Raman microspectroscopy was applied to analyze the changes in structural conformation and chemical composition of the mass of human skin pilomatrixoma (PMX). The normal skin dermis, collagen type I, and hydroxyapatite (HA) were used as control. The excised specimens from two patients diagnosed as a typical PMX were detected, in which one specimen was a soft mass, but the other was a hard mass with somewhat calcified deposits via histopathological examination. The Raman spectrum of normal skin dermis was found to be similar to the Raman spectrum of collagen type I, confirming that the collagen type I was a predominant component in normal skin dermis. The differences of Raman peak intensity between normal skin dermis and soft or hard PMX mass were obvious at 1,622-1,558, 1,400-1,230, 1,128, 1,000-850, 749, and 509 cm(-1). In particular, the peak at 1,665 cm(-1) assigned to amide I band shifted to 1,655 cm(-1) and the peak at 1,246 cm(-1) corresponding to amide III band was reduced in its intensity in hard PMX mass. The significant changes in collagen content and its structural conformation, the higher content of tryptophan, and disulfide formation in PMX masses were markedly evidenced. In addition, the shoulder and weak peak at 960 cm(-1) assigned to the stretching vibration of PO(4) (3-) of HA also appeared respectively in the Raman spectra of soft and hard PMX masses, suggesting the occurrence of calcification of HA in the PMX tissue, particularly in the hard PMX mass. The result indicates that the micro-Raman spectroscopy may provide a highly sensitive and specific method for identifying normal skin dermis and how it differs in chemical composition from different PMX tissues.

Fourier transform infrared (FT-IR) and Raman vibrational microspectroscopies used for biomedical diagnosis of human tissues are reviewed from basic principle to biological applications. The advantages and disadvantages of both vibrational microspectroscopies are compared to highlight their efficiency and adaptability for noninvasively investigating the chemical compositions of ultrastructual human tissues at different disease states. Biochemical fingerprints applied to the biological samples by using FT-IR and Raman microspectroscopies are illustrated. The spectral biodiagnoses of several diseased human tissues such as ophthalmic disorders (risk factors-induced cataractous lens capsules and lens, lens and corneal calcifications, opacification and contamination of intraocular lens, vitreous asteroid bodies), alcohol-disordered human gastric mucosa, skin disorders (cancer and calcification), brain tumors (pituitary adenomas and astrocytomas), genetic hair roots disorder (glucose-6-phosphate dehydrogenase deficiency, phenylketonuria and congenital hypothyroidism), benign prostatic hyperplasia, and interstitial cystitis investigated by both vibrational microspectroscopies in our laboratory are introduced.

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.

This work reports the stability and solubility of nesquehonite in several salts (NaCl, NH 4 Cl, MgCl 2 , and KCl) over the temperature range of (15 to 35) °C. The needle-like nesquehonite used in this work was prepared by the reaction of analytical pure MgCl 2 with Na 2 CO 3 . The concentration investigated for all salts was up to 4 mol • dm -3 NaCl, 3.5 mol • dm -3 NH 4 Cl, 4 mol • dm -3 MgCl 2 , and 1.0 mol • dm -3 KCl at ambient temperature. The solubility of nesquehonite in pure water was found to decrease with temperature within the temperature range in which nesquehonite is the stable phase. In NaCl solutions, the solubility of nesquehonite initially increases to a maximum value and then decreases gradually with an increase of the common salt concentration. It was further found that the addition of MgCl 2 , NH 4 Cl, or KCl causes the solubility of nesquehonite to increase due apparently to complexation. XRD and SEM examination of the equilibrated solids showed that nesquehonite is stable in pure water up to 50 °C, but its stability region becomes smaller in concentrated brines.

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A new chemical model of supersaturation (S) was developed and applied to test for the precipitation of hydromagnesite [Mg5(CO3)4(OH)2·4H2O] in the MgCl2−Na2CO3 system in supersaturated solutions over the temperature range of 50−90 °C. Based on the new model with the help of the OLI platform, the contour supersaturation of Mg5(CO3)4(OH)2·4H2O has been exactly constructed by calculating the activity coefficients of species in unstable solutions. Mg5(CO3)4(OH)2·4H2O crystals were identified using X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) images. It was found that the crystal properties, such as morphology, particle size distribution, filtration, and sedimentation characteristics, can be optimized by controlling the supersaturation during precipitation. With the control of supersaturation, well-developed spherical-like Mg5(CO3)4(OH)2·4H2O crystals can grow to an average size of 30−40 μm, indicating a narrow particle size distribution, good filtration characteristics, and a high sedimentation rate. In addition, the Mg5(CO3)4(OH)2·4H2O obtained was calcined to produce high-purity MgO at 800 °C. The size and morphology of MgO were similar to the same characteristics of the corresponding precursors.

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Fourier-transform infrared (FTIR) microspectroscopy combining with attenuated total reflection (ATR) microsampling technique and micro-Raman spectrophotometer were used to detect the deposited materials on the surface of acrylic hydrogel intraocular lens (IOL) with or without ocular implantation. Surface morphology and the interface of this IOL were further examined by a confocal laser scanning microscope. The brand-new IOL exhibited a very smooth, transparent and featureless surface, but the explanted IOL had an irregular cerebriform-like opaque appearance. Both FTIR/ATR and Raman microspectroscopic analyses showed the deposits on the surface of acrylic hydrogel IOL after ocular implantation to consist of octacalcium phosphate (OCP) and Type B carbonated apatites, leading to the opalescence of acrylic hydrogel IOL. Both vibrational microspectroscopic examinations also confirmed the mineralization still in progress on the surface of acrylic hydrogel IOL after ocular implantation for 2 years.