Synthesis and Characterization of Active Ester-Functionalized Polypyrrole−Silica Nanoparticles:  Application to the Covalent Attachment of Proteins

Abstract

Novel ester-functionalized polypyrrole−silica nanocomposite particles were prepared by oxidative copolymerization of pyrrole and N-succinimidyl ester pyrrole (50/50% initial concentrations), using FeCl3 in the presence of ultrafine silica nanoparticles (20 nm diameter). The N-succinimidyl ester pyrrole monomer was prepared in aqueous solution using 1-(2-carboxyethylpyrrole) and N-hydroxysuccinimide in the presence of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide. The resulting nanocomposites (N-succinimidyl ester polypyrrole−silica) are raspberry-shaped agglomerates of silica sol particles “glued” together by the insoluble poly(pyrrole-co-N-succinimidyl pyrrole). The N-succinimidyl ester polypyrrole−silica particles were characterized in terms of their size, density, copolymer content, and polydispersity. Scanning electron microscopy and disk centrifuge sedimentometry confirmed that the nanocomposite particles had narrow size distributions. X-ray photoelectron spectroscopy analysis indicated a silica-rich surface and a high surface concentration of N-succinimidyl ester groups. These nanoparticles exhibited good long-term dispersion stability. The chemical stability of the ester functions in aqueous media after several weeks of storage was monitored by FTIR spectroscopy. The functionalized nanocomposites were tested as bioadsorbents of human serum albumin (HSA). The very high amount of immobilized HSA determined by UV−visible spectroscopy is believed to be due to covalent binding. Incubation of the HSA-grafted nanocomposite with anti-HSA resulted in immediate flocculation, an indication that they are alternative candidates for visual diagnostic assays.

Neuroactive conducting scaffolds: nerve growth factor conjugation on active ester-functionalized polypyrrole

“…The IR spectra of (3) showed peaks of the succinimidyl ester groups and pyrrolidinone groups at 1740, 1782 and 1814 cm K1 . The results were in good agreement with the published literature (Azioune et al 2004;Bousalem et al 2004;Khan et al 2006).…”

“…For example, PPy-NSE 75 is prepared in a solution of 12.5 mM pyrrole and 37.5 mM pyrrole-NSE. Azioune et al 2004;Bousalem et al 2004). Fifty microlitres of NGF solution (20 mg ml K1 in 0.1 M PBS, pH 7.2) were loaded on the 1 cm 2 sample piece.…”

Synthesis and characterisation of sterically stabilised polypyrrole particles using a chemically reactive poly(vinyl amine)-based stabiliser

“…This hypothesis is supported by the 50 observation that NaBH 4 reduction of these imine bonds to generate more hydrolytically stable secondary amine bonds prior to the synthesis of polypyrrole particles appears to be beneficial. In principle, the primary amine groups on the surface of these polypyrrole particles should allow facile conjugation of bio-55 markers for immunodiagnostics applications [11,[21][22][23].…”

The increasing importance of carbon nanotubes and nanostructured conducting polymers in biosensors

“…An example of this is where functionalised silicaPPy nanocomposites were used to detect anti-HSA. Flocculation of the nanocomposite dispersion occurs upon anti-HSA binding and the system can therefore be used for visual diagnostic assays (132). Human serum albumin (HSA) is of interest as a target as it was previously used to detect renal disease.…”