Engineered CHT/VCO-based emulsion structures doped with photosensitive capsules: a functional carrier device

Drug carriers are the most effective vehicles for protecting and preserving therapeutic molecules during their release pathway. The design of carriers with stimulus-sensitive moieties would lead to the generation of ‘‘smart” delivery systems, allowing a temporal control of the drug release. As well ensuring the sustainable drug delivery, promoting low toxicity, high stability through cargo protection, and targeting efficiency. Those systems will allow the addressment of different biomedical and pharmaceutical applications, particularly in the treatment of local skin and systemic diseases [1-3].

This work proposes the employment of the Layer-by-layer (LbL) methodology to prepare hollow capsules loaded with curcumin (CUR). LbL assembly is a simple and highly versatile methodology to fabricate robust and highly-ordered nanostructured coatings over almost any substrate and employing a wide range of substances.

A polyoxometalate (POM) ([NaP₅W₃₀O₁₁₀]^14-) combined with a natural origin polymer, chitosan (CHT) was used to build up the multilayer system, being the POM responsible for a spatially controlled disruption of the assembled layers due to the weakening of the electrostatic interactions between them [4]. Thereby promoting capsule disruption and consequent content release [4]. The selection of the natural bioactive compound CUR relies on its antioxidant and wound healing properties [5], according to the envisioned application.

The capsules, with different sizes between 2-5µm (SEM), were further dispersed into CHT/VCO emulsion solutions that were casted into molds and dried at 37ºC for 48h.

The swelling, release profile, and antioxidant performance of the designed structures were further studied, revealing a synergistic beneficial effect resulting from CUR and VCO individual bioactivities.

In summary, the rational design and characterization of tailored, stimuli-responsive carriers and their subsequent stepwise screening for delivery efficiency and anti-oxidant activity opens routes for its potential application as a top-down approach yielding the best carrier system.

Acknowledgments: The authors especially acknowledge financial support from Portuguese FCT (SFRH/BPD/93697/2013 and CEECIND/01306/2018). Authors also acknowledge R&D&I Structured Project reference NORTE-01-0145-FDER-000021.

References:

1.            Costa, R.R., et al., Biomacromolecules, 2013. 14(7): p. 2403-2410.

2.            Lima, A.C., C. Alvarez-Lorenzo, and J.F. Mano, 2016. 5(14): p. 1687-1723.

3.            Ribeiro, C., et al., Molecules, 2018. 23(3).

4.            Rodrigues, L.C., et al., Journal of Materials Chemistry B, 2016. 4(8): p. 1398-1404.

5.            Maheshwari, R.K., et al., Life Sciences, 2006. 78(18): p. 2081-2087.