Recent developments in the fabrication of core-shell polymer nanocapsules, as well as their current and future applications, are reported here. Special attention is paid to the newly introduced surfactant-free fabrication method of aqueous dispersions of nanocapsules with hydrophobic liquid cores stabilized by amphiphilic copolymers. Various approaches to the efficient stabilization of such vehicles, tailoring their cores and shells for the fabrication of multifunctional, navigable nanocarriers and/or nanoreactors useful in various fields, are discussed. The emphasis is placed on biomedical applications of polymer nanocapsules, including the delivery of poorly soluble active compounds and contrast agents, as well as their use as theranostic platforms. Other methods of fabrication of polymer-based nanocapsules are briefly presented and compared in the context of their biomedical applications.

Background: Vascular drug delivery becomes a promising direction in the development of novel therapeutic strategies in the treatment of cardiovascular pathologies, such as hypertension. However, targeted delivery of hydrophobic substances, with poor bioavailability, remains a challenge. Here, we described the hypotensive effects of a low dose of curcumin delivered to the vascular wall using hyaluronic acid-based nanocapsules. Methods: The group of hypertensive TGR(m-Ren2)27 rats, was administrated respectively with the vehicle, curcumin solution or curcumin delivered using hyaluronic acid-based nanocapsules (HyC12-Cur), for 7 days each, maintaining the wash-out period between treatments. Arterial blood pressure (systolic - SBP, diastolic – DBP) and heart rate (HR) were monitored continuously using a telemetry system (Data Science International), and Mean Arterial Pressure (MAP) was calculated from SBP and DBP. Results: In hypertensive rats, a low dose of curcumin (4.5 mg/kg) administrated in HyC12-Cur for 7 days resulted in a gradual inhibition of SBP, DBP and MAP increase without an effect on HR. At the end of HyC12-Cur – based treatment changes in SBP, DBP and MAP amounted to − 2.0± 0.8 mmHg, − 3.9± 0.7 mmHg and − 3.3± 0.7 mmHg, respectively. In contrast, the administration of a curcumin solution (4.5 mg/kg) did not result in a significant hypotensive effect and the animals constantly developed hypertension. Vascular delivery of capsules with curcumin was confirmed using newly developed fluorine-rich nanocapsules (HyFC10-PFOB) with a shell based on a HA derivative and similar size as HyC12-Cur. HyFC10-PFOB gave fluorine signals in rat aortas analyzed ex vivo with a ¹⁹F NMR technique after a single intragastric administration. Conclusion: These results suggest that nanocapsules based on hyaluronic acid, the ubiquitous glycosaminoglycan of the extracellular matrix and an integral part of endothelial glycocalyx, may represent a suitable approach to deliver hydrophobic, poorly bioavailable compounds, to the vascular wall.

Diallyl disulfide (DADS) and diallyl trisulfide (DATS) are garlic oil compounds exhibiting beneficial healthy properties including anticancer action. However, these compounds are sparingly water-soluble with a limited stability that may imply damage to blood vessels or cells after administration. Thus, their encapsulation in the oil-core nanocapsules based on a derivative of hyaluronic acid was investigated here as a way of protecting against oxidation and undesired interactions with blood and digestive track components. The nuclear magnetic resonance (¹H NMR) technique was used to follow the oxidation processes. It was proved that the shell of the capsule acts as a barrier limiting the sulfur oxidation, enhancing the stability of C=C bonds in DADS and DATS. Moreover, it was shown that the encapsulation inhibited the lysis of the red blood cell membrane (mainly for DADS) and interactions with serum or digestive track components. Importantly, the biological functions and anticancer activity of DADS and DATS were preserved after encapsulation. Additionally, the nanocapsule formulations affected the migration of neoplastic cells—a desirable preliminary observation concerning the inhibition of migration. The proposed route of administration of these garlic extract components would enable reaching their higher concentrations in blood, longer circulation in a bloodstream, and thus, imply a better therapeutic effect.

Introduction: As vitamin K₁ (phylloquinone, PK) displays vasoprotective effect, low dietary intake and poor bioavailability of PK may result in insufficient systemic levels for maintaining vascular health. This study aimed to test whether PK in hyaluronan-based nanocapsules (PK-Oil-HyC12) improves PK pharmacokinetics and endothelial function compared to PK in oil emulsion (PK-Oil). Methods: PK pharmacokinetics in plasma, liver and aorta were analysed after single, oral administration of PK (10 mg/kg) in oil (PK-Oil) or encapsulated in hyaluronan-based nanocapsules with oil core (PK-Oil-HyC12) in mice using liquid chromatography-tandem mass spectrometry with atmospheric pressure chemical ionization method. PK-Oil-HyC12 absorption and nanocapsules distribution in lymphatic system was determined using a cycloheximide-based chylomicron flow blockage and intravital confocal microscopy. The endothelial function was analyzed in vivo by MRI in mice with dietary PK deficiency after 7-day supplementation with PK-Oil or PK-Oil-HyC12 (0.5 mg PK/kg). Results: After a single, oral dose of PK-Oil-HyC12 in mice total exposure of PK (AUC values) was 2– 4 times higher as compared to PK-Oil in plasma and liver, with no difference in PK content in the aorta. The efficient absorption and distribution of nanocapsules occurred mainly via a chylomicron-independent lymphatic route. Importantly, 7-day PK-Oil-HyC12 supplementation restored impaired endothelium-dependent vasodilation in the aorta of PK-deficient mice, while PK-Oil was ineffective. Conclusion: The improved bioavailability of PK, when administered in the form of hyaluronan-based nanocapsules, afforded the rapid replenishment of systemic PK and the reversal of endothelial dysfunction induced by low PK levels.