Laser imaging polarimetry of nacre. Issue 10 (18th July 2018)

• Record Type: Journal Article
• Authors: Jones, Joshua A.; Metzler, Rebecca A.; D'Addario, Anthony J.; Burgess, Carrie; Regan, Brian; Spano, Samantha; Cvarch, Ben A.; Galvez, Enrique J.
• Is Part Of: Journal of biophotonics. Volume 11:Issue 10(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-07-18
• Subjects: imaging -- nacre -- polarimetry -- shell; Photonics -- Periodicals; Optical materials -- Periodicals; Optics -- Periodicals; Medical instruments and apparatus -- Periodicals; 621.3605
• DOI: 10.1002/jbio.201800026
• Languages: English
• ISSNs: 1864-063X

Abstract

Abstract : Nacre is a complex biomaterial made of aragonite‐tablet bricks and organic mortar that is considerably resilient against breakage. Nacre has been studied with a wide range of laboratory techniques, leading to understanding key fundamentals and informing the creation of bio‐inspired materials. In this article, we present an optical polarimetric technique to investigate nacre, taking advantage of the translucence and birefringence of its microcomponents. We focus our study on 3 classes of mollusks that have nacreous shells: bivalve ( Pinctada fucata ), gastropod ( Haliotis asinina and Haliotis rufescens ) and cephalopod ( Nautilus pompilius ). We sent polarized light from a laser through thin samples of nacre and did imaging polarimetry of the transmitted light. We observed clear distinctions between the structures of bivalve and gastropod, due to the spatial variation of their birefringence. The patterns for cephalopod were more similar to bivalve than gastropod. Bleaching of the samples disrupted the transmitted light. Subsequent refilling of the bivalve and gastropod nacre samples with oil produced optical patterns similar to those of unbleached samples. In cephalopod samples, we found that bleaching produced irreversible changes in the optical pattern. Abstract : Nacre is a brick‐and‐mortar type of structure made of micron‐sized aragonite tablets (bricks) embedded in organic matter (mortar). The refractive properties of aragonite modify the polarized light going through it. Sending polarized light through this self‐assembled natural structure reveals uniformity in the orientations of aragonite tablets over thousands of tablets for 2 classes of shell: bivalve and cephalopod; and contrasting evidence of regional variations for a third class: gastropod.