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.

Halloysite nanotubes-cellulose ether based biocomposite matrix, a potential sustained release system for BCS class I drug verapamil hydrochloride: Compression characterization, in-vitro release kinetics, and in-vivo mechanistic physiologically based pharmacokinetic modeling studies.

This study investigated the ability of natural nanotubular clay mineral (Halloysite) and cellulose ether based biocomposite matrix as a controlled release agent for Verapamil HCl (BCS Class-I). Drug-loaded halloysite was prepared and tablet formulations were designed by varying amount of hydroxy propyl methyl cellulose (HPMC K4M). Physical characterization was carried out using SEM, FTIR, and DSC. Tabletability profiles were evaluated using USP1062 guidelines. Drug release kinetics were studied, and physiologically based pharmacokinetic (PBPK) modeling was performed. Compressed tablets possess satisfactory yield pressure of 625 MPa with adequate hardness and disintegration within 30 min. The initial release of the drug was due to surface drug on tablets, while the prolonged release at later time points (around 80 % drug release at 12 h) were due to halloysite loading. The FTIR spectra exhibited electrostatic attraction between the positively charged drug and the negatively charged Si-O-Si functional group of halloysite, while the thermogram showed Verapamil HCl melting point at ~146 °C with enthalpy change of -126.82 J/g. PBPK modeling exhibited PK parameters of optimized matrix formulation (VER-HNT3%) comparable to in vivo data. The study effectively demonstrated the potential of prepared biocomposite matrix as a commercially viable oral release modifying agent for highly soluble drugs.

The Fabrication of a La2Sn2O7/f-HNT Composite for Non-Enzymatic Electrochemical Detection of 3-Nitro-l-tyrosine in Biological Samples.

Reactive oxygen and nitrogen species (RONS), including 3-nitro-l-tyrosine, play a dual role in human health, inducing oxidative damage and regulating cellular functions. Early and accurate detection of such molecules, such as L-tyrosine in urine, can serve as critical biomarkers for various cancers. In this study, we aimed to enhance the electrochemical detection of these molecules through the synthesis of La2Sn2O7/f-HNT nanocomposites via a simple hydrothermal method. Detailed structural and morphological characterizations confirmed successful synthesis, consistent with our expected outcomes. The synthesized nanocomposites were utilized as nanocatalysts in electrochemical sensors, showing a notable limit of the detection of 0.012 µM for the real-time detection of 3-nitro-l-tyrosine. These findings underscore the potential of nanomaterial-based sensors in advancing early disease detection with high sensitivity, furthering our understanding of cellular oxidative processes.

30 years of American Society for Neural Therapy and Repair (ASNTR): A personal perspective at the intersection of science, politics, and culture.

The American Society for Neural Therapy and Repair (ASNTR) started 30 years ago in 1993 as the American Society for Neural Transplantation (ASNT), with an emphasis on neural transplantation. Through the years, the Society has been shaped as much by our expanding knowledge of neurodegenerative disorders and how to treat them as it has by politics and culture. What once felt like a leash on neuroscience research, has turned into an advantage as neural transplantation evolved into Neural Therapy and Repair. As a Co-Founder this brief commentary provides a personalized account of our research during the Society's years.

High-expansion-ratio PLLA/PDLA/HNT composite foams with good thermally insulating property and enhanced compression performance via supercritical CO2.

It has been a great challenge to prepare high-expansion-ratio polylactide (PLA) foam with eminent thermal insulation and compression performance in packaging field. Herein, a naturally formed nanofiller halloysite nanotube (HNT) and stereocomplex (SC) crystallites were introduced into PLA with a supercritical CO2 foaming method to improve foaming behavior and physical properties. The compressive performance and thermal insulation properties of the obtained poly(L-lactic acid) (PLLA)/poly(D-lactic acid) (PDLA)/HNT composite foams were successfully investigated. At a HNT content of 1 wt%, the PLLA/PDLA/HNT blend foam with an expansion ratio of 36.7 folds showed a thermal conductivity as low as 30.60 mW/(m·K). Meanwhile, the compressive modulus of PLLA/PDLA/HNT foam was 115% higher than that of PLLA/PDLA foam without HNT. Moreover, the crystallinity of PLLA/PDLA/HNT foam was dramatically improved after annealing, thus the results showed that compressive modulus of the annealed foam increased by as high as 72%, while it still maintained good heat insulation with the thermal conductivity of 32.63 mW/(m·K). This work provides a green method for the preparation of biodegradable PLA foams with admirable heat resistance and mechanical performance.

Integration of Bismuth sulfide/functionalized halloysite nanotube composite: An electrochemical tool for diethofencarb analysis.

Diethofencarb (DFC) is a fungicide used in agricultural fields and it's overe use makes a negative impact in the real-time environment. Here in this work, a semi-conductive urchin like Bismuth sulfide (Bi2S3) anchored with tubular structure functionalized halloysite nanotube (F-HNT) was hydrothermally synthesized and used for the electrochemical detection of DFC. Various analytical and microscopic techniques were used to analyze the structure, crystalline nature, and purity of the as-prepared F-HNT@Bi2S3. Moreover, the cyclic voltammetry technique was used to analyze the electrochemical studies of the F-HNT@Bi2S3 modified glassy carbon electrode (GCE). A high synergetic relationship between the Bi2S3 and F-HNT provides a large surface area and better detection of DFC. The amperometry i-t technique result shows that the prepared composite exhibits a wide linear range of 0.0053-526.62 µg L-1, a low detection limit of 0.0032 µg L-1, and very good stability over 2000 s. Notably, our proposed sensor can determine the DFC spiked tomato and water samples with a high recovery range and proven the viability for real-time analysis. Finally, all the above-mentioned study results prove that the F-HNT@Bi2S3 could be used as an electrochemical probe for the detection of DFC.

Synthesis and Optimization of Superhydrophilic-Superoleophobic Chitosan-Silica/HNT Nanocomposite Coating for Oil-Water Separation Using Response Surface Methodology.

In this current study, facile, one-pot synthesis of functionalised nanocomposite coating with simultaneous hydrophilic and oleophobic properties was successfully achieved via the sol-gel technique. The synthesis of this nanocomposite coating aims to develop a highly efficient, simultaneously oleophobic-hydrophilic coating intended for polymer membranes to spontaneously separate oil-in-water emulsions, therefore, mitigating the fouling issue posed by an unmodified polymer membrane. The simultaneous hydrophilicity-oleophobicity of the nanocoating can be applied onto an existing membrane to improve their capability to spontaneously separate oil-in-water substances in the treatment of oily wastewater using little to no energy and being environmentally friendly. The synthesis of hybrid chitosan-silica (CTS-Si)/halloysite nanotube (HNT) nanocomposite coating using the sol-gel method was presented, and the resultant coating was characterised using FTIR, XPS, XRD, NMR, BET, Zeta Potential, and TGA. The wettability of the nanocomposite coating was evaluated in terms of water and oil contact angle, in which it was coated onto a polymer substrate. The coating was optimised in terms of oil and water contact angle using Response Surface Modification (RSM) with Central Composite Design (CCD) theory. The XPS results revealed the successful grafting of organosilanes groups of HNT onto the CTS-Si denoted by a wide band between 102.6-103.7 eV at Si2p. FTIR spectrum presented significant peaks at 3621 cm-1; 1013 cm-1 was attributed to chitosan, and 787 cm-1 signified the stretching of Si-O-Si on HNT. 29Si, 27Al, and 13H NMR spectroscopy confirmed the extensive modification of the particle's shells with chitosan-silica hybrid covalently linked to the halloysite nanotube domains. The morphological analysis via FESEM resulted in the surface morphology that indicates improved wettability of the nanocomposite. The resultant colloids have a high colloid stability of 19.3 mV and electrophoretic mobility of 0.1904 µmcm/Vs. The coating recorded high hydrophilicity with amplified oleophobic properties depicted by a low water contact angle (WCA) of 11° and high oil contact angle (OCA) of 171.3°. The optimisation results via RSM suggested that the optimised sol pH and nanoparticle loadings were pH 7.0 and 1.05 wt%, respectively, yielding 95% desirability for high oil contact angle and low water contact angle.

Enhanced Bioactive Properties of Halloysite Nanotubes via Polydopamine Coating.

Halloysite nanotubes (HNT) were coated five times with dopamine (DOPA) in a tris buffer medium at pH 8.5 to acquire polydopamine-coated HNTs (PDOPA@HNT), e.g., PDOPA1@HNT, PDOPA3@HNT, and PDOPA5@HNT. Upon coating HNT with PDOPA, the surface area, pore volume, and pore size were decreased depending on the number of coatings. While the surface area of HNT was 57.9 m2/g, by increasing the number of coatings from 1 to 5, it was measured as 55.9, 53.4, 53.3, 47.4, and 46.4 m2/g, respectively. The isoelectric point (IEP) for HNTs was determined as 4.68, whereas these values are estimated as 2.31 for PDOPA1@HNTs, 3.49 for PDOPA3@HNT, and 3.55 for PDOPA5@HNT. Three different antioxidant studies were conducted for HNT and PDOPA@HNT, and the total phenol (TPC) value of HNT was found to be 150.5 ± 45.9 µmol gallic acid (GA) equivalent. The TPC values for PDOPA1@HNT, PDOPA3@HNT and PDOPA5@HNT coatings were found to be 405.5 ± 25.0, 750.0 ± 69.9, and 1348.3 ± 371.7 µmol GA equivalents, respectively. The Fe(II) chelation capacity of HNT was found to be 20.5% ± 1.2%, while the PDOPA1@HNT, PDOPA3@HNT and PDOPA5@HNT values were found to be 49.9 ± 6.5, 36.6 ± 12.7 and 25.4 ± 1.2%, respectively. HNT and PDOPA@HNTs inhibited the α-glucosidase (AG) enzyme to greater extents than acetylcholinesterase (AChE). As a result, the DOPA modification of HNTs was rendered to provide additional characteristics, e.g., antioxidant properties and higher AChE and AG enzymes inhibition capabilities. Therefore, PDOPA@HNTs have great potential as biomaterials.

Polymer Hybrid Nanocomposites Based on Homo and Copolymer Xlpe Containing Mineral Nanofillers with Improved Functional Properties Intended for Insulation of Submarine Cables.

Cross-linked polyethylene (XLPE) is one of the most popular insulation materials used in the production of medium and high voltage cables (MV, HV). This article presents the results of research carried out on two types of commercially used insulation materials, modified with the addition of organophilic phyllosilicate (CLOISITE C20A)and halloysite nanotubes (HNTs). The influence of fillers on the mechanical properties of insulating materials is discussed as a potential mechanism for increasing their resistance to the phenomenon of water-tree. SEM and XRD analyses were performed to investigate the morphology and DSC for comparing phase transitions. Mechanical and functional properties for different concentrations of nanofillers, such as their hybrids, were also investigated.

Composition optimization of PLA/PPC/HNT nanocomposites for mandibular fixation plate using single-factor experimental design.

The need to overcome the secondary surgery to remove implanted metal fixation plate leads to the idea of replacing the material with degradable bionanocomposite. In this research, polylactic acid/polypropylene (PLA/PPC) blends incorporated with halloysite nanotubes (HNT) (0-6 wt %) were considered as the candidate material for mandibular fixation plate. A single-factor design using Design Expert software was used to determine 20 different compositions of PLA/PPC/HNT nanocomposites and their mechanical properties were then measured. The optimization of the PLA/PPC/HNT nanocomposite composition was performed based on the nanocomposite's response to Young's modulus, tensile strength, and elongation at break. Further analysis suggested an optimum composition of 92.5/7.5 PLA/PPC with 6 wt % of HNT. The statistical results predicted that there was a 71.7% possibility that the proposed nanocomposite would have the following mechanical properties: Young's modulus of 2.18 GPa, a tensile strength of 64.16 MPa, and an elongation at break of 106.53%.

A Novel Efficient Piscine Oral Nano-Vaccine Delivery System: Modified Halloysite Nanotubes (HNTs) Preventing Streptococcosis Disease in Tilapia (Oreochromis sp.).

Generally, the injection method is recommended as the best efficient method for vaccine applications in fish. However, labor-intensive and difficult injection for certain fish sizes is always considered as a limitation to aquatic animals. To demonstrate the effectiveness of a novel oral delivery system for the piscine vaccine with nano-delivery made from nano clay, halloysite nanotubes (HNTs) and their modified forms were loaded with killed vaccines, and we determined the ability of the system in releasing vaccines in a mimic digestive system. The efficaciousness of the oral piscine vaccine nano-delivery system was evaluated for its level of antibody production and for the level of disease prevention in tilapia. Herein, unmodified HNTs (H) and modified HNTs [HNT-Chitosan (HC), HNT-APTES (HA) and HNT-APTES-Chitosan (HAC)] successfully harbored streptococcal bivalent vaccine with inactivated S. agalactiae, designated as HF, HAF, HCF and HACF. The releasing of the loading antigens in the mimic digestive tract demonstrated a diverse pattern of protein releasing depending on the types of HNTs. Remarkably, HCF could properly release loading antigens with relevance to the increasing pH buffer. The oral vaccines revealed the greatest elevation of specific antibodies to S. agalactiae serotype Ia in HCF orally administered fish and to some extent in serotype III. The efficacy of streptococcal disease protection was determined by continually feeding with HF-, HAF-, HCF- and HACF-coated feed pellets for 7 days in the 1st and 3rd week. HCF showed significant RPS (75.00 ± 10.83%) among the other tested groups. Interestingly, the HCF-treated group exhibited noticeable efficacy similar to the bivalent-vaccine-injected group (RPS 81.25 ± 0.00%). This novel nano-delivery system for the fish vaccine was successfully developed and exhibited appropriated immune stimulation and promised disease prevention through oral administration. This delivery system can greatly support animals' immune stimulation, which conquers the limitation in vaccine applications in aquaculture systems. Moreover, this delivery system can be applied to carrying diverse types of biologics, including DNA, RNA and subunit protein vaccines.

Tensile Modulus of Polymer Halloysite Nanotube Systems Containing Filler-Interphase Networks for Biomedical Requests.

To date, there have been a limited number of studies modeling the tensile modulus in the polymer halloysite nanotube (HNT) systems before or after percolation onset. In this paper, an equation for a composite's modulus post-percolation onset was developed for HNT-filled samples including the interphase and HNT network. The dispersed nanoparticles and adjoining interphase part were neglected, because they caused ineffective influences on the stiffness of the system after percolation onset. The developed model reflects the impacts of HNTs' size, interphase depth, percolation onset and the volume shares and moduli of the HNT network and its adjacent interphase on the modulus of HNT-based systems. The impacts of issues on the nanocomposite modulus are defendable, confirming the effectiveness of the developed model. HNT length, interphase depth, HNT concentration, net modulus and net portion directly influenced the stiffness, while the HNT radius and percolation onset had inverse effects. Results show that there was a 142% improvement in the modulus of samples at an interphase depth of 40 nm. Moreover, the stiffness improved by 60% at a net modulus of 200 GPa, but it later exhibited a 180% enhancement at a net modulus of 1000 GPa. In addition, the experimental data for the modulus of numerous composites display fine agreement to the predictions, confirming the validity of the developed model.

Rapid and non-invasive surface-enhanced Raman spectroscopy (SERS) detection of chlorpyrifos in fruits using disposable paper-based substrates charged with gold nanoparticle/halloysite nanotube composites.

Chlorpyrifos is one of the most widely used organophosphate insecticides in agricultural production. Nevertheless, the residues of chlorpyrifos in agricultural by-product seriously threaten human health. Thus, the ultrasensitive detection of chlorpyrifos residues in agri-food products is of great demand. Herein, an AuNP/HNT-assembled disposable paper SERS substrate was prepared by an electrostatic self-assembly method to detect chlorpyrifos residues. The AuNP/HNT paper substrate exhibited high SERS activity, good reproducibility, and long-term stability, which was successfully used for quantitative detection of chlorpyrifos; the detection limit reached 7.9 × 10-9 M. For spiked apple samples the calculated recovery was 87.9% with a RSD value of 6.1%. The excellent detection ability of AuNP/HNT paper-based SERS substrate indicated that it will play an important role in pesticide detection in the future. AuNP/HNT assembled disposable paper SERS substrate was prepared by an electrostatic self-assembly method to detect chlorpyrifos residues in fruits.

Mechanistic insights of hexavalent chromium remediation by halloysite-supported copper nanoclusters.

Chromium (Cr) pollution is a significant environmental concern with remediation challenge. Hexavalent chromium (Cr(VI)) is more toxic than trivalent chromium (Cr(III)) due to its mutagenicity and oncogenicity. In this investigation, a multi-functional material, copper nanoclusters (CuNCs)-halloysite nanotubes (HNT) composite (CuNCs@HNT), has been synthesised in an eco-friendly manner and utilised for Cr(VI) remediation. Advanced analytical tools confirmed the seeding of ultra-fine CuNCs onto HNT surfaces. The maximum adsorption capacity of CuNCs@HNT is 79.14 ± 6.99 mg/g at pH 5 ± 0.1 with an increment at lower pHs. This performance was comparable for real surface stream water as well as other reported materials. The pseudo-second-order kinetic-, intra-particle diffusion- and Freundlich isotherm models well fit the experimental data implying that the chemisorption, multiphase diffusion and multi-molecular layer distribution occurred during adsorption. The Fourier-transform infrared and the x-ray photoelectron spectra also ensured the transformation of Cr(VI) to Cr(III) indicating the material's suitability for concurrent adsorption and reduction of Cr(VI). While coexisting cations and anions did not overwhelm this adsorption, CuNCs@HNT was regenerated and reused five successive times in adsorption-desorption cycles without significant loss of adsorption capacity and material's integrity. Therefore, this multi-functional, biocompatible, low-cost and stable CuNCs@HNT composite may have practical application for similar toxic metals remediation.

In-Out Surface Modification of Halloysite Nanotubes (HNTs) for Excellent Cure of Epoxy: Chemistry and Kinetics Modeling.

In-out surface modification of halloysite nanotubes (HNTs) has been successfully performed by taking advantage of 8-hydroxyquinolines in the lumen of HNTs and precisely synthesized aniline oligomers (AO) of different lengths (tri- and pentamer) anchored on the external surface of the HNTs. Several analyses, including FTIR, H-NMR, TGA, UV-visible spectroscopy, and SEM, were used to establish the nature of the HNTs' surface engineering. Nanoparticles were incorporated into epoxy resin at 0.1 wt.% loading for investigation of the contribution of surface chemistry to epoxy cure behavior and kinetics. Nonisothermal differential scanning calorimetry (DSC) data were fed into home-written MATLAB codes, and isoconversional approaches were used to determine the apparent activation energy (Eα) as a function of the extent of cure reaction (α). Compared to pristine HNTs, AO-HNTs facilitated the densification of an epoxy network. Pentamer AO-HNTs with longer arms promoted an Excellent cure; with an Eα value that was 14% lower in the presence of this additive than for neat epoxy, demonstrating an enhanced cross-linking. The model also predicted a triplet of cure (m, n, and ln A) for autocatalytic reaction order, non-catalytic reaction order, and pre-exponential factor, respectively, by the Arrhenius equation. The enhanced autocatalytic reaction in AO-HNTs/epoxy was reflected in a significant rise in the value of m, from 0.11 to 0.28. Kinetic models reliably predict the cure footprint suggested by DSC measurements.

A Novel Composite Material UiO-66@HNT/Pebax Mixed Matrix Membranes for Enhanced CO2/N2 Separation.

Mixing a polymer matrix and nanofiller to prepare a mixed matrix membrane (MMM) is an effective method for enhancing gas separation performance. In this work, a unique UiO-66-decorated halloysite nanotubes composite material (UiO-66@HNT) was successfully synthesized via a solvothermal method and dispersed into the Pebax-1657 matrix to prepare MMMs for CO2/N2 separation. A remarkable characteristic of this MMM was that the HNT lumen provided the highway for CO2 diffusion due to the unique affinity of UiO-66 for CO2. Simultaneously, the close connection of the UiO-66 layer on the external surface of HNTs created relatively continuous pathways for gas permeation. A suite of microscopy, diffraction, and thermal techniques was used to characterize the morphology and structure of UiO-66@HNT and the membranes. As expected, the embedding UiO-66@HNT composite materials significantly improved the separation performances of the membranes. Impressively, the as-obtained membrane acquired a high CO2 permeability of 119.08 Barrer and CO2/N2 selectivity of 76.26. Additionally, the presence of UiO-66@HNT conferred good long-term stability and excellent interfacial compatibility on the MMMs. The results demonstrated that the composite filler with fast transport pathways designed in this study was an effective strategy to enhance gas separation performance of MMMs, verifying its application potential in the gas purification industry.

Superior galvanostatic electrochemical deposition of platinum nanograss provides high performance planar microelectrodes forin vitroneural recording.

Objective.Platinum nanograss (Ptng) has been demonstrated as an excellent coating to increase the electrode roughness and reduce the impedance of microelectrodes for neural recording. However, the optimisation of the original potentiostatic electrochemical deposition (PSED) method has been performed by the original group only and noin vitrovalidation of functionality was reported.Approach.This study firstly reinvestigates the use of the PSED method for Ptng coating at different charge densities which highlights non-uniformities in the edges of the microelectrodes for increasing deposition charge densities, leading to a decreased impedance which is in fact an artefact. We then introduce a novel Ptng fabrication method of galvanostatic electrochemical deposition (GSED).Main results.We demonstrate that the GSED deposition method also significantly reduces the electrode impedance, raises the charge storage capacity and provides a significantly more planar electrode surface in comparison to the PSED method with negligible edge effects. In addition, we demonstrate how high-quality neural recordings were performed, for the first time, using the Ptng GSED deposition microelectrodes from human hNT neurons and how spiking and bursting were observed.Significance.Thus, the GSED Ptng deposition method presented here provides an alternative method of microelectrode fabrication for neural applications with excellent impedance and planarity of surface.

Fabrication of Bio-Nanocomposite Based on HNT-Methionine for Controlled Release of Phenytoin.

In this study, a novel promising approach for the fabrication of Halloysite nanotube (HNT) nanocomposites, based on the amino acid named Methionine (Met), was investigated. For this purpose, Met layered on the outer silane functionalized surface of HNT for controlled release of Phenytoin sodium (PHT). The resulting nanocomposite (MNT-g-Met) was characterized by FTIR, XRD, Zeta potential, TGA, TEM and FE-SEM. The FT-IR results showed APTES and Met peaks, which proved the modification of the HNTs. The zeta-potential results showed the interaction between APTES (+53.30) and Met (+38.80) on the HNTs (-30.92). The FE-SEM micrographs have displayed the grafting of Met on the modified HNTs due to the nanotube conversion to a rough and indistinguishable form. The amount of encapsulation efficiency (EE) and loading efficiency (LE) of MNT-g-Met was 74.48% and 37.24%, while pure HNT was 57.5%, and 28.75%, respectively. In-vitro studies showed that HNT had a burst release (70% in 6 h) in phosphate buffer while MNT-g-Met has more controlled release profile (30.05 in 6 h) and it was found to be fitted with the Korsmeyer-Peppas model. Due to the loading efficiency and controlled release profile, the nanocomposite promote a good potential for drug delivery of PHT.

Influence of the Halloysite Nanotube (HNT) Addition on Selected Mechanical and Biological Properties of Thermoplastic Polyurethane.

Halloysite nanotube (HNT) additions to the thermoplastic polyurethane (TPU) system were thoroughly evaluated in this study. The resultant composites have been designed for future personalized intervertebral disc implant applications, which requires additional technology to obtain the appropriate geometry unique to each patient. These requirements can be fulfilled using 3D printing. In this work, a technology was developed to produce filaments for fused deposition modeling (FDM). Nanocomposites were prepared using variable HNT content (1, 2, and 3 wt.%). The nanostructure of the resultant composites was confirmed using scanning transmission electron microscopy (STEM). Mechanical tests were used to measure the tensile modulus, stress, and elongation the composites and TPU matrix. Nanocomposites with 2% HNT content were able to withstand 26% increased stress and 50% increased elongation compared to pure TPU before fracturing in addition to a 13% reduction in the friction coefficient. A MTT cytotoxicity assay confirmed the cytotoxicity of all tested materials against human epidermal keratinocyte cells (HaCaT).

Investigating Halloysite Nanotubes as a Potential Platform for Oral Modified Delivery of Different BCS Class Drugs: Characterization, Optimization, and Evaluation of Drug Release Kinetics.

PURPOSE: This study systematically investigated the potential of four model drugs (verapamil HCl, flurbiprofen, atenolol, and furosemide), each belonging to a different class of Biopharmaceutics Classification Systems (BCS) to be developed into oral modified release dosage forms after loading with halloysite nanotubes (HNTs). METHODS: The drugs were studied for their loading (mass gain %) by varying solvent system, method, pH, and ratios of loading into the nanotubes using D-optimal split-plot design with the help of Design Expert software. Drug-loaded halloysites were characterized by XRD, DTA, FTIR, SEM, and HPLC-UV-based assay procedures. Dissolution studies were also performed in dissolution media with pH 1.2, 4.5, and 6.8. Moreover, the optimized samples were evaluated under stress stability conditions for determining prospects for the development of oral dosage forms. RESULTS: As confirmed with the results of XRD and DTA, the drugs were found to be converted into amorphous form after loading with halloysite (HNTs). The drugs were loaded in the range of ~7-9% for the four drugs, with agitation providing satisfactory and equivalent loading as compared to vacuum plus agitation based reported methods. FTIR results revealed either only weak electrostatic (verapamil HCl and flurbiprofen) or no interaction with the surface structure of the HNTs. The dissolution profiling depicted significantly retarded release of drugs with Fickian diffusion from a polydisperse system as a model that suits well for the development of oral dosage forms. HPLC-UV-based assay indicated that except furosemide (BCS class IV), the other three drugs are quite suitable for development for oral dosage forms. CONCLUSION: The four drugs investigated undergo phase transformation with HNTs. While agitation is an optimum method for loading drugs with various physicochemical attributes into HNTs; solvent system, loading ratios and pH play an important role in the loading efficiency respective to the drug properties. The study supports the capability of developing HNT-based modified release oral dosage forms for drugs with high solubility.