Revealing the Structural Organization of Gamma-irradiated Starch Granules Using Polarization-resolved Second Harmonic Generation Microscopy

Ming-Chi Chen; Indira Govindaraju; Wei-Hsun Wang; Wei-Liang Chen; Kamalesh Dattaram Mumbrekar; Sib Sankar Mal; Bhaswati Sarmah; Vishwa Jyoti Baruah; Pornsak Srisungsitthisunti; Naregundi Karunakara; Nirmal Mazumder; Guan-Yu Zhuo

doi:10.1093/micmic/ozad058

Revealing the Structural Organization of Gamma-irradiated Starch Granules Using Polarization-resolved Second Harmonic Generation Microscopy

Microsc Microanal. 2023 Jul 25;29(4):1450-1459. doi: 10.1093/micmic/ozad058.

Affiliations

¹ Institute of Translational Medicine and New Drug Development, College of Medicine, China Medical University, No. 91, Xueshi Rd., North Dist., Taichung 404333, Taiwan (R.O.C.).
² Department of Biophysics, Manipal School of Life Sciences, Manipal Academy of Higher Education, Planetarium complex, Udupi Dist., Manipal, Karnataka, India.
³ Center for Condensed Matter Sciences, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Da'an Dist., Taipei 106319, Taiwan (R.O.C.).
⁴ Department of Radiation Biology and Toxicology, Manipal School of Life Sciences, Manipal Academy of Higher Education, Planetarium complex, Udupi Dist., Manipal, Karnataka, India.
⁵ Materials and Catalysis Lab, Department of Chemistry, National Institute of Technology Karnataka, Surathkal, Mangalore Dist., Karnataka, 575025, India.
⁶ Department of Plant Breeding and Genetics, Assam Agricultural University, Jorhat, Assam 785013, India.
⁷ Department of Bioinformatics, Dibrugarh University, Dibrugarh, Assam 786004, India.
⁸ Department of Production Engineering, Faculty of Engineering, King Mongkut's University of Technology North Bangkok, Bangkok 10800, Thailand.
⁹ Centre for Application of Radioisotopes and Radiation Technology (CARRT), Mangalore University, Mangalore 574199, India.
¹⁰ Center for Advanced Research in Environmental Radioactivity (CARER), Mangalore University, Mangalore 574199, India.

PMID: 37488816
DOI: 10.1093/micmic/ozad058

Abstract

Starch is a semi-crystalline macromolecule with the presence of amorphous and crystalline components. The amorphous amylose and crystalline amylopectin regions in starch granules are susceptible to certain physical modifications, such as gamma irradiation. Polarization-resolved second harmonic generation (P-SHG) microscopy in conjunction with SHG-circular dichroism (CD) was used to assess the three-dimensional molecular order and inherent chirality of starch granules and their reaction to different dosages of gamma irradiation. For the first time, the relationship between starch achirality (χ21/χ16 and χ22/χ16) and chirality (χ14/χ16) determining susceptibility tensor ratios has been elucidated. The results showed that changes in the structure and orientation of long-chain amylopectin were supported by the decrease in the SHG anisotropy factor and the χ22/χ16 ratio. Furthermore, SHG-CD illustrated the molecular tilt angle by revealing the arrangement of amylopectin molecules pointing either upward or downward owing to molecular polarity.

Keywords: amylopectin; circular dichroism; polarization; second harmonic generation; second-order susceptibility; starch.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Amylopectin*
Second Harmonic Generation Microscopy*
Starch

Substances

Amylopectin
Starch