Composites of Bromobenzenethiol Functionalized Gold Nanoparticles and the Fluorescent Poly(Phenylene Ethynylene) pPET3OC12-sqS for Optical Biosensors

Abstract

Bromobenzenethiol passivated gold nanoparticles were mixed with a poly(phenylene ethynylene) bearing thioester flexible sequences in order to obtain a fluorescent composite for optical biosensors. The particles and the composite were characterized by 1H, 13C NMR, UV-Vis and fluorescence spectroscopy, TEM and STEM. The particles are homogeneously dispersed in the polymer matrix as observed by electron microscopy. The NMR spectra suggest that the gold particles and the poly(phenylene ethynylene) are probably interacting through the sulfur atoms of the –C(O)S- and –CH2-S-CH2- moieties of the flexible sequences of the polymer as well as through  interactions between the aromatic ring of 4-bromobenzenthiol and the conjugated backbone of pPET3OC12-sqS. The quantum yield of the composite both in solution and in solid state films is slightly lower than that of pPET3OC12-sqS because of the quenching effect of gold. Nonetheless, a change of the fluorescence intensity of the composite films can be detected as a consequence of the contact with microorganisms. Preliminary microbiological assays indicate an antimicrobial effect of the composite film with the E. coli bacteria.

Water-Soluble Conjugated Polymers for Imaging, Diagnosis, and Therapy

“…89 Subsequently, by using polymer 49 and bromobenzenethiolpassivated gold NPs, Moggio and co-workers prepared gold NP/PPE composites via Au−S coordination and π−π interaction between the bromobenzenethiol components and PPE backbones. 90 Another way of preparing CPNs is to impart CPs with amphiphilic structures. Water-soluble hyperbranched 27 and 114 reported by Liu and co-workers possessed hydrophobic PF internal cores and hydrophilic PEG external shells.…”

“…To combine the fluorescent property of WSCPs and the antimicrobial activity of gold NPs, Moggio and co-workers fabricated gold NP/PPE composites by blending bromobenzenethiol passivated gold NPs and PPE (49) with flexible thioester chains. 90 The proposed assembly mechanism was Au−S coordination and π−π interactions between the bromobenzenethiol components and PPE backbones. The resultant particles were uniformly dispersed and still maintained moderate fluorescent property both in solution and in solidstate film in spite of the quenching effect of gold NPs.…”

“…To combine the fluorescent property of WSCPs and the antimicrobial activity of gold NPs, Moggio and co-workers fabricated gold NP/PPE composites by blending bromobenzenethiol passivated gold NPs and PPE ( 49 ) with flexible thioester chains . The proposed assembly mechanism was Au–S coordination and π–π interactions between the bromobenzenethiol components and PPE backbones.…”

“…Facilitated by the coordinate interaction between Ag and S atoms in the polymers, Giorgetti et al fabricated fluorescent PPE derivative 49 -loaded silver NPs (Ag-CPNs) by in situ ablating a silver target in pure polymer solution . Subsequently, by using polymer 49 and bromobenzenethiol-passivated gold NPs, Moggio and co-workers prepared gold NP/PPE composites via Au–S coordination and π–π interaction between the bromobenzenethiol components and PPE backbones …”