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

A yeast-malic acid crosslinker/polyacrylic acid hydrogel containing doxycycline for the treatment of periodontitis

Doxycycline (DX) is a drug of choice for the treatment of periodontitis, with the limitation of requiring a high dose, which may be overcome by the preparation of a targeted controlled-release hydrogel containing a newly synthesized yeast-malic acid crosslinker (YMC). YMC was synthesized via thermochemical modification of yeast with malic acid at 100-140 °C and compared with glutaraldehyde-saturated toluene (GST). Swelling capacity, acid and carboxyl content, scanning electron microscopy (SEM) imaging, Brunauer-Emmett-Teller (BET) analysis, viscosity, cross-linking density, DX loading and release behavior at pH 6.5, mucoadhesion, and antimicrobial and periodontal efficacy of the glutaraldehyde hydrogel (HGG) and YMC hydrogel (HGY) were compared. Changes from C-O (1421 cm-1) to C[double bond, length as m-dash]OOR (1702 cm-1) in the infrared spectroscopy, along with changes in the degree of substitution from 0 to 0.39, degree of esterification from 0 to 40 ± 1.5 and COOH content from 129 ± 0.5 to 290 ± 0.5 (meq. per 100 g), were found between yeast to YMC, respectively. The results revealed 1.5 times more dynamic swelling, 0.25-fold decrease in acid content, 2.3-fold increase in carboxyl content, and 1.2- and 2.1-fold increases in cross-linking density and viscosity of HGY as compared to HGG, respectively. The SEM and BET results revealed that HGY had a 2 times greater porous surface than HGG. HGY/DX was 35 ± 2% more effective in controlling periodontitis bacteria, decreased periodontal depth from 4 to 3.2 mm, and gingival index from 3 to 1 as compared to HGG/DX in patients suffering from periodontitis. HGY/DX not only serves as a tool for the controlled release of DX in periodontal pockets but also contributes to the treatment of gingival periodontitis.

Development and characterization of three-dimensional antibacterial nanocomposite sponges of chitosan, silver nanoparticles and halloysite nanotubes

In this work, we developed novel nanocomposite three-dimensional (3D) scaffolds composed of chitosan (CTS), halloysite nanotubes (HNTs) and silver nanoparticles (AgNPs) with enhanced antimicrobial activity and fibroblast cell compatibility for their potential use in wound dressing applications. A stock CTS-HNT solution was obtained by mixing water-dispersed HNTs with CTS aqueous-acid solution, and then, AgNPs, in different concentrations, were synthesized in the CTS-HNT solution via a CTS-mediated in situ reduction method. Finally, freeze-gelation was used to obtain CTS-HNT-AgNP 3D porous scaffolds (sponges). Morphology analysis showed that synthesized AgNPs were spherical with an average diameter of 11 nm. HNTs' presence did not affect the AgNPs morphology or size but improved the mechanical properties of the scaffolds, where CTS-HNT sponges exhibited a 5 times larger compression stress than bare-CTS sponges. AgNPs in the scaffolds further increased their mechanical strength in correlation to the AgNP concentration, and conferred them improved antibacterial activity against Gram-negative and Gram-positive bacteria, inhibiting the planktonic proliferation and adhesion of bacteria in a AgNP concentration depending on manner. In vitro cell viability and immunofluorescence assays exhibited that human fibroblast (HF) culture was supported by the sponges, where HF retained their phenotype upon culture on the sponges. Present CTS-HNT-AgNP sponges showed promising mechanical, antibacterial and cytocompatibility properties to be used as potential scaffolds for wound dressing applications.

The Horizons of Medical Mineralogy: Structure-Bioactivity Relationship and Biomedical Applications of Halloysite Nanoclay

Medical mineralogy explores the interactions between natural minerals and living organisms such as cells, tissues, and organs and develops therapeutic and diagnostic applications in drug delivery, medical devices, and healthcare materials. Many minerals (especially clays) have been recognized for pharmacological activities and therapeutic potential. Halloysite clay (Chinese medicine name: Chishizhi), manifested as one-dimensional aluminum silicate nanotubes (halloysite nanotubes, HNTs), has gained applications in hemostasis, wound repair, gastrointestinal diseases, tissue engineering, detection and sensing, cosmetics, and daily chemicals formulations. Various biomedical applications of HNTs are derived from hollow tubular structures, high mechanical strength, good biocompatibility, bioactivity, and unique surface characteristics. This natural nanomaterial is safe, abundantly available, and may be processed with environmentally safe green chemistry methods. This review describes the structure and physicochemical properties of HNTs relative to bioactivity. We discuss surface area, porosity and surface defects, hydrophilicity, heterogeneity and charge of external and internal surfaces, as well as biosafety. The paper provides comprehensive guidance for the development of this tubule nanoclay and its advanced biomedical applications for clinical diagnosis and therapy.

Dual-Responsive Microsphere Based on Natural Sunflower Pollen for Hemostasis and Repair in Inflammatory Bowel Disease

Noninvasive treatment of inflammatory bowel disease with lower gastrointestinal bleeding is a major clinical challenge. In this study, we designed an orally targeted microsphere based on sunflower pollen microcapsules to localize the site of inflammatory injury and promote hemostasis and tissue repair. Due to the Eudragit and ascorbate palmitate coatings, EL/AP@PS(t+Dex) demonstrates pH- and enzyme-responsive release of loaded drugs and helps to resist the harsh environment of the gastrointestinal tract. Both in vitro and in vivo experiments show the characteristics of inflammation targeting and mucosal adhesion, which reduce the systematic exposure and increase the local drug concentration. In the DSS model, orally administered EL/AP@PS(t+Dex) significantly alleviates hematochezia, inhabits intestinal inflammation, and remarkably promotes the recovery of the intestinal epithelial barrier to reduce the exposure of intestinal microvessels. Furthermore, EL/AP@PS(t+Dex) optimized the composition of intestinal microbiota, which benefits intestinal homeostasis. This finding provides a fundamental solution for the treatment of intestinal bleeding caused by inflammatory bowel disease (IBD).

Polyethylene glycol crosslinked modified chitosan/halloysite nanotube composite aerogel microspheres for efficient adsorption of melanoidin

Melanoidins are widely present in molasses wastewater and are dark-colored macromolecules that are hazardous to the environment. Currently, adsorption methods can effectively remove melanoidins from wastewater. However, existing adsorbents have shown unsatisfactory removal efficiency for melanoidins, making practical application challenging. Polyethylene glycol crosslinked modified chitosan/halloysite nanotube composite aerogel microspheres (PCAM@HNTs) were developed as a highly efficient adsorbent for melanoidins. The removal rate of PCAM@HNTs for melanoidins was 98.53 % at adsorbent dosage 0.4 mg/mL, pH 7, temperature 303 K and 450 mg/L initial melanoidins concentration, and the corresponding equilibrium adsorption capacity was 1108.49 mg/g. The analysis results indicate that the adsorption of melanoidins by PCAM@HNTs is a spontaneous and endothermic process. It fits well with pseudo-second-order kinetic models and the Freundlich isotherm equation. The adsorption of PCAM@HNT on melanoidins is primarily attributed to electrostatic and hydrogen bonding interactions. Furthermore, PCAM@HNTs exhibit excellent biocompatibility and are nonhazardous. Therefore, PCAM@HNTs proved to be an ideal adsorbent for the decolorization of molasses wastewater.

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.

Progress and future prospects of hemostatic materials based on nanostructured clay minerals

The occurrence of uncontrolled hemorrhage is a significant threat to human life and health. Although hemostatic materials have made remarkable advances in the biomaterials field, it remains a challenge to develop safe and effective hemostatic materials for global medical use. Natural clay minerals (CMs) have long been used as traditional inorganic hemostatic agents due to their good hemostatic capability, biocompatibility and easy availability. With the advancement of science, technology and ideology, CM-based hemostatic materials have undergone continuous innovations by integrating new inspirations with conventional concepts. This review systematically summarizes the hemostatic mechanisms of different natural CMs based on their nanostructures. Moreover, it also comprehensively reviews the latest research progress for CM-based hemostatic hybrid and nanocomposite materials, and discusses the challenges and developments in this field.

Chitosan-coated halloysite nanotube magnetic microspheres for carcinogenic colorectal hemorrhage and liver laceration in albino rats

Carcinogenic colorectal hemorrhage can cause severe blood loss and longitudinal ulcer, which ultimately become fatal if left untreated. The present study was aimed to formulate targeted release gemcitabine (GC)-containing magnetic microspheres (MM) of halloysite nanotubes (MHMG), chitosan (MCMG), and their combination (MHCMG). The preparation of MM by magnetism was confirmed by vibrating sample magnetometry (VSM), the molecular arrangement of NH2, alumina, and silica groups was studied by X-ray diffraction (XRD) and energy-dispersive spectroscopy (EDS), the hollow spherical nature of the proposed MM was observed by scanning electron microscopy (SEM), functional groups were characterized by Fourier transform infrared (FTIR) spectroscopy and thermochemical modification was studied by thermogravimetric analysis (TGA). In vitro thrombus formation showed a decreasing trend of hemostatic time for MMs in the order of MHMG3 < MCMG3 < MHCMG7, which was confirmed by whole blood clotting kinetics. Interestingly, rat tail amputation and liver laceration showed 3 folds increased clotting efficiency of optimized MHCMG7 compared to that of control. In vivo histopathological studies and cell viability assays confirmed the regeneration of epithelial cells. The negligible systemic toxicity of MHCMG7, more than 90% entrapment of GC and high % release in alkaline medium made the proposed MM an excellent candidate for the control of hemorrhage in colorectal cancer. Conclusively, the healing of muscularis and improved recovery of the colon from granulomas ultimately improved the therapeutic effects of GC-containing MMs. The combination of both HNT and CTS microspheres made them more targeted.

Novel chitosan/citric acid modified pistachio shell/halloysite nanotubes cross-linked by glutaraldehyde biocomposite beads applied to methylene blue removal

In this study, Cht/PS-CA/HNT biocomposite adsorbent was synthesized using halloysite nanotube as nanomaterial, chitosan which is a biodegradable and biocompatible biopolymer, pistachio shell as biomass source, citric acid as biomass modifier. The removal of methylene blue dyestuff on the synthesized new Cht/PS-CA/HNT from the aqueous medium by adsorption method was investigated. Experimental parameters such as dye concentration, contact time, amount of adsorbent, solution pH and temperature, which affect the adsorption process, were investigated. The adsorption experimental data were analyzed with the Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherms, which are widely used in aqueous solutions, and it was decided that Langmuir is the most suitable isotherm. The maximum adsorption capacity of the monolayer was calculated to be 111.14 mg/g. Optimum contact time and adsorbent dose were determined as 90 min and 1 g/L. Adsorption experimental data were applied for Pseudo-first-order and Pseudo-second-order kinetic models and it was decided that the most suitable kinetic model was pseudo-second-order. Thermodynamic evaluation of adsorption showed that adsorption is endothermic and adsorption is spontaneous.

Photothermal/lysozyme-catalyzed hydrolysis dual-modality therapy via halloysite nanotube-based platform for effective bacterial eradication

Bacterial biofilm seriously impedes the healing of infected wound, remaining a major challenge in wound repair. Antibiotic-free antibacterial strategies based on nanotechnology are emerging as promising tools to combat bacterial infections. Here, halloysite nanotube (HNT), as a natural clay mineral, was employed to fabricate a multifunctional platform (designated as HNTs@CuS@PDA-Lys) through a layer-by-layer strategy for treating bacterial infections by utilizing synergistic lysozyme (Lys)-photothermal therapy (PTT). Specifically, amino-modified HNTs were first decorated with copper sulfide (CuS), followed by coated with a polydopamine (PDA) layer, then functionalized with antimicrobial enzyme Lys onto the surface of PDA via cation-π interactions. The as-prepared HNTs@CuS@PDA-Lys at a low dose (200 μg/mL) exhibited excellent synergistic Lys-photothermal bactericidal activity against Escherichia coli (E. coli) (100.0 ± 0.2 %) and Staphyloccocus aureus (S. aureus) (99.9 ± 0.1 %), eliminated 75.9 ± 2.0 % of S. aureus biofilm under near-infrared (NIR) irradiation (808 nm, 1.5 W/cm²). In vivo experiments using a S. aureus-infected rat model showed HNTs@CuS@PDA-Lys could rapidly kill bacteria and accelerate wound healing process. Overall, this multifunctional nanoplatform combines the advantages of PTT and Lys, providing a cost-efficient, environmental friendly strategy for bacterial and biofilm eradication, demonstrating the potential applications in the field of biomedicine.

Concomitant Effect of Quercetin and Its Copper Complex in the Development of Sustained-Release Nanoparticles of Polycaprolactone, Used for the Treatment of Skin Infection

The study aimed to improve the treatment of impetigo with naturally occurring quercetin and its copper-quercetin (Cu-Q) complex by preparing sustained-release (SR) nanoparticles of polycaprolactone (PCL). The solvent evaporation method was used for the copper-quercetin (Cu-Q) complex formation, and their PCL nanoparticles (PCL-NPs, Q-PCL-NPs, and Cu-Q-PCL-NPs) were prepared by the high-pressure homogenization method. Synthesis of nanoparticles was confirmed by their physicochemical and antibacterial properties of quercetin against Gram-positive as well as Gram-negative bacteria. The percentage loading efficiency of quercetin and release in 100 mM of phosphate buffer pH 7.4 and 5.5 at 37 °C was found to be more than 90% after 24 h with the zero-order release pattern. Minimum inhibitory concentration of nanoparticles was found to increase threefold in the case of Cu-Q-PCL-NPs may be due to the synergistic antibacterial behavior. Scanning electron microscopy showed spherical nanoparticles, and surface roughness was confirmed by atomic force microscopy analysis. Fortunately, no sign of irritation on rat skin even at 3%, was seen. In vitro antioxidant assay by 2,2-diphenyl-1-picrylhydrazyl reduction was found to be ≤80 ± 0.02% which confirmed their scavenging activity. Interestingly, for the ex vivo study, the tape-stripping model was applied against Staphylococcus aureus containing rats and showed the formation of the epidermal layer within 4-5 days. Confirmation of antibacterial activity of pure quercetin, from Cu-Q complex, and their SR release from Q-PCL-NPs and Cu-Q-PCL-NPs was considered an effective tool for the treatment of skin diseases and can be used as an alternative of already resistant ciprofloxacin in impetigo.