Search

Frontiers in theranostics are driving the demand for multifunctional nanoagents. Upconversion nanoparticle (UCNP)-based systems activated by near-infrared (NIR) light deeply penetrating biotissue are a powerful tool for the simultaneous diagnosis and therapy of cancer. The intercalation into large polymer micelles of poly(maleic anhydride-alt-1-octadecene) provided the creation of biocompatible UCNPs. The intrinsic properties of UCNPs (core@shell structure NaYF4:Yb3+/Tm3+@NaYF4) embedded in micelles delivered NIR-to-NIR visualization, photothermal therapy, and high drug capacity. Further surface modification of micelles with a thermosensitive polymer (poly-N-vinylcaprolactam) exhibiting a conformation transition provided gradual drug (doxorubicin) release. In addition, the decoration of UCNP micelles with Ag nanoparticles (Ag NPs) synthesized in situ by silver ion reduction enhanced the cytotoxicity of micelles at cell growth temperature. Cell viability assessment on Sk-Br-3, MDA-MB-231, and WI-26 cell lines confirmed this effect. The efficiency of the prepared UCNP complex was evaluated in vivo by Sk-Br-3 xenograft regression in mice for 25 days after peritumoral injection and photoactivation of the lesions with NIR light. The designed polymer micelles hold promise as a photoactivated theranostic agent with quattro-functionalities (NIR absorption, photothermal effect, Ag NP cytotoxicity, and Dox loading) that provides imaging along with chemo- and photothermal therapy enhanced with Ag NPs.

Abstract Upconversion nanoparticles (UCNPs) are a promising nanoplatform for bioreagent formation for in vivo imaging, which emit UV and blue light under the action of near-infrared radiation, providing deep tissue penetration and maintaining a high signal-to-noise ratio. In the case of solid tumor visualization, the UCNP surface functionalization is required to ensure a long circulation time, biocompatibility, and non-toxicity. The effective UCNP accumulation in the solid tumors is determined by the disturbed architecture of the vascular network and lymphatic drainage. This work demonstrates an approach to the UCNP biofunctionalization with endogenous polysialic acid for in vivo bioreagent formation. Bioreagents possess a low level of nonspecific protein adsorption and macrophage uptake, which allow the prolongation of the circulation time in the bloodstream up to 3 h. This leads to an intense photoluminescent signal in the tumor.

In the late 1990s, the unique possibilities application of inorganic nanocrystals with anti-Stokes photoluminescence were demonstrated. In a fairly short period, a significant breakthrough has been achieved in this field due to the development of new and modification of existing methods for the synthesis of these nanomaterials, and the expansion of understanding of the photophysical processes occurring in nanocrystals. The interest from the scientific community is due to the exceptional luminescence properties of upconversion nanomaterials, which can convert photons of the near-infrared spectrum to radiation in the visible and UV ranges. This multiquantum process takes place under low-intensity excitation, which largely determines the use of this class of nanomaterials in high-tech fields, including biotechnology, photochemistry, medicine, solar energy, nanosensorics, etc. The goals of this review are to consider the mechanisms of anti-Stokes luminescence, to analyze the synthesis methods, and to demonstrate the applications of fluoride upconversion nanomaterials, in which they have formed a stable scientific and technological niche.

The lanthanide-doped upconversion nanoparticles (UCNPs) gained great attention as nanoplatforms for optical bioimaging and drug delivery systems. In this work, we developed the multimodal system based on UCNPs modified with thermosensitive polymer and Ag nanoparticles (AgNPs), containing chemotherapeutics, such as doxorubicin and flavin mononucleotide, for visualization and therapy. The drug delivery, cytotoxicity and optical properties were studied.

Photopolymerization of nanocomposite materials using near infrared light is one of the unique technologies based on the luminescent properties of lanthanide-doped upconversion nanoparticles (UCNPs). We explored the UCNP-triggered radical polymerization both in oligomer bulk and on the nanoparticle surface in aqueous dispersion. Core/shell UCNPs NaYF4:Yb3+ and Tm3+/NaYF4 with emitting lines in the ultraviolet and blue regions were used to activate a photoinitiator. The study of the bulk photopolymerization in an initially homogeneous reaction mixture showed the UCNP redistribution due to gradient density occurring in the volume, which led to formation of UCNP superlattices and spheres &ldquo, frozen&rdquo, in a polymer matrix. We also developed a strategy of &ldquo, grafting from&rdquo, the surface, providing polymer shell growth directly on the nanoparticles. The photosensitization of the endogenous water-soluble photoinitiator riboflavin by the resonance energy transfer from UCNPs was demonstrated in the course of monomer glycidyl methacrylate polymerization followed by photocrosslinking with poly(ethylene glycol) diacrylate on the nanoparticle surface.

Lanthanide-based upconversion nanoparticles attach great attention in theranostics due to their unique physicochemical and optical properties. It is innovative platform possessing peculiar properties for luminescent imaging, temperature mapping, sensing, and therapy. In present work we demonstrate advantages of new luminescent agents based on upconversion nanoparticles and hydrophylic biocompatible polymer.

In this work are shown the prospects of using upconversion nanoparticles (UCNPs) as markers for contrast optical imaging of a tumor. For using nanoparticles for biomedical purposes is implemented a technique for coating nanoparticles with polymers, such as PEG and PSA. This approach provides low non-specific adsorption, which prolongs the circulation of UCNPs in mouse bearing Lewis Lung Cancer (LLC) up to 10 hours. These properties allow nanoparticles to quickly accumulate in the tumor. Effective delivery of particles with different polymer coatings in the tumor is demonstrated with the help of an epiluminescent imaging system.