Tapping mode atomic force microscopy of scleroglucan networks

A. K. Vuppu, Antonio Garcia, C. Vernia

Research output: Contribution to journalArticlepeer-review

47 Scopus citations


Tapping mode Atomic Force Microscopy (TniAFM) has been used to study the fungal polysaccharide scleroglucan deposited from aqueous solution and dimethyl sulfoxide (DMSO) onto a mica surface. The solutions from which the microscope samples were produced were prepared by first dissolving the solid scleroglucan in 0.1M NaOH, then neutralizing the solution with HCl, followed by dilution to the required concentration in either water or DMSO. It was found that from the aqueous solution described above, scleroglucan forms networks. Based on a comparison of the denatured-renatured and aqueous solution samples, nehvork formation is due to the imperfect registration bet\veen the chains fanning the triple helices. The relatively large stiffness of the scleroglucan triple helix is also assumed to contribute to the formation of the extended netw-orks. The triple helix diameter was measured to be 0.92 ± 0.27 nm, which is in the same range as that obtained by other researchers using similar techniques. Denatured scleroglucan, deposited from DMSO onto mica, forms a web-like layer on top of which there are sphere-like structures. These morphologies are believed to be due to triple helix denaturation yielding highly flexible single chains in DMSO, which results in coiling and web-like dense packing of scleroglucan upon deposition onto mica. Most interestingly after addition of water to the samples deposited from DMSO, some of the chains can be renatured into short, stiff rod-like structures which are similar to the structures observed by other researchers. The imaging data for aqueous solution deposition can be analyzed by plotting maximum end-to-end distance versus the perimeter of the nehvorks deposited onto mica. This yields a Flory-like exponent of 0.67, which is almost similar in value to that obtained by other researchers for linear structures of scleroglucan but less than that expected for a polymer chain following a self-avoiding walk (i> = 0.75,) model on a Mo-dimensional surface. The fractal dimension that can be used to characterize the nehvorks was determined graphically to be 1.22 ±0.06.

Original languageEnglish (US)
Pages (from-to)89-100
Number of pages12
JournalBiopolymers - Nucleic Acid Sciences Section
Issue number1
StatePublished - Jan 1 1997


  • Denaturationrenaturation
  • Fractal dimension
  • Scleroglucan networks
  • Tapping mode atomic force microscopy

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Biomaterials
  • Organic Chemistry


Dive into the research topics of 'Tapping mode atomic force microscopy of scleroglucan networks'. Together they form a unique fingerprint.

Cite this