Dr. Chandrasekaran,

A number of additional methods (beside AFM, TEM, and SEM) can be used to tell the changes of your biomass samples.  For example XPS can tell you the changes of chemical elements on surfaces.  BET analysis can tell you the changes of surface area of your particles.

Good luck

Maohong Fan 

Dr. Chandrasekaran,

A number of additional methods (beside AFM, TEM, and SEM) can be used to tell the changes of your biomass samples.  For example XPS can tell you the changes of chemical elements on surfaces.  BET analysis can tell you the changes of surface area of your particles.

Good luck

Maohong Fan 

Dear Arun,

I totally agree with Dr.Fan and Dr.Khoshnevisan. AFM would probably be the best option if you want to visualize surface topography especially if you looking for patterns like columnar structures or troughs etc on the surface of your sample. Moreover different modes of AFM (i.e. contact, non-contact,tapping,  etc.) provide flexibility to suit different types of samples. Virtually any sample can be analyzed using AFM and also it is performed at ambient temperature and pressure (so most suitable). 

(In case you want higher resolution, you can go for STM of your samples, but it needs conducting samples and to be operated under vacuum unlike AFM.) 

SEM is also very useful, but sometimes there is problem of surface charging etc. particularly if your sample is not very conducting and the contrast might not be very good. In that case generally gold coating is done which might affect surface morphology to some extent but it's acceptable.

And also if your sample is in the form of a thin film (although powder also works), and you want to analyse surface chemical composition (which might sometimes also turn out to be overall composition of sample), oxidation state of elements etc. you can go for XPS of your "pre-treated" and "treated" samples.

Hope that helps.

Srujan

Thanks Dr. Fan and Dr. Khoshnevisan. 

The real problem I'm facing is my sample is soft, polymeric and non-conductive. As Mr. Srujan said, sometimes I could not get good quality of images in SEM. Also, I could not go for AFM analysis, because it will give just an alternate bright and dark rows. (crest and trough pattern). But, I need to see the demolition of the cell wall of my samples. 

Hey Arun. You should specify what surface you are talking about. The SEM, TEM, AFM and STM is used to characterize the morphology and characteristics of solid surfaces which are conductive. 

So I presume that you are talking about changes in the structure of the cell wall of a plant cell before and after a specific treatment.

You could use Fourier transform infrared spectroscopy (FTIR) to characterize the chemical structure changes. FTIR spectra would show the types of bonds present before and after treatment. 

Hey Arun, for clarification -- You did biomass pretreatment and want to characterize the biomass before and after pretreatment, right? Then one characterization you can perform is through XRD to get some indication of changes in the crystallinity of your biomass. If biomass dissolution and hydrolysis were successful, you will observe some changes in XRD patterns. For images, we did e-SEM before instead of SEM or TEM because these techniques would require you to dry your samples. We believe that dried samples will not actually give you an accurate physical appearance of your biomass in contrast to e-SEM in which wet or moist samples are possible to be inspected. You can check some of our papers for details. Composition-wise, FTIR (this may not be too sensitive) and XPS can be performed. Good luck to your work. Cheers!

I would use AFM if SEM/TEM are not possible for some reason

Thanks for your answers. 

I believe the best method for you is confocal microscopy (if you do not need high magnifications). You can observe wet specimens; in contrast to SEM you can observe specimen submerged in a liquid (in ESEM you can see only surface of a liquid). You can have 3D reconstructions. 

Hi

For bigger samples (area more than 1um) you could use (C)LSM (confocal)laser scanning microscopy. Unfortunately you will need to use some fluorescent marker. Using LSM you can make 2D and 3D scan (as Vladimir Dusevich said). In my opinion for surface topography you can apply AFM (consider mode which will be good for your samples: contact, non contact, tapping).

All the best

Hi Arun,

I would suggest measuring porosity or water retention value of the material besides the surface characterization. Furthermore, there are methods for determining surface areas of cellulose and lignin based on specific dye adsorption. If you are interested please see more info from the articles:

http://www.researchgate.net/publication/232277508_Cellulose_accessibility_determines_the_rate_of_enzymatic_hydrolysis_of_steam-pretreated_spruce/file/d912f50c84d66879d4.pdf

http://www.sciencedirect.com/science/article/pii/S0960852414009274

Good luck with your work!

Article Cellulose accessibility determines the rate of enzymatic hyd...

You can do AFM analysis, as it can directly give the roughness values before and after of the treatment.

Thank you for your answers. 

hi. for the charactier of the pretreatment row, i think it's necessary for proving the sample that could be representative no matter what after or before pretreatment. so, as my point, CLSM and GTA and FI-IR and XRD are suitable for the job,respectively. but, for the NMR-CH, some paper reproted that this method can analyzs the change of radicals, is not enough take the representative for the analysis of the characteristics of the sample because of the small volume of sample.so does AFM.    

good lucky for your job.