Novel Low-Molecular-Weight-Gelator-Based Microcapsules with Controllable Morphology and Temperature Responsiveness

Low-Molecular-Weight Gels as Smart Materials for the Enhancement of Antioxidants Activity

Antioxidants are important substances used in the cosmetic and pharmaceutical fields that are able to block free radicals. These compounds can be incorporated into formulations for many reasons, such as release over time or preservation of the formulation activity and applicability. In the present study, a low-molecular-weight gel made with Boc-L-DOPA(Bn)2-OH was studied as suitable material to host antioxidants and improve their activity. The solvent change (DMSO/H2O) in combination with temperature was the technological procedure for the preparation of the gel. Two different antioxidants were tested: (1) α-tocopherol and (2) postbiotics. The antioxidant activity of α-tocopherol and of the postbiotics in the gel, measured by the (2,2-diphenyl-1-picryl-hydrazyl radical (DPPH) assay, showed higher values than those in the pure solvent. The antioxidant activity of the gel with 0.8 w/v% of gelator and α-tocopherol in the concentration range of 5–100 µM was 2.7–1.1 times higher on average than in the pure solvent. In the case of both postbiotics, the biggest difference was observed at 30% of postbiotics in the gel with 0.5% of a gelator, when the antioxidant activity was 4.4 to 4.7 times higher than that in the pure solvent.

Estimation of electron transfer properties of ferrocenyl-dicholesteryl-peptide in liquid and gel

Molecular dynamics simulations were carried out to investigate the conformations of ferrocenyl-dicholesteryl N-formamidoformamide (Fc-LS2) molecules in solvents of methanol and 1-propanol. Fc-LS2 comprises ferrocene and cholesteryl units linked by a biocompatible N-formamidoformamide peptide unit. Our results showed that Fc-LS2 formed a gel with 1-propanol but not with methanol. Charge-transfer properties of Fc-LS2/1-propanol gel and Fc-LS2/methanol liquid were also investigated by quantum mechanical (QM) calculations. The QM results indicate that the amino acid linkages contribute to improved charge-transport properties and the transfer integrals of Fc-LS2/1-propanol are larger than those of Fc-LS2/methanol.

Surface-engineering of glycidyl methacrylated dextran/gelatin microcapsules with thermo-responsive poly(N-isopropylacrylamide) gates for controlled delivery of stromal cell-derived factor-1α

In situ tissue engineering has been proposed as a promising method to address the need for the clinical regeneration of a wide variety of damaged tissues. This approach comprises the use of a cell-free instructive scaffold that incorporates and releases topical chemotactic factors to recruit host endogenous stem/progenitor cells for tissue regrowth at the locus of implantation. However, the clinical translation of this concept is hampered when repeated doses of medication must be administrated over an extended period of time. In this study, we designed a delivery platform characterized by microcapsules containing thermo-responsive poly(N-isopropylacrylamide) (PNIPAAm) gates on their outer pore surfaces for the controlled release of stromal cell-derived factor (SDF)-1α, an important chemokine for stem cell recruitment/homing. Double-phase emulsified condensation polymerization was used to prepare interconnected porous glycidyl methacrylated dextran (Dex-GMA)/gelatin microcapsules, and plasma-graft pore-filling polymerization was used to graft PNIPAAm into the surface pores of the microcapsules. The in vitro results showed that the PNIPAAm-grafted microcapsules featured thermo-responsive drug release properties due to the swollen-shrunken property of PNIPAAm gates in response to temperature changes. After subcutaneous implantation, the thermally responsive microcapsules resulted in a more sustained and long-term SDF-1α release compared with those without PNIPAAm-grafting. In the future, this delivery system may have great potential for use in cell recruiting biomaterials for various tissue engineering and regenerative medicine applications.