Large Pore Mesoporous Silica Nanoparticles by Templating with a Nonsurfactant Molecule, Tannic Acid

Abstract

We describe a one-pot synthesis of novel large-pore mesoporous silica nanoparticles using a nonsurfactant template, tannic acid, and protein immobilization on these particles. The tannic-acid-templated mesoporous silica nanoparticles (TA-MSNPs) possess tunable large pores (6−13 nm), unique pore morphology, and a uniform diameter of ca. 200 nm. TA-MSNPs show high protein adsorption capacity of 77.1 mg/g for lysozyme, 396.5 mg/g for bovine hemoglobin, and 130.0 mg/g for bovine serum albumin and rapid protein uptake. They can also adsorb a large amount of m-MDH (421 ± 13 mg/ g) and protect this enzyme from the environment, as demonstrated by its high activity when encapsulated inside the mesopores of TA-MSNPs. ■. INTRODUCTIONMesoporous silica nanoparticles (MSNPs) attract increasing attention because of their high surface area, hydrophilic and easily functionalized surface, and biocompatibility. These properties are of high interest for a host of applications, 1,2 including drug delivery, 3 imaging, 4−6 catalysis, 7,8 and sensing. 9 To fulfill this promise, especially in the biomedical area, monodisperse MSNPs with sizes in the 50−200 nm range (to facilitate cell uptake 10,11 ) and with large mesopores (to allow for the encapsulation of biomacromolecules) are desired. In addition, accessible internal volume resulting from interconnected pores would be beneficial for these applications. 12,13 Numerous strategies for the preparation of MSNPs have been developed 14 using templating agents, usually surfactants. 15 Ionic surfactants, such as cetyltrimethylammonium bromide (CTAB), self-assemble into micelles, which create the voids in the silica matrix during the preparation of mesoporous silica materials, such as MCM-41. The formation of the mesoporous structure of MCM-41 is mainly due to the electrostatic interactions between the ionic surfactant and silicate species. 15 For nonionic surfactants, such as triblock copolymers, the hydrogen bonding between the surfactants and the silicate is believed to be the main driving force in the formation of mesoporous silica materials, such as SBA-15. 15 Fluorocarbon surfactants were also used to synthesize mesoporous silica with improved stability and novel mesostructures. 16 In all these cases, templating surfactant agents lead to ordered structures with noninterconnected cylindrical pores. 15 Several synthetic protocols for MSNPs with particle diameter and pore size controlled by using various surfactants and swelling agents have been reported. 12−19 For example, MCM-41 nanoparticles can be prepared with diameters in the 30−280 nm range; 20 however, the maximum pore size is limited to ca. 6 nm. SBA-15 nanoparticles 21 contain mesopores of larger sizes, controlled by triblock-copolymer templates, cosolvents, and swelling agents in the range of 6 to 50 nm. However, the size of the smallest SBA-15 particles reported so far is around 500 nm. 5,22 It remains a challenge to produce uniform MSNPs with diameters smaller than 200 nm and pore size larger than 10 nm in a simple synthetic p...

Improved Performance of Lipase Immobilized on Tannic Acid-Templated Mesoporous Silica Nanoparticles

“…2, nitrogen sorption isotherms of TA-MSNs exhibited a typical type IV curve with a hysteresis loop between H 2 -type and H 3 -type [38] at a relative pressure (p/p 0 ) range of 0.4-1.0, suggesting the formation of open-slit mesopores. The BET surface area of the TA-MSNs is 447 m 2 /g, and the pore volume is about 0.91 cm 3 /g, which is consistent with the previous report [8]. The pore size distribution curve derived from the adsorption branch using the BJH model confirmed the presence of mesopores in TA-MSNs, and the mean mesopore sizes of the sample was ca.…”

Biodegradable Magnetic Silica@Iron Oxide Nanovectors with Ultra-Large Mesopores for High Protein Loading, Magnetothermal Release, and Delivery

“…[52] Silica NPs with pore sizes ranging from 5 nm up to 40 nm have been utilized to load proteins of various molecular weights from cytochrome C (12 kDa) to immunoglobulin G (150 kDa). [53][54][55][56][57][58][59] Iron oxide@mesoporous silica NPs with 5-9 nm [60] and 10-15 nm [61] pores were also developed and loaded with biomolecules of sizes below 4 nm. [52] The large pore sizes available with the elaboration of novel inorganic…”

Fabrication and characterization of novel shape-stabilized stearic acid composite phase change materials with tannic-acid-templated mesoporous silica nanoparticles for thermal energy storage

“…The formation of the special morphology of the TAMSN particles was mainly attributed to the electrostatic interactions and hydrogen bonding between the silicate species and supramolecular tannic acid. 23 The protonated hydroxyl groups of tannic acid could undergo hydrogen bond formation with the silicate particles from TEOS, which contributed to the formation of the substantial complex, and then, with the removal of the tannic acid from the complex, the particles connected through reticular formation, and the TAMSN particles with a special morphology were formed. 23 The SEM images of SA/TAMSN are shown in Fig.…”

“…23 The protonated hydroxyl groups of tannic acid could undergo hydrogen bond formation with the silicate particles from TEOS, which contributed to the formation of the substantial complex, and then, with the removal of the tannic acid from the complex, the particles connected through reticular formation, and the TAMSN particles with a special morphology were formed. 23 The SEM images of SA/TAMSN are shown in Fig. 2, and it can be seen that aer stearic acid was adsorbed on the mesoporous material; the surface of SA/TAMSN became gelatinous, and the structures of the particles became colloidal and overlapping, indicating that stearic acid was fully adsorbed on the TAMSNs.…”

“…Therefore, it is necessary to develop a new template with properties of low cost, non-toxicity and being easy to remove. Recently, Zharov et al 23 put forward a expedient way to prepare mesoporous silica materials by using tannic acid as a template. Tannic acid is a glucoside polymer of gallic acid and has multiple phenolic hydroxyl groups.…”