Entrapment of Biopolymers into Sol—Gel‐derived Silica Nanocomposites

Abstract

Sol-gel processing forms the basis for various routes employed for the fabrication of a wide diversity of functional materials. To impart a structural organization at various length scales, the syntheses are performed using templates. Most consist of a self-organized ensemble of surfactants and co-polymers [1-10]. They have been successfully applied to control the geometry and dimensions of pores that are periodically arranged as in the initial structures. Mesoporous silica materials of the MCM family, which were first synthesized by a team from the Mobil oil company [11,12], are a well-known example.Sol-gel processes are also widespread in the nature. The processes are called biomineralization and biosilica formation is found over a wide range from single-celled organisms to higher plants and animals [13,14]. Well-known examples of siliceous tissues are presented by diatoms and sponges. It has been demonstrated that the biomineralization or biosilicification processes in their case are completely controlled by biopolymers that regulate the size, structure, shape, spatial orientation and organization of hierarchically ordered biosilica [13][14][15][16][17][18][19][20][21][22][23][24][25]. The catalyzing and structure-driving role of biopolymers was substantiated in vitro when proteins called silicatein and silaffin, extracted, respectively, from the silica specula of sponges and the cell walls of diatoms, induced the precipitation of silica in solutions containing silicic acid or silanes at around neutral pH. Sol-gel processes did not take place in the absence of these proteins [26,27].The strong interest in biomineralization is due to its high efficiency and the superiority of the properties of biosilica over those of silica fabricated in geological processes and industrially. It proceeds at mild, ambient conditions in

Silica-based mesoporous nanoparticles for controlled drug delivery

“…Due to its simplicity, a low-cost synthesis procedure is achievable. 70,73–75 There are two main stages in the sol-gel process: hydrolysis and condensation reactions. In aqueous solution, colloidal particles are produced through hydrolysis, which can be stimulated at acidic or alkaline pH.…”

“…Orthosilicic acid was used as a silica precursor in the past, but due to the extensive time consumption and requirement of freshly prepared acid, it is not widely used anymore. 73 …”

“…However, their poor water solubility requires additional organic solvent and alcohol and needs extreme conditions of pH and high temperature, which restricts their use. 73,96,97 …”

“…This produces unique ordered mesopore channel structure, and physical characteristics of MSNs. 23,25,61,62,64,73 …”

Sol-Gel Materials with Pesticide Delivery Properties

“…Some examples are already mentioned in the literature [8,[22][23][24][25]. As the property of the sol-gel process to prepare inorganic-organic hybrids by embedding organic molecules in the inorganic oxide matrix is a well known fact [26][27][28][29][30][31][32][33][34][35], Böttcher et al [20] have used the sol-gel matrix as an alternative to biocide encapsulation. They prepared sol-gel composite films with controlled release properties.…”