Ultrasonic can be used in chemistry to increase reaction rates and product yields. Most of the effect of ultrasound on chemical reactions is due to cavitation: the formation and collapse of small gas bubbles in a solvent. In this review, we first provide an overview of the physical background of cavitation and discuss its dependence on factors such as acoustic intensity and frequency, solvent and temperature. The effect of ultrasound on chemical reactions is considered for both homogeneous reactions and heterogeneous liquid-solid systems. The first area is mainly illustrated by discussing the effect of ultrasound on polymerization and depolymerization reactions, and the second area is illustrated by selected examples in organic synthesis. The tendency for sonication to alter the reaction mechanism in favor of a homolytic (rather than a heterolytic) pathway is also briefly discussed. A specific preference for a particular path under sonochemical conditions, as distinct from the path under mechanical agitation, is termed “sonochemical switching”. Ultrasonic equipment for laboratory-scale experiments is compared and some practical “tips and pitfalls” are given.
Sonication and Lysis of Cells
Ultrasonic sonochemical equipment is primarily used for sample preparation and production. These areas include, inter alia, the homogenization, emulsification and suspension of various substances, as well as the acceleration of chemical reactions, cell disruption and extraction of cell contents. The selective destruction of certain substances using ultrasonic sonochemical equipment can shorten tedious preparation processes and increase the yield of many reactions. A comparison with mechanical processing equipment such as planetary ball mills, rotor/stators or gap homogenizers shows that ultrasonic sonochemical equipment works with higher efficiency and in particular makes reproducible results possible. The trend in analysis is toward smaller sample sizes and the use of fewer chemicals. For example, in recent years, the use of ultrasonic sonochemical equipment has become critical, as even the smallest sample volumes need to be processed quickly, economically, and reproducibly.
Destruction of cells and microorganisms
In modern laboratories, ultrasonic sonochemical equipment is used to disrupt cell walls to extract cellular contents, such as proteins, without damaging them. A portion of the energy introduced into the cell suspension is converted into heat by friction. To avoid thermal damage to the cellular contents, samples were either periodically intermittently sonicated during sonication or cooled in a cooling vessel. The rosette pool enables uniform sonication of microorganisms as the ultrasonic energy forces the sample to circulate repeatedly under the probe and throughout the sidearm. Placed in an ice bath, the contents are effectively cooled due to the enlarged glass surface.
The disruption of the cell membrane depends largely on the elasticity of the cell. Cellular components, such as mitochondria or cytoplasm, can be partially disrupted by varying the input ultrasonic energy and extracted power. For particularly drug-resistant bacteria (e.g. streptococci), fungi, spores, yeast or tissue samples, direct destruction at very high ultrasound amplitudes can be carried out by the microtips, which can deliver very large energy inputs to the smallest sample volumes middle.
Foaming and splashing in the container is a bigger problem when using microliter volumes. Loss of valuable sample material may result. Therefore, power regulation is very important. Only a small power or small amplitude is required to disrupt cells with unstable walls. For continuous mass dissolution, special flow vessels made of glass or stainless steel with an ultrasound chamber are used to treat each particle of the suspension with equal intensity. Thermal damage to the cell contents can be ruled out if the vessel is additionally equipped with a cooling jacket. In order to avoid contamination by foreign particles – eg erosion particles of the probe – indirect sonication is preferably performed in a cup booster or cup horn. This method achieves uniform strength and cooling.
Applications in Biochemistry and Medicine:
1. Disruption of Tissue Culture
Subcellular components and viruses are destroyed without any damage.
2. Paternity test
Rapid extraction of matrix-free hemolysate from EDTA blood of the putative father for paternity testing (reduces preparation time by approximately 30 minutes).
3. Urology
Biofilm analysis of sperm composition.
4. Genetic research
DNA extraction from human material.
5. Liposome Preparation
Disintegration of MLVs (multilamellar vesicles) using ultrasound (20 kHz) is the main method for producing SLVs (unilamellar vesicles).
6. Smallpox vaccine treatment
Prepare an evenly distributed infection solution.
Post time:Apr-18-2023