Control of Structure Topology and Spatial Distribution of Biomacromolecules in Protein@ZIF-8 Biocomposites

Weibin Liang,Christopher J Sumby,Stephen G Bell,Natasha K Maddigan,Qiaowei Li,Raffaele Ricco,Robert P Dickinson,Christian J Doonan,Paolo Falcaro,Huoshu Xu

doi:10.1021/acs.chemmater.7b04977

Abstract

The protective capacity and applications of biomimetically mineralized biomacromolecule zeolitic imidazolate framework (ZIF) composites are likely dependent on the localization of the biomolecule and the topology of the mineralized ZIF coating. Herein, we identify reaction conditions to reliably yield the porous ZIF-8 sodalite topology (high ZIF-8 precursor concentrations; high 2-methylimidazole:Zn2+ ratios) in preference to other more dense phases. Furthermore, protocols to universally prepare biocomposites with a range of biomacromolecules are canvassed. Through the use of fluorophore-tagged proteins and confocal laser scanning microscopy (CLSM), we further establish the positioning of biomolecules within ZIF-8 crystals. CLSM reveals subsurface localization with fluorescein-tagged bovine serum albumin (BSA) or full encapsulation with rhodamine B-tagged BSA. These observations allowed us to demonstrate that core–shell ZIF-8 growth strategies afford complete encapsulation with varying thicknesses of poten...

Highlights

Metal-organic frameworks (MOFs) are a class of materials well-known for their high degree of crystallinity and ultra-high porosity.[1,2,3] A salient feature of MOF chemistry is that their modular synthesis from organic links and metal nodes allows for precise control of structure, pore size and chemical functionality.[4]
We studied the spatial distribution of the biomacromolecules within the zeolitic imidazolate framework (ZIF) crystals by encapsulating fluorophore-tagged bovine serum albumin (fluorescein-tagged BSA (FBSA) and rhodamine B-tagged BSA (RbBSA)) and examining them via confocal laser scanning microscopy (CLSM)
The results of the Powder X-ray diffraction (PXRD) analysis indicate that the introduction of biomacromolecules (BSA, FBSA, horseradish peroxidase (HRP), catalase, TR, HGB, AOx, lysozyme, and MB) does not affect the general trend of the product distribution observed in the ternary plot (Figure 1b and S1, and S2): i.e. that increasing the HmIM/Zn ratio leads to the lower density topology sod

Summary

Introduction

Metal-organic frameworks (MOFs) are a class of materials well-known for their high degree of crystallinity and ultra-high porosity.[1,2,3] A salient feature of MOF chemistry is that their modular synthesis from organic links and metal nodes allows for precise control of structure, pore size and chemical functionality.[4]. The phase screening protocol for the biomimetically mineralized growth of the ZIF-biocomposites were analogous to those performed in the absence of biomacromolecules (vide supra) with the exception that an aqueous solution of 1 mg of protein/enzyme (in place of water) was added to the reaction mixture (Figure 1b, S1, and S2).

Results

Conclusion