Introduction

Fluorescent particles are prepared by incorporating selected fluorophores into monodisperse polystyrene particles through swelling process or copolymerizing styrene with various organic fluorescent dyes, which produce fluorophores labeled polystyrene particles with satisfactory properties. Functional groups or biological macromolecules (carboxyl, amino, streptavidin, biotin, etc.) can be quantitatively modified on the surface of microsphere as linking groups for immunoanalysis, making fluorescent polystyrene microspheres have a wide range of applications, including lateral chromatography, cell imaging, microfluidics and fluorescence enzyme-related immunosorbent assay.      Fluorescent particles with single or multiple fluorophores are available in various sizes, emission spectra and combinations. Many are suitable for uses in flow cytometry, fluorescence microscopy, phagocytosis studies, and cell labeling[1-5].

Abvigen Inc. offers a wide range of Fluorescent Polystyrene Particles, including Green PS Fluorescent Particles, Blue PS Fluorescent Particles, Red PS Fluorescent Particles and Orange PS Fluorescent Particles. The product size is adjustable within the range of nanometers to micrometers, and can be further flexibly adjusted according to customer requirements and use conditions to achieve customized supply.

Preparation Method

Miniemulsion polymerization[6]: 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.

THF/water swelling procedure[7]: Aiming at the derivation of a generalized procedure for the straightforward preparation of particles fluorescing in the visible and near-infrared (NIR) spectral region, different swelling procedures for the loading of the hydrophobic polarity-probe Nile Red into nano- and micrometer sized polystyrene particles were studied and compared with respect to the optical properties of the resulting particles. The effect of the amount of incorporated dye on the spectroscopic properties of the particles was investigated for differently sized beads with different surface chemistries, i.e., non-functionalized, amino-modified and PEG-grafted surfaces.             Moreover, photostability and leaking studies were performed. The main criterion for the optimization of the dye loading procedures was a high and thermally and photochemically stable fluorescence output of the particles for the future application of these systems as fluorescent labels.

Half seeded emulsion polymerization method[8]: The half seeded emulsion polymerization method was employed to encapsulate fluorescent dye, bromocresol purple (BCP) in polystyrene nanoparticles (PSN) to produce dye/polymer composite colorants.  

Combined swelling-diffusion technique[9]: A series of water-insoluble, biologically compatible dyes, meso-tetraphenylchlorin, meso tetraphenylporphyrin and chlorophyll-a, were successfully incorporated into beads composed of linear polystyrene (PS) via a tunable combined swelling-diffusion process. Dyed PS beads were prepared by the addition of a dye solution in tetrahydrofuran to an aqueous suspension of 10 lm PS beads in the presence of a poly((ethylene glycol)-b-(propylene glycol)-b-(ethylene glycol)) block copolymer surfactant. The presence of surfactant was found to be beneficial to prevent particle aggregation, especially at tetrahydrofuran contents above 30%. Dye loading was shown to be tunable by simple adjustments in dye composition.

Self-assembly of copolymers containing AIE moieties[10]: A cross-linkable aggregation induced emission (AIE) dye (named as R-E) with two vinyl end groups was facilely incorporated into polymer nanoparticles through reversible addition–fragmentation chain transfer polymerization. Thus obtained polymeric nanoparticles showed uniform size, high water dispersibility, strong red fluorescence and excellent biocompatibility, making them promising for cell imaging applications.

Co-nanoprecipitation[11]: Aggregation-induced emission (AIE)-active polymer prodrug nanoparticles were readily prepared by growing short, well-defined polymer chains from an AIE dye by nitroxide-mediated polymerization, followed by co-nanoprecipitation of the resulting conjugates with similarly constructed anticancer polymer prodrugs. The nanoparticles had sharp fluorescence signal offering excellent imaging ability in living cells and their intra cellular localization to be accurately monitored.

Emulsion polymerization[12]: A polymerizable AIE dye (named as PhE) with double bond end functional group as one of components was facilely incorporated into hydrophobic core of polymer nanoparticles. Thus obtained polymer nanoparticles (named as PhE-Pst NPs) emitted strong fluorescence and high water dispersibility owing to partial aggregation of PhE and surface covered with hydrophilic shell. More important, these FONs showed spherical morphology, uniform size (about 200 nm) and excellent biocompatibility, making them promising for bioimaging applications.

Application

Cell labeling[6];

Drug carrier[7];

Imaging[10];

Phagocytosis studies[13];

Calibration of flow cytometry;

Lateral chromatography;

Microfluidics;

Fluorescence enzyme-related immunosorbent assay;

Fluorescence microscopy

Advantages

Monodisperse Particles;

High particle size uniformity;

High-intensity fluorescence;

Available with red, green orange and blue fluorescence;

Designed with carboxylic acid groups (COOH) and amino groups (NH2) on the particle surface for the covalent binding of proteins, antibodies or other molecules;

Offered with streptavidin on the surface for binding of biotinylated molecules;

Outstanding long-term stability under proper storage conditions (both color and fluorescence);

Spherical shape;

Great resistance to photobleaching;

Minimized dye leaching