An investigation of alkaline phosphatase enzymatic activity after electrospinning and electrospraying

Lesley C Onyekuru,Anabela Moreira,Jiazhe Zhang,Ukrit Angkawinitwong,Pedro F Costa,Steve Brocchini,Gareth R Williams

doi:10.1016/j.jddst.2021.102592

Lesley C Onyekuru, Anabela Moreira + Show 5 more

Open Access

https://doi.org/10.1016/j.jddst.2021.102592

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Abstract

The high target specificity and multifunctionality of proteins has led to great interest in their clinical use. To this end, the development of delivery systems capable of preserving their bioactivity and improving bioavailability is pivotal to achieve high effectiveness and satisfactory therapeutic outcomes. Electrohydrodynamic (EHD) techniques, namely electrospinning and electrospraying, have been widely explored for protein encapsulation and delivery. In this work, monoaxial and coaxial electrospinning and electrospraying were used to encapsulate alkaline phosphatase (ALP) into poly(ethylene oxide) fibres and particles, respectively, and the effects of the processing techniques on the integrity and bioactivity of the enzyme were assessed. A full morphological and physicochemical characterisation of the blend and core-shell products was performed. ALP was successfully encapsulated within monolithic and core-shell electrospun fibres and electrosprayed particles, with drug loadings and encapsulation efficiencies of up to 21% and 99%, respectively. Monoaxial and coaxial electrospinning were equally effective in preserving ALP function, leading to no activity loss compared to fresh aqueous solutions of the enzyme. While the same result was observed for monoaxial electrospraying, coaxial electrospraying of ALP caused a 40% reduction in its bioactivity, which was attributed to the high voltage (22.5 kV) used during processing. This demonstrates that choosing between blend and coaxial EHD processing for protein encapsulation is not always straightforward, being highly dependent on the chosen therapeutic agent and the effects of the processing conditions on its bioactivity.

Highlights

Interest in therapy using protein-based active ingredients has been rising steadily over the years
280 fibres (EFB) comprised of alkaline phosphatase (ALP) and Poly(ethylene oxide) (PEO) could be produced by blend electrospinning, with an average diameter of 236 ± 79 nm (Figure 2 a and b)
The ALP was dissolved in PBS, resulting in a solution much less viscous than the PEO solution, and when the two are combined for electrospinning the overall viscosity of the mixed solution will be somewhere between the two starting solutions

Summary

Introduction

Interest in therapy using protein-based active ingredients has been rising steadily over the years. Unlike most small molecule drugs, peptides and proteins act with high specificity towards their target, potentially decreasing adverse and systemic side effects [1]. The administration of protein-based therapeutic agents – biologics – is still associated with a number of limitations. Protein agent administration is usually performed parenterally. Since proteins have short half-lives in the circulation, repeated administrations are required to maintain adequate doses at the target site. This unstable nature of proteins, as well as their low ability to cross biological barriers, further hinder their therapeutic effect [3]

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