Photoacoustic spectroscopy of aromatic amino acids in proteins

Effect of mineral elements on the formation of gallbladder stones using spectroscopic techniques

Long-standing gallbladder stones have been recognized as one of the highest risk factors for gallbladder cancer. However, the growth and progression of gallbladder stones are still not well-known, and their uncovering requires accurate information on the formation/nucleation and complex compositional information of gallstones. Multiple and single gallstones are analyzed using laser-induced breakdown spectroscopy (LIBS), photoacoustic spectroscopy (PAS), and Fourier transform infrared spectroscopy (FTIR). Spectral signatures as well as spatial variation in the spectral intensities of different elements are observed in the LIBS spectra of the gallstones. In the multiple-type gallstones, the concentration of inorganic content increases from core to periphery, whereas a single gallstone shows the opposite trend from the point of nucleation/core. It is suggested that the concentration of inorganic elements (Mg, Ca, K, and Na) plays an important role in the nucleation and growth of gallstones; thus, accordingly, multiple- and single-type gallstones are found in the gallbladder. The presence of different electronic bands of molecules, such as CH, C2, CN, and NH, is confirmed by LIBS and FTIR. PAS has identified molecules, such as cholesterol, calcium carbonate, and calcium phosphate, in different gallstone samples. These results show that PAS combined with LIBS is a promising candidate for the compositional analysis of gallstones. Furthermore, principal component analysis (PCA) is used to discriminate different layers present in the gallstones.

Fluorescence and Photoacoustic Spectroscopy-Based Assessment of Mitochondrial Dysfunction in Oral Cancer Together with Machine Learning: A Pilot Study

The current study reports an integrated approach of machine learning and tryptophan fluorescence and photoacoustic spectral properties to assess the mitochondrial status under oral pathological conditions. The mitochondria in the study were isolated from oral cancer tissues and adjacent normal counterparts, and the corresponding fluorescence and photoacoustic spectra of tryptophan were recorded at 281 nm pulsed laser excitations. A set of features were selected from the pre-processed spectra and were used to classify the data using support vector machine (SVM) learning in the MATLAB platform. SVM analysis demonstrated clear differentiation between mitochondria isolated from normal and cancer tissues for fluorescence (sensitivity, 86.6%; specificity, 90%) and photoacoustic (sensitivity, 86.6%; specificity, 96.6%) measurements. Further investigation into the influence of change in protein conformation on the nature of tryptophan spectral properties was evaluated by 8-anilino-1-naphthalene sulfonic acid (ANS) fluorescence assay. The impact of protein structural changes on the mitochondrial functions was also estimated by mitochondrial membrane potential (MMP), reactive oxygen species (ROS), and cytochrome c oxidase (COX) assays, suggesting an altered mitochondrial function. The findings indicate that tryptophan fluorescence and photoacoustic spectral properties together with machine learning algorithms may delineate the mitochondrial functional status in vitro, indicating its translational potential.

Supramolecular nanoassemblies of salmon calcitonin and aspartame for fibrillation inhibition and osteogenesis improvement

Osteoporosis therapy consists of inhibiting the osteoclasts' activity and promoting osteoblasts' osteogenesis. Salmon calcitonin (sCT) could realize both requirements, however, it is limited by the low bioavailability caused by fibrillation. Supramolecular assembly of sCT and biocompatible agents into nanoassemblies provides an opportunity to overcome these shortcomings. Herein, we used a facile method to fabricate salmon calcitonin-aspartame (sCT-APM) nanoassemblies. Supramolecular interactions could not only delay fibrillation time (from 36.9 h to 50.4 h), but also achieve sustained sCT release. Moreover, sCT-APM showed good biocompatibility and higher osteoinductive capacity than free sCT, revealing an osteogenesis improvement effect. Moreover, in vivo studies showed that sCT-APM has enhanced relative bioavailability (2.42-fold of sCT) and increased relative therapeutic efficacy (3.55-fold of sCT) through subcutaneous injection. These findings provide a convenient alternative strategy for osteoporosis therapy via supramolecular assemblies.

Photoacoustic spectroscopy applied to the direct detection of bioactive compounds in Agaricus brasiliensis mycelium

This paper describes the application of the photoacoustic spectroscopic (PAS) for detection of bioactive compounds in Agaricus brasiliensis mycelium. The mycelium was cultivated by solid-state fermentation and by submerged fermentation. Vegetal residues from food industry were used as substrates for fermentation: apple pomace (Malus domestica), wheat (Triticum aestivum), peel and pomace of pineapple (Ananas comosus), malt (Hordeum vulgare) and grape pomace (Vitis vinifera). Dry and ground samples of biomass were directly put into the PA cell. The optical absorption spectra indicated the existence of three main absorption bands: one around 280 nm related to phytosterols (ergosterol), phenolic acids, flavonoids and aromatic amino acids, another at 340 nm, due to phenolic and flavonoid compounds, and the third one at around 550 nm associated with anthocyanins and anthocyanidins. A correlation between the PA signal and the total phenolic content was satisfactory, as well as for the analyzed spectrum region (270 nm up to 1000 nm), using multivariate methods. Our results indicated that PA technique may be considered as an analytical tool to quickly detect bioactive compounds in mushrooms without the need of sample pretreatment.