Thiol surface biofunctionalization

Traditionally, inorganic silica nanoparticles have been prepared from either TEOS (1) or tetramethoxyorthosilicate (TMOS) (2). When prepared, TEOS nanoparticles are composed internally of a simple silica network (—O—Si—O—), and have silanol groups on their surfaces. However, as they lack any exposed organic residues, both inside and on their surfaces (as shown schemahcally in Figure 4.1), they will require further modification with funchonal residues (e.g. amine or thiol) prior to their surface biofunctionalization. 

Direct attachment of proteins and peptides to the Qdot surface is based on two types of Qdot surface protein interactions dative thiol-bonding between Qdot surface sulfur atoms and cysteine residues and metal-affinity coordination of histidine (HIS) residues to the Qdot surface Zn atoms (Fig. 17.3(c)). The Weiss group demonstrated the former by using phytochelatin-related peptides to cap CdSe/ZnS (core/shell) Qdots, providing not only surface passivation and water solubility, but also a point of biochemical modification. Using peptides for both dispersion and biofunctionalization represents a new class of rationally designed multifunctional biological cap. ... 

---