 0.4ml/hr and 0.3ml/hr at substrate to copper of 1cm and 2cm respectively were found to be to be best operating parameters to obtain a mono-dispersed modified substrate.