Synthesis, Loading, and Application of Individual Nanocapsules for Probing Single-Cell Signaling

Abstract

This paper describes the synthesis and loading of silica and polystyrene-acrylic based nanocapsules with small molecules. The nanocapsules are used for delivering defined packages of stimuli to single cells with both high spatial and temporal resolutions. To introduce molecules into the capsules, we characterized two approaches. The first approach is based on a base-swell process in which the shell of the capsule is swelled so small molecules can diffuse into the interior of the capsule and be trapped inside once the capsules are de-swelled. The second approach is based on a dry-swell-dry process in which the solution containing the molecules of interest and the nanocapsules is physically dried to promote more molecules to enter into the interior of the capsule. We characterized both methods by monitoring the content of and the release from individual capsules with confocal microscopy and wide-field imaging. To illustrate the biological applications of such nanocapsules, we used optical trapping to position a single carbachol-loaded capsule adjacent to a single CHO cell that has been transfected with muscarinic acetylcholine (M1) receptors, released the carbachol from the capsule with a single 3-ns N2 laser pulse, and then monitored the subsequent intracellular signaling triggered by the binding of carbachol to the M1 receptors.

Mesoporous Silica Nanoparticles for Drug Delivery and Biosensing Applications

“…[40] In contrast to these silica-based core/shell nanoassemblies, the utilization of silica particles with different porous structures as carriers for drug delivery has been exploited. For example, hollow silica micro- [41] and nanocapsules [42,43] containing magnetic nanoparticles inside have proven to be able to absorb drugs that can later be released. Also, silica nano-"test tubes" that can be loaded with drugs and capped with nanoparticles have been reported recently.…”

Light at work: The use of optical forces for particle manipulation, sorting, and analysis

“…Sun and Chiu used optically manipulated synthetic nanocapsules loaded with cellular effector to induce signaling cascade in Chinese hamster ovary cells expressing membrane receptors for the used effector; the effector molecules were released from the capsules using a single UV laser pulse [462].…”

Neuron Cells Uptake of Polymeric Microcapsules and Subsequent Intracellular Release

“…Therefore, it is desirable to load bio-molecules of interest with minimal interference to cell activity and to release [3] these bio-molecules with high precision in terms of quantity, temporal and spatial location. [4] Doing that non-destructively, i.e. without affecting metabolism of living cells, and without damage to the cell membrane would open extensive opportunities in terms of studying important intracellular processes and neuron network signaling.…”