Assembly and Characterizations of Bifunctional Fluorescent and Magnetic Microneedles With One Decade Length Tunability

Abstract

This report presents the fabrication of bifunctional magnetic and fluorescent microneedles (µNDs) made of a ternary mixture of magnetic nanoparticles (NPs), quantum dots (QDs), and polyelectrolyte. The assembly relies on the electrostatic complexation of negatively charged NPs with positively charged polymer strands and is controlled by the charge ratio between the nanoparticle building blocks and the polymer mortar. The resulting 1D objects can be actuated using an external magnetic field and can be imaged using fluorescence micro scopy, thanks to the fluorescent and superparamagnetic properties inherited from their NP constituents. Using a combination of core and surface characteri zations and a stateoftheart image analysis algorithm, the dependence of the brightness and length on the ternary composition is thoroughly investigated. In particular, statistics on hundreds of µNDs with a range of compositions show that the µNDs have a loglormal length distribution and that their mean length can be robustly tuned in the 5-50 µm range to match the relevant length scales of various applications in micromixing, bioassays or biomechanics.

Rearranging Fluorescence-Magneto Spatiality for “Win-Win” Dual Functions to Enhance Point-of-Care Diagnosis

“…[21] Over the past decades, various synthesis strategies have been proposed for FMNs. [22][23][24][25] For example, a layer-by-layer assembly approach has been applied to synthesize FMNs by electrostatically attracting oppositely charged polyelectrolytes and CdTe quantum dots (QDs) on the surface of Fe 3 O 4 nanoparticles. [26] However, the weak binding affinity resulting from electrostatic interactions often leads to detachment of the exterior fluorescent particles from the FMNs.…”