Silica nanoparticles (SiO2 NPs) are microscopic grains of silicon dioxide, a chemical naturally found everywhere, in sand, quartz and glass. These nanoparticles are incredibly powerful, they're incredibly small and extremely weird on the surface. SiO2 NPs are applied to many sectors from electronics to drug delivery, diagnostics and materials science. Silicon's atomic number 14 is the metalloid which, along with oxygen, makes all sorts of nanomaterials. Biocompatibility, functionalization capability and use in a variety of different fields make these nanoparticles a rapidly emerging scientific field.
Silica nanoparticles are generally between 1 and 100 nanometers in size. These nanoparticles can be amorphous or crystallized (the amorphous version tends to be used most often in practice). They're tiny, their surface-to-volume ratio is high, and they can be used in everything from drug delivery to imaging to sensor construction.
It is the shape of the silica nanoparticles that determines how they behave and work. SiO2 NPs have silicon dioxide embedded in their center, and are usually a porous bed of linked silicon and oxygen atoms. The silicon atoms are normally tetrahedral with four oxygen atoms in Si-O-Si. This underlying structure renders the particles inert and elastic. Since the silica is porous, particle size, surface area and porosity can all be tuned for a given application.
The surface of silica nanoparticles can also be functionalized with chemical motifs to adapt it to biological cells or to substances. Hydrophilic groups such as hydroxyl groups (-OH) can usually be found on the surface of silica nanoparticles, for example. Such surface groups can then be joined to chemical bonds such as amino groups (-NH2), carboxyl groups (-COOH) or chains of polyethylene glycol (PEG) for biocompatibility, stability and targeting.
It can also be modified during synthesis for various features. Mesoporous silica nanoparticles (MSNs, for instance) have an organized hole in which drugs or other molecules can be held. And can be shaped in specific forms, spherical, rod or tubular, as needed.
Silica nanoparticles have many properties, and therefore it is ideal for several technological, industrial and biomedical purposes. The largest are some of the following properties:
1. Dimensions and Surface Area: Because silica nanoparticles are so small (from 1 to 100 nanometers in size), their surface area is extremely large. That large surface area is a boon for loading drugs, surface functionalization and contact with biological mechanisms.
2. Biocompatibility: SiO2 nanoparticles are generally biocompatible, that is, they don't create major toxic reactions when placed in living systems. That makes them perfect candidates for biomedical use, like drug delivery and imaging.
3. Porosity: Silica nanoparticles, particularly mesoporous silica nanoparticles can be very porous to store and release molecules like drugs precisely controlled. You can manipulate the size of pore to fit particular molecules.
4. Surface Modifiability: The surface hydroxyl groups of Silica nanoparticles can easily be modified by adding any number of functional groups. They're therefore very adaptable for targeting specific cells or tissues, enhancing stability, or increasing solubility in biological fluids.
5. Optical Characteristics: Silica nanoparticles are translucent at the visible end of the spectrum and thus can be used in applications such as drug delivery and imaging without hampering optical detection techniques. You can even pair them with fluorescent or contrast material for enhanced imaging.
6. Stability: Silica nanoparticles are chemically stable, don't degrade and can tolerate a variety of environments. They are therefore long-term applications ready for application in areas such as medical and industrial.
7. Low Toxicity: Silicon dioxide as a material is generally inert and the nanoparticles are less cytotoxic than other nanoparticles making it ideal for medical purposes. But the toxicity of silica nanoparticles is variable, depending on size, shape and surface.
The density of silica nanoparticles is also a key indicator of their behavior in many applications. Silica is not particularly dense: its bulk density typically is between 2.0 and 2.5 g/cm3. But the weight of silica nanoparticles depends on size, surface functionalization and porosity. For instance, porous silica nanoparticles (MSNs) might be denser and solid silica nanoparticles more dense.
The amount of matter contained in the nanoparticles matters when it comes to drug delivery and other biomedical use. It alters the particle's capacity to penetrate tissues, its time in the body and its stability. For instance, the higher the density, the faster a suspension will settle, and the lower the density, the better the nanoparticles can spread out and travel in the bloodstream.
In any use case, the number of particles of silica determines the behavior. Silica is an impermeable, bulk density ranges from 2.0–2.5 g/cm3. But the density of silica nanoparticles fluctuates with size, surface functionalization and porosity. Mesoporous silica nanoparticles (MSNs) for example, might be denser as they're porous, while solid silica nanoparticles can be denser.
And it's their density that matters for delivery of drugs or other biomedical functions. It influences the particle's penetration rate, body diffusion time and total titration. The denser, for example, the faster the suspension could settle and the thinner, the more likely it is that the nanoparticles will remain scattered and flow better in the blood.
Synthesis of silica nanoparticles is a matter of different processes and can be tailored to obtain particles of specific size, surface quality and porosity. Some of the most popular synthesis algorithms are:
Stober Method: One of the most popular methods for silica nanoparticles is the Stober method hydrolysis and condensation of TEOS in an alcohol (usually ethanol) and an alkaline catalyst. It creates monodisperse silica nanoparticles with defined size.
Sol-Gel process: Sol-gel process converts a liquid precursor like TEOS into a gel and into a solid nanoparticle. The sol-gel technique is very versatile and we can make silica nanoparticles in various shapes, sizes and surface morphologies.
Microemulsion Process: Microemulsion is used to manufacture the nanoparticles of silica in the microemulsion that is a mixture of water, oil and surfactants. This process can be used to produce nanoparticles with specified sizes and shapes, and it is usually employed for making extremely stable silica nanoparticles.
Hydrothermal Synthesis: Silica precursors are reacting in high temperature, high pressure aqueous solution. It is especially useful for the production of mesoporous silica nanoparticles and provides micro-control over particle size and surface characteristics.
Template-Assisted Synthesis: In this process, a template (either a polymer or a metal oxide) is placed on top of the silica nanoparticles to instruct them in the process. The template is scraped off at synthesis to get the nanoparticle shape that one desires.
Fig.1 Basic scheme of synthesis of silica nanoparticles. (Karande, Sudip D., et al., 2021)
Silica nanoparticles can be applied in a wide variety of applications because of their distinctive features of biocompatibility, functionalization and stability. The most common use cases are:
Carrier for Drug Delivery: Silica nanoparticles have become a preferred carrier for drug delivery because of the high surface area, biocompatibility, and capability to encapsulate various drugs. They can be adapted to specific cells or tissues, and their porousness makes them more capable of delivering drugs selectively, less side-effect-based and more effective.
Imaging and Diagnostics: Silica nanoparticles are used in diagnostic imaging (fluorescence and magnetic resonance imaging, MRI) because they can be easily altered by developing agents. They can improve the contrast of imaging methods, leading to earlier detection of diseases such as cancer.
Sensors: Silicon nanoparticles are widely used in chemical and biological sensors due to their large surface area and reactivity. They detect molecules or viruses by interacting with them and sending out measurable signals.
Chemical reactions: Silica nanoparticles are catalysts or catalyst boosters. Their large surface area is a perfect starting point for catalytic reactions, and they remain stable over time.
Cosmetics & Personal Care: Silica nanoparticles are utilized in cosmetics like sunscreens, anti-aging creams, etc. They are silky and carry active compounds making them perfect for skincare.
Silica nanoparticles have demonstrated significant potential as drug delivery systems. The large surface area of silica NPs allows for the loading of a high payload of drugs, while their surface can be easily modified to target specific cells or tissues. Additionally, mesoporous silica nanoparticles (MSNs) offer a unique advantage due to their well-defined pore structures, which can be engineered to control the release of drugs over time.
The functionalization of silica nanoparticles with targeting molecules, such as antibodies or peptides, enables selective delivery to diseased tissues, such as cancer cells. This targeted approach minimizes damage to healthy cells, reducing side effects typically associated with conventional chemotherapy. Furthermore, silica nanoparticles can protect drugs from premature degradation in the body, improving their stability and bioavailability.
In addition to small molecule drugs, silica nanoparticles have also been explored for the delivery of large biomolecules, such as proteins, nucleic acids, and RNA. By modifying the surface of silica nanoparticles with ligands that facilitate cellular uptake, these nanoparticles can be used for gene therapy or vaccine delivery.
BOC Sciences offers a wide range of silica nanoparticle products, as well as customized solutions in different types and sizes, to support a variety of research and application needs. Below is the list of silica nanoparticles we can provide, if you have additional requirements, please contact us to customize the synthesis of your silica nanoparticles.
| Product Type | Available Sizes | Price |
| Basic Silica Particles | 10 nm, 20 nm, 40 nm, 50 nm, 60 nm, 100 nm, 280 nm | Inquiry |
| Conjugated Silica Particles | 10 nm, 20 nm, 40 nm, 50 nm, 60 nm, 100 nm, 280 nm | Inquiry |
| Coated Silica Particles | 10 nm, 20 nm, 40 nm, 50 nm, 60 nm, 100 nm, 280 nm | Inquiry |
| Fluorescent Silica Particles | 10 nm, 20 nm, 40 nm, 50 nm, 60 nm, 100 nm, 280 nm | Inquiry |
| Coloured Silica Particles | 10 nm, 20 nm, 40 nm, 50 nm, 60 nm, 100 nm, 280 nm | Inquiry |
| Functional Silica Particles | 10 nm, 20 nm, 40 nm, 50 nm, 60 nm, 100 nm, 280 nm | Inquiry |
| Product Type | Price |
| Mesoporous Silica Nanoparticles | Inquiry |
| Gold Coated Silica Nanoparticles | Inquiry |
| Amine Functionalized Silica Nanoparticles | Inquiry |
| Amorphous Silica Nanoparticles | Inquiry |
| Colloidal Silica Nanoparticles | Inquiry |
| Core Shell Silica Nanoparticles | Inquiry |
| Hollow Mesoporous Silica Nanoparticles | Inquiry |
| Hydrophobic Silica Nanoparticles | Inquiry |
| Magnetic Silica Nanoparticles | Inquiry |
Silica nanoparticles are synthesized using the sol-gel method, hydrolyzing precursors like tetraethyl orthosilicate (TEOS) in water-alcohol mixtures with catalysts.
Mesoporous silica nanoparticles are silica-based structures with uniform, nanoscale pores, offering high surface area and tunable porosity for drug delivery and catalysis.
Mesoporous silica nanoparticles are synthesized by templating surfactants like CTAB in TEOS, followed by surfactant removal via calcination or solvent extraction.
Silica nanoparticles degrade through hydrolysis or dissolution in aqueous environments, producing non-toxic silicic acid, influenced by pH, surface properties, and structure.
Silica nanoparticles are characterized by techniques like TEM, SEM, DLS for size, BET for porosity, and FTIR or XRD for chemical and structural properties.
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