Preparation of Functional Silica Using a Bioinspired Method

Abstract

The goal of the protocols described herein is to synthesize bioinspired silica materials, perform enzyme encapsulation therein, and partially or totally purify the same by acid elution. By combining sodium silicate with a polyfunctional bioinspired additive, silica is rapidly formed at ambient conditions upon neutralization. The effect of neutralization rate and biomolecule addition point on silica yield are investigated, and biomolecule immobilization efficiency is reported for varying addition point. In contrast to other porous silica synthesis methods, it is shown that the mild conditions required for bioinspired silica synthesis are fully compatible with the encapsulation of delicate biomolecules. Additionally, mild conditions are used across all synthesis and modification steps, making bioinspired silica a promising target for the scale-up and commercialization as both a bare material and active support medium.The synthesis is shown to be highly sensitive to conditions, i.e., the neutralization rate and final synthesis pH, however tight control over these parameters is demonstrated through the use of auto titration methods, leading to high reproducibility in reaction progression pathway and yield. Therefore, bioinspired silica is an excellent active material support choice, showing versatility towards many current applications, not limited to those demonstrated here, and potency in future applications.

Insights into the Electrochemical Reduction Products and Processes in Silica Anodes for Next‐Generation Lithium‐Ion Batteries

“…For BIS preparation, 31.82 g (0.15 moles) sodium metasilicate (Sigma‐Aldrich) was dissolved in 4650 mL deionized water, inside a 5 L Radley's reactor. [ 13 ] The solution was brought up to a mixing speed of 450 rpm, after which 5.80 g (0.025 moles) pentaethylene hexamine (PEHA) (Sigma‐Aldrich) was added to the solution. Hydrochloric acid (350 mL, 1 m ) (Sigma‐Aldrich) was added to the reaction mixture and the pH was monitored using a pH probe.…”

Mimicking Biosintering: The Identification of Highly Condensed Surfaces in Bioinspired Silica Materials

“…BIS was synthesized by room-temperature precipitation at pH 7 using PEHA as a bioinspired additive. 38 These and samples of IPS were acidified to change the surface charge and hence PEHA surface concentration in the case of BIS (see Supporting Information and ref ( 35 ) for details). Samples were therefore titrated to pH 7 (corresponding to as-made BIS), pH 5 (partial PEHA removal), and pH 2 (full PEHA removal).…”

Designing bioinspired green nanosilicas using statistical and machine learning approaches

“…13,14 Previous literature found that properties of bioinspired silica depended on multiple synthesis parameters such as the pH, the type of amine additive, the type of silicon precursor, the ratio of the concentrations of the silicon precursor and amine additive (Si : N), the reagent concentration ([Si]), and the reaction time, amongst others. 11 Generally, the silica yield increased from initially 0 to 100 mol% with decreasing Si : N ratio and increasing reaction time. [15][16][17] Small straight chain amines such as tetraethylenepentamine (TEPA), as well as polymeric ones such as poly(ethylene imine) (PEI) were found to produce yields of around 50 mol%.…”

“…Addition of acid then causes the monosilicic acid to condense and polymerise to form oligomers, which subsequently undergo growth and maturation to a solid silica "polymer" that precipitates. This method has been extensively reported and reviewed elsewhere; 2,6,8,10,11 below a brief summary of investigations relevant to the optimisation and modelling of this synthesis is provided.…”

“…[15][16][17] Small straight chain amines such as tetraethylenepentamine (TEPA), as well as polymeric ones such as poly(ethylene imine) (PEI) were found to produce yields of around 50 mol%. 11,18 Annenkov et al investigated how two different sizes of poly(vinyl amine) (PVA) affected the concentration of silicic acid monomers over a certain time range 15 and their results showed that the initial silicic acid concentration decreased with increasing reaction time. Although, a direct correlation to the yield could not be established, the data suggests that the yield generally increased with increasing reaction time.…”