Efficient Encoding of Matrix Microparticles with Nanocrystals for Fluorescent Polyelectrolyte Microcapsules Development

Polyelectrolyte microcapsules development and further use as specific carriers for drug molecules, fluorescent dyes, and metal nanoparticles is a promising approach to designing theranostic agents. Semiconductor nanocrystal quantum dots exhibiting size-dependent optical properties, a high photostability, and optimal fluorescent properties can be advantageous over classical organic fluorophores. The results of elaboration of efficient encoding of matrix microparticles with nanocrystals for development of fluorescent polyelectrolyte microcapsules and the characteristics of the obtained encoded microbeads are demonstrated. Keywords: Semiconductor nanocrystals; encoding of matrix microbeads; theranostic agents, polyelectrolyte microcapsules, layer-by-layer technique

Cytotoxicity of Polyelectrolyte Microcapsules Encoded with Semiconductor Nanocrystals

Polyelectrolyte microcapsules are promising carriers of drugs and diagnostic agents for designing targeted and controlled delivery systems design. The use of quantum dots (QDs) as fluorescent labels in bioimaging is a promising approach to bioimaging tool development. The potential toxicity of QDs makes their applicability as fluorescent labels in vivo questionable. Therefore, the cytotoxicity of polyelectrolyte microcapsules encoded with semiconductor nanocrystals has been investigated. Keywords: Polyelectrolyte microcapsules, semiconductor nanocrystals, cytotoxicity, theranostic agents

Highly Stable, Water-Soluble CdSe/ZnS/CdS/ZnS Quantum Dots with Additional SiO2 shell

Quantum dots (QDs) are fluorescent nanocrystals extensively used today in research and applications. They attract much interest due to the high photostability and fluorescence quantum yields close to 100%. The best QDs are made by synthesis in organic media, and they have to be transferred into aqueous solutions if biomedical applications are concerned. An advanced method for rendering QDs water-soluble is to coat them with hydrophilic SiO2 -layer. However, growing a silica shell with a predetermined thickness is a problem, because uncertain values of the molar extinction coefficients (ε) of core/shell QDs made it impossible to calculate precise yields of the chemical reactions involved. Here we suggest an approach to solving this problem by constructing the structural models of per se and silica-coated QDs followed by measuring ε in a course of the QD synthesis, thus carrying out precise quantitative reactions. Proceeding in such a way, we prepared the CdSe/ZnS/CdS/ZnS QDs with the structure predicted by the model and coated by silica shell. Prepared QDs are characterized by a narrow size distribution and the same fluorescence parameters as the original QDs in the organic medium. Developed approach permitted efficient QDs water-solubilisation and preparation of stable nanoparticles for plethora of biomedical applications.     Keywords: Quantum dots, QD, silica shell, core-shel

Design and characterisation of calcium carbonate microspheres for anticancer drug delivery

International audienceThe development of delivery systems providing prolonged release of antitumor drugs represents one of the challenges in designing and optimization of novel tools for cancer therapy. The employment of spherical inorganic microparticles, in particular, calcium carbonate vaterite microspheres, as microcarriers appears promising because of their porous, matrix structure, biocompatibility, and biodegradability. Here, we summarize the results of the development of the approaches to synthesis of calcium carbonate vaterite microspheres with narrowed size distribution and microencapsulation of low-molecular-weight anticancer drugs, such as doxorubicin hydrochloride into obtained microspheres. Supplementing the reaction mixture with a thickener defines fabrication of homogeneous vaterite microparticles with a spherical shape and an average size of 2 to 3 μm. Synthesised microspheres ensure prolonged release of doxorubicin at physiological pH values and can be used as a delivery system and as a structural component for development of a theranostic platform for tumour treatment and diagnosis

Surface-enhanced Raman scattering of CoV-SARS-2 viral proteins in a strong coupling regime

International audienceFast, sensitive, high-throughput detection of coronavirus antigens at physiologically relevant levels is essential for population screening that could prevent epidemics such as the current COVID-19 global pandemic. Optical methods based on surface-enhanced Raman scattering (SERS) spectroscopy are promising for this purpose because they ensure quick detection of even single biological molecules in a sample. For achieving such a high sensitivity, it is crucial to design SERS-active systems concentrating incident radiation into small sample volumes. Here, metal-dielectric cavities have been obtained through interaction of protein sulfhydryl groups with a SERS-active silver surface. The concentration of light in these cavities allows the differential detection of spike glycoprotein and nucleocapsid protein of SARS-COV-2, which are its key antigens, at physiologically relevant concentrations. The cavity Q-factor can be increased by additionally covering the dielectric protein film with a silver shell to form an ultrathin cavity, which provides an at least tenfold enhancement of the detection signal. The results could be used to design high-throughput systems for specific and sensitive detection of viral antigens and quick diagnosis of viral infections

Cancer cell targeting with functionalized quantum dot-encoded polyelectrolyte microcapsules

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Biofunctionalized Polyelectrolyte Microcapsules Encoded with Fluorescent Semiconductor Nanocrystals for Highly Specific Targeting and Imaging of Cancer Cells

International audienceFluorescent semiconductor nanocrystals or quantum dots (QDs) are characterized by unique optical properties, including a high photostability, wide absorption spectrum, and narrow, symmetric fluorescence spectrum. This makes them attractive fluorescent nanolabels for the optical encoding of microcarriers intended for targeted drug delivery, diagnosis, and imaging of transport processes on the body, cellular, and subcellular levels. Incorporation of QDs into carriers in the form of polyelectrolyte microcapsules through layer-by-layer adsorption of oppositely charged polyelectrolyte polymers yields microcapsules with a bright fluorescence signal and adaptable size, structure, and surface characteristics without using organic solvents. The easily modifiable surface of the microcapsules allows for its subsequent functionalization with capture molecules, such as antibodies, which ensures specific and selective interaction with cells, including tumor cells, with the use of the bioconjugation technique developed here. We obtained stable water-soluble nanolabels based on QDs whose surface was modified with polyethylene glycol (PEG) derivatives and determined their colloidal and optical characteristics. The obtained nanocrystals were used to encode polyelectrolyte microcapsules optically. The microcapsule surface was modified with humanized monoclonal antibodies (Abs) recognizing a cancer marker, epidermal growth factor receptor (EGFR). The possibility of effective, specific, and selective delivery of the microcapsules to tumor cells expressing EGFR has been demonstrated. The results show that the QD-encoded polyelectrolyte microcapsules functionalized with monoclonal Abs against EGFR can be used for targeted imaging and diagnosis