Photocleavable Hydrogel-Coated Upconverting Nanoparticles: A Multifunctional Theranostic Platform for NIR Imaging and On-Demand Macromolecular Delivery

Abstract

Lanthanide-doped upconverting nanoparticles (UCNPs) have emerged as excellent nanotransducers for converting longer wavelength near-infrared (NIR) light to shorter wavelengths spanning the ultraviolet (UV) to the visible (Vis) regions of the spectrum via a multiphoton absorption process, known as upconversion. Here, we report the development of NIR to UV-Vis-NIR UCNPs consisting of LiYF4:Yb(3+)/Tm(3+)@SiO2 individually coated with a 10 ± 2 nm layer of chitosan (CH) hydrogel cross-linked with a photocleavable cross-linker (PhL). We encapsulated fluorescent-bovine serum albumin (FITC-BSA) inside the gel. Under 980 nm excitation, the upconverted UV emission cleaves the PhL cross-links and instantaneously liberates the FITC-BSA under 2 cm thick tissue. The release is immediately arrested if the excitation source is switched off. The upconverted NIR light allows for the tracking of particles under the tissue. Nucleus pulposus (NP) cells cultured with UCNPs are viable both in the presence and in the absence of laser irradiation. Controlled drug delivery of large biomolecules and deep tissue imaging make this system an excellent theranostic platform for tissue engineering, biomapping, and cellular imaging applications.

Simultaneous Visualization and Quantitation of Multiple Steroid Hormones Based on Signal‐Amplified Biosensing with Duplex Molecular Recognition

“…Most recently, upconversion nanoparticles (UCNPs) have attracted considerable attention as an outstanding class of luminescent nanomaterials for sensing applications . Regarded as a special type of nanophosphor, UCNPs are capable of converting near‐infrared (NIR) light to shorter wavelength luminescence through the energy‐transfer process .…”

Interfacial Assembly of Mesoporous Silica‐Based Optical Heterostructures for Sensing Applications

“…Growing attention has been focused on the development of mesoporous SiO 2 with core–shell structure because of their fascinating properties, such as adaptable compatibility, improved stability, and multifunctionality . In 2008, Zhao and co‐workers described a coating method for preparing magnetic mesoporous SiO 2 microparticles using a SiO 2 ‐coated magnetite template and ordered mesoporous SiO 2 shell with vertically oriented channels using the Stöber method .…”

Spatially and temporally controlled hydrogels for tissue engineering

“…Several approaches that rely on stimulus, such as light [200–202], ultrasound [203–205], temperature [206–208], or electricity [209–211], have been developed to enable physicochemical responses in synthetic hydrogel materials for on-demand controlled molecular release, and some examples are discussed in the following paragraphs.…”