UniSil® is a series of monodisperse spherical porous silica gels used for chromatography, produced by Suzhou Nanomicrotech Co. Ltd. from its unique patented technology that is developed in-house. UniSil® series of products meets the requirements of high performance liquid chromatography (HPLC) analysis in the laboratory and preparative separations in industry scale. The monodisperse spherical porous silica gel has distinct advantages, such as highly uniform particle size, perfect sphericity, outstanding mechanical strength, easy column packing, high column efficiency, good resolution, and low back pressure, UniSil® has already been widely used in analysis and separation of organic compounds, natural products, and large biomolecules. Nano-Micro is proud to be the leader of monodisperse chromatography silica gel with capability to produce in commercial scale.

Figure 1. SEM micrographs of UniSil® monodisperse chromatography silica gel

High uniformity of particle size and perfect spherical shape
UniSil® silica gel media are made to in precise particle sizes with exceedingly high uniformity and perfect spherical shape (Figures 2 and 3). When compared to other commercial chromatography silica gels ( with broader particle size distribution), UniSil® has great advantages of easy column packing, low back pressure, high column efficiency, good resolution, stable column bed and reduced frit plugging.

Figure 2. Comparison of UniSil® and well-known international brand chromatography silica gel

Figure 3. Particle size distribution of UniSil® and well-known international brand chromatography silica gel

Figure 4. Flow characteristics in chromatography media of different particle size distributions
Optimal pore structure
The pore structure of silica gel has a great influence on its mechanical strength, separation ability, and loading capacity. Nano-Micro not only controls precisely the particle size and size distribution of the silica gel, but also optimizes pore structure forming, desired surface area and pore volume. As the result, UniSil® silica gel has high loading capacity, strong mechanical strength, and superior separation capability.
Unique surface bonding technology
The selectivity and lifetime of a silica gel are often determined by the bonding phase on its surface and end-capping. In addition to the world leading technology of making silica gel, Nano-Micro has developed unique techniques of surface bonding and end-capping, which enable UniSil® to be used with a broad pH range of application, good separation selectivity, and peak symmetry. To meet customer needs, Nano-Micro also provides a variety of polar and non-polar bonded phase silica gel (C18,C8,C4,Phenyl,NH2,CN,Diol).
Figure 5 showed the separation of various chemical substances by UniSil® 5-120 C18 reverse phase silica gel media, including pyridine (alkaline compound). The high column efficiency and sharp and symmetric peaks indicated the minimal residual silanol groups on the surface (due to good end-capping).

Figure 5. Chromatographic separation of various compounds by UniSil® 5-120 C18
Exceptional chemical stability and resistance against acid and base
Nano-Micro’s unique bonding and end-capping techniques gave UniSil® exceptional resistance to acidic and alkaline environment. Figure 6 showed a comparison of UniSil® 10-100 C8 with a leading commercial brand, in terms of column efficiency (after alternating elution of columns with acidic and alkaline solutions). The results indicated that the column packed with UniSil® maintains the column efficiency much better than the other with commercial silica gels, suggesting a stronger resistance against acid and base.

Figure 6. Comparison of column efficiency, between UniSil® 10-100 C8 (green) and leading commercial brand (red), after treatment with acid and base
Large scale production capability and lot-to-lot consistency
State-of-the-art manufacturing facility at Nano-Micro allows a large scale production of UniSil® to meet the demands of industrial separation. Good quality control system also assures the high quality and good lot-to-lot consistency (as shown in Figure 7).

Figure 7. Lot-to-lot consistency of UniSil® silica gel
Applications
Nano-Micro has an in-house application development group with vast experiences. This group provides customers with a lot of technical services, from process development to technical transfer for production (industrial scale). UniSil® silica gel media have been successfully applied to the isolation and purification, including plant extracts (huperzine A, ginkgolide, panax notoginseng saponins), antibiotics(vancomycin, daptomycin, caspofungin, tiacumicin, Pneumocandin B0, cyclosprin, erythromycin), polypeptides (tacrolimus, thymalfasin, bivalirudin) and others(cod liver oil, bortezomib, flurbiprofen axetil), etc.
List of Products
Nano-Micro supplies spherical silica gel media in the size range of 1.7 to 50 μm, with different pore sizes, meeting the needs of high performance chromatographic (HPLC) analysis in the lab and also preparative separation in industrial scale.

* Custom-made UniSil® products are available upon request:
a. Particle size:Any size between 1 and 50 μm;
b. Pore size:Any size between 60 and 1000 Å;
c. Bond phase:Special functional groups other than listed above.
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