25 research outputs found
Electrostatic Interaction on Loading of Therapeutic Peptide GLP‑1 into Porous Silicon Nanoparticles
Porous silicon (PSi) nanoparticles’
tunable properties are
facilitating their use at highly challenging medical tasks such as
peptide delivery. Because of many different mechanisms that are affecting
the interaction between the peptide and the particle, the drug incorporation
into the mesoporous delivery system is not straightforward. We have
studied the adsorption and loading of incretin hormone glucagon like
peptide 1 (GLP-1) on PSi nanoparticles. The results show that the
highest loading degree can be achieved in pH values near the isoelectric
point of peptide, and the phenomenon is independent of the surface’s
zeta potential. In order to study the interaction between the peptide
and the nanoparticle, we studied the adsorption with lower concentrations
and noticed that also non-Coulombic forces have a big role in adsorption
of GLP-1. Adsorption is effective and pH-independent especially on
low peptide concentrations and onto more hydrophobic nanoparticles.
Reversibility of adsorption was studied as a function of buffer pH.
When the loading is compared to the total mass of the formulation,
the loading degree is 29%, and during desorption experiments 25% is
released in 4 h and can be considered as a reversible loading degree.
Thus, the peptides adsorbed first seem to create irreversibly adsorbed
layer that facilitates reversible adsorption of following peptides
Optimization of a Wet Flue Gas Desulfurization Scrubber through Mathematical Modeling of Limestone Dissolution Experiments
Dissolution rates of two very pure
limestone samples were measured
experimentally by means of the pH-stat method under conditions where
mechanical stirring did not affect the rates considerably. The experimental
results were modeled mathematically by considering the surface areas
of the particles changing dynamically through the reaction; moreover,
a surface factor was introduced in order to account for the nonsphericity
of the particles. The surface areas were measured by means of gas
adsorption and by particle size distribution (laser diffraction).
Liquid-phase concentrations were measured by inductively coupled plasma
optical emission spectrometry, and surface compositions were measured
by X-ray spectroscopy. Furthermore, scanning electron microscope
images of the samples are presented. Subsequently, an optimization
model of a scrubber was developed by using the intrinsic parameters
of the samples, which were determined experimentally. The optimization
results indicate that up to 34–50% of the power required for
milling can be saved by milling to a coarser particle size than the
commonly used size of 44 μm, depending on the sample type. The
present model of the lab-scale experimental study and the optimization
model can be employed to estimate the actual impact that using different
types of raw material would have in the operation of a wet flue gas
desulfurization scrubber
Controlled Shape and Nucleation Switching of Interfacially Polymerizable Nanoassemblies by Methyl Substitution
Interfacial polymerization of uniform
template-free nanostructures
is very challenging since many factors play determinant roles in the
final structure of the resulting nanoassemblies. Here, we present
a single oxidative coupling method for the synthesis of different
nanoshapes by addition or substitution of a methyl group on aniline
monomers to freely alter the mechanism of monomer-to-polymer conversion.
Well-defined nanotubes, nanohollows, and solid nanospheres are obtained
from aniline, <i>N</i>-methylaniline, and 2-methylaniline
polymerizations, respectively. We found that the extent of hydrophobicity
and protonation under mild acidic conditions determines the monomers’
arrangement in micelle or droplet form, reactivity, and nucleation
mechanism. These can subsequently affect the final morphology through
a fusion process to form tubular structures, external flux of monomers
to form nanohollows, and intradroplet oxidation to form solid nanospheres.
Altered biological responses, such as cytocompatibility, redox response,
hemocompatibility, and cell proliferation, are also found to be dependent
on the position of the methyl group in the nanostructures
Cyclodextrin-Modified Porous Silicon Nanoparticles for Efficient Sustained Drug Delivery and Proliferation Inhibition of Breast Cancer Cells
Over the past decade, the potential
of polymeric structures has been investigated to overcome many limitations
related to nanosized drug carriers by modulating their toxicity, cellular
interactions, stability, and drug-release kinetics. In this study,
we have developed a successful nanocomposite consisting of undecylenic
acid modified thermally hydrocarbonized porous silicon nanoparticles
(UnTHCPSi NPs) loaded with an anticancer drug, sorafenib, and surface-conjugated
with heptakis(6-amino-6-deoxy)-β-cyclodextrin (HABCD) to show
the impact of the surface polymeric functionalization on the physical
and biological properties of the drug-loaded nanoparticles. Cytocompatibility
studies showed that the UnTHCPSi–HABCD NPs were not toxic to
breast cancer cells. HABCD also enhanced the suspensibility and both
the colloidal and plasma stabilities of the UnTHCPSi NPs. UnTHCPSi–HABCD
NPs showed a significantly increased interaction with breast cancer
cells compared to bare NPs and also sustained the drug release. Furthermore,
the sorafenib-loaded UnTHCPSi–HABCD NPs efficiently inhibited
cell proliferation of the breast cancer cells
Selective Optical Response of Hydrolytically Stable Stratified Si Rugate Mirrors to Liquid Infiltration
Stratified optical filters with distinct spectral features and layered surface chemistry were prepared on silicon substrates with stepwise anodic porosification and thermal carbonization. The use of differing parameters for successive carbonization treatments enabled the production of hydrolytically stable porous silicon-based layered optical structures where the adsorption of water to the lower layer is inhibited. This enables selective shifting of reflectance bands by means of liquid infiltration. The merit of using thermal carbonization for creating layered functionality was demonstrated by comparing the hydrolytic stability resulting from this approach to other surface chemistries available for Si. The functionality of the stratified optical structures was demonstrated under water and ethanol infiltration, and changes in the adsorption properties after 9 months of storage were evaluated. The changes observed in the structure were explained using simulations based on the transfer matrix method and the Bruggeman effective medium approximation. Scanning electron microscopy was used for imaging the morphology of the porous structure. Finally, the adaptability of the method for preparing complex structures was demonstrated by stacking superimposed rugate structures with several reflective bands
Controlled Dissolution of Griseofulvin Solid Dispersions from Electrosprayed Enteric Polymer Micromatrix Particles: Physicochemical Characterization and <i>in Vitro</i> Evaluation
The oral bioavailability
of a poorly water-soluble
drug is often inadequate for the desired therapeutic effect. The bioavailability
can be improved by enhancing the physicochemical properties
of the drug (e.g., dissolution rate, permeation across the gastrointestinal
tract). Other approach include shielding the drug from the gastric
metabolism and targeted drug release to obtain optimal drug absorption.
In this study, a poorly water-soluble model drug, griseofulvin,
was encapsulated as disordered solid dispersions into Eudragit L 100-55
enteric polymer micromatrix particles, which were produced by
electrospraying. Similar micromatrix particles were also
produced with griseofulvin-loaded thermally oxidized mesoporous
silicon (TOPSi) nanoparticles dispersed to the polymer micromatrices.
The <i>in vitro</i> drug dissolution at pH 1.2 and 6.8,
and permeation at pH 7.4 across Caco-2/HT29 cell monolayers from the
micromatrix particles, were investigated. The micromatrix
particles were found to be gastro-resistant, while at pH 6.8 the griseofulvin
was released very rapidly in a fast-dissolving form. Compared to free
griseofulvin, the permeability of encapsulated griseofulvin
across the intestinal cell monolayers was greatly improved, particularly
for the TOPSi-doped micromatrix particles. The griseofulvin
solid dispersions were stable during storage for 6 months at accelerated
conditions. Overall, the method developed here could prove to be a
useful oral drug delivery solution for improving the bioavailability
of poorly water-soluble or otherwise problematic drugs
Additional file 1: of Size, Stability, and Porosity of Mesoporous Nanoparticles Characterized with Light Scattering
Contains following supplementary materials: fabrication of porous silicon nanoparticles, fabrication of silica nanoparticles, summary of silica nanoparticles' preparation conditions, summary of log-normal fitting results, absorbance of used nanoparticles, nitrogen sorption isotherms, additional TEM graphs from silica nanoparticles, fractal dimension analysis for SLS results and Kratky plots, all the studied correlations and measured zeta potential distributions. (DOCX 11779 kb
Versatile Cellulose-Based Carbon Aerogel for the Removal of Both Cationic and Anionic Metal Contaminants from Water
Hydrothermal carbonization of cellulose
in the presence of the globular protein ovalbumin leads to the formation
of nitrogen-doped carbon aerogel with a fibrillar continuous carbon
network. The protein plays here a double role: (i) a natural source
of nitrogen functionalities (2.1 wt %) and (ii) structural directing
agent (<i>S</i><sub>BET</sub> = 38 m<sup>2</sup>/g). The
applicability in wastewater treatment, namely, for heavy metal removal,
was examined through adsorption of Cr(VI) and Pb(II) ion solely and
in a mixed bicomponent aqueous solutions. This cellulose-based carbogel
shows an enhanced ability to remove both Cr(VI) (∼68 mg/g)
and Pb(II) (∼240 mg/g) from the targeted solutions in comparison
to other carbon materials reported in the literature. The presence
of competing ions showed little effect on the adsorption efficiency
toward Cr(VI) and Pb(II)
Platelet Lysate-Modified Porous Silicon Microparticles for Enhanced Cell Proliferation in Wound Healing Applications
The
new frontier in the treatment of chronic nonhealing wounds is the
use of micro- and nanoparticles to deliver drugs or growth factors
into the wound. Here, we used platelet lysate (PL), a hemoderivative
of platelets, consisting of a multifactorial cocktail of growth factors,
to modify porous silicon (PSi) microparticles and assessed both <i>in vitro</i> and <i>ex vivo</i> the properties of
the developed microsystem. PL-modified PSi was assessed for its potential
to induce proliferation of fibroblasts. The wound closure-promoting
properties of the microsystem were then assessed in an <i>in
vitro</i> wound healing assay. Finally, the PL-modified PSi microparticles
were evaluated in an <i>ex vivo</i> experiment over human
skin. It was shown that PL-modified PSi microparticles were cytocompatible
and enhanced the cell proliferation in different experimental settings.
In addition, this microsystem promoted the closure of the gap between
the fibroblast cells in the wound healing assay, in periods of time
comparable with the positive control, and induced a proliferation
and regeneration process onto the human skin in an <i>ex vivo</i> experiment. Overall, our results show that PL-modified PSi microparticles
are suitable microsystems for further development toward applications
in the treatment of chronic nonhealing wounds