Surface Permeability of Membrane and Catalytic Performance Based on Redox-Responsive of Hybrid Hollow Polymeric Microcapsules

“Smart” polymeric microcapsules with excellent permeability of membranes have drawn considerable attention in scientific and industrial research such as drug delivery carriers, microreactors, and artificial organelles. In this work, hybrid hollow polymeric microcapsules (HPs) containing redox-active gold-sulfide bond were prepared with bovine serum albumin, inorganic metal cluster (AuNCs), and poly(N-isopropylacrylamide) conjugates by using Pickering emulsion method. HPs were transferred from water-in-oil to water-in-water by adding PEGbis(N-succinimidylsuccinate). To achieve redox-responsive membrane, the Au-S bond units incorporated into the microcapsules’ membranes, allowed us to explore the effects of a new stimuli, that is, the redox Au-S bond breaking on the microcapsules’ membranes. The permeability of these hybrid hollow polymeric microcapsules could be sensitively tuned via adding environment-friendly hydrogen peroxide (H2O2), resulting from a fast fracture of Au-S bond. Meanwhile, AuNCs and conjugates could depart from the microcapsules, and enhance the permeability of the membrane. Based on the excellent permeability of the membrane, phosphatase was encapsuled into HPs and p-nitrophenyl phosphate as a substrate. After adding 1 × 10−2 and 1 × 10−4 M H2O2, the catalytic efficiency was nearly 4.06 and 2.22 times higher than that of HPs in the absence of H2O2, respectively. Hence, the unique redox-responsive HPs have potential applications in biocatalytic reaction, drug delivery, and materials as well as in bioscience.

Quantification of Residual Perfume by Py-GC-MS in Fragrance Encapsulate Polymeric Materials Intended for Biodegradation Tests

Perfume encapsulates are widely used in commercial products to control the kinetic release of odorant molecules, increase storage stability and/or improve deposition on different substrates. In most of the cases, they consist of core-shell polymeric microcapsules that contain fragrance molecules. A current challenge is to design and produce polymeric materials for encapsulation that are both resistant and non-persistent. The selection of such eco-friendly formulations is linked to a deep understanding of the polymeric material used for encapsulation and its biodegradation profile. To collect this information, pure samples of capsule shells are needed. In this article we present an innovative quantification method for residual volatiles based on pyrolysis-GC-MS to enable validation of sample quality prior to further testing. The presented analytical method also led to the development of a robust and comprehensive purification protocol for polymers from commercial samples. Standard techniques are not suited for this kind of measurement due to the non-covalent embedding of volatiles in the 3D structure of the polymers. We demonstrated the confounding impact of residual volatiles on the estimated biodegradability of fragrance encapsulates.

Non-invasive cell counting of adherent, suspended and encapsulated mammalian cells using optical density

In situ measurement to determine mammalian cell number in a non-invasive, non-destructive and reagent-free manner is needed to enable continuous cell manufacturing. An analytical method is presented for non-invasive cell counting by conducting multiwavelength spectral analysis of mammalian cells achieving a minimal detectable cell count of 62,500 at 295 nm. Light absorbance was insensitive to culture volume, giving an absolute cell count rather than a concentration. The activation state of cells was also considered. The study was extended to quantification within polymeric microcapsules as an advanced substrate for mammalian cell growth in bioreactor formats and resulted in an offset directly correlating with the absorbance maxima of the polymer. These studies provide feasibility for optical density as a simple end point to indirectly quantify mammalian cell number for continuous monitoring of cell cultures.

Preparation and characterization of vetiver oil encapsulated polymeric microcapsules for sedative and hypnotic activity

In the present work, in view of the medicinal properties of vetiver oil (extracted from the roots of Vetiveria zizanioides L.), we made an attempt to encapsulate vetiver oil in a biocompatible polymeric system made of sodium alginate with gellan gum or karaya gum. Sodium alginate and gellan gum or karaya gum were ionotropically cross-linked to encapsulate vetiver oil. Vetiver oil encapsulations in these microcapsules were 35.92 ± 3.18 % to 78.55 ± 3.35%. Vetiver oil encapsulated microcapsules were of spherically shaped with 656-769 µm mean diameter. This vetiver oil encapsulated microcapsules made of alginate-gellan gum blends were found capable of providing a long release of encapsulated oil, showing the potential for the sustained release application. These microcapsules were analyzed by FTIR, DSC, and SEM, etc. In addition, sedative and hypnotic activities of vetiver oil encapsulated polymeric microcapsules in the male Swiss albino mice were evaluated. The sedative-hypnotic activity of vetiver oil encapsulated polymeric microcapsules in rats was observing the number of crossing and motilities. The results proves that vetiver oil encapsulated polymeric microcapsules decreased motility when compared to the control group.

Ortho-substituted azobenzene: shedding light on new benefits

Novel functional polymeric microcapsules, based on modified azobenzene moieties, are exhaustively investigated, both from a theoretical and experimental points of view. Theoretical calculations and several measurements demonstrate that visible light can act as a trigger for release of encapsulated material, as a consequence of trans-cis isomerization which modifies microcapsule surface topography and can induce a “squeezing” release mechanism. Interfacial polymerization of an oil-in-water emulsion is performed and leads to core-shell microcapsules which are characterized by means of atomic force microscopy (AFM), optical microscopy (OM), scanning electron microscopy (SEM) and light scattering. These analyses put into evidence that microcapsules’ size and surface morphology are strongly affected by irradiation under visible light: moreover, these changes can be reverted by sample exposure to temperatures around 50°C. This last evidence is also confirmed by NMR kinetic analyses on modified azobenzene moiety. Finally, it is shown that these smart microcapsules can be successfully used to get a controlled release of actives such as fragrancies, as a consequence of visible light irradiation, as confirmed by an olfactive panel.