Ultrasound driven assembly of lignin into microcapsules for storage and delivery of hydrophobic molecules.

Oil-filled microcapsules of kraft lignin were synthesized by first creating an oil in water emulsion followed by a high-intensity, ultrasound-assisted cross-linking of lignin at the water/oil interface. The rationale behind our approach is based on promoting documented lignin hydrophobic interactions within the oil phase, followed by locking the resulting spherical microsystems by covalent cross-linking using a high intensity ultrasound treatment. As further evidence in support of our rationale, confocal and optical microscopies demonstrated the uniformly spherical morphology of the created lignin microparticles. The detailed elucidation of the cross-linking processes was carried out using gel permeation chromatography (GPC) and quantitative (31)P NMR analyses. The ability of lignin microcapsules to incorporate and release Coumarin-6 was evaluated in detail. In vitro studies and confocal laser scanning microscopy analysis were carried out to assess the internalization of capsules into Chinese hamster ovary (CHO) cells. This part of our work demonstrated that the lignin microcapsules are not cytotoxic and readily incorporated in the CHO cells.

Electrochemical investigation of the interaction between lysozyme-shelled microbubbles and vitamin C.

We report loading of vitamin C (ascorbic acid) on to lysozyme-shelled microbubbles. The interaction between lysozyme-shelled microbubbles and vitamin C was studied by use of cyclic and differential pulse voltammetry, zeta potential measurements, and scanning electron microscopy. The effect of microbubbles on electrochemical measurement of ascorbic acid was evaluated. The linear range for ascorbic acid obtained for differential pulse measurement in the presence of 1 mg mL(-1) microbubbles was 1-50 µmol L(-1) (y = 0.067x + 0.130, r(2) = 0.995), with a detection limit of 0.5 µmol L(-1). The experimental conditions, i.e., pH and ionic strength, were optimized to improve the interaction between ascorbic acid and lysozyme-shelled microbubbles. The results were satisfactory when the interaction was performed for 1 h in aqueous solution at pH 6. The amount of vitamin C loaded on the microbubbles (90% of the analyte added, RSD(inter-expt.) = 3%, n = 6) and the stability of microbubbles-ascorbic acid complex (until 72 h at 25 °C) were also evaluated by use of differential pulse voltammetry and zeta potential measurements.

Molecular properties of lysozyme-microbubbles: towards the protein and nucleic acid delivery.

Microbubbles (MBs) have specific acoustic properties that make them useful as contrast agents in ultrasound imaging. The use of the MBs in clinical practice led to the development of more sensitive imaging techniques both in cardiology and radiology. Protein-MBs are typically obtained by dispersing a gas phase in the protein solution and the protein deposited/cross-linked on the gas-liquid interface stabilizes the gas core. Innovative applications of protein-MBs prompt the investigation on the properties of MBs obtained using different proteins that are able to confer them specific properties and functionality. Recently, we have synthesized stable air-filled lysozyme-MBs (LysMBs) using high-intensity ultrasound-induced emulsification of a partly reduced lysozyme in aqueous solutions. The stability of LysMBs suspension allows for post-synthetic modification of MBs surface. In the present work, the protein folded state and the biodegradability property of LysMBs were investigated by limited proteolysis. Moreover, LysMBs were coated and functionalized with a number of biomacromolecules (proteins, polysaccharides, nucleic acids). Remarkably, LysMBs show a high DNA-binding ability and protective effects of the nucleic acids from nucleases and, further, the ability to transform the bacteria cells. These results highlight on the possibility of using LysMBs for delivery of proteins and nucleic acids in prophylactic and therapeutic applications.

Methods of preparation of multifunctional microbubbles and their in vitro / in vivo assessment of stability, functional and structural properties.

Microbubbles (MBs) are ultrasound responsive colloidal particles with a strong potential to become theranostic agents, combining the contrast agent activity with therapeutic functionality. In the last decades, MBs have played a significant role as ultrasound contrast agents in diagnostic imaging. MBs have also shown great potential in applications such as molecular imaging, drug delivery, gene therapy and sonothrombolysis. A full understanding of all physical processes underlying the MBs' stability and acoustic behavior is available in the literature. Efforts have been now addressed to the study of chemical and biological features of multifunctional lipid, protein, or polymer shelled MBs. A number of methods of preparation of "smart" MBs for ultrasound image-guided therapy have been recently developed. In this review, different approaches utilized in preparing multifunctional MBs are discussed with specific attention to the current strategies adopted to design MBs with specialized functions. In vitro / in vivo assessment of MBs' stability and activity will be discussed with a particular emphasis on the emerging applications of MBs for the multiple imaging modalities, the effective opening of blood brain barrier, BBB, and for the therapeutic treatment of antimicrobial films.

Michael-type addition reactions for the in situ formation of poly(vinyl alcohol)-based hydrogels.

Michael-type addition reactions offer the possibility to obtain in situ formation of polymeric hydrogels in the absence of a radical mechanism for the networking process. We explored such a synthetic route for obtaining a poly(vinyl alcohol) (PVA)-based hydrogel as a potential biomaterial for applications in vitro-retinal replacement surgery. The presence of radicals in the reaction medium can represent a risk for in situ surgical treatment. To circumvent this problem we have applied nucleophilic addition to ad hoc modified PVA macromers. The gel formation has been studied with respect to the timing required in this surgery and in terms of the structural characteristics of the obtained network.