Iodine Immobilized UiO-66-NH2 Metal-Organic Framework as an Effective Antibacterial Additive for Poly(ε-caprolactone).

Wei Chen,Yating Chen,Chunsheng Wu,Ping Zhu,Liping Du,Yage Liu

doi:10.3390/polym14020283

Abstract

Iodine has been widely used as an effective disinfectant with broad-spectrum antimicrobial potency. However, the application of iodine in an antibacterial polymer remains challenging due to its volatile nature and poor solubility. Herein, iodine immobilized UiO-66-NH2 metal-organic framework (MOF) (UiO66@I2) with a high loading capacity was synthesized and used as an effective antibacterial additive for poly(ε-caprolactone) (PCL). An orthogonal design approach was used to achieve the optimal experiments’ conditions in iodine adsorption. UiO66@I2 nanoparticles were added to the PCL matrix under ultrasonic vibration and evaporated the solvent to get a polymer membrane. The composites were characterized by SEM, XRD, FTIR, and static contact angle analysis. UiO-66-NH2 nanoparticles have a high iodine loading capacity, up to 18 wt.%. The concentration of iodine is the most important factor in iodine adsorption. Adding 0.5 wt.% or 1.0 wt.% (equivalent iodine content) of UiO66@I2 to the PCL matrix had no influence on the structure of PCL but reduces the static water angle. The PCL composites showed strong antibacterial activities against Staphylococcus aureus and Escherichia coli. In contrast, the same content of free iodine/PCL composites had no antibacterial activity. The difference in the antibacterial performance was due to the different iodine contents in the polymer composites. It was found that MOF nanoparticles could retain most of the iodine during the sample preparation and storage, while there was few iodine left in the free iodine/PCL composites. This study offers a common and simple way to immobilize iodine and prepare antibacterial polymers with low antiseptic content that would reduce the influence of an additive on polymers’ physical properties.

Highlights

Metal-organic frameworks (MOFs), or coordination polymers, are a novel type of highly porous materials with a crystalline structure [1]
The surface of Zr-MOF was occupied by the iodine molecules, which would be caused by the high surface energy and the coordination bonds between Zr and iodine
The MOF nanoparticles in the PCL had some aggregations because of the surface occupied by iodine molecules

Summary

Introduction

Metal-organic frameworks (MOFs), or coordination polymers, are a novel type of highly porous materials with a crystalline structure [1]. The incorporation of MOFs into a polymer as mixed-matrix membranes provides a solution to manipulate and process the crystalline and robust MOFs [8,9]. The composite combines the molecular sieving effect of MOFs but overcomes the brittleness, accelerating the molecular separation and industrial application. In separation fields, MOFs/polymer composite could be used as an antibacterial material. UiO-66 and MOF-525 nanoparticles disperse uniformly in poly(εcaprolactone) (PCL) even in a high loading capacity [10]. The mixed-matrix membranes exhibit the integrity of the pore structure of UiO-66 through dye separation. The MOF525/PCL membrane shows effective antibacterial activity against Escherichia coli by the generation of reactive oxygen species. The open Zr site of UiO-66 improved the adhesion on the interface of the PCL matrix

Methods

Results

Conclusion