The induction of α-helical structure in partially unfolded HypF-N does not affect its aggregation propensity

The conversion of proteins into structured fibrillar aggregates is a central problem in protein chemistry, biotechnology, biology and medicine. It is generally accepted that aggregation takes place from partially structured states of proteins. However, the role of the residual structure present in such conformational states is not yet understood. In particular, it is not yet clear as to whether the α-helical structure represents a productive or counteracting structural element for protein aggregation. We have addressed this issue by studying the aggregation of pH-unfolded HypF-N. It has previously been shown that the two native α-helices of HypF-N retain a partial α-helical structure in the pH-unfolded state and that these regions are also involved in the formation of the cross-β structure of the aggregates. We have introduced mutations in such stretches of the sequence, with the aim of increasing the α-helical structure in the key regions of the pH-unfolded state, while minimizing the changes of other factors known to influence protein aggregation, such as hydrophobicity, β-Sheet propensity, etc. The resulting HypF-N mutants have higher contents of α-helical structure at the site(s) of mutation in their pH-unfolded states, but such an increase does not correlate with a change of aggregation rate. The results suggest that stabilisation of α-helical structure in amyloidogenic regions of the sequence of highly dynamic states does not have remarkable effects on the rate of protein aggregation from such conformational states. Comparison with other protein systems indicate that the effect of increasing α-helical propensity can vary if the stabilised helices are in non-amyloidogenic stretches of initially unstructured peptides (accelerating effect), in amyloidogenic stretches of initially unstructured peptides (no effect) or in amyloidogenic stretches of initially stable helices (decelerating effect

Photobiomodulation of human fibroblasts and keratinocytes with blue light: Implications in wound healing

In recent years, photobiomodulation (PBM) has been recognized as a physical therapy in wound management. Despite several published research papers, the mechanism underlying photobiomodulation is still not completely understood. The investigation about application of blue light to improve wound healing is a relatively new research area. Tests in selected patients evidenced a stimulation of the healing process in superficial and chronic wounds treated with a blue LED light emitting at 420 nm; a study in animal model pointed out a faster healing process in superficial wound, with an important role of fibroblasts and myofibroblasts. Here, we present a study aiming at evidencing the effects of blue light on the proliferation and metabolism in fibroblasts from healthy skin and keratinocytes. Different light doses (3.43, 6.87, 13.7, 20.6, 30.9 and 41.2 J/cm2) were used to treat the cells, evidencing inhibitory and stimulatory effects following a biphasic dose behavior. Electrophysiology was used to investigate the effects on membrane currents: healthy fibroblasts and keratinocytes showed no significant differences between treated and not treated cells. Raman spectroscopy revealed the mitochondrial Cytochrome C (Cyt C) oxidase dependence on blue light irradiation: a significant decrease in peak intensity of healthy fibroblast was evidenced, while it is less pronounced in keratinocytes. In conclusion, we observed that the blue LED light can be used to modulate metabolism and proliferation of human fibroblasts, and the effects in wound healing are particularly evident when studying the fibroblasts and keratinocytes co-cultures

Ready-to-use protein G-conjugated gold nanorods for biosensing and biomedical applications

Abstract Background Gold nanorods (GNRs) display unique capacity to absorb and scatter near infrared light, which arises from their peculiar composition of surface plasmon resonances. For this reason, GNRs have become an innovative material of great hope in nanomedicine, in particular for imaging and therapy of cancer, as well as in photonic sensing of biological agents and toxic compounds for e.g. biomedical diagnostics, forensic analysis and environmental monitoring. As the use of GNRs is becoming more and more popular, in all these contexts, there is emerging a latent need for simple and versatile protocols for their modification with targeting units that may convey high specificity for any analyte of interest of an end-user. Results We introduce protein G-coated GNRs as a versatile solution for the oriented immobilization of antibodies in a single step of mixing. We assess this strategy against more standard covalent binding of antibodies, in terms of biocompatibility and efficiency of molecular recognition in buffer, serum and plasma, in the context of the development of a direct immunoenzymatic assay. In both cases, we estimate an average of around 30 events of molecular recognition per particle. In addition, we disclose a convenient protocol to store these particles for months in a freezer, without any detrimental effect. Conclusions The biocompatibility and efficiency of molecular recognition is similar in either case of GNRs that are modified with antibodies by covalent binding or oriented immobilization through protein G. However, protein G-coated GNRs are most attractive for an end-user, owing to their unique versatility and ease of bioconjugation with antibodies of her/his choice

Electro-Responsive Green Gels for Lower Environmental Impact Shale Gas Extraction

In this work, carbon black (CB) is added in small amounts (3–10% w/w) to green aqueous dispersions based on sodium oleate, guar gum, sodium hyaluronate, or hydroxypropyl cellulose gels to enhance their stability against mechanical and thermal stresses and to provide electric responsiveness to an external voltage. Rheology, optical microscopy, small angle X-ray scattering, and conductivity measurements are performed to compare the properties of CB-enriched formulations to those of pristine dispersions. Our results demonstrate that even small amounts of CB are able to confer interesting physicochemical properties to these formulations: a remarkable increase in the viscosity of at least 1 order of magnitude is observed for all systems even at high temperature (up to 60 °C) upon CB addition, indicating that carbonaceous particles play a structuring role for the polymeric network. Furthermore, the application of an external voltage of 30 V for 60 min to CB-containing formulations imparts a significant electric responsiveness to the systems, allowing the modification of their rheological behavior. The CB-loaded formulations can be recycled at least three times. All these results suggest that CB can be effectively used as an alternative green additive to enhance the mechanical and thermal stabilities of the formulations and that its addition can be a feasible way to easily tune the properties of viscoelastic materials, thereby avoiding the use of toxic or potentially dangerous chemicals. The possibility of achieving remote control of mechanical and thermal properties of viscoelastic formulations significantly expands the horizon of their potential applications, for example, in the field of shale gas extraction

Specific ion effects in polysaccharide dispersions

The specific effects induced by some strong electrolytes or neutral co-solutes on aqueous mixtures of guar gum (GG), sodium alginate (SA) and sodium hyaluronate (SH) were studied through rheology and DSC experiments. The results are discussed in terms of changes in the polymer conformation, structure of the network and hydration properties. This study is also aimed at controlling the viscosity of the aqueous mixtures for application in green formulations to be used as fracturing fluids for shale gas extraction plants. (C) 2017 Elsevier Ltd. All rights reserved

MOESM1 of Ready-to-use protein G-conjugated gold nanorods for biosensing and biomedical applications

Additional file 1. Additional details on the PEGylation of the gold nanorods

Physicochemical characterization of green sodium oleate-based formulations. Part 3. Molecular and collective dynamics in rodlike and wormlike micelles by proton nuclear magnetic resonance relaxation

Hypothesis: Sodium oleate (NaOL) self-aggregates in water forming rodlike micelles with different length depending on NaOL concentration; when KCl is added wormlike micelles form, which entangle giving rise to a viscoelastic dispersion. It is expected that aggregates with different size and shape exhibit different internal and overall molecular motions and collective dynamics. Experiments: Two low viscosity NaOL/water and two viscoelastic NaOL/KCl/water formulations with different NaOL concentration (0.23 and 0.43 M) were investigated by 1H fast field cycling NMR relaxometry over broad temperature and Larmor frequency ranges, after a first screening by 1H and 13C NMR spectroscopy at high frequency. Findings: The analysis of the collected data indicated that fast conformational isomerization and rotation of NaOL about its long molecular axis and lateral diffusion of NaOL around the axis of the cylindrical aggregates are slightly affected by the aggregate shape and length. On the other hand, fluctuations of the local order director are quite different in the fluid and viscoelastic systems, reflecting the shape and size of the aggregates. Quantitative information was obtained on activation energy for fast internal and overall motions, correlation times and activation energy for lateral diffusion, and coherence length for collective order fluctuations

Efficacy, safety and feasibility of intravenous iloprost in the domiciliary treatment of patients with ischemic disease of the lower limbs

Objective: Intravenous iloprost is an important option in the treatment of ischemic disease of the lower limbs; however, the administration of therapy is frequently compromised because of the need for long cycles of infusion in a hospital setting. The aim of the study is to evaluate the efficacy, safety, feasibility, and the economic impact of infusion therapy in the outpatient setting. Patients and methods: Twenty-four consecutive patients were treated with iloprost at their homes where they were administered a slow rate of infusion for 24 hours a day, during 9.9 ± 2.3 days, with a portable syringe pump (Infonde®). Results: The clinical condition of patients evaluated with the modified SVS/ISCVS scale significantly improved after treatment (+1.29 ± 1.04 points vs. baseline, p<0.001). The drug was well tolerated; neither significant adverse events associated with medication nor problems related to venous access were recorded at home. Ninety-six percent of patients successfully completed the entire treatment cycle, and the evaluation questionnaire showed a high acceptance of the therapy. From the perspective of the hospital authority, lower direct medical costs were estimated for the domiciliary infusion process compared with the inpatient infusion setting. Conclusions: Treatment with iloprost in the outpatient setting is effective, safe, feasible, and more acceptable to patients than infusion at the hospital. In addition, it has a favorable economic and organizational impact on the medical ward