Search

Assessment of molecular changes by PET has introduced a new paradigm in atherosclerosis imaging, which has traditionally relied on anatomic changes visualized by conventional angiography or computed tomography. The use of 18F-fluorodeoxyglucose (FDG) to identify atherosclerotic changes in the vessel wall was first described more than 2 decades ago. Since then, PET tracers targeting macrophage activity, neoangiogenesis, smooth muscle activity, and other aspects of atherogenic changes have been proposed. The evolving roles of PET tracers including frontrunners FDG and 18F-sodium fluoride, which show arterial wall inflammation and microcalcification, respectively, are discussed.

Positron emission tomography (PET) imaging with18 F-fluorodeoxyglucose (FDG) repre-sents a method of detecting and characterizing arterial wall inflammation, with potential applications in the early assessment of vascular disorders such as atherosclerosis. By portraying early-stage molecular changes, FDG-PET findings have previously been shown to correlate with atherosclerosis progression. In addition, recent studies have suggested that microcalcification revealed by18 F-sodium fluoride (NaF) may be more sensitive at detecting atherogenic changes compared to FDG-PET. In this review, we summarize the roles of FDG and NaF in the assessment of atherosclerosis and discuss the role of global assessment in quantification of the vascular disease burden. Further-more, we will review the emerging applications of FDG-PET in various vascular disorders, including pulmonary embolism, as well as inflammatory and infectious vascular diseases.

Cell-derived vesicles (CDVs) have been investigated as an alternative to exosomes. Here, we generated CDVs from Prokineticin receptor 1 (PROKR1) overexpressing HEK293T cells using micro-extrusion. More than 60 billion PROKR1-enriched CDV (PROKR1Tg CDVs) particles with canonical exosome properties were recovered from 107 cells. With 25 μg/mL of PROKR1Tg CDVs, we observed delivery of PROKR1, significant reduction of apoptosis, and myotube formation in C2C12Prokr1−/− myoblasts that have lost their myogenic potential but underwent apoptosis following myogenic commitment. Expression levels of early and late myogenic marker genes and glucose uptake capacity were restored to equivalent levels with wild-type control. Furthermore, PROKR1Tg CDVs were accumulated in soleus muscle comparable to the liver without significant differences. Therefore, CDVs obtained from genetically engineered cells appear to be an effective method of PROKR1 protein delivery and offer promise as an alternative therapy for muscular dystrophy.

Gelatin Type A (GA) and sodium alginate (SA) complexes were explored to encapsulate epidermal growth factor (EGF), and thereby to circumvent its proteolytic degradation upon topical application to chronic wounds. Phase diagrams were constructed based on turbidity as a function of GA to SA ratio and pH. Various GA-SA mixtures were compared for polydispersity index, zeta potential, Z-average, and ATR-FTIR spectra. Trypsin digestion and human dermal fibroblast scratch wound assay were done to evaluate the effects of EGF encapsulation. The onset pH values for coacervation and precipitation were closer together in high molecular weight GA (HWGA)-SA reaction mixtures than in low molecular weight GA (LWGA)-SA, which was attributed to strong H-bonding interactions between HWGA and SA probed by ATR-FTIR. EGF incorporation in both HWGA-SA precipitates and LWGA-SA coacervates below the isoelectric point of EGF, but not above it, suggests the contribution of electrostatic interactions between EGF and SA. EGF encapsulated in LWGA-SA coacervates was effectively protected from trypsin digestion and showed better in vitro scratch wound activity compared to free EGF. LWGA-SA coacervates are suggested as a novel delivery system for topical application of EGF to chronic wounds.

Complex coacervates based on natural biopolymers have been explored as a protein delivery system to provide controlled release of loaded protein and circumvent the proteolytic degradation in chronic wounds. The coacervates composed of gelatin A (GA) and sodium alginate (SA) were optimized with respect to turbidity, size, zeta potential, and polydispersity index. Bovine serum albumin (BSA), a model protein, was effectively encapsulated in the coacervates, resulting in protection from trypsin digestion and controlled release. In contrast, EGF was not encapsulated in the same coacervates. Striking difference in the encapsulation efficiencies of BSA and EGF, despite their similar net charges, was attributed to their different levels of binding to GA based on the surface plasmon resonance (SPR) biosensor analysis. In conclusion, GA and SA coacervates can protect the encapsulated protein from proteolytic degradation, demonstrating its potential as a delivery system in the chronic wounds. SPR biosensor is proposed as an analytical tool to study the interactions between polymers and proteins in association with encapsulation efficiency in complex coacervation. The results of EGF studies suggested that GA was not a suitable polymer for EGF encapsulation and therefore, further investigation would be needed to find suitable polymer systems for improved encapsulation efficiency.

Exhaled breath is a body secretion, and the sampling process of this is simple and cost effective. It can be non-invasively collected for diagnostic procedures. Variations in the chemical composition of exhaled breath resulting from gaseous exchange in the extensive capillary network of the body are proposed to be associated with pathophysiological changes. In light of the foreseeable potential of exhaled breath as a diagnostic specimen, we used gas chromatography and mass spectrometry (GC-MS) to study the chemical compounds present in exhaled breath samples from patients with Alzheimer's disease (AD), Parkinson's disease (PD), and from healthy individuals as a control group. In addition, we also designed and developed a chemical-based exhaled breath sensor system to examine the distribution pattern in the patient and control groups. The results of our study showed that several chemical compounds, such as 1-phenantherol and ethyl 3-cyano-2,3-bis (2,5,-dimethyl-3-thienyl)-acrylate, had a higher percentage area in the AD group than in the PD and control groups. These results may indicate an association of these chemical components in exhaled breath with the progression of disease. In addition, in-house fabricated exhaled breath sensor systems, containing several types of gas sensors, showed significant differences in terms of the normalized response of the sensitivity characteristics between the patient and control groups. A subsequent clustering analysis was able to distinguish between the AD patients, PD patients, and healthy individuals using principal component analysis, Sammon's mapping, and a combination of both methods, in particular when using the exhaled breath sensor array system A consisting of eight sensors. With this in mind, the exhaled breath sensor system could provide alternative option for diagnosis and be applied as a useful, effective tool for the screening and diagnosis of AD in the near future.

Recent advanced technologies have focused on the development of simple, cost effective, and reliable diagnostic methods for diseases. The combination of improved technology and non-invasive sampling has been proposed as a new approach in medical diagnosis. Thus, we developed a screening-based biosensor with the ion-sensitive field-effect transistor (ISFET) to screen for Alzheimer’s disease (AD) using the human saliva. The biosensor we developed uses a gustatory receptor (Gr5a) expressed in Drosophila Schneider 2 cells to detect the presence of sugar, particularly trehalose, in the saliva of humans. In this study, a total of six human saliva samples, of which five were obtained from AD patients and one from a normal individual without a history of AD were used. Based on the results, the response voltages generated from the human saliva of AD and that of a normal person were distinctively divided into two clusters using the Gr5a-expressed cell-oriented ISFET. This suggests that the content of sugar present in the saliva of AD and the normal person differed. Moreover, the variation of sugar detected might suggest that a sugar-based molecule such as trehalose could be a potential novel biomarker for the progression of AD. Hence, the cell-oriented ISFET developed has great prospects for use as a non-invasive screening device for AD in the near future.

Coagulative necrosis often occurs under hypoxic conditions, causing major limitation in the field of tissue engineering especially those dealing with larger tissues and organs. In this study, a comprehensive work has been performed in developing a tailor made design of a dual layered matrix that can produce oxygen to be utilized in tissue engineering application. Optimizations of protocol, ingredient and condition of the system were carried out specifically based on the responses observed from in vitro studies using L6 rat skeletal muscle cell as a candidate. Oxygen was generated from decomposition of encapsulated hydrogen peroxide. Poly (D,L)-lactide-co-glycolide (PLGA) with molecular weights of 90,000 and 110,000 gmol−1 managed to secure good encapsulation of hydrogen peroxide for this application, while the best stirring time during the encapsulation was found to be 8 hours. The PLGA microspheres were coated with a secondary layer of alginate that was pre-grafted with calatase to form the dual layer system. This dual layered architecture has successfully controlled the release rate of oxygen at an optimum level for the survival of muscle cells under hypoxia condition. It was found that muscle cells have low tolerance limit towards the direct contact with hydrogen peroxide, however the cells maintained high viability within encapsulated hydrogen peroxide in the matrix system. It was observed that 4% of encapsulated hydrogen peroxide in the matrix system can produce efficient amount of oxygen at a controlled release manner to sustain the survival of muscle cells under hypoxic condition.

The field of hair follicle regeneration is advancing rapidly, and there have been a number of major achievements over the last decade. Nonetheless, most of the current technologies are still unable to maintain their in vivo characteristics in vitro. The formation of new hair follicles for the treatment of alopecia using tissue engineering technology is promising; however, little or no work has been attempted in this area so far. In order to enhance the hair inducing ability of epithelial cells and to form the functional epithelial structure, we attempted to fabricate three-dimensional scaffolds by using bladder submucosal membrane (BSM), keratin, hyaluronic acid (HA), and mouse newborn epithelial skin scaffold (NESS). We characterized their properties with respect to the formation of the epithelial structure. The BSM sponge demonstrated the intrinsic activation of melanocytes once we inserted the inductive dermal papilla sphere. We found that the fiber sheet made of keratin enhanced cell spreading and adhesion better than the sheet with HA. The human outer root sheath keratinocytes formed a cluster on the NESS. These scaffolds would be used for the follicular epithelial cell physiology and study for property of them in vitro. This study demonstrated the potential of epithelial cell scaffolds for effective hair regeneration.

Advanced biosensors for diagnostic and clinical applications will require capabilities such as real-time detection or monitoring of physiological changes in vivo in addition to being light weight, small size, highly sensitive, selective, have ease in signal transmission, and stable. The fabrication of a high-performance biosensor can be realized by the development of bioprinting technology. Bioprinting enables high throughput, digital control, and accurate delivery of target material to the specific locations. Also, the sophisticated sensors fabricated by advanced science and technology, including nanosensors, wearable sensors, implantable sensors, and wireless sensors, have opened huge possibilities in understanding phenomena that occur in the body, and can be widely used for translational research. In this chapter, we will review various cutting-edge sensor technologies and bioprinting from the viewpoint of their potential application to biomedical engineering and therapeutics.

Protein is a widely used sensing substrate in the biosensing technology. In the study conducted here, we used odorant binding protein, LUSH from Drosophila as a biosensing substrate in a miniaturized surface plasmon resonance (SPR) sensor. LUSH contains the specific alcohols binding sites, which mediates the detection of alcohols and pheromone. We first modified the surface of the gold sensor chip using the self assembled monolayer in the chloroform solution. The saturated concentration was determined prior to the detection of alcohols and pheromone at various concentrations. The results showed that the LUSH was saturated at 1000 µg/ml on the gold sensor chip. The detection response of LUSH was significant at higher concentration of alcohols. LUSH detected ethanol at concentration • 50%; propanol was detected at • 25% whereas pheromone was detected at • 1.25 µg/µl. The results provide some fundamental information on the potential use of LUSH-based SPR as a simple and easy protein-based sensor in the near future. Keywords: *LUSH, alcohols, pheromone, surface plasmon resonance*

Body fluids are often used as specimens for medical diagnosis. With the advent of advanced analytical techniques in biotechnology, the diagnostic potential of saliva has been the focus of many studies. We recently reported the presence of excess salivary sugars, in patients with Alzheimer's disease (AD). In the present study, we developed a highly sensitive, cell-based biosensor to detect trehalose levels in patient saliva. The developed biosensor relies on the overexpression of sugar sensitive gustatory receptors (Gr5a) in Drosophila cells to detect the salivary trehalose. The cell-based biosensor was built on the foundation of an improved extended gate ion-sensitive field-effect transistor (EG-ISFET). Using an EG-ISFET, instead of a traditional ion-sensitive field-effect transistor (ISFET), resulted in an increase in the sensitivity and reliability of detection. The biosensor was designed with the gate terminals segregated from the conventional ISFET device. This design allows the construction of an independent reference and sensing region for simultaneous and accurate measurements of samples from controls and patients respectively. To investigate the efficacy of the cell-based biosensor for AD screening, we collected 20 saliva samples from each of the following groups: participants diagnosed with AD, participants diagnosed with Parkinson's disease (PD), and a control group composed of healthy individuals. We then studied the response generated from the interaction of the salivary trehalose of the saliva samples and the Gr5a in the immobilized cells on an EG-ISFET sensor. The cell-based biosensor significantly distinguished salivary sugar, trehalose of the AD group from the PD and control groups. Based on these findings, we propose that salivary trehalose, might be a potential biomarker for AD and could be detected using our cell-based EG-ISFET biosensor. The cell-based EG-ISFET biosensor provides a sensitive and direct approach for salivary sugar detection and may be used in the future as a screening method for AD.

The development of potential applications of biosensors using the sensory systems of vertebrates and invertebrates has progressed rapidly, especially in clinical diagnosis. The biosensor developed here involves the use of Drosophila cells expressing the gustatory receptor Gr5a and an ion-sensitive field-effect transistor (ISFET) sensor device. Gustatory receptor Gr5a is expressed abundantly in gustatory neurons and acts as a primary marker for tastants, especially sugar, in Drosophila. As a result, it could potentially serve as a good candidate for potential biomarkers of diseases in which the current knowledge of the cause and treatment is limited. The developed ISFET was based on the outstanding electrical characteristics of the metal–oxide–semiconductor field-effect transistor (MOSFET) with a subthreshold swing of 85 mV/dec, low leakage current of -12 and high on/off current ratio of 7.3×106. The SiO2 sensing membrane with a pH sensitivity of 34.9 mV/pH and drift rate 1.17 mV/h was sufficient for biosensing applications. In addition, the sensor device also showed significant compatibility with the Drosophila cells expressing Gr5a and their response to sugar, particularly trehalose. Moreover, the interactions between the transfected Drosophila cells and trehalose were consistent and reliable. This suggests that the developed ISFET sensor device could have potential use in the future as a screening device in diagnosis.