Special Issue "Surface Modification of Halloysite Nanotubes"

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Nanotechnology and Applied Nanosciences".

Deadline for manuscript submissions: closed (30 September 2017)

Special Issue Editor

Guest Editor
Prof. Dr. David K. Mills

Biomedical Engineering/ Biological Sciences, Louisiana Tech University, Ruston, LA. 71272, United States
Website | E-Mail
Interests: cancer biomaterials; bioengineering, implant design, surface modification; targeted drug delivery; tissue engineering; 3D printing

Special Issue Information

Dear Colleagues,

This Special Issue highlights the current state and future prospects of a biocompatible, green, inexpensive and multifunctional clay nanoparticle. Halloysite nanotubes (HNTs) have shown to be an ideal nanoparticle for polymer reinforcement, sustained-release drug delivery, nanoreactor synthesis, and use as substrate material for nanostructured coatings. A number of methods exist on surface modification of HNTs with polyelectrolytes, polysaccharides, polymers, metals and resins. The current state-of-the-art shows a collection of technologies that use simple or multi-step chemical reactions to modify the HNT surface. Functionalized HNTs can then be applied directly for, or combined with, polymers to produce nanocomposites for use in a diverse array of biomedical applications including antimicrobial, drug delivery, regenerative medicine or tissue repair. Contributions will focus on techniques that impart specific functionalities to HNT nanotubes (HNTs) that may include increased surface area for cell penetration; drug delivery, alteration of surface pH, polymer integration, and slow release mechanisms among others.

Prof. Dr. David K. Mills
Guest Editor

Manuscript Submission Information

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Keywords

  • Drug release;
  • Halloysite nanotubes;
  • Functionalization;
  • Polyelectrolyte;
  • Polymer, surface modification

Published Papers (5 papers)

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Research

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Open AccessFeature PaperArticle Bi-Functionalized Clay Nanotubes for Anti-Cancer Therapy
Appl. Sci. 2018, 8(2), 281; https://doi.org/10.3390/app8020281
Received: 7 December 2017 / Revised: 1 February 2018 / Accepted: 8 February 2018 / Published: 13 February 2018
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Abstract
Systemic toxicity is an undesired consequence of the majority of chemotherapeutic drugs. Multifunctional nanoparticles with combined diagnostic and therapeutic functions show great promise towards personalized nanomedicine. Halloysite clay nanotubes (HNTs) have shown potential as a drug delivery vehicle, and its surface can be
[...] Read more.
Systemic toxicity is an undesired consequence of the majority of chemotherapeutic drugs. Multifunctional nanoparticles with combined diagnostic and therapeutic functions show great promise towards personalized nanomedicine. Halloysite clay nanotubes (HNTs) have shown potential as a drug delivery vehicle, and its surface can be modified and tailored as a targeted drug delivery system. In this short report, we modified the HNT surface by covalently bonding folic acid (FA) and fluorescein isothiocyanate (FITC). The modification of HNTs with folic acid imparts the potential to target tumor cells selectively. The addition of FITC offers a method for quantifying the effectiveness of the FA tagged HNTs ability to target tumor cells. We documented cell uptake of our bi-functionalized HNT (bHNT) through phase contrast and epi-fluorescent microscopy. bHNTs showed no signs of cytotoxicity up to a concentration of 150 µg/mL. The increase in cell death with increased bHNT concentration may be due to induced cytotoxicity resulting from intracellular bHNT accumulation that disrupts cellular function leading to cell death. With HNTs recognized as having the ability to serve as both a nanocontainer and nanocarrier, we envision our construct as a potential modular platform for potential use in cancer therapeutics. The HNT interior can be loaded with a variety of anti-cancer drugs (or other chemotherapeutics) and serve as a “death cargo” designed to kill cancer cells while providing feedback imaging data on drug efficacy. The surface of the HNT can be modified with gold or silver nanoparticles and used in photothermal therapy by converting light to heat inside tumors. Our HNT-based drug delivery system has the potential to provide localized and targeted therapies that limit or reduce side effects, reduce patient costs and length of hospital stays, and improve quality of life. However, further research is needed to validate the potential of this new chemotherapeutic drug delivery system. Full article
(This article belongs to the Special Issue Surface Modification of Halloysite Nanotubes)
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Open AccessArticle Preparation of Robust Superhydrophobic Halloysite Clay Nanotubes via Mussel-Inspired Surface Modification
Appl. Sci. 2017, 7(11), 1129; https://doi.org/10.3390/app7111129
Received: 20 September 2017 / Accepted: 25 October 2017 / Published: 2 November 2017
Cited by 1 | PDF Full-text (6236 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
In this study, a novel and convenient bio-inspired modification strategy was used to create stable superhydrophobic structures on halloysite clay nanotubes (HNTs) surfaces. The polydopamine (PDA) nanoparticles can firmly adhere on HNTs surfaces in a mail environment of pH 8.5 via the oxidative
[...] Read more.
In this study, a novel and convenient bio-inspired modification strategy was used to create stable superhydrophobic structures on halloysite clay nanotubes (HNTs) surfaces. The polydopamine (PDA) nanoparticles can firmly adhere on HNTs surfaces in a mail environment of pH 8.5 via the oxidative self-polymerization of dopamine and synthesize a rough nano-layer assisted with vitamin M, which provides a catechol functional platform for the secondary reaction to graft hydrophobic long-chain alkylamine for preparation of hierarchical micro/nano structures with superhydrophobic properties. The micromorphology, crystal structure, and surface chemical composition of the resultant superhydrophobic HNTs were characterized by field emission scanning electron (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The as-formed surfaces exhibited outstanding superhydrophobicity with a water contact angle (CA) of 156.3 ± 2.3°, while having little effect on the crystal structures of HNTs. Meanwhile, the resultant HNTs also showed robust stability that can conquer various harsh conditions including strong acidic/alkaline solutions, organic solvents, water boiling, ultrasonic cleaning, and outdoor solar radiation. In addition, the novel HNTs exhibited excellent packaged capabilities of phase change materials (PCMs) for practical application in thermal energy storage, which improved the mass fractions by 22.94% for stearic acid and showed good recyclability. These HNTs also exhibited good oil/water separation ability. Consequently, due to the superior merits of high efficiency, easy operation, and non-toxicity, this bionic surface modification approach may make HNTs have great potentials for extensive applications. Full article
(This article belongs to the Special Issue Surface Modification of Halloysite Nanotubes)
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Open AccessArticle Improvement of Interfacial Adhesion of Incorporated Halloysite-Nanotubes in Fiber-Reinforced Epoxy-Based Composites
Appl. Sci. 2017, 7(5), 441; https://doi.org/10.3390/app7050441
Received: 20 February 2017 / Revised: 10 April 2017 / Accepted: 22 April 2017 / Published: 27 April 2017
Cited by 4 | PDF Full-text (3589 KB) | HTML Full-text | XML Full-text
Abstract
The heart of composite materials depends on the characteristics of their interface. The physical properties of composite materials are often described by the rule of mixtures, representing the average physical properties of the reinforcement and the matrix resin. However, in practical applications there
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The heart of composite materials depends on the characteristics of their interface. The physical properties of composite materials are often described by the rule of mixtures, representing the average physical properties of the reinforcement and the matrix resin. However, in practical applications there are situations which arise where the rule of mixtures is not followed. This is because when an external energy applied to the composite material is transferred from the matrix to the reinforcement, the final physical properties are affected by the interface between them rather than the intrinsic properties of both the reinforcement and the matrix. The internal bonding strength of the interface of these composites can be enhanced by enhancing the bonding strength by adding a small amount of material at the interface. In this study, the mechanical properties were evaluated by producing a carbon fiber-reinforced composite material and improved by dispersing halloysite nanotubes (HNTs) and the epoxy resin using an ultrasonic homogenizer. The interfacial bond strength increased with the addition of HNT. On the other hand, the addition of HNTs more than 3 wt % did not show the reinforcing effect by HNT agglomeration. Full article
(This article belongs to the Special Issue Surface Modification of Halloysite Nanotubes)
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Open AccessArticle Surface Improvement of Halloysite Nanotubes
Appl. Sci. 2017, 7(3), 291; https://doi.org/10.3390/app7030291
Received: 30 December 2016 / Revised: 14 February 2017 / Accepted: 24 February 2017 / Published: 16 March 2017
Cited by 5 | PDF Full-text (1256 KB) | HTML Full-text | XML Full-text
Abstract
A novel development on halloysite-polyvinyl alcohol (HNTs-PVA) nanocomposites has been conducted using malonic acid (MA) by crosslinking PVA and HNTs. PVA-MA crosslinking produces smooth surfaces, which play an important role in enhancing the properties of HNTs-PVA nanocomposite. The crystallographic structures of crosslinked HNTs-PVA
[...] Read more.
A novel development on halloysite-polyvinyl alcohol (HNTs-PVA) nanocomposites has been conducted using malonic acid (MA) by crosslinking PVA and HNTs. PVA-MA crosslinking produces smooth surfaces, which play an important role in enhancing the properties of HNTs-PVA nanocomposite. The crystallographic structures of crosslinked HNTs-PVA show almost no change as depicted by the X-ray diffraction (XRD)-2θ-peak, suggesting that MA has no or little influence on the crystallographic structure of the HNTs-PVA. Images taken by field emission scanning electron microscope (FESEM) suggest possible effects of MA on the morphology and internal features of HNTs-PVA by reducing the agglomeration of HNTs, which is considered a decisive step in improving the surface qualities of HNTs. Investigating the samples using the Brunauer–Emmelt–Teller (BET) technique showed that the surface area was increased by about 10 times, reaching the second highest recorded results compared to the HNTs, which could be considered a breakthrough step in enhancing the properties of HNTs-PVA due to MA crosslinking. Full article
(This article belongs to the Special Issue Surface Modification of Halloysite Nanotubes)
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Review

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Open AccessReview Recent Advances on Surface Modification of Halloysite Nanotubes for Multifunctional Applications
Appl. Sci. 2017, 7(12), 1215; https://doi.org/10.3390/app7121215
Received: 30 September 2017 / Accepted: 21 November 2017 / Published: 24 November 2017
Cited by 3 | PDF Full-text (535 KB) | HTML Full-text | XML Full-text
Abstract
Halloysite nanotubes (HNTs) are natural occurring mineral clay nanotubes that have excellent application potential in different fields. However, HNTs are heterogeneous in size, surface charge, and formation of surfacial hydrogen bond, which lead to weak affinity and aggregation at a certain extent. It
[...] Read more.
Halloysite nanotubes (HNTs) are natural occurring mineral clay nanotubes that have excellent application potential in different fields. However, HNTs are heterogeneous in size, surface charge, and formation of surfacial hydrogen bond, which lead to weak affinity and aggregation at a certain extent. It is very important to modify the HNTs’ surface to expand its applications. In this review, the structural characteristics, performance, and the related applications of surface-modified HNTs are reviewed. We focus on the surface-modified variation of HNTs, the effects of surface modification on the materials and related applications in various regions. In addition, future prospects and the meaning of surface modification were also discussed in HNTs studies. This review provides a reference for the application of HNTs modifications in the field of new nanomaterials. Full article
(This article belongs to the Special Issue Surface Modification of Halloysite Nanotubes)
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