Nanocellulose fibres are known to enhance the mechanical properties of biopolymers when added as a filler. Nanocellulose irreversibly agglomerates upon drying and is therefore sold as an aqueous gel or suspension, increasing shipping cost and limiting application. This work studied the utility of xanthan gum as a dispersant aid for dried nanocellulose fibres. At levels as low as 15% xanthan gum addition, based on the mass of nanocellulose, prior to drying, agglomeration was significantly decreased. Mild shear rates could disperse the dried nanocellulose to a similar degree as ultrasonication when xanthan gum was present. Several complementary techniques, such as rheology, turbidimetry, and SEM- and TEM-imaging, proved that the native nanocellulose properties could be recovered after drying. Xanthan gum and nanocellulose, when incorporated into thermoplastic starch, showed a synergistic effect regarding the increase in tensile strength of the resultant biopolymer film. The addition of previously dried nanocellulose/xanthan, in a 4:1 ratio, to thermoplastic starch at a starch-cellulose ratio of 20:1, increased the tensile strength from 5.4 to 23.0 MPa. The ability to produce a dispersible and dry nanocellulose product that retains its properties has clear commercial benefits.

The scarcity of age-appropriate pharmaceutical formulations is one of the major challenges impeding successful management of tuberculosis (TB) prevalence in minors. To this end, we designed and assessed the quality of a multiparticulate reconstitutable suspension powder containing fixed dose rifampicin and pyrazinamide (150 mg/300 mg per 5 mL) which was prepared employing solid–liquid direct dispersion coupled with timed dehydration, and mechanical pulverization. The optimized formulation had a high production yield (96.000 ± 3.270%), displayed noteworthy powder flow quality (9.670 ± 1.150°), upon reconstitution the suspension flow property was non-Newtonian and was easily redispersible with gentle manual agitation (1.720 ± 0.011 strokes/second). Effective drug loading was attained for both pyrazinamide (97.230 ± 2.570%w/w) and rifampicin (97.610 ± 0.020%w/w) and drug release followed a zero-order kinetic model (R2 = 0.990) for both drugs. Microscopic examinations confirmed drug encapsulation efficiency and showed that the particulates were micro-dimensional in nature (n < 700.000 µm). The formulation was physicochemically stable with no chemically irreversible drug-excipient interactions based on the results of characterization experiments performed. Findings from organoleptic evaluations generated an overall rating of 4.000 ± 0.000 for its attractive appearance and colour 5.000 ± 0.000 confirming its excellent taste and extremely pleasant smell. Preliminary cytotoxicity studies showed a cell viability above 70.000% which indicates that the FDC formulation was biocompatible. The optimized formulation was environmentally stable either as a dry powder or reconstituted suspension. Accordingly, a stable and palatable FDC antimycobacterial reconstitutable oral suspension powder, intended for flexible dosing in children and adolescents, was optimally fabricated.

Abstract The effects of filler content, filler particle size and surface coating, as well as the natures of the wax and metal stearate lubricants on the properties of calcium carbonate-filled linear low-density polyethylene compounds were investigated. The elongation at break decreased exponentially with filler loading irrespective of whether the filler was surface coated or not. The corresponding decline in the impact strength was more gradual but it dropped abruptly on reaching a filler loading of 70 wt%. The effect of shear rate on the apparent melt viscosity followed an empirically modified Carreau–Yasuda model which included the effect of filler content. It features the zero-shear viscosity and the flow consistency index as adjustable parameters. These characterize the viscosity trends at low- and high-shear rates, respectively. In the absence of additives, the melt viscosity at 60 wt% filler exceeded that of the neat polymer by a factor of three. Adding 3 wt% wax and 1.0 wt% zinc stearate returned the melt viscosity to levels just above that of the neat polymer. Calcium stearate and magnesium stearate were less effective at reducing the apparent melt viscosity but a blend of the latter with zinc stearate performed particularly well.

A novel method for the visualization and quantification of the state of dispersion of calcium carbonate particles in thin blown polymer films is described. Particle imaging was achieved by elemental mapping using energy dispersive spectroscopy. This generated outlines of particles and agglomerates located close to the film surface. ImageJ software facilitated the extraction of the corresponding Feret diameters. Finally, the Bootstrap technique was used to estimate confidence intervals for the kurtosis of the Feret particle size distribution. Kurtosis is a statistic that describes the shape of a distribution's tails in relation to its overall shape. It therefore provides a measure that characterizes the degree of particle agglomeration. The proposed procedure was applied to analyze high-density polyethylene films prepared using different calcium carbonate masterbatches in which formulation parameters were varied.

The potential of a blended cellulose solvent, consisting of a 1:1 mass ratio of choline chloride with the ionic liquid 1-ethyl-3-methylimadazolium acetate, was evaluated by using a film-casting technique. When comparing films produced with the neat ionic liquid to casting products from the mixed solvent, mechanical properties could largely be retained, while transparency was somewhat impaired. This is attributed to a fibrous microstructure and a higher degree of crystallinity caused by incomplete dissolution of the initial cellulose fibres. The presence of these residual fibres significantly reduced shrinkage during the film formation process. Functional group analyses, together with information on their crystallographic structure, proved that these film-like products should be classified as all-cellulose composites (ACCs). Statistical analyses of tensile properties justify further research on the mixed solvent system for cellulose processing.

This study aimed to develop cellulose-based polymer matrices as controlled release devices for plant-based insect repellents and attractants, with the aim of finding sustainable and environmentally friendly pest control methods for agricultural applications. Citronellol, terpineol and methyl salicylate were the selected active compounds for this study. Their compatibility with cellulose diacetate was predicted using Hansen Solubility Parameters, which predicted terpineol as the most compatible with cellulose diacetate, followed by methyl salicylate and citronellol. This was consistent with the plasticization efficiency trend from DMA results of solvent cast cellulose diacetate films containing the active compounds. The chemical identity of the films and cellulose diacetate-active compound intermolecular interactions were verified by FTIR. TGA demonstrated the thermal stability of cellulose diacetate/active compound/clay formulations at temperatures not exceeding 170 °C. Cellulose diacetate/organoclay nanocomposite matrices containing the active compounds at 35 wt-% were prepared by twin screw extrusion compounding, with the active compounds also functioning as plasticizers. The amount of active compound in the strands was determined by solvent extraction and TGA. Both methods showed that small amounts of active compound were lost during the compounding process. SEM demonstrated the effect of organoclay on the internal morphology of the matrix, whereas TEM showed clay dispersion and intercalation within the matrix. The matrix served as a reservoir for the active compounds while simultaneously controlling their release into the environment. Release profiles, obtained through oven ageing at 40 °C for 70 days, were fitted to existing Log-logistic and Weibull models, and novel Diffusion and Modified Weibull release models. Citronellol was released the fastest, followed by methyl salicylate and terpineol. The findings suggest that cellulose diacetate/organoclay strands are promising controlled-release matrices for pest control purposes.

Colomerus vitis is a pest of grapevine worldwide that includes three strains recognised by plant symptoms (bud, erineum, and leaf curl), which could represent cryptic species. We approached this long-standing question by integrating genetic and morphological methods. COI sequences of mites from South Africa and other countries showed five phylogenetic groups (G1 to G5) with intergroup p-distances up to 23% and intragroup divergence lower than 2%. The three groups found in South Africa (G1, G2, and G3) were screened from a variety of grapevine samples using a novel multiplex PCR method. Only G1 and G3 were significantly associated with erinea and buds, respectively, and the three groups were frequently co-present in the same plant sample. Cryo-SEM showed adults with five- and six-rayed empodia, variable microtubercle shape, and prodorsal shield patterns. Specimens with six-rayed empodia and a smooth prodorsal shield were more often associated with buds, while specimens from erinea were variable. These results support the genetic evidence in that particular groups or morphotypes are not associated exclusively with specific plant niches. We propose that C. vitis is a complex of at least five genetically distinct but morphologically similar species, and that no one species can be assigned to a particular grapevine symptom.

A pursuit to find a healthy alternative to sucrose with less cariogenic potential, which can potentially lower the incidence of Early Childhood Caries (ECC), by means of comparison. Primary tooth enamel blocks (n=32) were randomly divided into four groups and exposed to 5% concentrations of the respective test groups (sucrose, xylitol, erythritol and stevia). All samples were inoculated with S. mutans standard strain (ATCC 25175) at room temperature. Analysis of Colony Forming Units (CFUs), acidity measurements (pH) and Scanning Electron Microscopy (SEM) observations were done after 6, 12, 18 and 24 h and compared. After 6 h, the marginal mean CFU count indicated equal S. mutans growth in all groups. Stevia showed lower CFU counts compared to other groups at 12, 18 and 24 h. The pH levels for all non-fermentable sugar substitutes (NSS) initially decreased but never below the critical pH=5.5 and stabilized from 12 to 18 h. The pH levels of sucrose dropped and remained below pH=5.5 at all time intervals. The SEM analysis of S. mutans supported the CFU results indicating growth in the presence of sucrose and reduction in the presence of the NSS.Compared to sucrose, xylitol, erythritol and stevia have less cariogenic potential with reduced growth of S. mutans and subsequent acidity levels. Stevia had the least cariogenic potential of all the NSS tested, followed by erythritol and then xylitol.

The study investigated the toxicity effects of ‘form specific’ engineered nanomaterials (ENMs) and ions released from nano-enabled products (NEPs), namely sunscreens, sanitisers, body creams and socks on Pseudokirchneriella subcapitata, Spirodela polyrhiza, and Daphnia magna. Additionally, risk estimation emanating from the exposures was undertaken. The ENMs and the ions released from the products both contributed to the effects to varying extents, with neither being a uniform principal toxicity agent across the exposures; however, the effects were either synergistic or antagonistic. D. magna and S. polyrhiza were the most sensitive and least sensitive test organisms, respectively. The most toxic effects were from ENMs and ions released from sanitisers and sunscreens, whereas body creams and sock counterparts caused negligible effects. The internalisation of the ENMs from the sunscreens could not be established; only adsorption on the biota was evident. It was established that ENMs and ions released from products pose no imminent risk to ecosystems; instead, small to significant adverse effects are expected in the worst-case exposure scenario. The study demonstrates that while ENMs from products may not be considered to pose an imminent risk, increasing nanotechnology commercialization may increase their environmental exposure and risk potential; therefore, priority exposure cases need to be examined.

Metal stearate blends are potential lubricants and filler dispersants in polymer compounding. Therefore, the thermal phase behaviour of binary blends of calcium stearate and magnesium stearate with zinc stearate was investigated. Cooling curve studies indicated lower melting temperatures in both systems. X-ray diffraction studies revealed that this was due to the formation of solid solutions of variable composition rather than to eutectic formation. Rheology measurements showed that true fluidification only happened well above the apparent melting points established from cooling curves. Calcium carbonate filled polyethylene containing metal stearate mixtures showed lower melt viscosities than were achievable using only calcium- or magnesium stearate as the lubricant. These results suggest that metal stearate blends, in combination with a judiciously selected wax component, may offer advantages in lowering compound melt viscosity and facilitating better particle dispersion.

Abstract Nanocomposite strands with mosquito repellent DEET or Icaridin incorporated in a poly(ethylene‐co‐vinyl acetate) (EVA) matrix, with either pyrogenic silica or an organoclay as a nanofiller, were prepared by a twin‐screw extrusion compounding technique. The nature and levels of the repellent and nanofiller that was used affected the material phase morphology. The repellent release was followed as a function of aging time in convection ovens set at 30 and 50°C. The experimental release data of the mosquito repellent from the microporous polymer swellable matrix strands was mathematically modeled and fitted using a range of semi‐empirical models. In the majority of case, the Korsmeyer‐Peppas power law model provided the best data fit. As expected, the wide range of internal morphologies also resulted in quite different release profiles. These models were found to be valuable as they provided insights into the mechanism of repellent release from EVA swellable matrices. It was possible to differentiate between diffusion and relaxation mechanisms. Surprisingly, strands containing nominally more than 30 wt% Icaridin showed accelerating mass loss during the initial phase, consistent with Super Case II transport. Diffusional exponents as high as 1.81 were found. Furthermore, the internal microporous region of the extruded EVA strands was covered by a surface membrane that acted a diffusion barrier that, in effect, controlled the release rate of the mosquito repellents. Some of the investigated samples exhibited release profiles that suggest that longer lasting effective release of repellents is possible than currently achieved by available commercially products.

Deep eutectic solvents aid the formulation of solid pesticide dosage forms for water-insoluble actives. This was demonstrated by encapsulating Amitraz powder in a low-melting matrix based on the eutectic mixture of urea (32 wt%) and 1,3-dimethylurea. Dissolution in water of melt-cast discs, containing 20 wt% active, led to the rapid release of Amitraz in a finely dispersed form. The order of magnitude reduction in particle size, after dissolution, is ascribed to the solubilization of Amitraz in the hot deep eutectic solvent and its subsequent precipitation as a separate phase on crystallization of the matrix.

Malaria remains a public health concern with vector control still the vital component of disease prevention, control, and elimination strategies. Recent years has seen a “stalling” in the progress made towards the reduction in the global malaria burden, highlighting the need to develop new, innovative, and safe alternative tools and delivery systems to achieve global malaria elimination. Interventions based on the use of indoor residual spraying (IRS) and long-life insecticidal bed nets (LLINs), i.e. insecticide-containing wall linings (IWLs), can contribute towards the reduction of malaria. Both LLINs and IWLs rely on the presence of insecticides on the fibre or filament surfaces. However, materials directly incorporating the insecticides into the polymer melt during extrusion, allows for effective killing of the mosquitoes when they come into contact with the surface of the material, only if there is insecticide present there. This means that the insecticide must migrate to the surface and precipitate there (bloom). Over time the internal concentration of insecticide will decay. This investigation was done using Fourier transform infrared spectroscopy (FTIR) in both the transmission and attenuated total reflection (ATR) modes to better understand the blooming of three World Health Organization-approved contact insecticides, i.e. alphacypermethrin, fipronil and chlorfenapyr, from mesh or film to better understand the likeliness of insecticides within the materials to migrate to the surface. Film-based samples were prepared in addition to wall lining mesh, because of their easier characterisation than the irregular shaped mesh filaments. FTIR, in ATR and in transmission modes, enabled the tracking of the migration of the three insecticides, over time to the surface of polyethylene mesh or film. This made it possible to estimate the apparent solubility of the insecticides in the polymer matrix. However, scanning electron microscopy (SEM) revealed that a portion of the insecticide is trapped, in a crystalline state, inside the polymer matrix. These results suggest the possibility of developing products-based insecticides for protection against infective mosquito bites in malaria-endemic regions.

The severity of tuberculosis (TB) in children is considered a global crisis compounded by the scarcity of pharmaceutical formulations suitable for pediatric use. The purpose of this study was to optimally develop and evaluate a pyrazinamide containing edible orodispersible film formulation potentially suitable for use in pediatrics actively infected with TB. The formulation was prepared employing aqueous-particulate blending and solvent casting methods facilitated by a high performance Box Behnken experimental design template. The optimized orodispersible formulation was mechanically robust, flexible, easy to handle, exhibited rapid disintegration with initial matrix collapse occurring under 60 s (0.58 ± 0.05 min ≡ 34.98 ± 3.00 s) and pyrazinamide release was controlled by anomalous diffusion coupled with matrix disintegration and erosion mechanisms. It was microporous in nature, light weight (57.5 ± 0.5 mg) with an average diameter of 10.5 mm and uniformly distributed pyrazinamide load of 101.13 ± 2.03 %w/w. The formulation was physicochemically stable with no evidence of destructive drug–excipient interactions founded on outcomes of characterization and environmental stability investigations. Preliminary inquiries revealed that the orodispersible formulation was cytobiocompatible, palatable and remained intact under specific storage conditions. Summarily, an edible pyrazinamide containing orodispersible film formulation was optimally designed to potentially improve TB pharmacotherapy in children, particularly the under 5 year olds.

Safe application of water-insoluble acaricides requires fast release from solid dosage systems into aquatic environments. Dextrin is a water-soluble form of partially hydrolyzed starch, which may be used as matrix material for these systems if retrogradation can be inhibited by the inclusion of nanofillers. Several glycerol-plasticized thermoplastic dextrin-based nanocomposites were prepared with a twin-screw extrusion-compounding process. The nanofillers included a layered double hydroxide (LDH), cellulose nanofibers (CNF), and stearic acid. The time-dependent retrogradation of the compounds was monitored by X-ray diffraction (XRD) and dynamic mechanical thermal analysis (DMA). XRD showed that composite samples that included stearic acid in the formulation led to the formation of an amylose-lipid complex and a stable crystallinity during aging. The most promising nanocomposite included both stearic acid and CNF. It was selected as the carrier material for the water-insoluble acaricide Amitraz. Fast release rates were observed for composites containing 5, 10, and 20% (w/w) of the pesticide. A significant reduction in the particle size of the released Amitraz powder was observed, which is ascribed to the high-temperature compounding procedure.

During melt extrusion of nanocomposites, nanoparticles can be incorporated either directly or through the masterbatch, which brings up a simple question of how the mode of nanoparticle inclusion affects the morphology and hence the rheological properties of the final composite. In the study reported here, nylon6/ethyl–vinyl-alcohol (N6/EVOH) was selected to model a blend system, and the effect of the mode of organoclay inclusion on the morphology development and melt-state viscoelastic properties of ternary blend composites was investigated. The morphological study using scanning electron microscopy, transmission electron microscopy, three-dimensional tomography, and differential scanning calorimetry indicated that the intercalated silicate layers were located in the interphase region between N6 and EVOH in the N6/EVOH/masterbatch composite and core–shell particles were formed, with EVOH as the core. On the other hand, the intercalated silicate layers were well distributed in the blend matrix of the N6/EVOH/organoclay composite, and it was difficult to differentiate between two phases. Finally, the different morphological developments were correlated with the melt-state rheological properties of the composites to evaluate the processing and product performance. The results showed that the masterbatch played an important role in establishing the compatibility of N6 and EVOH, and it could impede the gel formation that would benefit processing and product development.

The combination of polymeric nanoparticles (NPs) as a core and lipid vesicles as a shell has emerged to be a robust and promising drug delivery strategy. This study explores the development of a novel combined delivery system where poly d,l, lactic-co-glycolic acid (PLGA) NPs are entrapped within Pheroid® drug delivery system. The solid NPs were combined with the Pheroid® vesicles using two different methods: pre-mix and post-mix. The surface properties of the PLGA NPs were altered through the inclusion (pos-NPs) and exclusion (neg-NPs) of chitosan (CT) and polyethylene glycol (PEG), to evaluate their interaction with the Pheroid® Vesicles. The average particle size of the novel NP–Pheroid® combined system ranged from approximately 1990–2450 nm while the zeta potential (ZP) ranged from −18 to −30 mV, measured using dynamic light scattering (DLS) and electrophoretic velocity techniques, respectively. The NP/Pheroid® mixing ratio experiment indicated that a maximum of 2.5% (w/v) NPs can be optimally added to the Pheroid® vesicles without compromising the structure and the stability of the NP–Pheroid® combined system. Visual analysis of this system was done through transmission electron microscopy (TEM), cryogenic (cryo) TEM and confocal laser scanning microscopy (CLSM) techniques to obtain adequate information of this novel combined drug delivery system which includes the localization of the PLGA NPs with the Pheroid ® vesicles.

Quaternary imidazolium salts with varying alkyl chain lengths (octyl, decyl, dodecyl, tetradecyl, hexadecyl) were synthesized and characterized with nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopy. Antibacterial screening experiments revealed that the activity decreased with increasing alkyl chain length. Quaternary imidazolium salts with alkyl chains, such as octyl and decyl, were used for the modification of montmorillonite (Mt). The characterization of the modified Mts was performed using XRD, TGA and TEM, and results showed that the surfactants were successfully intercalated in the Mt interlayer space. The selected quaternary imidazolium salt-modified Mts were evaluated for water disinfection using distilled, borehole and river water inoculated with Escherichia coli. Mt modified with surfactants carrying the octyl chains displayed excellent disinfection properties for all three water types. The TEM results showed that the mechanism of inactivation occurred through rupturing of the cell membrane after the E. coli cells came into contact with the modified Mt. In summary, the quaternary imidazolium-modified Mt has great potential to be used for household water disinfection.

To improve traditional cancer therapies, we synthesized polylactide (PLA) spheres coencapsulating magnetic nanoparticles (MNPs, Fe3O4) and an anticancer drug (doxorubicin, DOX). The synthesis process involves the preparation of Fe3O4 NPs by a coprecipitation method and then PLA/DOX/Fe3O4 spheres using the solvent evaporation (oil-in-water) technique. The Fe3O4 NPs were coated with oleic acid to improve their hydrophobicity and biocompatibility for medical applications. The structure, morphology and properties of the MNPs and PLA/DOX/Fe3O4 spheres were studied using various techniques, such as FTIR, SEM, TEM, TGA, VSM, UV-vis spectroscopy, and zeta potential measurements. The in vitro DOX release from the spheres was prolonged, sustained, and pH-dependent and fit a zero-order kinetics model and an anomalous mechanism. Interestingly, the spheres did not show a DOX burst effect, ensuring the minimal exposure of the healthy cells and an increased drug payload at the tumor site. The pronounced biocompatibility of the PLA/DOX/Fe3O4 spheres with HeLa cells was proven by a WST assay. In summary, the synthesized PLA/DOX/Fe3O4 spheres have the potential for magnetic targeting of tumor cells to transform conventional methods.