Enzyme Method-Based Microfluidic Chip for the Rapid Detection of Copper Ions

Metal ions in high concentrations can pollute the marine environment. Human activities and industrial pollution are the causes of Cu2+ contamination. Here, we report our discovery of an enzyme method-based microfluidic that can be used to rapidly detect Cu2+ in seawater. In this method, Cu2+ is reduced to Cu+ to inhibit horseradish peroxidase (HRP) activity, which then results in the color distortion of the reaction solution. The chip provides both naked eye and spectrophotometer modalities. Cu2+ concentrations have an ideal linear relationship, with absorbance values ranging from 3.91 nM to 256 μM. The proposed enzyme method-based microfluidic chip detects Cu2+ with a limit of detection (LOD) of 0.87 nM. Other common metal ions do not affect the operation of the chip. The successful detection of Cu2+ was achieved using three real seawater samples, verifying the ability of the chip in practical applications. Furthermore, the chip realizes the functions of two AND gates in series and has potential practical implementations in biochemical detection and biological computing.

Synthesis of Ag–Cu alloy nanosheets for ascorbic acid detection

Metal alloy nanosheets play a very important role as catalysts, which also show obvious advantages in the field of biosensor. Compared with traditional methods, such as enzyme method, gas chromatography or optical absorbance, the detection of ascorbic acid is simpler and more stable by spectroscopy. Ag–Cu alloy nanosheets with a thickness of about 1–3 nm and an average lateral size of 3–5 nm were synthesized in this study by the soft template method. These nanosheets were used to construct a sensor for measuring the concentration of ascorbic acid. The initial UV-Vis absorption peaks for the Ag–Cu alloy nanosheets in aqueous solution were effectively quenched upon addition of ascorbic acid. As the ascorbic acid concentration was in the range of 5–250 mmol/L changes, the UV absorbance intensity for the sensor also changed. Because of its wide detection range, high sensitivity, and excellent stability, the Ag–Cu alloy sensor method may be an excellent alternative to the traditional ascorbic acid measure method.

CARDIOVASCULAR SYSTEM OF THE MATURE RATS WITH CONGENITAL HYPOTHYROIDISM AND ARTERIAL HYPERTENSION

The aim: Studying changes in the ultrastructure of blood circulatory capillaries of the myocardium of mature rats with hypothyroidism and arterial hypertension. Materials and methods: Experiments were conducted on (240 days) 10 ISIAH (inherited stress-induced arterial hypertension) line rats with AH (arterial hypertension), 10 Wistar line rats with congenital hypothyroidism and 10 intact animals. Arterial pressure was measured, and the development of hypothyroidism was controlled by the immune enzyme method. The study of the left ventricle myocardium of the rat heart was carried out by electron microscopic and morphometric studies. Results: In in rats with AH the following changes were observed in the blood capillaries of the myocardium: decrease in the number of capillaries; disturbance of blood circulation; the number of organelles of the biosynthetic plan and structures involved in the transendothelial transfer of substances decreased in endothelial cells; lysis and edema of the latter; mucinous perivascular edema, confirmed by the accumulation of fine-fibrillar structures, collagen fibers, cellular detritus. By the same term, in the group with congenital hypothyroidism, dystrophic-destructive changes in the blood capillaries of the myocardium acquired the highest degree, which resulted in a decrease in their number due to destruction. Ultrastructure of the biosynthetic plan organelles and structures of the transendothelial transfer of substances were in decompensated state. Conclusions: The rats (in 240 days) with AH and congenital hypothyroidism express breakdown of compensatory processes in the capillaries of the myocardium. This is manifested by the further dilution of capillaries, the development of hypoxic state in them as well as mucinous edema of interstitium, the decrease of activity of biosynthetic and transport processes.

EFFECT OF CYTOMEGALOVIRUS INFECTION ON PROGESTERONE CONVERSION INTO A METABOLITE 5α-PREGNAN-3.20-DIONE IN THE PLACENTA IN EARLY PREGNANCY

The aim was to study the activity of progesterone and 5α-pregnan-3.20-dione conversion in the placenta at the exacerbation of cytomegalovirus infection (CMVI) during the first trimester of pregnancy. The study material included 50 villous chorions taken during medical abortions in the period of 8-10 weeks from women with exacerbation of chronic CMVI during pregnancy. The control group had 35 villous chorions of pregnant women of the same gestation period with chronic CMVI in the latent stage. Diagnosis of CMVI was performed taking into account the activity of CMVI with the immune-enzyme method by the level of antibodies of IgM and antibody titers of IgG in the paired serums in dynamics in 10 days. The progesterone content was determined at the “Stat Fax-2100ˮ spectrophotometer. The activity of 4-pregnene-3.20-dione dehydrogenase and 5α-pregnane-3.20-dione dehydrogenase was assessed by the histochemical method. Quantitative evaluation of the reaction products was carried out on sections under the microscope “Meiji Technoˮ connected to the software-hardware complex “SCION Corporationˮ. It was found out that progesterone content in villous chorions of women with reactivation of CMVI during pregnancy was reduced to 21.5±2.73 nmol/L in comparison with the control group (53.4±3.70 nmol/L, p<0.001). The disturbance of progesterone inversion intensiveness in placenta was proved by the decrease of enzyme activity: of 4-pregnene-3.20-dione dehydrogenase till 15.9±0.47 standard units (in control it was 28.6±0.58 standard units, p<0.001) and of 5α-pregnan-3.20-dione till 16.2±1.11 standard units (in control it was 25.0±1.91 standard units, p<0.001). Reduction in the intensity of progesterone conversion into 5α-dihydroprogesterone (5α-pregnan-3.20-dione) in the placenta with the exacerbation of CMVI can negatively affect the formation and functioning of the fetal nervous system.

Količina šećera u mesnim proizvodima s hrvatskog tržišta

Content of sugar in meat products from the Croatian market Sugars are used in the production of meat products to produce lactic acid and to achieve specific sensory properties, thus ensuring the quality and stability of the final product. The aim of this paper was to determine the differences in sucrose, glucose and fructose sugar levels in meat products from different categories available on the Croatian market. A total of 140 samples were analyzed from the category of fermented (n = 41) and heat treated (n = 82) sausages and dry cured meat products (n = 17). For the determination of the sugar level, a validated enzyme method was used. Within each of the three investigated categories the highest sucrose content (0.21-0.87%) was determined, followed by fructose (0.10-0.39%) and the lowest glucose (0.05-0.06%). The total sugar content, as a sum of sucrose, fructose and glucose, was 1.32% in the category of heat treated sausages, 0.36% in fermented sausages and 0.47% in dry cured meat products. The results of the research indicate the variation in the quantity of added sugar in meat products from the Croatian market, with total shares ranging from 1 to 2%, depending on the type of product and the producer's recipe, according to the literature of other authors for the same category of meat products.