The development and application of nanocomposites with pH-sensitive “gates” to control the release of active agents: Extending the shelf-life of fresh wheat noodles

Antimicrobial film based on poly(lactic acid) and natural halloysite nanotubes for controlled cinnamaldehyde release

There is a need for titanium (Ti), an antimicrobial implant coating that provides sustained protection against bacterial infection. Chitosan (CS) coatings, combined with halloysite nanotubes (HNTs), are an attractive solution due to the inherent biocompatibility of halloysite, its ability to provide sustained drug release, and the antimicrobial properties of CS. In this study, the electrodeposition (EPD) method was used to coat titanium foil with CS blended with zinc-coated HNTs (ZnHNTs) and pre-loaded with the antibiotic gentamicin. The CS-ZnHNTs-gentamycin sulfate (GS) coatings were characterized using scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray powder diffraction (XRD), X-ray fluorescence (XRF), Fourier-transform infrared spectroscopy (FTIR), and UV-visible spectroscopy. The coatings were further examined for their ability to sustain GS release, resist bacterial colonization and growth, and prevent biofilm formation. The CS-ZnHNTs-GS coatings were cytocompatible, exhibited significant antimicrobial properties, and supported pre-osteoblast cell proliferation. Hydroxyapatite also formed on the coatings after immersion in simulated body fluid. While the focus in this study was on zinc-coated HNTs doped into CS, our design offers tunability, as different metals can be coated onto the HNT surface and different drugs or growth factors loaded into the HNT lumen. Our results, and the potential for customization, suggest that these coatings have potential in the construction of an array of infection-resistant implant coatings.

The worsening environment and the demand for safer food have accelerated the development of new food packaging materials. The objective of this research is to prepare antimicrobial food packaging film with controlled release by loading cinnamaldehyde (CIN) on etched halloysite nanotubes (T-HNTs) and adding it to sodium alginate (SA) matrix. The effects of T-HNTs-CIN on the physical functional properties and antibacterial activity of the film were systematically evaluated, and the release of CIN in the film was also quantified. Transmission electron microscopy and nitrogen adsorption experiments showed that the halloysite nanotubes had been etched and CIN was successfully loaded into the T-HNTs. The addition of T-HNTs-CIN significantly improved the water vapor barrier properties and tensile strength of the film. Similarly, the presence of T-HNTs-CIN in the film greatly reduced the negative effects of ultraviolet rays. The release experiment showed that the diffusion time of CIN in SA/T-HNTs-CIN film to fatty food simulation solution was delayed 144 h compared with that of SA/CIN film. Herein, the antibacterial experiment also confirmed the controlled release effect of T-HNTs on CIN. In conclusion, SA/T-HNTs-CIN film might have broad application prospects in fatty food packaging.

The use of nanomaterials for improving drug delivery methods has been shown to be advantageous technically and viable economically. This study employed the use of halloysite nanotubes (HNTs) as nanocontainers, as well as enhancers of structural integrity in electrospun poly-e-caprolactone (PCL) scaffolds. HNTs were loaded with amoxicillin, Brilliant Green, chlorhexidine, doxycycline, gentamicin sulfate, iodine, and potassium calvulanate and release profiles assessed. Selected doped halloysite nanotubes (containing either Brilliant Green, amoxicillin and potassium calvulanate) were then mixed with poly-e-caprolactone (PLC) using the electrospinning method and woven into random and oriented-fibered nanocomposite mats. The rate of drug release from HNTs, HNTs/PCL nanocomposites, and their effect on inhibiting bacterial growth was investigated. Release profiles from nanocomposite mats showed a pattern of sustained release for all bacterial agents. Nanocomposites were able to inhibit bacterial growth for up to one-month with only a slight decrease in bacterial growth inhibition. We propose that halloysite doped nanotubes have the potential for use in a variety of medical applications including sutures and surgical dressings, without compromising material properties.

BackgroundRemovable dentures are one of the common treatment modalities used to restore missing teeth. Denture stomatitis, caused by the adhesion of Candida albicans, is considered a major complication of these prostheses. The purpose of this article is to evaluate the impact of adding Halloysite Nanotubes (HNTs) on the surface roughness (Ra, µm), color change (∆E*), and Candida albicans adhesion in 3D-printed denture base resins (PDBRs).MethodsThree concentrations (0.3%,0,6%, and 0.9%wt.) of HNTs were added to two PDBRs, ASIGA and NextDent, while the control group remained without HNTs addition. The specimens were printed in a disk shape (15 × 2 mm). After printing, specimens were thermocycled (5000 cycles). Surface roughness was measured using a non-contact profilometer. Color change (∆E*) was measured using the Commission International de l’Eclairage (CIE) system coordinates (L*, a*, b*) method. C. albicans adhesion was evaluated using a colony-forming unit (CFU/mL). The collected data were statistically analyzed using ANOVA and a post-hoc Tukey test (α = 0.05).ResultsThe addition of HNTs showed no significant difference in surface roughness between all tested groups (P ˃0.05). Adding HNTs resulted in a slight color change at 0.3% and 0.6%, while 0.9% significantly increased the color change (P < 0.001) with a noticeable difference. Adding HNTs significantly decreased the C. albicans adhesion to PDBRs compared to pure resins (P < 0.001). Regarding the concentration effect, the effect was concentration-dependent, with 0.9% showing the lowest Candida colony count for ASIGA resin (1018.9 ± 80.0) and NextDent resins (911.1 ± 89.3).ConclusionAdding HNTs to PDBRs did not change the surface roughness and significantly decreased C. albicans adhesion. The color was changed with HNTs to noticeable with 0.9%HNTs. Due to the antifungal activities of PDBRs containing HNTs, these PDBRs could be recommended as a method for preventing denture stomatitis.

Trapping characteristic of halloysite lumen for methyl orange

Increasing health concerns regarding the use of plasticware have led to the development of ecofriendly biodegradable packaging film from natural polymer and food additives. In the present study, basil essential oil (BEO) loaded halloysite nanotubes (HNTs) composite films were synthesized using a solution casting method. The effects of BEO and nanotube concentration on the mechanical, physical, structural, barrier, and antioxidant properties of films were evaluated. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) demonstrated well-dispersed HNTs and BEO in tailored composite films. The addition of BEO in Chitosan (Ch) film caused darkening of the film color; furthermore, the incorporation of HNTs in varied concentrations increased opaqueness in Ch/BEO film. The Ch/BEO film, upon adding HNTs 5-30 wt%, exhibited a corresponding increase in the film thickness (0.108-0.135 mm) when compared with the Ch/BEO film alone (0.081 mm). The BEO-loaded HNTs composite films displayed reduced moisture content and characteristic barrier and UV properties. The Ch/BEO film with 15 wt% HNTs was found to have enhanced antioxidant activity. The Ch/BEO/HNTs composite also managed to prevent broccoli florets from losing weight and firmness during storage. The enhanced barrier and antioxidant qualities of the nanocomposite film suggest its potential application in the food processing and packaging sector. This is the first ever report on the fabrication of nanocomposite film using BEO and HNTs for food packaging. The low production cost and ecofriendly approach make the film acceptable for further research and commercialization thereafter.

Effects of pure and intercalated halloysites on thermal properties of phthalonitrile resin nanocomposites

To solve the problems of low flame retardant efficiency and weak low-temperature performance of asphalt modified by conventional flame retardants (CFR), in this study, halloysite nanotubes (HNTs) and CFR were used to prepare nanocomposite flame retardants (NCFR) to modify asphalt. A fluorescence microscope (FM), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscope/energy dispersive spectrometer (SEM/EDS) were used to characterize the microstructure of NCFR-modified asphalt. An oxygen index meter, Cleveland open cup, and cone calorimeter were used to test the flame retardant properties of the asphalt. A dynamic shear rheometer, bending beam rheometer, and force ductility tester were used to test the rheological properties of asphalt. At the same time, flame retardant–modified asphalt mixtures were prepared to verify the flame retardancy and road performance of the flame retardant–modified asphalt. The research results showed that the asphalt modified with 8% CFR and 1% HNTs (MA/CFR/1% HNTs) showed better dispersibility. The increase of limiting oxygen index and self-ignition temperature and the decrease of heat release rate and smoke production rate of MA/CFR/1% HNTs indicated that it has good flame retardancy. At 64°C, compared with modified asphalt (MA), the rutting factor of MA/CFR/1% HNTs increased by 88.17%, the creep recovery increased, and the irreversible creep decreased, indicating that its high-temperature performance improved significantly. At −18°C, compared with that of MA/CFR, the low-temperature creep stiffness of MA/CFR/1% HNTs decreased by 36 MPa and the creep rate of MA/CFR/1% HNTs increased by 0.034, indicating that only 1% HNTs can improve the effect of degraded CFR on the low-temperature performance of MA. Simultaneously, MA/CFR and MA/CFR/1% HNTs can improve the high-temperature performance and water stability of asphalt mixtures. Adding 1% HNTs to a MA/CFR-modified asphalt mixture can improve the low-temperature performance of the asphalt mixture to the level of the low-temperature performance of the modified asphalt mixture. In summary, the modification of asphalt with 1% HNTs and 8% CFR can effectively improve the flame retardant efficiency and significantly improve the road performance of asphalt.

Amine-based adsorbents are considered extremely promisingcandidatesfor their efficacy in CO2 capture. In this study, we explorethe enhancement of CO2 adsorption capacity through thedevelopment of a hierarchically porous material containing a mesoporoussilica coating on halloysite nanotubes (HNTs), a naturally occurringclay material. The generation of a mesoporous MCM-41 skin on HNTsincreases the surface area from about 60 to 400 m2/g whilemaintaining structural integrity. This significant increase in thesurface area helps enhance amine loading. The synthesis of the MCM-41/HNT(MHNT) composite particles was achieved via an aerosol-assisted method,allowing rapid coating formation of a spindle-shaped skin on the HNTexternal surface and leading to a hierarchical porosity that supportsboth large pores in the HNT lumen and small pores in the MCM-41 coating.Poly­(ethylenimine) (PEI)-loaded MHNT adsorbents exhibit superior CO2 adsorption capacities compared to adsorbents of PEI loadedinto pristine HNT, with a 27% increase in the adsorption capacity.This work underscores the effectiveness of mesoporous skin in increasingamine adsorption efficiency on clay-based adsorbents, providing apathway for the development of high-capacity, durable materials incarbon capture technologies.

An easy strategy to obtain inorganic reverse micelles based on halloysite nanotubes (HNTs) and alkyltrimethylammonium bromides has been developed. The selective modification of the HNTs external surface with cationic surfactants endows to generate tubular nanostructures with a hydrophobic shell and a hydrophilic cavity. The influence of the surfactants alkyl chain on the HNTs functionalization degree has been investigated. The dynamic behavior of the surfactant/HNT hybrids in solvents with variable polarity has been correlated to their affinity toward hydrophobic media explored through partition experiments. The water-in-oil emulsion is able to solubilize copper sulfate, proving the incorporation and the loading of hydrophilic compounds into the HNTs lumen. Here we have fabricated ecocompatible reverse micelles with tunable hydrophobic/hydrophilic interface that might be suitable for industrial and biological applications as well as for selective organic synthesis.

Molecules confined within nanometer‐scale environments frequently exhibit a distinct physical response in contrast to those found in bulk conditions. In this study, intercalates of lauric acid (LA) are synthesized within halloysite nanotubes (HNT), successfully trapping 12 wt.% of LA within the internal HNT tube, as demonstrated by transmission electron microscopy (TEM), and wide‐angle and small‐angle X‐ray scattering (WAXS/SAXS) techniques. Furthermore, it is noted that the confinement of LA within the HNT lumen resulted in a significant reduction in LA crystallinity, consistent with the impact of geometric constraints on crystallization behavior. The presence of a significant amorphous phase in the intercalates proved beneficial for the gradual release of LA into water, as evidenced by pH changes. Remarkably, the necessity of employing a vacuum method and extended contact time (72 h) for the physical entrapment of LA in ethanol within the HNT lumen is found to be unnecessary, as similar physical characteristics are observed in an intercalate generated without vacuum and with very short contact time (&lt;1 h). Finally, it is observed that the source of HNT is crucial in determining the final properties of the confined material.

Background/Objectives: The development of therapies targeting unregulated Src signaling through selective kinase inhibition using small-molecule inhibitors presents a significant challenge for the scientific community. Among these inhibitors, pyrazolo[3,4-d]pyrimidine heterocycles have emerged as potent agents; however, their clinical application is hindered by low solubility in water. To overcome this limitation, some carrier systems, such as halloysite nanotubes (HNTs), can be used. Methods: Herein, we report the development of HNT-based nanomaterials as carriers for pyrazolo[3,4-d]pyrimidine molecules. To achieve this objective, the clay was modified by two different approaches: supramolecular loading into the HNT lumen and covalent grafting onto the HNT external surface. The resulting nanomaterials were extensively characterized, and their morphology was imaged by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). In addition, the kinetic release of the molecules supramolecularly loaded into the HNTs was also evaluated. QSAR studies were conducted to elucidate the physicochemical and pharmacokinetic properties of these inhibitors, and structure-based virtual screening (SBVS) was performed to analyze their binding poses in protein kinases implicated in cancer. Results: The characterization methods demonstrate successful encapsulation of the drugs and the release properties under physiological conditions. Furthermore, QSAR studies and SBVS provide valuable insights into the physicochemical, pharmacokinetic, and binding properties of these inhibitors, reinforcing their potential efficacy. Conclusions: The cytotoxicity of these halloysite-based nanomaterials, and of pure molecules for comparison, was tested on RT112, UMUC3, and PC3 cancer cell lines, demonstrating their potential as effective agents for prostate and bladder cancer treatment.

Selective fabrication of iron oxide particles in halloysite lumen

High modulus and thermal stability of polyimide (PI)/reactive halloysite nanotubes (HNTs) nanocomposites were prepared by in situ polymerization. The pristine HNTs were firstly handled with the tetraethoxysilane (TEOS) and secondly grafted with the silane agent. The fourier transform infrared spectroscopy (FTIR) approved that TEOS was beneficial for the silane agent to modify the HNTs. Scanning electron microscopy (SEM) showed the differences of the morphology between the reactive HNTs and pristine HNTs. PI/reactive HNTs nanocomposites exhibited lower moisture absorption than pure polyimide. The reactive HNTs reduced the transmittance of the nanocomposites. Significant improvements in the thermal stability and glass transition temperature (Tg) of PI/reactive HNTs nanocomposites were achieved by addition of only a small amount of reactive HNTs. It was noteworthy that both the tensile strength and Young' modulus of PI/reactive HNTs nanocomposites were significantly enhanced. A 62.8 % increase in tensile strength and a 63.7 % increase in Young' modulus of the nanocomposites with 3 wt.% of the reactive HNTs were achieved. Finally, the preparation mechanism to obtain PI/reactive HNTs nanocomposites was proposed.