Confined Multiple Enzymatic (Cascade) Reactions within Poly(dopamine)-based Capsosomes

Abstract

The design of compartmentalized carriers as artificial cells is envisioned to be an efficient tool with potential applications in the biomedical field. The advent of this area has witnessed the assembly of functional, bioinspired systems attempting to tackle challenges in cell mimicry by encapsulating multiple compartments and performing controlled encapsulated enzymatic catalysis. Although capsosomes, which consist of liposomes embedded within a polymeric carrier capsule, are among the most advanced systems, they are still amazingly simple in their functionality and cumbersome in their assembly. We report on capsosomes by embedding liposomes within a poly(dopamine) (PDA) carrier shell created in a solution-based single-step procedure. We demonstrate for the first time the potential of PDA-based capsosomes to act as artificial cell mimics by performing a two-enzyme coupled reaction in parallel with a single-enzyme conversion by encapsulating three different enzymes into separated liposomal compartments. In the former case, the enzyme uricase converts uric acid into hydrogen peroxide, CO2 and allantoin, followed by the reaction of hydrogen peroxide with the reagent Amplex Ultra Red in the presence of the enzyme horseradish peroxidase to generate the fluorescent product resorufin. The parallel enzymatic catalysis employs the enzyme ascorbate oxidase to convert ascorbic acid into 2-L-dehydroascorbic acid.

Subcompartmentalized Nanoreactors as Artificial Organelle with Intracellular Activity

“…The homogenous fluorescence, due to the presence of PLL F , confirmed that the PDA layer was thin enough to not entirely block the fluorescence emission. This aspect was important since we have prior observed that thick layers of PDA could entirely hinder the visualization of fluorescently labeled underlying layers . Furthermore, the particles remained well dispersed without aggregation, which was also supported when considering the flow cytometry histogram using particles suspended in HEPES 2 buffer (Figure c).…”

“…Subcompartmentalized systems have been fabricated using predominantly a combination of liposomes, polymersomes, and polymer capsules as building blocks . Among the most advanced approaches are polymersomes in polymersomes and capsosomes, liposomes within polymer carrier capsules, including the demonstration of encapsulated enzymatic cascade reactions as the most complex functionality in both cases. Janus microreactors, toward the mimicry of the polarity of cells, were recently reported .…”

Liposomal Drug Deposits in Poly(Dopamine) Coatings: Effect of Their Composition, Cell Type, Uptake Pathway Considerations, and Shear Stress

“…Specifically, we have reported the trapping of structurally intact liposomes in PDA-based films on planar [16b][17c] and colloidal substrates. [18] Recently, microneedles coated with a liposome-containing film were successful used in vivo toward non-invasive vaccine delivery applications by loading the liposomes with a protein antigen. [19] However, detailed fundamental insight into the interaction between liposome-containing films and adhering cells remains scares.…”

The concept of photochemical enzyme models – State of the art

“…The combination of several enzymatic transformations in concurrent onepot processes (multi-enzymatic cascade reactions) also plays an important role in biotechnology and modern synthetic chemistry [238,239]. In this context, attempts are also made to establish simple model systems for mimicking metabolism-like substrate transformations using multiple enzymatic cascade reactions in chemical environments resembling artificial cell structures [240].…”