Photonic crystals (PCs) are nanomaterials with photonic properties made up of periodically modulated dielectric materials that reflect light between a wavelength range located in the photonic band ...gap. Colloidal PCs (C-PC) have been proposed for several applications such as optical platforms for the formation of physical, chemical, and biological sensors based on a chromatic response to an external stimulus. In this work, a robust protocol for the elaboration of photonic crystals based on SiO2 particle (SP) deposition using the vertical lifting method was studied. A wide range of lifting speeds and particle suspension concentrations were investigated by evaluating the C-PC reflectance spectrum. Thinner and higher reflectance peaks were obtained with a decrease in the lifting speed and an increase in the SP concentrations up to certain values. Seven batches of twelve C-PCs employing a SP 3% suspension and a lifting speed of 0.28 µm/s were prepared to test the reproducibility of this method. Every C-PC fabricated in this assay has a wavelength peak in a range of 10 nm and a peak width lower than 90 nm. Inverse-opal polymeric films with a highly porous and interconnected morphology were obtained using the developed C-PC as a template. Overall, these results showed that reproducible colloidal crystals could be elaborated on a large scale with a simple apparatus in a short period, providing a step forward in the scale-up of the fabrication of photonic colloidal crystal and IO structures as those employed for the elaboration of photonic polymeric sensors.
Molecular imprinting has shown significant advances in the recognition and separation of small molecules. This technology has been proposed for different applications, including solid-phase ...extraction, stationary phases in HPLC, chemical sensing, drug-delivery systems, passive sampling, among others. However, imprinting of biological macromolecules with increased structural complexity is still challenging. In this work, CaCO
3
microparticles were synthesized using a precipitation method and employed as a novel support for the preparation of molecularly imprinted polymers (MIPs) towards a model protein (bovine serum albumin, BSA), through the polymerization of dopamine. Microparticles exhibited a rhombohedral morphology and a narrow size distribution (2.5 ± 0.4 µm). Reaction times showed to increase the polydopamine coating thickness, the MIP adsorption capacities, and the impression efficiency, reaching values of 5.1 nm, 50.2 ± 5.9 mg BSA/g sample, and 8.1 after 24 h, respectively. In addition, lower adsorption capacities were observed against proteins with similar physicochemical properties, such as ovalbumin (25.07 ± 2.5 mg/g) and casein (19.62 ± 7.01 mg/g). The adsorption kinetic assay indicated that MIPs present the highest BSA adsorption capacity after 1 h. In this regard, a methodology that offers a simple approach for the synthesis of materials designed for the specific recognition and separation of biological molecules is presented. The microparticles developed represent a potential use for protein separation in applications such as stationary phase in liquid chromatography.
Graphical abstract
Photonic crystals (PCs) are nanomaterials with photonic properties made up of periodically modulated dielectric materials that reflect light between a wavelength range located in the photonic band ...gap. Colloidal PCs (C-PC) have been proposed for several applications such as optical platforms for the formation of physical, chemical, and biological sensors based on a chromatic response to an external stimulus. In this work, a robust protocol for the elaboration of photonic crystals based on SiOsub.2 particle (SP) deposition using the vertical lifting method was studied. A wide range of lifting speeds and particle suspension concentrations were investigated by evaluating the C-PC reflectance spectrum. Thinner and higher reflectance peaks were obtained with a decrease in the lifting speed and an increase in the SP concentrations up to certain values. Seven batches of twelve C-PCs employing a SP 3% suspension and a lifting speed of 0.28 µm/s were prepared to test the reproducibility of this method. Every C-PC fabricated in this assay has a wavelength peak in a range of 10 nm and a peak width lower than 90 nm. Inverse-opal polymeric films with a highly porous and interconnected morphology were obtained using the developed C-PC as a template. Overall, these results showed that reproducible colloidal crystals could be elaborated on a large scale with a simple apparatus in a short period, providing a step forward in the scale-up of the fabrication of photonic colloidal crystal and IO structures as those employed for the elaboration of photonic polymeric sensors.
Photonic crystals (PCs) are nanomaterials with photonic properties made up of periodically modulated dielectric materials that reflect light between a wavelength range located in the photonic band ...gap. Colloidal PCs (C-PC) have been proposed for several applications such as optical platforms for the formation of physical, chemical, and biological sensors based on a chromatic response to an external stimulus. In this work, a robust protocol for the elaboration of photonic crystals based on SiO
particle (SP) deposition using the vertical lifting method was studied. A wide range of lifting speeds and particle suspension concentrations were investigated by evaluating the C-PC reflectance spectrum. Thinner and higher reflectance peaks were obtained with a decrease in the lifting speed and an increase in the SP concentrations up to certain values. Seven batches of twelve C-PCs employing a SP 3% suspension and a lifting speed of 0.28 µm/s were prepared to test the reproducibility of this method. Every C-PC fabricated in this assay has a wavelength peak in a range of 10 nm and a peak width lower than 90 nm. Inverse-opal polymeric films with a highly porous and interconnected morphology were obtained using the developed C-PC as a template. Overall, these results showed that reproducible colloidal crystals could be elaborated on a large scale with a simple apparatus in a short period, providing a step forward in the scale-up of the fabrication of photonic colloidal crystal and IO structures as those employed for the elaboration of photonic polymeric sensors.
Mesoporous silica particles (MSP) have received increasing interest for various applications because of their unique features such as controlled pore size, low density, high chemical and thermal ...stability, and high surface area. In this study, MSP was applied as an additive in water-based drilling fluids (WBMs). The effect of MSP on the rheological, thermal, filtration, and structural properties of WBMs was investigated. The results were compared with those of analogous fluids containing conventional nonporous silica particles (SSP). Rheological assays showed shear-thinning and viscoelastic behavior, which were more noticeable for fluids including MSP. It was observed that low concentrations of MSP (0.25 %wt) can achieve the same rheological properties as the fluids with higher SSP content (up to 0.5 %wt). The rheological properties of SSP-containing fluids were not significantly affected by the presence of NaCl or aging tests. The theoretical Herschel–Bulkley model represents the rheological behavior of WBMs. The MSP-based WBMs exhibited better filtration properties before aging. The microstructures of the WBMs were analyzed using Scanning Electron Microscopy (SEM). A homogeneous distribution of SSP in the WBMs was observed, while particle agglomeration was observed in WBMs containing MSP. In addition, surface interactions were studied to elucidate the interactions between particles and fluid constituents. The surface interaction, assessed through ζ-potential and FTIR analysis, revealed that the binding affinities of BT, PAC, and XGD with MSP were augmented compared to their individual values. Based on the experimental results, MSP constitutes a promising alternative as an additive for the design of WBMs.
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•The effect of silica particles type on water-based drilling fluids (WBMs) performance was investigated.•Lower concentrations of MSP were required to achieve the same rheological properties of the fluids containing SSP.•The physicochemical properties of SSP and MSP had a different effect on the performance of WBMs.•The surface interactions mainly governed the rheological properties of WBMs.
Purpose
The oral administration of drugs is usually the most convenient, economical, and preferred route for patients. Chitosan is a natural polymer that is biocompatible and possesses good ...mucoadhesion properties and has been proposed for various biomedical applications such as scaffolds in tissue engineering, wound dressing, and drug release systems. Fluoride is recognized for its ability to stimulate osteoblast differentiation and for its anticariogenic properties. When administered in low doses, it increases bone mass and reduces the risk of vertebral fractures in patients with osteoporosis. However, there is a debate about the potential negative effects of fluoride when applied in high doses or chronically. The objective of this study was to investigate the release of fluoride from chitosan microparticles loaded with fluoride and coated with two polymers, aimed at controlling its delivery.
Methods
Fluoride-loaded chitosan microparticles were developed using fluidized bed technology. Additionally, polyvinylpyrrolidone (PVP) and Eudragit
®
RS were applied to the particles using fluidized bed and dip-coating techniques. The obtained particles were then studied to obtain their release profiles. Infrared spectroscopy studies were conducted to analyze the chemical composition of the particles.
Results
The results showed that the coatings had a slight effect on the release of fluoride from the particles when applied using fluidized bed technology. Eudragit RS
®
30D coatings by immersion were found to be more effective in sustaining release of fluoride.
Conclusion
The study provides useful insights into the use of polymeric coatings in the development of chitosan-based oral delivery systems for the controlled release of a highly soluble API.
Chitosan - β-glycerophosphate hydrogels have been widely studied for biomedical applications in recent years. In the current study a Chitosan - β-glycerophosphate hydrogel was evaluated as a platform ...for sodium fluoride release in the gastrointestinal tract. For this purpose, microscopy observation, infrared spectroscopy, stability, rheology studies and in vitro release assays were carried out. The hydrogel was stable for at least 48 h when exposed to an aqueous media in a pH range from 4 to 7 and the release of sodium fluoride was controlled for more than 6 h.
In vivo studies were carried out in order to evaluate the oral administration of sodium fluoride using the hydrogel in comparison to a water solution. Fluoride pharmacokinetic was similar when the drug was administered with both formulations. Nevertheless, fluoride absorption was greater when the drug was given with the hydrogel, and further, drug-related side effects were absents. These results suggest that Chitosan - β-glycerophosphate hydrogel could be a good candidate for sustained release of fluoride in oral formulation.
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