Use of nanoparticles in water purification

How to cite this article: Theranostics ; 2 1: Multifunctional nanoparticles harboring various functions including targeting, imaging, therapy, and etc have been intensively studied aiming to overcome limitations associated with conventional cancer diagnosis and therapy. Of various nanoparticles, magnetic iron oxide nanoparticles with superparamagnetic property have shown potential as multifunctional nanoparticles for clinical translation because they have been used asmagnetic resonance imaging MRI constrast agents in clinic and their features could be easily tailored by including targeting moieties, fluorescence dyes, or therapeutic agents.

Use of nanoparticles in water purification

Innovations in nanotechnology for water treatment

After the mixed solution was stirred for 12 h, the modified silica nanoparticle, SiO2-APTMS, was isolated and washed by centrifugation 3 times and redispersion in ethanol. To easily check the number of effective amine groups on the surface of silica naoparticle, these modified silica nanoparticles were reacted with a large excess amount more than times excess compared to the amounts of used APTMS of Rhodamine B isothiocyanate RITC to attach fluorescent rhodamine units by forming thiourea linkage, which has become one of the useful bioconjugation methods [ 24 ].

A very similar trend was observed from the modification experiments with DETAS, even though the absorption intensities were much higher due to the multiple amine sites Figure 2 b and Figure S3. These results showing saturation in absorption intensity seem to imply the formation of monolayer of APTMS and DETAS instead of the generation of a thick coating layer in our modification condition.

Illustration of the surface modification of silica nanoparticle by APTMS followed by treatment with a RITC to measure the absorption and b methyl acrylate and ethylenediamine to increase the number of amine sites.

To confirm the formation of monolayer modification, silica nanoparticles before and after the surface modifications were precisely characterized by transmission electron microscopy TEM and dynamic light scattering DLS spectrophotometer.

However, the size measured by DLS clearly showed the increment of the hydrodynamic sizes of SiO2 nanoparticles in water from toand finally to nm Figures 3 d — 3 f ; the size from DLS is usually reported to be bigger than that from TEM due to the surrounded water molecules and swelling effect of surface molecules.

Since the surface-to-volume ratio of nanoparticles is dramatically increased compared to bulk materials, the actual number of aminofunctional groups in the modified silica samples would be reasonably high enough to be directly measured by simple acid-base titration.

Due to the feature of amino group as a weak base and the possible aggregation and scattering problems during the titration, back titration method was employed for the direct measurement of amino groups on the surface of silica nanoparticles.

Back titration is a technique designed to resolve problems when analytes are in nonsoluble solid phase having either too weak or too slow characteristics to give a valid reaction; the unknown concentration of a base sample is determined by reacting it with an excess volume of acid with a known concentration and then titrating the resulting mixture with the standardized base solution to give the differences of the acid concentration which corresponds to the concentration of unknown base sample [ 25 ].

Nanoparticles were separated by centrifugation at 15, rpm for 10 min, and 10 mL of supernatant was collected to be titrated with the standardized 0. Table 1 summarizes the number of amine sites measured by the titration as well as the calculated values from the absorption measurement after treating with RITC.

As expected, the number of amine sites measured by back titration was 7.

Use of nanoparticles in water purification

To check the reproducibility and reliability of our quantitative analysis methods, a further chemical reaction was carried out from the amine sites of SiO2-APTMS, and the number of new functional sites was measured.

For the quantitative conversion of each generation in the amine-terminal dendrimer synthesis, it is known that a terminal primary amine could be successively reacted with methyl acrylate MA and ethylenediamine EDA to form one tertiary amine and two terminal primary amines Figure S5 [ 29 ].

The number of amine sites per nm2 was increased from 2. Measured numbers of silanol and amine sites on the various silica surfaces from references as well as this work.

It is well known that the actual number of aminofunctional groups on the modified surfaces is changed with time due to the instability of surface layers.

It has been also proposed that some amino group on the surface is bent toward the surface, and the bent amino group is interacted with circumjacent silanol group by hydrogen bonding or acid-base interaction to form ion pairs. Such interactions can reduce the actual reactivity of amine groups [ 30 ].

In our surface modification method forming monolayer with amino-functionalized trialkoxysilanes, however, these types of interaction of amine groups with surface silanol groups so-called backbiting interactions were reduced significantly and the reactivity of amino group could be maintained for a long period of time without showing any differences in the reactivity.

Portable water purification - Wikipedia

Precise characterizations with transmission electron microscopy TEM and dynamic light scattering DLS spectrophotometer have confirmed the formation of monolayer modification.

The total number of amino groups on the surface of SiO2 nanoparticle were quantitatively analyzed by a simple acid-base back titration method and the effective number of amino groups for the successive chemical reactions was also determined by spectroscopic measurements after treating with fluorescent Rhodamine B isothiocyanate RITC molecule, showing well-matched results with known values from literatures.

Use of nanoparticles in water purification

Furthermore, the reproducibility and reliability of our quantitative analysis methods were confirmed by checking the change of amine sites of SiO2-APTMS after the quantitative conversion of the terminal primary amine to one tertiary amine and two terminal primary amines by successive reactions with methyl acrylate MA and ethylenediamine EDAa process well-developed in dendrimer synthetic methods.

We believe that our method to generate monolayer modification and analyze the number of amine sites on nanoparticle surface will be useful in nano-bio research applications, such as sensors, diagnosis, and drug or gene deliveries, where reliable and reproducible modification and quantitative analysis are very critical.

Moon are grateful for the award of a BK21 fellowship. View at Google Scholar P. View at Google Scholar K.

Van Der Voort, and E.Jan 06,  · The use of magnetic nanoparticles (magnetite Fe 3 O 4) for separation of water pollutants has already been established in ground water remediation, in particular for the removal of arsenic The conventionally applied “pump-and-treat” technology for groundwater treatment comprises pumping up the groundwater to the surface and further.

Abstract. Nanomaterials offer new opportunities for cancer diagnosis and treatment. Multifunctional nanoparticles harboring various functions including targeting, imaging, therapy, and etc have been intensively studied aiming to overcome limitations associated with conventional cancer diagnosis and therapy.

Portable water purification devices are self-contained, easily transported units used to purify water from untreated sources (such as rivers, lakes, and wells) for drinking purposes. Their main function is to eliminate pathogens, and often also of suspended solids and some unpalatable or toxic compounds..

These units provide an autonomous supply of drinking water . Despite these potential advantages of using nanoparticles to disinfect water, it is important to determine if nanoparticles leach through the treatment technology into finished drinking water and to consider the potential health implications of ingestion of nanoparticles in drinking water.

Scientists are cleaning our drinking water with nanoparticles. August 26, - This drastically increases the value of the active charcoal in water purification,” says Hwang.

Nanoparticles could react with oxygen. There are some hurdles left for Hwang to solve, though. Aug 01,  · Typically, the main use for materials containing silver nanoparticles are antimicrobial applications, such as water filtration, wound care, food packaging, textiles, and so on.

To assess the antibacterial effectiveness of AgNP papers in such applications, some of the potentially interfering.

Scientists are cleaning our drinking water with nanoparticles | ScienceNordic