Polydopamine Microcapsules with Different Wall Structures Prepared by a Template-Mediated Method for Enzyme Immobilization

Abstract

Microcapsules with diverse wall structures may exhibit different performance in specific applications. In the present study, three kinds of mussel-inspired polydopamine (PDA) microcapsules with different wall structures have been prepared by a template-mediated method. More specifically, three types of CaCO3 microspheres (poly(allylamine hydrochloride), (PAH)-doped CaCO3; pure-CaCO3; and poly(styrene sulfonate sodium), (PSS)-doped CaCO3) were synthesized as sacrificial templates, which were then treated by dopamine to obtain the corresponding PDA-CaCO3 microspheres. Through treating these microspheres with disodium ethylene diamine tetraacetic acid (EDTA-2Na) to remove CaCO3, three types of PDA microcapsules were acquired: that was (1) PAH-PDA microcapsule with a thick (∼600 nm) and highly porous capsule wall composed of interconnected networks, (2) pure-PDA microcapsule with a thick (∼600 nm) and less porous capsule wall, (3) PSS-PDA microcapsule with a thin (∼70 nm) and dense capsule wall. Several characterizations confirmed that a higher degree in porosity and interconnectivity of the capsule wall would lead to a higher mass transfer coefficient. When serving as the carrier for catalase (CAT) immobilization, these enzyme-encapsulated PDA microcapsules showed distinct structure-related activity and stability. In particular, PAH-PDA microcapsules with a wall of highly interconnected networks displayed several significant advantages, including increases in enzyme encapsulation efficiency and enzyme activity/stability and a decrease in enzyme leaching in comparison with other two types of PDA microcapsules. Besides, this hierarchically structured PAH-PDA microcapsule may find other promising applications in biocatalysis, biosensors, drug delivery, etc.

Anisotropic polydopamine capsules with an ellipsoidal shape that can tolerate harsh conditions: efficient adsorbents for organic dyes and precursors for ellipsoidal hollow carbon particles

“…3,4,33,37,38,[45][46][47] Herein, three kinds of PS ellipsoids prepared from a well-known thermostretching method were used as the templates:…”

“…Even so, PDA capsules are oen in the bulked or collapsed state aer airdrying, indicating a moderate mechanical strength. 4,6,7,9,10,12,22,37,38 Especially, although PDA have emerged as a very attractive precursor for nitrogen-doped carbon materials, preparation of hollow carbon particles or carbon capsules by carbonization of PDA involves multiple steps including PDA coating of hard templates, carbonization and template removing. 30,31,33,34 Carbonization of PDA coated templates might lead to the contamination of the carbon materials by the underlying templating materials, which can be avoid by direct carbonization of pure PDA capsules into carbon capsules.…”

Polydopamine used as Hollow Capsule and Core–Shell Structures for Multiple Applications

“…In particular, PAH-PDA microcapsules displayed several signi¯cant advantages, including increases in enzyme encapsulation e±ciency and enzyme activity/stability and a decrease in enzyme leaching in comparison with other two types. 114 Developed new methods to prevent the leaching of enzyme were reported later. More speci¯cally, two approaches for enzyme-containing PDA-SiO 2 hybrid materials were explored.…”

Electroresponsive and cell-affinitive polydopamine/polypyrrole composite microcapsules with a dual-function of on-demand drug delivery and cell stimulation for electrical therapy

“…19,20 PDA-MCs are generally prepared by coating PDA on sacrificial templates, such as silica (SiO 2 ) particles, PS-MS and calcium carbonate particles. 21,22 Cui et al 19 prepared PDA-MCs using a dimethyldiethoxysilane emulsion template and used PDA-MCs for loading doxorubicin. Wang et al 23 used PS-MS as a template to fabricate PDA-MC layer-by-layer films and then immobilized bone morphogenetic protein-2 on the PDA-MC surfaces.…”