Harmonic Nanocrystals for Biolabeling: A Survey of Optical Properties and Biocompatibility

Abstract

Nonlinear optical nanocrystals have been recently introduced as a promising alternative to fluorescent probes for multiphoton microscopy. We present for the first time a complete survey of the properties of five nanomaterials (KNbO(3), LiNbO(3), BaTiO(3), KTP, and ZnO), describing their preparation and stabilization and providing quantitative estimations of their nonlinear optical response. In the light of their prospective use as biological and clinical markers, we assess their biocompatibility on human healthy and cancerous cell lines. Finally, we demonstrate the great potential for cell imaging of these inherently nonlinear probes in terms of optical contrast, wavelength flexibility, and signal photostability.

Total Synthesis and Biological Evaluation of Jerantinine E

“…A first moderately invasive cell line (MCF-7) was selected from breast ductal carcinoma in conjunction with a second highly invasive breast cancer cell line (MDA-MB-231). [11] The human adenocarcinoma cell line (A549) derived from alveolar epithelial cells and adenosquamous carcinoma cell line (HTB-178) [12] were chosen to serve as lung cancer model cell lines. The two enantiomers of jerantinine E (5) were first separated by chiral chromatography and their cytotoxic activity examined separately.…”

“…[18] A human adenocarcinoma cell line (A549) derived from alveolar epithelial cells and an adenosquamous carcinoma cell line (HTB-178) were selected as lung cancer models. [19] Cells were grown for 24 hours in 48 well plates (250 µL/well), after which the medium was exchanged with jerantinine E (5) containing medium at the indicated concentrations (prepared from stock solutions of either 1900 mg/L or 770 g/mL jerantinine E (5)), followed by an incubation for 24 or 72 hours. At the end of corresponding incubation periods, cell viability was evaluated using the MTT assay.…”

Accumulating advantages, reducing limitations: Multimodal nonlinear imaging in biomedical sciences – The synergy of multiple contrast mechanisms

“…While luminescence is based on absorption and may result in bleaching, SHG labels do not absorb and provide further advantageous properties like e.g. no photobleaching or blinking, excitation wavelength tunability, spectrally narrow and coherent emission as well as orientation sensitivity [72,73]. SHG active potassium niobate nanoparticles have been used to investigate the evolution of embryonic stem cells [72].…”

“…Also ZnO nanoparticles are non toxic, produce extraordinary bright SHG signals, which are not affected by photobleaching and can be used for highly localized heating by two photon absorption [74]. A comprehensive study on such optical nanocrystals assessed also the biocompatibility and photostability [73]. Among specific probes for THG are carotenoids, which are also ideally biocompatible [75].…”

Resonant plasmonic nanoparticles for multicolor second harmonic imaging

“…[1][2][3][4] To overcome these limitations, researchers have recently devoted considerable attention to a different kind of marker: nanoparticles (NP) that can be excited via two-photon excitation and generate second harmonic (SH) radiation. 2,3,5,6 NPs like barium titanate (BaTiO 3 ), lithium niobate (LiNbO 3 ), iron iodate (Fe(IO 3 ) 3 ), silicon carbide (SiC), and zinc oxide (ZnO) 2,5 are stable over blinking and bleaching, which allows long time observations, emit in a relatively narrow spectral range, so they can be spectrally separated from sample autofluorescence, and can be excited with near infrared light, which limits photo-damage of the sample and increases the penetration depth for deep tissue imaging. 7 However, the emission spectrum of these NPs is mainly determined by the excitation laser and does not change for different NPs.…”