Nanoparticle Preparation - Science topic

The color of nickel oxide (NiO) nanoparticles prepared by green synthesis can vary depending on the specific method and conditions used for synthesis. Generally, NiO nanoparticles appear as green to black in color. However, the exact color can be influenced by factors such as the size, shape, and surface properties of the nanoparticles, as well as the stabilizing agents or capping agents used in the synthesis process.

how to measure z?

Thank you very much for your insight Hortensia Ortega-Ortíz

I added 100% ethanol and crushed the lyophylised product. I got them in powdered form. However I am yet to check the size by DLS.

If there is any method to obtain them in uniform size below 450nm, please suggest.

Yes having a closed lid would help you not only decrease the contamination but also decrease the amount of carbon dioxide that might be incorporated within your particles.

Some compounds however like hydroxyapatite can be prepared in an open mode as they sometimes need to be prepared in their carbonated form. So your choice would depend on whether you would need the presence of carbon dioxide in your compound or not.

Thanks Dr. Chanda

Your answer is truly appreciated, but I had the impression that they are both amine and they should be reducing agents!

Why would think that they are different?

Sadiqul Hasan

Silk fibroin, like most polymers, is amorphous. Therefore, the diffraction pattern has wide peaks (halos). To determine the size according to the Scherer formula, crystalline samples are used. Perhaps you neglected it. That's why you got that size. If the peak is narrow, then you have determined the approximate size of the crystalline part of silk fibroin.

@ Ibrahim, Collagen nanoparticles can be prepared through three main techniques: chemical, physical, and self-assembly methods. Chemical methods consist of coacervation or complexation and emulsification. Nano collagen can also be fabricated through milling. Milling is a process whereby mechanical energy is applied onto a polymeric material to be broken down into fine nanoparticles. Milling is an inexpensive way to reduce particle size on large production scales. The attached file may show you how you may prepare collagen nanoparticles by self assembly methods.

In the case of testing the antimicrobial activity of silver nanoparticles prepared from a plant extract, it is recommended to perform a minimum inhibitory concentration (MIC) assay to determine the minimum concentration of the silver nanoparticles required to inhibit the growth of the microorganisms being tested. The MIC assay is a standard method for evaluating the antimicrobial activity of a substance, and is commonly used in research studies.

The MIC assay involves testing different concentrations of the silver nanoparticles against the microorganisms in question, and observing the lowest concentration at which there is no visible growth of the microorganisms after a specified incubation period. This concentration is then considered the MIC for that particular microorganism.

While it may be tempting to skip the MIC assay and perform an antimicrobial activity assay directly, it is important to note that such an approach may not provide accurate and reliable results. Without determining the MIC, it is difficult to know whether a negative result in the antimicrobial activity assay is due to the nanoparticles being ineffective or simply not being used at a high enough concentration.

So, it is recommended to perform a MIC assay to determine the minimum inhibitory concentration required to inhibit the growth of the microorganisms being tested. This will provide a reliable and accurate measure of the antimicrobial activity of the nanoparticles.

Jeffry G Weers - this happens, e.g., change of cationic micelles from spherical to rod-like. For ionic surfactants increasing surfactant concentration means also increasing electrolyte concentration changing packing of ionic surfactant head groups.

Dear MJA

We can measure the concentration of Ag nanoparticles prepared by PLAL in water using a variety of techniques, including UV-Vis spectroscopy, dynamic light scattering (DLS), and inductively coupled plasma mass spectrometry (ICP-MS). UV-Vis spectroscopy is a simple and cost-effective method for measuring the concentration of Ag nanoparticles in water. The absorbance of the Ag nanoparticles at a specific wavelength is measured and compared to a standard curve to determine the concentration. DLS is a more accurate method for measuring the size and concentration of Ag nanoparticles in water. The scattered light intensity of the Ag nanoparticles is measured and used to calculate the size and concentration of the particles. ICP-MS is the most accurate method for measuring the concentration of Ag nanoparticles in water. The Ag nanoparticles are dissolved in an acid solution and the concentration of Ag is measured using ICP-MS. This method is more expensive than the other two methods, but it provides the most accurate results.

Colour of NPs is due to surface plasmon, but the colour of semiconductor is due to change of band gap.

I hope the following literature could answer many of your questions regarding carbon dot. Read this literature carefully and then decide which way to go

You are losing fluorescence after dialysis indicates that the fluorescence is coming out from molecular fluorophores present in your raw sample not your prepared carbon dot.

NaBH4 is strong reducing agent, and used for synthesis of nanoparticles fabrication on the other hand sodium citrate stabilizer and as caping agent in cases.

NaBH4 manipulation for titanium dioxide, Ag, Au , Pd and other metallic oxide nanoparticles fabrication.

Dear Yasmin Choaie, please tell which nanoparticles and applications you are dealing with. PEGylation is done for many purposes depending on the goal the NPs are intended to. If it is just for stabilization, PEG coating is enough, however if the NPs are for drug delivery, covalent grafting is necessary to increase circulation time and reduce erosion during circulation. In addition to that and according to recent studies there are two alternatives to PEGs with regards to biocompatibility and toxicity. Polyoxazoline and polysarcosine are more recommanded whenever it is to protect NPs for drug delivery, diagnostics, and so on.

Yuhong Mao

Although this question has already been discussed several times, but you have a contradiction with the usual results. Usually, the hydrodynamic diameter of a nanoparticle obtained by the DLS method is larger than by the SEM method due to the hydration of the nanoparticle. A nanoparticle material is needed to find out the reason for this result of the experiment.

Mohammad Kooti Sir, Thanks for your interest. Actually here the metal compounds that are needed to be converted to nanoparticles will be later subjected to molecular docking analysis with the protein of interest that's why I'm referring to them as ligands. Please guide how to use vesta for such conversion.

Regards,

Vinay.

The study of the interaction of nanoparticles (NPs) with proteins is of great importance due to its relevance in several fields including nano-biosafety, nano-bioscience, nano-biomedicine, and nano-biotechnology. an introduction and a discussion of merits of fluorescent NPs compared to molecular fluorophores, labels and probes, the article assesses the kinds and specific features of nanomaterials often used in bioimaging. These include fluorescently doped silicas and sol–gels, hydrophilic polymers (hydrogels), hydrophobic organic polymers, semiconducting polymer dots, quantum dots, carbon dots, other carbonaceous nanomaterials, upconversion NPs, noble metal NPs (mainly gold and silver), various other nanomaterials, and dendrimers. Another section covers coatings and methods for surface modification of NPs..

Dear all, there are various inoganic/organic salt precursors and synthetic routes to the preparation of ZnO nanoparticles, all with distinct final features of ZnO nanoparticles, in addition to the preparation conditions. Please have a look at the following documents. My Regards

DOI: 10.5772/intechopen.83338

I am also finding the same problem with Mn₃O₄ nanoparticles..

Micelle forming ability is dependent to your polymer physicochemical properties. Polymer charge and net charge in solution is important. Also HlB is a important parameter.

Furthermore you can use hhydrophobic fluorescence probes such as pyrene for study of micelles in your study. Block copolymers also without charge may generate micelle or reverse micelles in solution.

A book entitled as micelles , monolayers and biomembrane from M.N. jones is useful.

Thanks Ammar for sharing your own experience with us. Let me ask you if you use this for plants ?

Khetab Ullah The optimum temperatures for fungal growth were found to be between 25 and 30 °C.

Suraj Bamankar may be this article will help you,

Dear Eknath: P.S. I just read your statement "I want to Prepare polymeric nanoparticle (Anticancer Drug by using Polymers i.e. HPMC, Tween)." Here again the "Publications" section of RG is a good source of information. For example, I just came across the following potentially useful article:

Please check if the full text ofthis paper is available through your institution. Yet another interesting article is freely available as public pull text on RG:

Also please see:

As you can see, even more specific literature references can be easily accessed right here on the platform.

Lattice parameter of which one is high : Bulk and Nanomaterils?

Dear Arif

You are right, if magnetite is oxidized to Fe2O3, hematite form, it will become antiferromagnetic.

May be this will help

Sweta Satpathy

The tungstate ion is hydrolyzed to W (0H) 6 (this is a sol). Then it gradually turns into gel WO3 and xerogel with aging

WO4^2- + 2H2O = 2WO3 + 4H⁺

Pick up a dilute sodium tungstate solution. With dilution, an increase in the amount of water, the degree of hydrolysis increases. Apparently you took a concentrated solution and you have a photo with a mixture of sol and gel.

Dear Beatriz Dias Barbieri, to the best of my knowledge there is no standard protocole to do, either it is arbitrary or an experimental trials. Please check the following RG thread and documents. My Regards

If you require a minimum suspension viscosity, but the best dispersants for nanopowders are ethyl or isopropyl alcohols. To create low-viscosity water-based suspensions, add tensides (dishwashing detergent) to the water. For more viscous water-based suspensions, a polyvinyl alcohol solution or methylcellulose solution (wallpaper glue) can be recommended. The higher the viscosity of the suspension, the more resistant it is to sedimentation.

as per phase diagram of CaO-Fe2O3, mixed and heat in muffle furnace as indicated temperature

You may use an infusion pump for controlled addition at a programmable rate.

Filtering out is not a solution to getting the desired particle sizes. By doing so you are just removing the undesired part of the sample, not the root cause.

Probe sanitation is also a good option but that comes with the associated drawback of metal from the probe contaminating your sample and you may find a grey precipitate at the bottom of your sample after you centrifuge it .

for ZnO, Ethanol or DMSO or CH3COOH are best dissolve

Thank you Giuseppe Curro for your time. We moved on to spin coating after initially drop casting, the latter method followed at the time of my posting the question, which I did not mention.

The undulating patterns due to the interference phenomenon as you said is very common in my experience when one substrate is placed on top of the other and a transmission experiment is done. But I do not see it when only one substrate is used, as the nanoparticles are not in the form of a film on the substrate and do not cause multiple reflections at the interface.

We do collect a blank reference spectrum with quartz before we do the absorbance measurements in transmission mode.

For focusing, right now we only use a collimating lens after the light source, but nothing that would collect all the light coming from the sample and channel it into the spectrometer. Maybe I am not having enough of a sample to account for the light lost from the source to the spectrometer.

HI,

I have a thought but I am not sure it will work and if it worked if it has the end result you want. Now if you reacted FMN ligand with say KOH or NaOH you would get the negatively charged oxygen off the phosphorus. Now the problem I see is that the surface of the Ag NP should be negative. So you have two negative groups that don't want to join. So that said, there are mechanisms where one can take cationic polyelectrolytes and form bridges. My Phd Thesis,

reports on the use of polyelectrolytes and the use in different binding mechanisms. I have an achieved project folder with shorter articles as well that talk about this. Many have used cationic polyelectrolytes as a binder. This is well known in the literature. There are cationic and anionic versions. Polyelectrolytes are widely used in investigations with cationic polyelectrolytes binding to cellulose. In concept you could use say CPAM (cationic polyacrylamide) to bridge FMN and the Ag NP. Now that might not be what you are looking for but I think it is possible to do.

Now one complication is that this will also create Ag NPs that are bridging each other so you will get not only single NPs but complexes where they are bridging with each other NPs forming like floc like structures through binding. The question is what can you live with?

There are other bridging compounds as well to try. I hope this gives you at least some ideas. But the main thing is I see this as a problem to bridge your FMN to the Ag NPs. Good luck.

Bath sonicator and vortex are widely used for this purpose

Dear Bhaskarjyoti Bodo ,

I presume you mean shifts of nanoparticles compared to ‘bulk’ ZnS.

For ZnS nanoparticles it has been demonstrated that the absorption of the surface states becomes more intensive and gives blue shifts in absorption spectroscopy. This is basically explained by the fact that the contents of the surface states increase as the size of the particles decreases.

‘Normally’ the broad and Stokes-shifted emission band in PL spectroscopy is attributed to the so-called trapped luminescence arising from the surface states and becomes more intensive and shifts to the blue as the size of the particles is decreased.

See for nice and rather complete overview (and references to the above description for ZnS):

Yoffe, A. D. (2001). Semiconductor quantum dots and related systems: electronic, optical, luminescence and related properties of low dimensional systems. Advances in physics, 50(1), 1-208.

As said by others it depends on what you mean by Red shift (compared to what) but the following paper described PL intensity spectra plotted against wavelength for different excitation wavelength (340-420 nm) and a redshift has been observed with increase of excitation wavelength which according to the authors “may be due to different contribution of excitonic emissions and their phonon replicas”, see for details:

Mukherjee, A., & Mitra, P. (2017). Characterization of Sn doped ZnS thin films synthesized by CBD. Materials Research, 20(2), 430-435.

Hope this helps you somewhat further.

Best regards.

Sometimes polymers have low molecular weight since it is inherent of their nature and mostly if they are not synthetic. Some nano-particles such as graphene, helps generating a kind of "cross-linking" in the polymers transfering to it mechanical properties desired.

@rowaidah, if soluble the drug will be in the organic phase as solution, no matter the centrifugation.

If the particles settle down, the you have more likely microparticles.

Try to filtrate them through 0,45µm. I am sure, they do not pass.

Yes. It's easy and more active

Thank You, Yuri Mirgorod for the article)

SEC is one possibility, if all are genuine nano (i.e. 100% < 100 nm).

Zeeshan Uddin

Zeta potential is not surface charge.

See this article:

Dear Amna

Why do you need to dry silver nanoparticles? If you want to use them, the silver nanoparticles are kept into liquid form to avoid aggregation. Once they are dried, it is impossible to make homogenous dispersion solutions. Hope it helps.

Xuhua

Dear Seung-Yeon,

I understand what exactly you are asking, I think my colleagues have missed your point. Before I can go into details you need to check couple of things. First what was your entrapment efficiency, how much BSA were you able to load into Christan nanoparticles. Secondly, have you checked the Solubility of BSA in your release media. As you know the drug release from the nanoparticles is governed by the partition coefficient and the solubility of your drug in the release media. If your BSA has a low solubility in your release media, then you won't able to see much of the drug release. The drug will favour to stay in the nanoparticles. Regarding nanoparticles solubility, this term is not 100 true, if you want to dissolve chitosan nanoparticles, there is an enzyme you can use that able to dissolve these nanoparticles and break down the chirosan polymer. For the drug release from the nanoparticles, there are many mechanism that the drug released from the nanoparticles. For example but not limited to, erosion , diffusion and other. To know which mechanism your polymer follows, you need to perform drug release and then do some release modeling, from that release profile you can find out which mechanism.

Why you need your nanoparticles to dissolve?

Regards

Ali

his article can be helpful:

You should consider bottom up approach, like Hydrothermal synthesis. You can get the controllable as well as uniform nanoparticle size. As a matter of fact you can even achieve size range of 2-10 nm i.e. Quantum dots.

For further reading:

S. I. Sadovnikov  and  A. I. Gusev, Recent progress in nanostructured silver sulfide: from synthesis and nonstoichiometry to properties, J. Mater. Chem. A, 2017,5, 17676-17704 .

Hope this helps. All the best.

Your polystyrene nanoparticles(NP) are carboxylated which would make them neutral at low pH because there's excess hydronium ions in solution. When you react it with a protein through EDC conjugation, the carboxyl covalently attaches to the amines on your protein. Depending on the availability of carboxyl groups on your NP and whether or not you optimized your conjugation process with respect to the concentrations of the NP, the protein or the EDC as well as the pH of the reaction, there could be available carboxyl on the NPs and some free unconjugated amines on the proteins that are already attached to the NPs. And depending upon the pH and electrolyte levels at which you store your NP - protein conjugates, the free carboxyl from one NP- protein conjugates could be attracted by a free amine from another NP-protein conjugate. When multiple such interactions occur, you get your aggregated NP-protein conjugates. How to avoid it? Optimize your reactans and reaction conditions that I mentioned above and then react the available excess carboxyl on the NP with a neutral molecule to prevent interactions with free amines from the conjugated proteins.

You can follow this article given below for controlling size of core-shell (Fe3O4@SiO2) nanostructures

I‘d suggest you to filter the nanoparticles and keep them slightly wet in an 0.1%-1% solution of ascorbic acid this will keep them reduced and stable in oxidizing environmen. If you need them dry I‘d suggest directly vacuum drying the Cu np with excess of ascorbic acid and storing them in a very small, airtight container

Dear brother,

If you are synthesizing nanoparticles through green nanochemistry, than use water as a medium for the synthesis of nanoparticles, which is more advantageous than ethanol.

After obtaining the nanoparticles in reverse micelles, verify their size on TEM. Maybe they have already been aggregated before adding TEOS, i.e. before getting the shell. Magnetic particles you apparently get from hydroxide. Perhaps you badly calcined it when you received the oxide.

This is interesting! You have to confirm the purity ZnO phase by XRD and EDS. If you sure that you were use high purity precusors and clean environment, colouring of the heated ZnO powder may indicate the presence defects which effect the electroninc, optical and even the magnetic properties of synthesized product. Therefore, these defects may enhance the absorption peak and shift it to higher wavelenghts UV-Vis spectrometer). I observed yollow colouring of my prepared ZnO nanorods.

please check out the article along with the thread below for more details:

Hi researcher,

You can use the lipid-based nano-biopolymers that functionalized with targeting agents such as monosaccharides, antibodies, folic acid, etc. in which smart nanocarrier actively target the mitochondria membrane.

Recommend Darius Arndt answer

what kind of bond is between the thiol and the surface of gold NPs?

if NPs capped with citrate, can thiol react with COOH?

It’s so easy to measure the surface charge of your particles by using the dynamic light scattering (DLS) device.

Single nanopaarticles can produce hundreds of ions

Subha Kandiyar we are washing in order to remove the un-reacted moieties and the loosely bound capping agent. So that the surface of our nano are free for activities

Increase the concentration of silver nitrate. Then washed your nanoparticles wit ethanol 2 times.

Use ethanol instead of methanol. Wash 2 time with ethanol.....after drying you will get powder for of AgNPs

You can hydrolyze starch or cellulose (cotton) and get water-soluble oligosaccharides. They will not be nanoparticles, i.e. solid dispersed systems. Hitosan is also a natural substance, but with a large molar mass. Therefore, it is not soluble in water and exists as a dispersion in water. Chitosan (oligosaccharide), for example with MM = 20, 38 kDa, is water soluble. Researchers offer polysaccharide nanoparticles consisting of chitosan (CS) and cyclodextrin (CD) derivatives. For this you need to conduct a complex synthesis. Amino groups are not responsible for imparting nanoform. The nanoform is given by the molar mass of chitosan. Amino groups interact with a proton in an acidic medium and give a positive charge to chitosan nanoparticles.

I will surely go through the link. Thanks for your cooperation mukesh.

they were aggregating*

hi,

A simplest approach would be to test thermal conductivity of a fluid under use which is as per your need/choice and compare it with the thermal conductivity of the same fluid after adding the appropriate metal/alloy nanoparticles. Usually the addition of such metal nanoparticles enhances the thermal conductivity of the fluid.Easy said than done. You need to optimized on many levels. An arbitrary choice for fluid and type of nanoparticle may give erratic results or may even cause degradation of the device under study. Just make sure you do the thorough research before you actually start mixing things together.

Regards

What is your reason for thinking you have 'gone wrong'? Many metal oxides will be positively charged at pH's around neutral or even alkaline (you don't tell me the actual pH). At acidic pH's (e.g. < 2) then magnetite will dissolve. At higher pH's, Fe(OH)₃ will precipitate. There is a limited pH range over which magnetite will not chemically interact with its surroundings. The major factor affecting zeta potential is pH.

If you have genuine nanoparticles (< 100 nm) then your colloidal suspension should be transparent (probably colored though) with no precipitation.

looking forward for more specific question. Thank you

If you will synthesize gold nanoparticles from 1 g of chloroauric acid, then you need to take a large excess of citrate. 1 g is 0.0029 mol of acid. Take a 10-fold excess of a quotation of 0.02 moles and you will get about 0.0029 moles of 10 nm gold nanoparticles. This is 0.57 g of gold powder. During the synthesis it is necessary to take the concentrations that are known in the experiment.

See attached figure.

Positive counter-ions first attach to the negatively charged particle, forming a rigid layer called the Stern layer. The particle continues to attract more counter-ions but now these counter-ions are being repelled by other counter-ions in the vicinity and by the Stern layer itself. This second region is called the diffuse layer and together, both layers are referred to as the double layer.

Surface potential is the electrical potential between the surface of the particle and any point in the suspending liquid. The slip plane is where the Stern layer and diffuse layer meet and it is here the electrical potential is called the zeta potential.

Basically, the higher the absolute value of the zeta potential, the more stable the dispersion (particles are repelling each other). To aggregate the particles, you can change the zeta potential by changing the environment of the particles (pH, ions present, ionic strength, etc.) or by modifying the surface of the particles directly (active surface agents, polymers, etc.). A rule of thumb to aggregate the particles is to bring the zeta potential to between -25mV and +25mV. Hope it helps!

More info:

Google search this pdf -> Zeta Potential : A Complete Course in 5 Minutes

A more basic tutorial -> http://www.colloidal-dynamics.com/docs/CDElTut1.pdf

Dear Grace,

You may have to use suitable surfactant or stabilizer to get uniform NPs. You need it to regulate the growth and final particle size of ur formulation.

Since you are planning to crosslink the surface of the NPs, perhaps u choose surfactant with structural composition that cannot interfere with the process. There are range of them available with different composition.

I think incorporation of surfactant or stabilizer is more critical in NPs synthesis than replacing the dichloromethane with acetone because the solvent can be use if appropriate surfactant or stabilizer is in corporated in the dispersion medium. Pls check the methodology in the attached article.

Remove PVP by dissolving it in water. Add water and centrifuge the nanoparticles until the PVP is removed.