Heparin mimetic peptide nanofiber gel promotes regeneration of full thickness burn injury.

Burn injuries are one of the most common types of trauma worldwide, and their unique physiology requires the development of specialized therapeutic materials for their treatment. Here, we report the use of synthetic, functional and biodegradable peptide nanofiber gels for the improved healing of burn wounds to alleviate the progressive loss of tissue function at the post-burn wound site. These bioactive nanofiber gels form scaffolds that recapitulate the structure and function of the native extracellular matrix through signaling peptide epitopes, which can trigger angiogenesis through their affinity to basic growth factors. In this study, the angiogenesis-promoting properties of the bioactive scaffolds were utilized for the treatment of a thermal burn model. Following the excision of necrotic tissue, bioactive gels and control solutions were applied topically onto the wound area. The wound healing process was evaluated at 7, 14 and 21 days following injury through histological observations, immunostaining and marker RNA/protein analysis. Bioactive peptide nanofiber-treated burn wounds formed well-organized and collagen-rich granulation tissue layers, produced a greater density of newly formed blood vessels, and exhibited increased re-epithelialization and skin appendage development with minimal crust formation, while non-bioactive peptide nanofibers and the commercial wound dressing 3M™ Tegaderm™ did not exhibit significant efficiency over sucrose controls. Overall, the heparin-mimetic peptide nanofiber gels increased the rate of repair of burn injuries and can be used as an effective means of facilitating wound healing.

Phytoremediation of Cu, Cr and Pb mixtures by Lemna minor.

The present study reports the capacity of the aquatic macrophyte Lemna minor to remediate combinations of Cu(II), Pb(II) and Cr(III) from a simulated natural environment. The effect of these metal mixtures on the growth of L. minor was also investigated using growth rate and biomass inhibition calculations. L. minor was successful in removing Cr and Pb from the water, and it remained an effective remediation agent when both metals were present in the environment. However, a relatively low absorption capacity was observed for Cu, increasing concentrations of which were associated with significant decreases in growth rate. No statistically significant difference was found between the 24 h and 7 days absorption rates of Cu, Pb and Cr, suggesting that, at the concentrations tested, equilibrium occurs within 24 h of metal exposure.

Label-free nanometer-resolution imaging of biological architectures through surface enhanced Raman scattering.

Label free imaging of the chemical environment of biological specimens would readily bridge the supramolecular and the cellular scales, if a chemical fingerprint technique such as Raman scattering can be coupled with super resolution imaging. We demonstrate the possibility of label-free super-resolution Raman imaging, by applying stochastic reconstruction to temporal fluctuations of the surface enhanced Raman scattering (SERS) signal which originate from biomolecular layers on large-area plasmonic surfaces with a high and uniform hot-spot density (>10¹¹/cm², 20 to 35 nm spacing). A resolution of 20 nm is demonstrated in reconstructed images of self-assembled peptide network and fibrilated lamellipodia of cardiomyocytes. Blink rate density is observed to be proportional to the excitation intensity and at high excitation densities (>10 kW/cm²) blinking is accompanied by molecular breakdown. However, at low powers, simultaneous Raman measurements show that SERS can provide sufficient blink rates required for image reconstruction without completely damaging the chemical structure.

Fourier transform infrared spectroscopy as a novel approach for analyzing the biochemical effects of anionic surfactants on a surfactant-degrading Arcobacter butzleri strain.

Anionic surfactant-biodegrading capability of an Arcobacter butzleri strain was analyzed under aerobic conditions. The A. butzleri isolate displayed efficient surfactant-biodegrading capacity for sodium dodecyl sulfate (SDS) at concentrations of up to 100 mg/L in 6 days, corresponding to 99.0% removal efficiency. Fourier transform infrared spectroscopy was applied to observe the effects of varying concentrations of SDS on the biochemistry of bacterial cells. Results suggest that protein secondary structures were altered in bacterial cells at sufficiently high SDS concentrations, concurrent with SDS biodegradation.

Differences in the accumulation and distribution profile of heavy metals and metalloid between male and female crayfish (Astacus leptodactylus).

Concentrations of selected heavy metals and a metalloid were measured by ICP-MS in crayfish (Astacus leptodactylus) collected from Lake Hirfanli, Turkey. Aluminum (Al), chromium ((52)Cr, (53)Cr), copper ((63)Cu, (65)Cu), manganese (Mn), nickel (Ni) and arsenic (As) were measured in the exoskeleton, gills, hepatopancreas and abdominal muscle tissues of 60 crayfish of both genders. With the exception of Al, differences were determined between male and female cohorts for the accumulation trends of the above-mentioned elements in the four tissues. It was also noted that the accumulation rates of Ni and As were significantly lower in gill tissue of females compared to males and no significant difference was observed for Cu isotopes in female crayfish. Cluster Analysis (CA) recovered similar results for both genders, with links between accumulations of Ni and As being notable. Accumulation models were described separately for male and female crayfish using regression analysis, and are presented for models where R(2) > 0.85.

Tissue distribution and correlation profiles of heavy-metal accumulation in the freshwater crayfish Astacus leptodactylus.

The present work details the analysis of heavy-metal and metalloid concentrations in exoskeleton, gill, hepatopancreas, and abdominal muscle tissues of 60 crayfish (Astacus leptodactylus) specimens collected from Lake Hirfanli, a dam lake located in Kirsehir (Turkey) with a low metal-contamination profile. Concentrations of 11 metals (aluminum [Al], chromium [Cd], manganese [Mn], cobalt [Co], nickel [Ni], copper [Cu], molybdenum [Mo], silver [Ag], cadmium [Cd], mercury [Hg], and lead [Pb]) and a metalloid (arsenic [As]) were measured by inductively coupled plasma-mass spectrometry, and the relative frequencies of the most abundant isotopes of Cr, Cu, Ag, Cd, Hg, and Pb were evaluated. Three correlation trends were evaluated between the following: (1) different elements in the each individual tissue, (2) individual elements in different tissues, and (3) different elements in different tissues. In addition, correlation rates of growth parameters (weight, cephalothorax length, and total length) with heavy-metal and metalloid concentrations in each tissue were investigated. Our results suggest that substantial differences in metal and metalloid-accumulation levels exist between male and female specimens, with stronger correlations between the heavy-metal concentrations observed in the male cohort. It is notable that correlation trends of Co, Cu, (52)As, Cr, and Ni in exoskeleton of the male specimens display strong similarities. Likewise, a very strong correlation is present in Ni-Cd and Ni-Pb accumulations in abdominal muscle of the male specimens; a similar trend is present between Cd and Pb concentrations in the same tissue of female specimens. For correlation rates of different heavy metals and metalloid in different tissues, the strongest positive association observed was between (63)Cu in gill and As in hepatopancreas, whereas the strongest negative correlation was between accumulated Ni in abdominal muscle and As in exoskeleton. Strong correlations between metals and metalloid accumulations were observed between exoskeleton and gill. In many cases, metal and metalloid accumulation was negatively correlated with growth parameters. Preferential accumulation of Cr and Cu isotopes was observed in different tissues, suggesting that significant amounts of isotope fractionation occur during heavy-metal accumulation. Relatively low correlation rates were observed between (52)Cr/(53)Cr and (63)Cu/(65)Cu concentrations in several tissue types in both male and female cohorts, whereas no such trend was observed between Cd and Pb isotopes.

Differential effects of nitrogen and sulfur deprivation on growth and biodiesel feedstock production of Chlamydomonas reinhardtii.

Biodiesel production from microalgae is a promising approach for energy production; however, high cost of its process limits the use of microalgal biodiesel. Increasing the levels of triacylglycerol (TAG) levels, which is used as a biodiesel feedstock, in microalgae has been achieved mainly by nitrogen starvation. In this study, we compared effects of sulfur (S) and nitrogen (N) starvation on TAG accumulation and related parameters in wild-type Chlamydomonas reinhardtii CC-124 mt(-) and CC-125 mt(+) strains. Cell division was interrupted, protein and chlorophyll levels rapidly declined while cell volume, total neutral lipid, carotenoid, and carbohydrate content increased in response to nutrient starvation. Cytosolic lipid droplets in microalgae under nutrient starvation were monitored by three-dimensional confocal laser imaging of live cells. Infrared spectroscopy results showed that relative TAG, oligosaccharide and polysaccharide levels increased rapidly in response to nutrient starvation, especially S starvation. Both strains exhibited similar levels of regulation responses under mineral deficiency, however, the degree of their responses were significantly different, which emphasizes the importance of mating type on the physiological response of algae. Neutral lipid, TAG, and carbohydrate levels reached their peak values following 4 days of N or S starvation. Therefore, 4 days of N or S starvation provides an excellent way of increasing TAG content. Although increase in these parameters was followed by a subsequent decline in N-starved strains after 4 days, this decline was not observed in S-starved ones, which shows that S starvation is a better way of increasing TAG production of C. reinhardtii than N starvation.