232 research outputs found
Effects of ionizing radiation sterilization on microparticulate drug delivery systems based on poly-alfa-hydroxyacids: an overview.
Ionizing radiation treatment is particularly advantageous as a sterilization technique for polymeric drug delivery systems. In recent years
several authors have investigated this topic with interesting and sometimes controversial results. This overview was aimed at gathering and critically
discussing the studies performed on the effect of ionizing radiation sterilization on microparticulate drug delivery systems made of poly-α-
hydroxyacids. The results reported in the literature showed that ionizing radiation always led to a decrease in poly-α-hydroxyacids molecular
weight. This effect was strictly related to irradiation dose, irradiation conditions, and depended on the starting polymer molecular weight. The
presence of a drug and/or an additive inside the polymeric micromatrix could affect polymer behavior upon irradiation and consequently drug
release behavior. Electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) proved to be useful techniques to
elucidate the radiolytic mechanisms and the drug /polymer interaction upon irradiation
An injectable in situ forming composite gel to guide bone regeneration: Design and development of technology platform
Volumetric expression of palynological spectra for nutritional studies
When pollen is studied from nutritional point of view, it would be desirable to correct its raw palynological spectrum in order to express the mass contribution of each pollen type. Different approaches applied for this correction through volumetric coefficients are discussed, and a simple and reliable procedure is proposed
High efficiency vibrational technology (HEVT) for cell encapsulation in polymeric microcapsules
Poly(methyl-methacrylate) (PMMA) is a biocompatible and non-biodegradable polymer widely used as biomedical material. PMMA microcapsules with suitable dimension and porosity range are proposed to encapsulate live cells useful for tissue regeneration purposes. The aim of this work was to evaluate the feasibility of producing cell-loaded PMMA microcapsules through âhigh effciency vibrational technologyâ (HEVT). Preliminary studies were conducted to set up the process parameters for PMMA microcapsules production and human dermal fibroblast, used as cell model, were encapsulated in shell/core microcapsules. Microcapsules morphometric analysis through optical microscope and scanning electron microscopy highlighted that uniform microcapsules of 1.2 mm with circular surface pores were obtained by HEVT. Best process conditions used were as follows: frequency of 200 Hz, voltage of 750 V, flow rate of core solution of 10 mL/min, and flow rate of shell solution of 0.5 bar. Microcapsule membrane allowed permeation of molecules with low and medium molecular weight up to 5900 Da and prevented diffusion of high molecular weight molecules (11,000 Da). The yield of the process was about 50% and cell encapsulation efficiency was 27% on total amount. The cell survived and growth up to 72 h incubation in simulated physiologic medium was observed
Electrospun tubular vascular grafts to replace damaged peripheral arteries: A preliminary formulation study
Polymeric tubular vascular grafts represent a likely alternative to autologous vascular grafts for treating peripheral
artery occlusive disease. This preliminary research study applied cutting-edge electrospinning technique
for manufacturing prototypes with diameter †6 mm and based on biocompatible and biodegradable polymers
such as polylactide-polycaprolactone, polylactide-co-glycolide and polyhydroxyethylmethacrylate combined in
different design approaches (layering and blending). Samples were characterized about fiber morphology,
diameter, size distribution, porosity, fluid uptake capability, and mechanical properties. Biocompatibility and
cell interaction were evaluated by in vitro test. Goal of this preliminary study was to discriminate among the
prototypes and select which composition and design approach could better suit tissue regeneration purposes.
Results showed that electrospinning technique is suitable to obtain grafts with a diameter < 6 mm and thickness
between 140 ± 7â175 ± 4 ÎŒm. Scanning electron microscopy analysis showed fibers with suitable micrometric
diameters and pore size between 5 and 35 ÎŒm. polyhydroxyethylmethacrylate provided high hydrophilicity (â
100âŠ) and optimal cell short term proliferation (cell viability â 160%) in accordance with maximum fluid uptake
ability (300â350%). Moreover, addition of polyhydroxyethylmethacrylate lowered suture retention strength at
value < 1 N. Prototypes obtaining combining polylactide-co-glycolide and polylactide-coglycolide/ polyhydroxyethylmethacrylate
with polylactide-polycaprolactone in a bilayered structure showed optimal mechanical
behavior resembling native bovine vessel
The microfluidic technique and the manufacturing of polysaccharide nanoparticles
Themicrofluidic technique has emerged as a promising tool to accelerate the clinical translation of nanoparticles, and its application affects several aspects, such as the production of nanoparticles and the in vitro characterization in the microenvironment, mimicking in vivo conditions. This review covers the general aspects of the microfluidic technique and its application in several fields, such as the synthesis, recovering, and samples analysis of nanoparticles, and in vitro characterization and their in vivo application. Among these, advantages in the production of polymeric nanoparticles in a well-controlled, reproducible, and high-throughput manner have been highlighted, and detailed descriptions of microfluidic devices broadly used for the synthesis of polysaccharide nanoparticles have been provided. These nanoparticulate systems have drawn attention as drug delivery vehicles over many years; nevertheless, their synthesis using themicrofluidic technique is still largely unexplored. This review deals with the use of the microfluidic technique for the synthesis of polysaccharide nanoparticles; evaluating features of the most studied polysaccharide drug carriers, such as chitosan, hyaluronic acid, and alginate polymers. The critical assessment of the most recent research published in literature allows us to assume that microfluidics will play an important role in the discovery and clinical translation
of nanoplatforms
Diaminobenzidine photoconversion is a suitable tool for tracking the intracellular location of fluorescently labelled nanoparticles at transmission electron microscopy.
Chitosan-based nanoparticles (NPs) deserve particular attention as suitable drug carriers in the field of pharmaceutics, since they are able to protect the encapsulated drugs and/or improve their efficacy by making them able to cross biological barriers (such as the blood-brain barrier) and reach their intracellular target sites. Understanding the intracellular location of NPs is crucial for designing drug delivery strategies. In this study, fluorescently-labelled chitosan NPs were administered in vitro to a neuronal cell line, and diaminobenzidine (DAB) photoconversion was applied to correlate fluorescence and transmission electron microscopy to precisely describe the NPs intracellular fate. This technique allowed to demonstrate that chitosan NPs easily enter neuronal cells, predominantly by endocytosis; they were found both inside membrane-bounded vesicles and free in the cytosol, and were observed to accumulate around the cell nucleus
An improved model of the <i>Trypanosoma brucei</i> CTP synthetase glutaminase domain-acivicin complex
Evolution of Noninvasive Mechanical Ventilation Use: A Cohort Study Among Italian PICUs
To assess how clinical practice of noninvasive ventilation has evolved in the Italian PICUs
- âŠ