Gels

We have developed a novel three-dimensional (3D) cellular microarray platform to enable the rapid and efficient tracking of stem cell fate and quantification of specific stem cell markers. This platform consists of a miniaturized 3D cell culture array on a functionalized glass slide for spatially addressable high-throughput screening. A microarray spotter was used to deposit cells onto a modified glass surface to yield an array consisting of cells encapsulated in alginate gel spots with volumes as low as 60 nL. A method based on an immunofluorescence technique scaled down to function on a cellular microarray was also used to quantify specific cell marker protein levels in situ. Our results revealed that this platform is suitable for studying the expansion of mouse embryonic stem (ES) cells as they retain their pluripotent and undifferentiated state. We also examined neural commitment of mouse ES cells on the microarray and observed the generation of neuroectodermal precursor cells characterized by expression of the neural marker Sox-1, whose levels were also measured in situ using a GFP reporter system. In addition, the high-throughput capacity of the platform was tested using a dual-slide system that allowed rapid screening of the effects of tretinoin and fibroblast growth factor-4 (FGF-4) on the pluripotency of mouse ES cells. This high-throughput platform is a powerful new tool for investigating cellular mechanisms involved in stem cell expansion and differentiation and provides the basis for rapid identification of signals and conditions that can be used to direct cellular responses. Biotechnol. Bioeng. 2010; 106: 106–118. © 2010 Wiley Periodicals, Inc.

Yeast cells immobilized by entrapment in an insolubilized gelatin gel have been investigated with regard to their pattern of growth and respiratory activity. Mass-transfer resistance offered by the matrix and growth of the entrapped cells determine a gradient of nutrients throughout the gel which is responsible for both a lower specific growth rate of immobilized cells with respect to that of free ones, and a heterogeneous biomass distribution, with progressively increased cellular density from the inside to the outside of the matrix. The spatial organization of the growing cells leads to the formation of a biofilm perfectly adherent to the surface of the matrix. Measurements of the oxygen-uptake rate of the immobilized cells, after having been released from the matrix by trypsin digestion, and confocal microscopy of cells stained with Rhodamine 123 demonstrate the occurrence of a gradient of respiratory activity throughout the immobilized culture.

The aim of this work was the evaluation of conductivity assessments for the monitoring and controlling the release study process of chlorhexidine and lidocaine hydrochloride from the ionic polyacrylic gel, applying different temperatures. According to performed measurements of release, the chlorhexidine, characterized by very low water solubility, is observed in the acceptor compartment in the amount of 2.0-3.0% and its level depends of the temperature. The amount of well soluble lidocaine hydrochloride released in parallel conditions was between 60 and 70%. Beyond, the assessments confirm the presence of a specific bond between the chlorhexidine imine groups and polyacrylic acid carboxylic groups. Presented method may be applied in the prediction of release rates, before actual release analysis, and may assure better evaluation of the systems.

The goal of the current study was to explore the potential benefits of Acitretin (Act) nanovesicular gel as a prospective antipsoriatic topical delivery system counteracting the drug challenges in terms of its extremely low aqueous solubility, instability, skin irritation, and serious systemic adverse effects. Act-loaded niosomes were successfully developed, entirely characterized, and optimized. Further evaluation of the optimized formula was conducted regarding its stability and ex vivo cytotoxicity on different cell lines. The optimized niosomal vesicles were then incorporated in gel base matrix and investigated by sequential ex vivo (skin permeation and deposition) and in vivo (skin irritation and antipsoriatic activity using mouse tail model) experiments. The optimized Act-loaded niosomes (span 60:cholesterol molar ratio 1:1) were spherical in shape and exhibited the highest entrapment efficiency (90.32±3.80%) with appropriate nanosize and zeta potential of 369.73±45.45 nm and ...

Chronic wounds are characterized by a long inflammatory phase that hinders regenerative wound healing. The purpose of this prospective case series was to evaluate how a physiologically relevant concentration of an autologous platelet-rich plasma (PRP) gel affects initial wound healing trajectories of chronic, nonhealing wounds of various etiologies and in different care settings. Using convenience sampling methods, 49 patients (average age: 60.6 years, SD 14.7) with 65 nonhealing wounds (mean duration 47.8 weeks, range 3 to 260) at eight long-term acute care (LTAC) hospitals and three outpatient foot or wound clinics who were prescribed PRP gel for their nonhealing wound were enrolled. The majority of patients had low albumin, hematocrit, and/or hemoglobin levels. After wound assessments and measurements were obtained and the gel prepared, a skin barrier was applied to the periwound skin and the gel applied and protected with cover dressings. The most common wounds were pressure ulc...

This study evaluates the effect of subgingival irrigation with a 1% chlorhexidine collagen gel in periodontal pockets as an adjunct procedure to scaling and root planing (SRP). Thirty-seven sites with probing depth (PD) of 5-7 mm and BANA positive in 6 patients with chronic periodontal disease were selected. Sites were assigned to different treatment groups consisting of SRP only (group 1), SRP + irrigation with collagen gel (group 2), or SRP + irrigation with collagen gel containing 1% chlorhexidine (group 3). Subgingival irrigation was performed after initial SRP and at 7, 14 and 21 days. Clinical measurements including PD, plaque index (PI), gingival index (GI), gingival recession (GI), bleeding on probing (BOP) and clinical attachment level (CAL) were performed at the selected sites at baseline, 60 and 90 days and the BANA test was performed on plaque samples from the same sites at baseline and 90 days. There was an improvement in clinical parameters in all groups with a signifi...

Background: Blood-borne infection is an ever-present fear for medical professionals, espe-cially surgeons and operating room personnel. Safety is paramount, and the reliability and efficacy of surgical gloves are crucial, as gloves are the most important barriers protecting hospital ...

Ice crystal growth and microstructure of sugarsolutions prepared with stabilizers (carboxymethyl cellulose [CMC], xanthan gum, locust bean gum [LBG], and gelatin) with or without milk solids-nonfat (MSNF) after freezing in a scraped surface heat exchanger and temperature cycling (5 cycles from -6 degrees C to -20 degrees C) were studied. Ice crystal growth was calculated from brightfield microscopic images acquired from samples before and after cycling. Freeze-substitution and low-temperature embedding (LR-Gold resin) were sample preparation techniques utilized for structure analyses by light microscopy and transmission electron microscopy. Differential staining for carbohydrates and proteins allowed the identification of stabilizer gel-like structures in LBG, gelatin, and gelatin/MSNF solutions. In the absence of milk proteins, xanthan and LBG were the most effective at retarding recrystallization, while in their presence, only xanthan had an effect. Cryo-gelation of the LBG was ob...