Surface-Anchored Metal–Organic Framework–Cotton Material for Tunable Antibacterial Copper Delivery

Abstract

In the present study, a new copper metal-organic framework (MOF)-cotton material was strategically fabricated to exploit its antibacterial properties for postsynthetic modification (PSM) to introduce a free amine to tune the physicochemical properties of the material. A modified methodology for carboxymethylation of natural cotton was utilized to enhance the number of nucleation sites for the MOF growth. Subsequently, MOF Cu(NHBTC) was synthesized into a homogenous surface-supported film via a layer-by-layer dip-coating process. The resultant materials contained uniformly distributed 1 μm × 1 μm octahedral MOF crystals around each carboxymethylated fiber. Importantly, the accessible free amine of the MOF ligand allowed for the PSM of the MOF-cotton surface with valeric anhydride, yielding 23.5 ± 2.2% modified. The Cu ion-releasing performance of the materials was probed under biological conditions per submersion in complex media at 37 °C. Indeed, PSM induces a change in the copper flux of the material over the first 6 h. The materials continue to slowly release Cu ions beyond 24 h tested at a flux of 0.22 ± 0.003 μmol·cm·h with the unmodified MOF-cotton and at 0.25 ± 0.004 μmol·cm·h with the modified MOF-cotton. The antibacterial activity of the material was explored using Escherichia coli by testing the planktonic and attached bacteria under a variety of conditions. MOF-cotton materials elicit antibacterial effects, yielding a 4-log reduction or greater, after 24 h of exposure. Additionally, the MOF-cotton materials inhibit the attachment of bacteria, under both dry and wet conditions. A material of this type would be ideal for clothing, bandages, and other textile applications. As such, this work serves as a precedence toward developing uniform, tunable MOF-composite textile materials that can kill bacteria and prevent the attachment of bacteria to the surface.

Recent advances in process engineering and upcoming applications of metal–organic frameworks

“…In order to prepare antibacterial surfaces that can prevent bacterial growth, a new cotton/MOF composite material (Cu 3 (NH 2 BTC) 2 MOF-cotton) was developed that exhibited excellent antibacterial activity toward E. coli [310] . Substantially, a copper-based MOF was attached on cotton by a post-synthetic modification process, resulting in AM-5-modified MOF ( Fig.…”

Omniphobic ZIF‐8@Hydrogel Membrane by Microfluidic‐Emulsion‐Templating Method for Wound Healing

“…To trap MOFs in omniphobic hydrogel, wound dressing not only protects MOFs from degradation in physiological fluids, but also prevents the burst release of metal ions that could be toxic 25,27–29. In addition to their bactericidal and anti‐inflammatory properties, the slowly released copper and zinc ions have shown to accelerate wound healing by promoting cell migration, angiogenesis, and collagen deposition 25,28,29,32,33. Benefiting from a microfluidic‐emulsion‐templated method, we successfully encapsulate a model example of MOFs, zeolitic imidazolate framework‐8 (ZIF‐8), in a well‐defined porous polyvinyl alcohol (PVA) hydrogel membrane with exquisite reentrant microstructures 20,21,34,35.…”

“…MOFs are used as bactericidal agents; they are crystalline porous coordination polymers that can store and release metal ions slowly, such as zinc, copper, and cobalt ions. [25][26][27][28][29][30][31][32] To trap MOFs in omniphobic hydrogel, wound dressing not only protects MOFs from degradation in physiological fluids, but also prevents the burst release of metal ions that could be toxic. [25,[27][28][29] In addition to their bactericidal and anti-inflammatory properties, the slowly released copper and zinc ions have shown to accelerate wound healing by promoting cell migration, angiogenesis, and collagen deposition.…”

“…[25,[27][28][29] In addition to their bactericidal and anti-inflammatory properties, the slowly released copper and zinc ions have shown to accelerate wound healing by promoting cell migration, angiogenesis, and collagen deposition. [25,28,29,32,33] Benefiting from a microfluidic-emulsion-templated method, we successfully encapsulate a model example of MOFs, zeolitic imidazolate framework-8 (ZIF-8), in a well-defined porous polyvinyl alcohol (PVA) hydrogel membrane with exquisite reentrant microstructures. [20,21,34,35] The resultant MOFs@PVA composite hydrogel membrane exhibits a large apparent CA of 120° for physiological fluids.…”

“…In this work, we present an omniphobic wound dressing made from metal‐organic frameworks (MOFs) composite hydrogels. MOFs are used as bactericidal agents; they are crystalline porous coordination polymers that can store and release metal ions slowly, such as zinc, copper, and cobalt ions 25–32. To trap MOFs in omniphobic hydrogel, wound dressing not only protects MOFs from degradation in physiological fluids, but also prevents the burst release of metal ions that could be toxic 25,27–29.…”