Microchamber Arrays Made of Biodegradable Polymers for Enzymatic Release of Small Hydrophilic Cargos

The encapsulation of small hydrophilic molecules and response to specific biological triggers in a controlled manner has become one of the significant challenges in biomedical research, in particular in the field of localized drug delivery and biosensing. This work reports the fabrication of free-standing microchamber arrays films made of biodegradable polymers for the encapsulation and enzymatically triggered release of small hydrophilic molecules. Polycaprolactone (PCL) microchamber arrays had been demonstrated to fully biodegrade within 5 hours of exposure to lipase from Pseudomonas cepacia (Lipase PS) at a concentration of 0.5mg/ml, with lower concentrations producing corresponding longer degradation times. The gradual process of deterioration was real-time monitored utilising laser Fraunhofer diffraction patterns. Additionally, small hydrophilic molecule 5(6)-carboxyfluorescein (CF) were loaded into PCL microchamber arrays in a dry state, however the substantial permeability of the PCL film led to the leaking of the dye molecules. Consequently, polylactic acid (PLA) was blended with PCL to reduce its permeability, enabling PCL-PLA blending (1:2 ratio correspondingly) microchamber arrays to trap the small hydrophilic molecule CF. PCL-PLA (1:2) microchamber arrays hold potential for the controlled release under the catalysis of lipase within 26 hours. Additionally, it is calculated that approximately 11 pg of CF dye crystals were loaded into individual microchambers of size of 10μm, indicating that the microchamber array films could yield a highly efficient encapsulation.