{"id":212,"date":"2020-12-08T21:37:32","date_gmt":"2020-12-09T02:37:32","guid":{"rendered":"https:\/\/www.cd-bioparticles.com\/blog\/?p=212"},"modified":"2020-12-08T21:37:32","modified_gmt":"2020-12-09T02:37:32","slug":"a-new-hybrid-technique-enabling-nanoparticle-separation","status":"publish","type":"post","link":"https:\/\/www.cd-bioparticles.com\/blog\/nanoparticles\/a-new-hybrid-technique-enabling-nanoparticle-separation\/","title":{"rendered":"A New Hybrid Technique Enabling Nanoparticle Separation"},"content":{"rendered":"\n
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With\nthe rapid development of nanotechnology, nanoparticles have been mass-produced\nand widely used in daily life. Continuous separation of nanoparticles plays a\nvital role in a wide range of research fields, from fundamental nanoscience to\nbiological and environmental applications, including circulating tumor cell\nanalysis, exosome detection, cargo loading efficiency and drug delivery,\nhazardous material removal, quantum dot production, and biosensor materials.\nHowever, due to the small size of nanoparticles, it is difficult to achieve\nhigh separation performance, efficiency, or even high-throughput. Therefore,\nthe separation of nanoparticles with high purity and high resolution is still\nan arduous task. In the research and production of nanomaterials, it is urgent\nto obtain nanoparticles with certain particle size, morphology, and structure\nby appropriate separation methods. Here we list several commonly used\ntechnologies for nanoparticle separation.<\/p>\n\n\n\n

Field\nflow fractionation<\/p>\n\n\n\n

The\nfield flow fractionation (FFF) was first invented by Giddings in 1966 and has\nbecome an important method for the separation of nanoparticles. FFF is a method\nthat applies “field” to a suspension or solution in a long and narrow\ntunnel, acts vertically (or from other angles) in the direction of the mobile phase,\nand uses different mobility under the action of “field” to achieve\nthe purpose of separation. This “field” can be the asymmetric flow\nfield of a semi-permeable membrane, or a centrifugal field, gravity field,\nthermal field, electric field, and magnetic field. For example, under the\naction of centrifugal force, nanoparticles can be separated according to\ndifferent sizes and densities. It has the advantages of a wide range of samples\nand high separation efficiency. This method can also be used to separate or\ndetect nanoparticles in combination with other instruments such as dynamic\nlight scatterers.<\/p>\n\n\n\n

FFF is\nsuitable for the detection and separation of nanoparticles in complex\nsubstrates such as atmosphere, tap water, sewage, surface water, sediment,\nsediment, and biological samples. According to the difference of sample\ndiffusion coefficient, FFF can achieve continuous, high sensitivity and high\naccuracy separation, and complete the determination of nanoparticle size\ndistribution at the same time. The deficiency of FFF is that the sample is easy\nto lose, and the pH value and ionic strength of the sample will also be\nchanged.<\/p>\n\n\n\n

Ultracentrifugation<\/p>\n\n\n\n

Ultracentrifugation\nincludes gradient ultracentrifugation based on density, viscosity, and\nvelocity. Different methods can be selected according to the size of target\nnanoparticles. Density gradient ultracentrifugation is a separation method in\nwhich samples are added to inert gradient media for sedimentation, and\nnanoparticles of different sizes are assigned to specific positions to form\ndifferent zones. This is an extensive, non-destructive, and scalable separation\nmethod. Density gradient ultracentrifugation has been successfully applied to\nthe separation of gold nanoparticles and biological macromolecules with\ndifferent chemical properties, structures, and sizes.<\/p>\n\n\n\n

Ultracentrifugation\ncan separate and enrich nanoparticles by using different properties such as\nweight and density and can purify chemically modified nanoparticles and\nseparate nanoparticles with different morphologies, sizes, or aggregations.\nMeanwhile, it has the advantage of less sample loss and has been widely used in\nthe separation of gold nanoparticles and quantum dots.<\/p>\n\n\n\n

Membrane\nseparation <\/p>\n\n\n\n

Generally\nspeaking, the membrane separation method is to retain the nanoparticles of\ndifferent sizes through the filtration of the membrane, so as to achieve the\npurpose of separation. The ultrafiltration process is a pressure-driven\nseparation method, which has the characteristics of fast separation speed and a\nwide range of applications and can reach the industrial scale. Compared with\nresin chromatography, membrane separation is more simple and efficient, easier\nto realize laboratory and industrial applications, and promotes the innovation\nof hemodialysis equipment.<\/p>\n\n\n\n

The\nthickness, pore size, hydrophobicity, and internal surface area of the membrane\nare important factors affecting the separation effect and separation rate. The\nhigher surface area will lead to the retention, loss, and blockage of the\nsample, and the thicker membrane will make the transport speed in the\npurification process too slow.<\/p>\n\n\n\n

Chromatography\nseparation<\/p>\n\n\n\n

The\nmembrane separation method is suitable for the separation of high concentration\nnanoparticles, while for low concentration nanoparticles, the chromatography\nseparation method has better advantages. The characteristic of chromatography\nseparation is that the sample can be separated and quantitatively detected at\nthe same time. Due to the hydrodynamic and electrophoretic properties of\nnanoparticles, the structural changes of nanoparticles before and after surface\nmodification can be detected by chromatography. The commonly used\nchromatography separation methods include high-performance liquid\nchromatography, size exclusion chromatography, capillary electrochromatography,\nand so on. The chromatographic stationary phase, mobile phase, and column can\nbe selected according to different separation objects and purposes.<\/p>\n\n\n\n

Size\nexclusion chromatography can separate nanoparticles according to their shape\nand size and has the advantages of short separation time, narrow bandwidth,\nhigh sensitivity, and low sample loss.<\/p>\n\n\n\n

Magnetic\nseparation<\/p>\n\n\n\n

Magnetic\nseparation is an effective method to separate nanoparticles by magnetic force.\nMagnetic separation in the form of axial flow has been developed in the early\nyears, which can achieve the effect of efficient separation by changing the\nnumber of channels, the size of channels, the length of separators, and\nmagnetic coils.<\/p>\n\n\n\n

If\nnanoparticles are with similar particle sizes, it will be difficult to separate\nthem by gradient centrifugation and ultrafiltration. Thus, the separation of\nspecific target nanoparticles can be achieved by using selectively capturing\nmagnetic nanoparticles. According to the surface chemical properties of the\ntarget nanoparticles, the magnetic nanoparticles with high selectivity to\ncapture the target nanoparticles are designed and synthesized, and the two are\nmixed, and then the magnetic field is used to achieve the purpose of specific\nseparation.<\/p>\n\n\n\n

Hybrid-type\nseparation<\/p>\n\n\n\n

In\nrecent years, hybrid separation technologies (dielectrophoresis-assisted,\nmagnetophoresis-assisted, acoustophoresis-assisted and optophoresis-assisted)\nhave been developed by combining the advantages of passive and active methods.\nTherefore, these hybrid methods can take advantage of the active method to\nensure high throughput and additional controllability, while the passive mode\nensures the ability to process multiple samples at the same time. However, the\nhybrid separation also has several limitations, such as additional power supply\nand complicated operating settings. In addition, the separation mechanism can\nonly operate under strict conditions, such as a specific pH range or NaCl\nconcentration range. Although the individual operating mechanism is very\nsimple, due to the coupling of experimental parameters such as solution\nsalinity, conductivity and viscosity, flow rate and flow pattern, pressure, etc.,\nthe combination of two or more driving forces makes the experimental operation\ncomplicated stand-up.<\/p>\n\n\n\n

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Figure 1. The working principle of the device for nanoparticle separation. <\/figcaption><\/figure><\/div>\n\n\n\n

To\nsolve this, Professor Taesung Kim (Department of Mechanical Engineering, Ulsan\nNational Institute of Science and Technology, Republic of Korea) and his colleagues\ndescribe a new hybrid technology that combines diffusion permeation (DP) and\nelectrophoresis (EP) to achieve the separation of nanoparticles, called low potential\nassisted diffusion (LEPDP) technology (Figure 1). Detailed results could be\nfound on Lab on\na Chip<\/em><\/a>.<\/p>\n\n\n\n

In the presence of an electrolyte concentration gradient, DP occurs spontaneously, and the diffusion mobility can be controlled by changing the type and\/or strength of the buffer solution, thereby actively controlling the migration speed of the nanoparticles. In addition, EP acts on charged particles in the presence of an electric field, thereby allowing another active control of the electrophoretic mobility of nanoparticles. Therefore, due to the interaction between the concentration gradient and the electric field, LEPDP takes advantage of the advantages of DP and EP. In other words, the concentration of the electrolyte determines the conductivity of the solution, so the combination of DP and EP can play a complementary role. <\/p>\n\n\n\n

They first proved that the LEPDP effect makes it possible to separate nanoparticles (such as PS, SiO2<\/sub><\/a>, PLA<\/a> (CD Bioparticles, Shirley, NY, USA, concentration 0.05% w\/v)) with different Zeta potentials. In other words, the nanoparticles with the highest zeta potential have the best separation effect because they have the fastest migration speed on the main channel, which can realize the separation of nanoparticles based on surface charge. On this basis, they proved that the same separation device can be applied to the particle size separation experiments of different PS nanoparticles with diameters of 500, 200, and 50 nm. That is to say, under the LEPDP effect, nanoparticles of different sizes show different migration speeds and change their migration directions. In addition, they conducted an off-chip analysis by extracting some separated nanoparticle samples from the chip and confirmed that the separation performance was as high as 95% for the 200 and 500 nm nanoparticles separation. Professor Kim said: “We anticipate that our multi-physics-based nanoparticle separation mechanism relying on the nonlinear but synergistic LEPDP effect would not only provide a novel nanoparticle separation technique but also shows remarkable potential for enabling sub-100-nm nanoparticle separation in the near future.” <\/p>\n\n\n\n

Reference
Lee, K., Lee, J., Ha, D., Kim, M., & Kim, T. (2020). Low-electric-potential-assisted diffusiophoresis for continuous separation of nanoparticles on a chip. Lab on a Chip<\/em>, 20(15), 2735-2747. <\/p><\/blockquote>\n","protected":false},"excerpt":{"rendered":"

With the rapid development of nanotechnology, nanoparticles have been mass-produced and widely used in daily life. Continuous separation of nanoparticles<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7,2],"tags":[55,5,56,11],"class_list":["post-212","post","type-post","status-publish","format-standard","hentry","category-applications","category-nanoparticles","tag-nanoparticle-separation","tag-nanoparticles","tag-pla-nanoparticles","tag-silica-nanoparticles"],"_links":{"self":[{"href":"https:\/\/www.cd-bioparticles.com\/blog\/wp-json\/wp\/v2\/posts\/212","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.cd-bioparticles.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.cd-bioparticles.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.cd-bioparticles.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.cd-bioparticles.com\/blog\/wp-json\/wp\/v2\/comments?post=212"}],"version-history":[{"count":1,"href":"https:\/\/www.cd-bioparticles.com\/blog\/wp-json\/wp\/v2\/posts\/212\/revisions"}],"predecessor-version":[{"id":215,"href":"https:\/\/www.cd-bioparticles.com\/blog\/wp-json\/wp\/v2\/posts\/212\/revisions\/215"}],"wp:attachment":[{"href":"https:\/\/www.cd-bioparticles.com\/blog\/wp-json\/wp\/v2\/media?parent=212"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.cd-bioparticles.com\/blog\/wp-json\/wp\/v2\/categories?post=212"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.cd-bioparticles.com\/blog\/wp-json\/wp\/v2\/tags?post=212"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}