A biomineral-inspired approach of synthesizing colloidal persistent phosphors as a multicolor, intravital light source

Abstract

Many in vivo biological techniques, such as fluorescence imaging, photodynamic therapy, and optogenetics, require light delivery into biological tissues. The limited tissue penetration of visible light discourages the use of external light sources and calls for the development of light sources that can be delivered in vivo. A promising material for internal light delivery is persistent phosphors; however, there is a scarcity of materials with strong persistent luminescence of visible light in a stable colloid to facilitate systemic delivery in vivo. Here, we used a bioinspired demineralization (BID) strategy to synthesize stable colloidal solutions of solid-state phosphors in the range of 470 to 650 nm and diameters down to 20 nm. The exceptional brightness of BID-produced colloids enables their utility as multicolor luminescent tags in vivo with favorable biocompatibility. Because of their stable dispersion in water, BID-produced nanophosphors can be delivered systemically, acting as an intravascular colloidal light source to internally excite genetically encoded fluorescent reporters within the mouse brain.

Nanotransducer-Enabled Deep-Brain Neuromodulation with NIR-II Light

“…In addition, another non-invasive optogenetics approach, sono-optogenetics, is enabled by circulation-delivered nanoscopic light sources (Figure e). ,− Specifically, Wu et al designed and synthesized ZnS-based mechano­luminescent nanoparticles (MLNPs) that can be activated by deep-penetrating focused ultrasound (FUS) . Upon systemic delivery, these MNLPs flow through the entire body, but only emit 470 nm light transiently at the ultrasound focus in the brain.…”

Ultrasound-activated luminescence with color tunability enabled by mechanoluminescent colloids and perovskite quantum dots

“…Synthesis of SMSO colloids SMSO colloids were synthesized according to a previously reported biomineral-inspired suppressed dissolution method. 9,12 The suppressed dissolution method comprises two steps. In the first step, the bulk SMSO material was prepared via a solid-state reaction.…”

“…These ML fluids can thus act as a circulation-delivered intravascular light source and enable unique in vivo applications such as minimally invasive sono-optogenetic neuromodulation and transcranial brain fluorescence imaging. 8–10,12…”

“…These ML fluids can thus act as a circulation-delivered intravascular light source and enable unique in vivo applications such as minimally invasive sono-optogenetic neuromodulation and transcranial brain fluorescence imaging. [8][9][10]12 The capability to excite mechanoluminescence from ML colloids with FUS represents a unique advantage in comparison to that from conventional ML materials. Specifically, FUS is a wireless and non-contact form of energy delivery, 13 owing to its ability to propagate in various mediums and penetrate biological tissue.…”

Ultrasound-Induced Cascade Amplification in a Mechanoluminescent Nanotransducer for Enhanced Sono-Optogenetic Deep Brain Stimulation

“…Utilizing nanoparticles converting ultrasound energy to light has become an increasingly promising technology for combining noninvasive and clinically safe ultrasound technology with an optogenetic toolbox for neuromodulation. − The initial application of sono-optogenetics, which involved rechargeable inorganic mechanoluminescent colloidal solutions for ultrasound-to-light conversion, successfully demonstrated ChR2-expressing neuron activation in the motor cortex of mice but was constrained by increased engineering complexity. − We have recently designed a simpler and more biocompatible liposomal nanolight source triggered by FUS . However, the current sono-mechanoluminescent systems exhibit limited photon yields, which restricts their ability to activate neurons only in shallow brain regions.…”