Characterization of Developing Cotton Fibers by Confocal Raman Microscopy

Luis Cabrales,Noureddine Abidi,Felicia Manciu

doi:10.3390/fib2040285

Abstract

Cellulose deposition in developing cotton fibers has been studied previously with analytical techniques, such as Fourier transform infrared spectroscopy (FTIR), High-performance liquid chromatography (HPLC) and Thermogravimetric analysis (TGA). Recent technological developments in instrumentation have made Raman microscopy emerge as an extraordinary analytical tool in biological and plant research. The advantage of using confocal Raman microscopy (CRM) resides in the lateral spatial resolution and in the fact that Raman spectroscopy provides not only chemical composition information, but also structural information. Cross-sections of cotton fibers harvested at different developmental stages were studied with CRM. The Raman bands assigned to cellulose were analyzed. The results of this study indicate that CRM can be used as a tool to study cellulose deposition in cotton fibers and could provide useful information on cellulose deposition during cotton fiber development.

Highlights

Raman scattering involves the excitation of a molecule by inelastic scattering with a photon, and it depends on changes in the polarizability due to molecular vibrations
Maturity is reached at 56 dpa, and the secondary cell wall (SCW) is clearly the main constituent of the cotton fiber [8]
The crystallinity of developing cotton fibers was obtained by XRD, and the results are in agreement with previously-reported results

Summary

Introduction

Raman scattering involves the excitation of a molecule by inelastic scattering with a photon, and it depends on changes in the polarizability due to molecular vibrations. Because of recent technological developments in instrumentation, Raman microscopy has emerged as a powerful analytical tool in biological and plant research [1]. Confocal Raman microscopy (CRM) presents some advantages compared to other chemical imaging techniques. Due to the fact that Fourier transform infrared spectroscopy (FTIR) uses longer wavelengths, the diffraction-limited resolution is in the micron scale, around 5 microns with attenuated total reflectance (ATR) imaging [2]. Raman spectroscopy is not sensitive to water content in samples, as is the case with IR spectroscopy [1]. UV microscopy is close in resolution (~250 nm) to CRM, but it lacks the precise functional group identification [3]. The resolution of CRM is in the submicron scale, close to 200 nm, using a laser in the visible region [4]

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