Zhang, Z;
J. R. Wells, C;
Davies, G-L;
Williams, GR;
(2021)
The effect of formulation morphology on stimuli-triggered co-delivery of chemotherapeutic and MRI contrast agents.
International Journal of Pharmaceutics
, 609
, Article 121155. 10.1016/j.ijpharm.2021.121155.
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Abstract
Most conventional chemotherapeutics have narrow therapeutic windows, and thus their delivery remains challenging and often raises safety and efficacy concerns. Theranostic platforms, with simultaneous encapsulation of therapeutic and diagnostic agents, have been proposed as next-generation formulations which can overcome this issue. In this work, we fabricated core@shell formulations comprising a pH responsive Eudragit L100 shell embedded with superparamagnetic iron oxide nanoparticles (SPIONs), and a thermo-responsive poly(N-isopropylacrylamide) (PNIPAM)/ethyl cellulose core loaded with the model drug carmofur. The key aim was to explore the effect of morphology (particles/fibres) on stimuli-responsive release. By varying the weight ratio of core polymer to shell polymer, the morphology of PNIPAM/ethyl cellulose@Eudragit L100 microparticles changed from concave microparticles to spherical particles. Smooth cylindrical fibres could also be generated. All the formulations exist as amorphous solid dispersions of drug-in-polymer, with distinct core@shell architectures. The fibres have clear thermo-responsive drug release profiles, while no thermo-responsive properties can be seen with the particles. All the formulations can protect SPIONs from degradation in gastric fluids (pH ∼ 1.5), and around the physiological pH range the materials offer effective and pH-responsive relaxivity. The r2 values also display clear linear relationships with drug release data, suggesting the potential of using MRI signals to track drug release in vivo. Mathematical equations were established to track drug release in vitro, with very similar experimental and predicted release profiles obtained.
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