Amorphous Se:A New Platform for Synthesizing Superparamagnetic Colloids with Controllable Surfaces

摘要

Colloidal particles have found widespread use in many areas such as chemical engineering,pharmaceutics,photonics,and biotechnology.Superparamagnetic colloids,in particular,have been actively explored in the form of nano- and microparticles for applications in biomedical separation and diagnostics,magnetic information storage,and ferrofluidic technology.For most of these applications,it is important to have good control over the surface functionalities of these colloidal particles.To this end,a number of procedures have been demonstrated to encapsulate Superparamagnetic nanoparticles (e.g.,iron oxides) in colloidal particles made of organic polymers or silica.Although these materials allow further surface modification via the use of self-assembled mono-layers (SAMs),it has been far more difficult to control the quality of resultant SAMs when compared to the system based on alkanethiols and coinage metals.For colloidal particles made of polymers or silica,it is possible to coat their surfaces with coinage metals,albeit the coating layers are usually characterized with problems such as low coverage,poor adhesion,surface roughing,and degradation in size uniformity.Here we report a new system based on amorphous selenium (a-Se) which enables the synthesis of monodispersed spherical colloids that exhibit both superpara-magnetism and controllable surfaces.