Maria V. Lomova

Layer-by-layer assembled multilayer shells for encapsulation and release of fragrance.

Layer-by-layer assembled shells are prospective candidates for encapsulation, stabilization, storage, and release of fragrances. A shell comprising four alternative layers of a protein and a polyphenol is employed to encapsulate the dispersed phase of a fragrance-containing oil-in-water emulsion. The model fragrance used in this work consists of 10 ingredients, covering a range of typically employed aroma molecules, all premixed in equal mass and with sunflower oil acting as the base. The encapsulated emulsion is stable after 2 months of storage at 4 °C as revealed by static light scattering and confocal laser scanning microscopy. Gas chromatography/mass spectrometry data show that the encapsulation efficiency of 8 out of 10 fragrance ingredients depends on the water solubility: the less water-soluble an ingredient, the more of it is encapsulated. The amount of these fragrance ingredients remaining encapsulated decreases linearly upon emulsion incubation at 40 °C and the multilayer shell does not hinder their release. The other two fragrance ingredients having the lowest saturation vapor pressure demonstrate sustained release over 5 days of incubation at 40 °C. The composition of released fragrance remains almost constant over 3 days of incubation, upon further incubation it becomes enriched with these two ingredients when others start to be depleted.

Multilayer Capsules of Bovine Serum Albumin and Tannic Acid for Controlled Release by Enzymatic Degradation

With the purpose to replace expensive and significantly cytotoxic positively charged polypeptides in biodegradable capsules formed via Layer-by-Layer (LbL) assembly, multilayers of bovine serum albumin (BSA) and tannic acid (TA) are obtained and employed for encapsulation and release of model drugs with different solubility in water: hydrophilic-tetramethylrhodamine-isothiocyanate-labeled BSA (TRITC-BSA) and hydrophobic 3,4,9,10-tetra-(hectoxy-carbonyl)-perylene (THCP). Hydrogen bonding is proposed to be predominant within thus formed BSA/TA films. The TRITC-BSA-loaded capsules comprising 6 bilayers of the protein and polyphenol are benchmarked against the shells composed of dextran sulfate (DS) and poly-l-arginine (PARG) on degradability by two proteolytic enzymes with different cleavage site specificity (i.e., α-chymotrypsin and trypsin) and toxicity for murine RAW264.7 macrophage cells. Capsules of both types possess low cytotoxicity taken at concentrations equal or below 50 capsules per cell, and evident susceptibility to α-chymotrypsin resulted in release of TRITC-BSA. While the BSA/TA-based capsules clearly display resistance to treatment with trypsin, the assemblies of DS/PARG extensively degrade. Successful encapsulation of THCP in the TRITC-BSA/TA/BSA multilayer is confirmed, and the release of the model drug is observed in response to treatment with α-chymotrypsin. The thickness, surface morphology, and enzyme-catalyzed degradation process of the BSA/TA-based films are investigated on a planar multilayer comprising 40 bilayers of the protein and polyphenol deposited on a silicon wafer. The developed BSA/TA-based capsules with a protease-specific degradation mechanism are proposed to find applications in personal care, pharmacology, and the development of drug delivery systems including those intravenous injectable and having site-specific release capability.

Au-nanocluster-loaded human serum albumin nanoparticles with enhanced cellular uptake for fluorescent imaging

Protein-directed fluorescent Au nanoclusters have been widely studied owing to their potential applications in sensing, imaging, and drug and gene delivery. However, the use of nanoclusters in drug delivery is limited by low cellular uptake. In this study, human serum albumin-directed Au nanoclusters served as building blocks to obtain protein nanoparticles by desolvation. The nanoparticles had a decent quantum yield (QY), high colloidal stability and low cytotoxicity, and they could be readily conjugated with biological molecules. The cellular uptake of the Au nanoclusters and nanocluster-loaded protein nanoparticles were studied by confocal fluorescence microscopy. Agglomeration of the protein-directed Au nanoclusters into 50–150-nm nanoparticles dramatically increased the cellular uptake.

Composite magnetic microcapsules based on multilayer assembly of ethanol-soluble polyimide brushes and magnetite nanoparticles: preparation and response to magnetic field gradient

Microcapsules consisting of a calcium carbonate core template surrounded by shells containing magnetite nanoparticles and ethanol-soluble polyimide brushes with polymethacrylic acid side chains were assembled using a layer-by-layer technique under nonaqueous conditions. These microcapsules represent a potential solution to the challenging problem of encapsulating water-soluble compounds, particularly low molecular weight drugs. It was possible to move these microcapsules with magnetite nanoparticles in their shells by applying a magnetic field gradient. The novel microcapsules were characterized by optical microscopy, atomic force microscopy, and scanning electron microscopy. Using the brush-like polyanions instead of linear polyanions made it possible to increase the shell thickness gain per ionic assembly cycle by a factor of ~3.

Transfer Ratio of Langmuir-Blodgett Films as an Indicator of the Single-Crystal Silicon Surface Modified by Polyionic Layers

Multilayer nanoscale Langmuir-Blodgett films based on diphilic β-cyclodextrins with various numbers of alkyl chains were grown on single-crystal silicon substrates both unmodified and modified by cationic and anionic polyelectrolyte layers using the polyion complex technique. Ratios of β-cyclodextrin monolayer transfer on substrates were calculated and analyzed. It was shown that this ratio depends on the sign of the polyelectrolyte adhesive layer charge, as well as on the number of alkyl chains in the β-cyclodextrin molecule and the number of deposited monolayers. The observed phenomena characterizing indicator properties of β-cyclodextrin monolayers were interpreted.

Optical monitoring of adipose tissue destruction under encapsulated lipase action

Enzymatic destruction of adipose tissue has been achieved by encapsulation of lipase into the polymeric microcapsules. Adipose tissue destruction was delayed while lipase is encapsulated comparing with the direct lipase action as demonstrated by optical microscopy and optical coherence tomography in in vitro studies. Raman spectroscopy confirms that triglycerides in fat tissue were cleaved into free fatty acids, glycerol, and possible di- and monoglyceride residues. The results underpin the concept of local and controlled treatment of tissues via encapsulation. Effect of lipase encapsulation into the polymeric microcapsules on adipose tissue destruction compared to free lipase application.

Luminescence monitoring of particle delivery into rat skin in vivo

Delivery of upconversion microparticles [Y2O3:Yb, Er] and quantum dots (CuInS2/ZnS coated with PEG-based amphiphilic polymer) into rat skin using the fractional laser microablation has been studied in vivo. Luminescence spectroscopy, optical coherence tomography, confocal microscopy, and histochemical analysis were used for visualization of nanoparticles in microchannels. Results have shown that the upconversion microparticles are detected more efficiently in comparison with the quantum dots. The fluorescence intensity of the inserted upconversion microparticles is higher, when the Omnipaque™ was applied as a skin optical clearing agent. The fluorescent images of upconversion nanoparticle distribution indicate the advantage of particle delivery into skin by ultrasound.