Separation Membranes
Membrane separation is the process of separating components in a mixture for example solids and liquids, similar to filtering, but membrane separation can separate much smaller materials. Membranes allow the transport of one component more readily than another due to physical and chemical differences between the components. The separation of biomolecules and other nanoparticles is a vital step in several analytical and diagnostic techniques. Various techniques have been developed for the separation of nanomaterials using membranes. Some methods found in literature are given below.
Porous nanocrystalline silicon membrane
Porous nanocrystalline silicon (pnc-Si) is a 15 nm thin free-standing membrane material with applications in small-scale separations, biosensors, cell culture, and lab-on-a-chip devices. Pnc-Si has already been shown to exhibit high permeability to diffusing species and selectivity based on molecular size or charge. This pnc-Si membranes can be used in dead-end filtration to fractionate gold nanoparticles and protein size ladders with better than 5 nm resolution with insignificant sample loss and little dilution of the filtrate. These performance characteristics, combined with scalable manufacturing, make pnc-Si filtration a straightforward solution to many nanoparticle and biological separation problems.
Recyclable supramolecular membrane
Krieg and his fellow researchers have nanostructured supramolecular membranes prepared from fibrous assemblies in water. The membranes are robust due to strong hydrophobic interactions, allowing their application in the size-selective separation of both metal and semiconductor nanoparticles. A thin (12 µm) membrane is used for filtration (5 nm cutoff), and a thicker (45 µm) membrane allows for size-selective chromatography in the sub-5 nm domain. Unlike conventional membranes, supramolecular membranes can be disassembled using organic solvent, cleaned, reassembled and reused multiple times.
Solid state nanopores
Anmiv S Prabhu and his colleagues have developed a solid state nanopore-based set-up as an efficient separation platform for the separation of biomolecules and other nanoparticles. A single 150 nm pore was fabricated in a 50 nm thick free-standing silicon nitride membrane by focused-ion-beam milling and was chemically modified with (3-aminopropyl)triethoxysilane to change its surface charge density. This chemically modified membrane was then used to separate 22 and 58 nm polystyrene nanoparticles in solution. Once optimized, this approach can readily be scaled up to nanopore arrays which would function as a key component of next-generation nanosieving systems.
Commercial Nanoparticle Separator: UltraSM® SepCon™
Nanoparticle Separation
This device is specifically engineered for nanomaterials Separation or clean up.Features of this device for nanomaterials include:
• Pure Silicon composition
• High permeability: allows for rapid transport and high flow rates
• Precisely controlled nanopores: efficiently separates your nanoparticles based on size
• Less than 30 nm thick: does not trap nanoparticles or other molecules in pores, unlike polymeric membranes
• Negatively charged membrane: significantly reduces binding and loss compared to conventional materials
• Compatible with standard bench top centrifuges: easy to use with existing equipment.
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