Live Cell Poration by Au Nanostars to Probe Intracellular Molecular Composition with SERS.

A new type of flat substrate has been used to visualize structures inside living cells by surface-enhanced Raman scattering (SERS) and to study biochemical processes within cells. The SERS substrate is formed by stabilized aggregates of gold nanostars on a glass microscope slide coated with a layer of poly (4-vinyl pyridine) polymer. This type of SERS substrate provides good cell adhesion and viability. Au nanostars' long tips can penetrate the cell membrane, allowing it to receive the SERS signal from biomolecules inside a living cell. The proposed nanostructured surfaces were tested to study, label-free, the distribution of various biomolecules in cell compartments.

Transdermal platform for the delivery of the antifungal drug naftifine hydrochloride based on porous vaterite particles.

Development of a skin-targeted particulate delivery system providing an extended or sustained release of the payload and a localized therapeutic effect is one of the main challenges in the treatment of fungal skin infections. In the topical administration of antifungals, the drug should penetrate into the stratum corneum and lower layers of the skin in effective concentrations. Here, we introduce biodegradable calcium carbonate carriers containing 4.9% (w/w) of naftifine hydrochloride antimycotic allowing the efficient accumulation into the skin appendages. The proposed particulate formulation ensures the enhancement of the local drug concentration, prolongation of the payload release, and control over its rate. Furthermore, it provides a highly efficient cellular uptake and excellent bioavailability in vitro and enables a deep penetration during transfollicular delivery in vivo. The enhanced fungi growth inhibition efficiency of naftifine-loaded calcium carbonate carriers compared to naftifine solution makes them a promising alternative to creams and gels currently existing on the market.

Enhancement of Biomimetic Enzymatic Mineralization of Gellan Gum Polysaccharide Hydrogels by Plant-Derived Gallotannins.

Mineralization of hydrogel biomaterials with calcium phosphate (CaP) is considered advantageous for bone regeneration. Mineralization can be both induced by the enzyme alkaline phosphatase (ALP) and promoted by calcium-binding biomolecules, such as plant-derived polyphenols. In this study, ALP-loaded gellan gum (GG) hydrogels were enriched with gallotannins, a subclass of polyphenols. Five preparations were compared, namely three tannic acids of differing molecular weight (MW), pentagalloyl glucose (PGG), and a gallotannin-rich extract from mango kernel (Mangifera indica L.). Certain gallotannin preparations promoted mineralization to a greater degree than others. The various gallotannin preparations bound differently to ALP and influenced the size of aggregates of ALP, which may be related to ability to promote mineralization. Human osteoblast-like Saos-2 cells grew in eluate from mineralized hydrogels. Gallotannin incorporation impeded cell growth on hydrogels and did not impart antibacterial activity. In conclusion, gallotannin incorporation aided mineralization but reduced cytocompatibility.

Freezing-Induced Loading of TiO2 into Porous Vaterite Microparticles: Preparation of CaCO3/TiO2 Composites as Templates To Assemble UV-Responsive Microcapsules for Wastewater Treatment.

The photocatalytic degradation of organic molecules is one of the effective ways for water purification. At this point, photocatalytic microreactor systems seem to be promising to enhance the versatility of the photoassisted degradation approach. Herein, we propose photoresponsive microcapsules prepared via layer-by-layer assembly of polyelectrolytes on the novel CaCO3/TiO2 composite template cores. The preparation of CaCO3/TiO2 composite particles is challenging because of the poor compatibility of TiO2 and CaCO3 in an aqueous medium. To prepare stable CaCO3/TiO2 composites, TiO2 nanoparticles were loaded into mesoporous CaCO3 microparticles with a freezing-induced loading technique. The inclusion of TiO2 nanoparticles into CaCO3 templates was evaluated with scanning electron microscopy and elemental analysis with respect to their type, concentration, and number of loading iterations. Upon polyelectrolyte shell assembly, the CaCO3 matrix was dissolved, resulting in microreactor capsules loaded with TiO2 nanoparticles. The photoresponsive properties of the resulted capsules were tested by photoinduced degradation of the low-molecule dye rhodamine B in aqueous solution and fluorescently labeled polymer molecules absorbed on the capsule surface under UV light. The exposure of the capsules to UV light resulted in a pronounced degradation of rhodamine B in capsule microvolume and fluorescent molecules on the capsule surface. Finally, the versatility of preparation of multifunctional photocatalytic and magnetically responsive capsules was demonstrated by iterative freezing-induced loading of TiO2 and magnetite Fe3O4 nanoparticles into CaCO3 templates.

Biodegradable Nanocarriers Resembling Extracellular Vesicles Deliver Genetic Material with the Highest Efficiency to Various Cell Types.

Efficient delivery of genetic material to primary cells remains challenging. Here, efficient transfer of genetic material is presented using synthetic biodegradable nanocarriers, resembling extracellular vesicles in their biomechanical properties. This is based on two main technological achievements: generation of soft biodegradable polyelectrolyte capsules in nanosize and efficient application of the nanocapsules for co-transfer of different RNAs to tumor cell lines and primary cells, including hematopoietic progenitor cells and primary T cells. Near to 100% efficiency is reached using only 2.5 × 10-4 pmol of siRNA, and 1 × 10-3 nmol of mRNA per cell, which is several magnitude orders below the amounts reported for any of methods published so far. The data show that biodegradable nanocapsules represent a universal and highly efficient biomimetic platform for the transfer of genetic material with the utmost potential to revolutionize gene transfer technology in vitro and in vivo.

Alkaline Phosphatase Delivery System Based on Calcium Carbonate Carriers for Acceleration of Ossification.

Composite bioceramic and hydrogel-based containers harboring alkaline phosphatase are generated through encapsulation of this enzyme by its immobilization into CaCO3-based bioceramic materials in combination with a hydrogel assembly technique and subsequent gelification. A refined way of synthesis and modification allows preparing the enzyme delivery system with functionalized protection layers. The particles are characterized by electron microscopy, Fourier transform infrared (FTIR) spectroscopy, and enzyme activity measurements. Loading efficiency and loading capacity are investigated depending on particle size, time of enzyme loading, and various container compositions and enzyme concentrations. Our results reveal that the size of particles influences their morphology and this, in turn, affects the activity of the encapsulated enzymes. Various functionalizations of the surfaces, including protection by the hydrogel layer, formation of hollow silver alginate, or calcium alginate encapsulation, decrease the enzymatic activity. The presence of a good therapeutic effect on osteoblastic cells coupled with a relatively high loading capacity, biocompatibility, and ease of fabrication suggests that the developed carriers are promising candidates for efficient drug delivery, especially in the field of bone reconstruction.

Physical properties and cytotoxicity of silver nanoparticles under different polymeric stabilizers.

At present day, silver nanoparticles are widely used in different fields of human activity. Due to the unique combination of physical and chemical properties, silver nanoparticles have high reactivity and antibacterial activity against microorganisms. For the same reason, silver nanoparticles can render a cytotoxic effect on eukaryotic cells. The usage of different polymeric compounds as stabilizers can allow reducing of it and saving antibacterial activity. With this regard, the examination of new nanoparticles' stabilizers is a vital task. In addition, for the safe usage of silver nanoparticles it is necessary to estimate some of their physical properties and cytotoxicity. Here we evaluated the shape, size, UV-visible absorption, fluorescence, z-potential and cytotoxicity of single silver nanoparticles and nanoparticles, stabilized by polyvinyl alcohol, sodium carboxymethylcellulose, sodium dodecyl sulfate, sodium oleate and agarose. We found that nanoparticles stabilized by all investigated polymeric compounds with the exception of sodium dodecyl sulfate and sodium oleate did not possess significant cytotoxic effect on the test cell culture.

Novel type of hollow hydrogel microspheres with magnetite and silver nanoparticles.

A novel type of microcontainers based on hollow silver alginate microspheres and magnetite nanoparticles is reported as development of recently published technology. Magnetite nanoparticles were incorporated by two methods - co-precipitation with porous calcium carbonate during template formation and adsorption onto CaCO3 particles or microcontainers' shell. Amount of magnetite loaded and microshells size (4.6 to 6.9 µm) were found to depend on the chosen method for magnetite nanoparticles incorporation. Stability of hollow microshells in saline, phosphate buffer and culturing media was studied. Microcontainers' susceptibility to magnetic field was investigated in solutions of varied viscosity, and their group movement velocity under constant magnetic field was evaluated by sequential optical microscopy imaging. Cell viability tests with prepared microshells were performed that demonstrated negligible cytotoxicity effect on human dermal fibroblasts cells. With HeLa cells moderate viability inhibition was found at high carriers:cells ratio at early time points which is attributed to more active and receptor-mediated endocytosis of carriers as well as known cytotoxicity of magnetite in some cancer cells. At 24 and 48 h time points HeLa cells proliferation fully recovers. Reported data opens perspectives for further biomedical-oriented studies and application of this novel kind of microcontainers with a number of techniques applicable for imaging, control and triggered cargo release provided by presence of silver and magnetite nanoparticles in the carriers and their suitability for further versatile functionalization by traditional LbL approach if needed.

High-efficiency freezing-induced loading of inorganic nanoparticles and proteins into micron- and submicron-sized porous particles.

We demonstrate a novel approach to the controlled loading of inorganic nanoparticles and proteins into submicron- and micron-sized porous particles. The approach is based on freezing/thawing cycles, which lead to high loading densities. The process was tested for the inclusion of Au, magnetite nanoparticles, and bovine serum albumin in biocompatible vaterite carriers of micron and submicron sizes. The amounts of loaded nanoparticles or substances were adjusted by the number of freezing/thawing cycles. Our method afforded at least a three times higher loading of magnetite nanoparticles and a four times higher loading of protein for micron vaterite particles, in comparison with conventional methods such as adsorption and coprecipitation. The capsules loaded with magnetite nanoparticles by the freezing-induced loading method moved faster in a magnetic field gradient than did the capsules loaded by adsorption or coprecipitation. Our approach allows the preparation of multicomponent nanocomposite materials with designed properties such as remote control (e.g. via the application of an electromagnetic or acoustic field) and cargo unloading. Such materials could be used as multimodal contrast agents, drug delivery systems, and sensors.

Carbon dot aggregates as an alternative to gold nanoparticles for the laser-induced opening of microchamber arrays.

Carbon dots (CDs) are usually used as an alternative to other fluorescent nanoparticles. Apart from fluorescence, CDs also have other important properties for use in composite materials, first of all their ability to absorb light energy and convert it into heat. In our work, for the first time, CDs have been proposed as an alternative to gold nanostructures for harvesting light energy, which results in the opening of polymer-based containers with biologically active compounds. In this paper, we propose a method for the synthesis of polylactic acid microchamber arrays with embedded CDs. A comparative analysis was made of the damage to microchambers functionalized with gold nanorods and with CD aggregates, depending on the wavelength and power of the laser used. The release of fluorescent cargo from the microchamber arrays with CD aggregates under laser exposure was demonstrated.

Microstructured Waveguides with Polyelectrolyte-Stabilized Gold Nanostars for SERS Sensing of Dissolved Analytes.

A sensor based on microstructured waveguides (MWGs) with a hollow core inner surface covered with polyelectrolyte-layer-stabilized gold nanostars was developed for the SERS sensing of dissolved analytes. A polyelectrolyte-layer coating over the inner surface of glass cladding served as a spacer, reducing nonlinear optical effects in the glass near plasmonic hotspots of nanoparticles, as a stabilizing agent for thermodynamically unstable gold nanostars and as an optical coating for the fine-tuning of MWG bandgaps. This approach can be used to construct different kinds of SERS sensors for dissolved analytes, providing conservation, the prevention of coagulation, and the drying of a liquid sample for the time required to record the signal.

Silver Alginate Hydrogel Micro- and Nanocontainers for Theranostics: Synthesis, Encapsulation, Remote Release, and Detection.

We have designed multifunctional silver alginate hydrogel microcontainers referred to as loaded microcapsules with different sizes by assembling them via a template assisted approach using natural, highly porous calcium carbonate cores. Sodium alginate was immobilized into the pores of calcium carbonate particles of different sizes followed by cross-linking via addition of silver ions, which had a dual purpose: on one hand, the were used as a cross-linking agent, albeit in the monovalent form, while on the other hand they have led to formation of silver nanoparticles. Monovalent silver ions, an unusual cross-linking agent, improve the sensitivity to ultrasound, lead to homogeneous distribution of silver nanoparticles. Silver nanoparticles appeared on the shell of the alginate microcapsules in the twin-structure as determined by transmission electron microscopy. Remote release of a payload from alginate containers by ultrasound was found to strongly depend on the particle size. The possibility to use such particles as a platform for label-free molecule detection based on the surface enhanced Raman scattering was demonstrated. Cytotoxicity and cell uptake studies conducted in this work have revealed that microcontainers exhibit nonessential level of toxicity with an efficient uptake of cells. The above-described functionalities constitute building blocks of a theranostic system, where detection and remote release can be achieved with the same carrier.

Anticancer drug delivery system based on calcium carbonate particles loaded with a photosensitizer.

In photodynamic therapy (PDT), photosensitizers are required to arrive in high concentrations at selective targets like cancer cells avoiding toxicity in healthy tissue. In this work, we propose the application of porous calcium carbonate carriers in the form of polycrystalline vaterite for this task. We investigated the loading efficiency for the photosensitizer Photosens in vaterite micro- and nanocarriers. A possible release mechanism depending on the surrounding pH was studied, showing a fast degradation of the carriers in buffers below pH7. These results hold out the prospect of a novel PDT drug delivery system. Variation of particle size or additional coatings allow custom-design of workload release curves. An intrinsic cancer-sensitivity can be expected from the pH-dependent release in the acidic microenvironment of cancer tissue.