Laser-induced breakdown spectroscopy-Raman: An effective complementary approach to analyze renal-calculi

Physicochemical understanding of biomineralization by molecular vibrational spectroscopy: From mechanism to nature

The process and mechanism of biomineralization and relevant physicochemical properties of mineral crystals are remarkably sophisticated multidisciplinary fields that include biology, chemistry, physics, and materials science. The components of the organic matter, structural construction of minerals, and related mechanical interaction, etc., could help to reveal the unique nature of the special mineralization process. Herein, the paper provides an overview of the biomineralization process from the perspective of molecular vibrational spectroscopy, including the physicochemical properties of biomineralized tissues, from physiological to applied mineralization. These physicochemical characteristics closely to the hierarchical mineralization process include biological crystal defects, chemical bonding, atomic doping, structural changes, and content changes in organic matter, along with the interface between biocrystals and organic matter as well as the specific mechanical effects for hardness and toughness. Based on those observations, the special physiological properties of mineralization for enamel and bone, as well as the possible mechanism of pathological mineralization and calcification such as atherosclerosis, tumor micro mineralization, and urolithiasis are also reviewed and discussed. Indeed, the clearly defined physicochemical properties of mineral crystals could pave the way for studies on the mechanisms and applications.

Chemical Studies of Multicomponent Kidney Stones Using the Modern Advanced Research Methods

Defining the kidney stone composition is important for determining a treatment plan, understanding etiology and preventing recurrence of nephrolithiasis, which is considered as a common, civilization disease and a serious worldwide medical problem. The aim of this study was to investigate the morphology and chemical composition of multicomponent kidney stones. The identification methods such as infrared spectroscopy (FTIR), X-ray diffraction (XRD), and electron microscopy with the EDX detector were presented. The studies by the X-ray photoelectron spectroscopy (XPS) were also carried out for better understanding of their chemical structure. The chemical mapping by the FTIR microscopy was performed to show the distribution of individual chemical compounds that constitute the building blocks of kidney stones. The use of modern research methods with a particular emphasis on the spectroscopic methods allowed for a thorough examination of the subject of nephrolithiasis.

Study on the pathogenesis and prevention strategies of kidney stones based on GC-MS combined with metabolic pathway analysis

RATIONALE

Most kidney stone composition analyses include organic compounds, and only few organic volatile compounds have been reported.

METHODS

In the present study, a novel approach for studying the pathogenesis and prevention of kidney stones was established. First, common organic volatile compounds were detected using gas chromatography-mass spectrometry (GC-MS) in 137 kidney stone samples. The Kyoto Encyclopedia of Genes and Genomes database and MetaboAnalyst 5.0 software were then used to analyze the metabolic pathways associated with the development of kidney stones.

RESULTS

The metabolic pathway analysis of the common component cholesterol revealed that two metabolic pathways, the steroid biosynthesis pathway and the primary bile acid biosynthesis pathway, were closely associated with the formation of kidney stones. The pretreatment process for stone analysis, including the solvent type, solvent volume, and extraction time, was optimized to improve the detection efficiency. The calibration curve was y = 756 299x - 8 000 000, with a correlation coefficient (r) of 0.9992, which was obtained over the concentration range of 10-500 μg ml^-1 of cholesterol. The recovery values of cholesterol ranged from 93.34% to 94.67%, 96.98% to 99.23%, and 87.27% to 93.00% when spiked with 0.75, 1.00, and 1.25 μg, respectively, with a relative standard deviation of no less than 3.18%. Finally, the content of common compounds was determined in 37 renal stone samples using the modified GC-MS method.

CONCLUSIONS

The common organic volatile compound in the kidney stone samples detected using GC-MS was cholesterol, and the steroid biosynthesis and primary bile acid biosynthesis pathways were determined to be closely associated with the formation of kidney stones. The GC-MS method for detecting cholesterol in kidney stones was optimized for efficiency and accuracy.

Evaluation of electrolyte element composition in human tissue by laser-induced breakdown spectroscopy (LIBS)

Laser-induced breakdown spectroscopy (LIBS) enables the direct measurement of cell electrolyte concentrations. The utility of LIBS spectra in biomarker studies is limited because these studies rarely consider basic physical principles. The aim of this study was to test the suitability of LIBS spectra as an analytical method for biomarker assays and to evaluate the composition of electrolyte elements in human biomaterial. LIBS as an analytical method was evaluated by establishing KCl calibration curves to demonstrate linearity, by the correct identification of emission lines with corresponding reference spectra, and by the feasibility to use LIBS in human biomaterial, analyzing striated muscle tissues from the oral regions of two patients. Lorentzian peak fit and peak area calculations resulted in better linearity and reduced shot-to-shot variance. Correct quantitative measurement allowed for differentiation of human biomaterial between patients, and determination of the concentration ratios of main electrolytes within human tissue. The clinical significance of LIBS spectra should be evaluated using peak area rather than peak intensity. LIBS might be a promising tool for analyzing a small group of living cells. Due to linearity, specificity and robustness of the proposed analytical method, LIBS could be a component of future biomarker studies.

Preliminary assessment of a portable Raman spectroscopy system for post-operative urinary stone analysis

PURPOSE

We aimed to evaluate the reliability of a portable device that applies Raman spectroscopy at an excitation wavelength of 1064 nm for the post-operative analysis of urinary stone composition.

MATERIALS AND METHODS

Urinary stone samples were obtained post-operatively from 300 patients. All samples were analyzed by the portable Raman spectroscopy system at an excitation wavelength of 1064 nm as well as by infrared spectroscopy (IR), and the results were compared.

RESULTS

Both Raman spectroscopy and IR could detect multiple stone components, including calcium oxalate monohydrate, calcium oxalate dihydrate, calcium phosphate, uric acid, cystine, and magnesium ammonium phosphate hexahydrate. The results from 1064-nm Raman analysis matched those from IR analysis for 96.0% (288/300) of cases. Although IR detected multiple components within samples more often than Raman analysis (239 vs 131), the Raman analysis required less time to complete than IR data acquisition (5 min vs 30 min).

CONCLUSIONS

These preliminary results indicate that 1064-nm Raman spectroscopy can be applied in a portable and automated analytical system for rapid detection of urinary stone composition in the post-operative clinical setting.

TRIAL REGISTRATION

Chinese Clinical Trail Register ID: ChiCTR2000039810 (approved WHO primary register) http://www.chictr.org.cn/showproj.aspx?proj=63662 .

Using LIBS as a diagnostic tool in pediatrics beta-thalassemia

Beta-thalassemia major is a common inherited single-gene disorder. Thalassemic patients are at risk of changes in some important trace elements. To detect alteration of iron, copper, zinc, and calcium serum levels in beta-thalassemia major patients, laser-induced breakdown spectroscopy (LIBS) was used. This study was conducted on 40 beta-thalassemia major and 40 healthy young patients (age: 12-18 years old; male:female = 1:1). Venous blood samples were collected from both groups and analyzed for the serum levels of iron, calcium, zinc, and copper by exposing the samples to LIBS. The intensities of the tested elements were detected using the Kestrel Spec computer software and analyzed with an SPSS 25 program. Thalassemic patients had significantly higher serum iron (p = < 0.001) and copper (p = < 0.005) while they had significantly lower serum zinc (p = < 0.005) and calcium (p= > 0.005) when compared with control. Also, thalassemic patients had significantly lower body weight and height as they were less than the 3rd percentile by 82.5% and p < 0.001. LIBS is a safe and efficient tool to detect alteration of some serum trace elements in beta-thalassemia patients.

Analysis and classification of kidney stones based on Raman spectroscopy

The number of patients with kidney stones worldwide is increasing, and it is particularly important to facilitate accurate diagnosis methods. Accurate analysis of the type of kidney stones plays a crucial role in the patient's follow-up treatment. This study used microscopic Raman spectroscopy to analyze and classify the different mineral components present in kidney stones. There were several Raman changes observed for the different types of kidney stones and the four types were oxalates, phosphates, purines and L-cystine kidney stones. We then combined machine learning techniques with Raman spectroscopy. KNN and SVM combinations with PCA (PCA-KNN, PCA-SVM) methods were implemented to classify the same spectral data set. The results show the diagnostic accuracies are 96.3% for the PCA-KNN and PCA-SVM methods with high sensitivity (0.963, 0.963) and specificity (0.995,0.985). The experimental Raman spectra results of kidney stones show the proposed method has high classification accuracy. This approach can provide support for physicians making treatment recommendations to patients with kidney stones.

Raman chemical imaging, a new tool in kidney stone structure analysis: Case-study and comparison to Fourier Transform Infrared spectroscopy

BACKGROUND AND OBJECTIVES

The kidney stone's structure might provide clinical information in addition to the stone composition. The Raman chemical imaging is a technology used for the production of two-dimension maps of the constituents' distribution in samples. We aimed at determining the use of Raman chemical imaging in urinary stone analysis.

MATERIAL AND METHODS

Fourteen calculi were analyzed by Raman chemical imaging using a confocal Raman microspectrophotometer. They were selected according to their heterogeneous composition and morphology. Raman chemical imaging was performed on the whole section of stones. Once acquired, the data were baseline corrected and analyzed by MCR-ALS. Results were then compared to the spectra obtained by Fourier Transform Infrared spectroscopy.

RESULTS

Raman chemical imaging succeeded in identifying almost all the chemical components of each sample, including monohydrate and dihydrate calcium oxalate, anhydrous and dihydrate uric acid, apatite, struvite, brushite, and rare chemicals like whitlockite, ammonium urate and drugs. However, proteins couldn't be detected because of the huge autofluorescence background and the small concentration of these poor Raman scatterers. Carbapatite and calcium oxalate were correctly detected even when they represented less than 5 percent of the whole stones. Moreover, Raman chemical imaging provided the distribution of components within the stones: nuclei were accurately identified, as well as thin layers of other components. Conversion of dihydrate to monohydrate calcium oxalate was correctly observed in the centre of one sample. The calcium oxalate monohydrate had different Raman spectra according to its localization.

CONCLUSION

Raman chemical imaging showed a good accuracy in comparison with infrared spectroscopy in identifying components of kidney stones. This analysis was also useful in determining the organization of components within stones, which help locating constituents in low quantity, such as nuclei. However, this analysis is time-consuming, making it more suitable for research studies rather than routine analysis.