Bioconjugation of peptides using advanced nanomaterials to examine their interactions in 3D printed flow-through device.

Peptide-peptide interactions are crucial in the living cell as they lead to the formation of the numerous types of complexes. In this study, synthetic peptides containing 11 of cysteines (α-domain of metallothionein (MT)) and sialic acid binding region (130-loop of hemagglutinin (HA)) were employed. The aim of the experiment was studying the interactions between MT and HA-derived peptides. For this purpose, fragments were tagged with cysteines at C-terminal part to serve as ligand sites for PbS and CuS quantum dots (QDs), and therefore these conjugates can be traced and quantified during wide spectrum of methods. As a platform for interaction, γ-Fe2O3 paramagnetic particles modified with tetraethyl orthosilicate and (3-aminopropyl)triethoxysilane (hydrodynamic diameter 30-40 nm) were utilized and MT/HA interactions were examined using multi-instrumental approach including electrochemistry, electrophoretic methods, and MALDI-TOF/TOF mass spectrometry. It was found that peptides enter mutual creation of complexes, which are based on some of nonbonded interactions. The higher willingness to interact was observed in MT-derived peptides toward immobilized HA. Finally, we designed and manufactured flow-through electrochemical 3D printed device (reservoir volume 150 µL) and utilized it for automated analysis of the HA/MT metal labels. Under the optimal conditions, (deposition time and flow rate 80 s and 1.6 mL/min for CuS and 120 s and 1.6 mL/min PbS, respectively), the results of peptide-conjugated QDs were comparable with atomic absorption spectrometry.

Distribution of mercury in rainbow trout tissues at embryo-larval and juvenile stages.

The aims of the study were to determine total mercury concentrations in "rainbow trout Oncorhynchus mykiss (Walbaum)" at their embryo-larval and juvenile stages and to assess mercury concentration dynamics in individual tissues. Samples of rainbow trout were collected at two-month intervals over a period of 18 months (one stock production cycle) at the Velká Losenice trout farm. Feedstuff samples were collected at the same time and analyzed for mercury concentrations. Tissue mercury concentrations were determined in muscle, liver, and kidneys. Analyses were performed using the AMA 254 atomic absorption spectrophotometer. The lowest mercury concentration was found in 14-day-old embryos (hard roe), and the highest concentrations in muscle tissue, liver, and kidneys at the end of monitoring, that is, in rainbow trout aged 18 months. The amount of mercury in feedstuffs showed an increasing trend and ranged between 0.0126 and 0.0859 mg kg(-1). A significant effect (P < 0.001) of mercury intake on mercury concentrations in muscle tissue, liver, and kidneys was demonstrated. Muscle mercury concentrations in 18-month-old market-ready rainbow trout of 0.128 ± 0.048 mg kg(-1) met the criteria for fish meat hygiene.

Using human hair as an indicator for exposure to mercury.

OBJECTIVES: Exposure to mercury, a risk factor for neuro-developmental toxicity, was evaluated in the Czech Republic by performing mercury determination using human hair as an indicator. METHODS: Hair samples from Czechs (n=311; 2-66 years old) were analyzed for mercury content. Total mercury was analysed by mercury analyzer AMA 254. RESULTS: The highest total mercury content found in sampled hair was 3.55 microg/g and the lowest content was 0.015 microg/g. No correlation was found between the mercury levels in the sampled hair and the subject's age, gender, and the amount of amalgam fillings. A total of 38 hair samples were analyzed for methylmercury content. CONCLUSION: The results show a positive correlation between the total mercury content in human hair and the consumption of marine and freshwater fish. Hair are a very good indicator of fish consumption.

Mercury in human hair as an indicator of the fish consumption.

OBJECTIVES: Mercury and most of its compounds are extremely toxic and should be handled with care. It can be inhaled and absorbed through the skin and mucous membranes. The most toxic forms of mercury are its organic compounds such as dimethylmercury and methylmercury. Fish have a natural tendency to accumulate mercury. Methylmercury is produced by microbial methylation of inorganic mercury in water sediment then it infiltrates the food chain and it consequently accumulates in fish. Fish are the main source of methylmercury in human food. Mercury is transferred into a hair; and this can be than used to monitor the long-term exposure to mercury. The content of mercury in hair depends on the frequency of fish consumption. The aim of our study was to compare mercury content in the hair of children that had various amounts of fish consumption (increased or reduced). DESIGN: Total mercury content in hair was determined by direct method of cold vapors using an AMA 245 analyzer. A total of 174 hair samples from the children (9-17 years old) were analyzed. In this study, the following localities were compared: Neratovice (n=42), Jeseníky (n=44), Prague (n=59) in Czech Republic and Olsztyn in Poland (n=29). Every sample was accompanied with questionnaire about age, gender, regions, amalgam fillings and fish consumption. RESULTS: We did not find a correlation between the content of mercury in hair with age, gender or amalgam fillings. We did find a correlation between fish consumption and the amount of mercury found in the hair samples. CONCLUSION: The amount of mercury in hair increases with more frequent consumption of freshwater and marine fish.

Use of nucleic acids anchor system to reveal apoferritin modification by cadmium telluride nanoparticles.

The aim of this study was to synthesize cadmium telluride nanoparticles (CdTe NPs) modified apoferritin, and examine if apoferritin is able to accommodate CdTe NPs. Primarily, the thermostability of horse spleen apoferritin was tested and it's unfolding at 70 °C was observed. Cadmium telluride nanoparticles (CdTe NPs) were synthesized both within apoferritin protein cage and on its surface. The thermal treatment of apoferritin with CdTe NPs resulted in the aggregation of cores, which was indicated by changes in the absorption spectra and the shape of apoferritin tryptophan fluorescence. The apoferritin modified with CdTe NPs was additionally modified with gold nanoparticles and attached to magnetic particles via oligonucleotide using gold affinity to thiol group. This anchor system was used to separate the construct using external magnetic field and to analyse the molecules attached to apoferritin.

Interaction study of arsenic (III and V) ions with metallothionein gene (MT2A) fragment.

Arsenic compounds belong to the most controversial agents concerning human health. Arsenic (As) is considered as a top environmental element influencing human health due to its adverse effects including cancer, diabetes, cardiovascular disease, and reproductive or developmental problems. Despite the proven mutagenic, teratogenic and carcinogenic effects, the arsenic compounds are used for centuries to treat infectious diseases. In our work, we focused on studying of interactions of As(III) and/or As(V) with DNA. Interactions between arsenic ions and DNA were monitored by UV/vis spectrophotometry by measuring absorption and fluorescence spectra, atomic absorption spectrometry, electrochemical measurements (square wave voltammetry) and agarose gel electrophoresis. Using these methods, we observed a stable structure of DNA with As(III) within the concentration range 0.4-6.25 µg mL(-1). Higher As(III) concentration caused degradation of DNA. However, similar effects were not observed for As(V).

Lead ions encapsulated in liposomes and their effect on Staphylococcus aureus.

The aim of the study was the preparation of a liposome complex with encapsulated lead ions, which were electrochemically detected. In particular, experiments were focused on the potential of using an electrochemical method for the determination of free and liposome-encapsulated lead and determination of the encapsulation efficiency preventing the lead toxicity. Primarily, encapsulation of lead ions in liposomes and confirmation of successful encapsulation by electrochemical methods was done. Further, the reduction effect of the liposome matrix on the detected electrochemical signal was monitored. Besides encapsulation itself, comparison of toxicity of free lead ions and lead ions encapsulated in liposome was tested. The calculated IC50 values for evaluating the lead cytotoxicity showed significant differences between the lead enclosed in liposomes (28 µM) and free lead ions (237 µM). From the cytotoxicity studies on the bacterial strain of S. aureus it was observed that the free lead ions are less toxic in comparison with lead encapsulated in liposomes. Liposomes appear to be a suitable carrier of various substances through the inner cavity. Due to the liposome structure the lead enclosed in the liposome is more easily accepted into the cell structure and the toxicity of the enclosed lead is higher in comparison to free lead ions.