Calcification of senile cataractous lens determined by Fourier transform infrared (FTIR) and Raman microspectroscopies

Abstract

SummaryA calcified plaque on the surface of a senile cataractous lens (CL) isolated from a 79-year-old male patient was identified and its chemical composition quantified using Fourier transform infrared (FTIR) and confocal Raman microspectroscopies. The noncalcified area of the same CL and hydroxyapatite (HA) were selected as a control. Several unique absorption bands, at 960, 1034 and 1090 cm − 1 assigned to the ν 1 and ν 3 stretching modes of phosphate and at 875 cm − 1 attributed to carbonate, were clearly displayed in the infrared (IR) spectra of calcified plaque and HA. A peak at 961 cm − 1 due to the ν 1 stretching mode of phosphate was also evidenced in the Raman spectra of calcified plaque and HA. The calcified plaque formed within the lens protein was found to mainly consist of a mature HA, in which type-A carbonate apatites (11.4%), type-B carbonate apatites (55.6%) and liable surface carbonate ions (33.0%) were presented. A higher content of the liable carbonate implies that the calcification or mineralization in this calcified lens was incomplete and still in progress. Moreover, calcification seems not to influence the secondary structure of lens protein because both IR and Raman spectra for the lens protein in the noncalcified area and calcified plaque were similar. The result suggests that both microscopic FTIR and Raman spectroscopies were easy to perform and capable of determination of the chemical composition of a calcified CL.

Infrared microspectroscopic imaging as a probing tool to fast distinguish chemical compositions in calcified deposits of prostatic calculi and calcific tendonitis

“…A trace amount of each fine calcified sample was sealed within two KBr pellets by a hydraulic press under 400 kg/cm 2 compression pressure for 15 s to form a KBr disc [7,8,11,23,27,28]. The fine powders distributed within KBr disc were observed and photographed by infrared microscope (IRT-5000-16/FTIR-6200, Jasco Co., Tokyo, Japan) with a video camera.…”

“…Each KBr disc prepared from different samples was examined to determine the chemical component using an FT-IR microspectroscopy (IRT-5000-16/FTIR-6200, Jasco Co.) equipped with an MCT detector via a transmission technique [7,8,11,23,27,28]. The traditional single-point FT-IR spectral analysis was randomly detected via a manual determination.…”

“…Recently, the application of Fourier transform infrared (FT-IR) microspectroscopy to clinical studies has been focused on the diagnosis of diseases and laboratory analyses of pathological samples, particularly for characterization of the biological mineralization [1,4,16]. In the traditional FT-IR analysis without microscopy, this technique allows identifying any organic or inorganic molecules in the calcified samples by grinding the sample with KBr powder or sealing the sample within two KBr pellets for spectral determination after compression [6,8,11]. In our previous studies, several human calcified tissues, such as calcinosis cutis, skin pilomatrixoma, cornea, senile cataractous lens, vitreous asteroid bodies, sclera and superior vesical artery had been investigated using this powerful and convenient vibrational microspectroscopic technique [7][8][9][10][11]23,27,28].…”

“…In the traditional FT-IR analysis without microscopy, this technique allows identifying any organic or inorganic molecules in the calcified samples by grinding the sample with KBr powder or sealing the sample within two KBr pellets for spectral determination after compression [6,8,11]. In our previous studies, several human calcified tissues, such as calcinosis cutis, skin pilomatrixoma, cornea, senile cataractous lens, vitreous asteroid bodies, sclera and superior vesical artery had been investigated using this powerful and convenient vibrational microspectroscopic technique [7][8][9][10][11]23,27,28]. However, the main drawback of this technique is that the manual singlepoint random determination at microscopic level cannot really reflect the spatial distribution of all the components in the mixture, leading to possibly inaccurate diagnose of the complicated components in the calcified mixture.…”

Micro-FTIR imaging spectroscopy of calcified atheromatous carotid plaques. Part IV

“…In vivo near-IR spectroscopy allows to analyse proteins and lipids involved in carotid atherosclerosis lesions and to provide a ''chemogram" of the wall of the artery indicative of an index of vulnerability [11]. In ex vivo studies, middle infrared and Raman spectroscopy can provide a more exhaustive biochemical and diagnostic knowledge of many pathologies resulting important to understand the mechanism of their evolution and to highlight subtle changes at an early stage [11][12][13][14].…”