Near-Infrared Light Emitting Diode Based Non-Invasive Glucose Detection System.

Diabetes mellitus is a common disease that has affected people since antiquity. The complexity of diabetes mellitus lies in the fact that it requires continuous management in order to prevent serious complications. Various methods for managing diabetes mellitus through monitoring blood glucose levels have been studied and developed, and the most widely used method includes using an invasive blood glucose meter. Since the invasive blood glucose meter poses a major inconvenience for patients, in this study, we sought to develop a non-invasive blood glucose meter. We therefore proposed the development of a non-invasive blood glucose measurement system that is based on near-infrared spectroscopy. The system developed was composed of a light source for emitting different wavelengths, a light detector unit, and a computing system for recording signals. A prepared glucose solution was injected into a quartz cuvette and light at 780-1650 nm was emitted to pass through the cuvette. The degree of reaction was determined by recording the change in wavelength. The wavelength band used for the experiment was 780-1000 nm and the resolution was 20 nm. The glucose concentration was determined to be between 50 to 400 mg/dl compared to the normal range of 80 to 120 mg/dl. By examining which wavelength bands specifically reacted with glucose, we observed that the wavelength bands that decreased or increased in response to the glucose concentration were at 780 nm and 940 nm. For wavelength bands at 1000 nm or above, light was also absorbed by water and therefore it was difficult to distinguish the results. The most reliable wavelength band was at 940 nm with an R² of 0.9806. In conclusion, the near-infrared light emitting diode based non-invasive glucose detection system performed well and is expected to be a superior method for monitoring blood glucose levels in diabetes mellitus.

Anti-Inflammatory Effects of Step Electrical Stimulation on Complete Freund's Adjuvant (CFA) Induced Rheumatoid Arthritis Rats.

Rheumatoid arthritis is a chronic inflammatory disease that affects joints and induces pain and swelling. We evaluated the anti-inflammatory effects of step electrical stimulation (SES) in this study. SES was carried out by increasing the voltage (3 V/s) from 5 V to 100 V for 60 cycles. The viability of mouse embryonic fibroblasts (NIH-3T3) was evaluated after step-electrical stimulation. After the injection of complete Freund's adjuvant (CFA) on the right hind paw of Sprague Dawley (SD) rats (6 weeks old), the degree of swelling was measured using a digital plethysmometer and Vernier caliper. Histological changes in inflamed tissues were observed with hematoxylin and eosin (H&E) staining, while the degree of inflammation was evaluated from the expression level of inflammatory factors such as cyclooxygenase-2 (COX-2), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6). As a result, we found no difference in cell viability after SES treatment between the control and SES-treated groups. On day 21 after CFA injection, the swelling of right hind paws decreased by 1.09 times in SES-treated group as compared with the untreated group. In addition, the levels of COX-2, TNF-α and IL-6 significantly decreased after SES treatment. Thus, SES treatment decreased paw swelling and alleviated inflammation.

Local-dependency of morphological and optical properties between breast cancer cell lines.

Breast cancer is the most malignant type of cancer in women and is a global health problem, with mortality by metastasis being the main factor among others. Currently, detection and diagnosis of breast cancer is achieved through a variety of procedures, such as clinical examination, medical imaging, biopsy, and histopathological analysis. In contrast, spectroscopic analysis has a variety of advantages such as being noninvasive, not destroying biological materials, and not requiring additional histological analysis. In this study, various approaches using Raman spectroscopy, atomic force microscopy (AFM), and optical microscopy were used together to differentiate between and characterize normal breast cell lines (MCF-10A) and breast cancer cell lines (MDA-MB-231, MDA-MB-453). Raman spectra of normal breast cell and breast cancer cell lines confirmed visual differences in the concentrations of various compounds. These spectra were also analyzed using principle component analysis (PCA), and the PCA results showed reliable separation of the three cell lines and the cancer cell lines (MDA-MB-231, MDA-MB-453). With these results, optically synchronizing the AFM morphology, the Raman spectroscopy, and the visible RGB optical transmission intensity provided contrasts for not only conformational differences but also intracellular variation between the normal and cancer cell lines. We observed the inherent characteristic that there is no local difference in cancer cells regardless of morphology in a wide range of optical properties such as absorption, scattering and inelastic scattering.

Cell viability, adhesion and function of RAW 264.7 macrophages on fluorinated xerogel-derived nitric oxide permeable membrane for the application of cellular sensing.

Organically modified xerogels have an advantage over gas sensing applications due to their open, rigid structure and hydrophobicity. Here we evaluated the biocompatibility of xerogel-derived nitric oxide (NO) permeable membranes modified with fluorinated functional groups for application in cellular sensing by growing RAW 264.7 macrophages on them. We examined the cell viability, adhesion and growth of RAW 264.7 macrophages on NO permselective membrane and other cell-adhesive matrices, poly L-lysine and collagen. The surface roughness of each membrane was obtained from topographic atomic force microscopy (AFM) images. In addition, we measured the level of NO release of RAW 264.7 macrophages by lipopolysaccharide (LPS) stimulation using a Griess assay to confirm the function of cells. The fluorinated xerogel-derived membrane had a very smooth surface with rms roughness 2.1 Å and did not show cytotoxic effects in RAW 264.7 macrophages. As a result, the morphology and function of adhering RAW 264.7 macrophage showed no differences from those of other cell-adhesive membranes. Finally, we successfully detected NO release in RAW 264.7 macrophages stimulated by LPS, using a planar-type xerogel-derived NO sensor. Therefore, we suggest that fluorinated xerogel-derived membrane could be used as both a NO permeable and cell-adhesive membrane for cellular sensing applications.

Simultaneous, real-time measurement of nitric oxide and oxygen dynamics during cardiac ischemia-reperfusion of the rat utilizing sol-gel-derived electrochemical microsensors.

In this study, we simultaneously measured nitric oxide (NO) and oxygen (O2) dynamics in the myocardium during myocardial ischemia-reperfusion (IR) utilizing sol-gel modified electrochemical NO and O2 microsensors. In addition, we attempted to clarify the correlation between NO release in the ischemic period and O2 restoration in the myocardium after reperfusion, comparing a control heart with a remote ischemic preconditioning (RIPC)-treated heart as an attractive strategy for myocardial protection. Rat hearts were randomly divided into two groups: a control group (n=5) and an RIPC group (n=5, with RIPC treatment). Myocardia that underwent RIPC treatment (182±70 nM, p<0.05) released more NO during the ischemic period than those of the control group (63±41 nM). The restoration value of oxygen tension (pO2) in the RIPC group significantly increased and was restored to pre-ischemic levels (92.6±36.8%); however, the pO2 of the control group did not increase throughout the reperfusion period (5.7±7.5%, p=0.001). Myocardial infarct size measurements revealed a significant decrease in cell death in the myocardium region of the RIPC group (41.44±6.42%, p=0.001) compared with the control group (60.05±10.91%). As a result, we showed that the cardioprotective effect of RIPC could be attributed to endogenous NO production during the ischemic period, which subsequently promoted reoxygenation in post-ischemic myocardia during early reperfusion. Our results suggest that the promotion of endogenous formation during an ischemic episode might be helpful as a therapeutic strategy for protecting the myocardium from IR injury. Additionally, our NO and O2 perm-selective microsensors could be utilized to evaluate the effect of drug or treatment.

Real time measurement of myocardial oxygen dynamics during cardiac ischemia-reperfusion of rats.

Because oxygen plays a critical role in the pathophysiology of myocardial injury during subsequent reperfusion, as well as ischemia, the accurate measurement of myocardial oxygen tension is crucial for the assessment of myocardial viability by ischemia-reperfusion (IR) injury. Therefore, we utilized a sol-gel derived electrochemical oxygen microsensor to monitor changes in oxygen tension during myocardial ischemia-reperfusion. We also analyzed differences in oxygen tension recovery in post-ischemic myocardium depending on ischemic time to investigate the correlation between recovery parameters for oxygen tension and the severity of IR injury. An oxygen sensor was built using a xerogel-modified platinum microsensor and a coiled Ag/AgCl reference electrode. Rat hearts were randomly divided into 5 groups: control (0 min ischemia), I-10 (10 min ischemia), I-20 (20 min ischemia), I-30 (30 min ischemia), and I-40 (40 min ischemia) groups (n = 3 per group, respectively). After the induction of ischemia, reperfusion was performed for 60 min. As soon as the ischemia was initiated, oxygen tension rapidly declined to near zero levels. When reperfusion was initiated, the changes in oxygen tension depended on ischemic time. The normalized peak level of oxygen tension during the reperfusion episode was 188 ± 27 in group I-10, 120 ± 24 in group I-20, 12.5 ± 10.6 in group I-30, and 1.24 ± 1.09 in group I-40 (p < 0.001, n = 3, respectively). After 60 min of reperfusion, the normalized restoration level was 129 ± 30 in group I-10, 88 ± 4 in group I-20, 3.40 ± 4.82 in group I-30, and 0.99 ± 0.94 in group I-40 (p < 0.001, n = 3, respectively). The maximum and restoration values of oxygen tension in groups I-30 and I-40 after reperfusion were lower than pre-ischemic values. In particular, oxygen tension in the I-40 group was not recovered at all. These results were also demonstrated by TTC staining. We suggest that these recovery parameters could be utilized as an index of tissue injury and severity of ischemia. Therefore, quantitative measurements of oxygen tension dynamics in the myocardium would be helpful for evaluation of the cardioprotective effects of therapeutic treatments such as drug administration.