Search results for "freeze-drying"

Influence of freezing temperatures prior to freeze-drying on viability of yeasts and lactic acid bacteria isolated from wine

2017

Aims To determine the effect of three different freezing temperatures on post-freeze-drying survival rates of wine yeasts and lactic acid bacteria (LAB). To know if a similar freeze-drying protocol can be used for both micro-organisms. Methods and Results Cells from liquid culture media were recovered and concentrated in appropriate lyoprotectants. Aliquots of each strain were frozen at −20, −80 and −196°C before vacuum drying. Viable cell counts were done before freezing and after freeze-drying. Survival rates were calculated. Freezing temperatures differently affected yeast and bacteria survival. The highest survival rates were obtained at −20 and −80°C for yeasts, but at −196°C for LAB. …

Solid nanoemulsion as antigen and immunopotentiator carrier for transcutaneous immunization

2015

Imiquimod, a toll-like receptor 7 (TLR7) agonist, is an active pharmaceutical ingredient (API) established for the topical treatment of several dermal cancerous and precancerous skin lesions. Within this work, the immunostimulatory effect of imiquimod is further exploited in a transcutaneous immunization (TCI) approach based on a solid nanoemulsion (SN) formulation. SN contains a combination of imiquimod with the model peptide antigen SIINFEKL as a novel approach to omit needle and syringe and optimize dermal antigen administration. Excipients including sucrose fatty acid esters and the pharmaceutically acceptable oils MCT (middle chain triglycerides), avocado oil, jojoba wax and squalene a…

Hyaluronic acid and alpha-elastin based hydrogel for three dimensional culture of vascular endothelial cells

2018

Abstract The aim of this work was to demonstrate that employing a copolymer of hyaluronic acid and α-elastin (HA-EDA-g-α-elastin) is possible to produce a scaffold able to support the adhesion and growth of human vascular endothelial cells (HUVEC) thanks to its ability to incorporate and control the diffusion of vascular endothelial growth factor (VEGF). HA-EDA-g-α-elastin was crosslinked with low molecular weight hyaluronic acid (HALMW) to obtain a hydrogel that gives rise to the formation of three dimensional sponge after the freeze drying process. The physicochemical features the obtained material along with its ability to act as a support for the three dimensional culture of endothelial…

Keyhole limpet haemocyanin: negative staining in the presence of trehalose

1995

Abstract Samples of unpurified and purified haemocyanin from the giant keyhole limpet Megathura crenulata have been studied by transmission electron microscopy (TEM) using mixtures of trehalose with the negative stains, uranyl acetate and ammonium molybdate. Trehalose is a known protein preservative during air and freeze drying, UV irradiation and high temperatures, and therefore offers the possibility of protecting proteins during the drying of negatively-stained specimens and their subsequent electron microscopical study. Evidence is presented that trehalose possesses satisfactory stability within the electron beam during conventional room temperature, negative-staining studies. The combi…

Dissolution enhancement and in vitro performance of clarithromycin nanocrystals produced by precipitation–lyophilization–homogenization method

2014

The gastroduodenal diseases caused by Helicobacter pylori were commonly treated with antibiotic clarithromycin as a standard regimen. According to the poorly water-soluble of clarithromycin, the nanocrystal formulation was prepared. The aim of this study was to investigate an enhancement effect of clarithromycin nanocrystals produced by precipitation-lyophilization-homogenization (PLH) method on the saturation solubility, dissolution velocity, antibiotic activity, permeability through the gastric mucus and cellular permeability. Poloxamer 407 and sodium lauryl sulfate (SLS) were chosen as combined stabilizers in the nanocrystal system. The obtained clarithromycin nanocrystals were identifie…

Spray Freeze Dried Lyospheres® for Nasal Administration of Insulin

2021

Pharmacologically active macromolecules, such as peptides, are still a major challenge in terms of designing a delivery system for their transport across absorption barriers and at the same time provide sufficiently high long-term stability. Spray freeze dried (SFD) lyospheres® are proposed here as an alternative for the preparation of fast dissolving porous particles for nasal administration of insulin. Insulin solutions containing mannitol and polyvinylpyrrolidone complemented with permeation enhancing excipients (sodium taurocholate or cyclodextrins) were sprayed into a cooled spray tower, followed by vacuum freeze drying. Final porous particles were highly spherical and mean diameters r…

Superior Antibacterial Activity of Integral Lemon Pectin Extracted via Hydrodynamic Cavitation

2020

Abstract Pectin extracted via hydrodynamic cavitation in water only from waste lemon peel and further isolated via freeze drying displays significant antibacterial activity against Staphylococcus aureus, a Gram positive pathogen which easily contaminates food. The antibacterial effect of the new IntegroPectin is largely superior to that of commercial citrus pectin, opening the way to advanced applications of a new bioproduct now obtainable in large amounts and at low cost from citrus juice industry's waste.

Flame-burned stainless steel wire spheres as carriers ofZymomonas mobilis cells and extracellular levansucrase

1999

In the present work, the use of flame-burned WS as carriers of Z. mobilis and extracellular levansucrase and the effect of the cell fixation method by dehydration on system productivity were investigated. Lyophilization and convective drying of Z. mobilis biomass at 30°C to a moisture content of 10–14% gave the best results for the repeated batch fermentations of a sucrose medium to obtain levan and ethanol. Significant correlation between the product formation and the concentration of free cells in the fermentation medium was established. Clearly, the cells were weakly bound to the newly generated WS and were washed out into the medium during fermentation. Here the hypothesis is presented …

The impact of pulsed electric fields on quality parameters of freeze‐dried red beets and pineapples

2020

EPR Studies of Oxidation of Iron and Free Radicals Formation after Dessication of Oxyhemoglobin by Freeze-Drying and Spray-Drying

1992

Dans les Centres de Transfusion Sanguine, les hematies a peremption sont inutilisables. Elles peuvente transformees en solution d’hemoglobine en vue d’une utilisation potentielle pour transfuser, mais cela suppose, pour ce type de produit sanguin que les problemes de conservation resultant de l’oxydation de Fe(II) de I’heme soient resolus. Pour minimiser ce phenomene, on a voulu dessecher des preparations d’hemoglobines seules ou en presence de protecteur par differentes techniques a caractere industriel en vue d’etudier les produits formes au cours de ces traitements de dessiccation.