Modularly Assembled Upconversion Nanoparticles for Orthogonally Controlled Cell Imaging and Drug Delivery.

Upconversion nanoparticles (UCNPs) have been used effectively as light transducers to convert near-infrared irradiation to short-wavelength emissions for photoactivation in deep tissues. UCNPs with single/multiple emissions under excitation at a single wavelength can be used for simultaneous activation of single or multiple photosensitive molecules only; an ideal multifunctional UCNP nanoplatform should not only have the ability to load multiple molecules but also should activate them at the right time with the right dose when necessary, depending upon the application for which it is used. The control of many biological processes requires complex (simultaneous or subsequent) photoactivation at different time points.

Upconversion superballs for programmable photoactivation of therapeutics.

Upconversion nanoparticles (UCNPs) are the preferred choice for deep-tissue photoactivation, owing to their unique capability of converting deep tissue-penetrating near-infrared light to UV/visible light for photoactivation. Programmed photoactivation of multiple molecules is critical for controlling many biological processes. However, syntheses of such UCNPs require epitaxial growth of multiple shells on the core nanocrystals and are highly complex/time-consuming.

Manipulating energy migration within single lanthanide activator for switchable upconversion emissions towards bidirectional photoactivation.

Reliance on low tissue penetrating UV or visible light limits clinical applicability of phototherapy, necessitating use of deep tissue penetrating near-infrared (NIR) to visible light transducers like upconversion nanoparticles (UCNPs). While typical UCNPs produce multiple simultaneous emissions for unidirectional control of biological processes, programmable control requires orthogonal non-overlapping light emissions. These can be obtained through doping nanocrystals with multiple activator ions.

Surface protein engineering increases the circulation time of a cell membrane-based nanotherapeutic.

Mammalian cell membranes are often incompatible with chemical modifications typically used to increase circulation half-life. Using cellular nanoghosts as a model, we show that proline-alanine-serine (PAS) peptide sequences expressed on the membrane surface can extend the circulation time of a cell membrane derived nanotherapeutic. Membrane expression of a PAS 40 repeat sequence decreased protein binding and resulted in a 90% decrease in macrophage uptake when compared with non-PASylated controls (P ≤ 0.

Phase angle encoded upconversion luminescent nanocrystals for multiplexing applications.

Lanthanide-doped upconversion nanoparticles (UCNPs) are increasingly used as luminescent candidates in multiplexing applications due to their excellent optical properties. In the past, several encoding identities have been proposed for UCNPs, including emission colour, intensity ratio between different emission bands, colour spatial distribution, and luminescence lifetime. In this paper, a new optical encoding dimension for upconversion nanomaterials is developed by exploring their luminescence kinetics, i.

Quasi-Continuous Wave Near-Infrared Excitation of Upconversion Nanoparticles for Optogenetic Manipulation of C. elegans.

Optogenetics is an emerging powerful tool to investigate workings of the nervous system. However, the use of low tissue penetrating visible light limits its therapeutic potential. Employing deep penetrating near-infrared (NIR) light for optogenetics would be beneficial but it cannot be used directly.

Luminescent lanthanide nanomaterials: an emerging tool for theranostic applications.

Lanthanide materials have been gaining popularity for use in various theranostic applications, primarily due to their unique optical properties such as narrow emission bands, multiple emission wavelengths, emission tunability, long fluorescence lifetime and large Stokes shift. Apart from these, some lanthanide materials also exhibit magnetic and light-up conversion properties. Such nanomaterials have been used for a wide range of applications ranging from detection of biomarkers, in vitro and in vivo imaging to therapeutic applications.

Mesoporous silica-coated upconversion nanocrystals for near infrared light-triggered control of gene expression in zebrafish.

Aim: To develop a platform technology for photoactivation of gene expression in deep tissues.

Materials & Methods: Upconversion nanoparticles (UCNs) were synthesized from rare earth elements like Ytterbium, Yttrium and Thulium. The nanoparticles were then further coated with a layer of mesoporous silica and loaded with photomorpholinos or photocaged plasmids and tested in zebrafish.

Upconversion nanoparticles as versatile light nanotransducers for photoactivation applications.

Remote activation of photoactivable therapeutic compounds by light provides a high spatial and temporal control for activating the therapeutic agent. However, photoactivable compounds are mostly responsive towards ultraviolet (UV) or visible light radiation that has poor tissue penetration depth besides being unsafe to the body in the case of UV light. Nanoparticles with energy upconversion hold potential in overcoming this limit by using safe and deeply penetrating near-infrared (NIR) light.

A paradigm shift in the excitation wavelength of upconversion nanoparticles.

The past two decades witnessed the emergence of upconversion nanoparticles as promising luminophores finding multifarious uses from biological studies to solar cells. Progress in their practical use, however, has been hampered by requirements to be excited within a narrow absorption band at around 980 nm. Since the main constituent of biological tissue--water--absorbs strongly in this region, significant reduction in the penetration depth is anticipated as the 980 nm light gets attenuated travelling through tissues, besides also risking tissue damage from the overheating effect.

Near-infrared-light-based nano-platform boosts endosomal escape and controls gene knockdown in vivo.

Current nanoparticle-based gene delivery techniques face two major limitations, namely, endosomal degradation and poor cytosolic release of the nanoparticles and nonspecificity of treatment. These limitations can be overcome with certain light-based techniques, such as photochemical internalization to enable endosomal escape of the delivered nanoparticles and light-controlled gene expression to overcome the nonspecific effects. However, these techniques require UV/visible light, which is either phototoxic and/or has low tissue penetration capabilities, thus preventing their use in deep tissues in a clinical setting.

Remote activation of biomolecules in deep tissues using near-infrared-to-UV upconversion nanotransducers.

Controlled activation or release of biomolecules is very crucial in various biological applications. Controlling the activity of biomolecules have been attempted by various means and controlling the activity by light has gained popularity in the past decade. The major hurdle in this process is that photoactivable compounds mostly respond to UV radiation and not to visible or near-infrared (NIR) light.