Surface Functionalization - Science topic

Uttam Gupta

You need to use S-benzylisothiouronium chloride. This reagent forms insoluble compounds with sulfate and sulfoether groups. The benzyl radical will impart hydrophobicity. If it is not available, use any cationic surfactant.

You want to use EDC NHS to make N acyl

pyrrole. These exist, but are they commonly prepared by N acylation? The pyrrole N lone pair is part of aromatic system so it has reduced nucleophilicity….

you are showing pyrazole structure - this may be different since one N has a non-aromatic lone pair- but it may acylate and isomerize!

I am not sure if APTES functionalization has a great effect changing nanosize to microsize. This may happen if you have low charges of nanoparticles, then the repulsion of every particle is low. Consequently, aggregation may happen.

You could measure the zeta potential first.

Several studies mentioned that using dry toluena for APTES is better for functionalization.

Thank you for response Federico Svarc

Damn, Matze I saw this thread rn. How funny it is that I am actually measured surface coverage using XPS of an acid on ITO. The article will be online in a couple of months...

There's another method: it's from electrochemistry actually. So you gotta run a CV of your SAM and calculate the total electrochemical capacitance by integrating the CV curve... Then you could actually calculate surface coverage actually...

Check this paper: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2885823/

In general the electrochemical capacitance is related to molecular packing density by the equation:

Density = Q/nFA (Q is the electrochemical charge which can be calculated from total current and scan rate), F is Faraday const. A is the electrochemical surface area exposed to the solvent.

Just use the SAM on ITO. Run the blank test on ITO and on this SAM and calculate. Please take note that blank ITO shall contain lots of In(OH)3 and oxyhydroxides InOOH type species ....which can't be removed fully even with sputtering...so the electrochemical area of the blank doesn't correspond to 'nothing on surface'. Your sample response will be representative of your SAM density though! Usually upon SAM formation these hydroxides/impurities leach out quite substantially (if not all).

Dear Dr.Sulin Choo,

I used the filtration way for this matter.

It was an excellent way to get the optimum pH value.

It seems the linearization is accomplished by replacing x1, for x1^2. And separately by replacing x2, for x2^2 & x2^4.

In this way, the surface function is linearized about the origin (0,0), it means we can find f1(x1,x2)=a*x1+b*x2, whilst a and b are calculable in terms of the algebraic parameters, k and c.

But my question transforms to another level. How, we can find a compact algebraic expression for f1(x1,x2), and f2(x1,x2), close enough to the origin. This algebraic expression, need NOT be necessarily linear (it could be a nonlinear function).

1--How to find another compact analytical expression equivalent to f1(x1,x2), f2(x1,x2)? (with fair accuracy)

2-- Is it possible to find an approximation near the origin (0,0), for f1(x1,x2), f2(x1,x2), as a function of only one of the two variables (either x1, or x2)?

Regarding the second synopsis, I am to cite another ResearchGate question linked below:

However, the gist of the idea in this link is not clear to me.

You can check the paper below for more details:

Regards,

K

Santosh K. Tiwari Thank you for responding I'll look into these

OK, so you just want s drawing with maybe a simple optimization? You can use most structure editors like Avogadro, Molden or others to draw and perform a simple force field optimization:

This might help:

It depends on your target protein. NHS will attach the protein via amine groups ( amino acid Lysine in the protein). This is a very efficient and targeted reaction and lysine itself offer a spacer between the microbead surface and the protein. Epoxy groups are usually used to link with hydroxyl groups on the protein (amino acid Tyrosine) though it can also be used to link thiol, and amino groups on the protein. So, the choice depends on which amino acid in your protein you want to use and what impact it will have on subsequent use of the microbeads

Chemical bonding changes physico-chemical properties and the mechanical properties also change! It's important that can it be observed/measured at very small scale?

If you are trying to detect a surface functionality of a film with monomolecular layer equivalent, I doubt if you can see any surface functional groups using FTIR. Using a thin film. Using a thin (1 mm thick) Si ATR crystal, you might be able to detect one of the strongest absorbing groups, carbonyl. Using special samples, conditions and/or techniques, you might be able to study the surface of polyethylene. See the papers shown below. We used a PE fiber for the first paper, but you might be able to use a very fine PE compacted powder as well. Note that when you obtain the diffuse transmittance spectrum, you will not be able to see a spectrum in the same manner as in usual transmission technique. The spectrum would be at the bottom of the screen. You need to expand the spectrum in the y-axis. The second paper utilized a very special technique called surface electromagnetic FTIR spectroscopy and detected carbonyl groups in much less than a monolayer equivalence.

"Diffuse Transmittance Spectroscopy of Polymeric Fibers," A. Taboudoucht and H. Ishida, Appl. Spectrosc., 43, 1016 (1989).

"An FT-IR Study on Interfacial Interactions in Ethylene Copolymers/Aluminium Laminates in Relation to Adhesion Properties," L. Ulren, T. Hjertberg and H. Ishida, J. Adhesion, 31, 117 (1990).

Kapton (polyimide) is effectively the most widely used polymer if you want to use it as a substrate. However if you are looking for an interstitial layer that you can deposit and then peel of, Parylene may be better. It can be deposited by thermal evaporation, resists the temperatures associated with most classical microelectronic processes and will provide a very smooth surface if deposited on glass or Si wafer.

Flexdym is a great alternative to PDMS, which does not require O2 plasma bonding.

The fabrication protocol is easy to use and only 2-15 minutes long, depending on your application. And because Flexdym is a thermoplastic, it can be recycled and re-molded. Check it out at https://eden-microfluidics.com/

Graphene oxide is manufactured typically by modified Hummers' method. There are a number of conditions but basically it uses oxidizing compounds to chemically oxidize graphite which is near perfect fused ring 2-dimensional sheet stacked up with many layers. Upon chemical oxidation, many defects (chemical functionalities) are inserted in these perfect lattice and weakens the interaction between individual sheets, which allows to separate each sheet. Some of those functionalities are internal epoxy group, phenolic group, and carboxylic acid groups. When you say "graphene" oxide, you imply a single sheet as graphene is a single sheet of the graphitic layers. One unique aspect of graphene oxide is the presence of chemically reactive functionalities on the basal plane in addition to the edge plane. This makes difference from typical silicate nanofillers which has available chemical functionalities (typically SiOH groups) only at the edge plane. Those that exist on the basal plane is embedded deep from the surface and cannot form covalent bonds with external chemicals, though it might weakly form hydrogen bonds. As a result of the insertion of chemical defects on graphene, graphene oxide's reduces electrical conductivity drastically from graphene, though the majority of the mechanical strength is maintained.

Expanded graphite is not a single layer. It is manufactured by inserting concentrated sulfuric acid into graphite and the sulfuric acid intercalated graphite is suddenly heated to a high temperature. This action will expand the d-spacing of the graphite and will be easy to further expand upon certain applications, such as a flame retardant additive. Since individual layers are still aggregated, the expanded graphite is not regarded as nano fillers nor it has the ability to reinforce polymer matrix like graphene nano filler since the aspect ratio of the filler is so small. Since concentrated sulfuric acid is used (and sometimes with nitric acid mixed), it is natural to expect the chemical reaction with the graphite layer by inserting sulfonate groups and carboxylic acid groups in a similar manner as the chemical surface treatment of traditional carbon fibers by those chemicals (though commercially, carbon fibers are oxidized by electrochemical means). Again, by inserting these chemical groups, the electrical conductivity reduces significantly from the pure graphite.

Thus, the similarity of graphene oxide and expanded graphite is that both have chemical functional groups inserted into the graphitic lattice with the corresponding chemical groups used to treat. The main difference is that graphene oxide is typically a single or few layers of oxidized graphene (nano fillers) whereas expanded graphite is a stack of so many layers and is still a usual filler size (many micrometers or even millimeters in both thickness and length. It is a usual filler size). Discussion of d-spacing is meaningless for graphene oxide (ideal graphene oxide has only single layer and thus usual layer-to-layer distance does not exist. If you are interested in the thickness of the layer, it is close to 1 nm). On the other hand, the expanded graphite has so much breadth in d-spacing and again it is almost meaningless to discuss about it.

The term exfoliated graphite is seldom used, but the meaning of this corresponds to graphene. When you exfoliate graphite, each layer is so distributed without the position alignment (random) and each single layer is distributed without any preferred position. This is the definition of graphene.

Nissem Abdeljelil

It's very easy to fix a silver precursor (ammoniacal silver nitrate is often used) to a substrate and reduce in situ. Supported metal/metal alloy catalysts are a good example. Here the size and loading of the metal can be controlled relatively easily. You could also try buying in one of the silver witchcraft recipes and absorbing onto a surface but here the concentration is likely to be very low (ppm) and not controllable. Further, making your own is probably much cheaper and you'll learn more. For an overview take a look at this webinar (registration needed):

Silver colloids and invisible ink

... and the even more general:

Metal colloids - their preparation, application and characterization

Be aware that the active bactericide is Ag⁺ and not Ag⁰. The surface of all 'silver' materials in air or water is always fully oxidized and it's the solubility of the nominal oxide that confers the properties.

Thank you for answering me Marcos

Best regards

Dear John,

The use of antibacterial and antimicrobial cleaning products – combined with the over-prescription of antibiotics – may produce strains of bacteria that are resistant to disinfectants and antibiotics.

The overuse of antibacterial cleaning products, including disinfectants in the home, may be producing strains of bacteria that are resistant to multiple antibiotics. Bacteria that are resistant to many antibiotics are known as multi-resistant organisms (MROs). These cleaning products are no more effective at preventing infection in the home than good personal and household hygiene using ordinary soap, warm water and plain detergent.

Most bacteria actually help humans. When you use antibacterial or antimicrobial cleaning products, good bacteria are also killed. This could be harmful if the ratio of good to bad bacteria is disturbed, and bad bacteria get the upper hand.

Solution:

The solution: permanent antimicrobial coating of surfaces. While most EPA and BPR-registered active ingredients for hard surfaces are non-toxic, their promised effects on odor-causing bacteria and mold growth (mold control) leave a lot to be desired. Antimicrobial surface coating is much helpful here. Ity may prevent contamination and subsequently disease as well.

Ashish

Functionalized nanocrystalline cellulose with antiviral element or oxides can be used in fabrics and mask.

You need a high or medium pressure mercury lamp and should exclude oxygen (either cover with glass or use N2). Also, not sure what you are trying to graft but acrylates work best. Benzophenone is a type II initiator (sensitizer) and works best with a co-initator such as an amine. Other initiators (Type I) such as Darocure 1173 may work better.

Zeeshan Uddin

Zeta potential is not surface charge.

Hi Manuel.

Oxirane ring can reacts with alcohol via etherification reaction. But it needs catalyst such as tertiary amine (triethylamine and etc.). Also, it easily reacts with amines.

Relating to your synthesis , may be the ethanol (solvent) participate in oxirane ring openning reaction.

Also, higher temperature im more favorable.

Don't use solvent or If you need solvent, change it.

Good luck

Yes..!

"GQDs undergo self‐quenching in the solid state, like organic molecules ascribed to excessive resonance energy transfer (RET) or direct π–π interactions"

it correct.

U can use any inert Film former for it.

Hi. I have been preparing PNIPAM polymer brush functionalized gold surfaces for quite a while now and noticed that even months after the preparation the thermo-responsive property is preserved, so my suggestion that storage in air is fine. However, before attempting some serious experiments with the PNIPAM functionalized surface, ensure that the material was hydrated before, so that the swelling/collapse property is re-established as it should.

liquid ammonia

As you know, NaOH is stronger base than Na2CO3 and both are stronger than NaHCO3. If a base is strong it can neutralize all the acids even very weak acids like phenolic but the weak bases can not do so.

Keep in mind that zeta potential is not a measure of the surface charge of the particle. It is a measure of the electrical potential some distance away from the surface. Adsorbed species (e.g., ions) shield the charge. In some situations it is even possible to have a zeta potential of opposite sign to that of the charge at the surface of the particle.

Yes, in my opinion the shape and surface area affect grafting density which induce mushroom or brush formation. In addition, it also depends on the interaction with solvent, molecular weight of the PEG, and functional groups.

This article may be useful to develop alternative coating on basalt fibers

I agree with Omar.

The homogeneous formation of the nucleus of a new phase is observed when there are no surfaces in the system on which the formation and growth of the nuclei of a new phase occurs at a sufficient rate.

The heterogeneous formation of the nucleus of a new phase is observed with the introduction of the seed of the substance of the new phase itself or of a substance close to it in structure and properties.

You give an example of a heterogeneous formation of a new phase. Therefore, the surface of the old phase will affect the formation of a new phase. Particles of metals are hydrophilic. Therefore, the hydrophilic old phase will affect their formation. The hydrophobic phase will affect much less. Of course, one cannot exclude another interplay of the chemical structure of both phases.

The tissue culture media contains Phenol red , which turns yellow in acidic conditions and purple in basic conditions.

The only explanation is that your PVDF membranes are releasing a basic chemical into the media. Your membranes will need further treatment to remove this chemical tha tmust be present following functionalization.

Thank you for the help, it seems that using pre-modified PE is the only possible solution then!

See

Thank you so much - Allan! Your comments are very helpful to us.

Matt Jackson

Thanks a lot for your detailed answer

Our method is same as here-

As suggested by you we are exploring different blocking buffers, starting with the ones used with western blotting.

The distance between chromophore and gold in this case is very small, therefore, quenching should be expected. But this is not the only reason which would explain that you do not observe much fluorescence here. In best case, there is kind of monolayer of dye molecules on the gold surface. The distance between dye molecules in (more or less dense) monolayer is small, so concentration quenching may be expected on the one side. On the other side, the total amount of dye in the observation volume (with a thickness of at least couple µm) might be too small to expect a bright fluorescence. In worst case, there is simply no surface functionalization - having just a thiol group is not enough to form a stable and densely packed layer. In any case, the dim light you are seeing might be just due to scattering, which increases with the surface roughness.

Are you following somewhere published procedure or trying your own? Having something like FITC-(CH2)n-SH (or, in general, any few nm thick sublayer between gold and dye) should greatly improve fluorescence.

You probably can improve it my spraying some ethanol on the surface prior to fictionalization. I usually dip it in ethanol bath for 5min then nitrogen blow dry my surface, it works for me. However, my application is different with what you are looking for...

Hi Anna,

Thank you very much for the reply and recommending reference articles. They have proved to be helpful in a great way.

I am following "Washless layer by layer assembly" protocol developed by Prof. Yuri Lvov and colleagues. I have two different HA (Mw.200 Kda an 1000 kda).1000 kda HA makes NLC suspension thick and viscous if its used for layer by layer assembly. With 200 kda HA at 1 mg per ml concentration in a buffer instead of 0.5 M NaCl, I have been able to achieve desired results and am engaged in further modifications.

I have a question/doubt

1. Can we achieve D+ mannose coating on nanocarriers using layer by layer assembly? Can it be coated as outermost layer, because I think as mannose is a carbohydrate molecule and have affinity for water, it may get eroded or can get dissolved when coated as outermost layer over the period of time.

We performed this reaction for graphene oxide under dry conditions and resulted in a desired product.

TEA is a strong base in aqueous solution. Additionally to activation of existing silanols, it could activate splitting of siloxane surface groups by H2O to give more surface silanols.

Along with the specific surface area, the nature of the surface is important for the catalytic activity of carbon. Some reactions may occur with the presence of oxygen complexes (alkylation, hydrolysis, esterification) on the surface, others in the presence of dissociating groups (H-B exchange, isomerization, hydrogenation) or surface active centers (dehydration). There is a direct correlation of the catalytic activity of oxidized coals with the amount and acidity of surface proton donor groups. With the presence of oxygen functional groups on the surface of carbon materials, as a rule of acid nature, not only catalytic, but adsorptive and oxidizing properties are associated. The type of functional groups and their acid strength depend on the type of oxidizer and the conditions of the oxidation process. Nitric acid, hydrogen peroxide, as well as permanganates and bichromates are most often used as oxidants.

Hi Afiq,

You can make electrochemical desorption of 11-mercaptoundecanoic from the CE. The electrochemical desorption can be done by sweeping the potential between 0 to -1.4V in 0.1M KOH solution. You should optimize the potential window.

Good luck

Hi Fahad, I think you should examine the fluorescence properties of individual surface bound fluorophores before doing FRET.

Dear Abhijeet, As per my knowledge ultrasonication can reduce the size of GO sheets and during that time it may break the chemical bond between the graphene layer (-C=C- backbone) and the oxygen containing functional groups. But, complete removal of functional group may not be possible. Further, you have to keep in mind one thing that excessive ultrasonication will reduce the size drastically. So, the materials property will change a lot.

For example: https://www.sigmaaldrich.com/materials-science/material-science-products.html?TablePage=119470654

If you need a very clean process you can use laser ablation by UV pulsed laser

X-ray Photoelectron Spectroscopy is by far the best tool for this kind of job in my opinion.

You do not need ultrasonication for silanization reactions to occur. Perhaps you are only helping in nanoparticle dispersion and the created heating will only accelerate the condensation process.

Well, hydrodroxymethyldisiloxane HMDSO is evergreen precursor for superhydrophobic layers deposition. Organosilicon nature of plasma deposited HMDSO guarantees the superhydrophobic nature. Then you can play with the roghbess of the coating and by increasin Ra you obtain higher WCA. The presense of amine group decrease the superhydrophobicity and WCA, because NH2 Is hydrophylic group. Look to some of my papers. APMS OR APTES  are not good precursors for superhydrophobic layers deposition. The addition of fluorine will increase WCA  for sure but I have concerns regarding the toxicity of such precursors.

I have some thoughts. However I need to understand more first. What reference information do you have for the method you are using now? Has it been successful for someone else? How do you know that your loading of dye on the particle can be increased? What independent test have you done to confirm that you are not already at full coverage?

In general, with all else being equal, IR intensity is proportional to the number of absorbing species per unit volume. In a perfect case, an increase in IR absorbance means that you have increased the concentration of the species. The concerns are that samples must be normalized to exactly the same state. Any change in properties such as sample thickness, reflectivity, or bulk density will also affect IR intensity. A required first-order approach to compensate for this is to normalize the spectral intensity against an internal calibration standard and to perform other characterizations to complement the IR.

In summary, a simple answer is not possible from general principles.

My subsequent recommendation is to do a literature search for IR studies of comparable materials to what you have. Review how they address your questions. Someone with the requisite specific background may also chime in here to point you in the proper direction.

Yes, the stober process. Good luck

You may want to check this somewhat related discussion: https://www.researchgate.net/post/How_to_achieve_100_removal_of_oleic_acid_capping_agent_from_nanoparticles_surface

You have to work in various temperature as an one of your parameters to find optimum conditions that gives you better participation

Hi Miguel, -COOH surface functionalized nanoparticles are more useful that you think.

The  -COOH surface can be modified by  ethyl(dimethylaminopropyl) carbodiimide (EDC) and though that you can couple organic and inorganic compounds with primary amines. The possibilities are endless.

i think for this kind of attachments and bonding between functional groups we can use  coupling agents such as DCC/ DMAP or EDC/NHS in a controlled condition. as you know thiol groups have a good ability to gold and you should activate gold nano particles by a double functional molecule that one of them should be thiol for attach to gold surface and another can be OH,COOH or NH2 . anyway you should attach the polymer to activated gold nanoparticles.

Hi Arnab,

I know the charges of O and H from CLAYFF which are -0.95 and 0.425, respectively. However, when they are in combination with C, I suppose, the charge redistribution will occur and charge on C will no longer zero. Are you saying, I can calculate the charge of C using QEQ fix method in LAMMPS?

Confocal microscopy would be appropriate tool.

Thanks for your guidance. Indeed, my sample is made up of  Fe3O4 nanoparticles, functionalized by 2-aminophosphonic acid and polymer is poly vinylcaprolactam with ester end group. I am doubtful about addition of base or acid to the solution of nanoparticles and polymer because I don't want the polymer to be hydrolyzed.

Use methoxy-PEG-OH, i am not sure if the oxidation will affect the backbone of the peg molecule. Give it a try. 

Hello, 

If your QDs are surface derivatized with carboxyl groups, their solubility should be enhanced at high pH. (at least a couple of units above the pKa of the carboxylic acid bound to the surface of the nanoparticles.  They may take a while to dissolve if they come from a powder form. This is because they may be aggregated into lumps bound by hydrogen bridges formes among carboxyl groups of particles in near contact.

Try dissolving them at the highest pH that is safe. Use a strong base like 1 mM of NaOH. If they disolve then lower the pH slowly until they precipitate out of solution.

Ion exchange

Thanks Omar Gonzalez, I have earlier tried Ab conjugation to glass slide using TEPSA (3-(TRIETHOXYSILYL)PROPYLSUCCINIC ANHYDRIDE)  which has silica group and binds to glass via Si-O-Si linkage and then carboxyl group of TEPSA binds to Ab via carbodiimide chemistry. But right now not having TEPSA so was thinking to do the same using TGA . But have not tried with APTES and glutaraldehyde; will look for this one also. 

You can selectively protect the e-amino group of lysine (e.g. with Boc or another carbamate protecting group) in the presence of an excess of Cu2+ (the alpha amino and carboxyl group form a bidentate ligand to the Cu2+). Please consult a couple of papers for exact reaction conditions.

I appreciate the response however I am not finding that publication could you post a link?

Thanks Jose. perhaps, I will try silica coating at first.

thank you for your answer

Dear Minh,

the adsorption of gold nanoparticles on aminosilanized surfaces is based on electrostatic attraction of negatively charged AuNP on a positively charged aminosilanized surface. Thus, if your AuPt-NP are as well negatively charged it should be no problem to deposit them on the aminosilanised silica. You could check the charge of the synthesized particles by measuring the zeta-potential of the NP-solution and then decide if adsorption would be successful.

Kind regards, Corinna

This is an excellent question! Many researchers claim a complex covalent immobilization without giving any evidence. Particularly, aminosilanized surfaces are extremely sticky towards proteins: They bind proteins non-specifically, irrespective the covalent step works or not. To my knowledge, there is no simple way to distinguish strong non-specific from covalent immobilization. Some proteins might be eluted by SDS and or high-salt conditions. The most accurate way would be the cleavage of the protein from the surface, eg. by a high-pH solution, and subsequent analysis of the proteins by digest and LC-MSMS. However, this is very laborious.

For microarrays on glass slides, we prefer epoxysilanes which do not show such extreme non-specific binding. Unfortunately, this approach needs more time. High-salt conditions often improve this coating.

If you only want to quantify the amount of immobilized protein (irrespective of the mechanism), I would suggest amino acid analysis, which is sensitive and quite accurate, in contrast to most other protein detection methods.

I not completely understand, but CB is hydrophobic sicut ibi. Perfluorinated CB is superhydrophobic

Dynabeads available from Thermo can come with a range of different functionalised surfaces, including streptavidin.

Usually basic dyes are preferable for your method

As your contact angle for water has increased this definitely implies some kind of modification has occurred though not sufficient to repel the alcohol mixtures.

It is a simplification but in order for your surface to repel alcohols you need the surface energy of the polymer to be below that of the alcohol mix.

If you are measuring a surface energy ~80 degrees with water this would imply your surface probably has a surface energy of between 30 & 40 mN/m (use Owens-Wendt analysis with 2 or more test liquids if you want a more accurate SE value).

However, alcohols often have very low surface tensions (20-30 mN/m) compared with water (72 mN/m) so they will still wet the surface - you are most likely to succeed using fluoro-modified silanes or polymer coatings - as suggested above. In particular, long alkyl-chain fluoro-modified silanes often have very low surface energy values. A problem with fluoro modified polymers is that they are by nature Teflon-like (i.e. non-stick) and will not adhere well to your polymer without bridging groups, etc.

The procedure of Abhishek is a good example of "know-how" and will work quite well especially for the basic APTES. If you keep the mechanism in mind (siloxane publication) multiple other ways will also lead to the goal (You need water and catalyst and a thin primer layer). I suggest using a less toxic, residue-free cleaning procedure (like H2O2/H2SO4) and a gase phase siloxanisation (acid surface and humidity works quite well) This a very simple, fast procedure using a desiccator, silane, reduced pressure and an (acid activated or a new) cleaned wafer surface, SiO2 (and atmospheric humidity). I also published some influences of "dry"(new) and "wet"(acid surface) preparation using APTMS and APTES resulting in m-APS.

The liquids used homogenization step are accelerated the formation of BaTiO3 dependent on the O-H bands of the liquids structure. More O-H bands increased the density of the calcined powders, and improved the microstructure of sintered BaTiO3 ceramics. The density of the calcined powders is 4.67, 3.66, and 3.49 g/cm³ for the water, methanol, and acetone respectively. X-ray Diffraction (XRD) and Raman spectroscopy analysis were verified the structure of BaTiO3. The differences of the microstructure are clearly shown that the micrographs of sintered pellets by Scanning Electron Microscopy (SEM). Depending on the liquid, the process led directly to normal and abnormal grain growth of the sintered samples.

https://www.researchgate.net/publication/311977968_Accelerated_formation_of_BaTiO3_ceramics_with_mechanochemical_processing_in_different_liquids 

This formula does not look correct to me. Assuming 0% weight loss for nonmodified particles would give you 1 as a result.

For surface coverage you should know the size of your nanoparticles to calculate the surface area. From the weight loss and the residual mass, measured by TGA, you can calculate the molar amount of ligands and the total surface area. This will give you then a surface density (molecules/area).