Non-biological Samples Research Articles

A shifted ratio spectrum strategy for effective subtraction of fluorescence interference in Raman spectra.

Raman spectroscopy is an important technique for analyzing the chemical composition of samples in many fields. A severe challenge often encountered in Raman measurements is the presence of a concurrent fluorescence background, especially in biological samples. In order to obtain accurate Raman spectra, the fluorescence background must be subtracted from the original Raman spectra. We proposed a shifted ratio spectrum method to subtract the strong fluorescence background from the original Raman spectrum. First, the original Raman spectrum is divided into multiple regions according to the spectral shape of the shifted ratio spectra, and then, Gaussian fitting is performed in each region. The fitting results are stitched together in order to obtain the complete fluorescence background. Finally, this fluorescence background is subtracted from the original spectrum to obtain a pure Raman spectrum. This method can accurately subtract the fluorescence background of Rhodamine 6G (R6G)/ethanol solution and serum. This highlights the great potential of this method for applications in both biological and non-biological samples.

Characterization of Microscopic Structures in Living Tumor by In Vivo Measurement of Magnetic Relaxation Time Distribution of Intratumor Magnetic Nanoparticles.

Tumor microscopic structure is crucial for determining properties such as cancer type, disease state (key for early diagnosis), and novel therapeutic strategies. Magnetic particle imaging is an early cancer diagnostic tool using magnetic nanoparticles as a tracer, which actualizes cancer theranostics in combination with hyperthermia treatment using the abilities of magnetic nanoparticles as a heat source. This study focuses on the microscopic structures associated with cancer cell distribution, the stromal compartment, and vascularization in different kinds of living tumors by analyzing the intratumor magnetic relaxation response of magnetic nanoparticles injected into the tumors. Furthermore, this study describes a sequential system for the measurement of magnetic relaxation time and analysis of the intratumor structure using nonbiological samples such as viscous fluids and solidified magnetic nanoparticles. Particularly, the fine discriminability achieved by reconstructing a distribution map representing the relationship between magnetic relaxation time and viscosity of medium is demonstrated, based on experimental data with a limited condition number. Observing tumor microscopic structure through the dynamic magnetization response of intratumor magnetic nanoparticles is a low-invasive tool for analyzing tumor tissue without dissection. It holds promise for the advancement of biomedical applications, such as early cancer theranostics, using magnetic nanoparticles.

Biological Potential of Kakkalide in Medicine for the Treatment of Human Disorders: An Overview of Pharmacological Aspects.

Pueraria lobata is an important herbal medicine of Fabaceae family that has been clinically used in Traditional Chinese Medicine to counteract human disorders and associated secondary complications. Kakkalide also called irisolidone 7-xylosylglucoside is an isoflavonoid of Puerariae flos, Pueraria lobata and Flos Puerariae. Moreover, Kakkalide has a wide range of bioactivities in medicine. Biological potential of kakkalide was investigated in the present work through scientific data analysis of different scientific research work on kakkalide in order to know its therapeutic potential in medicine. Scientific data on Pueraria lobata were collected and analyzed in the present work. All the scientific data were collected from Google, Google Scholar, Scopus, and Science Direct in the present work. Scientific data analysis of kakkalide revealed its biological importance and therapeutic potential in medicine. The present investigation signified kakkalide's effectiveness in inflammatory diseases, prostaglandin E2 production, liver complication, gastric injury, alcoholism, insulinresistant endothelial dysfunction, aldose reductase enzyme, hyperlipidemia, estrogenic activity, and stroke. In addition, the bioavailability of kakkalide was also discussed in the present paper. Present work also revealed the significance of analytical techniques for the separation, isolation and identification of kakkalide in different biological and non-biological samples. Present paper signified the health-beneficial aspects of kakkalide in medicine.

Hydrophilic Interaction Liquid Chromatography for the Analysis of Pharmaceutical Formulations

Abstract: For a long time, Reversed-Phase Liquid Chromatography (RPLC) was the most dominant technique for the analysis of pharmaceutical compounds, but with poor efficiency in the separation of small polar molecules. From the efforts to solve the problem of insufficient retention of these molecules, during the last decades, a mode of liquid chromatography named Hydrophilic Interaction Liquid Chromatography (HILIC) has experienced vast expansion. It is based on the use of a highly hydrophilic stationary phase along with an aqueous mobile phase with high organic modifier content. In this review, the characteristics of stationary and mobile phases used in HILIC are described, and corresponding separation mechanisms are discussed. An overview of recently published papers dealing with the application of HILIC in analyzing pharmaceuticals in biological and non-biological samples is provided. Besides, the application of HILIC systems in the determination of the physicochemical properties of compounds is described.

Untrained neural network enabling fast and universal structured-illumination microscopy.

Structured-illumination microscopy (SIM) offers a twofold resolution enhancement beyond the optical diffraction limit. At present, SIM requires several raw structured-illumination (SI) frames to reconstruct a super-resolution (SR) image, especially the time-consuming reconstruction of speckle SIM, which requires hundreds of SI frames. Considering this, we herein propose an untrained structured-illumination reconstruction neural network (USRNN) with known illumination patterns to reduce the amount of raw data that is required for speckle SIM reconstruction by 20 times and thus improve its temporal resolution. Benefiting from the unsupervised optimizing strategy and CNNs' structure priors, the high-frequency information is obtained from the network without the requirement of datasets; as a result, a high-fidelity SR image with approximately twofold resolution enhancement can be reconstructed using five frames or less. Experiments on reconstructing non-biological and biological samples demonstrate the high-speed and high-universality capabilities of our method.

Advancements in Preprocessing and Analysis of Nitrite and Nitrate since 2010 in Biological Samples: A Review.

As a substance present in organisms, nitrite is a metabolite of nitric oxide and can also be ingested. Nitrate is the metabolite of nitrite. Therefore, it is necessary to measure it quickly, easily and accurately to evaluate the health status of humans. Although there have been several reviews on analytical methods for non-biological samples, there have been no reviews focused on both sample preparation and analytical methods for biological samples. First, rapid and accurate nitrite measurement has significant effects on human health. Second, the detection of nitrite in biological samples is problematic due to its very low concentration and matrix interferences. Therefore, the pretreatment plus measuring methods for nitrite and nitrate obtained from biological samples since 2010 are summarized in the present review, and their prospects for the future are proposed. The treatment methods include liquid-liquid microextraction, various derivatization reactions, liquid-liquid extraction, protein precipitation, solid phase extraction, and cloud point extraction. Analytical methods include spectroscopic methods, paper-based analytical devices, ion chromatography, liquid chromatography, gas chromatography-mass spectrometry, electrochemical methods, liquid chromatography-mass spectrometry and capillary electrophoresis. Derivatization reagents with rapid quantitative reactions and advanced extraction methods with high enrichment efficiency are also included. Nitrate and nitrate should be determined at the same time by the same analytical method. In addition, much exploration has been performed on formulating fast testing through microfluidic technology. In this review, the newest developments in nitrite and nitrate processing are a focus in addition to novel techniques employed in such analyses.

Estimation-free spatial-domain image reconstruction of structured illumination microscopy

Structured illumination microscopy (SIM) achieves super-resolution (SR) by modulating the high-frequency information of the sample into the passband of the optical system and subsequent image reconstruction. The traditional Wiener-filtering-based reconstruction algorithm operates in the Fourier domain, it requires prior knowledge of the sinusoidal illumination patterns which makes the time-consuming procedure of parameter estimation to raw datasets necessary, besides, the parameter estimation is sensitive to noise or aberration-induced pattern distortion which leads to reconstruction artifacts. Here, we propose a spatial-domain image reconstruction method that does not require parameter estimation but calculates patterns from raw datasets, and a reconstructed image can be obtained just by calculating the spatial covariance of differential calculated patterns and differential filtered datasets (the notch filtering operation is performed to the raw datasets for attenuating and compensating the optical transfer function (OTF)). Experiments on reconstructing raw datasets including nonbiological, biological, and simulated samples demonstrate that our method has SR capability, high reconstruction speed, and high robustness to aberration and noise.

Investigation of Equivalence Between Non-Resonant Raman Excitation Spectroscopy and Conventional Raman Spectroscopy

As spontaneous Raman spectroscopy is demonstrated to be viable for many applications, it is still held back by its inherently low signal and typically extended acquisition time. While several techniques can overcome this by enhancing the scattered signal to quicken acquisition, a parallel field that quickens spectral acquisition using instrumentation has received less focus. In principle, Raman spectra could be obtained by tuning the excitation wavelength and measuring the Raman signal at a fixed wavelength using a single-pixel detector. Before exploring the potential of quicker acquisition, it is important to first study the equivalence of Raman Excitation Spectroscopy and conventional Raman Spectroscopy experimentally. We demonstrate the equivalence between the two techniques for biological and non-biological samples by measuring Raman Excitation Maps. Additionally, we explore the interpolation of low-resolution excitation spectra using excess information in the maps for higher resolution excitation spectra. This work, together with current progression in fast tunable lasers and highly sensitive single-pixel detectors, provides a promising prospect for dedicated Raman Excitation Spectroscopy instruments to be developed.

Label-free super-resolution microscopy based on non-diffraction superoscillation beam (NDSB) illumination

Due to the diffraction properties of light waves, optical microscopy suffers from a fundamentally limited resolution of ∼λ/2, where λ relates to the illumination wavelength. Though near-field methods capturing the evanescent waves can reach a resolution of several nanometers, the extremely short working distance has restrained their applications. Typical far-field super-resolution microscopies using fluorescence to monitor the labelled samples also have their limitations in applications because of their phototoxicity and complex preprocessing. We hereby proposed a label-free super-resolution microscopy based on non-diffraction superoscillation beam (NDSB) illumination. We developed a transmission-mode confocal optical microscopy and experimentally demonstrated an imaging resolution of 0.285 λ at the illumination wavelength of 632.8 nm. As NDSB owns the capabilities of self-healing and deep penetration in dense media, we could clearly visualize the fine complex structures while NDSB illuminated from the backside of a 175-µm-thick glass substrate. As a result of NDSB's excellent penetration and superoscillatory transverse size, the 3D super-resolution capability of the proposed microscopy was experimentally verified. Owing to the advantages of label-free imaging, far field, super resolution, self-healing behaviour and deep penetration, we believe the proposed NDSB microscopy bears the potential to become a promising tool for 3D super-resolution visualization in both biological and nonbiological samples.

DNA Origami Fiducial for Accurate 3D Atomic Force Microscopy Imaging.

Atomic force microscopy (AFM) is a powerful technique for imaging molecules, macromolecular complexes, and nanoparticles with nanometer resolution. However, AFM images are distorted by the shape of the tip used. These distortions can be corrected if the tip shape can be determined by scanning a sample with features sharper than the tip and higher than the object of interest. Here we present a 3D DNA origami structure as fiducial for tip reconstruction and image correction. Our fiducial is stable under a broad range of conditions and has sharp steps at different heights that enable reliable tip reconstruction from as few as ten fiducials. The DNA origami is readily codeposited with biological and nonbiological samples, achieves higher precision for the tip apex than polycrystalline samples, and dramatically improves the accuracy of the lateral dimensions determined from the images. Our fiducial thus enables accurate and precise AFM imaging for a broad range of applications.

Quantifying the Extent of Calcification of a Coccolithophore Using a Coulter Counter.

Although, in principle, the Coulter Counter technique yields an absolute measure of particle volume, in practice, calibration is near-universally employed. For regularly shaped and non-biological samples, the use of latex beads for calibration can provide sufficient accuracy. However, this is not the case with particles encased in biogenically formed calcite. To date, there has been no effective route by which a Coulter Counter can be calibrated to enable the calcification of coccolithophores—single cells encrusted with biogenic calcite—to be quantified. Consequently, herein, we seek to answer the following question: to what extent can a Coulter Counter be used to provide accurate information regarding the calcite content of a single-species coccolithophore population? Through the development of a new calibration methodology, based on the measurement and dynamic tracking of the acid-driven calcite dissolution reaction, a route by which the cellular calcite content can be determined is presented. This new method allows, for the first time, a Coulter Counter to be used to yield an absolute measurement of the amount of calcite per cell.

Multi-modal microscopy imaging with the OpenFlexure Delta Stage.

Microscopes are vital pieces of equipment in much of biological research and medical diagnostics. However, access to a microscope can represent a bottleneck in research, especially in lower-income countries. 'Smart' computer controlled motorized microscopes, which can perform automated routines or acquire images in a range of modalities are even more expensive and inaccessible. Developing low-cost, open-source, smart microscopes enables more researchers to conceive and execute optimized or more complex experiments. Here we present the OpenFlexure Delta Stage, a 3D-printed microscope designed for researchers. Powered by the OpenFlexure software stack, it is capable of performing automated experiments. The design files and assembly instructions are freely available under an open licence. Its intuitive and modular design-along with detailed documentation-allows researchers to implement a variety of imaging modes with ease. The versatility of this microscope is demonstrated by imaging biological and non-biological samples (red blood cells with Plasmodium parasites and colloidal particles in brightfield, epi-fluorescence, darkfield, Rheinberg and differential phase contrast. We present the design strategy and choice of tools to develop devices accessible to researchers from lower-income countries, as well as the advantages of an open-source project in this context. This microscope, having been open-source since its conception, has already been built and tested by researchers around the world, promoting a community of expertise and an environment of reproducibility in science.

NPS detection in prison: A systematic literature review of use, drug form, and analytical approaches.

This paper presents a systematic literature review on the detection of new psychoactive substances (NPS) in prison settings. It includes the most frequently reported NPS classes, the routes and forms used for smuggling, and the methods employed to analyse biological and non‐biological samples. The search was carried out using MEDLINE (EBSCO), Scopus (ELSEVIER), PubMed (NCBI), and Web of Science (Clarivate) databases, along with reports from the grey literature in line with the PRISMA‐S guidelines. A total of 2708 records were identified, of which 50 met the inclusion criteria. Findings showed the most prevalent NPS class reported in prison was synthetic cannabinoids (SCs). The most frequently reported SCs in non‐biological samples were 4F‐MDMB‐BINACA, MDMB‐4en‐PINACA, and 5F‐ADB. These were smuggled mainly through the postal services deposited on paper or herbal matrices. Concentrations of SCs detected on seized paper ranged between 0.05 and 1.17 mg/cm2. The SCs most frequently reported in biological specimens (i.e., urine, blood, saliva, and wastewater) were 5F‐MDMB‐PICA, 4F‐MDMB‐BINACA, and MDMB‐4en‐PINACA. Concentrations of SCs reported in femoral blood and serum were 0.12–0.48 ng/ml and 34–17 ng/ml, respectively. Hyphenated techniques were predominantly employed and generally successful for the detection of NPS in biological (i.e., LC‐HRMS/MS) and non‐biological samples (i.e., LC‐HRMS/MS and GC–MS). The onsite technique IMS showed promise for detecting SCs in various forms; however, immunoassays were not recommended. Future work should focus on accurate in‐field detection of SCs deposited on paper and in urine and saliva to improve real‐time decision‐making, as well as wastewater and air monitoring for overall drug use trends.

Lateral image reconstruction of optical coherence tomography using one-dimensional deep deconvolution network.

Optical coherence tomography (OCT) is a cross-sectional imaging method utilizing a low coherence interferometry. The lateral resolution of the OCT is limited by the numerical aperture (NA) of the imaging lens. Using a high NA lens improves the lateral resolution but reduces the depth of focus (DOF). In this study, we propose a method to improve the lateral resolution of OCT images by end-to-end training of a deep 1-D deconvolution network without use of high-resolution images. To improve the lateral resolution of the OCT, we trained the 1-D deconvolution network using lateral profiles of OCT images and the beam spot size. We used our image-guided laparoscopic surgical tool (IGLaST) to acquire OCT images of nonbiological and biological samples ex vivo. The OCT images were then blurred by applying Gaussian functions with various full width half maximums ranging from 40to 160 µm. The network was trained using the blurred OCT images as input and the non-blurred original OCT images as output. We quantitatively evaluated the developed network in terms of similarity and signal-to-ratio (SNR), using in-vivo images of mesenteric tissue from a porcine model that was not used for training. In addition, we performed knife-edge tests and qualitative evaluation of the network to show the lateral resolution improvement of ex-vivo and in-vivo OCT images. The proposed method showed an improvement of image quality on both blurred images and non-blurred images. When the proposed deconvolution network was applied, the similarity to the non-blurred image was improved by 1.29 times, and the SNR was improved by 1.76 dB compared to the artificially blurred images, which was superior to the conventional deconvolution method. The knife-edge tests at distances at 200 to 1000 µm from the imaging probe showed an approximately 1.2 times improvement in lateral resolution. In addition, through qualitative evaluation, it was found that the image quality of both ex-vivo and in-vivo tissue images was improved with clear structure and less noise. This study showed the ability of the 1-D deconvolution network to improve the image quality of OCT images with variable lateral resolution. We were able to train the network with a small amount of data by constraining the network in 1-D. The quantitative evaluation showed better results than conventional deconvolution methods for various amount of blurring. Qualitative evaluation showed analogous results with quantitative results. This simple yet powerful image restoration method provides improved lateral resolution and suppresses background noise, making it applicable to a variety of OCT imaging applications.

Stokes Dynamic Polarimeter for Non-Organic and Organic Samples Characterization.

The light polarization properties provide relevant information about linear–optical media quality and condition. The Stokes–Mueller formalism is commonly used to represent the polarization properties of the incident light over sample tests. Currently, different Stokes Polarimeters are mainly defined by resolution, acquisition rate, and light to carry out accurate and fast measurements. This work presents the implementation of an automatic Stokes dynamic polarimeter to characterize non-biological and biological material samples. The proposed system is configured to work in the He-Ne laser beam’s reflection or transmission mode to calculate the Mueller matrix. The instrumentation stage includes two asynchronous photoelastic modulators, two nano-stepper motors, and an acquisition data card at 2% of accuracy. The Mueller matrix is numerically calculated by software using the 36 measures method without requiring image processing. Experiments show the efficiency of the proposed optical array to calculate the Mueller matrix in reflection and transmission mode for different samples. The mean squared error is calculated for each element of the obtained matrix using referenced values of the air and a mirror. A comparison with similar works in the literature validates the proposed optical array.

Absolute Configuration of Aliphatic Hydrocarbon Enantiomers Identified by Gas Chromatography: Theorized Application for Isoprenoid Alkanes and the Search of Molecular Biosignatures on Mars

Acyclic saturated hydrocarbon enantiomers were resolved by gas chromatography using a β-cyclodextrin-based chiral stationary phase. The stereospecific synthesis of single enantiomers of 4-methyloctane allowed to assign the absolute stereochemical configuration to the resolved enantiomers. Data show that the (S)-4-methyloctane shows higher chromatographic retention as compared to the (R)-4-methyloctane due to stronger van der Waals interactions with the β-cyclodextrin chiral selector. This introductive research presents future prospects for the separation of stereoisomers of larger branched hydrocarbons. We discuss the importance of chiral hydrocarbons, more precisely the stereochemistry of the isoprenoid alkanes pristane and phytane, as potential biosignatures stable on geological timescales. The origins of pristane and phytane in Earth sediments are presented, and we detail the implications for the search of extinct or extant life on Mars. The data presented here will help to systematically investigate the chirality of hydrocarbon enantiomers in biological and nonbiological samples and in samples to be analyzed by the ESA’s ExoMars rover to trace the chiral precursors of life in 2023.

Role of silver nanoparticles in fluorimetric determination of urea in urine samples

Herein, an economical, analytical and sensitive method was established for the fluorometric determination of urea using freshly prepared silver nanoparticles (Ag-NPs) in real urine samples. The standard addition and second-order derivative methods were selected for the ongoing research work to eliminate the possible effect of interferences in a real environment. In this work, Ag-NPs were prepared by reducing silver nitrate salt in the presence of 1,3-di-(1H-imidazole-1-yl) −2-propanol (DIPO) in an aqueous medium. Urea in the urine samples was successfully determined through the complexation of Ag-NPs with urea molecules. The results revealed high percent recovery with ± RSD of urea in the three different urine samples, where percent recoveries by spectrofluorometric standard addition were 99.77 ± 3.4, 100.24 ± 5.1, 100.93 ± 2.8 and that is by the spectrofluorometric second-order derivative method were 103.57 ± 2.4, 101.8 ± 1.3, 98 ± 3.2, respectively. The successful application of these analytical methods in the spectrofluorometric determination of urea in urine samples can accumulate further addition in the effects and possible role of Ag-NPs in the determination of biological molecules in biological and non-biological samples in the scientific as well as clinical fields.

A Validated High-Pressure Liquid Chromatography (HPLC) Method for Molnupiravir

Molnupiravir is an approved antiviral drug that inhibits RNA replication of viruses. It is approved recently (November 2021) for the treatment of infectious diseases caused by SARS-CoV-2. However, it is reported that Molnupiravir is a nucleoside analogue and shown that nucleoside analogues are reagents that resemble the structure of natural nucleosides. It is widely applied in antiviral and anticancer therapy. Therefore, there is a general need appeared for an efficient, fast, simple, and validated analytical assay method for the quantification of this new product in any samples. We report here that an HPLC method was developed, optimized, and validated for molnupravir. The developed method was found to be easy to apply, cheap, and time-saving. Isocratic elution with 10mM Phosphate Buffer pH:7 / Acetonitrile mixture (80:20) with a Phenomenex C18 column was performed and a photodiode array detector was used for the detection. The total time for the analysis was only 10 minutes. The method was found to be selective, linear, accurate, reproducible, and robust. This proposed method can be easily adapted for molnupravir analyses in pharmaceutical products or in any other biological or non-biological samples.

Speckle-free laser projection structured illumination microscopy based on a digital micromirror device

In the structured illumination microscopy (SIM) family, interferometric implementations using traditional physical gratings or advanced liquid crystal on silicon spatial light modulators are popular but have the disadvantages of expensive and limited speed. A promising alternative of a digital micromirror device (DMD) has improved the situation for its lower cost and higher speed, furthermore, it has contributed to the proposal of a simple and compact projection DMD-SIM. However, the projection DMD-SIM method is accused of erroneously measuring the resolution because of the scattering characteristic of gold beads, despite the inferior experimental resolution that is because of the low fringe contrast and the resulting low signal-to-noise ratio (SNR). As an improvement, we use a high-brightness laser for illumination to achieve higher SNR, and the accompanying problems of speckle and inhomogeneity originating from the laser’s high coherence are solved by a high-frequency phase-randomization deformable mirror in conjunction with a square-core multimode fiber, which does not limit the image acquisition speed and with fewer energy losses compared to the existing methods. Also, in terms of the problem of low SNR, we apply a parallel-iteration Richardson–Lucy deconvolution algorithm for SIM reconstruction to further improve the imaging performance based on ensuring the resolution. Based on these advances, we image fluorescent nanoparticles and other non-biological and biological fluorescent samples, and the experimental results demonstrate the improved imaging performance of our modified system.

Imperative role of electron microscopy in toxicity assessment: A review.

Electron microscope (EM) was developed in 1931 and since then microscopical examination of both the biological and non-biological samples has been revolutionized. Modifications in electron microscopy techniques, such as scanning EM and transmission EM, have widened their applicability in the various sectors such as understanding of drug toxicity, development of mechanism, criminal site investigation, and characterization of the nano-molecule. The present review summarizes its role in important aspects such as toxicity assessment and disease diagnosis in special reference to SARS-COV2. In the biological system, EM studies have elucidated the impact of toxicants at the ultra-structural level in various tissue in conformity to physiological alterations. Thus, EM can be concluded as an important tool in toxicity assessment and disease prognosis.