One pot microwave assisted synthesis of bisphosphonate alkene capped gold nanoparticles

Abstract

International audienceA new synthetic pathway for the direct synthesis of water soluble gold nanoparticles (GNPs) already possessing terminal alkene functional groups was developed. This is achieved by using synthesized (1-hydroxy-1-phosphonopent-4-enyl)phosphonic acid (HMBPene), presenting advantages of the well known bisphosphonate coating applied to colloidal gold instead of metal oxides. The proposed protocol allowed an accurate control of the particle size in the 13–20 nm diameter range with a high spherical uniformity, which is a crucial point for these colloids' properties. We have shown that it is possible to synthesize a functionalized nanoplatform in a one-pot one-phase process with a sacrificial molecule as reductant, pH mediator and capping agent

Tetrazine Click Chemistry for the Modification of 1‐Hydroxy‐1,1‐methylenebisphosphonic Acids: Towards Bio‐orthogonal Functionalization of Gold Nanoparticles

“…We then transpose this reaction onto our Au@HMBPene nanoparticles (NPs). These NPs are obtained by a slightly modified protocol inspired of the one‐pot synthesis recently described . Briefly 4.4 equivalents of HMBPene was added to a chloauric acid solution (1 m m ) brought to boil in deionized water for 10 min without any other reactant.…”

“…Our concern was that the reaction rate of tetrazines with linear alkenes is scarcely described and shown to be, in the literature, about two orders of magnitude lower than strained alkene such as norboren or cycloocten derivatives . The chosen HMBP was the (1‐hydroxy‐1‐phosphonopent‐4‐enyl)phosphonic acid (HMBPene) obtained following the protocol previously described . It was reacted with 3,6‐dipyridin‐2‐yl‐1,2,4,5‐tetrazine (pyTz) in pure water.…”

“…For example, in the course of the last 8 years we developed HMBP‐coated iron oxide nanoparticles bearing carboxylate, amine and alkyne functionality and evaluate their modification through carbodiimide chemistry, copper alkyne azide cycloaddition (CuAAC) and thiol‐yne chemistry . Recently, we and others have demonstrated that HMBP could also be of great interest for the “one‐pot” synthesis and coating of gold and silver nanoparticles . In the case of gold nanoparticle synthesis, not only do the molecules permit the stabilization of the formed metallic nanoparticles but they also act as the reducing agent allowing their formation.…”

“…[25][26][27][28][29][30] Recently,w ea nd others have demonstrated that HMBP could also be of great interestf or the "one-pot" synthesis and coating of gold and silver nanoparticles. [31,32] In the case of gold nanoparticle synthesis, not only do the molecules permit the stabilization of the formed metallic nanoparticles but they also act as the reducing agent allowing their formation.T his synthesis,w hich follows am echanism related to the well-known Turkevich-Frens synthesis, produced variable sizes of relatively monodispersed nanoparticles. Moreover,t he nanoparticles present at their surface, an alkene functionality that could potentially be used for their post-functionalizationb yc lick chemistry.The concepto fc lick chemistry originally proposed by Sharpless et al [33] has become highly popular and found many applicationsi nn anomaterial functionalization [34,35] for grafting in mild conditions (especially in biological media) and in achemoselectivem anner aw ide range of molecules at the surface.…”

“…[50,51] The chosen HMBPw as the (1-hydroxy-1-phosphonopent-4-enyl)phosphonic acid (HMBPene)o btained following the protocol previously described. [31] It was reactedw ith 3,6-dipyridin-2-yl-1,2,4,5-tetrazine (pyTz) in pure water.T he reactionw as followed by 31 PNMR and optimized varying pyTz concentration,p H, reaction time and temperature. Complete conversion (no HMBPene remaining in solution) was obtained after 24 ha tr oom temperatureu sing 2equiv.o fp yTz at pH < 1t oe nsure its solubilisation in ar elatively concentrated solution.D ecreaseo ft he pyTz quantity or decrease of the reaction time resultedi nu ncomplete reaction.…”