Objective: Solventless dry powder coating methods have many advantages compared to solvent-based methods: they are more economical, simpler, safer, more environmentally friendly and easier to scale up. The purpose of this study was to investigate a highly effective dry powder coating method using the mechanofusion system, a mechanochemical treatment equipped with high compressive and shearing force.Materials and methods: Acetaminophen (AAP) and carnauba wax (CW) were selected as core particles of the model drug and coating material, respectively. Mixtures of AAP and CW with and without talc were processed using the mechanofusion system.Results: Sustained AAP release was observed by selecting appropriate processing conditions for the rotation speed and the slit size. The dissolution rate of AAP processed with CW substantially decreased with an increase in talc content up to 40% of the amount of CW loaded. Increasing the coating amount by two-step addition of CW led to more effective coating and extended drug release. Scanning electron micrographs indicated that CW adhered and showed satisfactory coverage of the surface of AAP particles.Conclusion: Effective CW coating onto the AAP surface was successfully achieved by strictly controlling the processing conditions and the composition of core particles, coating material and glidant. Our mechanochemical dry powder coating method using the mechanofusion system is a simple and promising means of solventless pharmaceutical coating.
This article is an introduction and general discussion regarding the use of Fisher-Tropsch wax in petroleum jelly applications. Traditionally, petroleum jelly is prepared from a blend of microwax, paraffin wax and mineral oil that are all derived from crude oil. Sasol Wax has successfully prepared a petroleum jelly based on predominantly to fully synthetic Fisher-Tropsch wax. Sasol Wax was awarded a patent P53898ZP00-29 November 11 for a predominantly to fully synthetic petroleum jelly based on Fisher-Tropsch wax blends. The benefits of Fisher-Tropsch wax discussed in this article include the absence of aromatic compounds and polycyclic aromatic compounds in Fisher-Tropsch wax as well as the sustainable production that is possible with Fisher-Tropsch wax, as opposed to paraffin wax that may be affected by the closure of group I Base Oil plants. This article will be the first in a series of articles from the same authors, and follow-up articles will include solid-state nuclear magnetic resonance and crystallization studies to determine the influence of predominantly synthetic waxes on petroleum jelly network structures compared with more traditional mineral oil-derived petroleum jellies, final product performance and stability of synthetic petroleum jelly used in, for example, personal care lotions or creams. The influence of oxygenated compounds and product safety and rheological properties (including primary skin feel upon application and secondary skin feel after application) of synthetic petroleum jellies compared with traditional mineral oil-derived petroleum jellies are discussed.
Rapid advancements in carbon-based fillers have enabled a new and more promising platform in the development of electromagnetic attenuation composites. Alignment of fillers in composites with specific structures and morphologies has been widely pursued to achieve high performance based on taking advantage of unique filler characteristics. In this work, few-layer graphene (FLG), obtained from direct exfoliation of graphite, was fabricated into paraffin wax to prepare FLG/wax composites and investigate their electromagnetic interference (EMI) shielding performance. The as-exfoliated FLG/wax samples have shown much improved EMI performance compared to the commercial graphite/wax ones. For further improvement of EMI shielding performance, split-press-merge approaches were applied to align the FLG fillers to achieve anisotropic characteristics in the plane perpendicular to the pressing direction. Much enhanced EMI shielding performance coupled with an improvement in absorption and reflection was observed in the post-alignment FLG/wax composites. An average interparticle distance model associated with improved electrically conducting interconnection and enlarged effective reflection regions with respect to enhanced reflection efficiency were discussed. The results suggest a platform and promising opportunities for preparing high-performance EMI shielding composites.
Infrared microspectroscopy is an emerging approach for disease analysis owing to its capability for in situ chemical characterization of pathological processes. Synchrotron-based infrared microspectroscopy (SR-IMS) provides ultra-high spatial resolution for profiling biochemical events associated with disease progression. Spectral alterations were observed in cultured oral cells derived from healthy, precancerous, primary, and metastatic cancers. An innovative wax-physisorption-based kinetic FTIR imaging method for the detection of oral precancer and cancer was demonstrated successfully. The approach is based on determining the residual amount of paraffin wax (C(25)H(52)) or beeswax (C(46)H(92)O(2)) on a sample surface after xylene washing. This amount is used as a signpost of the degree of physisorption that altered during malignant transformation. The results of linear discriminant analysis (LDA) of oral cell lines indicated that the methylene (CH(2)) and methyl group (CH(3)) stretching vibrations in the range of 3,000-2,800 cm(-1) have the highest accuracy rate (89.6 %) to discriminate the healthy keratinocytes (NHOK) from cancer cells. The results of wax-physisorption-based FTIR imaging showed a stronger physisorption with beeswax in oral precancerous and cancer cells as compared with that of NHOK, which showed a strong capability with paraffin wax. The infrared kinetic study of oral cavity tissue showed a consistency in the wax physisorption of the cell lines. On the basis of our findings, these results show the potential use of wax-physisorption-based kinetic FTIR imaging for the early screening of oral cancer lesions and the chemical changes during oral carcinogenesis.
Physico-chemical properties and efficacy of silk fibroin fabric coated with different waxes as wound dressing
- International journal of biological macromolecules
- Published almost 7 years ago
Silk fibroin (SF) has been widely used as a wound dressing material due to its suitable physical and biological characteristics. In this study, a non-adhesive wound dressing which applies to cover the wound surface as an absorbent pad that would absorb wound fluid while accelerate wound healing was developed. The modification of SF fabrics by wax coating was purposed to prepare the non-adhesive wound dressing that is required in order to minimize pain and risk of repeated injury. SF woven fabrics were coated with different types of waxes including shellac wax, beeswax, or carnauba wax. Physical and mechanical properties of the wax-coated SF fabrics were characterized. It was clearly observed that all waxes could be successfully coated on the SF fabrics, possibly due to the hydrophobic interactions between hydrophobic domains of SF and waxes. The wax coating improved tensile modulus and percentage of elongation of the SF fabrics due to the denser structure and the thicker fibers coated. The in vitro degradation study demonstrated that all wax-coated SF fabrics remained up to 90% of their original weights after 7 weeks of incubation in lysozyme solution under physiological conditions. The wax coating did not affect the degradation behavior of the SF fabrics. A peel test of the wax-coated SF fabrics was carried out in the partial- and full-thickness wounds of porcine skin in comparison to that of the commercial wound dressing. Any wax-coated SF fabrics were less adhesive than the control, as confirmed by less number of cells attached and less adhesive force. This might be that the wax-coated SF fabrics showed the hydrophobic property, allowing the loosely adherence to the hydrophilic wound surface. In addition, the in vivo biocompatibility test of the wax-coated SF fabrics was performed in Sprague-Dawley rats with subcutaneous model. The irritation scores indicated that the carnauba wax-coated SF fabric was not irritant while the shellac wax or beeswax-coated SF fabrics were slightly irritant, comparing with the commercial wound dressing. Therefore, SF fabrics coated with waxes, particularly carnauba wax, would be promising choices of non-adhesive wound dressing.
Today the high demand for electronics leads to massive production of waste, thus green materials based electronic devices are becoming more important for environmental protection and sustainability. The biomaterial based hydrogels are widely used in tissue engineering, but their uses in photonics are limited. In this study, silk fibroin protein in hydrogel form is explored as a bio-friendly alternative to conventional polymers for lens applications in light-emitting diodes. The concentration of silk fibroin protein and crosslinking agent had direct effects on optical properties of silk hydrogel. The spatial radiation intensity distribution was controlled via dome- and crater-type silk-hydrogel lenses. The hydrogel lens showed a light extraction efficiency over 0.95 on a warm white LED. The stability of silk hydrogel lens is enhanced approximately three-folds by using a biocompatible/biodegradable poly(ester-urethane) coating and more than three orders of magnitude by using an edible paraffin wax coating. Therefore, biomaterial lenses show promise for green optoelectronic applications.
As organisms develop, they first invest resources in survival and growth, but after reaching a certain condition they start to also invest in reproduction. Likewise, superorganisms, such as honey bee colonies, first invest in survival and growth, and later commit resources to reproduction once the number of workers in the colony surpasses a reproductive threshold. The first form of reproductive investment for a honey bee colony is the building of beeswax comb made of special large cells used for rearing males (drones). How do the workers sense that their colony is large enough to start building this ‘drone comb’? To address this question, we experimentally increased three possible cues of colony size - worker density, volatile pheromone concentration and nest temperature - and looked for effects on the bees' comb construction. Only the colonies that experienced increased worker density were stimulated to build a higher proportion of drone comb. We then monitored and quantified potential cues in small and large colonies, to determine which cues change with colony size. We found that workers in large colonies, relative to small ones, have increased contact rates, spend more time active and experience less variable worker density. Whereas unicellular and multicellular organisms use mainly chemical cues to sense their sizes, our results suggest that at least one superorganism, a honey bee colony, uses physical cues to sense its size and thus its developmental state.
The objective of this study was to develop functional nanostructured lipid carriers (NLCs) using beeswax (BW), propolis wax (PW) and pomegranate seed oil (PSO). NLCs were prepared by a melt emulsification-ultra sonication technique. The influences of solid lipid composition, surfactant blend concentration (2, 4, and 6% of formulation) and PSO content (10, 30 and 50% of total lipid phase) were investigated. Statistical evaluations revealed that the formulation variables had significant effects on physical properties of NLC. The developed nanocarriers presented particle sizes ranging from 71 to 366 nm, leading to excellent physical stability. The optimum formulations with minimum particle size and high zeta potential value were PW and BW + glycerol behenate samples, containing 10% oil and 6% surfactant. DSC and XRD studies indicated that the addition of oil to the lipid phase could disturb the crystalline order and form lattice defects. TEM observations exhibited spherical morphology of the NLCs.
Paraffin wax (PW) is widely used for smart thermo-regulation materials due to its good thermal performance. However, the leakage and low thermal conductivity of the PW suppress its application in the heat storage field. Accordingly, developing effective methods to address these issues is of great importance. In this study, we explored a facile approach to obtain PW-loaded core-sheath structured flexible nanofibers film via coaxial electrospinning technique. The PW as the core layer was successfully encapsulated by the sheath layer PMMA. The diameter of fiber core increased from 395 nm to 848 nm as the core solution speed rate increased from 0.1 ml/h to 0.5 ml/h. In addition, it can be seen that the higher core solution speed rate could lead to higher PW encapsulation efficiency according to the TEM results. The core-sheath nanofibers films, moreover, possessed the highest latent heat of 58.25 J/g and solidifying enthalpy of 56.49 J/g. Also, we found that after 200 thermal cycles, there was little change in latent heat, which demonstrated it is beneficial for the PW-loaded core-sheath structure to overcome the leakage issue and enhance thermal stability properties for the thermo-regulation film.
Propolis, a resinous substance collected by honeybees by mixing their saliva with plant sources, including tree bark and leaves and then mixed with secreted beeswax, possesses a variety of bioactivities. Whereas caffeic acid phenethyl ester (CAPE) has been recognized as a major bioactive ingredient in New Zealand propolis, Brazilian green propolis, on the other hand, possesses artepillin C (ARC). In this study, we report that, similar to CAPE, ARC docks into and abrogates mortalin-p53 complexes, causing the activation of p53 and the growth arrest of cancer cells. Cell viability assays using ARC and green propolis-supercritical extract (GPSE) revealed higher cytotoxicity in the latter, supported by nuclear translocation and the activation of p53. Furthermore, in vivo tumor suppression assays using nude mice, we found that GPSE and its conjugate with γ cyclodextrin (γCD) possessed more potent anticancer activity than purified ARC. GPSE‑γCD may thus be recommended as a natural, effective and economic anticancer amalgam.