Paper
9 December 2016 Onion-like surface design of upconverting nanophosphors modified with polyethylenimine: shielding toxicity versus keeping brightness?
Anna Guller, Annemarie Nadort, Alla Generalova, Inna Kornienko, Elena Petersen, Yi Qian, Anatoly Shekhter, Ewa Goldys, Andrei Zvyagin
Author Affiliations +
Proceedings Volume 10013, SPIE BioPhotonics Australasia; 100132Q (2016) https://doi.org/10.1117/12.2244636
Event: SPIE BioPhotonics Australasia, 2016, Adelaide, Australia
Abstract
Background: Upconverting nanoparticles (UCNPs) represent a unique class of nanomaterials, able to convert infrared excitation light into long lifetime visible and infrared photoluminescence, within the “optical transparency window” of biological tissues. This makes UCNPs an attractive contrast agent for background-free bioimaging. However, assynthesized UCNPs are hydrophobic and need additional surface coating for stability in water-based solutions and further functionalization. Polyethylenimine (PEI), a polycationic amphiphilic polymer, is a well-known transfection agent for gene delivery and a popular material for UCNPs surface hydrophilization. Combining the functional properties of UCNPs and PEI is extremely useful for precise visualization of genetic manipulations and intracellular drug delivery. At the same time, PEI is toxic to cells, while the photoluminescent properties of UCNPs are very sensitive to surface chemistry and environment. Then, creation of hydrophilic, biocompatible and simultaneously bright UCNPs, modified by PEI (UCNP-PEI), is a challenging task.

Objectives: To analyze the effects of multilayer shielding coatings on cytotoxicity, cellular uptake and photoluminescent properties of UCNP-PEI.

Methods and results: UCNP-PEI were modified with additional two or three layers of various polymers and characterized by size, surface charge and photophysical properties. HaCaT keratinocytes were exposed to the particles for 24 or 120 h to study the cytotoxicity and cellular uptake. The results show that onion-like coatings of UCNP-PEI simultaneously decrease cytotoxicity and relative luminescence of the particles, depending on structure and method of formation of multilayer coating.

Conclusions: Rational design of UCNP-PEI using extra coatings layers can help to keep acceptable levels of biocompatibility and photoluminescence intensity.
© (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Anna Guller, Annemarie Nadort, Alla Generalova, Inna Kornienko, Elena Petersen, Yi Qian, Anatoly Shekhter, Ewa Goldys, and Andrei Zvyagin "Onion-like surface design of upconverting nanophosphors modified with polyethylenimine: shielding toxicity versus keeping brightness?", Proc. SPIE 10013, SPIE BioPhotonics Australasia, 100132Q (9 December 2016); https://doi.org/10.1117/12.2244636
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KEYWORDS
Coating

Particles

Luminescence

Upconversion

Polymers

Multilayers

Nanoparticles

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