Related Experiment Video
Updated: Feb 3, 2026
10:27
The Evolution of Silica Nanoparticle-polyester Coatings on Surfaces Exposed to Sunlight
Published on: October 11, 2016
10.0K
Quantification and Stability Determination of Surface Amine Groups on Silica Nanoparticles Using Solution NMR
Filip Kunc1, Vinod Balhara1, Andreas Brinkmann1
1National Research Council Canada , Metrology Research Centre, Ottawa , Ontario K1A 0R6 , Canada.
Analytical Chemistry
|October 30, 2018
Summary
We developed a dissolution-quantitative 1H NMR (qNMR) method to accurately measure amine functional groups on silica nanoparticles. This method reveals significant batch-to-batch variability in commercial samples and assesses amine stability, crucial for nanomaterial applications.
Area of Science:
- Materials Science
- Nanotechnology
- Analytical Chemistry
Background:
- Surface chemistry dictates nanomaterial performance in composites, devices, and biomedical applications.
- Accurate quantification of surface functional groups is essential for nanotoxicology and material characterization.
Purpose of the Study:
- To develop and optimize a dissolution protocol coupled with quantitative 1H NMR (qNMR) for determining amine content on silica nanoparticles.
- To assess the batch-to-batch variability of aminated silica nanoparticles from commercial suppliers.
- To evaluate the stability of aminated silica nanoparticles under various conditions.
Main Methods:
- Optimized a dissolution protocol involving base concentration, silica mass, time, temperature, and agitation for adequate NMR signal.
- Utilized quantitative 1H NMR (qNMR) to determine amine content after dissolution.
- Compared qNMR results with ninhydrin colorimetric assays.
- Synthesized silica nanoparticles with varying amine chain lengths and loadings.
- Examined nanoparticle stability in water at different temperatures.
Main Results:
- The dissolution-qNMR protocol accurately quantifies amine content, revealing up to 50% batch-to-batch variability in commercial aminated silicas.
- qNMR provided higher amine content measurements compared to the ninhydrin assay.
- Significant loss of amine groups was observed in water, accelerated by higher temperatures and surface coverage.
- Longer-chain amines exhibited greater stability.
Conclusions:
- The developed dissolution-qNMR method is crucial for accurate surface functionalization quantification, especially given commercial sample variability.
- Aminated silica nanoparticles exhibit instability in aqueous environments, with loss dependent on temperature, surface coverage, and amine chain length.
- Understanding and quantifying surface functionalization and its stability is vital for reliable nanomaterial development and application.
More Related Videos
Related Concept Videos
01:19NMR Spectroscopy Of Amines
11.1K
In proton NMR spectroscopy, primary amines and secondary amines showcase their N–H protons as a broad signal in the chemical shift range between δ 0.5 and 5 ppm. The exact position in this range depends on several factors, including sample concentration, hydrogen bonding, and the type of solvent used. Since amine protons undergo fast proton exchange in solution, the protons are labile and therefore do not participate in any splitting with adjacent protons. Thus, the observed peak is...
11.1K
04:08Determining the pH of Salt Solutions
48.1K
The pH of a salt solution is determined by its component anions and cations. Salts that contain pH-neutral anions and the hydronium ion-producing cations form a solution with a pH less than 7. For example, in ammonium nitrate (NH4NO3) solution, NO3− ions do not react with water whereas NH4+ ions produce the hydronium ions resulting in the acidic solution. In contrast, salts that contain pH-neutral cations and the hydroxide ion-producing anions form a solution with a pH greater than 7. For...
48.1K
03:18Nuclear Stability
23.3K
Protons and neutrons, collectively called nucleons, are packed together tightly in a nucleus. With a radius of about 10−15 meters, a nucleus is quite small compared to the radius of the entire atom, which is about 10−10 meters. Nuclei are extremely dense compared to bulk matter, averaging 1.8 × 1014 grams per cubic centimeter. If the earth’s density were equal to the average nuclear density, the earth’s radius would be only about 200 meters.
To hold positively charged protons together...
To hold positively charged protons together...
23.3K
01:53RNA Stability
35.7K
Intact DNA strands can be found in fossils, while scientists sometimes struggle to keep RNA intact under laboratory conditions. The structural variations between RNA and DNA underlie the differences in their stability and longevity. Because DNA is double-stranded, it is inherently more stable. The single-stranded structure of RNA is less stable but also more flexible and can form weak internal bonds. Additionally, most RNAs in the cell are relatively short, while DNA can be up to 250 million...
35.7K
01:19Amines to Amides: Acylation of Amines
3.5K
Various carboxylic acid derivatives (such as acid chlorides, esters, and anhydrides) can be used for the acylation of amines to yield amides. The reaction requires two equivalents of amines. The first amine molecule functions as a nucleophile and attacks the carbonyl carbon to produce a tetrahedral intermediate. This is followed by the loss of the leaving group and restoration of the C=O bond.
Next, the second equivalent of amine serves as a Brønsted base and deprotonates the quaternary...
Next, the second equivalent of amine serves as a Brønsted base and deprotonates the quaternary...
3.5K
01:30Preparation of Amines: Alkylation of Ammonia and Amines
4.7K
Alkylation is one of the methods used to prepare amines. Direct alkylation of ammonia or a primary amine with an alkyl halide gives polyalkylated amines along with a quaternary ammonium salt through successive SN2 reactions. This process of making the quaternary salt through the direct alkylation method is called exhaustive alkylation.
Each alkylation step makes the nitrogen center more nucleophilic, which triggers successive alkylations until a quaternary ammonium salt is formed. Considering...
Each alkylation step makes the nitrogen center more nucleophilic, which triggers successive alkylations until a quaternary ammonium salt is formed. Considering...
4.7K