Silica nanoparticles support a wide range of applications because their size, porosity, surface chemistry, and architecture can be tailored for different functions. Their mechanical and absorptive properties are useful in industrial materials, while their tunable surfaces and ability to form porous particles or coatings make silica valuable in biomedical, analytical, catalytic, and optical research.
Silica also plays an important role in complex nanomaterial architectures. It can serve as a porous carrier, functional surface, protective shell, or spacer between materials with different optical, magnetic, or chemical properties. The examples below highlight several ways silica nanoparticles and silica-coated nanomaterials are used across these fields.
Explore silica nanoparticles for your application
Compare solid and mesoporous silica nanoparticles with different particle sizes, porosities, and surface chemistries.
Industrial & Materials Applications
Silica is used across a broad range of industrial applications because of its mechanical, absorptive, and surface properties. Examples include:
- Polishing: Abrasive silica particles can be used to polish materials such as silicon wafers.
- Friction control: Silica can reduce friction and has been incorporated into coatings used on surfaces ranging from waxed floors to railroad tracks.
- Papermaking: Its absorptive properties allow silica to function as a drainage aid.
- Rubber, plastics & concrete: Silica can serve as a binding or reinforcing component in composite materials.
At the nanoscale, additional control over particle size, porosity, surface chemistry, and particle architecture expands silica into biomedical, optical, catalytic, separation, and analytical applications.
Nanomedicine & Drug Delivery
Cell Tracking & Biomedical Imaging
Inorganic nanoparticles have been investigated for in vivo cell tracking because nanoscale particles can be taken up by cells and their material properties can provide contrast relative to surrounding biological tissue.
One published protocol describes the use of nanoComposix silica nanospheres as an ultrasound contrast material for stem-cell tracking. The work outlines methods for labeling cells with nanoparticles and using the resulting acoustic contrast to improve visualization of the labeled cells.1
For broader information about the use of engineered nanoparticles in biological systems, see Nanobiotechnology.
Mesoporous & Hollow Silica for Drug Delivery
Mesoporous silica nanoparticles (MSNs) and hollow silica nanoparticles (HSNs) have received significant research interest as drug-delivery platforms because of their large internal surface areas, tunable pore structures, and adaptable surface chemistry.
The pores and particle surfaces can be engineered around payload and surface-functionalization requirements, including strategies intended to control interactions with specific tissues or cells. These properties make porous silica a versatile platform for studying loading, delivery, and targeting approaches.
For custom formulation and development programs, see Nanomedicine CDMO Services.
Catalysis
The pores and surface chemistries of mesoporous and hollow silica nanoparticles provide defined environments for catalytic reactions. Catalysts can be incorporated within the internal pores, while pore dimensions can be adjusted to control which molecules can access the catalytic surface.
This combination of high surface area, tunable pore structure, and surface functionalization can provide increased reaction efficiency or selectivity for appropriately designed catalytic systems.
Optical & Plasmonic Applications
Plasmonic Color Thin Films
Silica coatings can help integrate plasmonic nanoparticles into matrices that may be difficult to use with an uncoated metal surface. Silica-coated silver and gold nanoparticles have been incorporated into robust glazes, paints, and other coatings applied to a variety of surfaces.
For additional examples of nanoparticle integration into optical materials, see Nanomaterials for Optical Engineering.
Color-Changing Silica-Coated Silver Nanoplates
Silica-coated silver nanoplates can change color when exposed to liquid or high humidity. Water and dissolved salts can move through the silica shell and interact with the high-curvature edges of the silver nanoplate, where selective dissolution can occur.
As the plate geometry changes, its plasmon resonance shifts and produces a corresponding change in color. The rate of this response can be adjusted through the thickness or porosity of the silica shell.
This architecture has been investigated as an environment-responsive color indicator, including research into indicators that could signal when a wound dressing should be exchanged. Learn more about the optical behavior and stability of Silver Nanoplates.
Surface-Enhanced Spectroscopy
Silica shells can be used to position dyes or other specialized molecules near the surfaces of plasmonic metal nanoparticles. These architectures can be designed to enhance spectroscopic signals associated with the underlying metal nanoparticle, including fluorescence and Raman signals.
The silica layer can therefore become part of a controlled optical architecture in which the composition and spacing between the reporter molecule and plasmonic surface influence the resulting response.
Learn more in Surface-Enhanced Spectroscopy: SERS & SEF.
DNA Extraction & Magnetic Separation
DNA Extraction
Functionalized silica surfaces can bind DNA and provide a platform for nucleic-acid separation. By changing environmental conditions such as pH and salt concentration, interactions between DNA and the silica surface can be controlled to support separation of DNA fragments of different sizes.
This approach can be particularly useful for microscale and microchip-based systems where conventional DNA-extraction methods can be difficult to implement.
Magnetic Separation
Silica-shelled superparamagnetic nanoparticles combine the magnetic properties of the core with the surface and stability characteristics of silica. Silica surfaces can be further functionalized to facilitate interactions with proteins, DNA, or other molecules used in biomedical and separation applications.
Because silica is widely used in stationary phases for biomolecular separation, magnetic silica particles provide a way to translate similar surface interactions into particle-based separation systems. These architectures can be used for separations in solution as well as in microfluidic devices.
A silica coating can also function as an interface or spacer between a magnetic core and another functional material. For example, silica can separate an iron oxide core from a plasmonic metal or fluorescent quantum dot, allowing magnetic and optical properties to be combined within the same particle architecture.
Instrumental Method Development & Reference Materials
Silica nanoparticles are also used as test and reference materials for instrumental method development, including single-particle inductively coupled plasma mass spectrometry (SP-ICP-MS).
Silica presents a particular analytical challenge for ICP-MS because of the relatively high background at the m/z value of silicon's most abundant isotope, 28Si. This makes silica a useful material for developing and evaluating analytical approaches intended to distinguish individual nanoparticle events from background signal.
Application Note: Analysis of SiO2 Nanoparticles by SP-ICP-MS
See how PerkinElmer used nanoComposix silica nanoparticles to address the analytical challenges associated with silicon background and quantify SiO2 nanoparticles using single-particle ICP-MS.
For more information about well-characterized particles for analytical method development, see Reference Material Nanoparticles.
How can silica nanoparticles enable your application?
Talk with our technical team about silica particle size, porosity, surface chemistry, coatings, composite structures, characterization, or custom development.
Selected Literature
- Chen, F.; Jokerst, J. V. Stem Cell Tracking with Nanoparticle-Based Ultrasound Contrast Agents. In Cell Tracking, Methods in Molecular Biology, Vol. 2126; Humana: New York, 2020, pp 141–153.
- Mukherjee, A.; Darlington, T.; Baldwin, R.; Holz, C.; Olson, S.; Kulkarni, P.; DeWeese, T. L.; Getzenberg, R. H.; Ivkov, R.; Lupold, S. E. Development and Screening of a Series of Antibody-Conjugated and Silica-Coated Iron Oxide Nanoparticles for Targeting the Prostate-Specific Membrane Antigen. ChemMedChem 2014, 9, 1356–1360.
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