Clindamycin-Loaded Halloysite Nanotubes as the Antibacterial Component of Composite Hydrogel for Bone Repair.

A new drug delivery system consisting of clindamycin phosphate entrapped in acid-etched halloysite nanotubes was successfully prepared and characterized. It was then used as an antibacterial component of the multicomponent hydrogel designed as a material for bone regeneration. First, halloysite (HNT) was etched and clindamycin phosphate (CP) was entrapped in both raw and modified nanotubes, resulting in HNT-CP and EHNT-CP systems. They were characterized using SEM, TEM, TGA and FTIR; the entrapment efficiency and release of CP from both systems were also studied. EHNT-CP was then used as an antibacterial component of the two hydrogels composed of alginate, collagen and ß-TCP. The hydrogels were prepared using different crosslinking procedures but had the same composition. The morphology, porosity, degradation rate, CP release profile, cytocompatibility, antibacterial activity and ability to induce biomineralization were studied for both materials. The hydrogel obtained by a chemical crosslinking with EDC followed by the physical crosslinking with calcium ions had better properties and was shown to have potential as a bone repair material.

Application of Halloysite Nanotubes in Cancer Therapy-A Review.

Halloysite, a nanoclay characterized by a unique, tubular structure, with oppositely charged interior and exterior, suitable, nanometric-range size, high biocompatibility, and low cost, is recently gaining more and more interest as an important and versatile component of various biomaterials and delivery systems of biomedical relevance. One of the most recent, significant, and intensely studied fields in which halloysite nanotubes (HNTs) found diverse applications is cancer therapy. Even though this particular direction is mentioned in several more general reviews, it has never so far been discussed in detail. In our review, we offer an extended survey of the literature on that particular aspect of the biomedical application of HNTs. While historical perspective is also given, our paper is focused on the most recent developments in this field, including controlled delivery and release of anticancer agents and nucleic acids by HNT-based systems, targeting cancer cells using HNT as a carrier, and the capture and analysis of circulating tumor cells (CTCs) with nanostructured or magnetic HNT surfaces. The overview of the most up-to-date knowledge on the HNT interactions with cancer cells is also given.

Bioactive hydrogel scaffolds reinforced with alkaline-phosphatase containing halloysite nanotubes for bone repair applications.

Alkaline phosphatase (ALP), biomineralization promoting enzyme, was immobilized in halloysite (HAL) nanotubes and used as a bioactive component of the chitosan (CH) and chitosan-collagen (C-CH) hydrogel scaffolds for bone regeneration. The influence of HAL-ALP and collagen on the properties of the obtained materials was studied. 30 wt% of HAL-ALP increased significantly the swelling ratio of chitosan-based scaffolds. The presence of both: collagen and HAL-ALP had positive effect on the scaffolds' porosity, which was considerably higher for C-CH. The presence of HAL has improved the mechanical properties of both types of scaffolds, while the addition of 20% of collagen to the chitosan hydrogels have considerably decreased their storage modulus. Biomineralization tests showed that although mineral was formed in both CH and C-CH scaffolds with HAL-ALP, the process was more effective for collagen-containing hydrogels. Biological studies, performed using MG-63 osteoblast-like cell line showed that C-CH scaffolds, especially those after biomineralization, were a better material for cell adhesion and growth. Both types of scaffolds degraded slowly in physiological pH. C-CH scaffolds containing 30% of HAL-ALP have the highest potential as bioactive material for bone regeneration.