Colloidal templating: seeded emulsion polymerization of a soluble shell with a controlled alkyne surface density

Abstract

A general methodology for producing ca. 100 nm core-shell colloidal particles in which the shell has an elevated alkyne functionality and yet remains thermoplastic is presented. The availability of accessible alkyne groups on the surface of the aqueous-phase particles allows for the in situ surface modification of the particles through a copper(I) catalyzed Huisgen 1,3-dipolar cycloaddition with an azide-terminated surface agent. The core is an extensively crosslinked polymer which can be easily removed by dispersing the particles in a solvent and centrifuging and collecting the cores, leaving the solubilized shells. This allows for the complete characterization of the colloidal surface reactions in the absence of the volumetrically dominant core. The technique is demonstrated with a core-shell colloid composed of a 135 nm crosslinked polystyrene (PS) core coated with a ca. 10 nm thick uncrosslinked poly(methyl acrylate-co-propargyl acrylate) shell. Due to the applicability of this technique for generating particles useful in biomedical imaging or drug delivery applications, the core-shell particles are surface modified with a variety of azide-terminated poly(ethylene glycol) (PEG) derivatives, including a poloxamer which was terminated on either end by an azide and a naphthalimide chromophore. The resulting fluorescent particles had an absorbance at 413 nm and peak emission at 525 nm. The PEG derivatives could be attached to the particles at a grafting density of ca. 0.2-0.3 groups/nm 2 .

Sequential Photochemistry of Dibenzo[a,e]dicyclopropa[c,g][8]annulene-1,6-dione: Selective Formation of Didehydrodibenzo[a,e][8]annulenes with Ultrafast SPAAC Reactivity

“…The applicability of this platform for the cross-linking of larger substrates was demonstrated on the example of BSA-N 3 and PEG 5000 -azide 23 cross-linking (Scheme 8). First, PEG-azide was incubated with an equimolar amount of MC-DIBOD 5a for 12 hours at room temperature.…”

“…The preparation of mixed triazoles ( 7 and 8 , Scheme ) and cross-conjugation of BSA–N 3 with rhodamine B azide demonstrated the utility of MC-DIBOD ( 5 ) for cross-linking of small azides and for the protein functionalization. The applicability of this platform for the cross-linking of larger substrates was demonstrated with BSA–N 3 and PEG 5000 -azide cross-linking (Scheme ). First, PEG-azide was incubated with an equimolar amount of MC-DIBOD ( 5a ) for 12 h at room temperature.…”

Magnetic Nanoclusters Exhibiting Protein-Activated Near-Infrared Fluorescence

“…The use of a chain transfer agent (CTA) for synthesis of high molecular weight, PA-containing polymer is essential because the use of even small amounts of PA can result in cross-linked gels . During synthesis of the copolymer stabilizers, cross-linking was avoided by balancing the amount of the bifunctional PA monomer, polymerization time, and concentration of a CTA, 1-nonanethiol . The addition of CTA also benefited the tailoring of the molecular weight and polydispersity (PDI) of the synthesized polymers.…”

“…Recently, we proposed a method for the click functionalization of nanoparticles by polymerization of a clickable shell onto a polystyrene core. 23 To this end, we utilize a functional copolymer to form iron oxide nanoparticles into MNCs. Figure 1a1 presents a schematic of the procedure employed to synthesize fluorescent MNCs.…”

Different dispersion polymerization strategies influence the quality of fluorescent poly (St‐co‐GMA) microspheres

“…Polymeric microspheres have a lower density than inorganic beads, so they can remain longer in suspension, which are beneficial for automated high throughput screening (HTS). Polymeric microspheres with different range sizes can be synthesized through various polymerizations, such as emulsion polymerization, precipitation polymerization, seed polymerization, and dispersion polymerization, etc. Dispersion polymerization is an attractive method for preparing monodisperse polymeric microspheres with diameters in the range of 0.1–15 μm; and the ideal diameter of the SPA bead is approximate 5 μm, so dispersion polymerization is the optimal strategy.…”