Loading and Sustained Release of Benzyl Ammonium Chloride (BAC) in Nano-Clays.

Benzyl ammonium chloride (BAC) is a broad-spectrum bactericide, but vulnerable to leaching by water. In this paper, halloysite nanotubes (HNT) and montmorillonite (MMT) were used as drug carriers to load BAC, in order to achieve good anti-mildew activity and long-term sustained release properties. The HNT and MMT nano-composites were characterized by transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and nitrogen adsorption/desorption. XRD results showed that BAC intercalated the interlayer of MMT, and expanded the interlayer spacing from 1.15 nm to 1.75 nm. Pore analysis showed that BAC decreased the cavity of halloysite nanotubes to a certain extent, which indicated that BAC loaded inside the lumen of HNT successfully. TG analysis showed that the loading capacity of MMT to BAC was higher than HNT. The accelerated-release experiments revealed both two clays have significant sustained-release effects on BAC, and the releasing rate of HNT was relatively lower. Both HNT and MMT have promising application prospects as sustained-release carriers. The inhibition test showed that BAC in nano-clay has good anti-mildew resistance performance.

In situ deposition of MOF199 onto hierarchical structures of bamboo and wood and their antibacterial properties.

Tremendous efforts have been dedicated to developing functionalized cellulose materials by synthesis with copper-based metal-organic frameworks (MOF199), also known as HKUST-1. However, few studies have explored the deposition of MOFs on woody materials due to the complex chemical compositions of these materials (cellulose, hemicellulose, lignin) and their difficulty of bonding with MOF crystals. In this article, for the first time, MOF199 was successfully synthesized onto two different woody materials, moso bamboo and balsa wood, via in situ deposition at room temperature. The results show that the diverse surface roughness and the hierarchical structures of woody materials have significant effects on the size of MOF199 crystal. Additionally, bamboo and wood coated with MOF199 exhibited better antibacterial activities against Staphylococcus aureus (S. aureus) than Escherichia coli (E. coli); they could minimize S. aureus colony levels to 2.08 from 8.98 CFU cm-2. This study provides a facile method for the functionalization of woody materials with MOFs for antibacterial applications.

Functionalization of halloysite nanotubes by enlargement and layer-by-layer assembly for controlled release of the fungicide iodopropynyl butylcarbamate.

Iodopropynyl butylcarbamate (IPBC) is currently one of the most important fungicides widely used for industrial coatings and bamboo treatment. In this work, a controlled release composite with IPBC for inhibition of mold and stain fungi was prepared using enlarged halloysite nanotubes (HNTs) with layer-by-layer (LbL) assembly of polyelectrolyte multilayers. The acid-treated HNTs retained their tubular structure with increased internal diameter, and IPBC loading efficiency was therefore increased to 24.4%, approximately three times the amount of raw HNTs (8.4%). In vitro drug release assay showed that IPBC could be released from HNTs in a sustainable manner with a total release amount of 33.8% over a period of 35 days. The release rate of IPBC could be further controlled by adjusting the number of LbL layers on the tubes and the released amount of IPBC could be limited to less than 10% in 100 days. An inhibition zone test indicated the as-prepared nanocomposites exhibited significant anti-fungal performance against three mold fungi (Aspergillus niger, Trichoderma viride, and Penicillium citrinum) and one stain fungus (Botryodiplodia theobromae). The results support the potential use of HNTs for a prolonged service life of bamboo products.