Study of erythrocyte sedimentation in human blood through the photoacoustic signals analysis

Introduction

In this study, we utilized the pulsed photoacoustic (PA) technique to analyze globular sedimentation in whole human blood, with a focus on distinguishing between healthy individuals and those with hemolytic anemia.

Methods

Blood samples were collected from both healthy individuals (women and men) and those with hemolytic anemia, and temporal and spectral parameters of PA signals were employed for analysis.

Results

Significant differences (p < 0.05) were observed in PA metrics between the two groups. The proposed spectral analysis allowed significant differentiation within a 25-minute measurement window. Anemic blood samples exhibited higher erythrocyte sedimentation rate (ESR) values, indicating increased erythrocyte aggregation.

Discussion

This study underscores the potential of PA signal analysis in ESR assessment as an efficient method for distinguishing between healthy and anemic blood, surpassing traditional approaches. It represents a promising contribution to the development of precise and sensitive techniques for analyzing human blood samples in clinical settings.

Red fluorescent benzothiadiazole derivative loaded in different nanoformulations: Optical properties and their use in bio-imaging

Fluorophores with optimized nonlinear optical properties have become prominent as contrast labels in laser scanning microscopy (LSM). The purpose of this work is to report on a novel benzothiadiazole derivative, namely 4,7-bis(5-((9,9-dioctyl-9H-fluoren-2-yl)ethynyl)thiophen-2-yl)benzo[c][1,2,5]thiadiazole (EFBT) and its optical performance when it is loaded into organic nanostructures intended as labels for LSM. Four different nanostructured labels were prepared: i) EFBT-loaded silica nanoparticles (SiNPs); ii) folate-bioconjugated SiNPs (SiNPs-FA); iii) EFBT-loaded PEGylated nanoparticles (NPs-PEG); and iv) EFBT-loaded folate-terminated PEGylated nanoparticles (NPs-PEG-FA). All these nanostructures are reported through a comparative study of their linear and nonlinear optical properties, including their performance as exogenous label agents in the cervical cancer cell line HeLa. This assessment of the performance of a specific fluorophore loaded into different nanostructured matrices (labels), and fairly compared under the same characterization conditions, including the LSM settings, is less common while previous reports had focused in comparing silica and PEGylated nanoparticles but loaded with different fluorophores. The results show that the internal molecular organization into each type of organic nanostructure impacted differently the properties of EFBT, where the silica matrix tend to preserve the optical performance of the fluorophore by preventing intermolecular interactions; in contrast, PEGylated nanoparticles favored molecular interactions and introduced non-radiative decay channels that degrades drastically the optical performance. Nevertheless, the use of functionalized ends entities produced a better cellular label uptake with PEGylated that with silica nanoparticles. In overall, the NPs-PEG-FA label produced the best HeLa imaging.

Studies of the transition between amplified spontaneous emission and optical lasing in ultrahigh-Q polymeric micro-pedestals

In this work, we demonstrate the properties of Rhodamine B-doped polymeric cylindrical microlasers to perform either as gain amplification devices through amplified spontaneous emission (ASE) or as optical lasing gain devices. A study based on different %wt concentrations of microcavity families with distinct geometrical features demonstrates the characteristic dependence on either gain amplification phenomena. Principal component analysis (PCA) discriminates the relationship between the main ASE and lasing properties and the geometrical aspects of the cavity families. ASE and optical lasing thresholds were found, respectively, as low as 0.2 μJcm^-2 and 0.1 μJcm^-2 passing the best-reported microlaser performances in literature for cylindrical cavities, even in comparison with those based on 2D patterns. Moreover, our microlasers showed ultrahigh Q-factor of ∼3 × 10⁶, and for the first time, to the best of our knowledge, a visible emission comb constituted by above a hundred peaks at 40 μJcm^-2 with a registered free spectral range (FSR) of 0.25 nm corroborated through the whispery gallery mode (WGM) theory.

Image reconstruction algorithm for laser-induced ultrasonic imaging: The single sensor scanning synthetic aperture focusing technique

This paper aims to implement a laser-induced ultrasound imaging reconstruction method based on the delay-and-sum beamforming through the synthetic aperture focusing technique (SAFT) for a circular scanning, performed with a tomograph that had one acoustic sensor and a system that rotates the sample around a fixed axis. The proposed method, called the Single-sensor Scanning Synthetic Aperture Focusing Technique, considers the size of the sensor and the detection procedure inside the SAFT's algebra. This image reconstruction method was evaluated numerically, using the Green function for the laser-induced ultrasound wave equation to generate a forward problem, and experimentally, using a solid object of polylactic acid, and a Sprague-Dawley rat heart located in a tissue-mimicking phantom. The resulting images were compared to those obtained from the time reversal and the conventional delay-and-sum reconstruction algorithms. The presented method removes the sidelobe artifacts and the comet tail sign, which produces a more distinguishable target on the image. In addition, the proposed method has a faster performance and lower computational load. The implementation of this method in photoacoustic microscopy techniques for image reconstruction is discussed.

Laser-induced sound pinging for the rapid determination of total sugar or sweetener content in commercial beverages

We recently reported on fixed-path length laser-induced sound pinging (FPL-LISP) as a rapid photoacoustic technique employing an inexpensive benchtop tattoo-removal laser for reliably determining the speed of sound in low-volume fluids. In this contribution, we demonstrate the capacity of FPL-LISP to analyze representative commercial beverages for their natural or artificial sweetener contents. As a benchmark, the speed of sound was determined for solutions of sugars (glucose, fructose, sucrose), mock high fructose corn syrup (HFCS-55), and 12 household sweeteners (culinary sugars, syrups, honey, molasses) across the concentration range of 1-20% w/v in water, simulating the typical sweetener range found in commercial soft drinks. The setup was then employed to estimate sweetener contents of 26 popular commercial beverages using the HFCS-55 standard curve as a training data set. Our results are remarkably consistent with the label values for these representative commercial beverages, in spite of the fact that some beverages clearly employ a sweetener other than HFCS-55 or a proprietary blend, suggesting the excellent potential of the FPL-LISP setup as a quick screening tool well-suited to quality control and real-time assessment in the beverage and fermentation industrial sectors. The proposed approach represents a significant improvement over many existing methods on the basis of measurement time (down to 1 s, which can be considered real time for many applications), lenient sample requirements (tens of microliters to 1 mL), robust and user-friendly analysis, practical considerations (e.g., economical, minimal service and maintenance concerns), and prospects for advancing both online monitoring and fully portable versions of this instrumentation.

Low-cost fabrication of microlasers based on polymeric micropedestals

Our current work exploits direct laser writing (DLW) and low one-photon absorption (LOPA) in a low-cost three-dimensional optical fabrication system designed to print micrometric polymeric structures. Micropedestals were obtained by focusing a laser beam on a photoresist layer deposited on a silica glass substrate. Subsequent coating with rhodamine 6G dye allows these pedestals to function as microlasers upon optical excitation at 532 nm. Our microlasers, with a diameter of ∼53µm and a height of ∼40µm, exhibit a broad fluorescence peak in the spectral range 540-600 nm, in addition to narrow lasing peaks, exhibiting quality factors Q exceeding 2000 and a lasing threshold of ∼5µJcm^-2. The observed free spectral range associated with the lasing peaks of ∼1.3nm is consistent with simulations, which we include in this paper. In addition, we present simulations for the longitudinal shift of the patterning laser spot, which occurs particularly for relatively thick photoresist layers, coupled with a large index contrast at the photoresist top surface. Such a shift could introduce errors in the resulting microfabricated structures if left unaccounted for. We hope that our work will contribute to the development of microlasers for various photonic applications, particularly if dimensions can be reduced, for on-chip optical communications and data processing.

Spectrophotometric analysis at the single-cell level: elucidating dispersity within melanic immortalized cell populations

The widely held notion that melanin-containing cells are uniform in both size and optical characteristics is demonstrably false.

Optical Photoacoustic Detection of Circulating Melanoma Cells In Vitro

The purpose of this research was to investigate the sensitivity of a system for the detection of circulating melanoma cells based on the thermoelastic properties of melanoma. The method employs photoacoustic (PA) excitation coupled with an optical transducer capable of determining the presence of cells within the circulating system in vitro. The transducer is based on stress wave-induced changes of the optical reflectance of a glass-water interface, probed with a continuous laser beam that is incident at an angle close to the critical angle of total internal reflection. A frequency tripled Nd:YAG laser pumping an optical parametric oscillator was employed to provide 532 nm and 620 nm laser light with a pulse duration of 10 ns. A custom-made flow chamber was used as an excitation and acoustic wave collection device. The targets were a human melanoma cell line HS 936 with an average diameter of about 15 μm. Melanoma cells were suspended in 10 mL of two types of media. The first one was Tyrode's buffer in concentrations ranging from 10 to 50 cells per μL, and the second one included 10(6) healthy white blood cells per mL of Tyrode's buffer. PA pressure waves were detected by an optical stress transducer. Detection trials resulted in a detection threshold of the order of one individual cell, indicating the effectiveness of the proposed mechanism. Results imply the potential to assay simple blood samples, from healthy and metastatic patients, to test the presence of cancerous melanoma providing an unprecedented method for screening metastatic disease.

Raman spectroscopy and multivariate analysis of serum samples from breast cancer patients

Serum samples were studied using Raman spectroscopy and analyzed through the multivariate statistical methods of principal component analysis (PCA) and linear discriminant analysis (LDA). The blood samples were obtained from 11 patients who were clinically diagnosed with breast cancer and 12 healthy volunteer controls. The PCA allowed us to define the wavelength differences between the spectral bands of the control and patient groups. However, since the differences in the involved molecules were in their tertiary or quaternary structure, it was not possible to determine what molecule caused the observed differences in the spectra. The ratio of the corresponding band intensities were analyzed by calculating the p values and it was found that only seven of these band ratios were significant and corresponded to proteins, phospholipids, and polysaccharides. These specific bands might be helpful during screening for breast cancer using Raman Spectroscopy of serum samples. It is also shown that serum samples from patients with breast cancer and from the control group can be discriminated when the LDA is applied to their Raman spectra.

Magnetic field influence on electrical properties of human blood measured by impedance spectroscopy

The impedance spectroscopy technique (IST) was used for studying the effect of a 0.5 T magnetic field on the electrical properties of whole human blood. A Solartron SI 1260 spectrometer was used to measure the impedance spectra of magnetic field exposed blood samples compared to non-exposed samples. An equivalent electrical circuit model, consisting in a resistance Rs in series with a parallel circuit formed by a constant phase element (CPE) and another resistance Rp, is proposed to fit the data in both cases. The experiment used 3 ml human blood samples from 160 healthy donors. A Wilcoxon matched pairs statistical test was applied to the data. The data analysis seems to show a statistically significant increase of the values of resistance Rp (Z = 5.06, P < 0.001) and capacitance CT (Z = 3.32, P < 0.001) of the blood exposed to magnetic field, by approximately 10.4% and 1.9%, respectively.

The colon transit time in different phases of the menstrual cycle: assessed with biomagnetic technique

Twenty measurements of the colon transit time (CTT) were performed by biomagnetic technique in five young women. Subjects were assessed during 12 hours a day for four phases of the menstrual cycle (MC): early follicular (EF), days 1-4 of the MC; late follicular (LF), days 9-14; early luteal (EL), days 15-18; and late luteal (LL), days 23-28 of the MC. Comparison intra and inter-subjects were made. The results of a t test for dependent samples, demonstrate that women with regular MC had higher CTT on LF (3.29 +/- 1.40 m/hr) than on LL phases of the MC (1.28 +/- 0.4 m/hr) t = 3.22, p = 0.04. Also we found differences from EL to LL phases of the MC (4.49 +/- 1.72 m/hr vs. 1.29 +/- 0.35 m/hr, t = 3.05, p = 0.05). However, in a patient with polycystic ovary syndrome (PCOS), we found a CTT of 3.1 m/hr on day 3; 2 m/hr on day 15; and 0.8 m/hr on day 30 of the MC. The time of the magnetic marker displacement was higher on days 3 of the MC, if we compared these values with those from women with regular MC (1.8 +/- 0.67 m/hr). We demonstrate that biomagnetic technique is a powerful method to assess changes in CTT presented in female subjects during the MC. Furthermore, the results found for the CTT in different phases of the MC of the females subjects, are in agreement with those reported by using other techniques.

In vivo measurement of human skin absorption of topically applied substances by a photoacoustic technique

A photoacoustic technique is used for studying topically applied substance absorption in human skin. The proposed method utilizes a double-chamber PA cell. The absorption determination was obtained through the measurement of the thermal effusivity of the binary system substance-skin. The theoretical model assumes that the effective thermal effusivity of the binary system corresponds to that of a two-phase system. Experimental applications of the method employed different substances of topical application in different parts of the body of a volunteer. The method is demonstrated to be an easily used non-invasive technique for dermatology research. The relative concentrations as a function of time of substances such as ketoconazol and sunscreen were determined by fitting a sigmoidal function to the data, while an exponential function corresponds to the best fit for the set of data for nitrofurazona, vaseline and vaporub. The time constants associated with the rates of absorption, were found to vary in the range between 10 and 58 min, depending on the substance and the part of the body.