High-Density Protein Loading on Hierarchically Porous Layered Double Hydroxide Composites with a Rational Mesostructure

Abstract

Hierarchically porous biocompatible Mg-Al-Cl-type layered double hydroxide (LDH) composites containing aluminum hydroxide (Alhy) have been prepared using a phase-separation process. The sol-gel synthesis allows for the hierarchical pores of the LDH-Alhy composites to be tuned, leading to a high specific solid surface area per unit volume available for high-molecular-weight protein adsorptions. A linear relationship between the effective surface area, SEFF, and loading capacity of a model protein, bovine serum albumin (BSA), is established following successful control of the structure of the LDH-Alhy composite. The threshold of the mean pore diameter, Dpm, above which BSA is effectively adsorbed on the surface of LDH-Alhy composites, is deduced as 20 nm. In particular, LDH-Alhy composite aerogels obtained via supercritical drying exhibit an extremely high capacity for protein loading (996 mg/g) as a result of a large mean mesopore diameter (>30 nm). The protein loading on LDH-Alhy is >14 times that of a reference LDH material (70 mg/g) prepared via a standard procedure. Importantly, BSA molecules pre-adsorbed on porous composites were successfully released on soaking in ionic solutions (HPO4(2-) and Cl(-) aqueous). The superior capability of the biocompatible LDH materials for loading, encapsulation, and releasing large quantities of proteins was clearly demonstrated.

Aqueous synthesis of metal hydroxides with controllable nano/macro architectures

“…7) The metal hydroxide materials overviewed in the previous sections possess specific macro and meso structures, and thereby, exhibit characteristic chemical/physical properties. The author and co-authors have reported the enhancement of dye adsorption 35) and protein adsorption 53) on hierarchically porous MgAl LDH. In the case of dye adsorption (Rhodamine B and Pyranine), larger macropores resulted in faster adsorption on LDH.…”

3D hierarchical and porous layered double hydroxide structures: an overview of synthesis methods and applications

“…In limiting the capillary forces which occur during drying, supercritical drying is well-known as an efficient process to produce highly porous aerogels [45]. LDH aerogels were produced using LDH wet physical gels by applying water exchange with a non-aqueous solvent and subsequent CO2 supercritical drying [46,47]. Even if monoliths are not systematically obtained, such treatment induces a net increase of the mesoporosity compared to standard ambient drying.…”

“…The introduction of porosity, especially large mesopores and/or macropores, can increases the surface area which is accessible by large biomolecules with tens nm in size. High-density protein loading on porous LDH was reported for trypsine [47] and bovine serum albumin (BSA) [46,121], where enhancement of adsorption were reported as 20 times and 14 times compared to those for standard LDH, respectively (Table 6). There has been also various reports on loading and releasing an antibiotic [85], drug [128], enzyme [47], glucose biosensor development [122,134] and tissue-engineering scaffolds [49].…”

Development of Mesopore Structure of Mixed Metal Oxide through Albumin-Templated Coprecipitation and Reconstruction of Layered Double Hydroxide

“…Similarly, CeO 2 catalyst or nanosized NiO could be synthesized through sacrificial template of albumin [41,42]. Deoxyribonucleic acid was utilized to prepare Co 9 S 8 nanoparticles with mesoporous internal structure [43], or to synthesize porous transition metal oxide [44]. It was also reported that porous alumina was obtained by collagen.…”