Chain length of bioinspired polyamines affects size and condensation of monodisperse silica particles

Abstract

Polyamines play a major role in biosilicification reactions in diatoms and sponges. While the effects of polyamines on silicic acid oligomerization and precipitation are well known, the impact of polyamines chain length on silica particle growth is unclear. We studied the effects of polyamine chain length on silica particle growth and condensation in a known, simple, and salt-free biphasic reaction system; with tetraethyl orthosilicate as organic phase and polyamine dissolved in the aqueous phase. The particles at various growth stages were characterized by Cryo- Transmission Electron Microscopy, Scanning Electron Microscopy, Thermogravimetric Analysis, Zeta Potential, and solid-state NMR analysis. Polyamines were found co-localized within silica particles and the particle diameter increased with an increase in polyamine chain length, whereas silica condensation showed the opposite trend. Particle growth is proposed to progress via a coacervate intermediate while the final particles have a core shell structure with an amine-rich core and silica-rich shell. The results presented in this paper would of interest for researchers working in the field of bioinspired materials.

Hysteresis‐Free, Elastic, and Tough Hydrogel with Stretch‐Rate Independence and High Stability in Physiological Conditions

“…[33,34] Polyamine colloids, a complex of polyallylamine hydrochloride (PAH) and phosphate ion (Pi), promoted the polycondensation of silicic acid. [35,36] Consequently, rough BM-silica NPs with a surface of embedded circular PAH chains in 300-400 nm diameter were synthesized (Figure 2a), which is contrary to the smooth surfaces typically observed in C-silica NPs (Figure 2b). A detailed synthesis process is described in the Experimental Section.…”

Biomimetic Sol–Gel Chemistry to Tailor Structure, Properties, and Functionality of Bionanocomposites by Biopolymers and Cells

“…It should be noted that studies by Patwardhan et al, Livage et al, and Naik et al, as well as other authors [ 5 , 76 , 135 , 136 , 137 , 138 , 139 , 140 , 141 , 142 , 143 , 144 , 145 , 146 , 147 , 148 ], were carried out in neutral solutions, but they took pre-prepared silica sols obtained by hydrolysis of TEOS or TMOS. When TEOS was used in the experiment without preliminary hydrolysis, 90% of the calculated amount of SiO 2 in the presence of polylysine at pH 6.9 was formed only after ~20 days [ 149 ].…”

“…Copolypeptides self-assembled into aggregates which determined the hydrolysis of TEOS and the formation of SiO 2 of different morphology; • Patwardhan et al, in a series of papers [124][125][126][127][128][129][130], showed that cationic polymers and peptides, including poly-lysine, -arginine, -histidine, -allylamine, and -amine, catalyzed the sol-gel transition in solution with preformed SiO 2 sol, acting as the template They obtained spherical particles having fiber-like and ladder-shaped silica morphologies with periodic voids; • Livage and coworkers independently obtained similar results with polylysine and polyarginine [131,132], as well as with an arginine-containing surfactant [133]. They observed the gelation of solutions containing silica oligomers and the precipitation of silica sols; [5,76,[135][136][137][138][139][140][141][142][143][144][145][146][147][148], were carried out in neutral solutions, but they took pre-prepared silica sols obtained by hydrolysis of TEOS or TMOS. When TEOS was used in the experiment without preliminary hydrolysis, 90% of the calculated amount of SiO 2 in the presence of polylysine at pH 6.9 was formed only after ~20 days [149].…”

Polymer-Rich Dense Phase Can Concentrate Metastable Silica Precursors and Regulate Their Mineralization

“…It is attractive to study the involvement of liquid–liquid phase separation in mineralization processes, as both phenomena fundamentally involve phase transitions. − One of the most intriguing examples is the formation of silica at physiological conditions within cells, a process that is extremely different from the harsh chemical conditions that are used in industrial silica applications . A hallmark of biogenic silicification processes is the presence of oppositely charged polymers, cationic long-chain polyamines, and negatively charged proteins, that can phase separate, forming a dense polymer-rich phase, or a coacervate, within a dilute matrix. − Several bioinspired silicification experiments suggested that liquid–liquid phase separation is involved in various stages of the process, − albeit not as a mandatory feature . But even though it was recently demonstrated that the polymer dense phase creates a distinct chemical environment that facilitates the formation of dense silica particles, the microscopic size of the dense phase droplets precluded the ability to elucidate the chemistry that leads to the regulated silicification process.…”

“… 19 A hallmark of biogenic silicification processes is the presence of oppositely charged polymers, cationic long-chain polyamines, and negatively charged proteins, that can phase separate, forming a dense polymer-rich phase, or a coacervate, within a dilute matrix. 20 − 22 Several bioinspired silicification experiments suggested that liquid–liquid phase separation is involved in various stages of the process, 23 − 25 albeit not as a mandatory feature. 26 But even though it was recently demonstrated that the polymer dense phase creates a distinct chemical environment that facilitates the formation of dense silica particles, 27 the microscopic size of the dense phase droplets precluded the ability to elucidate the chemistry that leads to the regulated silicification process.…”