Enzyme entrapment in confined micro-environments is an immobilization technique that allows recovery and re-use of the homogeneous catalyst without the need for chemically binding the enzyme molecule to a solid support. In this work, we demonstrate a novel one-step encapsulation of acid phosphatase enzyme within polyamine/silica composite microcapsules (~1-10 µm). In brief, addition of multivalent anions (e.g., Citrate3-) induces cationic polyamines to form short-lived spherical aggregates by way of salt-bridging. Addition of negatively charged nanoparticles (e.g., silica nanoparticles) to these aggregates leads to the formation of robust microcapsules with multi-nanoparticle layer thick shell wall (Rana et al., Adv. Mater. 2005, 17(9), 1145-1150). The enzyme can be easily introduced inside the microcapsules by combining with the polyamine/salt aggregate suspension before shell formation. Catalytic activity of acid phosphatase was observed through in situ time-lapse confocal microscopy. Fluorescein diphosphate (FDP) substrate (non-fluorescent) diffuses inside the microcapsule, and turns highly fluorescent upon catalytic cleavage of the phosphate groups. We discuss the quantitative aspects of enzyme encapsulation such as encapsulation efficiency and enzymatic activity.

Extended Abstract Status: Not Uploaded