Editorial Feature

Silicon Dioxide Nanoparticles (Nanosilica): Properties & Applications

Silicon dioxide nanoparticles, also known as silica nanoparticles or nanosilica, are the basis for a great deal of biomedical research due to their stability, low toxicity and ability to be functionalized with a range of molecules and polymers.

Silicon dioxide powder or Silica. Food additive E551, anti-caking agent. Silicon oxide. White chemical dust scattered on dark surface.

Image Credit: AB-7272/Shutterstock.com

Nanosilica particles are divided into P-type and S-type according to their structure. The P-type particles are characterized by numerous nanopores, which have a pore rate of 0.61 ml/g and exhibit a higher ultraviolet reflectivity compared to the S-type; the latter also has a comparatively smaller surface area.

Nanosilica are the second most produced nanomaterial globally. Due to this, several research papers in recent decades have focused on the potential applications of nanosilica in multiple industries and their potential toxicity.

Chemical Properties of Nanosilica

Chemical Data

Chemical symbol SiO2
CAS No 7631-86-9
Group Silicon 14
Oxygen 16
Electronic configuration Silicon [Ne] 3s2 3p2
Oxygen [He] 2s2 2p4

Chemical Composition


Content (%)

Silicon 46.83
Oxygen 53.33

Physical Properties of Nanosilica

Nanosilica appears in the form of a white powder. The table below provides the physical properties of these nanoparticles.




Density 2.4 g/cm3 0.086 lb/in3
Molar Mass 59.96 g/mol -

Thermal Properties of Nanosilica

Properties Metric Imperial
Melting Point 1600°C 2912°F
Boling Point 2230°C 4046°F

Applications of Nanosilica

The chief applications of nanosilica are as an additive for the manufacture of rubber and plastics; as a strengthening filler for concrete and other construction composites; and as a stable, non-toxic platform for biomedical applications such as drug delivery and theranostics.

Nanosilica for Biomedical Applications

Nanosilica are an emerging technology in the biomedical field due to their favorable biocompatibility, large surface area, and controllable particle size. These beneficial properties also make SiO2 nanoparticles useful materials in the food industry.

Several economical and convenient strategies have been developed to manufacture nanosilica based on common synthesis methods. While many successful studies have demonstrated the efficaciousness of SiO2 nanoparticles for treating various cancers and diagnosing diseases, challenges persist.

One of the main challenges associated with using nanosilica in biomedical applications is to do with their toxicity and toxicity mechanisms. This is still a poorly understood area of research, with in vitro and in vivo studies in their infancy.

Nonporous Nanosilica: Biomedical Applications and Synthesis

Nonporous nanosilica, also termed N-SiNPs, are particularly useful for biomedical applications such as drug delivery and disease diagnosis due to their excellent biocompatibility. These nanoparticles are irregular and amorphous, having no standard structural shape.

N-SiNPs are widely used in biomedical applications such as medical imaging, as stabilizing agents for therapeutics, and enzyme encapsulation. There are two main routes for synthesizing these nanoparticles: thermal methods and wet methods. Wet preparation approaches include precipitation and chemical sol-gel methods.

Mesoporous Nanosilica: Biomedical Applications and Synthesis

M-SiNPs (mesoporous silica nanoparticles) have a more regular shape than their nonporous counterparts. These types of nanosilica have beneficial physiochemical properties such as controllable porosity, good biocompatibility, large surface area, and high thermal stability.

Due to these beneficial properties, M-SiNPs are widely employed by biomedical scientists for applications such as catalysis, bioimaging, and drug delivery. Aside from this, M-SiNPs have been employed as platforms for preparing other nanomaterials.

M-SiNPs are commonly prepared using a number of methods. These include improved Stöber synthesis methods, evaporation-induced self-assembly, and the use of liquid crystal templates (template synthesis) and one-pot synthesis.

Various capsules, tablets and medicine in shop trolley on a beige background.

Image Credit: CHUYKO SERGEY/Shutterstock.com

Nanosilica as Drug Delivery Systems

As mentioned above, one of the main biomedical applications for nanosilica is as carriers for drug delivery, delivered via eye drops, intravenous injections, oral tablets, or pulmonary inhalation routes.

Research has been conducted into the use of nanosilica to deliver drugs to target various cancers such as liver cancer, lung cancer, glioblastoma, and colon cancer. They have been employed to treat viral infections, myocardial infarction, colitis, and neurodegenerative diseases as well as various cancers.

Medical Imaging

Functionalized nanosilica has been used in MRI, light imaging, dual-mode imaging, radio-labeled imaging, and ultrasound imaging.


Patients can be easily exposed to nanoparticles through eating, breathing, and touching them. Their small size, high surface-to-volume ratios, and enhanced surface reactivity make them a concern for scientists, making studies on their toxicity a crucial endeavor in the biomedical and food industries.

For this reason, and the fact that they are widely employed in medical imaging and drug delivery, the in vitro and in vivo toxicity of nanosilica has been extensively studied.

Research into potential toxicity in respiratory systems has indicated potential oxidative stress in human lung fibroblast cells related to the cytotoxicity of nanosilica. Other studies have indicated a relationship between nanosilica and elevated transcription of chemokines, which are pro-inflammatory.

Furthermore, due to their small size, silicon dioxide nanoparticles can cross the blood brain barrier, with concerns being raised in research about their potential link to neurodegenerative disorders such as Alzheimer's disease. Nanosilica can also potentially cause mitochondrial dysfunction, leading to corneal damage in the eye.

Research has also indicated potential nanosilica-linked toxicity in the gastrointestinal, digestive, and circulatory systems. Clearly, more research is needed into the potential toxicity of silicon dioxide nanoparticles, especially as they are becoming more commonly employed in the biomedical field.

See More: How Are Nanoscale Approaches Changing the Vaccine Game?

References and Further Reading

Huang, Y et al. (2022) Silica nanoparticles: Biomedical applications and toxicity Biomedicine & Pharmacotherapy 151, 113053 [online] sciencedirect.com. Available at: https://doi.org/10.1016/j.biopha.2022.113053

Disclaimer: The views expressed here are those of the author expressed in their private capacity and do not necessarily represent the views of AZoM.com Limited T/A AZoNetwork the owner and operator of this website. This disclaimer forms part of the Terms and conditions of use of this website.

Reginald Davey

Written by

Reginald Davey

Reg Davey is a freelance copywriter and editor based in Nottingham in the United Kingdom. Writing for AZoNetwork represents the coming together of various interests and fields he has been interested and involved in over the years, including Microbiology, Biomedical Sciences, and Environmental Science.


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  1. Daniel E. Martinez Daniel E. Martinez Mexico says:

    This type of nanoparticles, still has the piezoelctric property

  2. hassan javid hassan javid Islamic Republic of Pakistan says:

    is nano silica harmful as nanofluid in machining setup?

The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of AZoNano.com.

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