Polysaccharides are the most abundant macromolecules in nature, and their property are well known in scientific and industrial field1. An increasing number of studies is currently exploring the properties of nanoparticles with polysaccharides for a virtually unlimited number of applications (drug delivery, imaging, new materials science et.). In this context nanoparticles functionalized anisotropically are even more attractive for their peculiar characteristics such as hierarchical self-assembling and tunable amphiphilicity. This work was focused on the evaluation of the most efficient grafting reaction between polysaccharides and silica nanoparticles, with the aim to prepare Janus particles with the largest superficial concentration of macromolecules. Dextran and amylose were selected for this study. The former is a linear ?-D-1,6-glucose-linked glucan water soluble, and the latter is the water-unsoluble component of starch constituted by ?-D-1,4-glucose units. In order to graft polysaccharides on funzionalized silica Janus particles two well known coupling reactions were compared: reductive amination with aldehyde1 and Cu(I) catalyzed azide-alkyne cycloaddtion (CuAAc)2. The reductive amination reaction was carried out between amine groups on silica Janus particles3 and aldehydes groups on polysaccharides. Either natural occurring aldehyde at the reducing chain-end of the polysaccharide or aldehydes groups produced by oxidation along the polymer backbone were exploited. CuAAc reaction was carried out between dextran or amylose bearing alkyne moieties and azidated Janus particles. All prepared Janus Particles were characterized by spectroscopic analysis, calorimetry and the grafting degree was evaluated by spectrophotometric titration. The effective dual nature of Janus particles was assed by TEM analysis with selective staining, exploiting the different interactions among the strainer agents and the modified particles surfaces.
Reductive Amination Vs "Click" Reaction On The Grafting Of Polysaccharides Onto Janus Silica
D Barsi;M Corricelli;M L Curri;M Bertoldo
2017
Abstract
Polysaccharides are the most abundant macromolecules in nature, and their property are well known in scientific and industrial field1. An increasing number of studies is currently exploring the properties of nanoparticles with polysaccharides for a virtually unlimited number of applications (drug delivery, imaging, new materials science et.). In this context nanoparticles functionalized anisotropically are even more attractive for their peculiar characteristics such as hierarchical self-assembling and tunable amphiphilicity. This work was focused on the evaluation of the most efficient grafting reaction between polysaccharides and silica nanoparticles, with the aim to prepare Janus particles with the largest superficial concentration of macromolecules. Dextran and amylose were selected for this study. The former is a linear ?-D-1,6-glucose-linked glucan water soluble, and the latter is the water-unsoluble component of starch constituted by ?-D-1,4-glucose units. In order to graft polysaccharides on funzionalized silica Janus particles two well known coupling reactions were compared: reductive amination with aldehyde1 and Cu(I) catalyzed azide-alkyne cycloaddtion (CuAAc)2. The reductive amination reaction was carried out between amine groups on silica Janus particles3 and aldehydes groups on polysaccharides. Either natural occurring aldehyde at the reducing chain-end of the polysaccharide or aldehydes groups produced by oxidation along the polymer backbone were exploited. CuAAc reaction was carried out between dextran or amylose bearing alkyne moieties and azidated Janus particles. All prepared Janus Particles were characterized by spectroscopic analysis, calorimetry and the grafting degree was evaluated by spectrophotometric titration. The effective dual nature of Janus particles was assed by TEM analysis with selective staining, exploiting the different interactions among the strainer agents and the modified particles surfaces.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
