Influence of selective acid-etching on functionality of halloysite-chitosan nanocontainers for sustained drug release

Chitosan-Clay Mineral Nanocomposites with Antibacterial Activity for Biomedical Application: Advantages and Future Perspectives

Polymers of natural origin, such as representatives of various polysaccharides (e.g., cellulose, dextran, hyaluronic acid, gellan gum, etc.), and their derivatives, have a long tradition in biomedical applications. Among them, the use of chitosan as a safe, biocompatible, and environmentally friendly heteropolysaccharide has been particularly intensively researched over the last two decades. The potential of using chitosan for medical purposes is reflected in its unique cationic nature, viscosity-increasing and gel-forming ability, non-toxicity in living cells, antimicrobial activity, mucoadhesiveness, biodegradability, as well as the possibility of chemical modification. The intuitive use of clay minerals in the treatment of superficial wounds has been known in traditional medicine for thousands of years. To improve efficacy and overcome the ubiquitous bacterial resistance, the beneficial properties of chitosan have been utilized for the preparation of chitosan-clay mineral bionanocomposites. The focus of this review is on composites containing chitosan with montmorillonite and halloysite as representatives of clay minerals. This review highlights the antibacterial efficacy of chitosan-clay mineral bionanocomposites in drug delivery and in the treatment of topical skin infections and wound healing. Finally, an overview of the preparation, characterization, and possible future perspectives related to the use of these advancing composites for biomedical applications is presented.

Cefixime loaded bare and functionalized halloysite nanocarriers and their biomedical applications

Effective drug delivery for is the foremost requirement for the complete recovery of the disease. Nanomedicine and nanoengineering has provided so many spaces and ideas for the drug delivery design, whether controlled, targeted, or sustained. Different types of nanocarriers or nanoparticles are aggressively designed for the drug delivery applications. Clay minerals are identified as a one of the potential nanocarrier for the drug delivery. Owing to their biocompatibility and very low cytotoxicity, clay minerals showing effective therapeutic applications. In the present investigation, clay mineral, i.e., Halloysite nano tubes are utilized as a nanocarrier for the delivery of antibiotic cefixime (CFX), a third-generation cephalosporin. The HNT was first functionalized with the sulfuric acid and then further treated with the 3-(aminopropyl)triethoxysilane (APTES). The drug is loaded on three different classifications of HNTs, i.e., Bare-CFX-HNT, Acid-CFX-HNT, and APTES-CFX-HNT and their comparative analysis is established. Different characterization techniques such as X-ray diffractometry (XRD), Fourier transform infra-red (FT-IR), Transmission electron microscopy TEM), Brunauer-Emmett-Teller (BET), adsorption studies, and Thermogravimetric analysis (TGA) were performed to evaluate their chemical, structural, morphological, and thermal properties. TGA confirmed the encapsulation efficiency of Bare-CFX-HNT, Acid-CFX-HNT, and APTES-CFX-HNT as 42.65, 52.19, and 53.43%, respectively. Disk diffusion and MTT assay confirmed that the drug loaded HNTs have potential antibacterial activities and less cytotoxicity. The adsorption capacity of CFX with different HNTs are evaluated and Different adsorption and kinetic models have been discussed. Drug release studies shows that APTES-CFX-HNT showing sustained release of cefixime as compared to Bare-CFX-HNT and Acid-CFX-HNT.

Augmentin loaded functionalized halloysite nanotubes: A sustainable emerging nanocarriers for biomedical applications

Clay minerals such as Halloysite nanotubes (HNTs), abundantly available green nanomaterial, exhibit a significant advantage in biomedical applications such as drug delivery, antibacterial and antimicrobials, tissue engineering or regeneration, etc. Because of the mesoporous structure and high absorbability, HNTs exhibit great potential as a nanocarrier in drug delivery applications. The sulfuric acid treatment enhances the surface area of the HNTs and thereby improves their drug-loading capacity by enlarging their lumen space/inner diameter. In the present investigation, based on the literature that supports the efficacy of drug loading after acid treatment, a dual treatment was performed to functionalize the HNTs surface. First, the HNTs were etched and functionalized using sulfuric acid. The acid-functionalized HNTs underwent another treatment using (3-aminopropyl) triethoxysilane (APTES) to better interact the drug molecules with the HNTs surfaces for efficient drug loading. Augmentin, a potential drug molecule of the penicillin group, was used for HNTs loading, and their antibacterial properties, cytotoxicity, and cumulative drug release (%) were evaluated. Different characterization techniques, such as X-ray diffractometer (XRD) and Fourier Transform Infra-Red (FT-IR), confirm the loading of Augmentin to the APTES@Acid HNTs. TEM images confirm the effective loading of the drug molecule with the HNTs. The drug encapsulation efficiency shows 40.89%, as confirmed by the Thermogravimetric Analysis (TGA). Also, the Augmentin-loaded APTES@Acid HNTs exhibited good antibacterial properties against E. coli and S. aureus and low cytotoxicity, as confirmed by the MTT assay. The drug release studies confirmed the sustainable release of Augmentin from the APTES@Acid HNTs. Hence, the treated HNTs can be considered as a potential nanocarrier for effectively delivering Augmentin and promoting enhanced therapeutic benefits.

Recent Advances of Halloysite Nanotubes in Biomedical Applications

Halloysite nanotubes (HNTs) have emerged as a highly regarded choice in biomedical research due to their exceptional attributes, including superior loading capacity, customizable surface characteristics, and excellent biocompatibility. HNTs feature tubular structures comprising alumina and silica layers, endowing them with a large surface area and versatile surface chemistries that facilitate selective modifications. Moreover, their substantial pore volume and wide range of pore sizes enable efficient entrapment of diverse functional molecules. This comprehensive review highlights the broad biomedical application spectrum of HNTs, shedding light on their potential as innovative and effective therapeutic agents across various diseases. It emphasizes the necessity of optimizing drug delivery techniques, developing targeted delivery systems, rigorously evaluating biocompatibility and safety through preclinical and clinical investigations, exploring combination therapies, and advancing scientific understanding. With further advancements, HNTs hold the promise to revolutionize the pharmaceutical industry, opening new avenues for the development of transformative treatments.

Functionalized Halloysite Nanotubes as Potential Drug Carriers

The aim of the work was to examine the possibility of using modified halloysite nanotubes as a gentamicin carrier and to determine the usefulness of the modification in terms of the effect on the amount of the drug attached, its release time, but also on the biocidal properties of the carriers. In order to fully examine the halloysite in terms of the possibility of gentamicin incorporating, a number of modifications of the native halloysite were carried out prior to gentamicin intercalation with the use of sodium alkali, sulfuric and phosphoric acids, curcumin and the process of delamination of nanotubes (expanded halloysite) with ammonium persulfate in sulfuric acid. Gentamicin was added to unmodified and modified halloysite in an amount corresponding to the cation exchange capacity of pure halloysite from the Polish Dunino deposit, which was the reference sample for all modified carriers. The obtained materials were tested to determine the effect of surface modification and their interaction with the introduced antibiotic on the biological activity of the carrier, kinetics of drug release, as well as on the antibacterial activity against Escherichia coli Gram-negative bacteria (reference strain). For all materials, structural changes were examined using infrared spectroscopy (FTIR) and X-ray diffraction (XRD); thermal differential scanning calorimetry with thermogravimetric analysis (DSC/TG) was performed as well. The samples were also observed for morphological changes after modification and drug activation by transmission electron microscopy (TEM). The conducted tests clearly show that all samples of halloysite intercalated with gentamicin showed high antibacterial activity, with the highest antibacterial activity for the sample modified with sodium hydroxide and intercalated with the drug. It was found that the type of halloysite surface modification has a significant effect on the amount of gentamicin intercalated and then released into the surrounding environment but does not significantly affect its ability to further influence drug release over time. The highest amount of drug released among all intercalated samples was recorded for halloysite modified with ammonium persulfate (real loading efficiency above 11%), for which high antibacterial activity was found after surface modification, before drug intercalation. It is also worth noting that intrinsic antibacterial activity was found for non-drug-intercalated materials after surface functionalization with phosphoric acid (V) and ammonium persulfate in the presence of sulfuric acid (V).

Functionally modified halloysite nanotubes for personalized bioapplications

Halloysite nanotubes (HNTs) are naturally aluminosilicate clay minerals that have the benefits of large surface areas, high mechanical properties, easy functionalization, and high biocompatibility, HNTs have been developed as multifunctional nanoplatforms for various bioapplications. Although some reviews have summarized the properties and bioapplications of HNTs, it remains unclear how to functionalize the modifications of HNTs for their personalized bioapplications. In this review, based on the physicochemical properties of HNTs, we summarized the methods of functionalized modifications (surface modification and structure modification) on HNTs. Also, we highlighted their personalized bioapplications (anti-bacterial, anti-inflammatory, wound healing, cancer theranostics, bone regenerative, and biosensing) by stressing on the main roles of HNTs. Finally, we provide perspectives on the future of functionalized modifications of HNTs for docking specific biological applications.

Investigation on the Potential Application of Na-Attapulgite as an Excipient in Domperidone Sustained-Release Tablets

In this study, Na-attapulgite was explored as an excipient to prepare domperidone sustained-release tablets and test them in accordance with United States Pharmacopoeia requirements. Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD) and differential scanning calorimetry (DSC) were employed to explore the compatibility between Na-attapulgite and domperidone. The XRD and DSC show no interaction between the drug and Na-attapulgite. The FTIR spectrum indicates a shift in the absorption of N-H in the drug molecule, which can be explained by the hydrogen bonding interaction between the N-H in the DOM molecule and the -OH on the surface of Na-ATP. The diameter, hardness, friability and drug content of the tablets were measured, and they all met the relevant requirements of the United States Pharmacopoeia. In addition, the tablets with Na-attapulgite as excipient exhibit a better release performance within the release time of 12 h. These results demonstrate that the domperidone sustained-release tablets have been successfully prepared by using Na-attapulgite as an excipient. The doping of Na-ATP in domperidone sustained-release tablets improves the cytocompatibility. Moreover, with the increase of Na-ATP content, cells proliferate remarkably and cell activity is significantly enhanced.

Fabrication of a magnetic alginate-silk fibroin hydrogel, containing halloysite nanotubes as a novel nanocomposite for biological and hyperthermia applications

In this study, the main focus was on designing and synthesizing a novel magnetic nanobiocomposite and its application in hyperthermia cancer treatment. Regarding this aim, sodium alginate (SA) hydrogel with CaCl₂ cross-linker formed and modified by silk fibroin (SF) natural polymer and halloysite nanotubes (HNTs), followed by in situ Fe₃O₄ magnetic nanoparticles preparation. No important differences were detected in red blood cells (RBCs) hemolysis, confirming the high blood compatibility of the treated erythrocytes with this nanobiocomposite. Moreover, the synthesized SA hydrogel/SF/HNTs/Fe₃O₄ nanobiocomposite does not demonstrate toxicity toward HEK293T normal cell line after 48 and 72 h. The anticancer property of SA hydrogel/SF/HNTs/Fe₃O₄ nanobiocomposites against breast cancer cell lines was corroborated. The magnetic saturation of the mentioned magnetic nanobiocomposite was 15.96 emu g⁻¹. The specific absorption rate (SAR) was measured to be 22.3 W g⁻¹ by applying an alternating magnetic field (AMF). This novel nanobiocomposite could perform efficiently in the magnetic fluid hyperthermia process, according to the obtained results.

Nanocomposite Film Development Based on Chitosan/Polyvinyl Alcohol Using ZnO@montmorillonite and ZnO@Halloysite Hybrid Nanostructures for Active Food Packaging Applications

The global turn from the linear to the circular economy imposes changes in common activities such as food packaging. The use of biodegradable materials such as polyvinyl alcohol, natural raw materials such as clays, and food byproducts such as chitosan to develop novel food packaging films attracts the interest of industrial and institutional research centers. In this study, novel hybrid nanostructures were synthesized via the growth of zinc oxide nanorods on the surface of two nanoclays. The obtained nanostructures were incorporated with chitosan/polyvinyl alcohol composite either as nanoreinforcement or as an active agent to develop packaging films. The developed films were characterized via XRD, FTIR, mechanical, water-vapor diffusion, water sorption, and oxygen permeability measurements. Antimicrobial activity measurements were carried out against four different pathogen microorganisms. XRD indicated the formation of an intercalated nanocomposite structure for both types of nanoclays. Furthermore, improved tensile, water/oxygen barrier, and antimicrobial properties were recorded for all films compared to the pure chitosan/polyvinyl alcohol film. Overall, the results indicated that the use of the bio-based developed films led to an extension of food shelf life and could be used as novel active food packaging materials. Among them, the most promising film was the 6% wt. ZnO@halloysite.

Chitosan/halloysite nanotubes microcomposites: A double header approach for sustained release of ciprofloxacin and its hemostatic effects

Clotting time of lower gastro intestinal bleeding (LGIB) can be reduced by using simple, cost-effective, and naturally occurring halloysite nanotubes (HNTs). The present study aimed to decrease the clotting time by the application of chitosan (CHT) and its microcomposites (MCs) prepared by suspension emulsification technique with HNTs (CHT/HNTs MC). Physicochemical properties, X-Ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and percentage release of ciprofloxacin from CHT/HNTs MCs was evaluated. In-vitro procoagulant activity of CHT, HNTs and their complexes CHT/HNTs MCs was performed on rabbit blood which was confirmed by a rat tail amputation. Direct relation of HNTs was observed for the whole-blood clotting kinetics i.e., 2% HNTs showed a maximum 66.0% increase in the clotting ability as compared with pure CHT. Interestingly, rat-tail amputation studies showed comparative results of CHT, HNTs, and CHT/HNTs MCs. A total of 75% permeation of ciprofloxacin of CHT/HNTs MCs on rat intestinal membrane was observed within 3 h, confirming their SR behavior. Furthermore, improved hemostatic and clotting properties were CHT/HNTs MC₁ > CHT/HNTs MC₂ > CHT/HNTs MC₃ > CHT > HNTs, respectively. Thus, it provided the control of bleeding disorders in LGIB with any antibacterial agents, particularly ciprofloxacin.