Scanning Acoustic Microscopy and Time-Resolved Fluorescence Spectroscopy for Characterization of Atherosclerotic Plaques

Determination of the significance of atomic concentration on surface properties of Ba x Mg1-x F2 alloy coatings via microscopic and spectroscopic techniques

Both BaF2 and MgF2 compounds and Ba x Mg1-x F2 alloy thin films were deposited on glass and silicon (Si) substrates in nanometric sizes (100 ± 10 nm) in a high vacuum environment by radio frequency (rf) magnetron sputtering. Using BaF2 (99% purity) and MgF2 (99% purity) target materials and adjusting the power levels applied to these targets, Ba x Mg1-x F2 alloy coatings at different atomic concentrations were formed under the same vacuum conditions. The microstructure and surface characteristics of the samples were analysed with the help of spectroscopic and microscopic methods. For the surface characterization, with scanning acoustic microscopy (SAM), 2-dimensional surface acoustic images of the samples were mapped, the surface acoustic impedance values were determined, and information about the micro hardness of the materials was obtained. Surface roughness values and grain sizes were obtained by taking 3-dimensional surface images of investigated materials using atomic force microscopy (AFM). Average nanometric particle sizes were determined for each sample with scanning electron microscopy (SEM), therefore, information about surface homogeneity was obtained. For the microstructural characterization, quantitative elemental analysis was performed using scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM-EDS), and stoichiometric ratios of atomic compositions were identified. By evaluating the data obtained from the microscopic and spectroscopic measurements, the effect of the atomic concentration parameter on the morphological properties of the material was determined. The usability of the produced binary fluoride alloy thin film coatings is promising for emerging optoelectronic, ceramic industry, biomedical and surface acoustic wave applications.

Design and Fabrication of Environmentally Responsive Nanoparticles for the Diagnosis and Treatment of Atherosclerosis

Cardiovascular disease poses a significant threat to human health in today's society. A major contributor to cardiovascular disease is atherosclerosis (AS). The development of plaque in the affected areas involves a complex pathological environment, and the disease progresses rapidly. Nanotechnology, combined with emerging diagnostic and treatment methods, offers the potential for the management of this condition. This paper presents the latest advancements in environment-intelligent responsive controlled-release nanoparticles designed specifically for the pathological environment of AS, which includes characteristics such as low pH, high reactive oxygen species levels, high shear stress, and multienzymes. Additionally, the paper summarizes the applications and features of nanotechnology in interventional therapy for AS, including percutaneous transluminal coronary angioplasty and drug-eluting stents. Furthermore, the application of nanotechnology in the diagnosis of AS shows promising real-time, accurate, and continuous effects. Lastly, the paper explores the future prospects of nanotechnology, highlighting the tremendous potential in the diagnosis and treatment of atherosclerotic diseases, especially with the ongoing development in nano gas, quantum dots, and Metal-Organic Frameworks materials.

Examination of annulus fibrosus and nucleus pulposus in cervical and lumbar intervertebral disc herniation patients by scanning acoustic microscopy, scanning electron microscopy and energy dispersive spectroscopy

Intervertebral disc herniation (IVDH) is observed in humans as a result of the alteration of annulus fibrous (AF) and nucleus pulposus (NP) tissue compositions in intervertebral discs. In this study, we studied the feasibility of scanning acoustic microscopy (SAM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) in characterizing the herniated segments of AF and NP tissues from male and female patients. SAM determined the acoustic property variations in AF and NP tissues by calculating the acoustic impedance values of samples of 15 patients. SEM obtained higher resolution images and EDS made elemental analysis of the specimen. Consequently, we suggest that these techniques have the potential to be combined for the investigation and removal of the disrupted AF and NP tissues with micrometer resolution in clinics.

Fluorescence Spectroscopy: A Useful Method to Explore the Interactions of Small Molecule Ligands with DNA Structures

Small molecule ligands-DNA interactions have recently received a lot of attention in the fields of life sciences, medicine, and chemical sciences. To decode these interactions, many strategies have been developed. DNA is the primary target for a wide range of drugs that may interact with DNA in particular or non-specific ways and impact its activities. Fluorescence spectroscopy is a highly advanced and non-invasive technology for measuring the concentrations of substrates and products or identifying characteristic processing states. Small molecule ligands-DNA interaction studies are beneficial not only in comprehending the method of interaction, but also in synthesizing DNA-targeted particular drugs. Several small compounds that bind to DNA are clinically established therapeutic medicines, while their specific mechanism of action is unknown. Figuring out their molecular recognizing patterns is the only way to construct innovative compounds that can target specific DNA sequences with strong affinities. This book chapter will mostly explore several fluorescence spectroscopic methodologies used to investigate interactions between small molecule ligands and DNA. In addition, we provide many approaches for determining a drug's binding mode with DNA. These strategies produce data that is both trustworthy and easy to comprehend. All of the knowledge gained by studying these fluorescence spectroscopies are supposed to lead to the development of more efficient new pharmaceuticals that might aid in the treatment of diseases.

Atrial fibrillation designation with micro-Raman spectroscopy and scanning acoustic microscope

Atrial fibrillation (AF) is diagnosed with the electrocardiogram, which is the gold standard in clinics. However, sufficient arrhythmia monitoring takes a long time, and many of the tests are made in only a few seconds, which can lead arrhythmia to be missed. Here, we propose a combined method to detect the effects of AF on atrial tissue. We characterize tissues obtained from patients with or without AF by scanning acoustic microscopy (SAM) and by Raman spectroscopy (RS) to construct a mechano-chemical profile. We classify the Raman spectral measurements of the tissue samples with an unsupervised clustering method, k-means and compare their chemical properties. Besides, we utilize scanning acoustic microscopy to compare and determine differences in acoustic impedance maps of the groups. We compared the clinical outcomes with our findings using a neural network classification for Raman measurements and ANOVA for SAM measurements. Consequently, we show that the stiffness profiles of the tissues, corresponding to the patients with chronic AF, without AF or who experienced postoperative AF, are in agreement with the lipid-collagen profiles obtained by the Raman spectral characterization.

Aortic aneurysm evaluation by scanning acoustic microscopy and Raman spectroscopy

Aortic aneurysm is observed as a result of the extensive alteration in the elasticity of the aortic wall due to the breakdown of elastin and collagen. In this study, we studied the feasibility of scanning acoustic microscopy (SAM) and Raman spectroscopy (RS) in characterizing the dilated segments of the aorta from male and female patients with aortic aneurysm. SAM determined the acoustic property variation in the aorta by calculating the acoustic impedance values of aorta samples of 18 patients. RS determined the disease states by analyzing the chemical variation especially in the peaks related to elastin and collagen using the k-means classification method. Consequently, we assume that combining these two techniques in clinics will help to investigate the dilated segment of the aorta with micrometer resolution, which will reduce the possibility of new aneurysm formation due to a segment not excised during the surgery.

Determination of modifications in rat liver due to phthalate uptake by SAM, RS, and ICP-OES

The use of phthalates as plasticizers has been omnipresent, especially in cosmetics and food packaging, despite the proven effects on some organs of humans and animals. Therefore, alterations in living organisms due to phthalate exposure attract the attention of many scientists. Here, we demonstrate a mechanical and chemical investigation of the mentioned effects of di(2-ethylhexyl)phthalate (DEHP) and dibutyl phthalate (DBP) on rat liver by utilizing scanning acoustic microscopy (SAM), Raman spectroscopy (RS) and inductively coupled plasma optical emission spectrometry (ICP-OES) for the first time in the literature, as far as we know. The combined analysis gives insights into the degree of modification in the tissue components and which chemicals lead to these modifications. Our study shows that the acoustic impedance values of tissues of DEHP and DBP delivered mother rats are higher than those of tissues of the control mother rat, while the acoustic impedance values of tissues of offspring rats of DEHP and DBP delivered mother rats do not differ significantly from those of tissues of the control offspring rats of the control mother rat. Besides, RS analysis shows how the incorporation of DEHP into liver tissues changes the configuration and conformation of lipids and fatty acids. ICP-OES results show increased element levels within the tissues of DEHP and DBP delivered rats. Therefore, we can say that phthalates cause modifications within the liver. This study is a preliminary effort to investigate tissues with a mechano-chemical probe.

In Vivo Tracking of Tissue Engineered Constructs

To date, the fields of biomaterials science and tissue engineering have shown great promise in creating bioartificial tissues and organs for use in a variety of regenerative medicine applications. With the emergence of new technologies such as additive biomanufacturing and 3D bioprinting, increasingly complex tissue constructs are being fabricated to fulfill the desired patient-specific requirements. Fundamental to the further advancement of this field is the design and development of imaging modalities that can enable visualization of the bioengineered constructs following implantation, at adequate spatial and temporal resolution and high penetration depths. These in vivo tracking techniques should introduce minimum toxicity, disruption, and destruction to treated tissues, while generating clinically relevant signal-to-noise ratios. This article reviews the imaging techniques that are currently being adopted in both research and clinical studies to track tissue engineering scaffolds in vivo, with special attention to 3D bioprinted tissue constructs.

Determination of Ultrastructural Properties of Human Carotid Atherosclerotic Plaques by Scanning Acoustic Microscopy, Micro-Computer Tomography, Scanning Electron Microscopy and Energy Dispersive X-Ray Spectroscopy

Microcalcification is the precursor of vulnerability of plaques in humans. Visualization of such small structures in vivo with high spatial resolution is an unsolved issue. The goal of this study is to evaluate the potential of scanning acoustic microscopy (SAM) in the determination of atherosclerotic plaques with calcifications by validating this technique with micro-computer tomography (micro-CT), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The fibrocalcific plaques were obtained from 12 different patients and initially examined with micro-CT. The images exhibited calcifications within these plaques. For imaging with SAM, approximately 5 μm thick slices were prepared. Sound speed values within calcified regions were measured to be greater than the ones in collagen-rich regions. These fibrocalcific plaques were also examined with SEM and EDS revealing collagen and calcium deposition within these samples. The consistency of the results obtained by all of the modalities involved in our study is an indication of the potential of SAM as a clinical tool for the diagnosis of vulnerable plaques.