Fluorescent nanodiamond bioconjugates on the base of barnase : barstar module

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Specific visualization of tumor cells using upconversion nanophosphors

The development of targeted constructs on the basis of photoluminescent nanoparticles with a high photo- and chemical stability and absorption/emission spectra in the "transparency window" of biological tissues is an important focus area of present-day medical diagnostics. In this work, a targeted two-component construct on the basis of upconversion nanophosphors (UCNPs) and anti-tumor 4D5 scFv was developed for selective labeling of tumor cells overexpressing the HER2 tumor marker characteristic of a number of human malignant tumors. A high affinity barnase: barstar (Bn: Bs) protein pair, which exhibits high stability in a wide range of pH and temperatures, was exploited as a molecular adapter providing self-assembly of the two-component construct. High selectivity for the binding of the two-component 4D5 scFv-Bn: UCNP-Bs construct to human breast adenocarcinoma SK-BR-3 cells overexpressing HER2 was demonstrated. This approach provides an opportunity to produce similar constructs for the visualization of different specific markers in pathogenic tissues, including malignant tumors.6 page(s

Protein-assisted self-assembly of multifunctional nanoparticles

A bioengineering method for self-assembly of multifunctional superstructures with in-advance programmable properties has been proposed. The method employs two unique proteins, barnase and barstar, to rapidly join the structural components together directly in water solutions. The properties of the superstructures can be designed on demand by linking different agents of various sizes and chemical nature, designated for specific goals. As a proof of concept, colloidally stable trifunctional structures have been assembled by binding together magnetic particles, quantum dots, and antibodies using barnase and barstar. The assembly has demonstrated that the bonds between these proteins are strong enough to hold macroscopic (5 nm–3 μm) particles together. Specific interaction of such superstructures with cancer cells resulted in fluorescent labeling of the cells and their responsiveness to magnetic field. The method can be used to join inorganic moieties, organic particles, and single biomolecules for synergistic use in different applications such as biosensors, photonics, and nanomedicine