Search Results (3)

Background: With the evolving paradigm of vaccine development, microcapsules have attracted considerable research interest as particulate adjuvants over the past decades. However, the rational engineering design of microcapsule-based composite adjuvant systems to elicit robust immune responses remains a significant challenge. Methods: This study developed polylactic acid (PLA) microcapsules with spatiotemporally coupled delivery and immunopotentiator properties. The resulting formulations were assessed for humoral and cellular immune responses in mice. Results: We prepared uniform-sized microcapsules (MC) and formulated them with monophosphoryl lipid A (MPLA) as a composite component (MPLA@MC), with hydrodynamic diameters of 4.58 μm and 4.12 μm, respectively. Such composite adjuvants, when loaded with ovalbumin (OVA) to form OVA@MC and OVA&MPLA@MC, promoted cellular uptake and activation, exhibiting preferred lysosomal escape advantages. For in vivo experiments, microcapsule-based vaccines elevated serum levels of IgG antibody, and OVA&MPLA@MC induced Th1-biased antibody responses. Specifically, OVA&MPLA@MC also elicited strong cellular immune responses compared to other vaccines, as evidenced by increased secretion of Interferon-γ (IFN-γ) in mouse splenocytes and Granzyme B (Gzmb) in T cells. Mechanistically, muscle tissues at the injection site showed that microcapsule-based vaccines enhanced the recruitment for phagocytosis. Meanwhile, bulk RNA sequencing (RNA-seq) confirmed extensive activation of immune responses and related signaling pathways. Conclusions: This rationally designed composite strategy for spatiotemporally coupled delivery serves as a potent platform for orchestrating synergistic immune responses, opening up new avenues for the development of effective therapeutic and anti-infectious vaccines. Full article

Active-compound encapsulation in polymeric carriers is a widely used technology as it protects and improves the physical characteristics of the active compound and controls its delivery. The effectiveness of polymeric microcapsules (MCs) depends on the barrier properties of the polymeric shell; for a given polymer, the latter properties are affected by its molecular weight (MW) and crystallinity (x_c). The aim of this study was to modify the MW and x_c of the MCs shell via solid state polymerization (SSP). SSP may take place in the amorphous regions of the polymer upon heating at temperatures higher than the glass transition point (T_g) but lower than the onset of melting (T_m). Poly(lactic acid) (PLA) was chosen as the polymeric carrier and coumarin 6 as the encapsulated compound. PLA is a biobased and biodegradable polymer that is widely used in drug delivery systems, and coumarin 6 is a fluorescent hydrophobic drug that can be used as model compound. The effectiveness of SSP as a post-encapsulation tool was proven for blank PLA MCs of two molecular weights (MW = 50,000 g mol⁻¹ and 20,000 g mol⁻¹). SSP led to a 40–50% enhancement of the weight-average molecular weight of the polymeric shell and to an enhancement, from 40% to up to 70%, of the mass fraction crystallinity in the case of the low-MW MCs. In an attempt to transfer the gained knowledge to the encapsulation systems, coumarin-6-loaded MCs were prepared. The average size of the MCs was measured at 502 nm with a polydispersity index of 1.6 while the encapsulation efficiency was found to be 15% for a drug loading of 10%. UV–Vis measurements showed that the compound was fully released after 10 days. Coumarin 6 was found to be thermally stable at temperatures used for SSP, while the study of SSP application in the case of loaded MCs is in progress. Full article

In recent years, there has been an increasing need for materials that are environmentally friendly and have functional properties. Polylactic acid (PLA) is a biomass-based polymer, which has attracted research attention as an eco-friendly material. Various studies have been conducted on functionality imparting and performance improvement to extend the field of application of PLA. Particularly, research on natural fiber-reinforced composites have been conducted to simultaneously improve their environmental friendliness and mechanical strength. Research interest in hybrid composites using two or more fillers to realize multiple functions are also increasing. Phase change materials (PCMs) absorb and emit energy through phase transition and can be used as a micro encapsulated structure. In this study, we fabricated hybrid composites using microcapsulated PCM (MPCM) and the natural fibrous filler, kenaf. We aimed to fabricate a composite material with improved endothermic characteristics, mechanical performance, and environmental friendliness. We analyzed the endothermic properties of MPCM and the structural characteristics of two fillers and finally produced an eco-friendly composite material. The PCM and kenaf contents were varied to observe changes in the performance of the hybrid composites. The endothermic properties were determined through differential scanning calorimetry, whereas changes in the physical properties of the hybrid composite were determined by measuring the mechanical properties. Full article