FT-IR imaging for quantitative determination of liver fat content in non-alcoholic fatty liver

In this work we apply FT-IR imaging of large areas of liver tissue cross-section samples (∼5 cm × 5 cm) for quantitative assessment of steatosis in murine model of Non-Alcoholic Fatty Liver (NAFLD). We quantified the area of liver tissue occupied by lipid droplets (LDs) by FT-IR imaging and Oil Red O (ORO) staining for comparison. Two alternative FT-IR based approaches are presented. The first, straightforward method, was based on average spectra from tissues and provided values of the fat content by using a PLS regression model and the reference method. The second one – the chemometric-based method – enabled us to determine the values of the fat content, independently of the reference method by means of k-means cluster (KMC) analysis. In summary, FT-IR images of large size liver sections may prove to be useful for quantifying liver steatosis without the need of tissue staining

Determining the Age of Spoiled Milk from Dried Films Using Attenuated Reflection Fourier Transform Infrared (ATR FT-IR) Spectroscopy

Milk spoilage is an inevitable occurrence, which generates waste and can result in food poisoning. When milk spoils, the off-flavor and curdling are due to excessive proliferation of various bacteria which causes pH changes. Time, temperature, environment,and previous handling practice all affects the spoilage rate. There is a need for a fast reliable and accurate method that can identify in situearly spoilage of milk. Here we show the ability of attenuated total reflectionFourier transformed infrared spectroscopy(ATR FT-IR) in conjunction with multivariate data analysis to predict the age of milk. We found that dried films vastly increased the absorbance of important biomolecules within milk such as lipids, proteins,and sugars, compared to an unchanged milk sample. This allowed us to note the minor discrepancies that happened in spoilage. Spoilt milk was characterizedby bands associated with increased lipids, proteins, lactic acid; and a decrease in carbohydrates. A semiquantitative prediction model for milk spoilage at room temperature demonstrated ATR FT-IRspectroscopy can predict milk age with a root mean square error of prediction of approximately 14 hours.The model showed poor performance in the first 40 hours but the predictions improved significantly after this time. The experimental procedure proposed for detecting biomolecules within milk has the potential to improve common practice. Furthermore, the model would be a starting point for a newer and improved methods to predict the spoilage date of milk, with potential commercial uses to reduce food waste and costs to the milk industry

Infrared based saliva screening test for COVID-19

Abstract: Severe acute respiratory syndrome coronavirus 2 has resulted in an unprecedented need for diagnostic testing that is critical in controlling the spread of COVID-19. We propose a portable infrared spectrometer with purpose-built transflection accessory for rapid point-of-care detection of COVID-19 markers in saliva. Initially, purified virion particles were characterized with Raman spectroscopy, synchrotron infrared (IR) and AFM-IR. A data set comprising 171 transflection infrared spectra from 29 patients testing positive for SARS-CoV-2 by RT-qPCR and 28 testing negative, was modeled using Monte Carlo Double Cross Validation with 50 randomized test and model sets. The testing sensitivity was 93 % (27/29) with a specificity of 82 % (23/28) that included positive samples on the limit of detection for RT-qPCR. Here, we demonstrate a proof-of-concept high throughput infrared COVID-19 test that is rapid, inexpensive, portable and utilizes sample self-collection thus minimizing the risk to healthcare workers and ideally suited to mass screening

Efficient long-range conduction in cable bacteria through nickel protein wires

Filamentous cable bacteria display long-range electron transport, generating electrical currents over centimeter distances through a highly ordered network of fibers embedded in their cell envelope. The conductivity of these periplasmic wires is exceptionally high for a biological material, but their chemical structure and underlying electron transport mechanism remain unresolved. Here, we combine high-resolution microscopy, spectroscopy, and chemical imaging on individual cable bacterium filaments to demonstrate that the periplasmic wires consist of a conductive protein core surrounded by an insulating protein shell layer. The core proteins contain a sulfur-ligated nickel cofactor, and conductivity decreases when nickel is oxidized or selectively removed. The involvement of nickel as the active metal in biological conduction is remarkable, and suggests a hitherto unknown form of electron transport that enables efficient conduction in centimeter-long protein structures

Imaging of single cells using FT – IR spectroscopy

Celem pracy było zastosowanie absorpcyjnej spektroskopii w podczerwieni (FT-IR) do obrazowania komórek śródbłonka, wykorzystując technikę transmisyjną oraz całkowitego osłabionego odbicia (ATR). Uzyskane wyniki obrazowania poddano następnie szczegółowej analizie, stosując różne podejścia, m.in. analizę pojedynczych pasm oraz metody chemometryczne. Dla obu trybów ustalono metodologię pomiarową. W przypadku techniki ATR zbadano zagadnienie kontaktu powierzchni kryształu z próbką, natomiast dla trybu transmisyjnego wybrano optymalną rozdzielczość spektralną oraz liczbę skanów. Uzyskane obrazy poddano analizie pod kątem identyfikacji głównych komponentów komórki oraz ich dystrybucji. Następnie porównano wyniki otrzymane w obu trybach, celem wyboru metody pomiarowej o większym potencjale w kontekście obrazowania pojedynczych komórek. Przedstawiono również aplikację dwóch technik analizy skupień: hierarchicznej (HCA) oraz k – średnich (KMC), do badania zmierzonych obrazów. Do analizy skupień obrazów otrzymanych techniką ATR dobrano optymalne parametry oraz zbadano wpływ takich czynników, jak: normalizacja danych oraz zakres spektralny, w celu wyboru najlepszej metody skupiania. Dla wyników uzyskanych w trybie transmisyjnym również ustalono parametry optymalne dla obu metod skupiania, a następnie poddano ocenie przydatność tego podejścia do analiz uzyskanych obrazów.The paper presents application of infrared absorption spectroscopy for imaging endothelial cells, using the technique of transmission and ATR. The results were analyzed using different approaches, including analysis of individual spectra and chemometric tools. For both modes of measurement methodology was established. In the case of the ATR technique the issue of contact between the sample and crystal surface was examined, while for the transmission mode optimal spectral resolution and number of scans were selected. The resulting images were analyzed in terms of identifying the major components of cells and their distribution. The results obtained in both modes were compared in order to choose the method of measurement with a greater potential in the context of single-cell imaging. The paper also presents an application of two cluster analysis techniques: hierarchical (HCA) and k - means (KMC), to study measured images. In the case of ATR for both clustering methods optimal parameters were selected and the influence of other factors, such as data normalization and the spectral range, was examined in order to select the best method of clustering. For the results in the transmission mode, the optimal parameters for both methods of clustering were established and then assesses the usefulness of this approach to analysis of obtained images