lithium-chloride and formic-acid

Gellan gum gels have been proposed as tissue- and water-mimicking materials (phantoms) applied in medical imaging and radiotherapy dosimetry. Phantoms often require ionic additives to induce desirable electrical conductivity, resistance to biological spoilage, and radical scavenging properties. However, gellan gum is strongly crosslinked by the typically used sodium salts, forming difficult-to-work with gels with reduced optical clarity. Herein we investigated lithium and tetramethylammonium chloride to induce the required electrical conductivity while maintaining optical clarity; lithium formate and methylparaben were used as a radical scavenger and antimicrobial additive, respectively. Using a multifactorial design of experiments, we studied and modeled the electrical and mechanical properties and liquid expulsion (syneresis) properties of the gels. Finally, by the addition of a radiation-sensitive tetrazolium salt, dosimeters with favorable properties were produced. The results described herein may be used to prepare tissue phantoms and dosimeters with tuned electrical, mechanical, and dosimetric properties.

Topics: Electric Conductivity; Formates; Gels; Lithium Chloride; Mechanical Phenomena; Parabens; Phantoms, Imaging; Polysaccharides, Bacterial; Quaternary Ammonium Compounds; Radiation Dosimeters; Radiometry; Temperature; Water

Topics: Binding Sites; Enterobacter aerogenes; Enzyme Activation; Enzyme Activators; Formates; Hydrogen-Ion Concentration; Lithium Chloride; Models, Molecular; Osmolar Concentration; Potassium Chloride; Sodium Acetate; Sodium Chloride; Urease

Quality data collection for macromolecular cryocrystallography requires suppressing the formation of crystalline or microcrystalline ice that may result from flash-freezing crystals. Described here is the use of lithium formate, lithium chloride and other highly soluble salts for forming ice-ring-free aqueous glasses upon cooling from ambient temperature to 100 K. These cryosalts are a new class of cryoprotectants that are shown to be effective with a variety of commonly used crystallization solutions and with proteins crystallized under different conditions. The influence of cryosalts on crystal mosaicity and diffraction resolution is comparable with or superior to traditional organic cryoprotectants.

Topics: Cryoprotective Agents; Crystallography, X-Ray; Formates; Freezing; Ice; Lithium Chloride; Macromolecular Substances; Muramidase; Ribonucleases; Salts