Preparation of Fluorescent Carboxyl and Amino Functionalized Polystyrene Particles by Miniemulsion Polymerization as Markers for Cells

Abstract

Summary: A series of fluorescent polystyrene latex particles with carboxyl and amino functionalities on their surface were synthesized by the miniemulsion technique. The fluorescent dye N‐(2,6‐diisopropylphenyl)perylene‐3,4‐dicarboximide (PMI) was incorporated into the copolymer nanoparticles formulated from styrene and acrylic acid or styrene and aminoethyl methacrylate hydrochloride. The resulting latexes were stable and showed a monodisperse size distribution. The particle size depended on the amount and nature of the functional comonomer and was in the range 100–175 nm. All latexes were characterized by transmission electron microscopy (TEM), dynamic light scattering, UV‐Vis spectroscopy and zeta potential measurements. The amount of surface functional groups was determined by electrolyte titration. Furthermore, the functionalized fluorescent particles were utilized as markers for HeLa cells and cell uptake was visualized using fluorescence microscopy. The correlation of the uptake of nanoparticles with the surface charge was determined by FACS measurements.Confocal fluorescent microscopy of HeLa cells after the uptake of amino functionalized particles (green).magnified imageConfocal fluorescent microscopy of HeLa cells after the uptake of amino functionalized particles (green).

Expanding the dynamic measurement range for polymeric nanoparticle pH sensors

“…8 However, when preparing the nanosensors by reverse microemulsion polymerization using hexane and water, in the presence of dioctyl sodium sulfosuccinate (AOT) and with Brij30 as a co-surfactant, we found that even after 5 days of dialysis, the nanoparticles still had a negative z-potential (BÀ15 mV), which was due to AOT adhesion to the surface of the NPs. 10 The negative surface charge results in poor cellular uptake of the nanoparticles and the AOT The nanoparticles with free amines (NP-NH 2 ) were prepared by copolymerization of acrylamide and bismethylacrylamide with 3-amino-propyl-acrylamide in a microemulsion (for experimental details see ESIw).…”

From polymeric particles to multifunctional nanocapsules for biomedical applications using the miniemulsion process

“…1). 17,18 A copolymerization with functional monomer(s) allows the functionalization of the nanoparticles' surface with different groups in a controlled manner (see also below).…”

“…By the variation of functional groups and their density on the particle surface, it was clearly demonstrated that the surface groups significantly impart the rate of cellular uptake. 18,38,100 The functionalization of well-defined PU nanocapsules with an aqueous core prepared by performing a polyaddition at the interface of inverse miniemulsion droplets could be demonstrated. 101 The miniemulsion technique involving the nanoreactor concept allows one to obtain an encapsulation efficiency as high as 90% within the nanocapsules.…”

“…115 Both techniques were based on the reliable and uniform distribution of the fluorescent dye inside the nanoparticles. 18,100 Here, the hydrophobic dye N-(2,6-diisopropylphenyl)perylene-3,4-dicarbonacidimide was used. It could be shown that especially the highly amino-functionalized nanoparticles are favorably internalized in all the investigated cell lines.…”

“…Each latex was tested in triplicate. 18 To investigate the uptake path in HeLa cells, positively and negatively charged PS nanoparticles of the same size were applied in combination with selective inhibitors for different uptake mechanisms. 83 Here, the different uptake mechanisms known so far (e.g., clathrin or caveolin mediated endocytosis, see Fig.…”