Fluorescent Silica Nanoparticles with Well-Separated Intensity Distributions from Batch Reactions

Abstract

Silica chemistry provides pathways to uniquely tunable nanoparticle platforms for biological imaging. It has been a long-standing problem to synthesize fluorescent silica nanoparticles (SNPs) in batch reactions with high and low fluorescence intensity levels for reliable use as an intensity barcode, which would greatly increase the number of molecular species that could be tagged intracellularly and simultaneously observed in conventional fluorescence microscopy. Here, employing an amino-acid catalyzed growth, highly fluorescent SNP probes were synthesized with sizes <40 nm and well-separated intensity distributions, as mapped by single-particle imaging techniques. A seeded growth approach was used to minimize the rate of secondary particle formation. Organic fluorescent dye affinity for the SNP during shell growth was tuned using specifics of the organosilane linker chemistry. This work highlights design considerations in the development of fluorescent probes with well-separated intensity distributions synthesized in batch reactions for single-particle imaging and sensing applications, where heterogeneities across the nanoparticle ensemble are critical factors in probe performance.

Ultrasmall, Bright, and Photostable Fluorescent Core–Shell Aluminosilicate Nanoparticles for Live‐Cell Optical Super‐Resolution Microscopy

“…We immobilized biotinylated Cy5 dye (Cy5-biotin), PEG-Cy5-C' dots, and PEG-Cy5-aC' dots on streptavidin-coated glass dishes as described elsewhere, with Hank's balanced salt solution (HBSS) as the imaging buffer (see Supporting Information). [24,34] HBSS is an aqueous buffer routinely used in live-cell imaging. The immobilized single emitters were imaged under different conditions by a total internal reflection fluorescence (TIRF) microscope.…”

Fluorescent Silica Nanoparticles to Label Metastatic Tumor Cells in Mineralized Bone Microenvironments

“…[25,32] In this study, we synthesized SNPs containing positively charged cyanine dyes (i.e., Cy3(+), Cy5(+)) with a size of 20-30 nm to maximize cellular uptake and retention. [33] Using positively charged rather than negatively charged fluorescent dyes previously published for this size range of particles [28] maximizes the number of dyes fully covalently encapsulated in the silica matrix, [34] leading to optimal fluorescence brightness per dye. Using these SNPs, we first established a reliable labeling protocol for MDA-MB-231 breast cancer cells, then verified that SNP-labeled cells can be detected alongside mineral and autofluorescent bone marrow within a 3D in vitro model of bone metastasis.…”

Controlling Surface Chemical Heterogeneities of Ultrasmall Fluorescent Core–Shell Silica Nanoparticles as Revealed by High-Performance Liquid Chromatography

“…Nanoparticle synthesis is ubiquitous in a host of research fields from energy to healthcare and provides access to a diverse array of materials such as quantum dots or polymer, metal, and oxide nanoparticles. − Key characteristics of successful nanoparticle preparation methods are the batch-to-batch reproducibility and control over properties such as size, brightness, and surface chemistry. − In the last 5–10 years, increasing interest has focused on the synthesis of ultrasmall (diameter <10 nm) nanoparticles. In addition to unique properties emerging at this scale, their small size enables the use of high-performance liquid chromatography (HPLC) to quantitatively analyze particle surface chemical properties. , Although HPLC is ubiquitous in fields with precisely defined molecular materials such as small molecules, macromolecular structures like dendrimers, and proteins, − the successful application of HPLC to inorganic core–organic shell (core–shell) nanoparticles is a recent development. ,, As a result of the well-established versatility of HPLC for synthesis product quality control, this adds a novel and intriguing dimension to the analysis of nanoparticles, e.g., to further tune their surface chemical properties for biological applications .…”