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Marine Polysaccharides in Pharmaceutical Applications
Published in Se-Kwon Kim, Marine Biochemistry, 2023
Riyasree Paul, Sourav Kabiraj, Sreejan Manna, Sougata Jana
Agarose is extracted from the cell wall of red algae. The basic structural element of agarose is monosaccharide connected through repeating agarobiose units. It also contains galactose residue connected through the linkages of α-(1Ñ3) and β-(1Ñ4) (Hickson and Polson 1968). Agarose exhibits structural similarity with carrageenans except the L-conformation of unit A (α-(1Ñ3)) (Armisen 1995). Several pharmaceutical applications of agarose have been reported in developing hydrogels and nanoparticulate delivery systems (Khodadadi et al. 2020).
Molecular Approaches Towards the Isolation of Pediatric Cancer Predisposition Genes
Published in John T. Kemshead, Pediatric Tumors: Immunological and Molecular Markers, 2020
This ability to cover large distances in the genome depends on the activity of specific restriction enzymes which cut very infrequently in the human genome. Several such enzymes exist and are listed in Table 1. It will be noted that most of them have, within their recognition sequences, the CpG dinucleotide which, because the human genome is AT-rich, occur five times less frequently than would be expected. 99% of human CpG dinucleotides are methylated, a requirement for the action of the majority of restriction enzymes. The enzymes listed in Table 1, however, require unmethylated DNA as a substrate which only occurs in 1% of the genome. Digestion with these rare cutting enzymes generates DNA fragments which are 0.2 to 2 Mbp long. Conventional agarose gel methods, however, are only capable of separating DNA fragments up to 50 kb long. To cope with the larger fragments generated, pulse field gel electrophoresis (PFGE) has been developed. This work was pioneered by Cantor and colleagues122 working with yeast chromosomes, but the system has since been successfully adapted to separating human DNA. The details of this technique are discussed by van Ommen and Verkerk123 and Anand.124
Sensor-Enabled 3D Printed Tissue-Mimicking Phantoms: Application in Pre-Procedural Planning for Transcatheter Aortic Valve Replacement
Published in Ayman El-Baz, Jasjit S. Suri, Cardiovascular Imaging and Image Analysis, 2018
Kan Wang, Chuck Zhang, Ben Wang, Mani A Vannan, Zhen Qian
Agarose-based phantom is one of the most widely used substitutes for soft tissues due to its well-characterized performance and simple fabrication process. Mitchell et al. reported their study of agarose as a phantom material for NMR imaging in 1986 [12]. Agarose is derived from agar, a hydrophilic colloid that is extracted from algae. In this recipe, dry agarose is dissolved in a mixture of water and propanol. In later versions, other additives, such as evaporated milk [16] or glass beads [17] were added to tune attenuation or scattering properties. In 2001, Ramnarine et al. incorporated the agar-based technique into vascular phantoms in a European commission project [18]. In this material, water and glycerol were mixed with a high-strength agar. Other gradients were also used. Benzalkonium chloride was added to control microbial invasion. Al2O3 powder was added to control attenuation. SiC powder was added to tune backscatter. The high-strength agar was reported to provide superior structural rigidity compared with standard agarose-based materials and was well suited for vascular flow tests.
A click chemistry-based, free radical-initiated delivery system for the capture and release of payloads
Published in Drug Delivery, 2023
Emily T. DiMartini, Kelly Kyker-Snowman, David I. Shreiber
Agarose is a biostructural molecule that can readily be formed into beads for use as a cell-free tissue phantom for high-throughput studies. We generated free radicals through HRP-catalyzed reduction of H2O2 using 0–1.5 mM H2O2 and an acetylacetone mediator (Danielson et al., 2018). Although reported H2O2 concentrations at diseased sites are elevated relative to healthy tissues, in vivo concentrations remain in the micromolar range. We used a single bolus of free radicals at a higher concentration to model the continuous, lower radical levels in vivo (Gupta et al., 2012; Weinstain et al., 2014; Zhang et al., 2019). We found that the amount of payload captured within agar was directly dependent on the H2O2 concentration. This indicates that when more free radicals are present, increased crosslinking of the initial polymer network occurs, leading to a higher amount of payload captured. This is critical, as we expect that higher ROS levels at the disease site will initiate crosslinking and capture, whereas lower levels in healthy tissues will minimally couple the polymers and allow them to clear.
Effects of microwave ablation on cysts and cystic neoplasms with tissue-mimicking model: an ex vivo study
Published in International Journal of Hyperthermia, 2023
Agarose (Agarose G-10, Biowest, Spain) at a concentration of 4 g/200 ml was selected as the gelling agent for the preparation of a visualization and fixation matrix. The temperature of the agarose solution was maintained at 40–45 °C. A 1-ml syringe needle was used to puncture the fixed end of the bladder cavity, the initial urine was aspirated, and 0.9% sodium chloride was injected into the bladder. The liquid was maintained at a temperature of 37 °C. The volume of injected fluid was determined according to the maximum transverse diameter of the bladder (5.0 cm/60 ml). Then, ex vivo rabbit healthy bladder and VX2-implanted tumor bladder were immersed in agarose solution that had been cooled to 40–45 °C and kept intact in the solution. The gel fixation matrix was formed by leaving it at room temperature (23 °C) for approximately 40 min, which completed the development of cyst and cystic neoplasm mimic models (Figure 1(B)).
Experimental and computational evaluation of capacitive hyperthermia
Published in International Journal of Hyperthermia, 2022
Marcus Beck, Peter Wust, Eva Oberacker, Alexander Rattunde, Tom Päßler, Benjamin Chrzon, Paraskevi Danai Veltsista, Jacek Nadobny, Ruben Pellicer, Enrico Herz, Lukas Winter, Volker Budach, Sebastian Zschaeck, Pirus Ghadjar
A homogeneous phantom was produced according to the quality assurance guidelines for superficial hyperthermia [16]. First, a casting mold made of acrylic glass (width: 30 cm, depth: 30 cm, height: 16 cm) was manufactured (Figure 1.1(a)). The acrylic glass was previously prepared with drill holes required for insertion and fixation of catheters (1.6 mm diameter) for temperature measurements. 640 grams of Agarose powder (Sigma Aldrich) and 38.4 grams of sodium chloride were mixed with 15.5 liters of heated (70° celsius) demineralized water, followed by a heating period at a temperature of 85° celsius maintained for 10 min. Afterward, the agarose mixture was poured into the casting mold for hardening. The mixture of agarose, sodium chloride, and demineralized water was selected in accordance with the guidelines to manufacture a homogeneous 2/3 muscle equivalent phantom with the following properties: σ = 0.44–0.6 S/m, εr = 79, ρ = 969 kg/m3 at 13.56 MHz [16].