Molecular structure analysis of ascending aorta aneurysm upon atherosclerosis

Background

The atherosclerotic ascending aorta could represent a potential source of emboli or could be an indicator of atherosclerosis in general with high mortality. The mechanism of aneurysm formation and atherosclerosis of the ascending aorta at the molecular level has not yet been clarified. To approach the mechanism of ascending aortic lesions and mineralization at a molecular level, we used the non-destructive FT-IR, Raman spectroscopy, SEM and Hypermicroscope.

Methods

Six ascending aorta biopsies were obtained from patients who underwent aortic valve replacement (AVR) cardiac surgery. CytoViva (einst inc) hyperspectral microscope was used to obtain the images of ascending aorta. The samples were dissolved in hexane on a microscope glass plate. The FT-IR and Raman spectra were recorded with Nicolet 6700 thermoshintific and micro-Raman Reinshaw (785nm, 145 mwatt), respectively. The architecture of ascending aorta biopsies was obtained by using scanning electron microscope (SEM of Fei Co) without any coating.

Results

FT-IR and Raman spectra showed changes arising from the increasing of lipophilic environment and aggregate formation (Fig. 1). The band at 1744 cm–1 is attributed to aldehyde CHO mode due to oxidation of lipids. The shifts of the bands of the amide I and amide II bands to lower are associated with protein damage, in agreement with SEM data. The bands at about 1170–1000 cm–1 resulted from the C-O-C of advanced glycation products as result of connecting tissues fragmentations and polymerization. The spectroscopic data were analogous with the lesions observed with SEM and hypermicroscopic images.

Conclusions

The present innovate molecular structure analysis showed that upon ascending aorta aneurysm development an excess of lipophilic aggregate formation and protein lesions, changing the elasticity of the aorta's wall. The released Ca2+ interacted mostly with carbonate-terminal of cellular protein chains accelerated the ascending aorta calcifications.

Figure 1. FT-IR and Raman spectra

Funding Acknowledgement

Type of funding source: None

Modified New Zealand rabbit model produces severe aortic valve calcification and stenosis via extracellular membranous particles

Background/Purpose

In aortic valve stenosis calcification begins with nucleation on extracellular vesicles. In order to study early-stage disease, validated animal models are needed. The Drolet rabbit model is relevant due to tricuspid valve, but failed to consistently produce stenosis probably due to regimen administration. We compared a modified rabbit model and investigated the mechanisms and patterns of calcification.

Methods

New Zealand rabbits introduced to normal chaw+1% cholesterol+8750 IUs Vitamin D2/kg (Sigma) daily, in olive oil given in a bisquit vs control animals, for 8 weeks. Aortic valve area (AVA) and mean gradient (meanGr) was assessed with echocardiography (Vivid 7, M3S transducer, GE). At 8 weeks animals were sacrificed and valves were snap-frozen to −80°C. From each animal, one cusp was analyzed with Fourier-Transformed Infrared Spectroscopy (FT-IR, Nicolet 6700 spectrometer, OMNIC 7.3 software), another cusp was processed in alcoholic solution and the third was fixed 0.5 μm thin on 4% PFA; supernatant and tissue respectively examined with multispectral optical imaging. Valves from patients with severe stenosis were used for qualitative comparisons.

Results

At 8 weeks versus baseline, AVA reduced (0.5 cm2 to 0.3 cm2) and meanGr increased (1.1 to 2.95 mmHg, p<0.05), in control was unchanged. FT-IR vibrations in the region of 1800–800 cm–1 demonstrated changes in the protein structure and deposition of CaCO3 and non-hydroxyapatite Ca3(PO4)2 identical to patients' lesions. Multispectral optical imaging of supernatants revealed numerous membranous particles and conductivity analysis indicated calcium cations accumulation on the phospholipids of membrane. The tissue images confirmed the degradations and dendrimer-like depositions of calcium cations most likely on carbonates of amino acids.

Conclusions

The modified high-fat-vitamin D2 rabbit model produces aortic valve stenosis, with chemically identical mineralization to human lesion. Multispectral photonics demonstrate the presence of calcified membranous extracellular particles, a hallmark of cardiovascular calcification. Dendrimer-like depositions correspond to growing deposits. The model is suitable as a research platform purposed for aortic valve stenosis.

Figure 1. A: Image from alcoholic solution supernatant. The bright spots have high conductivity due to Ca 2+ deposition. B: ImageJ surface plot of circulated region confirms calcification. C: 3D-plot illustrates mineralization of membranes. D: 3D-plot of human aortic valve. E: Hypermicroscopic image of rabbit valve tissue: dendrimer-like and mineral cation deposits.

Funding Acknowledgement

Type of funding source: Public Institution(s). Main funding source(s): National and Kapodistrian University of Athens, Greece; Concordia University, Montreal, Canada

Tuning of Morphology and Stability of Gold Nanostars Through pH Adjustment

In this study, the morphology and stability of gold nanostars (AuNSs) were investigated under different pH environments. The surface morphologies and plasmonic properties were observed for nanostars (NSs) deposited on glass substrates, using SEM and ultraviolet and visible (UV-Vis) spectroscopy. It is found that gold nanostars can be readily stabilized just by adjusting the initial pH condition of the growth solution. The particle size distribution of gold nanostars under different pH environments has been investigated using UV-Vis spectroscopy and found to be highly dependent on pH. At the optimal pH of 11, the gold nanostars are highly monodisperse, they have longer branches and the Au Localized Surface Plasmon Resonance band (LSPR) at 720 nm. For other pH conditions, particles are non-uniform and polydisperse, showing a red-shift of the plasmon peak due to aggregation and a large particle size distribution. Time-dependent UV-Vis spectra studies hypothesize the pH dependent stabilization mechanism, where the formation and stabilization of AuNS were affected greatly by the aggregation induced by pH of the growth solution. The information obtained in this study can be used to design stable gold nanostars with longer shelf life for biosensing applications.

Nano-Bio Interactions of Extracellular Vesicles with Gold Nanoislands for Early Cancer Diagnosis

Extracellular vesicles or exosomes are membrane encapsulated biological nanometric particles secreted virtually by all types of cells throughout the animal kingdom. They carry a cargo of active molecules to proximal and distal cells of the body as mechanism of physiological communication, to maintain natural homeostasis as well as pathological responses. Exosomes carry a tremendous potential for liquid biopsy and therapeutic applications. Thus, there is a global demand for simple and robust exosome isolation methods amenable to point-of-care diagnosis and quality control of therapeutic exosome manufacturing. This can be achieved by molecular profiling of the exosomes for use with specific sets of molecular-markers for diagnosis and quality control. Liquid biopsy is undoubtedly the most promising diagnosis process to advance "personalized medicine." Currently, liquid biopsy is based on circulating cancer cells, cell free-DNA, or exosomes. Exosomes potentially provide promise for early-stage diagnostic possibility; in order to facilitate superior diagnosis and isolation of exosomes, a novel platform is developed to detect and capture them, based on localized surface plasmon resonance (LSPR) of gold nanoislands, through strong affinity between exosomes and peptide called Venceremin or Vn96. Physical modeling, based on the characteristics of the gold nanoislands and the bioentities involved in the sensing, is also developed to determine the detection capability of the platform, which is optimized experimentally at each stage. Preliminary results and modeling present a relationship between the plasmonic shift and the concentration of exosomes and, essentially, indicate possibilities for label-free early diagnosis.

The effect of hydrogen nanobubbles on the morphology of gold-gelatin bionanocomposite films and their optical properties

Gold-gelatin bionanocomposite films are prepared by the reduction of gold ions by sodium borohydride in an aqueous solution. It is shown that both the solution and the films on glass substrates contain entrapped hydrogen micro- and nanobubbles with diameters in the range of 200 nm-3 μm. The optical properties of gold nanoparticles in the presence of gelatin and hydrogen nanobubbles are measured and simulated by using the discrete dipole approximation method. The composite films having micro- and nanobubble inclusions have been found to be very stable. The calculated localized surface plasmon resonance band is found in agreement with the experimental band position only when the presence of hydrogen bubbles around the gold nanoparticles is taken into account. The different morphological features engendered by the presence of the bubbles in the film (gelatin receptacles for the nanoparticles, gelatin hemispheres raised by the bubbles under the surface, cavities on the surface of the film, etc) are described in detail and considered for potential applications. This work is highly relevant to the new and exciting topic of nanobubbles on surfaces and interfaces.

Nano-islands integrated evanescence-based lab-on-a-chip on silica-on-silicon and polydimethylsiloxane hybrid platform for detection of recombinant growth hormone

Integration of nano-materials in optical microfluidic devices facilitates the realization of miniaturized analytical systems with enhanced sensing abilities for biological and chemical substances. In this work, a novel method of integration of gold nano-islands in a silica-on-silicon-polydimethylsiloxane microfluidic device is reported. The device works based on the nano-enhanced evanescence technique achieved by interacting the evanescent tail of propagating wave with the gold nano-islands integrated on the core of the waveguide resulting in the modification of the propagating UV-visible spectrum. The biosensing ability of the device is investigated by finite-difference time-domain simulation with a simplified model of the device. The performance of the proposed device is demonstrated for the detection of recombinant growth hormone based on antibody-antigen interaction.

Enhanced bio-molecular interactions through recirculating microflows

A recirculating microfluidic platform has been developed for carrying out optical bio-detection. The present device can be used for passive mixing of the biological species with the microfluidic channel without immobilisation, through appropriate design and flow control. The feasibility of bio-detection using the present setup has been demonstrated through the method of fluorescence and the experiments were carried out with Antisheep Antibody (AB) tagged with Alexafluor 647 (AF647) fluorophore particles. By controlling the fluid flow, it was possible to isolate AB separately into a recirculation zone within the microfluidic channel, thereby enabling qualitative and quantitative bio-detection. Finite element modelling of the flow behaviour has been carried out and the results were similar to the results of flow visualisation obtained with tagged antibody particles. The present work thus provides confidence in using the hybrid integrated device for in situ rapid biomedical detection of biological pairs or individual specimen in fluorescence-based chemical and biological sensing.

Absorption detection of enzymatic reaction using optical microfluidics based intermittent flow microreactor system

The advantages of integrating microfluidics into photonics-based biosensing for fabricating microreactor type lab-on-a-chip devices carries a lot of advantages, such as smaller sample volume handling, controlled drug delivery and high throughput diagnosis, which is useful for in situ medical diagnosis and point-of-care (POC) testing. A hybrid integrated optical microfluidic system has been developed for the study of single molecules and enzymatic reactions. The method of optical absorption has been employed for biosensing and the feasibility of absorption-based detection on the microfluidic platform has been demonstrated using horseradish peroxidase and hydrogen peroxide, as an example. The results show that the device is useful for the analysis of both the individual chemical specimen and also the study of chemical and biological reaction between two reacting species. The hybrid integration of microfluidics and optical ensembles thus forms the basis for developing the microreactor type lab-on-a-chip device, which would have several important applications in the area of nanobiotechnology.